1,069 research outputs found
Explaining Showering: a Discussion of the Material, Conventional, and Temporal Dimensions of Practice
This article considers the increasing popularity of showering in the UK. We use this case as a means of exploring some of the dimensions and dynamics of everyday practice. Drawing upon a range of documentary evidence, we begin by sketching three possible explanations for the current constitution of showering as a private, increasingly resource-intensive routine. We begin by reviewing the changing infrastructural, technological, rhetorical and moral positioning of showering. We then consider how the multiple and contingent constituents of showering are arranged and re-arranged in and through the practice itself. In taking this approach, we address a number of more abstract questions about the relation between practices, technologies and infrastructures and about what these relationships mean for the fixity and fluidity of ordinary routines and for associated patterns of consumption. The result is a method that allows us to analyze the ways in which material cultures and conventions are reproduced and transformed. This has practical implications for those seeking to contain the environmental consequences of resource-intensive practices.Xx
Imprint of DESI fiber assignment on the anisotropic power spectrum of emission line galaxies
The Dark Energy Spectroscopic Instrument (DESI), a multiplexed fiber-fed
spectrograph, is a Stage-IV ground-based dark energy experiment aiming to
measure redshifts for 29 million Emission-Line Galaxies (ELG), 4 million
Luminous Red Galaxies (LRG), and 2 million Quasi-Stellar Objects (QSO). The
survey design includes a pattern of tiling on the sky and the locations of the
fiber positioners in the focal plane of the telescope, with the observation
strategy determined by a fiber assignment algorithm that optimizes the
allocation of fibers to targets. This strategy allows a given region to be
covered on average five times for a five-year survey, but with coverage varying
between zero and twelve, which imprints a spatially-dependent pattern on the
galaxy clustering. We investigate the systematic effects of the fiber
assignment coverage on the anisotropic galaxy clustering of ELGs and show that,
in the absence of any corrections, it leads to discrepancies of order ten
percent on large scales for the power spectrum multipoles. We introduce a
method where objects in a random catalog are assigned a coverage, and the mean
density is separately computed for each coverage factor. We show that this
method reduces, but does not eliminate the effect. We next investigate the
angular dependence of the contaminated signal, arguing that it is mostly
localized to purely transverse modes. We demonstrate that the cleanest way to
remove the contaminating signal is to perform an analysis of the anisotropic
power spectrum and remove the lowest bin, leaving
modes accurate at the few-percent level. Here, is the cosine of the angle
between the line-of-sight and the direction of . We also investigate
two alternative definitions of the random catalog and show they are comparable
but less effective than the coverage randoms method.Comment: Submitted to JCA
A New Approach to Lower Dimensional Gauge Theories
We apply the method of differential renormalization to two and three
dimensional abelian gauge theories. The method is especially well suited for
these theories as the problems of defining the antisymmetric tensor are avoided
and the calculus involved is impressively simple. The topological and dynamical
photon masses are obtained.Comment: 8 pag. in Late
Intelligent Agents for Disaster Management
ALADDIN [1] is a multi-disciplinary project that is developing novel techniques, architectures, and mechanisms for multi-agent systems in uncertain and dynamic environments. The application focus of the project is disaster management. Research within a number of themes is being pursued and this is considering different aspects of the interaction between autonomous agents and the decentralised system architectures that support those interactions. The aim of the research is to contribute to building more robust multi-agent systems for future applications in disaster management and other similar domains
Interpretation of electron-proton scattering at low Q^2
Low-Q^2 photons do not resolve partons in the proton, which gives problems
when applying the deep inelastic scattering formalism, such as an unphysical,
negative gluon density extracted from data. Considering instead hadronic
fluctuations of the photon, we show that the generalised vector meson dominance
model (GVDM) gives a good description of the measured cross section at low Q^2,
i.e. reproduces F_2(x,Q^2), using only few parameters with essentially known
values. Combining GVDM and parton density functions makes it possible to obtain
a good description of F_2 data over the whole range of x and Q^2.Comment: 10 pages, 3 figures. Discussion extended, references added, figures
updated with additional results. Accepted for publication in Physics Letters
On the regularization scheme and gauge choice ambiguities in topologically massive gauge theories
It is demonstrated that in the (2+1)-dimensional topologically massive gauge
theories an agreement of the Pauli-Villars regularization scheme with the other
schemes can be achieved by employing pairs of auxiliary fermions with the
opposite sign masses. This approach does not introduce additional violation of
discrete (P and T) symmetries. Although it breaks the local gauge symmetry only
in the regulator fields' sector, its trace disappears completely after removing
the regularization as a result of superrenormalizability of the model. It is
shown also that analogous extension of the Pauli-Villars regularization in the
vector particle sector can be used to agree the arbitrary covariant gauge
results with the Landau ones. The source of ambiguities in the covariant gauges
is studied in detail. It is demonstrated that in gauges that are softer in the
infrared region (e.g. Coulomb or axial) nonphysical ambiguities inherent to the
covariant gauges do not arise.Comment: Latex, 13 pages. Replaced mainly to change preprint references to
journal one
Trehalose Transporter from African Chironomid Larvae Improves Desiccation Tolerance of Chinese Hamster Ovary Cells
Dry preservation has been explored as an energy-efficient alternative to cryopreservation, but the high sensitivity of mammalian cells to desiccation stress has been one of the major hurdles in storing cells in the desiccated state. An important strategy to reduce desiccation sensitivity involves use of the disaccharide trehalose. Trehalose is known to improve desiccation tolerance in mammalian cells when present on both sides of the cell membrane. Because trehalose is membrane impermeant the development of desiccation strategies involving this promising sugar is hindered. We explored the potential of using a high-capacity trehalose transporter (TRET1) from the African chironomid Polypedilum vanderplanki[21] to introduce trehalose into the cytoplasm of mammalian cells and thereby increase desiccation tolerance. When Chinese hamster ovary cells (CHO) were stably transfected with TRET1 (CHO-TRET1 cells) and incubated with 0.4M trehalose for 4h at 37°C, a sevenfold increase in trehalose uptake was observed compared to the wild-type CHO cells. Following trehalose loading, desiccation tolerance was investigated by evaporative drying of cells at 14% relative humidity. After desiccation to 2.60g of water per gram dry weight, a 170% increase in viability and a 400% increase in growth (after 7days) was observed for CHO-TRET1 relative to control CHO cells. Our results demonstrate the beneficial effect of intracellular trehalose for imparting tolerance to partial desiccation
High-throughput single cell arrays as a novel tool in biopreservation
Microwell array cytometry is a novel high-throughput experimental technique that makes it possible to correlate pre-stress cell phenotypes and post-stress outcomes with single cell resolution. Because the cells are seeded in a high density grid of cell-sized microwells, thousands of individual cells can be tracked and imaged through manipulations as extreme as freezing or drying. Unlike flow cytometry, measurements can be made at multiple time points for the same set of cells. Unlike conventional image cytometry, image analysis is greatly simplified by arranging the cells in a spatially defined pattern and physically separating them from one another. To demonstrate the utility of microwell array cytometry in the field of biopreservation, we have used it to investigate the role of mitochondrial membrane potential in the cryopreservation of primary hepatocytes. Even with optimized cryopreservation protocols, the stress of freezing almost always leads to dysfunction or death in part of the cell population. To a large extent, cell fate is dominated by the stochastic nature of ice crystal nucleation, membrane rupture, and other biophysical processes, but natural variation in the initial cell population almost certainly plays an important and under-studied role. Understanding why some cells in a population are more likely to survive preservation will be invaluable for the development of new approaches to improve preservation yields. For this paper, primary hepatocytes were seeded in microwell array devices, imaged using the mitochondrial dyes Rh123 or JC-1, cryopreserved for up to a week, rapidly thawed, and checked for viability after a short recovery period. Cells with a high mitochondrial membrane potential before freezing were significantly less likely to survive the freezing process, though the difference in short term viability was fairly small. The results demonstrate that intrinsic cell factors do play an important role in cryopreservation survival, even in the short term where extrinsic biophysical factors would be expected to dominate. We believe that microwell array cytometry will be an important tool for a wide range of studies in biopreservation and stress biology. © 2009 Elsevier Inc. All rights reserved
J/psi Inclusive Production in nu N Neutral-Current Deep-Inelastic Scattering
We calculate the cross section of J/psi inclusive production in
neutrino-nucleon deep-inelastic scattering via the weak neutral current within
the factorization formalism of nonrelativistic quantum chromodynamics. Besides
J/psi single production via the Z-gluon fusion mechanism, we also consider
J/psi plus hadron-jet associated production. We take into account both direct
production and feed-down from directly-produced heavier charmonia. We present
theoretical predictions for the J/psi transverse-momentum and rapidity
distributions, which can be measured in the CHORUS and NOMAD experiments at
CERN, including conservative error estimates. In order to interpret a recent
CHORUS measurement of the total cross section, we also estimate the
contribution due to J/psi prompt production via diffractive processes using the
vector-meson dominance model.Comment: 34 pages (Latex), 5 figures (Postscript); significantly extended to
include feed-down and diffractive contributions and nuclear corrections;
accepted for publication in Nucl. Phys.
Premenopausal endogenous oestrogen levels and breast cancer risk: a meta-analysis.
BACKGROUND: Many of the established risk factors for breast cancer implicate circulating hormone levels in the aetiology of the disease. Increased levels of postmenopausal endogenous oestradiol (E2) have been found to increase the risk of breast cancer, but no such association has been confirmed in premenopausal women. We carried out a meta-analysis to summarise the available evidence in women before the menopause. METHODS: We identified seven prospective studies of premenopausal endogenous E2 and breast cancer risk, including 693 breast cancer cases. From each study we extracted odds ratios of breast cancer between quantiles of endogenous E2, or for unit or s.d. increases in (log transformed) E2, or (where odds ratios were unavailable) summary statistics for the distributions of E2 in breast cancer cases and unaffected controls. Estimates for a doubling of endogenous E2 were obtained from these extracted estimates, and random-effect meta-analysis was used to obtain a pooled estimate across the studies. RESULTS: Overall, we found weak evidence of a positive association between circulating E2 levels and the risk of breast cancer, with a doubling of E2 associated with an odds ratio of 1.10 (95% CI: 0.96, 1.27). CONCLUSION: Our findings are consistent with the hypothesis of a positive association between premenopausal endogenous E2 and breast cancer risk
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