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  • 1
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    Chapter 4: Methodology and methods for the study of change in hydrology and society (2023)
    In:  XXVIII General Assembly of the International Union of Geodesy and Geophysics (IUGG)
    Details
    Publication Date: 2023-07-11
    Description: In this chapter, we review a variety of methods and modelling approaches employed in Panta Rhei and detail how each approach highlights different aspects, and how they can be brought together to advance a more holistic understanding of a human-water system. Change in coupled human-water systems has been studied using a wide variety of methods, before and during the Panta Rhei decade. We engage with the literature on the methods that have been developed by the Panta Rhei community over recent years while placing them in the wider context of existing research approaches for exploring change in human-water systems and settings used by other social and natural science fields. Going deeper into the methods, we present an overview of qualitative and quantitative methods, including modeling approaches, upon which we highlight the potential of mixed methods in studying human-water systems.
    Language: English
    Type: info:eu-repo/semantics/conferenceObject
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  • 2
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    Kinetics of sickle cell biorheology and implications for painful vasoocclusive crisis (2015)
    National Academy of Sciences
    Details
    Publication Date: 2015-01-20
    Description: We developed a microfluidics-based model to quantify cell-level processes modulating the pathophysiology of sickle cell disease (SCD). This in vitro model enabled quantitative investigations of the kinetics of cell sickling, unsickling, and cell rheology. We created short-term and long-term hypoxic conditions to simulate normal and retarded transit scenarios in microvasculature. Using blood samples from 25 SCD patients with sickle hemoglobin (HbS) levels varying from 64 to 90.1%, we investigated how cell biophysical alterations during blood flow correlated with hematological parameters, HbS level, and hydroxyurea (HU) therapy. From these measurements, we identified two severe cases of SCD that were also independently validated as severe from a genotype-based disease severity classification. These results point to the potential of this method as a diagnostic indicator of disease severity. In addition, we investigated the role of cell density in the kinetics of cell sickling. We observed an effect of HU therapy mainly in relatively dense cell populations, and that the sickled fraction increased with cell density. These results lend support to the possibility that the microfluidic platform developed here offers a unique and quantitative approach to assess the kinetic, rheological, and hematological factors involved in vasoocclusive events associated with SCD and to develop alternative diagnostic tools for disease severity to supplement other methods. Such insights may also lead to a better understanding of the pathogenic basis and mechanism of drug response in SCD.
    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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  • 3
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    Cellular normoxic biophysical markers of hydroxyurea treatment in sickle cell disease (2016)
    National Academy of Sciences
    Details
    Publication Date: 2016-08-10
    Description: Hydroxyurea (HU) has been used clinically to reduce the frequency of painful crisis and the need for blood transfusion in sickle cell disease (SCD) patients. However, the mechanisms underlying such beneficial effects of HU treatment are still not fully understood. Studies have indicated a weak correlation between clinical outcome and molecular markers, and the scientific quest to develop companion biophysical markers have mostly targeted studies of blood properties under hypoxia. Using a common-path interferometric technique, we measure biomechanical and morphological properties of individual red blood cells in SCD patients as a function of cell density, and investigate the correlation of these biophysical properties with drug intake as well as other clinically measured parameters. Our results show that patient-specific HU effects on the cellular biophysical properties are detectable at normoxia, and that these properties are strongly correlated with the clinically measured mean cellular volume rather than fetal hemoglobin level.
    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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  • 4
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    Rise and fall of nitrogen deposition in the US [Physical Sciences] (2016)
    National Academy of Sciences
    Details
    Publication Date: 2016-06-30
    Description: Understanding the changes in rates and composition of nitrogen (N) deposition has important implications for the regulation of anthropogenic N emissions and is a prerequisite for the assessment of the consequent ecological impacts. By comparing observed data on wet deposition between the periods 1990–1992 and 2010–2012, Li et al. (1)...
    Keywords: Letters
    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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  • 5
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    Winter soil respiration during soil-freezing process in a boreal forest in Northeast China (2013)
    Oxford University Press
    Details
    Publication Date: 2013-09-21
    Description: Aims Boreal forest is the largest and contains the most soil carbon among global terrestrial biomes. Soil respiration during the prolonged winter period may play an important role in the carbon cycles in boreal forests. This study aims to explore the characteristics of winter soil respiration in the boreal forest and to show how it is regulated by environmental factors, such as soil temperature, soil moisture and snowpack. Methods Soil respiration in an old-growth larch forest ( Larix gmelinii Ruppr.) in Northeast China was intensively measured during the winter soil-freezing process in 2011 using an automated soil CO 2 flux system. The effects of soil temperature, soil moisture and thin snowpack on soil respiration and its temperature sensitivity were investigated. Important Findings Total soil respiration and heterotrophic respiration both showed a declining trend during the observation period, and no significant difference was found between soil respiration and heterotrophic respiration until the snowpack exceeded 20cm. Soil respiration was exponentially correlated with soil temperature and its temperature sensitivity (Q 10 value) for the entire measurement duration was 10.5. Snow depth and soil moisture both showed positive effects on the temperature sensitivity of soil respiration. Based on the change in the Q 10 value, we proposed a ‘freeze–thaw critical point’ hypothesis, which states that the Q 10 value above freeze–thaw critical point is much higher than that below it (16.0 vs . 3.5), and this was probably regulated by the abrupt change in soil water availability during the soil-freezing process. Our findings suggest interactive effects of multiple environmental factors on winter soil respiration and recommend adopting the freeze–thaw critical point to model soil respiration in a changing winter climate.
    Print ISSN: 1752-993X
    Electronic ISSN: 1752-9921
    Topics: Biology
    Published by Oxford University Press
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  • 6
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    Temperature and substrate availability regulate soil respiration in the tropical mountain rainforests, Hainan Island, China (2013)
    Oxford University Press
    Details
    Publication Date: 2013-09-21
    Description: Aims Tropical forest plays a key role in global C cycle; however, there are few studies on the C budget in the tropical rainforests in Asia. This study aims to (i) reveal the seasonal patterns of total soil respiration ( R T ), litter respiration ( R L ) and soil respiration without surface organic litter ( R NL ) in the primary and secondary Asian tropical mountain rainforests and (ii) quantify the effects of soil temperature, soil moisture and substrate availability on soil respiration. Methods The seasonal dynamics of soil CO 2 efflux was measured by an automatic chamber system (Li-8100), within the primary and secondary tropical mountain rainforests located at the Jianfengling National Reserve in Hainan Island, China. The litter removal treatment was used to assess the contribution of litter to belowground CO 2 production. Important Findings The annual R T was higher in the primary forest (16.73±0.87 Mg C ha –1 ) than in the secondary forest (15.10±0.26 Mg C ha –1 ). The rates of R T , R NL and R L were all significantly higher in the hot and wet season (May–October) than those in the cool and dry season (November–April). Soil temperature at 5cm depth could explain 55–61% of the seasonal variation in R T , and the temperature sensitivity index ( Q 10 ) ranked by R L ( Q 10 = 3.39) 〉 R T (2.17) 〉 R NL (1.76) in the primary forest and by R L (4.31) 〉 R T (1.86) 〉 R NL (1.58) in the secondary forest. The contribution of R L to R T was 22–23%, while litter input and R T had 1 month time lag. In addition, the seasonal variation of R T was mainly determined by soil temperature and substrate availability. Our findings suggested that global warming and increased substrate availability are likely to cause considerable losses of soil C in the tropical forests.
    Print ISSN: 1752-993X
    Electronic ISSN: 1752-9921
    Topics: Biology
    Published by Oxford University Press
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  • 7
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    NEECF: a project of nutrient enrichment experiments in China's forests (2013)
    Oxford University Press
    Details
    Publication Date: 2013-09-21
    Description: Anthropogenic nitrogen (N) emissions to atmosphere have increased dramatically in China since 1980s, and this increase has aroused great concerns on its ecological impacts on terrestrial ecosystems. Previous studies have showed that terrestrial ecosystems in China are acting as a large carbon (C) sink, but its potential in the future remains largely uncertain. So far little work on the impacts of the N deposition on C sequestration in China’s terrestrial ecosystems has been assessed at a national scale. Aiming to assess and predict how ecological processes especially the C cycling respond to the increasing N deposition in China’s forests, recently researchers from Peking University and their partners have established a manipulation experimental network on the ecological effects of the N deposition: Nutrient Enrichment Experiments in China’s Forests Project (NEECF). The NEECF comprises 10 experiments at 7 sites located from north to south China, covering major zonal forest vegetation in eastern China from boreal forest in Greater Khingan Mountains to tropical forests in Hainan Island. This paper introduces the framework of the NEECF project and its potential policy implications.
    Print ISSN: 1752-993X
    Electronic ISSN: 1752-9921
    Topics: Biology
    Published by Oxford University Press
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  • 8
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    Rapid Characterization of Water Diffusion in Polymer Specimens Using a Droplet-Based Method (2020)
    American Chemical Society
    Details
    Publication Date: 2020-06-05
    Print ISSN: 0743-7463
    Electronic ISSN: 1520-5827
    Topics: Chemistry and Pharmacology
    Published by American Chemical Society
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  • 9
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    Microfluidic pumping optimization in microgrooved channels with ac electrothermal actuations (2010)
    American Institute of Physics
    Details
    Publication Date: 2010-01-18
    Print ISSN: 0003-6951
    Electronic ISSN: 1077-3118
    Topics: Physics
    Published by American Institute of Physics
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  • 10
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    Mechanical fatigue of human red blood cells (2019)
    National Academy of Sciences
    Details
    Publication Date: 2019-09-16
    Description: Fatigue arising from cyclic straining is a key factor in the degradation of properties of engineered materials and structures. Fatigue can also induce damage and fracture in natural biomaterials, such as bone, and in synthetic biomaterials used in implant devices. However, the mechanisms by which mechanical fatigue leads to deterioration of physical properties and contributes to the onset and progression of pathological states in biological cells have hitherto not been systematically explored. Here we present a general method that employs amplitude-modulated electrodeformation and microfluidics for characterizing mechanical fatigue in single biological cells. This method is capable of subjecting cells to static loads for prolonged periods of time or to large numbers of controlled mechanical fatigue cycles. We apply the method to measure the systematic changes in morphological and biomechanical characteristics of healthy human red blood cells (RBCs) and their membrane mechanical properties. Under constant amplitude cyclic tensile deformation, RBCs progressively lose their ability to stretch with increasing fatigue cycles. Our results further indicate that loss of deformability of RBCs during cyclic deformation is much faster than that under static deformation at the same maximum load over the same accumulated loading time. Such fatigue-induced deformability loss is more pronounced at higher amplitudes of cyclic deformation. These results uniquely establish the important role of mechanical fatigue in influencing physical properties of biological cells. They further provide insights into the accumulated membrane damage during blood circulation, paving the way for further investigations of the eventual failure of RBCs causing hemolysis in various hemolytic pathologies.
    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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