70 research outputs found
Human Leptospirosis Infection in Fiji: An Eco-epidemiological Approach to Identifying Risk Factors and Environmental Drivers for Transmission.
Leptospirosis is an important zoonotic disease in the Pacific Islands. In Fiji, two successive cyclones and severe flooding in 2012 resulted in outbreaks with 576 reported cases and 7% case-fatality. We conducted a cross-sectional seroprevalence study and used an eco-epidemiological approach to characterize risk factors and drivers for human leptospirosis infection in Fiji, and aimed to provide an evidence base for improving the effectiveness of public health mitigation and intervention strategies. Antibodies indicative of previous or recent infection were found in 19.4% of 2152 participants (81 communities on the 3 main islands). Questionnaires and geographic information systems data were used to assess variables related to demographics, individual behaviour, contact with animals, socioeconomics, living conditions, land use, and the natural environment. On multivariable logistic regression analysis, variables associated with the presence of Leptospira antibodies included male gender (OR 1.55), iTaukei ethnicity (OR 3.51), living in villages (OR 1.64), lack of treated water at home (OR 1.52), working outdoors (1.64), living in rural areas (OR 1.43), high poverty rate (OR 1.74), living <100m from a major river (OR 1.41), pigs in the community (OR 1.54), high cattle density in the district (OR 1.04 per head/sqkm), and high maximum rainfall in the wettest month (OR 1.003 per mm). Risk factors and drivers for human leptospirosis infection in Fiji are complex and multifactorial, with environmental factors playing crucial roles. With global climate change, severe weather events and flooding are expected to intensify in the South Pacific. Population growth could also lead to more intensive livestock farming; and urbanization in developing countries is often associated with urban and peri-urban slums where diseases of poverty proliferate. Climate change, flooding, population growth, urbanization, poverty and agricultural intensification are important drivers of zoonotic disease transmission; these factors may independently, or potentially synergistically, lead to enhanced leptospirosis transmission in Fiji and other similar settings
Predictive risk mapping of an environmentally-driven infectious disease using spatial Bayesian networks: A case study of leptospirosis in Fiji
Introduction
Leptospirosis is a zoonotic disease responsible for over 1 million severe cases and 60,000 deaths annually. The wide range of animal hosts and complex environmental drivers of transmission make targeted interventions challenging, particularly when restricted to regression-based analyses which have limited ability to deal with complexity. In Fiji, important environmental and socio-demographic factors include living in rural areas, poverty, and livestock exposure. This study aims to examine drivers of transmission under different scenarios of environmental and livestock exposures.
Methods
Spatial Bayesian networks (SBN) were used to analyse the influence of livestock and poverty on the risk of leptospirosis infection in urban compared to rural areas. The SBN models used a combination of spatially-explicit field data from previous work and publically available census information. Predictive risk maps were produced for overall risk, and for scenarios related to poverty, livestock, and urban/rural setting.
Results
While high, rather than low, commercial dairy farm density similarly increased the risk of infection in both urban (12% to 18%) and rural areas (70% to 79%), the presence of pigs in a village had different impact in rural (43% to 84%) compared with urban areas (4% to 24%). Areas with high poverty rates were predicted to have 26.6% and 18.0% higher probability of above average seroprevalence in rural and urban areas, respectively. In urban areas, this represents >300% difference between areas of low and high poverty, compared to 43% difference in rural areas.
Conclusions
Our study demonstrates the use of SBN to provide valuable insights into the drivers of leptospirosis transmission under complex scenarios. By estimating the risk of leptospirosis infection under different scenarios, such as urban versus rural areas, these subgroups or areas can be targeted with more precise interventions that focus on the most relevant key drivers of infection
Detection of chemical warfare agent simulants and hydrolysis products in biological samples by paper spray mass spectrometry
Paper spray ionization coupled to a high resolution tandem mass spectrometer (a quadrupole orbitrap) was used to identify and quantitate chemical warfare agent (CWA) simulants and their hydrolysis products in blood and urine. Three CWA simulants, dimethyl methylphosphonate (DMMP), trimethyl phosphate (TMP), and diisopropyl methylphosphonate (DIMP), and their isotopically labeled standards were analyzed in human whole blood and urine. Calibration curves were generated and tested with continuing calibration verification standards. Limits of detection for these three compounds were in the low ng mLâ1 range for the direct analysis of both blood and urine samples. Five CWA hydrolysis products, ethyl methylphosphonic acid (EMPA), isopropyl methylphosphonic acid (IMPA), isobutyl methylphosphonic acid (iBuMPA), cyclohexyl methylphosphonic acid (CHMPA), and pinacolyl methylphosphonic acid (PinMPA), were also analyzed. Calibration curves were generated in both positive and negative ion modes. Limits of detection in the negative ion mode ranged from 0.36 ng mLâ1 to 1.25 ng mLâ1 in both blood and urine for the hydrolysis products. These levels were well below those found in victims of the Tokyo subway attack of 2 to 135 ng mLâ1. Improved stability and robustness of the paper spray technique in the negative ion mode was achieved by the addition of chlorinated solvents. These applications demonstrate that paper spray mass spectrometry (PS-MS) can be used for rapid, sample preparation-free detection of chemical warfare agents and their hydrolysis products at physiologically relevant concentrations in biological samples
Transmission of Supersymmetry Breaking from a 4-Dimensional Boundary
In the strong-coupling limit of the heterotic string theory constructed by
Horava and Witten, an 11-dimensional supergravity theory is coupled to matter
multiplets confined to 10-dimensional mirror planes. This structure suggests
that realistic unification models are obtained, after compactification of 6
dimensions, as theories of 5-dimensional supergravity in an interval, coupling
to matter fields on 4-dimensional walls. Supersymmetry breaking may be
communicated from one boundary to another by the 5-dimensional fields. In this
paper, we study a toy model of this communication in which 5-dimensional
super-Yang-Mills theory in the bulk couples to chiral multiplets on the walls.
Using the auxiliary fields of the Yang-Mills multiplet, we find a simple
algorithm for coupling the bulk and boundary fields. We demonstrate two
different mechanisms for generating soft supersymmetry breaking terms in the
boundary theory. We also compute the Casimir energy generated by supersymmetry
breaking.Comment: 26 pages, latex + 7 eps figures, final correction
Direct Analysis of Aerosolized Chemical Warfare Simulants Captured on a Modified Glass-Based Substrate by âPaper-Sprayâ Ionization
Paper spray ionization mass spectrometry offers a rapid alternative platform requiring no sample preparation. Aerosolized chemical warfare agent (CWA) simulants trimethyl phosphate, dimethyl methylphosphonate, and diisopropyl methylphosphonate were captured by passing air through a glass fiber filter disk within a disposable paper spray cartridge. CWA simulants were aerosolized at varying concentrations using an in-house built aerosol chamber. A custom 3D-printed holder was designed and built to facilitate the aerosol capture onto the paper spray cartridges. The air flow through each of the collection devices was maintained equally to ensure the same volume of air sampled across methods. Each approach yielded linear calibration curves with R2 values between 0.98â0.99 for each compound and similar limits of detection in terms of disbursed aerosol concentration. While the glass fiber filter disk has a higher capture efficiency (â40%), the paper spray method produces analogous results even with a lower capture efficiency (â1%). Improvements were made to include glass fiber filters as the substrate within the paper spray cartridge consumable. Glass fiber filters were then treated with ammonium sulfate to decrease chemical interaction with the simulants. This allowed for improved direct aerosol capture efficiency (>40%). Ultimately, the limits of detection were reduced to levels comparable to current worker population limits of 1 Ă 10â6 mg/m3
Two-Loop Renormalization Group Equations for Soft Supersymmetry-Breaking Couplings
We compute the two-loop renormalization group equations for all soft
supersymmetry-breaking couplings in a general softly broken N=1 supersymmetric
model. We also specialize these results to the Minimal Supersymmetric Standard
Model.Comment: 26 pages. [v4: Signs of equations (4.2) and (4.3) are fixed.
Flavor Symmetries and The Problem of Squark Degeneracy
If supersymmetry exists at low energies, it is necessary to understand why
the squark spectrum exhibits sufficient degeneracy to suppress flavor changing
neutral currents. In this note, we point out that gauged horizontal symmetries
can yield realistic quark mass matrices, while at the same time giving just
barely enough squark degeneracy to account for neutral -meson phenomenology.
This approach suggests likely patterns for squark masses, and indicates that
there could be significant supersymmetric contributions to and
mixing and CP violation in the and systems.Comment: preprint SCIPP 93/04,SLAC-PUB-6147, 14 pages, 4 tables included; uses
macro package TABLES.TEX and phyzzx forma
Metastable Vacua in Flux Compactifications and Their Phenomenology
In the context of flux compactifications, metastable vacua with a small
positive cosmological constant are obtained by combining a sector where
supersymmetry is broken dynamically with the sector responsible for moduli
stabilization, which is known as the F-uplifting. We analyze this procedure in
a model-independent way and study phenomenological properties of the resulting
vacua.Comment: 21 pages, 19 figures; v2: matches version published in JHE
Gaugino production in proton-proton collisions at a center-of-mass energy of 8 TeV
Motivated by hints for a light Standard Model-like Higgs boson and a shift in
experimental attention towards electroweak supersymmetry particle production at
the CERN LHC, we update in this paper our precision predictions at
next-to-leading order of perturbative QCD matched to resummation at the
next-to-leading logarithmic accuracy for direct gaugino pair production in
proton-proton collisions with a center-of-mass energy of 8 TeV. Tables of total
cross sections are presented together with the corresponding scale and parton
density uncertainties for benchmark points adopted recently by the experimental
collaborations, and figures are presented for up-to-date model lines attached
to them. Since the experimental analyses are currently obtained with parton
showers matched to multi-parton matrix elements, we also analyze the precision
of this procedure by comparing invariant-mass and transverse-momentum
distributions obtained in this way to those obtained with threshold and
transverse-momentum resummation.Comment: 28 pages, 7 figures, 9 tables; version to appear in JHE
Supersymmetric top and bottom squark production at hadron colliders
The scalar partners of top and bottom quarks are expected to be the lightest
squarks in supersymmetric theories, with potentially large cross sections at
hadron colliders. We present predictions for the production of top and bottom
squarks at the Tevatron and the LHC, including next-to-leading order
corrections in supersymmetric QCD and the resummation of soft gluon emission at
next-to-leading-logarithmic accuracy. We discuss the impact of the higher-order
corrections on total cross sections and transverse-momentum distributions, and
provide an estimate of the theoretical uncertainty due to scale variation and
the parton distribution functions.Comment: 29 pages, 6 figure
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