University of California, Irvine

About: University of California, Irvine is a education organization based out in Irvine, California, United States. It is known for research contribution in the topics: Population & Galaxy. The organization has 47031 authors who have published 113602 publications receiving 5521832 citations. The organization is also known as: UC Irvine & UCI.

Airborne Particulate Matter and Human Health: A Review

Abstract: Results of recent research show that particulate matter (PM) composition and size vary widely with both space and time. Despite the variability in PM characteristics, which are believed to influence human health risks, the observed relative health risk estimates per unit PM mass falls within a narrow range of values. Furthermore, no single chemical species appears to dominate health effects; rather the effects appear to be due to a combination of species. Non-PM factors such as socioeconomic status and lifestyle are also believed to affect the health risk, although accounting for these confounding factors is challenging. Airborne PM is also responsible for a number of effects aside from human health, such as alterations in visibility and climate. Because the PM problem is associated with a range of societal issues such as energy production and economic development, making progress on reducing the effects of PM will require integrated strategies that bring together scientists and decision makers from diffe...

Mass balance of the Antarctic ice sheet from 1992 to 2017.

Abstract: The Antarctic Ice Sheet is an important indicator of climate change and driver of sea-level rise. Here we combine satellite observations of its changing volume, flow and gravitational attraction with modelling of its surface mass balance to show that it lost 2,720 ± 1,390 billion tonnes of ice between 1992 and 2017, which corresponds to an increase in mean sea level of 7.6 ± 3.9 millimetres (errors are one standard deviation). Over this period, ocean-driven melting has caused rates of ice loss from West Antarctica to increase from 53 ± 29 billion to 159 ± 26 billion tonnes per year; ice-shelf collapse has increased the rate of ice loss from the Antarctic Peninsula from 7 ± 13 billion to 33 ± 16 billion tonnes per year. We find large variations in and among model estimates of surface mass balance and glacial isostatic adjustment for East Antarctica, with its average rate of mass gain over the period 1992–2017 (5 ± 46 billion tonnes per year) being the least certain.

Structure‐Activity Analyses of β‐Amyloid Peptides: Contributions of the β25–35 Region to Aggregation and Neurotoxicity

Abstract: The neurodegeneration of Alzheimer's disease has been theorized to be mediated, at least in part, by insoluble aggregates of beta-amyloid protein that are widely distributed in the form of plaques throughout brain regions affected by the disease. Previous studies by our laboratory and others have demonstrated that the neurotoxicity of beta-amyloid in vitro is dependent upon its spontaneous adoption of an aggregated structure. In this study, we report extensive structure-activity analyses of a series of peptides derived from both the proposed active fragment of beta-amyloid, beta 25-35, and the full-length protein, beta 1-42. We examine the effects of amino acid residue deletions and substitutions on the ability of beta-amyloid peptides to both form sedimentable aggregates and induce toxicity in cultured hippocampal neurons. We observe that significant levels of peptide aggregation are always associated with significant beta-amyloid-induced neurotoxicity. Further, both N- and C-terminal regions of beta 25-35 appear to contribute to these processes. In particular, significant disruption of peptide aggregation and toxicity result from alterations in the beta 33-35 region. In beta 1-42 peptides, aggregation disruption is evidenced by changes in both electrophoresis profiles and fibril morphology visualized at the light and electron microscope levels. Using circular dichroism analysis in a subset of peptides, we observed classic features of beta-sheet secondary structure in aggregating, toxic beta-amyloid peptides but not in nonaggregating, nontoxic beta-amyloid peptides. Together, these data further define the primary and secondary structures of beta-amyloid that are involved in its in vitro assembly into neurotoxic peptide aggregates and may underlie both its pathological deposition and subsequent degenerative effects in Alzheimer's disease.

Coupling biogeochemical cycles in urban environments: ecosystem services, green solutions, and misconceptions

Abstract: Urban green space is purported to offset greenhouse-gas (GHG) emissions, remove air and water pollutants, cool local climate, and improve public health. To use these services, municipalities have focused efforts on designing and implementing ecosystem-services-based “green infrastructure” in urban environments. In some cases the environmental benefits of this infrastructure have been well documented, but they are often unclear, unquantified, and/or outweighed by potential costs. Quantifying biogeochemical processes in urban green infrastructure can improve our understanding of urban ecosystem services and disservices (negative or unintended consequences) resulting from designed urban green spaces. Here we propose a framework to integrate biogeochemical processes into designing, implementing, and evaluating the net effectiveness of green infrastructure, and provide examples for GHG mitigation, stormwater runoff mitigation, and improvements in air quality and health.

A resource‐based approach to the multibusiness firm: Empirical analysis of portfolio interrelationships and corporate financial performance

Abstract: The resource-based view of the firm has provided important new insights into corporate strategy (Barney, 1991; Peteraf, 1993); however, there has been only limited empirical research linked to the theory (e.g., Farjoun, 1994). Although a great deal of work has been done on Corporate diversification, the measures and data typically have a weak connection to resource-based theory. Empirical research on resource-based corporate strategy has been particularly dificult because key concepts such as tacit knowledge or capabilities resist direct measurement. This study is an effort to narrow the gap between theory and empirical research on the multibusiness firm. It develops a resource-based approach to modeling interrelationships among businesses and applies it to the analysis of corporate economic performance. This approach proves to be significant in explaining the financial performance of large manufacturing firms, and it promises to be an important source of insight into corporate strategy.