646 research outputs found
Peripheral blood lymphocyte proliferative responses in cattle infected with or vaccinated against Anaplasma marginale
An assay was developed for measurement of the peripheral blood lymphocyte proliferative response (PBLPR) in cattle infected with or immunised against Anaplasma marginale. PBLPR was not evident in all cattle that had recovered from A. marginale infection. However, A. marginale-sensitised lymphocytes were detected in the spleens of all immune cattle tested in the absence of detectable PBLPR. During the course of initial infection, cattle exhibited detectable PBLPR for a period corresponding with and up to 2 weeks after patent parasitaemia, followed by a second, usually larger peak in PBLPR corresponding to the time of sub-clinical relapse of cattle. Analysis of the PBLPR of A. marginale chronically infected cattle demonstrated highly variable PBLPR between individuals and over time. A positive PBLPR was induced in cattle by vaccination using a crude A. marginale antigen preparation. The PBLPR of vaccinated cattle subsequently infected with A. marginale was markedly different from that of naive cattle, with reduced PBLPR being associated with the onset of parasitaemia. The antigen used in the PBLPR assay was inactivated by proteolysis. Proteolysis also abolished immunity that had been induced in cattle vaccinated using the antigen preparation. A. marginale-sensitised PBL did not proliferate in response to antigen from the heterologous species A. centrale. A. centrale-sensitised PBL, however, responded to A. marginale antigen. Interferon-Îł (IFN-Îł) was detected in PBLPR-assay supernatants and was associated with a strong PBLPR
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Flexible human machine interface for process diagnostics
A flexible human machine interface to design and display graphical and textual process diagnostic information is presented. The system operates on different computer hardware platforms, including PCs under MS Windows and UNIX Workstations under X-Windows, in a client-server architecture. The interface system is customized for specific process applications in a graphical user interface development environment by overlaying the image of the process piping and instrumentation diagram with display objects that are highlighted in color during diagnostic display. Customization of the system is presented for Commonwealth Edison`s Braidwood PWR Chemical and Volume Control System with transients simulated by a full-scale operator-training simulator and diagnosed by a computer-based system
Grain boundary pinning and glassy dynamics in stripe phases
We study numerically and analytically the coarsening of stripe phases in two
spatial dimensions, and show that transient configurations do not achieve long
ranged orientational order but rather evolve into glassy configurations with
very slow dynamics. In the absence of thermal fluctuations, defects such as
grain boundaries become pinned in an effective periodic potential that is
induced by the underlying periodicity of the stripe pattern itself. Pinning
arises without quenched disorder from the non-adiabatic coupling between the
slowly varying envelope of the order parameter around a defect, and its fast
variation over the stripe wavelength. The characteristic size of ordered
domains asymptotes to a finite value $R_g \sim \lambda_0\
\epsilon^{-1/2}\exp(|a|/\sqrt{\epsilon})\epsilon\ll 1\lambda_0a$ a constant of order unity. Random fluctuations allow defect motion to
resume until a new characteristic scale is reached, function of the intensity
of the fluctuations. We finally discuss the relationship between defect pinning
and the coarsening laws obtained in the intermediate time regime.Comment: 17 pages, 8 figures. Corrected version with one new figur
The road to deterministic matrices with the restricted isometry property
The restricted isometry property (RIP) is a well-known matrix condition that
provides state-of-the-art reconstruction guarantees for compressed sensing.
While random matrices are known to satisfy this property with high probability,
deterministic constructions have found less success. In this paper, we consider
various techniques for demonstrating RIP deterministically, some popular and
some novel, and we evaluate their performance. In evaluating some techniques,
we apply random matrix theory and inadvertently find a simple alternative proof
that certain random matrices are RIP. Later, we propose a particular class of
matrices as candidates for being RIP, namely, equiangular tight frames (ETFs).
Using the known correspondence between real ETFs and strongly regular graphs,
we investigate certain combinatorial implications of a real ETF being RIP.
Specifically, we give probabilistic intuition for a new bound on the clique
number of Paley graphs of prime order, and we conjecture that the corresponding
ETFs are RIP in a manner similar to random matrices.Comment: 24 page
Probing Kaluza-Klein Dark Matter with Neutrino Telescopes
In models in which all of the Standard Model fields live in extra universal
dimensions, the lightest Kaluza-Klein (KK) particle can be stable. Calculations
of the one-loop radiative corrections to the masses of the KK modes suggest
that the identity of the lightest KK particle (LKP) is mostly the first KK
excitation of the hypercharge gauge boson. This LKP is a viable dark matter
candidate with an ideal present-day relic abundance if its mass is moderately
large, between 600 to 1200 GeV. Such weakly interacting dark matter particles
are expected to become gravitationally trapped in large bodies, such as the
Sun, and annihilate into neutrinos or other particles that decay into
neutrinos. We calculate the annihilation rate, neutrino flux and the resulting
event rate in present and future neutrino telescopes. The relatively large mass
implies that the neutrino energy spectrum is expected to be well above the
energy threshold of AMANDA and IceCube. We find that the event rate in IceCube
is between a few to tens of events per year.Comment: 13 pages, 3 figures, LaTeX; typos fixed, version to appear in PR
Boundary Liouville theory at c=1
The c=1 Liouville theory has received some attention recently as the
Euclidean version of an exact rolling tachyon background. In an earlier paper
it was shown that the bulk theory can be identified with the interacting c=1
limit of unitary minimal models. Here we extend the analysis of the c=1-limit
to the boundary problem. Most importantly, we show that the FZZT branes of
Liouville theory give rise to a new 1-parameter family of boundary theories at
c=1. These models share many features with the boundary Sine-Gordon theory, in
particular they possess an open string spectrum with band-gaps of finite width.
We propose explicit formulas for the boundary 2-point function and for the
bulk-boundary operator product expansion in the c=1 boundary Liouville model.
As a by-product of our analysis we also provide a nice geometric interpretation
for ZZ branes and their relation with FZZT branes in the c=1 theory.Comment: 37 pages, 1 figure. Minor error corrected, slight change in result
(1.6
Electroweak Symmetry Breaking via UV Insensitive Anomaly Mediation
Anomaly mediation solves the supersymmetric flavor and CP problems. This is
because the superconformal anomaly dictates that supersymmetry breaking is
transmitted through nearly flavor-blind infrared physics that is highly
predictive and UV insensitive. Slepton mass squareds, however, are predicted to
be negative. This can be solved by adding D-terms for U(1)_Y and U(1)_{B-L}
while retaining the UV insensitivity. In this paper we consider electroweak
symmetry breaking via UV insensitive anomaly mediation in several models. For
the MSSM we find a stable vacuum when tanbeta < 1, but in this region the top
Yukawa coupling blows up only slightly above the supersymmetry breaking scale.
For the NMSSM, we find a stable electroweak breaking vacuum but with a chargino
that is too light. Replacing the cubic singlet term in the NMSSM superpotential
with a term linear in the singlet we find a stable vacuum and viable spectrum.
Most of the parameter region with correct vacua requires a large superpotential
coupling, precisely what is expected in the ``Fat Higgs'' model in which the
superpotential is generated dynamically. We have therefore found the first
viable UV complete, UV insensitive supersymmetry breaking model that solves the
flavor and CP problems automatically: the Fat Higgs model with UV insensitive
anomaly mediation. Moreover, the cosmological gravitino problem is naturally
solved, opening up the possibility of realistic thermal leptogenesis.Comment: 27 pages, 3 figures, 1 tabl
Working conditions, psychological distress and suicidal ideation: cross-sectional survey study of UK junior doctors
Background
Evidence attests a link between junior doctorsâ working conditions and psychological distress. Despite increasing concerns around suicidality among junior doctors, little is known about its relationship to their working conditions.
Aims
To (a) establish the prevalence of suicidal ideation among junior doctors in the National Health Service; (b) examine the relationships between perceived working conditions and suicidal ideation; and (c) explore whether psychological distress (e.g. symptoms of depression and anxiety) mediates these relationships.
Method
Junior doctors were recruited between March 2020 and January 2021, for a cross-sectional online survey. We used the Health and Safety Executive's Management Standards Tool; Depression, Anxiety and Stress Scale 21; and Paykel Suicidality Scale to assess working conditions, psychological distress and suicidality, respectively.
Results
Of the 424 participants, 50.2% reported suicidal ideation, including 6.1% who had made an attempt on their own life. Participants who identified as LGBTQ+ (odds ratio 2.18, 95% CI 1.15â4.12) or reported depression symptoms (odds ratio 1.10, 95% CI 1.07â1.14) were more likely to report suicidal ideation. No direct relationships were reported between working conditions (i.e. control, support, role clarity, strained relationships, demand and change) and suicidal ideation. However, depression symptoms mediated all six relationships.
Conclusions
This sample of junior doctors reported alarming levels of suicidal ideation. There may be an indirect relationship between working conditions and suicidal ideation via depressive symptoms. Clearer research exploring the experience of suicidality in junior doctors is needed, including those who identify as LGBTQ+. Systematic interventions addressing working environment are needed to support junior doctorsâ mental health
Importance of the Donor: Fullerene Intermolecular Arrangement for High-Efficiency Organic Photovoltaics
The performance of organic photovoltaic (OPV) material systems are hypothesized to depend strongly on the intermolecular arrangements at the donor:fullerene interfaces. A review of some of the most efficient polymers utilized in polymer:fullerene PV devices, combined with an analysis of reported polymer donor materials wherein the same conjugated backbone was used with varying alkyl substituents, supports this hypothesis. Specifically, the literature shows that higher-performing donorâacceptor type polymers generally have acceptor moieties that are sterically accessible for interactions with the fullerene derivative, whereas the corresponding donor moieties tend to have branched alkyl substituents that sterically hinder interactions with the fullerene. To further explore the idea that the most beneficial polymer:fullerene arrangement involves the fullerene docking with the acceptor moiety, a family of benzo[1,2-b:4,5-bâČ]dithiopheneâthieno[3,4-c]pyrrole-4,6-dione polymers (PBDTTPD derivatives) was synthesized and tested in a variety of PV device types with vastly different aggregation states of the polymer. In agreement with our hypothesis, the PBDTTPD derivative with a more sterically accessible acceptor moiety and a more sterically hindered donor moiety shows the highest performance in bulk-heterojunction, bilayer, and low-polymer concentration PV devices where fullerene derivatives serve as the electron-accepting materials. Furthermore, external quantum efficiency measurements of the charge-transfer state and solid-state two-dimensional (2D) 13C{1H} heteronuclear correlation (HETCOR) NMR analyses support that a specific polymer:fullerene arrangement is present for the highest performing PBDTTPD derivative, in which the fullerene is in closer proximity to the acceptor moiety of the polymer. This work demonstrates that the polymer:fullerene arrangement and resulting intermolecular interactions may be key factors in determining the performance of OPV material systems
Geographies of responsibility
Issues of space, place and politics run deep. There is a long history of the entanglement of the conceptualisation of space and place with the framing of political positions. The injunction to think space relationally is a very general one and, as this collection indicates, can lead in many directions. The particular avenue to be explored in this paper concerns the relationship between identity and responsibility, and the potential georaphies of both
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