1,189 research outputs found
A Simple Algebraic Derivation of the Covariant Anomaly and Schwinger Term
An expression for the curvature of the "covariant" determinant line bundle is
given in even dimensional space-time. The usefulness is guaranteed by its
prediction of the covariant anomaly and Schwinger term. It allows a parallel
derivation of the consistent anomaly and Schwinger term, and their covariant
counterparts, which clarifies the similarities and differences between them. In
particular, it becomes clear that in contrary to the case for anomalies, the
difference between the consistent and covariant Schwinger term can not be
extended to a local form on the space of gauge potentials.Comment: 16 page
TWINLATIN: Twinning European and Latin-American river basins for research enabling sustainable water resources management. Combined Report D3.1 Hydrological modelling report and D3.2 Evaluation report
Water use has almost tripled over the past 50 years and in some regions the water demand already
exceeds supply (Vorosmarty et al., 2000). The world is facing a âglobal water crisisâ; in many
countries, current levels of water use are unsustainable, with systems vulnerable to collapse from even
small changes in water availability. The need for a scientifically-based assessment of the potential
impacts on water resources of future changes, as a basis for society to adapt to such changes, is strong
for most parts of the world. Although the focus of such assessments has tended to be climate change,
socio-economic changes can have as significant an impact on water availability across the four main
use sectors i.e. domestic, agricultural, industrial (including energy) and environmental. Withdrawal
and consumption of water is expected to continue to grow substantially over the next 20-50 years
(Cosgrove & Rijsberman, 2002), and consequent changes in availability may drastically affect society
and economies.
One of the most needed improvements in Latin American river basin management is a higher level of
detail in hydrological modelling and erosion risk assessment, as a basis for identification and analysis
of mitigation actions, as well as for analysis of global change scenarios. Flow measurements are too
costly to be realised at more than a few locations, which means that modelled data are required for the
rest of the basin. Hence, TWINLATIN Work Package 3 âHydrological modelling and extremesâ was
formulated to provide methods and tools to be used by other WPs, in particular WP6 on âPollution
pressure and impact analysisâ and WP8 on âChange effects and vulnerability assessmentâ. With an
emphasis on high and low flows and their impacts, WP3 was originally called âHydrological
modelling, flooding, erosion, water scarcity and water abstractionâ. However, at the TWINLATIN
kick-off meeting it was agreed that some of these issues resided more appropriately in WP6 and WP8,
and so WP3 was renamed to focus on hydrological modelling and hydrological extremes.
The specific objectives of WP3 as set out in the Description of Work are
Tumor growth instability and the onset of invasion
Motivated by experimental observations, we develop a mathematical model of
chemotactically directed tumor growth. We present an analytical study of the
model as well as a numerical one. The mathematical analysis shows that: (i)
tumor cell proliferation by itself cannot generate the invasive branching
behaviour observed experimentally, (ii) heterotype chemotaxis provides an
instability mechanism that leads to the onset of tumor invasion and (iii)
homotype chemotaxis does not provide such an instability mechanism but enhances
the mean speed of the tumor surface. The numerical results not only support the
assumptions needed to perform the mathematical analysis but they also provide
evidence of (i), (ii) and (iii). Finally, both the analytical study and the
numerical work agree with the experimental phenomena.Comment: 12 pages, 8 figures, revtex
Recommended from our members
Developing a scalable training model in global mental health: pilot study of a video-assisted training Program for Generalist Clinicians in Rural Nepal.
BackgroundIn low- and middle-income countries, mental health training often includes sending few generalist clinicians to specialist-led programs for several weeks. Our objective is to develop and test a video-assisted training model addressing the shortcomings of traditional programs that affect scalability: failing to train all clinicians, disrupting clinical services, and depending on specialists.MethodsWe implemented the program -video lectures and on-site skills training- for all clinicians at a rural Nepali hospital. We used Wilcoxon signed-rank tests to evaluate pre- and post-test change in knowledge (diagnostic criteria, differential diagnosis, and appropriate treatment). We used a series of 'Yes' or 'No' questions to assess attitudes about mental illness, and utilized exact McNemar's test to analyze the proportions of participants who held a specific belief before and after the training. We assessed acceptability and feasibility through key informant interviews and structured feedback.ResultsFor each topic except depression, there was a statistically significant increase (Î) in median scores on knowledge questionnaires: Acute Stress Reaction (Î = 20, p = 0.03), Depression (Î = 11, p = 0.12), Grief (Î = 40, p < 0.01), Psychosis (Î = 22, p = 0.01), and post-traumatic stress disorder (Î = 20, p = 0.01). The training received high ratings; key informants shared examples and views about the training's positive impact and complementary nature of the program's components.ConclusionVideo lectures and on-site skills training can address the limitations of a conventional training model while being acceptable, feasible, and impactful toward improving knowledge and attitudes of the participants
Courant-like brackets and loop spaces
We study the algebra of local functionals equipped with a Poisson bracket. We
discuss the underlying algebraic structures related to a version of the
Courant-Dorfman algebra. As a main illustration, we consider the functionals
over the cotangent bundle of the superloop space over a smooth manifold. We
present a number of examples of the Courant-like brackets arising from this
analysis.Comment: 20 pages, the version published in JHE
Large N limit of SO(N) gauge theory of fermions and bosons
In this paper we study the large N_c limit of SO(N_c) gauge theory coupled to
a Majorana field and a real scalar field in 1+1 dimensions extending ideas of
Rajeev. We show that the phase space of the resulting classical theory of
bilinears, which are the mesonic operators of this theory, is OSp_1(H|H
)/U(H_+|H_+), where H|H refers to the underlying complex graded space of
combined one-particle states of fermions and bosons and H_+|H_+ corresponds to
the positive frequency subspace. In the begining to simplify our presentation
we discuss in detail the case with Majorana fermions only (the purely bosonic
case is treated in our earlier work). In the Majorana fermion case the phase
space is given by O_1(H)/U(H_+), where H refers to the complex one-particle
states and H_+ to its positive frequency subspace. The meson spectrum in the
linear approximation again obeys a variant of the 't Hooft equation. The linear
approximation to the boson/fermion coupled case brings an additonal bound state
equation for mesons, which consists of one fermion and one boson, again of the
same form as the well-known 't Hooft equation.Comment: 27 pages, no figure
Chiral de Rham complex on Riemannian manifolds and special holonomy
Interpreting the chiral de Rham complex (CDR) as a formal Hamiltonian
quantization of the supersymmetric non-linear sigma model, we suggest a setup
for the study of CDR on manifolds with special holonomy. We show how to
systematically construct global sections of CDR from differential forms, and
investigate the algebra of the sections corresponding to the covariantly
constant forms associated with the special holonomy. As a concrete example, we
construct two commuting copies of the Odake algebra (an extension of the N=2
superconformal algebra) on the space of global sections of CDR of a Calabi-Yau
threefold and conjecture similar results for G_2 manifolds. We also discuss
quasi-classical limits of these algebras.Comment: 49 pages, title changed, major rewrite with no changes in the main
theorems, published versio
Longitudinal membrane function in functionally anuric patients treated with APD: Data from EAPOS on the effects of glucose and icodextrin prescription
Longitudinal membrane function in functionally anuric patients
treated with APD: Data from EAPOS on the effects of glucose
and icodextrin prescription.
Background: Peritoneal dialysis is associated with changes
in membrane function that can lead eventually to ultrafiltration
(UF) failure. Factors driving these changes are thought to
include hypertonic glucose exposure, but previously reported
associations are confounded by the presence of residual renal
function.
Methods: Longitudinal membrane function (solute transport
and UF capacity) were measured annually in a prospective
cohort of 177 functionally anuric patients as part of the
European Automated Peritoneal Dialysis Outcomes Study
(EAPOS). Subgroup analysis was performed according to glucose
exposure and icodextrin use at baseline.
Results: The whole cohort experienced an increase in solute
transport and reduction in UF capacity at 12 and 24 months
that could not be explained by informative censoring. These
changes were accelerated and more severe in patients using
either 2.27% or 3.86% glucose, or those not using icodextrin
at baseline. These differences could not be explained by age,
comorbidity score, previous time spent on renal replacement,
differential dropout from the study, peritonitis rates, or, by definition,
residual renal function. Patients using icodextrin at baseline
had worse membrane function and were more likely to be
diabetic. There was an association between membrane function
changes and achieved 24-hour ultrafiltration over the 2-year
study period.
Conclusion: Anuric automated peritoneal dialysis (APD) patients
experience significant detrimental changes in membrane
function over a relatively short time period. Glucose appears
to enhance these changes independent of residual renal function. Icodextrin use in these circumstances is associated with
less deterioration in membrane functio
High rates of adherence and treatment success in a public and public-private HIV clinic in India: potential benefits of standardized national care delivery systems
<p>Abstract</p> <p>Background</p> <p>The massive scale-up of antiretroviral treatment (ART) access worldwide has brought tremendous benefit to populations affected by HIV/AIDS. Optimising HIV care in countries with diverse medical systems is critical; however data on best practices for HIV healthcare delivery in resource-constrained settings are limited. This study aimed to understand patient characteristics and treatment outcomes from different HIV healthcare settings in Bangalore, India.</p> <p>Methods</p> <p>Participants from public, private and public-private HIV healthcare settings were recruited between 2007 and 2009 and were administered structured interviews by trained staff. Self-reported adherence was measured using the visual analogue scale to capture adherence over the past month, and a history of treatment interruptions (defined as having missed medications for more than 48 hours in the past three months). In addition, CD4 count and viral load (VL) were measured; genotyping for drug resistance-associated mutations was performed on those who were in virological failure (VL > 1000 copies/ml).</p> <p>Results</p> <p>A total of 471 individuals were included in the analysis (263 from the public facility, 149 from the public-private facility and 59 from the private center). Private facility patients were more likely to be male, with higher education levels and incomes. More participants reported â„ 95% adherence among public and public-private groups compared to private participants (public 97%; private 88%; public-private 93%, p < 0.05). Treatment interruptions were lowest among public participants (1%, 10%, 5% respectively, p < 0.001). Although longer clinic waiting times were experienced by more public participants (48%, compared to private 27%, public-private 19%, p < 0.001), adherence barriers were highest among private (31%) compared with public (10%) and public-private (17%, p < 0.001) participants. Viral load was detectable in 13% public, 22% private and 9% public-private participants (p < 0.05) suggesting fewer treatment failures among public and public-private settings. Drug resistance mutations were found more frequently among private facility patients (20%) compared to those from the public (9%) or public-private facility (8%, p < 0.05).</p> <p>Conclusions</p> <p>Adherence and treatment success was significantly higher among patients from public and public-private settings compared with patients from private facilities. These results suggest a possible benefit of the standardized care delivery system established in public and public-private health facilities where counselling by a multi-disciplinary team of workers is integral to provision of ART. Strengthening and increasing public-private partnerships can enhance the success of national ART programs.</p
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