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  • 1
    Electronic Resource
    Electronic Resource
    On Stephany's theory of origin of 1/f bulk noise (1994)
    Springer
    Il nuovo cimento della Società Italiana di Fisica 16 (1994), S. 537-541 
    Details
    ISSN: 0392-6737
    Keywords: Noise processes and phenomena
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Summary Stephany's treatment is not correct since he neglects the friction force proportional to the velocity, which we show to be universal,i.e. present in any mechanism of electric conduction. Moreover his predicted power spectral density is in some cases three orders of magnitude larger than the observed one. Finally, his noise cannot be the true 1/f noise because it should predict a low cut-off of ∼5·10−2 Hz due to the transit time of the electron-linked lattice (ELL) carriers through a distance of 20 μm while no cut-off has been observed down to 10−3 Hz.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02451652
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Fokker-Planck equation and relevant Chapman-Cowling-Davydov expression modified for coulomb scattering (1993)
    Springer
    Il nuovo cimento della Società Italiana di Fisica 15 (1993), S. 1301-1314 
    Details
    ISSN: 0392-6737
    Keywords: Transport properties ; Low-field and Townsend discharges ; Transport processes: theory
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Summary TheP 1 approximation to the Boltzmann equation in the case of slightly ionized gases leads to the usual Fokker-Planck equation whose solution in steady-state condition is the Chapman-Cowling-Davydov (CCD) expression. We have extended the same procedure to include electron-ion interactions when the corresponding collision frequency is of the same order of, or larger than, the electron-neutral molecule collision frequency. We have considered a case where, after an initial ionization of a column of gas, the majority of the electrons have diffused to, and have been captured by, the walls of the chamber so that we may neglect the electron-electron interactions. We have found a modified CCD expression. However, numerical calculations show that the differences between the modified expressions and the standard ones in which the electron-ion collision frequency for momentum transfer is added to the electron-neutral collision frequency are beyond the present experimental accuracy.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02463830
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  • 3
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    The buried caldera boundary of the Vesuvius 1631 eruption revealed by present-day soil CO2 concentration (2019)
    Details
    Publication Date: 2021-07-14
    Description: Volcanic risk at Vesuvius is one of the highest in the world due to the ~670,000 inhabitants living in the Red Zone, the area exposed to both pyroclastic flows and tephra fallout, to be evacuated before renewal of any eruptive activity. The national emergency plan for Vesuvius builds its risk zonation on a scenario similar to the last sub-Plinian eruption, which occurred in 1631. This study aims at providing new insights on the geometry of the caldera associated with this historical eruption. The impact of past Vesuvius eruptions on present-day soil CO2 concentration has been investigated by means of an extended geochemical survey carried out for identifying the circulation pathways of hydrothermal fluids inside the volcano. We performed 4,018 soil CO2 concentration measurements over the whole Somma-Vesuvius volcanic complex, covering an area of 50 km2. Besides relatively low values, the results show a significant spatial CO2 concentration heterogeneity over Somma-Vesuvius ranging from the atmospheric value (~400 ppm) up to ~24,140 ppm. The summit of Vesuvius shows an area with anomalous CO2 concentrations well matching the crater rim of the 1906 eruption. Along the cone flanks, secondary CO2 anomalies highlight a roughly circular preferential pathway detected along 8 radial profiles at distances between ~840 m and ~1,150 m from the bottom of the present-day crater resulting from the last eruption in 1944. In depth review of the available literature highlights an agreement between this circle-like shaped anomaly and the 1631 sub-Plinian eruption caldera boundary. Indeed, based on the historical chronicles the depression produced by the 1631 eruption had a diameter of 1,686 m, whereas the CO2 circular anomaly indicates a diameter of 1,956 m. Finally, the results were compared with a 3-D density model obtained from a recent gravity survey that corroborates both the literature and the CO2 data in terms of potential buried structure at the base of the Vesuvius cone.
    Description: Published
    Description: 43-56
    Description: 1V. Storia eruttiva
    Description: JCR Journal
    Keywords: Somma-Vesuvius ; soil CO2 concentration ; 1631 sub-Plinian eruption. ; carbon dioxide ; caldera. ; 04.08. Volcanology
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 4
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    Toward continuous 4D microgravity monitoring of volcanoes (2008)
    Society of Exploration Geophysicists
    Details
    Publication Date: 2017-04-04
    Description: Four-dimensional or time-lapse microgravity monitoring has been used effectively on volcanoes for decades to characterize the changes in subsurface volcanic systems. With measurements typically lasting from a few days to weeks and then repeated a year later, the spatial resolution of theses studies is often at the expense of temporal resolution and vice versa. Continuous gravity studies with one to two instruments operating for a short period of time (weeks to months) have shown enticing evidence of very rapid changes in the volcanic plumbing system (minutes to hours) and in one case precursory signals leading to eruptive activity were detected. The need for true multi-instrument networks is clear if we are to have both the temporal and spatial resolution needed for effective volcano monitoring. However, the high cost of these instruments is currently limiting the implementation of continuous microgravity networks. An interim approach to consider is the development of a collaborative network of researchers able to bring multiple instruments together at key volcanoes to investigate multitemporal physical changes in a few type volcanoes. However, to truly move forward, it is imperative that new low-cost instruments are developed to increase the number of instruments available at a single site. Only in this way can both the temporal and spatial integrity of monitoring be maintained. Integration of these instruments into a multiparameter network of continuously recording sensors is essential for effective volcano monitoring and hazard mitigation.
    Description: Published
    Description: WA19-WA28
    Description: 3.6. Fisica del vulcanismo
    Description: JCR Journal
    Description: reserved
    Keywords: gravity changes ; volcano ; 04. Solid Earth::04.01. Earth Interior::04.01.02. Geological and geophysical evidences of deep processes ; 04. Solid Earth::04.03. Geodesy::04.03.05. Gravity variations ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 5
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    CAPRI: efficient inference of cancer progression models from cross-sectional data (2015)
    Oxford University Press
    Details
    Publication Date: 2015-09-11
    Description: : We devise a novel inference algorithm to effectively solve the cancer progression model reconstruction problem. Our empirical analysis of the accuracy and convergence rate of our algorithm, CAncer PRogression Inference (CAPRI), shows that it outperforms the state-of-the-art algorithms addressing similar problems. Motivation: Several cancer-related genomic data have become available (e.g. The Cancer Genome Atlas , TCGA) typically involving hundreds of patients. At present, most of these data are aggregated in a cross-sectional fashion providing all measurements at the time of diagnosis. Our goal is to infer cancer ‘progression’ models from such data. These models are represented as directed acyclic graphs (DAGs) of collections of ‘selectivity’ relations, where a mutation in a gene A ‘selects’ for a later mutation in a gene B. Gaining insight into the structure of such progressions has the potential to improve both the stratification of patients and personalized therapy choices. Results: The CAPRI algorithm relies on a scoring method based on a probabilistic theory developed by Suppes, coupled with bootstrap and maximum likelihood inference. The resulting algorithm is efficient, achieves high accuracy and has good complexity, also, in terms of convergence properties. CAPRI performs especially well in the presence of noise in the data, and with limited sample sizes. Moreover CAPRI, in contrast to other approaches, robustly reconstructs different types of confluent trajectories despite irregularities in the data. We also report on an ongoing investigation using CAPRI to study atypical Chronic Myeloid Leukemia , in which we uncovered non trivial selectivity relations and exclusivity patterns among key genomic events. Availability and implementation: CAPRI is part of the TRanslational ONCOlogy R package and is freely available on the web at: http://bimib.disco.unimib.it/index.php/Tronco Contact: daniele.ramazzotti@disco.unimib.it Supplementary information: Supplementary data are available at Bioinformatics online.
    Print ISSN: 1367-4803
    Electronic ISSN: 1460-2059
    Topics: Biology , Computer Science , Medicine
    Published by Oxford University Press
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  • 6
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    Algorithmic methods to infer cancer progression [Biophysics and Computational Biology] (2016)
    National Academy of Sciences
    Details
    Publication Date: 2016-07-13
    Description: The genomic evolution inherent to cancer relates directly to a renewed focus on the voluminous next-generation sequencing data and machine learning for the inference of explanatory models of how the (epi)genomic events are choreographed in cancer initiation and development. However, despite the increasing availability of multiple additional -omics data, this...
    Print ISSN: 0027-8424
    Electronic ISSN: 1091-6490
    Topics: Biology , Medicine , Natural Sciences in General
    Published by National Academy of Sciences
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  • 7
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    Element flux to the environment of the passively degassing crater lake-hosting Kawah Ijen volcano, Indonesia, and implications for estimates of the global volcanic flux (2015)
    Geological Society (of London)
    Details
    Publication Date: 2015-12-19
    Description: Volcanoes play an important role in the global cycling of elements by providing a pathway from the deep Earth to its surface. Here, we have constrained the flux to the environment for most elements of the periodic table for the passively degassing, crater lake-hosting Kawah Ijen volcano in the Indonesian arc. Our results indicate that emissions of Kawah Ijen are dominated by acid water outflow, especially for the ligands (Cl, F, Br), with active fumaroles contributing significant (semi)metals (e.g. Se, As, Sb, Hg), as well as C and S. The compositional signature of emissions from Kawah Ijen is similar to that of major volcanic emitters such as Etna, but element fluxes are smaller. This result provides the prerequisite foundation for extrapolating a small set of measured volcanic gas emissions to a global volcanic flux estimate. However, the aqueous flux (i.e. seepage of volcanic hydrothermal fluids and volcano-influenced groundwater) is at least as important in terms of element release, and the consideration of the gaseous flux alone thus represents a significant underestimate of the impact of volcanoes on their environment and the contribution of volcanic hydrothermal systems to global element cycling. Supplementary material: The full datasets of water and fumarole gas chemical analyses are available at https://doi.org/10.6084/m9.figshare.c.2134359
    Print ISSN: 0305-8719
    Electronic ISSN: 2041-4927
    Topics: Geosciences
    Published by Geological Society (of London)
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  • 8
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    TRONCO: an R package for the inference of cancer progression models from heterogeneous genomic data (2016)
    Oxford University Press
    Details
    Publication Date: 2016-06-16
    Description: Motivation: We introduce TRanslational ONCOlogy (TRONCO), an open-source R package that implements the state-of-the-art algorithms for the inference of cancer progression models from (epi)genomic mutational profiles. TRONCO can be used to extract population-level models describing the trends of accumulation of alterations in a cohort of cross-sectional samples, e.g. retrieved from publicly available databases, and individual-level models that reveal the clonal evolutionary history in single cancer patients, when multiple samples, e.g. multiple biopsies or single-cell sequencing data, are available. The resulting models can provide key hints for uncovering the evolutionary trajectories of cancer, especially for precision medicine or personalized therapy. Availability and implementation: TRONCO is released under the GPL license, is hosted at http://bimib.disco.unimib.it/ (Software section) and archived also at bioconductor.org. Contact: tronco@disco.unimib.it Supplementary information: Supplementary data are available at Bioinformatics online.
    Print ISSN: 1367-4803
    Electronic ISSN: 1460-2059
    Topics: Biology , Computer Science , Medicine
    Published by Oxford University Press
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  • 9
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    GESTODIFFERENT: a Cytoscape plugin for the generation and the identification of gene regulatory networks describing a stochastic cell differentiation process (2013)
    Oxford University Press
    Details
    Publication Date: 2013-02-13
    Description: : The characterization of the complex phenomenon of cell differentiation is a key goal of both systems and computational biology. G e S to D ifferent is a Cytoscape plugin aimed at the generation and the identification of gene regulatory networks (GRNs) describing an arbitrary stochastic cell differentiation process. The (dynamical) model adopted to describe general GRNs is that of noisy random Boolean networks (NRBNs), with a specific focus on their emergent dynamical behavior. G e S to D ifferent explores the space of GRNs by filtering the NRBN instances inconsistent with a stochastic lineage differentiation tree representing the cell lineages that can be obtained by following the fate of a stem cell descendant. Matched networks can then be analyzed by Cytoscape network analysis algorithms or, for instance, used to define (multiscale) models of cellular dynamics. Availability: Freely available at http://bimib.disco.unimib.it/index.php/Retronet#GESTODifferent or at the Cytoscape App Store http://apps.cytoscape.org/ . Contact: marco.antoniotti@unimib.it
    Print ISSN: 1367-4803
    Electronic ISSN: 1460-2059
    Topics: Biology , Computer Science , Medicine
    Published by Oxford University Press
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  • 10
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    New insights into the Kawah Ijen hydrothermal system from geophysical data (2016)
    Geological Society (of London)
    Details
    Publication Date: 2016-01-24
    Description: The magmatic–hydrothermal system of Kawah Ijen volcano is one of the most exotic on Earth, featuring the largest acidic lake on the planet, a hyper-acidic river and a passively degassing silicic dome. While previous studies have mostly described this unique system from a geochemical perspective, to date there has been no comprehensive geophysical investigation of the system. In our study, we surveyed the lake using a thermocouple, a thermal camera, an echo sounder and CO 2 sensors. Furthermore, we gained insights into the hydrogeological structures by combining self-potential surveys with ground and water temperatures. Our results show that the hydrothermal system is self-sealed within the upper edifice and releases pressurized gas only through the active crater. We also show that the extensive hydrological system is formed by not one but three aquifers: a south aquifer that seems to be completely isolated, a west aquifer that sustains the acidic upper springs, and an east aquifer that is the main source of fresh water for the lake. In contrast with previous research, we emphasize the heterogeneity of the acidic lake, illustrated by intense subaqueous degassing. These findings provide new insights into this unique, hazardous hydrothermal system, which may eventually improve the existing monitoring system.
    Print ISSN: 0305-8719
    Electronic ISSN: 2041-4927
    Topics: Geosciences
    Published by Geological Society (of London)
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