1,616 research outputs found
Should New Anti-Malarial Drugs be Subsidized?
We use analytical and numerical models to explain and quantify the welfare effects of subsidies for artemisinin combination treatments (ACTs), a valuable new class of antimalarial drugs. There are two (second-best) efficiency rationales for such subsidies: by expanding drug use, they reduce infection transmission from one individual to another, and they slow the evolution of drug resistance by deterring use of substitute monotherapy drugs for which resistance emerges more rapidly than for ACTs. Our analysis merges epidemiological models of malaria transmission among individuals and mosquitoes, evolution of drug resistance, and economic models of the demand for alternative drugs; parameter values for the simulations are representative of malaria prevalence in sub-Saharan Africa. We find that large subsidies for ACT are welfare improving across many plausible scenarios for malaria transmission, drug-demand elasticities, and evolution of drug resistance; the benefits of the policy are often several times larger than the costs.antimalarial drugs, resistance externality, transmission externality, subsidies, welfare effects
Intestinal Microbiota-Dependent Phosphatidylcholine Metabolites, Diastolic Dysfunction, and Adverse Clinical Outcomes in Chronic Systolic Heart Failure
Background: Trimethylamine-N-oxide (TMAO) has been linked to increased cardiovascular risk. We aimed to determine the prognostic value of TMAO and its dietary precursors, choline and betaine, in heart failure (HF). Methods and Results: In 112 patients with chronic systolic HF with comprehensive echocardiographic evaluation, we measured plasma TMAO, choline, and betaine by mass spectrometry. Median (interquartile range) TMAO levels, choline, and betaine levels were 5.8 (3.6–12.1) μmol/L, 10.9 (8.4–14.0) μmol/L, and 43.8 (37.1–53.0) μmol/L, respectively, and were correlated with each other (all P \u3c .0001 for both). TMAO levels were significantly higher in patients with diabetes mellitus (9.4 [4.9–13.2] vs 4.8 [3.4–9.8] μmol/L; P = .005) and in subjects with New York Heart Association functional class III or greater (7.0 [4.7–14.8] vs 4.7 [3.4–11.3] μmol/L; P = .02). Elevated TMAO, choline, and betaine levels were each associated with higher plasma N-terminal pro–B-type natriuretic peptide (NT-proBNP) levels and more advanced left ventricular diastolic dysfunction, but not systolic dysfunction or inflammatory and endothelial biomarkers. Higher choline (hazard ratio [HR] 1.64, 95% CI 1.22–2.20; P = .001), betaine (HR 1.51, 95% CI 1.10–2.08; P = .01), and TMAO (HR 1.48, 95% CI 1.10–1.96; P = .01) predicted increased risk for 5-year adverse clinical events (death/transplantation). Only higher TMAO levels predicted incident adverse clinical events independently from age, estimated glomerular filtration rate, mitral E/septal Ea, and NT-proBNP levels (HR 1.46, 95% CI 1.03–2.14; P = .03). Conclusion: Elevated plasma TMAO, choline, and betaine levels are each associated with more advanced left ventricular diastolic dysfunction and portend poorer long-term adverse clinical outcomes in chronic systolic HF. However, only higher plasma TMAO was associated with poor prognosis after adjustment for cardiorenal indices
Success or failure in knowledge management systems: a universal issue
This paper takes a sociotechnical viewpoint of knowledge management system (KMS) implementation in organizations considering issues such as stakeholder disenfranchisement, lack of communication, and the low involvement of key personnel in system design asking whether KMS designers could learn from applying sociotechnical principles to their systems. The paper discusses design elements drawn from the sociotechnical principles essential for the success of IS and makes recommendations to increase the success of KMS
in organizations. It also provides guidelines derived from Clegg’s Principles (2000) for KMS designers to enhance their designs. Our data comes from the
application of a plurality of analysis methods on a large comprehensive global survey conducted from 2007 to 2011 of 1034 participants from 76 countries.
The survey covers a variety of organizations of all types and sizes from a comprehensive selection of economic sectors and industries. Our results showed
that users were not satisfied with the information and knowledge systems that they were being offered. In addition to multiple technology and usability issues,
there were human and organisational barriers that prevented the systems from being used to their full potential. We recommend that users of KMS are integrated
into the design team so that these usability and other barriers can be addressed during the feasibility stage as well as the actual design and implementation
phases
Violation of the Mott-Ioffe-Regel Limit: High-temperature Resistivity of Itinerant Magnets Srn+1RunO3n+1 (n=2,3,infinity) and CaRuO3
Srn+1RunO3n+1 represents a class of layered materials whose physical
properties are a strong function of the number of Ru-O layers per unit cell, n.
This series includes the p-wave superconductor Sr2RuO4 (n=1), enhanced
paramagnetic Sr3Ru2O7 (n=2), nearly ferromagnetic Sr4Ru3O10 (n=3) and itinerant
ferromagnetic SrRuO3 (n=infinity). In spite of a wide spectrum of physical
phenomena, this series of materials along with paramagnetic CaRuO3 shares two
major characteristics, namely, robust Fermi liquid behavior at low temperatures
and anomalous transport behavior featured by linear temperature dependence of
resistivity at high temperature where electron wavepackets are no longer
clearly defined. There is no crossover separating such two fundamentally
different states. In this paper, we report results of our study that
systematically addresses anisotropy and temperature dependence of basal-plane
and c-axis resistivity as a function of n for the entire Srn+1RunO3n+1 series
and CaRuO3 and for a wide temperature range of 1.7 K<T<900 K. It is found that
the anomalous transport behavior correlates with magnetic susceptibility and
becomes stronger with decreasing dimensionality. Implications of these results
are discussed
Widening and distortion of the particle energy distributionby chromaticity in quasi isochronous rings
Origins of the Ambient Solar Wind: Implications for Space Weather
The Sun's outer atmosphere is heated to temperatures of millions of degrees,
and solar plasma flows out into interplanetary space at supersonic speeds. This
paper reviews our current understanding of these interrelated problems: coronal
heating and the acceleration of the ambient solar wind. We also discuss where
the community stands in its ability to forecast how variations in the solar
wind (i.e., fast and slow wind streams) impact the Earth. Although the last few
decades have seen significant progress in observations and modeling, we still
do not have a complete understanding of the relevant physical processes, nor do
we have a quantitatively precise census of which coronal structures contribute
to specific types of solar wind. Fast streams are known to be connected to the
central regions of large coronal holes. Slow streams, however, appear to come
from a wide range of sources, including streamers, pseudostreamers, coronal
loops, active regions, and coronal hole boundaries. Complicating our
understanding even more is the fact that processes such as turbulence,
stream-stream interactions, and Coulomb collisions can make it difficult to
unambiguously map a parcel measured at 1 AU back down to its coronal source. We
also review recent progress -- in theoretical modeling, observational data
analysis, and forecasting techniques that sit at the interface between data and
theory -- that gives us hope that the above problems are indeed solvable.Comment: Accepted for publication in Space Science Reviews. Special issue
connected with a 2016 ISSI workshop on "The Scientific Foundations of Space
Weather." 44 pages, 9 figure
Measurement of (anti)deuteron and (anti)proton production in DIS at HERA
The first observation of (anti)deuterons in deep inelastic scattering at HERA
has been made with the ZEUS detector at a centre-of-mass energy of 300--318 GeV
using an integrated luminosity of 120 pb-1. The measurement was performed in
the central rapidity region for transverse momentum per unit of mass in the
range 0.3<p_T/M<0.7. The particle rates have been extracted and interpreted in
terms of the coalescence model. The (anti)deuteron production yield is smaller
than the (anti)proton yield by approximately three orders of magnitude,
consistent with the world measurements.Comment: 26 pages, 9 figures, 5 tables, submitted to Nucl. Phys.
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