1,804 research outputs found
The expected background spectrum in NaI dark matter detectors and the DAMA result
Detailed Monte Carlo simulations of the expected radioactive background rates
and spectra in NaI crystals are presented. The obtained spectra are then
compared to those measured in the DAMA/NaI and DAMA/LIBRA experiments. The
simulations can be made consistent with the measured DAMA spectrum only by
assuming higher than reported concentrations of some isotopes and even so leave
very little room for the dark matter signal. We conclude that any
interpretation of the annual modulation of the event rate observed by DAMA as a
dark matter signal, should include full consideration of the background
spectrum. This would significantly restrict the range of dark matter models
capable of explaining the modulation effect.Comment: 17 pages, 6 figure
Retrograde transport pathways utilised by viruses and protein toxins
A model has been presented for retrograde transport of certain toxins and viruses from the cell surface to the ER that suggests an obligatory interaction with a glycolipid receptor at the cell surface. Here we review studies on the ER trafficking cholera toxin, Shiga and Shiga-like toxins, Pseudomonas exotoxin A and ricin, and compare the retrograde routes followed by these protein toxins to those of the ER trafficking SV40 and polyoma viruses. We conclude that there is in fact no obligatory requirement for a glycolipid receptor, nor even with a protein receptor in a lipid-rich environment. Emerging data suggests instead that there is no common pathway utilised for retrograde transport by all of these pathogens, the choice of route being determined by the particular receptor utilised
The Supersymmetric Origin of Matter
The Minimal Supersymmetric extension of the Standard Model (MSSM) can provide
the correct neutralino relic abundance and baryon number asymmetry of the
universe. Both may be efficiently generated in the presence of CP violating
phases, light charginos and neutralinos, and a light top squark. Due to the
coannihilation of the neutralino with the light stop, we find a large region of
parameter space in which the neutralino relic density is consistent with WMAP
and SDSS data. We perform a detailed study of the additional constraints
induced when CP violating phases, consistent with the ones required for
baryogenesis, are included. We explore the possible tests of this scenario from
present and future electron Electric Dipole Moment (EDM) measurements, direct
neutralino detection experiments, collider searches and the b -> s gamma decay
rate. We find that the EDM constraints are quite severe and that electron EDM
experiments, together with stop searches at the Tevatron and Higgs searches at
the LHC, will provide a definite test of our scenario of electroweak
baryogenesis in the next few years.Comment: 30 pages, 14 figure
The DRIFT Project: Searching for WIMPS with a Directional Detector
A low pressure time projection chamber for the detection of WIMPs is
discussed. Discrimination against Compton electron background in such a device
should be very good, and directional information about the recoil atoms would
be obtainable. If a full 3-D reconstruction of the recoil tracks can be
achieved, Monte Carlo studies indicate that a WIMP signal could be identified
with high confidence from as few as 30 detected WIMP-nucleus scattering events.Comment: 5 pages, 3 figures. Presented at Dark 98, Heidelberg, July 1998, and
to appear in conference proceeding
Attitudes of Canadian Beef Producers Toward Animal Welfare
Commercial beef production in western Canada involves raising cows and calves on large tracts of grassland, plus grain-based ‘finishing’ of animals in outdoor feedlots. This study used open-ended, semi-structured interviews to explore views on animal welfare of 23 commercial beef producers in this system. Although wary of the term ‘animal welfare’, participants understood the concept to encompass three well-known elements: (i) basic animal health and body condition; (ii) affective states (comfort, contentment, freedom from hunger or thirst); and (iii) the ability to live a ‘natural’ life. Participants attached importance to protecting animals from natural hardships (extreme weather, predators), yet many regarded some degree of natural challenge as acceptable or even positive. Quiet rumination was uniformly regarded as indicating contentment. Avoiding ‘stress’ was seen as a central goal, to be achieved especially by skilful handling and good facilities. Invasive procedures (branding, castration, de-horning) were recognised as painful but were accepted because they were seen as: (i) necessary for regulatory or management reasons; (ii) satisfactory trade-offs to prevent worse welfare problems such as aggression; or (iii) sufficiently short-term to be relatively unimportant. Other issues — including poor facilities, rough or excessive handling, poor nutrition, and failure to protect health — were regarded as more serious welfare concerns. While feeling constrained by low profits, participants saw good welfare as crucial to profitability. Participants uniformly expressed an ethic of care, enjoyment of working with animals, and varying degrees of willingness to sacrifice personal comfort for animal well-being. We argue that animal welfare policy and advocacy are likely to be more successful in engaging producers if they acknowledge and address producers’ views on animal welfare
Novel Nonlinear Neural-Network Layers for High Performance and Generalization in Modulation-Recognition Applications
The paper presents a novel type of capsule network (CAP) that uses
custom-defined neural network (NN) layers for blind classification of digitally
modulated signals using their in-phase/quadrature (I/Q) components. The custom
NN layers of the CAP are inspired by cyclostationary signal processing (CSP)
techniques and implement feature extraction capabilities that are akin to the
calculation of the cyclic cumulant (CC) features employed in conventional
CSP-based approaches to blind modulation classification and signal
identification. The classification performance and the generalization abilities
of the proposed CAP are tested using two distinct datasets that contain similar
classes of digitally modulated signals but that have been generated
independently, and numerical results obtained reveal that the proposed CAP with
novel NN feature extraction layers achieves high classification accuracy while
also outperforming alternative deep learning (DL)-based approaches for signal
classification in terms of both classification accuracy and generalization
abilities.Comment: 6 pages, 7 figures, to be published in IEEE MILCOM 2023: IEEE
Military Communications Conference 2023. arXiv admin note: text overlap with
arXiv:2211.0023
Longitudinal patterns in an Arkansas River Valley stream: an Application of the River Continuum Concept
The River Continuum Concept (RCC) provides the framework for studying how lotic ecosystems vary from headwater streams to large rivers. The RCC was developed in streams in eastern deciduous forests of North America, but watershed characteristics and land uses differ across ecoregions, presenting unique opportunities to study how predictions of the RCC may differ across regions. Additionally, RCC predictions may vary due to the influence of fishes, but few studies have used fish taxa as a metric for evaluating predictions of the RCC. Our goal was to determine if RCC predictions for stream orders 1 through 5 were supported by primary producer, macroinvertebrate, and fish communities in Cadron Creek of the Arkansas River Valley. We sampled chlorophyll a, macroinvertebrates, and fishes at five stream reaches across a gradient of watershed size. Contrary to RCC predictions, chlorophyll a did not increase in concentration with catchment size. As the RCC predicts, fish and macroinvertebrate diversity increased with catchment size. Shredding and collecting macroinvertebrate taxa supported RCC predictions, respectively decreasing and increasing in composition as catchment area increased. Herbivorous and predaceous fish did not follow RCC predictions; however, surface-water column feeding fish were abundant at all sites as predicted. We hypothesize some predictions of the RCC were not supported in headwater reaches of this system due to regional differences in watershed characteristics and altered resource availability due to land use surrounding sampling sites
Readability and content analysis of lifestyle education resources for weight management in Australian general practice
© 2016 El-Haddad et al. Background: Weight management education is one of the key strategies to assist patients to manage their weight. Educational resources provide an important adjunct in the chain of communication between practitioners and patients. However, one in five Australian adults has low health literacy. The purpose of this study was to assess the readability and analyse the content of weight management resources. Methods: This study is based on the analysis of 23 resources found in the waiting rooms of ten Sydney-based general practices and downloaded from two clinical software packages used at these practices. The reading grade level of these resources was calculated using the Flesch Reading Ease, Flesch-Kincaid Grade Level, Fry Readability Graph, and the Simplified Measure of Gobbledygook. Resources' content was analysed for the presence of dietary, physical activity, and behaviour change elements, as recommended by the Clinical practice guidelines for the management of overweight and obesity in adults, adolescents, and children in Australia. Results: The resources' average reading grade level was for a 10th grader (9.5 ± 1.8). These findings highlight that the average reading grade level was two grades higher than the recommended reading grade level for health education resources of 8th grade level or below. Seventy percent of resources contained dietary and behaviour change elements. Physical activity was included in half of the resources. Two messages were identified to be inconsistent with the guidelines and three messages had no scientific basis. Conclusion: A body of evidence now exists that supports the need to develop evidence-based education resources for weight management that place low demand on literacy, without compromising content accuracy. The findings from this study suggest that there is significant room for improvement in the educational resources provided in general practices
Cytosolic chaperones influence the fate of a toxin dislocated from the endoplasmic reticulum
The plant cytotoxin ricin enters target mammalian cells by receptor-mediated endocytosis and undergoes retrograde transport to the endoplasmic reticulum (ER). Here, its catalytic A chain (RTA) is reductively separated from the cell-binding B chain, and free RTA enters the cytosol where it inactivates ribosomes. Cytosolic entry requires unfolding of RTA and dislocation across the ER membrane such that it arrives in the cytosol in a vulnerable, nonnative conformation. Clearly, for such a dislocated toxin to become active, it must avoid degradation and fold to a catalytic conformation. Here, we show that, in vitro, Hsc70 prevents aggregation of heat-treated RTA, and that RTA catalytic activity is recovered after chaperone treatment. A combination of pharmacological inhibition and cochaperone expression reveals that, in vivo, cytosolic RTA is scrutinized sequentially by the Hsc70 and Hsp90 cytosolic chaperone machineries, and that its eventual fate is determined by the balance of activities of cochaperones that regulate Hsc70 and Hsp90 functions. Cytotoxic activity follows Hsc70-mediated escape of RTA from an otherwise destructive pathway facilitated by Hsp90. We demonstrate a role for cytosolic chaperones, proteins typically associated with folding nascent proteins, assembling multimolecular protein complexes and degrading cytosolic and stalled, cotranslocational clients, in a toxin triage, in which both toxin folding and degradation are initiated from chaperone-bound states
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