1,303 research outputs found
Complexity, Collective Effects and Modelling of Ecosystems: formation, function and stability
We discuss the relevance of studying ecology within the framework of
Complexity Science from a statistical mechanics approach. Ecology is concerned
with understanding how systems level properties emerge out of the multitude of
interactions amongst large numbers of components, leading to ecosystems that
possess the prototypical characteristics of complex systems. We argue that
statistical mechanics is at present the best methodology available to obtain a
quantitative description of complex systems, and that ecology is in urgent need
of ``integrative'' approaches that are quantitative and non-stationary. We
describe examples where combining statistical mechanics and ecology has led to
improved ecological modelling and, at the same time, broadened the scope of
statistical mechanics.Comment: 11 pages and 1 figur
Mucosal unresponsiveness to aflatoxin B1 is not broken by cholera toxin
Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/142024/1/imcb19978.pd
Automatic transmission: ethnicity, racialization and the car
YesThis article is based on ethnographic research carried out in Bradford, an ethnically diverse city situated in the north of England. The sample of over 60 participants mostly comprises males of British Pakistani Muslim heritage but varies in terms other markers of identity such as social class, profession and residential/working locale. The article analyses the cultural value and meaning of cars within a multicultural context and how a consumer object can feed into the processes which refine and embed racialized identities. Small cases studies reveal the concrete and discursive ways through which ideas around identity and ethnicity are transmitted and how, in particular, racialization continues to feature as a live, active and recognisable process in everyday experience
MINERvA neutrino detector response measured with test beam data
The MINERvA collaboration operated a scaled-down replica of the solid
scintillator tracking and sampling calorimeter regions of the MINERvA detector
in a hadron test beam at the Fermilab Test Beam Facility. This article reports
measurements with samples of protons, pions, and electrons from 0.35 to 2.0
GeV/c momentum. The calorimetric response to protons, pions, and electrons are
obtained from these data. A measurement of the parameter in Birks' law and an
estimate of the tracking efficiency are extracted from the proton sample.
Overall the data are well described by a Geant4-based Monte Carlo simulation of
the detector and particle interactions with agreements better than 4%, though
some features of the data are not precisely modeled. These measurements are
used to tune the MINERvA detector simulation and evaluate systematic
uncertainties in support of the MINERvA neutrino cross section measurement
program.Comment: as accepted by NIM
Ethnicity and consumption: South Asian food shopping patterns in Britain 1947-75
Authors' draft version also available on University of Surrey e-print repository. Final version published by Sage and available at http://joc.sagepub.com/This article reviews the literature that explores the relationship between ethnic
identities and food consumption, with particular reference to business management
studies. It focuses on the food shopping practices of south Asians in Britain in the
period 1947 to 1975, to illustrate the need for more historically contextualized studies
that can provide a more nuanced exploration of any interconnections between ethnic
identity and shopping behaviour. The article draws on a reasonably long-standing
interest in ethnicity and consumption in marketing studies, and explores the
conceptual use of acculturation within this literature. The arguments put forward are
framed by recent interdisciplinary studies of the broader relationship between
consumption and identity, which stress the importance of contextualizing any
influence of ethnic identifications through a wider consideration of other factors
including societal status, gender and age, rather than giving it singular treatment. The
article uses a body of empirical research drawn from recent oral histories, to explore
how these factors informed everyday shopping practices among south Asians in Britain. It examines some of the shopping and wider food provisioning strategies
adopted by early immigrants on arrival in Britain. It considers the interaction between
the south Asian population and the changing retail structure, in the context of the
development of self-service and the supermarket. Finally, it demonstrates how age,
gender and socioeconomic status interacted with ethnic identities to produce
variations in shopping patterns
Comparing nuclear power trajectories in Germany and the UK: from âregimes' to âdemocraciesâ in sociotechnical transitions and Discontinuities
This paper focuses on arguably the single most striking contrast in contemporary major energy politics in Europe (and even the developed world as a whole): the starkly differing civil nuclear policies of Germany and the UK. Germany is seeking entirely to phase out nuclear power by 2022. Yet the UK advocates a ânuclear renaissanceâ, promoting the most ambitious new nuclear construction programme in Western Europe.Here,this paper poses a simple yet quite fundamental question: what are the particular divergent conditions most strongly implicated in the contrasting developments in these two countries. With nuclear playing such an iconic role in historical discussions over technological continuity and transformation, answering this may assist in wider understandings of sociotechnical incumbency and discontinuity in the burgeoning field ofâsustainability transitionsâ. To this end, an âabductiveâ approach is taken: deploying nine potentially relevant criteria for understanding the different directions pursued in Germany and the UK. Together constituted by 30 parameters spanning literatures related to socio-technical regimes in general as well as nuclear technology in particular, the criteria are divided into those that are âinternalâ and âexternalâ to the âfocal regime configurationâ of nuclear power and associated âchallenger technologiesâ like renewables.
It is âinternalâ criteria that are emphasised in conventional sociotechnical regime theory, with âexternalâ criteria relatively less well explored. Asking under each criterion whether attempted discontinuation of nuclear power would be more likely in Germany or the UK, a clear picture emerges. âInternalâ criteria suggest attempted nuclear discontinuation should be more likely in the UK than in Germanyâ the reverse of what is occurring.
âExternalâ criteria are more aligned with observed dynamics âespecially those relating to military nuclear commitments and broader âqualities of democracyâ. Despite many differences of framing concerning exactly what constitutes âdemocracyâ, a rich political science literature on this point is unanimous in characterising Germany more positively than the UK. Although based only on a single case,a potentially important question is nonetheless raised as to whether sociotechnical regime theory might usefully give greater attention to the general importance of various aspects of democracy in constituting conditions for significant technological discontinuities and transformations. If so, the policy implications are significant. A number of important areas are identified for future research, including the roles of diverse understandings and specific aspects of democracy and the particular relevance of military nuclear commitmentsâ whose under-discussion in civil nuclear policy literatures raises its own questions of democratic accountability
Continuous production of xylooligosaccharides in a packed bed reactor with immobilizedâstabilized biocatalysts of xylanase from Aspergillus versicolor
Selenium supplementation acting through the induction of thioredoxin reductase and glutathione peroxidase protects the human endothelial cell line EAhy926 from damage by lipid hydroperoxides
AbstractThe human endothelial cell line EAhy926 was used to determine the importance of selenium in preventing oxidative damage induced by tert-butyl hydroperoxide (tert-BuOOH) or oxidised low density lipoprotein (LDLox). In cells grown in a low selenium medium, tert-BuOOH and LDLox killed cells in a dose-dependent manner. At 555 mg/l LDLox or 300 ÎŒM tert-BuOOH, >80% of cells were killed after 20 h. No significant cell kill was achieved by these agents if cells were pre-incubated for 48 h with 40 nM sodium selenite, a concentration that maximally induced the activities of cytoplasmic glutathione peroxidase (cyGPX; 5.1-fold), phospholipid hydroperoxide glutathione peroxidase (PHGPX;1.9-fold) and thioredoxin reductase (TR; 3.1-fold). Selenium-deficient cells pre-treated with 1 ÎŒM gold thioglucose (GTG) (a concentration that inhibited 25% of TR activity but had no inhibitory effect on cyGPX or PHGPX activity) were significantly (P<0.05) more susceptible to tert-BuOOH toxicity (LC50 110 ÎŒM) than selenium-deficient cells (LC50 175 ÎŒM). This was also the case for LDLox. In contrast, cells pre-treated with 40 nM selenite prior to exposure to GTG were significantly more resistant to damage from tert-BuOOH and LDLox than Se-deficient cells. Treatment with GTG or selenite had no significant effect on intracellular total glutathione concentrations. These results suggest that selenium supplementation, acting through induction of TR and GPX, has the potential to protect the human endothelium from oxidative damage
A Novel Assay to Trace Proliferation History In Vivo Reveals that Enhanced Divisional Kinetics Accompany Loss of Hematopoietic Stem Cell Self-Renewal
BACKGROUND: The maintenance of lifelong blood cell production ultimately rests on rare hematopoietic stem cells (HSCs) that reside in the bone marrow microenvironment. HSCs are traditionally viewed as mitotically quiescent relative to their committed progeny. However, traditional techniques for assessing proliferation activity in vivo, such as measurement of BrdU uptake, are incompatible with preservation of cellular viability. Previous studies of HSC proliferation kinetics in vivo have therefore precluded direct functional evaluation of multi-potency and self-renewal, the hallmark properties of HSCs. METHODOLOGY/PRINCIPAL FINDINGS: We developed a non-invasive labeling technique that allowed us to identify and isolate candidate HSCs and early hematopoietic progenitor cells based on their differential in vivo proliferation kinetics. Such cells were functionally evaluated for their abilities to multi-lineage reconstitute myeloablated hosts. CONCLUSIONS: Although at least a few HSC divisions per se did not influence HSC function, enhanced kinetics of divisional activity in steady state preceded the phenotypic changes that accompanied loss of HSC self-renewal. Therefore, mitotic quiescence of HSCs, relative to their committed progeny, is key to maintain the unique functional and molecular properties of HSCs
An Integrated TCGA Pan-Cancer Clinical Data Resource to Drive High-Quality Survival Outcome Analytics
For a decade, The Cancer Genome Atlas (TCGA) program collected clinicopathologic annotation data along with multi-platform molecular profiles of more than 11,000 human tumors across 33 different cancer types. TCGA clinical data contain key features representing the democratized nature of the data collection process. To ensure proper use of this large clinical dataset associated with genomic features, we developed a standardized dataset named the TCGA Pan-Cancer Clinical Data Resource (TCGA-CDR), which includes four major clinical outcome endpoints. In addition to detailing major challenges and statistical limitations encountered during the effort of integrating the acquired clinical data, we present a summary that includes endpoint usage recommendations for each cancer type. These TCGA-CDR findings appear to be consistent with cancer genomics studies independent of the TCGA effort and provide opportunities for investigating cancer biology using clinical correlates at an unprecedented scale. Analysis of clinicopathologic annotations for over 11,000 cancer patients in the TCGA program leads to the generation of TCGA Clinical Data Resource, which provides recommendations of clinical outcome endpoint usage for 33 cancer types
- âŠ