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  • Springer  (163,687)
  • American Physical Society  (27,085)
  • 2015-2019  (124,361)
  • 1985-1989  (66,411)
  • 2015  (124,361)
  • 1989  (66,411)
Collection
Keywords
Publisher
Years
  • 2015-2019  (124,361)
  • 1985-1989  (66,411)
Year
  • 1
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    Long-Term Disaster-Prevention Strategies Based on Education (2015)
    Springer
    Details
    Publication Date: 2020-12-23
    Description: Although human behavior is the crucial factor in the degree of vulnerability and the likelihood of disasters taking place, preparedness and prevention programs are not mandatory in all countries around the world. Within the framework of UPStrat-MAFA (Urban disaster Prevention Strategies using MAcroseismic FAults), we have defined the disaster prevention strategies based on education management information and actions taken in Iceland, Portugal, Spain, and Italy. A detailed comparative study shows that compulsory school in these four participating countries is greatly unprepared with regard to hazard education, and these results are in line with worldwide studies. Moreover, when hazards are addressed, this is not done at an early age, which results in a missed chance to intervene in the noncognitive side of awareness, which decreases at later ages. To comply with the urge to take actions towards training and education at an early age, we used hands-on tools and learn-by-playing approaches in an informal learning environment. To reach the older population, the audio- visual media appears to be the best and lowest cost alternative to promote risk perception, awareness and education.
    Description: Published
    Description: 77-80
    Description: 3T. Pericolosità sismica e contributo alla definizione del rischio
    Description: restricted
    Keywords: Disaster prevention ; Education ; Seismic hazard ; Information strategies ; 04. Solid Earth::04.06. Seismology::04.06.99. General or miscellaneous
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: book chapter
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  • 2
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    The European experience of educational seismology (2015)
    Springer
    Details
    Publication Date: 2020-11-25
    Description: This chapter provides an overview of last two decades, European experiences in educational seismology and describes the different contexts in which they have been developed. The basic idea of these educational projects is that Seismology may represent an efficient communication vehicle for teaching a wide range of basic Earth sci-ence topics through laboratory practices and educational activities. Moreover it is also an effective tool to raise in the young citizens the awareness on the earthquake risk and possible mitigation actions. In this frame several seismic stations with different technologies were installed in schools across Europe. The scientific support of re-searchers and the need to establish strong links between teachers and researchers attribute to the school an active role in the knowledge process using the scientific laboratory practice by adopting the “learning by doing” modern approach of science communication (R. Schank and C. Cleary, 1995, Engines for Education, Ed. Routledge, 248 pp). Some educational activities correlated with seismological projects are presented, following different strategies depending on the country, but all aimed at building a new way to communicate science in the schools. The new vogue is the opening toward social networks and blogs. This generalizes the concept of an educational Geoscience website making it an e-platform for science communication and multimedia data sharing, where researchers, teachers, students and education op-erators can interact and constantly be kept informed of ongoing activities and relevant events. All of these 'seismology at school' initiatives rely on the concept of school networking and will merge in the European project NERA (Network of European Research Infrastructures for Earthquake Risk Assessment and Mitigation, http://www.nera-eu.org/) where a spe-cific workpackage is dedicated to networking school seismology programs.
    Description: Published
    Description: 145-170
    Description: 3T. Pericolosità sismica e contributo alla definizione del rischio
    Description: restricted
    Keywords: educational seismology ; educational projects ; learning by doing ; science communication ; school seismology ; 05. General::05.03. Educational, History of Science, Public Issues::05.03.99. General or miscellaneous
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: book chapter
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  • 3
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    Applying the Disruption Index Procedure to Evaluate the Urban Seismic Risk in the Mt. Etna Area (Italy) (2015)
    Springer
    Details
    Publication Date: 2020-12-23
    Description: The Disruption Index is used here for the assessment of urban disruption in the Mt. Etna area after a natural disaster. The first element of the procedure is the definition of the seismic input, which is based on information about the historical seismicity and seismogenic faults. The second element is the computation of the seismic impact on the building stock and infrastructure in the region considered. Information on urban-scale vulnerability was collected and a geographic information system was used to organize the data relating to buildings and network systems (e.g., typologies, schools, strategic structures, lifelines). The central idea underlying the definition of the Disruption Index is the identification and evaluation of the impacts on a target community, considering the physical elements that contribute most to the severe disruption. The results of this study are therefore very useful for earthquake preparedness planning and for the development of strategies to minimize the risks from earthquakes. This study is a product of the European “Urban Disaster Prevention Strategies using Macroseismic Fields and Fault Sources” project (UPStrat-MAFA European project 2013).
    Description: Published
    Description: Torino
    Description: 3T. Pericolosità sismica e contributo alla definizione del rischio
    Description: open
    Keywords: Seismic impact ; Disruption index ; Urban system ; Risk measures ; Mt. Etna area (Italy) ; 04. Solid Earth::04.06. Seismology::04.06.11. Seismic risk
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: Conference paper
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  • 4
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    Towards multi-resolution global climate modeling with ECHAM6–FESOM. Part I: model formulation and mean climate (2015)
    Springer
    In:  EPIC3Climate Dynamics, Springer, 44(3), pp. 757-780, ISSN: 0930-7575
    Details
    Publication Date: 2017-01-27
    Description: A new climate model has been developed that employs a multi-resolution dynamical core for the sea ice-ocean component. In principle, the multi-resolution approach allows one to use enhanced horizontal resolution in dynamically active regions while keeping a coarse-resolution setup otherwise. The coupled model consists of the atmospheric model ECHAM6 and the finite element sea ice-ocean model (FESOM). In this study only moderate refinement of the unstructured ocean grid is applied and the resolution varies from about 25 km in the northern North Atlantic and in the tropics to about 150 km in parts of the open ocean; the results serve as a benchmark upon which future versions that exploit the potential of variable resolution can be built. Details of the formulation of the model are given and its performance in simulating observed aspects of the mean climate is described. Overall, it is found that ECHAM6–FESOM realistically simulates many aspects of the observed climate. More specifically it is found that ECHAM6–FESOM performs at least as well as some of the most sophisticated climate models participating in the fifth phase of the Coupled Model Intercomparison Project. ECHAM6–FESOM shares substantial shortcomings with other climate models when it comes to simulating the North Atlantic circulation.
    Repository Name: EPIC Alfred Wegener Institut
    Type: Article , isiRev
    Format: application/pdf
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  • 5
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    Laboratory activities for seismic and volcanic hazards education: a challenge for scientists (2015)
    Springer
    Details
    Publication Date: 2017-04-04
    Description: Balanced information and education are fundamental prerequisites for risk prevention and preparedness. Among others, children embody our best chance to implant appropriate behaviors that will be recalled during hazardous situations and to involve adults according to a knowledge chain reaction. In this work, scientists challenge their communication skills to built a set of hands-on and learn-by-play based laboratory activities, for primary and secondary schools, addressing three major issues: (1) the location of earthquakes and volcanoes on Earth; (2) earthquakes and eruptions mechanisms; (3) earthquakes unpredictability. Students are asked to place volcanoes and earthquakes epicenters (issue 1) on a wooden plate puzzle according to Plate dynamics. To addresses eruption mechanisms (issue 2) and related hazard, we use backing soda forced blowing out from a volcano vent and suggest that a pyroclastic flow is fast, it can spread over a large area and raise high up to the stratosphere. Earthquake mechanisms (issue 2) are discussed describing the energy buildup, release, and transfer, using a wooden sticks bendand- break analogy. The display of acoustic waves caused by the breakage in different situations allows understanding of both the rupture energy and the wave attenuation. Earthquakes occurrence (issue 3) is addressed using steadily pulled blocks sliding on a frictional surface, where pins simulate asperities. These activities were tested, involving thousands of students. Discussions with students and teachers and the analysis of the answers to specific questionnaires gave us confidence that we proposed proper tools to raise risk awareness
    Description: Published
    Description: 89-93
    Description: 3T. Pericolosità sismica e contributo alla definizione del rischio
    Description: restricted
    Keywords: Seismic and volcanic hazards, Outreach, Education ; 05. General::05.09. Miscellaneous::05.09.99. General or miscellaneous
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: book chapter
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  • 6
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    Cloudy with a Chance of ideas! ( Piovono idee!): an interactive learning experience on hydrogeological risk and climate change (2015)
    Springer
    Details
    Publication Date: 2017-04-04
    Description: On October 25th 2011 a devastating flood hit the Vara and Magra valleys in Italy and left an unforgettable scratch in the inhabitants’ minds. Cloudy with a Chance of ideas! (Piovono idee!) is an active journey of discovery and training on hydrogeological risk and climate change. Land preservation and safety of people living on it are issues, which we would like to help citizens get perception about, in order to instill awareness on the actions that can be taken towards risk mitigation. Cloudy with a Chance of ideas! stemmed from this belief, and it is the result of a collaborative planning in which primary and secondary school students, living within cities heavily hit by the flood, took actively part. Children were helped by experts and scientists to build an exhibition devoted to hydrogeological risk. Here interactive workspaces, games and educational laboratories, allow visitors explore concepts, phenomena and their consequences on land and inhabitants. Issues are addressed from a daily actions perspective, where everybody might make the difference towards sustainability and trigger good practices on natural hazards risk reduction.
    Description: Published
    Description: 121-124
    Description: 4A. Clima e Oceani
    Description: restricted
    Keywords: hydrogeological risk, climate change, prevention, environmental impact, territory. ; 01. Atmosphere::01.01. Atmosphere::01.01.02. Climate
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: book chapter
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  • 7
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    Prediction of the shear wave velocity Vs from CPT and DMT at research sites (2015)
    Springer
    Details
    Publication Date: 2017-04-04
    Description: The paper examines the correlations to obtain rough estimates of the shear wave velocity VS from nonseismic dilatometer tests (DMT) and cone penetration tests (CPT). While the direct measurement of VS is obviously preferable, these correlations may turn out useful in various circumstances. The experimental results at six international research sites suggest that the DMT predictions of VS from the parameters ID (material index), KD (horizontal stress index), MDMT (constrained modulus) are more reliable and consistent than the CPT predictions from qc (cone resistance), presumably because of the availability, by DMT, of the stress history index KD.
    Description: Published
    Description: 83-92
    Description: 3T. Pericolosità sismica e contributo alla definizione del rischio
    Description: N/A or not JCR
    Description: restricted
    Keywords: horizontal stress index ; shear wave velocity ; flat dilatometer test ; cone penetration test ; 04. Solid Earth::04.06. Seismology::04.06.11. Seismic risk
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 8
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    Perception of risk for volcanic hazard in Indian Ocean: La Réunion Island case study. (2015)
    Springer
    Details
    Publication Date: 2020-02-24
    Description: In 2011 a research project on volcanic risk assessment at La Réunion Island (Project Aléa, Institute de Physique du Globe de Paris, France) was conducted in order to determine more efficient strategies to manage future volcanic crises. The project included the evaluation of volcanic scenarios through field and historical data analysis, as well as a survey on volcanic risk perception in resident population. A clear scientific information and an effective communication with public play a crucial role in risk mitigation strategies. In particular, the evaluation of the public perception during both volcanic crises and dormant periods is an important element in developing actions focused on specific social and cultural contexts. A questionnaire was developed based on the ones used in similar researches conducted on Italian active volcanoes. Items were designed to measure variables connected with personal perception of hazard and risk, trust in mitigation actions and in information received about these aspects. In addition, specific items related to the peculiarities of La Réunion Island environment were included. A total of 2,000 questionnaires were distributed taking into account factors such as the proximity to the volcano and the involvement of communities in recent volcanic emergencies. Main results coming out from this survey, if on the one hand show an adequate residents’ perception of natural hazards, on the other hand highlight their poor knowledge of the island’ active volcano, a similar lacking knowledge of emergency plan for volcanic crises, but also a high confidence in scientists to provide accurate and reliable information on volcanic risk and hazards in contrast with Local Authorities. Remarkable findings of this study assess some key elements that should be considered by the institutions in charge for defining policies aimed to volcanic risk mitigation and management of future volcanic crises.
    Description: Unpublished
    Description: 1V. Storia e struttura dei sistemi vulcanici
    Description: reserved
    Keywords: risk perception, volcanic hazards ; 05. General::05.09. Miscellaneous::05.09.99. General or miscellaneous
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: book chapter
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  • 9
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    Engineering Geology for Society and Territory - Volume 7: Education, Professional Ethics and Public Recognition of Engineering Geology (2015)
    Springer
    Details
    Publication Date: 2017-04-04
    Description: This book is one out of 8 IAEG XII Congress volumes, and deals with education and the professional ethics, which scientists, regulators, and practitioners of engineering geology inevitably have to face through the purposes, methods, limitations, and findings of their works. This volume presents contributions on the professional responsibilities of engineering geologists; the interaction of engineering geologists with other professionals; recognition of the engineering geological profession and its particular contribution to society, culture, and economy; and implications for the education of engineering geologists at tertiary level and in further education schemes. Issues treated in this volume are: the position of engineering geology within the geo-engineering profession; professional ethics and communication; resource use and re-use; managing risk in a litigious world; engineering and geological responsibility; and engineering geology at tertiary level. The Engineering Geology for Society and Territory volumes of the IAEG XII Congress held in Torino from September 15-19, 2014, analyze the dynamic role of engineering geology in our changing world and build on the four main themes of the congress: Environment, processes, issues, and approaches.
    Description: Published
    Description: 3T. Pericolosità sismica e contributo alla definizione del rischio
    Description: 5A. Energia e georisorse
    Description: 6A. Monitoraggio ambientale, sicurezza e territorio
    Description: open
    Keywords: Geoethics ; Geoeducation ; Professional Ethics ; Engineering Geology ; Communication ; Society ; Risks management ; Georesources ; Geological responsibility ; 05. General::05.03. Educational, History of Science, Public Issues::05.03.99. General or miscellaneous ; 05. General::05.09. Miscellaneous::05.09.99. General or miscellaneous
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: book
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  • 10
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    Natural Gas Seepage (2015)
    Springer
    Details
    Publication Date: 2017-04-04
    Description: Published
    Description: 7A. Geofisica di esplorazione
    Description: reserved
    Keywords: Gas seepage, methane ; 04. Solid Earth::04.04. Geology::04.04.12. Fluid Geochemistry
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: book
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  • 11
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    Geosystemics, entropy and criticality of earthquakes: a vision of our planet and a key of access (2015)
    Springer
    Details
    Publication Date: 2017-04-04
    Description: Earth is a system of interconnected systems, whose complexity is far from being fully understood by a reductionist approach alone. In this chapter we introduce the concept of geosystemics and the use of the entropy to characterize some aspects of the phenomena under study. We will show how entropy and criticality of the system are central to better understand the most important general features of earthquakes. We will analyze two recent seismic sequences culminated with a main-shock (2009 L’Aquila and 2012 Emilia, both in Italy) to show the potential of this approach and to understand some important characteristics of the seismicity under scrutiny.
    Description: Published
    Description: 3-20
    Description: 4T. Fisica dei terremoti e scenari cosismici
    Description: restricted
    Keywords: geosystemics, earthquake, complexity ; 04. Solid Earth::04.06. Seismology::04.06.99. General or miscellaneous
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: book chapter
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  • 12
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    Geoethical aspects in the natural hazards management (2015)
    Springer
    Details
    Publication Date: 2017-04-04
    Description: The defence against natural hazards involves many actors with different roles: geoscientists, decision makers, local authorities, mass media, citizens. A proper management of georisks requires that each role is well-defined and governed by shared operational protocols, especially during the emergency phase, so that overlapping and misunderstanding don’t jeopardize population safety and economic activities. To achieve good results in this direction, it is necessary to undertake a careful evaluation of the limits and expectations of each component of society and the respect of legitimate aspirations and prerogatives. An effective defence system against natural hazards should be planned rationally and based on scientific data, in order to avoid alarmism among citizens, misleading sensationalism by media, careless decisions by politicians, as well as approximation in managing different phases of the risk cycle. Taking into consideration geoethical aspects related to natural hazards can be helpful to make geoscientists aware of their responsibilities towards society and to clarify the role they can play in the interaction with other actors, aiming at more efficacious actions for georisk mitigation.
    Description: Published
    Description: 59-62
    Description: 4T. Fisica dei terremoti e scenari cosismici
    Description: 4V. Vulcani e ambiente
    Description: 4A. Clima e Oceani
    Description: 6A. Monitoraggio ambientale, sicurezza e territorio
    Description: restricted
    Keywords: Geoethics ; Natural hazards ; Risks ; Society ; Responsibility ; 05. General::05.03. Educational, History of Science, Public Issues::05.03.99. General or miscellaneous ; 05. General::05.08. Risk::05.08.99. General or miscellaneous ; 05. General::05.09. Miscellaneous::05.09.99. General or miscellaneous
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 13
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    What’s the seismic risk perception in Italy? (2015)
    Springer
    Details
    Publication Date: 2017-04-04
    Description: Risk perception is a fundamental element in the definition and the adoption of preventive counter-measures. In order to develop effective information and risk communication strategies, the perception of risks and the influencing factors should be known. This paper presents preliminary results of a survey on seismic risk perception in Italy. The research design combines a psychometric and a cultural theoretic approach. More than 5,000 on-line tests have been compiled from January 23rd till July 25th, 2013. The data collected show that in Italy seismic risk perception is strongly underestimated; 86 on 100 Italian citizens, living in the most dangerous zone (namely Zone 1), do not have a correct perception of seismic hazard. From these observations we deem that extremely urgent measures are required in Italy to reach an effective way to communicate seismic risk"This study has benefited from funding provided by the Italian Presidenza del Consiglio dei Ministri - Dipartimento di Protezione Civile (DPC). This paper does not necessarily represent DPC official opinion and policies".
    Description: Published
    Description: 69-75
    Description: 3T. Pericolosità sismica e contributo alla definizione del rischio
    Description: open
    Keywords: Risk perception ; Seismic hazard ; Hazard communication ; Seismic risk ; 05. General::05.03. Educational, History of Science, Public Issues::05.03.99. General or miscellaneous
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: book chapter
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  • 14
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    Natural tritium determination in groundwater on Mt. Etna (Sicily, Italy) (2015)
    Springer
    Details
    Publication Date: 2017-04-04
    Description: Tritium is a naturally occurring radionuclide, due to interactions of cosmic-rays with the upper layers of the atmosphere; but its presence in the environment is mainly due to residual fallout from nuclear weapons atmosphere tests, carried out from 1952 till 1980. Tritium reaches the Earth’s surface mainly in the form of precipitation, becoming part of the hydrological cycle, then the interest of tritium content analysis in drinking water is both for dosimetry and health-risk and for using tritium as a natural tracer in the groundwater circulation system. This paper presents results from a survey carried out in the Mt. Etna area (east and west flanks) and in the southern side of Nebrodi in Sicily (Italy), in order to determine tritium activity concentrations in water samples by using liquid scintillation counter. The investigated areas show quite low tritium concentrations, much below the Italian limit of 100 Bq L-1 for drinking water and even comparable with the minimum detectable activity value. The effective dose due to tritium for public drinking water consumption was also evaluated.
    Description: Published
    Description: 861-866
    Description: 6A. Monitoraggio ambientale, sicurezza e territorio
    Description: JCR Journal
    Description: restricted
    Keywords: Tritium ; Tritiated water ; Liquid scintillation ; Mt. Etna ; Drinking water ; 03. Hydrosphere::03.04. Chemical and biological::03.04.07. Radioactivity and isotopes
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 15
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    Archeoseismology in Sicily: past earthquakes and effects on society (2015)
    Springer
    Details
    Publication Date: 2017-04-04
    Description: This work presents a review of archeological evidence of strong earthquakes occurring in Sicily at a time of Greek and Roman colonization, a period of considerable political, economic and social instability. In this historical context, the earthquake effects may have been obscured or overlooked to some extent and consequently the documentary information on ancient earthquakes, when available, is often sparse and lacking objectivity. The studied cases combine historical and archaeological data together with the evidence of structural damage to archaeological sites. Looking into past, the vocation of archaeoseismology lies in the identification of past seismic events, and particularly what the ancient society knew on earthquakes, and what kind of seismic effects produced on buildings and sites.
    Description: Unpublished
    Description: 491-504
    Description: 2T. Tettonica attiva
    Description: restricted
    Keywords: Archaeoseismology ; Historical seismicity ; 04. Solid Earth::04.06. Seismology::04.06.05. Historical seismology
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 16
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    A comparison of surface and underground array measurements of ambient noise recorded in Naples (Italy). (2015)
    Springer
    Details
    Publication Date: 2020-02-24
    Description: Abstract In this study, we describe two experiments of seismic noise measurements carried out in Naples, Italy. The site allowed measurements to be obtained both at the surface and in a tunnel that is 120-m-deep. The main goal was to compare the seismic response evaluated at the surface to the in-tunnel response, through spectral, polarization, and resonance directivity analyses. In the 1 to 20 Hz frequency band, the noise level was up to 15 dB higher at the surface than in the tunnel. The polarization properties and horizontal-to-vertical spectral ratios appear not to be influenced by the tunnel geometry or by the topography. Some preferential alignments were observed in the polarization azimuths computed at the surface, which are likely to be due to local sources, rather than morphological features. The absence of directivity effects and the low noise levels in the tunnel make this site suitable for installing seismic stations. We also studied how the subsoil structure affects the seismic motion at the surface. The dispersive properties of the Rayleigh waves were investigated using the spatial autocorrelation method. A joint inversion of the dispersion data and the horizontal-to-vertical spectral ratios provided the subsurface Vs profile. The derived model has a low velocity contrast at depth, such as to generate moderate and broad H/V spectral ratio peak amplitude. The normalized spectral ratio appears more appropriate to identify the soil-resonance frequencies.
    Description: Published
    Description: 385 - 400
    Description: 4T. Fisica dei terremoti e scenari cosismici
    Description: JCR Journal
    Description: restricted
    Keywords: seismic noise ; 04. Solid Earth::04.06. Seismology::04.06.09. Waves and wave analysis
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 17
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    Seismic Microzonation in a Small Municipality: The Canazei Case Study (Trentino, N Italy) (2015)
    Springer
    Details
    Publication Date: 2020-02-24
    Description: The results of a detailed seismic microzonation study performed at Canazei (Trentino—Northern Italy) are here presented. We investigated the local seismic response of this small village using a Level 3 seismic microzonation, the most accurate according to the Italian Code of Seismic Microzonation. This method consists of gradual steps of knowledge to consider different aspects of the amplification phenomena. A multidisciplinary approach has been performed, including a local geological study, geophysical investigations, geotechnical characterization of lithologies and numerical analyses. The obtained elastic response spectra were compared to the spectra prescribed by the Italian Building Code. Our results show the geologic and geophysical subsoil heterogeneities, responsible for different local seismic responses in terms of acceleration spectra and amplification factors.
    Description: Published
    Description: 1085-1089
    Description: 3T. Pericolosità sismica e contributo alla definizione del rischio
    Description: reserved
    Keywords: Seismic microzonation ; Response spectra ; Amplification factor ; Canazei ; 04. Solid Earth::04.06. Seismology::04.06.04. Ground motion ; 04. Solid Earth::04.06. Seismology::04.06.06. Surveys, measurements, and monitoring ; 04. Solid Earth::04.06. Seismology::04.06.11. Seismic risk
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 18
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    Geoscientific Communication Problem with Communities for Disaster Prevention and Land Planning in Peru (2015)
    Springer
    Details
    Publication Date: 2020-02-24
    Description: The communication process between the geoscientists and native communities in risk areas can significantly affect disaster prevention and land use planning. In Peru, the problem of disaster prevention is a fundamental policy due to unfamiliarity and deficiency of the associate information on the population. It is possible that talk of disaster prevention it will be an unlikely ideal in a country where most towns have settled on unplanned projects by the constant change and the lack of interest from the authorities in such topics. However, it is anachronistic that the rural communities and towns continue to live without a plan to enable them to improve their quality of life. The correct use of geoscience information in the mass media can help in this work. The characteristics of the enterprise in Peru require more training by professionals in the geosciences and support communication specialists. In this paper, we analyze the problem of communication for disaster prevention in Peru, with the aim of contributing to the articulation of a disaster prevention strategy.
    Description: Published
    Description: 81-83
    Description: 3T. Pericolosità sismica e contributo alla definizione del rischio
    Description: 4V. Vulcani e ambiente
    Description: 6A. Monitoraggio ambientale, sicurezza e territorio
    Description: reserved
    Keywords: Communication process ; Disaster prevention ; Risk management ; Peru ; Geoethics ; 04. Solid Earth::04.06. Seismology::04.06.11. Seismic risk ; 04. Solid Earth::04.08. Volcanology::04.08.08. Volcanic risk ; 05. General::05.03. Educational, History of Science, Public Issues::05.03.99. General or miscellaneous ; 05. General::05.08. Risk::05.08.99. General or miscellaneous ; 05. General::05.09. Miscellaneous::05.09.99. General or miscellaneous
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 19
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    The Kongsfjorden Channel System offshore NW Svalbard: downslope sedimentary processes in a contour-current-dominated setting (2015)
    Springer
    In:  EPIC3Arktos, Springer, 1(1), ISSN: 2364-9453
    Details
    Publication Date: 2017-01-03
    Description: Submarine channel systems on and off glaciated continental margins can be up to hundreds of kilometres long, tens of kilometres wide and hundreds of metres deep. They result from repeated erosion and various downslope processes predominantly during glacial periods and can, therefore, provide valuable tools for the reconstruction of past ice-sheet dynamics. The Kongsfjorden Channel System (KCS) on the continental slope off northwest Svalbard provides evidence that downslope sedimentary processes are locally more dominant than regional along-slope sedimentation. It is a relatively short channel system (*120 km) that occurs at a large range of water depths (*250–4000 m) with slope gradients varying between 0 and 20. Multiple gullies on the Kongsfjorden Trough Mouth Fan merge to small channels that further merge to a main channel. The overall location of the channel system is controlled by variations in slope gradients and the ambient regional bathymetry. The widest and deepest incisions occur in areas of the steepest slope gradients. The KCS has probably been active since *1 Ma when glacial activity on Svalbard increased and grounded ice expanded to the shelf break off Kongsfjorden repeatedly. Activity within the system was probably highest during glacials. However, reduced activity presumably took place also during interglacials.
    Repository Name: EPIC Alfred Wegener Institut
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    Recent foraminifera in the Arctic Ocean and Kara Sea continental margin (2015)
    Springer
    In:  EPIC3Arktos, Springer, pp. 0-17
    Details
    Publication Date: 2016-02-28
    Repository Name: EPIC Alfred Wegener Institut
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    Pteropod sedimentation patterns in different water depths observed with moored sediment traps over a 4-year period at the LTER station HAUSGARTEN in eastern Fram Strait (2015)
    Springer
    In:  EPIC3Polar Biol, Springer, ISSN: 0722-4000
    Details
    Publication Date: 2015-02-10
    Description: Pteropods are important organisms in highlatitude ecosystems, and they are expected to severely suffer from climate change in the near future. In this study, sedimentation patterns of two pteropod species, the polar Limacina helicina and the subarctic boreal L. retroversa, are presented. Time series data received by moored sediment traps at the Long-Term Ecological Research (LTER) Observatory HAUSGARTEN in eastern Fram Strait were analyzed during the years 2008 to 2012. Results were derived from four different deployment depths (200, 1,250, 2,400, and 2,550 m) at two different sites (79°N 04'200E; 79°430N 04'300E). A species-specific sedimentation pattern was present at all depths and at both sites showing maximal flux rates during September/October for L. helicina and in November/December for L. retroversa. The polar L. helicina was outnumbered by L. retroversa (55–99 %) at both positions and at all depths supporting the recently observed trend toward the dominance of the subarctic boreal species. The largest decrease in pteropod abundance occurred within the mesopelagic zone (*200–1,250 m), indicating loss via microbial degradation and grazing. Pteropod carbonate (aragonite) amounted up to *75 % of the total carbonate flux at 200 m and 2–13 % of the aragonite found in the shallow traps arrived at the deep sediment traps (*160 m above the seafloor), revealing the significance of pteropods in carbonate export at Fram Strait. Our results emphasize the relevance and the need for continuation of long-term studies to detect and trace changes in pteropod abundances and community composition and thus in the vertical transport of aragonite.
    Repository Name: EPIC Alfred Wegener Institut
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    Annual changes of aerosol optical depth and Ångström exponent over Spitsbergen (2015)
    Springer
    In:  EPIC3Free Preview Impact of Climate Changes on Marine Environments, Book, Springer, 15 p., pp. 23-37, ISBN: 978-3-319-14282-1
    Details
    Publication Date: 2020-03-05
    Description: This book contributes to the current discussion on global environmental changes by discussing modifications in marine ecosystems related to global climate changes. In marine ecosystems, rising atmospheric CO2 and climate changes are associated with shifts in temperature, circulation, stratification, nutrient input, oxygen concentration and ocean acidification, which have significant biological effects on a regional and global scale. Knowing how these changes affect the distribution and abundance of plankton in the ocean currents is crucial to our understanding of how climate change impacts the marine environment. Ocean temperatures, weather and climatic changes greatly influence the amount and location of nutrients in the water column. If temperatures and currents change, the plankton production cycle may not coincide with the reproduction cycle of fish. The above changes are closely related to the changes in radiative forcing, which initiate feedback mechanisms like changes in surface temperature, circulation, and atmospheric chemistry.
    Repository Name: EPIC Alfred Wegener Institut
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    Mineral dust variability in Antarctic ice for different climate conditions (2015)
    Springer
    In:  EPIC3Integrated Analysis of Interglacial Climate Dynamics, Springer Briefs in Earth System Sciences, Heidelberg, Springer, pp. 89-95, ISBN: 978-3-319-00692-5
    Details
    Publication Date: 2015-04-07
    Description: This study aims to understand the dust deposition changes on the Antarctic ice sheet in different climatic stages. To this end high resolution dust concentration and size profiles from the EPICA-DML ice core over the transition from the last Glacial to the Holocene (T1) were combined with model experiments for four interglacial time slices and the Last Glacial Maximum (LGM). A strong decrease in dust concentration (factor 46) and a slight increase in dust size was observed during T1. A strong coupling between transport and intensified sources during the Glacial could be derived from the seasonal variability of concentration and size and its phase-lag. This strong coupling vanishes during the Holocene. The model simulates increased dust deposition in Antarctica for all past interglacial time slices compared to the pre-industrial period. The major cause for the increase is enhanced Southern Hemisphere dust emission, but changes in atmospheric transport are also relevant. The maximum dust deposition in Antarctica is simulated for the LGM, showing a 10-fold increase compared to preindustrial conditions.
    Repository Name: EPIC Alfred Wegener Institut
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    Cell-vertex discretization of shallow water equations on mixed unstructured meshes (2015)
    Springer
    In:  EPIC3Ocean Dynamics, Springer, 65(1), pp. 33-47, ISSN: 1616-7341
    Details
    Publication Date: 2015-02-10
    Description: Finite-volume discretizations can be formulated on unstructured meshes composed of different polygons. A staggered cell-vertex finite-volume discretization of shallow water equations is analyzed on mixed meshes composed of triangles and quads. Although triangular meshes are most flexible geometrically, quads are more efficient numerically and do not support spurious inertial modes of triangular cell- vertex discretization. Mixed meshes composed of triangles and quads combine benefits of both. In particular, triangular transitional zones can be used to join quadrilateral meshes of differing resolution. Based on a set of examples involving shallow water equations, it is shown that mixed meshes offer a viable approach provided some background biharmonic viscosity (or the biharmonic filter) is added to stabilize the triangular part of the mesh.
    Repository Name: EPIC Alfred Wegener Institut
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    Snow Accumulation In North Greenland Over The Last Millenium (2015)
    Springer
    In:  EPIC3Towards an Interdisciplinary Approach in Earth System Science, Springer Earth System Sciences, Heidelberg, Springer, 9 p., pp. 197-205, ISBN: 978-3-319-13864-0
    Details
    Publication Date: 2016-11-14
    Description: Knowledge of snow accumulation rates of the large polar ice sheets and their variability over time is crucial for mass budget studies and sea level predictions. Here we present mean long-term snow accumulation rates of 12 shallow ice cores drilled by the North Greenland traverse in the northern part of Greenland. The ice core records cover the last 500 to 1000 years. We find a trend of decreasing accumulation rate from the southwest (~180 mmWE/a) to northeast (~95 mmWE/a). Ice divide sites show higher accumulation rates but also higher variability (up to 20%) than sites off the ice divides (less than 10%). Unlike a recent modeling study our results indicate no change in the accumulation in the north of Greenland during the last 400 years
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    Bivalve Shells—Unique High-Resolution Archives of the Environmental Past (2015)
    Springer
    In:  EPIC3Towards an Interdisciplinary Approach in Earth System Science, (Springer Earth System Sciences), Heidelberg [u.a.], Springer, 251 p., pp. 173-182, ISBN: 978-3-319-13864-0
    Details
    Publication Date: 2015-02-11
    Description: Understanding the climate of the past is essential for anticipating future climate change. Palaeoclimatic archives are the key to the past, but few marine archives (including tropical corals) combine long recording times (decades to centuries) with high temporal resolution (decadal to intra-annual). In temperate and polar regions carbonate shells can perform the equivalent function as a proxy archive as corals do in the tropics. The bivalve Arctica islandica is a particularly unique bio-archive owing to its wide distribution throughout the North Atlantic and its extreme longevity (up to 500 years). This paper exemplifies how information at intra-annual and decadal scales is derived from A. islandica shells and combined into a detailed picture of past conditions. Oxygen isotope analysis (δ18O) provides information on the intra-annual temperature cycle while frequency analysis of shell growth records identifies decadal variability such as a distinct 5-year signal, which might be linked to the North Atlantic Oscillation.
    Repository Name: EPIC Alfred Wegener Institut
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    A Sediment Budget for the Transkei Basin, Southwest Indian Ocean (2015)
    Springer
    In:  EPIC3Marine Geophysical Reseach, Springer, 36, pp. 281-291
    Details
    Publication Date: 2015-11-06
    Description: Deep sea sediment budgets can be used to constrain erosion rates in the neighboring continents from which the material was derived. Here we construct a sediment budget for the Transkei Basin, offshore South Africa using an existing seismic reflection survey and dated by correlation of seismic attributes to dated sections in nearby basins. Backstripping of the sections reveals that sediment accumulation rates fell from 110 to 11 Ma, with a possible period of rapid accumulation from 36 to 34 Ma that may be driven by strengthening of the Antarctic Bottom Water (AABW). The long term trend is linked to erosional degradation of the onshore continental escarpment, formed as a consequence of continental break-up. No change is noted at 30 Ma, coincident with proposed uplift of southern Africa driven by plume activity. The basin shows a significant increase in sediment accumulation after 11 Ma, which we interpret to reflect strengthening and rerouting of the AABW from the south into Transkei Basin, as a far field effect of the start of closure of the Indonesian Throughflow.
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    Evaluation of Eemian and Holocene Climate Trends: Combining Marine Archives with Climate Modelling (2015)
    Springer
    In:  EPIC3Integrated Analysis of Interglacial Climate Dynamics (INTERDYNAMIC), SpringerBriefs in Earth System Sciences, Germany, Springer, 5 p., pp. 31-35, ISBN: 978-3-319-00693-2
    Details
    Publication Date: 2015-06-05
    Description: In an attempt to assess trends of Holocene sea-surface temperature (SST), two proxies have been compiled and analyzed in light of model simulations. The data reveal contrasting SST trends, depending upon the proxy used to derive Holocene SST history. To reconcile these mismatches between proxies in the estimated Holocene SST trends, it has been proposed that the Holocene evolution of orbitally-driven seasonality of the incoming radiation is the first-order driving mechanism of the observed SST trends. Such hypothesis has been further tested in numerical models of the Earth system with important implications for SST signals ultimately recorded by marine sediment cores. The analysis of model results and alkenone proxy data for the Holocene indicate a similar pattern in temperature change, but the simulated SST trends underestimate the proxy-based SST trends by a factor of two to five. SST trends based on Mg/Ca show no correspondence with model results. We explore whether the consideration of different growing seasons and depth habitats of the planktonic organisms used for temperature reconstruction could lead to a better agreement of model results with alkenone data on a regional scale. We found that invoking shifts in the living season and habitat depth can remove some of the model–data discrepancies in SST trends. Our results indicate that modeled and reconstructed temperature trends are to a large degree only qualitatively comparable, thus providing at present a challenge for the interpretation of proxy data as well as the model sensitivity to orbital forcing.
    Repository Name: EPIC Alfred Wegener Institut
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    Social recognition in amphipods: An overview (2015)
    Springer
    In:  EPIC3Social recognition in invertebrates - The knowns and the unknowns, Springer, 16 p., pp. 85-100, ISBN: 978-3-319-17599-7
    Details
    Publication Date: 2015-06-02
    Repository Name: EPIC Alfred Wegener Institut
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    Character, distribution, and ecological significance of storm wave-induced scour in Rhode Island Sound, USA (2015)
    Springer
    Details
    Publication Date: 2022-05-25
    Description: This paper is not subject to U.S. copyright. The definitive version was published in Geo-Marine Letters 35 (2015): 135-144, doi:10.1007/s00367-014-0392-0.
    Description: Multibeam bathymetry, collected during NOAA hydrographic surveys in 2008 and 2009, is coupled with USGS data from sampling and photographic stations to map the seabed morphology and composition of Rhode Island Sound along the US Atlantic coast, and to provide information on sediment transport and benthic habitats. Patchworks of scour depressions cover large areas on seaward-facing slopes and bathymetric highs in the sound. These depressions average 0.5–0.8 m deep and occur in water depths reaching as much as 42 m. They have relatively steep well-defined sides and coarser-grained floors, and vary strongly in shape, size, and configuration. Some individual scour depressions have apparently expanded to combine with adjacent depressions, forming larger eroded areas that commonly contain outliers of the original seafloor sediments. Where cobbles and scattered boulders are present on the depression floors, the muddy Holocene sands have been completely removed and the winnowed relict Pleistocene deposits exposed. Low tidal-current velocities and the lack of obstacle marks suggest that bidirectional tidal currents alone are not capable of forming these features. These depressions are formed and maintained under high-energy shelf conditions owing to repetitive cyclic loading imposed by high-amplitude, long-period, storm-driven waves that reduce the effective shear strength of the sediment, cause resuspension, and expose the suspended sediments to erosion by wind-driven and tidal currents. Because epifauna dominate on gravel floors of the depressions and infauna are prevalent in the finer-grained Holocene deposits, it is concluded that the resultant close juxtaposition of silty sand-, sand-, and gravel-dependent communities promotes regional faunal complexity. These findings expand on earlier interpretations, documenting how storm wave-induced scour produces sorted bedforms that control much of the benthic geologic and biologic diversity in Rhode Island Sound.
    Description: This work was supported by the Coastal and Marine Geology Program of the U.S. Geological Survey and the Atlantic Hydrographic Branch of the National Oceanic and Atmospheric Administration.
    Repository Name: Woods Hole Open Access Server
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    Pond fractals in a tidal flat (2015)
    American Physical Society
    Details
    Publication Date: 2022-05-25
    Description: © The Author(s), 2015. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Physical Review E Statistical, Nonlinear, and Soft Matter Physics 92 (2015): 052128, doi: 10.1103/PhysRevE.92.052128.
    Description: Studies over the past decade have reported power-law distributions for the areas of terrestrial lakes and Arctic melt ponds, as well as fractal relationships between their areas and coastlines. Here we report similar fractal structure of ponds in a tidal flat, thereby extending the spatial and temporal scales on which such phenomena have been observed in geophysical systems. Images taken during low tide of a tidal flat in Damariscotta, Maine, reveal a well-resolved power-law distribution of pond sizes over three orders of magnitude with a consistent fractal area-perimeter relationship. The data are consistent with the predictions of percolation theory for unscreened perimeters and scale-free cluster size distributions and are robust to alterations of the image processing procedure. The small spatial and temporal scales of these data suggest this easily observable system may serve as a useful model for investigating the evolution of pond geometries, while emphasizing the generality of fractal behavior in geophysical surfaces.
    Description: This material is based upon work supported by the National Science Foundation Graduate Research Fellowship Program under Grant No. 2388357, the Gordon and Betty Moore Foundation, and the National Science Foundation, Award No. OCE-1315201.
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    Heaving modes in the world oceans (2015)
    Springer
    Details
    Publication Date: 2022-05-25
    Description: © The Author(s), 2015. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Climate Dynamics 45 (2015): 3563-3591, doi:10.1007/s00382-015-2557-6.
    Description: Part of climate changes on decadal time scales can be interpreted as the result of adiabatic motions associated with the adjustment of wind-driven circulation, i.e., the heaving of the isopycnal surfaces. Heat content changes in the ocean, including hiatus of global surface temperature and other phenomena, can be interpreted in terms of heaving associated with adjustment of wind-driven circulation induced by decadal variability of wind. A simple reduced gravity model is used to examine the consequence of adiabatic adjustment of the wind-driven circulation. Decadal changes in wind stress forcing can induce three-dimensional redistribution of warm water in the upper ocean. In particular, wind stress change can generate baroclinic modes of heat content anomaly in the vertical direction; in fact, changes in stratification observed in the ocean may be induced by wind stress change at local or in the remote parts of the world oceans. Intensification of the equatorial easterly can induce cooling in the upper layer and warming in the subsurface layer. The combination of this kind of heat content anomaly with the general trend of warming of the whole water column under the increasing greenhouse effect may offer an explanation for the hiatus of global surface temperature and the accelerating subsurface warming over the past 10–15 years. Furthermore, the meridional transport of warm water in the upper ocean can lead to sizeable transient meridional overturning circulation, poleward heat flux and vertical heat flux. Thus, heaving plays a key role in the oceanic circulation and climate.
    Keywords: Adiabatic motions ; Heaving ; Subtropical and subpolar gyres ; Southern oceans ; Baroclinic modes of heating content anomaly ; Wind-driven circulation ; Climate variability of heat content
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    Quantifying the residence time and flushing characteristics of a shallow, back-barrier estuary : application of hydrodynamic and particle tracking models (2015)
    Springer
    Details
    Publication Date: 2022-05-25
    Description: This paper is not subject to U.S. copyright. The definitive version was published in Estuaries and Coasts 38 (2015): 1719-1734, doi:10.1007/s12237-014-9885-3.
    Description: Estuarine residence time is a major driver of eutrophication and water quality. Barnegat Bay-Little Egg Harbor (BB-LEH), New Jersey, is a lagoonal back-barrier estuary that is subject to anthropogenic pressures including nutrient loading, eutrophication, and subsequent declines in water quality. A combination of hydrodynamic and particle tracking modeling was used to identify the mechanisms controlling flushing, residence time, and spatial variability of particle retention. The models demonstrated a pronounced northward subtidal flow from Little Egg Inlet in the south to Pt. Pleasant Canal in the north due to frictional effects in the inlets, leading to better flushing of the southern half of the estuary and particle retention in the northern estuary. Mean residence time for BB-LEH was 13 days but spatial variability was between ∼0 and 30 days depending on the initial particle location. Mean residence time with tidal forcing alone was 24 days (spatial variability between ∼0 and 50 days); the tides were relatively inefficient in flushing the northern end of the Bay. Scenarios with successive exclusion of physical processes from the models revealed that meteorological and remote offshore forcing were stronger drivers of exchange than riverine inflow. Investigations of water quality and eutrophication should take into account spatial variability in hydrodynamics and residence time in order to better quantify the roles of nutrient loading, production, and flushing.
    Description: Funding was provided by the New Jersey Department of Environmental Protection and the Coastal and Marine Geology Program of the U.S. Geological Survey.
    Keywords: Hydrodynamic modeling ; Residence time ; Particle tracking ; Back-barrier estuaries ; Eutrophication
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    Ontology-based mediation of OGC catalogue service for the Web requests: a virtual solution for integrating coastal web atlases. (2015)
    Springer | Berlin
    Details
    Publication Date: 2021-05-19
    Description: In recent years significant momentum has occurred in the development of Internet resources for decision makers and scientists interested in the coast. Chief among these has been the development of coastal web atlases (CWAs). While multiple benefits are derived from these tailor-made atlases (e.g., speedy access to multiple sources of coastal data and information), the potential exists to derive added value from the integration of disparate CWAs, to optimize decision making at a variety of levels and across themes. This paper describes the development of a semantic mediator prototype to provide a common access point to coastal data, maps and information from distributed CWAs. The prototype showcases how ontologies and ontology mappings can be used to integrate different heterogeneous and autonomous atlases, using the Open Geospatial Consortium’s Catalogue Services for the Web.
    Description: Published
    Keywords: Coastal web atlas ; Coastal atlas ; Data semantics ; Semantic web technologies ; Information retrieval ; GIS ; Ontologies ; Catalogue services for the web (CSW) ; Mediation
    Repository Name: AquaDocs
    Type: Conference Material , Refereed
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    North-West African Hydrologic Changes in the Holocene: A Combined Isotopic Data and Model Approach (2015)
    Springer
    In:  EPIC3Integrated Analysis of Interglacial Climate Dynamics (INTERDYNAMIC), (SpringerBriefs in Earth System Sciences), Heidelberg, Springer, 139 p., pp. 109-114, ISBN: 978-3-319-00692-5, ISSN: 2191-589X
    Details
    Publication Date: 2015-02-04
    Description: To achieve a better understanding of the hydrologic evolution of the North-West (NW) African monsoon system during the Holocene, in particular during inferred abrupt climate changes at the end of the African Humid Period (AHP), we investigated terrigenous plant lipids deposited in marine sediments offshore NW Africa. Changes in rainfall amount were estimated by compound-specific hydrogen isotope (δD) analyses. The spatial gradient of rainfall isotopic compositions is reflected in marine surface sediments. δD changes in plant waxes covering the last 100 years confirm the observed decrease in rainfall during the late twentieth century Sahel drought, and thus can be used for a quantitative calibration of δD and pre- cipitation. δD changes in sedimentary plant waxes show no abrupt change at the end of the AHP suggesting a gradual precipitation decline. These results are supported by Holocene climate simulations using a coupled atmosphere-land surface model, which includes an explicit modeling of isotopic fractionation within the hydrological cycle.
    Repository Name: EPIC Alfred Wegener Institut
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    Introduction to Modern Fortran for Earth System Sciences (2015)
    Springer
    In:  EPIC3Heidelberg, Springer, 250 p., ISBN: 978-3-642-37008-3
    Details
    Publication Date: 2015-06-05
    Description: This work provides a short "getting started" guide to Fortran 90/95. The main target audience consists of newcomers to the field of numerical computation within Earth system sciences (students, researchers or scientific programmers). Furthermore, readers accustomed to other programming languages may also benefit from this work, by discovering how some programming techniques they are familiar with map to Fortran 95.
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    Holocene Environmental Variability in the Arctic Gateway (2015)
    Springer
    In:  EPIC3Integrated Analysis of Interglacial Climate Dynamics (INTERDYNAMIC), Integrated Analysis of Interglacial Climate Dynamics (INTERDYNAMIC), Heidelberg, Springer, pp. 37-42, ISBN: 978-3-319-00692-5, ISSN: 2191-589X
    Details
    Publication Date: 2016-05-13
    Description: Environmental changes in the region connecting the Arctic Ocean and the northern North Atlantic were studied for the last 9,000 years (9 ka) by a combination of proxy-based paleoceanographic reconstructions as well as transient and time-slice simulations with climate models. Today, the area is perennially ice-covered in the west and ice-free in the east. Results show that sea-ice conditions were highly variable on short timescales in the last 9 ka. However, sea-ice proxies reveal an overall eastward movement of the sea-ice margin, in line with a decreasing influence of warm Atlantic Water advected to the Arctic Ocean. These cooling trends were rapidly reversed 100 years ago and replaced by the general warming in the Arctic. Model results show a consistently high freshwater input to the Arctic Ocean during the last 7 ka. The signal is robust against the Holocene cooling trend, however sensitive towards the warming trend of the last century. These results may play a role in the observed Arctic changes.
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    Seismostratigraphic analysis and glacial history of the Weddell Sea region, Antarctica (2015)
    Springer
    In:  EPIC3Towards an Interdisciplinary Approach in Earth System Science, (Springer Earth System Sciences), Heidelberg [u.a.], Springer, 251 p., pp. 207-217, ISBN: 978-3-319-13864-0
    Details
    Publication Date: 2023-06-21
    Description: The Weddell Sea basin is of particular significance for understanding climate processes, including the generation of ocean water masses and their influence on ocean circulation as well as the dynamics of the Antarctic ice sheets. The sedimentary record, preserved below the basin floor, serves as an archive of the pre-glacial to glacial development of these processes, which were accompanied by tectonic processes in its early glacial phase. Three multichannel seismic reflection transects, in total nearly 5,000 km long, are used to interpret horizons and define a seismostratigraphic model for the basin. We expand this initial stratigraphy model to the greater Weddell Sea region through a network of more than 50 additional seismic lines. Information from few boreholes are used to constrain sediment ages in this stratigraphy, supported by magnetic anomalies indicating decreasing oceanic basement ages from southeast to northwest. Using these constraints, we calculate grids to depict the depths, thicknesses and sedimentation rates of pre-glacial (145–34 Ma), transitional (34–15 Ma) and full-glacial (15 Ma to present) units. Sedimentation thicknesses and sedimentation rates were calculated at the 12 selected points in the entire basin to give a brief overview of the deposition history, which will contribute to the understanding of the Antarctic ice sheet development and dynamics from the greenhouse to icehouse world in the Cenozoic.
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    Impact of Sea-Ice Bottom Topography on the Ekman Pumping (2015)
    Springer
    In:  EPIC3Towards an Interdisciplinary Approach in Earth System Science, (Springer Earth System Sciences), Heidelberg [u.a.], Springer, Toward, 251 p., pp. 139-148, ISBN: 978-3-319-13865-7
    Details
    Publication Date: 2023-06-21
    Description: Sea-ice elevation profiles and thickness measurements have been collected during summer 2011 in the Central Arctic. These two different data sets have been combined in order to obtain surface and bottom topography of the sea-ice. From the bottom profile, the keels of ridges are detected. Then, a parameterization of oceanic drag coefficients that accounts for the keels depth and density is applied. The calculated oceanic drag coefficients are highly variable (between about 2 × 10−3 and about 8 × 10−3) within the range of observed values. In order to estimate the contribution of variable drag coefficients on the Ekman pumping, the calculated drag coefficients are used in an idealized model experiment, where sea ice is drifting at constant velocity on an ocean at rest. The resulting variations of the Ekman vertical velocity are in the same order of magnitude as for variable ice velocity at the surface. In most state-of-the-art general circulation models, the variations of drag coefficients are not taken into account. The simple experiment carried out in the present study suggests that neglecting this contribution can lead to an incorrect representation of the momentum exchange between ice and ocean and to an underestimation of the Ekman pumping, with consequences for the large scale ocean circulation.
    Repository Name: EPIC Alfred Wegener Institut
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    Earth System Science—Past Experiences and Future Trends (2015)
    Springer
    In:  EPIC3Towards an Interdisciplinary Approach in Earth System Science, Earth System Science—Past Experiences and Future Trends, Heidelberg, Springer, pp. 3-7, ISBN: 978-3-319-13864-0, ISSN: 2197-9596
    Details
    Publication Date: 2023-06-21
    Description: Earth System Science has developed over the last two decades from an interesting concept in Earth sciences education to a fully integrative science focussed on understanding the complex system Earth. This evolution is partially due to the radical and far reaching anthropogenic changes and the general feeling of helplessness with regards to the possible consequences and future impacts on the Earth System. This paper proposes that a paradigm shift in undergraduate and graduate education is needed to further develop Earth System Science. Graduate programs such as the Earth System Science Research School (ESSReS), which are intrinsically trans- and interdisciplinary will help to change rigid subject specific mind-set among faculty and students. The health and sustainability of our planet is at stake
    Repository Name: EPIC Alfred Wegener Institut
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    Integration of Passive Tracers in a Three-Dimensional Ice Sheet Model (2015)
    Springer
    In:  EPIC3Towards an Interdisciplinary Approach in Earth System Science, Towards an Interdisciplinary Approach in Earth System Science, Heidelberg, Springer, pp. 161-170, ISBN: 978-3-319-13864-0, ISSN: 2197-9596
    Details
    Publication Date: 2023-06-21
    Description: Components of the climate system, such as ice sheets and marine sediments serve as invaluable archives, which can be tapped into, to reconstruct paleoclimate conditions. The relative abundance of hydrogen and oxygen isotopes in ice cores is a proxy for past local temperature evolution. However the translation of these proxies into temperature is not straightforward. Complex interdependencies in the climate system can hide or override the local climate signal at which the ice core was drilled. Using 3D ice sheet modelling in concert with passive tracer advection one can simulate the isotopic distribution in ice sheets and compare them to ice core data. Combining this method in a coupled climate model environment, containing atmosphere and ocean components, one can theoretically simulate the isotopic cycle from the source to the actual ice record. Such an approach would greatly support the interpretation of proxy data whilst constraining the output of 3D ice sheet models (ISMs). We present the implementation of passive tracer advection in our 3D ISM RIMBAY (Thoma et al. in Geosci Model Dev 1:1–21, 2014, Goeller et al. in Cryosphere 7:1095–1106, 2014) and asses the potential of the method to reproduce chronologies of the polar ice sheets
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    Marine Litter as Habitat and Dispersal Vector (2015)
    Springer
    In:  EPIC3Marine Anthropogenic Litter, Marine Anthropogenic Litter, Berlin, Springer, 447 p., pp. 141-181, ISBN: 978-3-319-16509-7
    Details
    Publication Date: 2023-06-21
    Description: Floating anthropogenic litter provides habitat for a diverse community of marine organisms. A total of 387 taxa, including pro- and eukaryotic micro-organisms, seaweeds and invertebrates, have been found rafting on floating litter in all major oceanic regions. Among the invertebrates, species of bryozoans, crustaceans, molluscs and cnidarians are most frequently reported as rafters on marine litter. Microorganisms are also ubiquitous on marine litter although the composition of the microbial community seems to depend on specific substratum characteristics such as the polymer type of floating plastic items. Sessile suspension feeders are particularly well-adapted to the limited autochthonous food resources on artificial floating substrata and an extended planktonic larval development seems to facilitate colonization of floating litter at sea. Properties of floating litter, such as size and surface rugosity, are crucial for colonization by marine organisms and the subsequent succession of the rafting community. The rafters themselves affect substratum characteristics such as floating stability, buoyancy, and degradation. Under the influence of currents and winds marine litter can transport associated organisms over extensive distances. Because of the great persistence (especially of plastics) and the vast quantities of litter in the world’s oceans, rafting dispersal has become more prevalent in the marine environment, potentially facilitating the spread of invasive species.
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    Marine Anthropogenic Litter (2015)
    Springer
    In:  EPIC3Berlin, Springer, 447 p., ISBN: 978-3-319-16510-3
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    Publication Date: 2023-06-21
    Description: This book describes how manmade litter, primarily plastic, has spread into the remotest parts of the oceans and covers all aspects of this pollution problem from the impacts on wildlife and human health to socio-economic and political issues. Marine litter is a prime threat to marine wildlife, habitats and food webs worldwide. The book illustrates how advanced technologies from deep-sea research, microbiology and mathematic modelling as well as classic beach litter counts by volunteers contributed to the broad awareness of marine litter as a problem of global significance. The authors summarise more than five decades of marine litter research, which receives growing attention after the recent discovery of great oceanic garbage patches and the ubiquity of microscopic plastic particles in marine organisms and habitats. In 16 chapters, authors from all over the world have created a universal view on the diverse field of marine litter pollution, the biological impacts, dedicated research activities, and the various national and international legislative efforts to combat this environmental problem. They recommend future research directions necessary for a comprehensive understanding of this environmental issue and the development of efficient management strategies. This book addresses scientists, and it provides a solid knowledge base for policy makers, NGOs, and the broader public.
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    Progress in Earth System Science: What Does It Take to Make Our Ideas Clear? (2015)
    Springer
    In:  EPIC3Towards an Interdisciplinary Approach in Earth System Science, Towards an Interdisciplinary Approach in Earth System Science, Heidelberg, Springer, pp. 25-35, ISBN: 978-3-319-13864-0, ISSN: 2197-9596
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    Publication Date: 2023-06-21
    Description: To describe the progress in Earth System Science, a conceptual framework is proposed which includes hypothesis testing, the formulation of models with different complexity as well as expressing discoveries in terms of metaphors. The later approach is demonstrated by the conveyor belt concept in oceanography which influenced the discussion about abrupt climate changes where the ocean circulation may be involved. It is argued that the combination of different methodologies/complexities and independent results is necessary to prevent over-simplistic views in each discipline of Earth System Science. Emphasis is given on typical steps to obtain new ideas for a new discovery. Examples for over-simplistic views are mentioned for past climate information from proxy data. The recorder system of the proxy has to be taken into account, otherwise the climate information can be misinterpreted. It is concluded that in the field of Earth System Science, basic knowledge and true collaborative problem solving is necessary to make scientists aware of the underlying principles, the limitations and open questions. This is furthermore necessary to develop and sharpen our ideas about the complex Earth System.
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    Methodology Used for the Detection and Identification of Microplastics—A Critical Appraisal (2015)
    Springer
    In:  EPIC3Marine Anthropogenic Litter, Marine Anthropogenic Litter, Berlin, Springer, 447 p., pp. 201-227, ISBN: 978-3-319-16510-3
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    Publication Date: 2023-06-21
    Description: Microplastics in aquatic ecosystems and especially in the marine environment represent a pollution of increasing scientific and societal concern, thus, meanwhile a substantial number of studies on microplastics exist. Although first steps towards a standardisation of methodologies used for the detection and identification of microplastics in environmental samples are made, the comparability of data on microplastics is currently hampered by a huge variety of different methodologies which result in the generation of data of extremely different quality and resolution. This chapter reviews the methodology presently used for assessing the concentration of microplastics in the marine environment with focus on the most convenient techniques and approaches. After an overview of non-selective sampling approaches, sample processing and treatment in the laboratory, the reader is introduced to the currently applied techniques for the identification and quantification of microplastics. The subsequent case study on microplastics in sediment samples from the North Sea measured with focal plane array (FPA)-based micro-Fourier transform infrared (micro-FTIR) spectroscopy shows that only 1.4 % of the particles visually resembling microplastics were of synthetic polymer origin. This finding emphasizes the importance of verifying the synthetic polymer origin of potential microplastics. Thus, a burning issue concerning current microplastic research is the generation of standards that allow for the assessment of reliable data on concentrations of microscopic plastic particles and the involved polymers with analytical laboratory techniques such as micro-FTIR or micro-Raman spectroscopy.
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    Evolution of Lightweight Structures: Analyses and Technical Applications (2015)
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    In:  EPIC3Springer, 206 p., ISBN: 9401793972
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    Publication Date: 2022-11-10
    Description: This volume contains studies on the evolution and function of lightweight constructions of planktonic and other organisms, and examples of how they can be used to create new solutions for radical innovations of lightweight constructions for technological application. The principles and underlying processes responsible for evolution and biodiversity of marine plankton organisms are highly relevant and largely unresolved issues in the field of marine science. Amongst the most promising objects for the study of evolution of stable lightweight constructions are marine organisms such as diatoms or radiolarians. Research in these fields requires interdisciplinary expertises such as in evolutionary modelling, paleontology, lightweight optimization, functional morphology, and marine ecology. Considerable effort and expert knowledge in production engineering or lightweight optimization is necessary to transfer knowledge on biogenic structures and evolutionary principles into new lightweight solutions. This book shows methods and examples of how this can be achieved efficiently.
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    The educational program of the Earth System Science Research School (ESSReS) (2015)
    Springer
    In:  EPIC3Towards an Interdisciplinary Approach in Earth System Science, Towards an Interdisciplinary Approach in Earth System Science, Heidelberg, Springer, pp. 9-17, ISBN: 978-3-319-13864-0
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    Publication Date: 2023-06-21
    Description: The Earth System Science Research School (ESSReS) is an international and interdisciplinary research school for 23 PhD students at the Alfred Wegener Institute Helmholtz Centre for Polar and Marine Research (AWI) and their partner universities: University of Bremen and Jacobs University Bremen. ESSReS combines observations, modelling, and data analysis in order to decipher the Earth’s complex climate system. Structured training, international exchange and supervision support interdisciplinary research at an early stage of the scientific career.
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    Geological Storage of CO2 - long term security aspects (2015)
    Springer
    In:  Geotechnologien science report | Advanced Technologies in Earth Sciences
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    Publication Date: 2020-02-12
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    Memory but no suppression in low-dimensional symmetric idiotypic networks (1989)
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    Bulletin of mathematical biology 51 (1989), S. 223-246 
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    ISSN: 1522-9602
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    Topics: Biology , Mathematics
    Notes: Abstract We present a new symmetric model of the idiotypic immune network. The model specifies clones of B-lymphocytes and incorporates: (1) influx and decay of cells; (2) symmetric stimulatory and inhibitory idiotypic interactions; (3) an explicit affinity parameter (matrix); (4) external (i.e. non-idiotypic) antigens. Suppression is the dominant interaction, i.e. strong idiotypic interactions are always suppressive. This precludes reciprocal stimulation of large clones and thus infinite proliferation. Idiotypic interactions first evoke proliferation, this enlarges the clones, and may in turn evoke suppression. We investigate the effect of idiotypic interactions on normal proliferative immune responses to antigens (e.g. viruses). A 2-D, i.e. two clone, network has a maximum of three stable equilibria: the virgin state and two asymmetric immune states. The immune states only exist if the affinity of the idiotypic interaction is high enough. Stimulation with antigen leads to a switch from the virgin state to the corresponding immune state. The network therefore remembers antigens, i.e. it accounts for immunity/memory by switching beteen multiple stable states. 3-D systems have, depending on the affinities, 9 qualitatively different states. Most of these also account for memory by state switching. Our idiotypic network however fails to account for the control of proliferation, e.g. suppression of excessive proliferation. In symmetric networks, the proliferating clones suppress their anti-idiotypic suppressors long before the latter can suppress the former. The absence of proliferation control violates the general assumption that idiotypic interactions play an important role in immune regulation. We therefore test the robustness of these results by abandoning our assumption that proliferation occurs before suppression. We thus define an “escape from suppression” model, i.e. in the “virgin” state idiotypic interactions are now suppressive. This system erratically accounts for memory and never for suppression. We conclude that our “absence of suppression from idiotypic interactions” does not hinge upon our “proliferation before suppression” assumption.
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    Book reviews (1989)
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    Bulletin of mathematical biology 51 (1989), S. 287-291 
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    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Mathematics
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    Editorial: Software survey section (1989)
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    Bulletin of mathematical biology 51 (1989), S. I 
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    Upper and lower bounds from the maximum principle. Intracellular diffusion with Michaelis-Menten kinetics (1989)
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    Bulletin of mathematical biology 51 (1989), S. 325-335 
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    ISSN: 1522-9602
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    Topics: Biology , Mathematics
    Notes: Abstract Analytical bounding functions for diffusion problems with Michaelis-Menten kinetics were recently presented by Anderson and Arthurs, 1985 (Bull. math. Biol. 47, 145–153). Their methods, successful to some extent for a small range of parameters, has the disadvantage of providing a weak upper bound. The optimal approach for the use of one-line bounding kinetics is presented. The use of two-line bounding kinetics is also shown, in order to give, sufficient accuracy in those cases where the one-line approach does not provide satisfactory results. The bounding functions provide excellent upper and lower bounds on the true solution for the entire range of kinetic and transport parameters.
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    The threshold of survival for systems in a fluctuating environment (1989)
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    Bulletin of mathematical biology 51 (1989), S. 311-323 
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    Topics: Biology , Mathematics
    Notes: Abstract Thresholds for survival and extinction are important for assessing the risk of mortality in systems exposed to exogeneous stress. For generic, rudimentary population models and the classical resource-consumer models of Leslie and Gallopin, we demonstrate the existence of a survival threshold for situations where demographic parameters are fluctuating, generally, in a nonperiodic manner. The fluctuations are assumed, to be generated by exogenous, anthropogenic stresses such as toxic chemical exposures. In general, the survival threshold is determined by a relationship between mean stress measure in organisms to the ratio of the population intrinsic growth rate and stress response rate.
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    Plant strategies and the dynamics and structure of plant communities (1989)
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    Bulletin of mathematical biology 51 (1989), S. 409-411 
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    Topics: Biology , Mathematics
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    Editorial: Viewpoint (1989)
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    Bulletin of mathematical biology 51 (1989), S. 415-415 
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    Stochastic models for subpopulation emergence in heterogeneous tumors (1989)
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    Bulletin of mathematical biology 51 (1989), S. 731-747 
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    Notes: Abstract A stochastic analog to a deterministic model describing subpopulation emergence in heterogeneous tumors is developed. The resulting system is described by the Fokker-Planck or forward Kolmogorov equation. A finite element approach for the numerical solution to this equation is described. Four biological and clinical scenarios are simulated (emergence of heterogeneity, exclusion of a subpopulation, and induction of drug resistance in both pure and heterogeneous tumors). The results of the simulations show that the stochastic model describes the same basic dynamics as its deterministic counterpart via a convective component, but that for each simulation a distribution of tumor sizes and mixes can also be derived from a diffusive component in the model. These distributions yield estimates for subpopulation extinction probabilities. The biological and clinical relevance of these results are discussed.
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    Algorithms for the optimal identification of segment neighborhoods (1989)
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    Bulletin of mathematical biology 51 (1989), S. 39-54 
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    ISSN: 1522-9602
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    Topics: Biology , Mathematics
    Notes: Abstract Two algorithms for the efficient identification of segment neighborhoods are presented. A segment neighborhood is a set of contiguous residues that share common features. Two procedures are developed to efficiently find estimates for the parameters of the model that describe these features and for the residues that define the boundaries of each segment neighborhood. The algorithms can accept nearly any model of segment neighborhood, and can be applied with a broad class of best fit functions including least squares and maximum likelihood. The algorithms successively identify the most important features of the sequence. The application of one of these methods to the haemagglutinin protein of influenza virus reveals a possible mechanism for conformational change through the finding of a break in a strong heptad repeat structure.
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    Approximate matching of regular expressions (1989)
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    Bulletin of mathematical biology 51 (1989), S. 5-37 
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    Notes: Abstract Given a sequenceA and regular expressionR, theapproximate regular expression matching problem is to find a sequence matchingR whose optimal alignment withA is the highest scoring of all such sequences. This paper develops an algorithm to solve the problem in timeO(MN), whereM andN are the lengths ofA andR. Thus, the time requirement is asymptotically no worse than for the simpler problem of aligning two fixed sequences. Our method is superior to an earlier algorithm by Wagner and Seiferas in several ways. First, it treats real-valued costs, in addition to integer costs, with no loss of asymptotic efficiency. Second, it requires onlyO(N) space to deliver just the score of the best alignment. Finally, its structure permits implementation techniques that make it extremely fast in practice. We extend the method to accommodate gap penalties, as required for typical applications in molecular biology, and further refine it to search for substrings ofA that strongly align with a sequence inR, as required for typical data base searches. We also show how to deliver an optimal alignment betweenA andR in onlyO(N+logM) space usingO(MN logM) time. Finally, anO(MN(M+N)+N 2logN) time algorithm is presented for alignment scoring schemes where the cost of a gap is an arbitrary increasing function of its length.
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    Codon preference and primary sequence structure in protein-coding regions (1989)
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    Bulletin of mathematical biology 51 (1989), S. 95-115 
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    Topics: Biology , Mathematics
    Notes: Abstract The stochastic complexity of a data base of 365 protein-coding regions is analysed. When the primary sequence is modeled as a spatially homogeneous Markov source, the fit to observed codon preference is very poor. The situation improves substantially when a non-homogeneous model is used. Some implications for the estimation of species phylogeny and substitution rates are discussed.
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    Tutorial on large deviations for the binomial distribution (1989)
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    Bulletin of mathematical biology 51 (1989), S. 125-131 
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    Notes: Abstract We present, in an easy to use form, the large deviation theory of the binomial distribution: how to approximate the probability ofk or more successes inn independent trials, each with success probabilityp, when the specified fraction of successes,a≡k/n, satisfies 0〈p〈a〈1.
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    Editorial: Software survey section (1989)
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    Bulletin of mathematical biology 51 (1989), S. I 
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    A continuous analog for RNA folding (1989)
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    Bulletin of mathematical biology 51 (1989), S. 167-171 
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    Notes: Abstract A linear segment in which a number of pairs of intervals of equal length are identified as potential stems is the subject of a folding problem analogous to inference of RNA secondary structure. A quantity of free energy (or equivalently, energy per unit length) is associated with each stem, and the various types of loops are assigned energy costs as a function of their lengths. Inference of stable structures can then be carried out in the same way as in RNA folding. More important, perturbation of stem lengths and energy densities (modelling various mutational processes affecting nucleotide sequences) allows the delineation of domains of stability of various foldings, through the explicit calculation of their boundaries, in a low-dimensional parameter space.
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    Prediction of linear and non-linear responses of MGB neurons by system identification methods (1989)
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    Bulletin of mathematical biology 51 (1989), S. 337-346 
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    ISSN: 1522-9602
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    Notes: Abstract In sensory physiology, various System Identification methods are implemented to formalized stimulus-response relationships. We applied the Volterra approach for characterizing input-output relationships of cells in the medial geniculate body (MGB) of an awake squirrel monkey. Intraspecific communication calls comprised the inputs and the corresponding cellular evoked responses—the outputs. A set of vocalization was used to calculate the kernels of the transformation, and these kernels subserved to predict the responses of the cell to a different set of vocalizations. It was found that it is possible to predict the response (PSTH) of MGB cells to natural vocalizations, based on envelopes of the spectral components of the vocalization. Some of the responses could be predicted by assuming a linear transformation function, whereas other responses could be predicted by non-linear (second order) kernels. These two modes of transformation, which are also reflected by a distinct spatial distribution of the linearvis-à-vis non-linear responding cells, apparently representa new revelation of parallel processing of auditory information.
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    Diffusion limited immunochemical sensing (1989)
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    Bulletin of mathematical biology 51 (1989), S. 359-379 
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    Notes: Abstract The time-dependent surface coverage of antigen-antibody complexes for a sensor in which antigens are bound to surface immobilized antibodies is determined analytically. Assuming a reversible first order reaction between the antigens and antibodies, a model is derived describing the dynamical response of the sensor. The surface coverage is related explicitly to the antigen concentration which is of special interest in experimental situations. The stationary state and short time behaviour are determined explicitly. Several illustrations of the full solution are provided.
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    An informational approach to reaction times (1989)
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    Bulletin of mathematical biology 51 (1989), S. 347-358 
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    Notes: Abstract Simple reaction time is the minimum time required to respond to a signal such as a steady light or tone. Such a reaction time is taken to be the time required for transmission of a fixed quantity of information, ΔH, from stimulus to subject. That is, information summation replaces energy summation. This information is calculated from consideration of the quantum nature of the stimulus. The theoretically derived equation for reaction time is fitted to experimental data. Piéron's empirical law for reaction time is obtained as an approximation from a proposed informational equation. The exponent in Piéron's law is found to be the same as the exponent in the power law of sensation. Threshold appears to be the smallest stimulus capable of transmitting the quantity of information ΔH.
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    The Third World Conference on Mathematics at the Service of Man (1989)
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    Bulletin of mathematical biology 51 (1989), S. 413-413 
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    Editorial: Software survey section (1989)
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    Bulletin of mathematical biology 51 (1989), S. I 
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    Design of FIR filters with reduced computations (1989)
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    Circuits, systems and signal processing 8 (1989), S. 17-23 
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    ISSN: 1531-5878
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology
    Notes: Abstract The performance of a symmetric nonrecursive filter can be improved by multiple use of the same filter. The method is based on an Amplitude Change Function (ACF). An approach to the design of nonrecursive filters using an ACF is discussed in this paper. The prototype filter chosen is a Recursive Running Sum (RRS) filter which does not require any multipliers for its implementation. The required filter specifications are met by multiple use of the RRS filters. The overall filter requires a much smaller number of multiplications and adders than the one designed using the conventional method. It is shown that this method provides reduced noise due to coefficient quantization and product quantization compared with the conventional design technique.
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    Statistical analysis of two nonlinear least-squares estimators of sine-wave parameters in the colored-noise case (1989)
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    Circuits, systems and signal processing 8 (1989), S. 3-15 
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    ISSN: 1531-5878
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology
    Notes: Abstract This paper establishes the large-sample accuracy properties of two nonlinear least-squares estimators (NLSE) of sine-wave parameters: the basic NLSE, which ignores the possible correlation of the noise, and the optimal NLSE, which, besides the sine-wave parameters, also estimates the noise correlation (appropriately parametrized). It is shown that these two NLS estimators have thesame accuracy in large samples. This result provides complete justification for preferring the computationally less expensive basic NLSE over the “optimal” NLSE. Both estimators are shown to achieve the Cramér-Rao Bound (CRB) as the sample size increases. A simple explicit expression for the CRB matrix is provided, which should be useful in studying the performance of sine-wave parameter estimators designed to work in the colored-noise case.
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    Synthesis of two-dimensional losslessm-Ports with prescribed scattering matrix (1989)
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    Circuits, systems and signal processing 8 (1989), S. 97-119 
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    ISSN: 1531-5878
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    Topics: Electrical Engineering, Measurement and Control Technology
    Notes: Abstract Multidimensional lossless networks are of special interest for use as reference structures for multidimensional wave digital filters [l]–[3]. The starting point of the presented synthesis procedure for two-dimensional representatives of the networks mentioned is a scattering matrix description of the desired multiport. This given matrix is assumed to have those properties which have turned out to be necessary [9], [10] for any scattering matrix of a multidimensional lossless network. The method presented for the synthesis of 2-D reactancem-ports is based mainly on known properties of block-companion matrices and the factorization of a univariable rational matrix which is discrete para-Hermitian and nonnegative definite on the unit circle. The resulting network always contains only a minimal number of frequency-dependent building elements. No restrictions are made concerning the coefficients of the rational entries of the scattering matrix; they may be either real or complex, so as to include even complex networks which are of special interest for multi-dimensional wave digital filters [3].
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    Systems which possessg- andh- Representations (1989)
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    Circuits, systems and signal processing 8 (1989), S. 145-162 
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    Topics: Electrical Engineering, Measurement and Control Technology
    Notes: Abstract Examples are given concerning the range of applicability of recent representation results that provide a means of studying the input-output properties of nonlinear systems in terms of the familiar impulse-response concept, and which extend the concept of integral transformation to nonlinear maps. We show that such representations, which we call “g-” and “h-representations,” exist for important classes of systems governed by nonlinear integral equations. In particular, it is proved that a large class of maps that have Volterra series representations also have these representations.
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    The alignment of protein structures in three dimensions (1989)
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    Bulletin of mathematical biology 51 (1989), S. 55-78 
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    ISSN: 1522-9602
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    Topics: Biology , Mathematics
    Notes: Abstract This article extends the use of dynamic programming algorithms in molecular sequence comparison to the alignment of the α-carbon (Cα-) coordinates of two protein structures in three dimensions. The algorithm is described in detail and is applied to the comparison of α-lactalbumin with both hen egg white lysozyme and T4 lysozyme. In the first case, the structures are similar, while the second comparison is between two distantly related molecules. References are made to the usual sequence alignments. A variety of complementary methods are introduced to display the results.
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    Stochastic models for heterogeneous DNA sequences (1989)
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    Bulletin of mathematical biology 51 (1989), S. 79-94 
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    Topics: Biology , Mathematics
    Notes: Abstract The composition of naturally occurring DNA sequences is often strikingly heterogeneous. In this paper, the DNA sequence is viewed as a stochastic process with local compositional properties determined by the states of a hidden Markov chain. The model used is a discrete-state, discreteoutcome version of a general model for non-stationary time series proposed by Kitagawa (1987). A smoothing algorithm is described which can be used to reconstruct the hidden process and produce graphic displays of the compositional structure of a sequence. The problem of parameter estimation is approached using likelihood methods and an EM algorithm for approximating the maximum likelihood estimate is derived. The methods are applied to sequences from yeast mitochondrial DNA, human and mouse mitochondrial DNAs, a human X chromosomal fragment and the complete genome of bacteriophage lambda.
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    Weak hierarchies associated with similarity measures—An additive clustering technique (1989)
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    Bulletin of mathematical biology 51 (1989), S. 133-166 
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    Topics: Biology , Mathematics
    Notes: Abstract A new and apparently rather useful and natural concept in cluster analysis is studied: given a similarity measure on a set of objects, a sub-set is regarded as a cluster if any two objectsa, b inside this sub-set have greater similarity than any third object outside has to at least one ofa, b. These clusters then form a closure system which can be described as a hypergraph without triangles. Conversely, given such a system, one may attach some weight to each cluster and then compose a similarity measure additively, by letting the similarity of a pair be the sum of weights of the clusters containing that particular pair. The original clusters can be reconstructed from the obtained similarity measure. This clustering model is thus located between the general additive clustering model of Shepard and Arabie (1979) and the standard hierarchical model. Potential applications include fitting dendrograms with few additional nonnested clusters and simultaneous representation of some families of multiple dendrograms (in particular, two-dendrogram solutions), as well as assisting the search for phylogenetic relationships by proposing a somewhat larger system of possibly relevant “family groups”, from which an appropriate choice (based on additional insight or individual preferences) remains to be made.
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    Computational experience with an algorithm for tetrangle inequality bound smoothing (1989)
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    Bulletin of mathematical biology 51 (1989), S. 173-194 
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    Topics: Biology , Mathematics
    Notes: Abstract An important component of computer programs for determining the solution conformation of proteins and other flexible molecules from nuclear magnetic resonance data are the so-called “bound smoothing algorithms”, which compute lower and upper limits on the values of all the interatomic distances from the relatively sparse set which can usually be measured experimentally. To date, the only methods efficient enough for use in large problems take account of only the triangle inequality, but an appreciable improvement in the precision of the limits is possible if the algebraic relations between the distances among each quadruple of atoms are also considered. The goal of this paper is to use a recently improved algorithm for computing these “tetrangle inequality limits” to determine just how much improvement really is possible, given the types of experimental data that are usually available.
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    Wavelength selection mechanism in the Gierer-Meinhardt model (1989)
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    Bulletin of mathematical biology 51 (1989), S. 207-216 
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    Notes: Abstract We apply the concept of marginal stability hypothesis, which has been proposed for solving the problem of dendritic crystal growth, to the pattern selection problem in the Gierer-Meinhardt models. In the case of a large system, the system selects a definite wavelength of the ultimate spatial pattern when the unstable homogeneous steady state is locally disturbed. The numerical results are analyzed theoretically by means of the marginal stability hypothesis, and they are in good agreement with it. Biologically, these results imply why for large systems the Gierer-Meinhardt model (and presumably other reaction-diffusion schemes) have the ability to explain the observation that pattern-generating mechanisms are remarkably insensitive to a wide range of environmental and experimental conditions.
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    Automata network theories in immunology: Their utility and their underdetermination (1989)
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    Bulletin of mathematical biology 51 (1989), S. 247-253 
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    Topics: Biology , Mathematics
    Notes: Abstract Small networks of threshold automata are used to model complex interactions between populations of regulatory cells (helpers and suppressors, antigen specific and anti-idiotypic) which participate in the immune response. The models, being discrete and semiquantitative, are well adapted to the situation of incomplete information often encounteredin vivo. However, the dynamics of many different network structures usually end up in the same attractor set. Thus, many different theories are equivalent in their explicative power for the same facts. This property, known as underdetermination of the theories by the facts, is given a quantitative estimate. It appears that such an underdetermination, as a kind of irreductible complexity, can be expected in manyin vivo biological processes, even when the number of interacting and functionally coupled elements is relatively small.
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    Resilience and local stability in a nutrient-limited resource-consumer system (1989)
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    Bulletin of mathematical biology 51 (1989), S. 501-510 
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    Topics: Biology , Mathematics
    Notes: Abstract The “paradox of enrichment” predicts that increasing the growth rate of the resource in a resource-consumer dynamic system, by nutrient enrichment, for example, can lead to local instability of the system—that is, to a Hopf bifurcation. The approach to the Hopf bifurcation is accompanied by a decrease in resilience (rate of return to equilibrium). On the other hand, studies of nutrient cycling in food webs indicate that an increase in the nutrient input rate usually results in increased resilience. Here these two apparently conflicting theoretical results are reconciled with a model of a nutrient-limited resource-consumer system in which the tightly recycled limiting nutrient is explicitly modelled. It is shown that increasing nutrient input may at first lead to increased resilience and that resilience decreases sharply only immediately before the Hopf bifurcation is reached.
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    Book reviews (1989)
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    Bulletin of mathematical biology 51 (1989), S. 537-544 
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    Centrifugal-order distributions in binary topological trees (1989)
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    Bulletin of mathematical biology 51 (1989), S. 511-536 
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    Notes: Abstract Statistical properties of topological binary trees are studied on the basis of the distribution of segments in relation to centrifugal order. Special attention is paid to the mean of this distribution in a tree as it will be used as a measure of tree topology. It will be shown how the expectation of the mean centrifugal order depends both on the size of the tree and on the mode of growth in the context of modelling the growth of tree structures. Observed trees can be characterized by their mean orders and procedures are described to find the growth mode that optimally corresponds to these data. The variance structure of the mean-order measure appears to be a crucial factor in these fitting procedures. Examples indicate that mean-order analysis is an accurate alternative to partition analysis that is based on the partitioning of segments over sub-tree pairs at branching points.
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    On limits to perception and pattern recognition (1989)
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    Bulletin of mathematical biology 51 (1989), S. 681-686 
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    Notes: Abstract We propose certain general conditions that we believe are reasonable for any pattern recognition algorithm. We find that these conditions give rise to paradoxical identification. The algorithms are incapable of distinguishing composite patterns and must be able to distinguish patterns at an atomistic level.
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    Microevolution in MioceneBrizalina (foraminifera) studied by canonical variate analysis and analysis of landmarks (1989)
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    Bulletin of mathematical biology 51 (1989), S. 657-679 
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    ISSN: 1522-9602
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    Notes: Abstract A stratigraphically oriented series of the Miocene foraminiferal speciesBrizalina mandoroveensis from Ikang, Cameroon, was analyzed both by conventional multivariate morphometric procedures and by the tensor biometric method of Bookstein (1986;Statist. Sci. 1, 181–142), a method which analyzes sets of landmark points rather than specific variables of shape or size. The conventional analysis used five size-measures upon 170 specimens from five stratigraphic levels; the tensor analysis encompassed six landmarks (12 coordinates) upon 50 specimens. Whereas certain features appeared in both analyses, such as the separation between levels one and five, the techniques did not always agree with respect to the interpretation of those findings or about most details in the sequence of mean phenotypes. The canonical variate analysis bases its ordination upon a general size factor (the meaning of which is obscured by the foreshortening of within-group variation which is built into the technique). The tensor analysis locates a similar ordination using mainly features of shape.
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    Analytic results for quantifying HIV infectivity (1989)
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    Bulletin of mathematical biology 51 (1989), S. 715-730 
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    Notes: Abstract In a separate paper, we developed a mathematical model describing HIV infection and used it to suggest experiments for quantifying characteristic viral parameters. In this paper we generalize the model to any well-mixed assay system. We also present complete and rigorous derivations of fundamental results needed for the design and analysis of HIV infectivity assays. The model is applicable to infectious agents with multiple receptors for their target cell (e.g. HIV, Epstein-Barr virus and Plasmodium), and to blockers (both reversible and irreversible), as long as blocker and target cells are the same diffusion compartment.
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    On Ebenman's model for the dynamics of a population with competing juveniles and adults (1989)
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    Bulletin of mathematical biology 51 (1989), S. 687-713 
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    Notes: Abstract A general version of a model of Ebenman for the dynamics of a population consisting of competing juveniles and adults is analyzed using methods of bifurcation theory. A very general existence results is obtained for non-trivial equilibria and non-negative synchronous two-cycles that bifurcate simultaneously at the critical valuer=1 of the inherent net reproductive rater. Stability is studied in this general setting near the bifurcation point and conditions are derived that determine which of these two bifurcating branches is the stable branch. These general results are supplemented by numerical studies of the asymptotic dynamics over wider parameter ranges where various other bifurcations and stable attractors are found. The implications of these results are discussed with respect to the effects on stability that age class competition within a population can have and whether such competition is stabilizing or destabilizing.
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    Phototransduction in cones: An inverse problem in enzyme kinetics (1989)
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    Bulletin of mathematical biology 51 (1989), S. 749-784 
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    Notes: Abstract Phototransduction is a process which links the absorption of photons by a rod or cone to the modulation of voltage across the cell membrane. An important feature of many vertebrate photoreceptors is a mechanism that adjusts the sensitivity and dynamics of the response to light according to the level of illumination. We construct a system of ordinary differential equations that models what are currently thought to be the important molecule mechanisms involved in phototransduction: this includes consideration of both intracellular enzyme kinetics and the properties of light-insensitive and light-sensitive conductances in the cone membrane. The system contains negative feedback whose functional form is determined by constraining the steady-state behaviour of the system. Despite the highly nonlinear nature of the system of ordinary differential equations, our methods permit us to derive an analytic expression for the first-order frequency response parametric in the steady-state value of only one dynamic variable, the light input. Various unknown kinetic parameters are found by fitting the model to experimental data on the first-order frequency response of cones measured at several mean light levels spanning a range of four log units. Good fits are obtained to the data, and the computed shape of the feedback function agrees qualitatively with recent experiment. Moreover, the model accounts for the dramatic speeding up of the response kinetics and the decrease in response gain with increasing light level.
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    Foreword (1989)
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    Bulletin of mathematical biology 51 (1989), S. 1-4 
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    Unreasonable implications of reasonable idiotypic network assumptions (1989)
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    Bulletin of mathematical biology 51 (1989), S. 381-408 
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    Notes: Abstract We first analyse a simple symmetric model of the idiotypic network. In the model idiotypic interactions regulate B cell proliferation. Three non-idiotypic processes are incorporated: (1) influx of newborn cells; (2) turnover of cells: (3) antigen. Antigen also regulates proliferation. A model of 2 B cell populations has 3 stable equilibria: one virgin, two immune. The twodimensional system thus remembers antigens, i.e. accounts for immunity. By contrast, if an idiotypic clone proliferates (in response to antigen), its anti-idiotypic partner is unable to control this. Symmetric idiotypic networks thus fail to account for proliferation regulation. In high-D networks we run into two problems. Firstly, if the network accounts for memory, idiotypic activation always propagates very deeply into the network. This is very unrealistic, but is an implication of the “realistic” assumption that it should be easier to activate all cells of a small virgin clone than to maintain the activation of all cells of a large (immune) clone. Secondly, graph theory teaches us that if the (random) network connectance exceeds a threshold level of one interaction per clone, most clones are interconnected. We show that this theory is also applicable to immune networks based on complementary matching idiotypes. The combination of the first “percolation” result with the “interconnectancr” result means that the first stimulation of the network with antigen should eventually affect most of the clones. We think this is unreasonable. Another threshold property of the network connectivity is the existence of a virgin state. A gradual increase in network connectance eliminates the virgin state and thus causes an abrupt change in network behaviour. In contrast to weakly connected systems, highly connected networks display autonomous activity and are unresponsive to external antigens. Similar differences between neonatal and adult networks have been described by experimentalists. The robustness of these results is tested with a network in which idiotypic inactivation of a clone occurs more generally than activation. Such “long-range inhibition” is known to promote pattern formation. However, in our model it fails to reduce the percolation, and additionally, generates semi-chaotic behaviour. In our network, the inhibition of a clone that is inhibiting can alter this clone into a clone that is activating. Hence “long-range inhibition” implies “long-range activation”, and idiotypic activation fails to remain localized. We next complicate this model by incorporating antibody production. Although this “antibody” model statically accounts for the same set of equilibrium points, it dynamically fails to account for state switching (i.e. memory). The switching behaviour is disturbed by the autonomous slow decay of the (long-lived) antibodies. After antigenic triggering the system now performs complex cyclic behaviour. Finally, it is suggested that (idiotypic) formation of antibody complexes can play only a secondary role in the network. In conclusion, our results cast doubt on the functional role of a profound idiotypic network. The network fails to account for proliferation regulation, and if it accounts for memory phenomena, it “explodes” upon the first encounter with antigen due to extensive percolation.
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    Description of the birch leaf roller's incisions for different leaves (1989)
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    Bulletin of mathematical biology 51 (1989), S. 433-447 
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    Notes: Abstract A new biomathematical description is given for the shape of the birch leaf roller's (Deporaus betulae) incisions. These incisions are investigated for different leaves. The theoretical patterns agree well with the real ones, and the presented mathematical expressions describe well the shape of the real incisions.
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    The multiple codes of nucleotide sequences (1989)
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    Bulletin of mathematical biology 51 (1989), S. 417-432 
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    Notes: Abstract Nucleotide sequences carry genetic information of many different kinds, not just instructions for protein synthesis (triplet code). Several codes of nucleotide sequences are discussed including: (1) the translation framing code, responsible for correct triplet counting by the ribosome during protein synthesis; (2) the chromatin code, which provides instructions on appropriate placement of nucleosomes along the DNA molecules and their spatial arrangement; (3) a putative loop code for single-stranded RNA-protein interactions. The codes are degenerate and corresponding messages are not only interspersed but actually overlap, so that some nucleotides belong to several messages simultaneously. Tandemly repeated sequences frequently considered as functionless “junk” are found to be grouped into certain classes of repeat unit lengths. This indicates some functional involvement of these sequences. A hypothesis is formulated according to which the tandem repeats are given the role of weak enhancer-silencers that modulate, in a copy number-dependent way, the expression of proximal genes. Fast amplification and elimination of the repeats provides an attractive mechanism of species adaptation to a rapidly changing environment.
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    Velocity distribution on the membrane of a tank-treading red blood cell (1989)
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    Bulletin of mathematical biology 51 (1989), S. 449-465 
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    Notes: Abstract The kinematics of an area-conserving tank-treading disk-shaped red blood cell membrane is studied using the stream function method suggested by Secomb and Skalak (Q. Jl Mech. appl. Math. 35, Pt 2, 233–247, 1982). Two simple area-conserving velocity fields are superimposed to satisfy the continuity condition at the curved edges of the disk. A differential equation for the trajectory of any material point of the membrane is derived. The requirement of synchrony of the cycle for all membrane points leads to an integral equation which determines a magnitude function. An approximate solution is made possible by assuming small trajectory deflections.
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    Mathematical formulation and studies of the risk parameters involved in HIV transmission (1989)
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    Bulletin of mathematical biology 51 (1989), S. 467-474 
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    Notes: Abstract The probability of becoming infected with HIV is formulated in terms of the total number of sexual contacts (N), the probability that a sexual act is infectious (r) and the prevalence (p). Using the appropriate equations we studied the effect of reducing each of the risk factors on lowering the probability of infection. We show that for many realistic situations the probability of becoming infected by multiple partners is equal to the probability of becoming infected by one partner in a monogamous relationship given that the prevalence is the same in both cases; however if the multiple partners are chosen over time from a pool of a growing prevalence, then one is better off in a monogamous relationship where that partner is chosen early in the epidemic.
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    An optimal algorithm to reconstruct trees from additive distance data (1989)
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    Bulletin of mathematical biology 51 (1989), S. 597-603 
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    Notes: Abstract In this article the question of reconstructing a phylogeny from additive distance data is addressed. Previous algorithms used the complete distance matrix of then OTUs (Operational Taxonomic Unit), that corresponds to the tips of the tree. This usedO(n 2) computing time. It is shown that this is wasteful for biologically reasonable trees. If the tree has internal nodes with degrees that are bounded onO(n*log(n)) algorithm is possible. It is also shown if the nodes can have unbounded degrees the problem hasn 2 as lower bound.
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    Editorial: Software survey section (1989)
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    Bulletin of mathematical biology 51 (1989), S. I 
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    Electronic Resource
    Temporal properties of some biological systems and their fractal attractors (1989)
    Springer
    Bulletin of mathematical biology 51 (1989), S. 785-800 
    Details
    ISSN: 1522-9602
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Mathematics
    Notes: Abstract In this paper we analyse time series data as the growth of organisms using markers such as treerings and otolith deposits (fish). The series studied belong to two tree species (Pinus uncinata, Fagus sylvatica) and one fish species (Dicentrarchus labrax). Spectral analyses of the time series growth show that the main frequencies of fluctuation may be due to variations of the energy input. However, any causal explanation must consider the internal continuous readjustment in the system as reported by the corresponding chaotic properties of the asymptotic decay of the spectra time structure. Since the output of noisy and chaotic systems tend to show similar spectral densities, an attempt to differentiate them has been carried out. The chaotic behaviour has been characterized by the study of the attractors. The dimmensions of these multiple topologies were 3.2 and 3.4 for the tree species and 2.3 for the fish species. Therefore, we are dealing with fractal attractors and the minimum number of variables that can be used to describe the systems are 4 and 3 respectively. It is suggested that some of the variables that most influence growth are those obtained by the response functions in the case of trees.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02459660
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  • 95
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    Context-dependent associations in linear distributed memories (1989)
    Springer
    Bulletin of mathematical biology 51 (1989), S. 195-205 
    Details
    ISSN: 1522-9602
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Mathematics
    Notes: Abstract In this article we present a method that allows conditioning of the response of a linear distributed memory to a variable context. This method requires a system of two neural networks. The first net constructs the Kronecker product between the vector input and the vector context, and the second net supports a linear associative memory. This system is easily adaptable for different goals. We analyse here its capacity for the conditional extraction of features from a complex perceptual input, its capacity to perform quasi-logical operations (for instance, of the kind of “exclusive-or”), and its capacity to structurate a memory for temporal sequences which access is conditioned by the context. Finally, we evaluate the potential importance of the capacity to establish arbitrary contexts, for the evolution of biological cognitive systems.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02458441
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  • 96
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    Stability of symmetric idiotypic networks—a critique of Hoffmann's analysis (1989)
    Springer
    Bulletin of mathematical biology 51 (1989), S. 217-222 
    Details
    ISSN: 1522-9602
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Mathematics
    Notes: Abstract Hoffmann (1982) analysed a very simple model of suppressive idiotypic immune networks and showed that idiotypic interactions are stabilizing. He concluded that immune networks provide a counterexample to the general analysis of large dynamic systems (Gardner and Ashby, 1970; May, 1972). The latter is often verbalized as: an increase in size and/or connectivity decreases the system stability. We here analyse this apparent contradiction by extending the Hoffmann model (with a decay term), and comparing it to an ecological model that was used as a paradigm in the general analysis. Our analysis confirms that the neighbourhood stability of such idiotypic networks increases with connectivity and/or size. However, the contradiction is one of interpretation, and is not due to exceptional properties of immune networks. The contradiction is caused by the awkward normalization used in the general analysis.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02458443
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  • 97
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    An alternative procedure for calculating glucose consumption from 2-deoxyglucose uptake (1989)
    Springer
    Bulletin of mathematical biology 51 (1989), S. 275-286 
    Details
    ISSN: 1522-9602
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Mathematics
    Notes: Abstract In the commonly used model (Sokoloff) for the transport and metabolism of glucose and 2-deoxyglucose in brain tissue a novel choice of constant parameters is proposed. In particular, the maximal transport capacity for glucose is assumed proportional to the rate of glucose consumption. The proportionality factor, the “transport factor”, may be calculated from the lumped constant and is more likely than the latter to remain constant under varying conditions. Calculations founded on these considerations should yield results similar to the Sokoloff procedure in many situations, but differences appear when the arterial glucose concentration changes. The model is flexible and allows changes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02458447
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  • 98
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    Electronic Resource
    Analysis of metabolic systems with complex slow and fast dynamics (1989)
    Springer
    Bulletin of mathematical biology 51 (1989), S. 255-274 
    Details
    ISSN: 1522-9602
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Mathematics
    Notes: Abstract We briefly review the results of other authors concerning the analysis of systems with time hierarchy, especially the Tikhonov theorem. A theorem, recently proved by the authors, making possible rigorous analysis of systems with complex fast dynamics is stated and discussed. A model example of a simple enzymatic reaction with product activation and slow (genetically driven) enzyme turnover is rigorously studied. It is shown that even in such a simple model there exist certain regions of parameters for which fast variables oscillate. Thus the classical Tikhonov theorem is not applicable here and we are forced to use another method-for example the author's presented theorem—or a purely numerical solution. These two methods are compared.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02458446
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  • 99
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    Analysis of interaction for mixtures of agents using the linear isobole (1989)
    Springer
    Bulletin of mathematical biology 51 (1989), S. 293-309 
    Details
    ISSN: 1522-9602
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Mathematics
    Notes: Abstract The linear isobole that is commonly used as a reference for the study of interaction is derived from the interaction of an agent with itself. It is shown that the general use of the linear isobole in the study of the combined effects of mixtures of agents implies interaction between the agents whether the dose-effect curves of the agents are the same or not. It is difficult to generalize the interaction between two doses of the same agent to the interaction between two doses of different agents with different action mechanisms without the use of a mechanistic model. Predictions using non-interaction defined as independent action are generally different from those using linear isobole. A simple mechanistic framework based on the concept of common intermediate lesions is introduced in this paper to relate these two methods used for the analysis of synergism and antagonism. In this framework of lesion development, two agents that have no common intermediate lesion in their action will be non-interactive (referred to as independent action). When the two agents share a common intermediate, it is shown that the combined effect will follow the linear isobole (referred to as common action). This simple framework of analysis is applicable to the general study of interaction between two agents with different types of dose-effect curves.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02460109
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  • 100
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    The pseudorandom sequence of arrays (1989)
    Springer
    Circuits, systems and signal processing 8 (1989), S. 133-144 
    Details
    ISSN: 1531-5878
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology
    Notes: Abstract Pseudorandom (or maximal length) sequences and arrays have been known for a long time, and have been reported by several authors. Pseudorandom volumes have also been mentioned. This paper presents a different type of sequence of arrays in which the arrays share many properties with the pseudorandom arrays of the literature, and the sequence (or group) of arrays has many properties in common with the pseudorandom sequences. It is proposed that this set of arrays be called a “pseudorandom sequence of arrays,” or PRSAs. Some interesting properties of the PRSA as well as its practical (hardware) implementation have been mentioned. It has also been shown that our result is a special case of the generalN(3)/D(3) case.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01599934
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