3,119 research outputs found
Mind the gap! A multilevel analysis of factors related to variation in published cost-effectiveness estimates within and between countries
Background. Published cost-effectiveness estimates can vary considerably, both within and between countries. Despite extensive discussion, little is known empirically about factors relating to these variations. Objectives. To use multilevel statistical modeling to integrate cost-effectiveness estimates from published economic evaluations to investigate potential causes of variation. Methods. Cost-effectiveness studies of statins for cardiovascular disease prevention were identified by systematic review. Estimates of incremental costs and effects were extracted from reported base case, sensitivity, and subgroup analyses, with estimates grouped in studies and in countries. Three bivariate models were developed: a cross-classified model to accommodate data from multinational studies, a hierarchical model with multinational data allocated to a single category at country level, and a hierarchical model excluding multinational data. Covariates at different levels were drawn from a long list of factors suggested in the literature. Results. We found 67 studies reporting 2094 cost-effectiveness estimates relating to 23 countries (6 studies reporting for more than 1 country). Data and study-level covariates included patient characteristics, intervention and comparator cost, and some study methods (e.g., discount rates and time horizon). After adjusting for these factors, the proportion of variation attributable to countries was negligible in the cross-classified model but moderate in the hierarchical models (14%−19% of total variance). Country-level variables that improved the fit of the hierarchical models included measures of income and health care finance, health care resources, and population risks. Conclusions. Our analysis suggested that variability in published cost-effectiveness estimates is related more to differences in study methods than to differences in national context. Multinational studies were associated with much lower country-level variation than single-country studies. These findings are for a single clinical question and may be atypical
Valaciclovir for Chronic Hepatitis BVirus Infection after Lung Transplantation
Abstract. : We report on a chronic asymptomatic hepatitis B surface antigen (HBsAg) carrier who developed an increase in aminotransferase and HBsAg levels 1 year after lung transplantation. During treatment for cutaneous herpes simplex virus (HSV) infection with oral valaciclovir there was a marked decrease in replicating hepatitis B virus (HBV)-DNA and aminotransferase levels, which was sustained for 9 months by continuing low-dose valaciclovir. A second rise in aminotransferase levels again responded to a valaciclovir dose increase and the HBV-DNA levels declined further. Although we cannot exclude a spontaneous variation of the serologic parameters, our observation suggests that valaciclovir may represent a valuable therapeutic option in the treatment of chronic hepatitis B after lung transplantatio
The complex morphology of the young disk MWC 758: Spirals and dust clumps around a large cavity
We present Atacama Large Millimeter Array (ALMA) observations at an angular
resolution of 0.1-0.2" of the disk surrounding the young Herbig Ae star MWC
758. The data consist of images of the dust continuum emission recorded at 0.88
millimeter, as well as images of the 13CO and C18O J = 3-2 emission lines. The
dust continuum emission is characterized by a large cavity of roughly 40 au in
radius which might contain a mildly inner warped disk. The outer disk features
two bright emission clumps at radii of about 47 and 82 au that present
azimuthal extensions and form a double-ring structure. The comparison with
radiative transfer models indicates that these two maxima of emission
correspond to local increases in the dust surface density of about a factor 2.5
and 6.5 for the south and north clumps, respectively. The optically thick 13CO
peak emission, which traces the temperature, and the dust continuum emission,
which probes the disk midplane, additionally reveal two spirals previously
detected in near-IR at the disk surface. The spirals seen in the dust continuum
emission present, however, a slight shift of a few au towards larger radii and
one of the spirals crosses the south dust clump. Finally, we present different
scenarios in order to explain the complex structure of the disk.Comment: 15 pages, 11 figures. The paper has been published in ApJ. References
added and typos correcte
Melting of tantalum at high pressure determined by angle dispersive x-ray diffraction in a double-sided laser-heated diamond-anvil cell
The high pressure and high temperature phase diagram of Ta has been studied
in a laser-heated diamond-anvil cell (DAC) using x-ray diffraction measurements
up to 52 GPa and 3800 K. The melting was observed at nine different pressures,
being the melting temperature in good agreement with previous laser-heated DAC
experiments, but in contradiction with several theoretical calculations and
previous piston-cylinder apparatus experiments. A small slope for the melting
curve of Ta is estimated (dTm/dP = 24 K/GPa at 1 bar) and a possible
explanation for this behaviour is given. Finally, a P-V-T equation of states is
obtained, being the temperature dependence of the thermal expansion coefficient
and the bulk modulus estimated.Comment: 31 pages, 8 figures, to appear in J.Phys.:Cond.Matte
Evaluation of Information Systems Curricula
Information systems education objectives must continually adapt to a dynamic marketplace for knowledge and skills. For faculty developing programs that better prepare students for this demanding environment, existing research and guidelines provide a foundation to develop relevant coursework. However, an examination of peer institutions indicates a significant variance in how institutions of higher learning address the requirements of local markets as they prepare their students for careers. This study reviews previous information systems curricula research, examines current guidelines for information systems education, analyzes adherence to those guidelines, and summarizes innovative approaches being used by business colleges in the U.S. to prepare students. Our findings indicate that even as the number of information systems programs decline, colleges are looking for relevant ways to serve their students and communities. For information systems education to remain connected to the marketplace, the value provided by a degree in information systems must be clear to future employers. This paper concludes by offering insights gained by an analysis of thriving programs to assist faculty working on improving their undergraduate information systems curriculum
Dynamical Masses of Low Mass Stars in the Taurus and Ophiuchus Star Forming Regions
We report new dynamical masses for 5 pre-main sequence (PMS) stars in the
L1495 region of the Taurus star-forming region (SFR) and 6 in the L1688 region
of the Ophiuchus SFR. Since these regions have VLBA parallaxes these are
absolute measurements of the stars' masses and are independent of their
effective temperatures and luminosities. Seven of the stars have masses
solar masses, thus providing data in a mass range with little data, and of
these, 6 are measured to precision . We find 8 stars with masses in the
range 0.09 to 1.1 solar mass that agree well with the current generation of PMS
evolutionary models. The ages of the stars we measured in the Taurus SFR are in
the range 1-3 MY, and MY for those in L1688. We also measured the
dynamical masses of 14 stars in the ALMA archival data for Akeson~\&~Jensen's
Cycle 0 project on binaries in the Taurus SFR. We find that the masses of 7 of
the targets are so large that they cannot be reconciled with reported values of
their luminosity and effective temperature. We suggest that these targets are
themselves binaries or triples.Comment: 20 page
Heterozygosity: An Inconspicuous Meiosis-Linked Intrinsic Mutagen in Mice
The impact of heterozygosity as an intrinsic mutagen in mammals is unknown. In plant models, existent heterozygosity increases the local de novo meiotic mutation rate. Mice offer study of this phenomenon given well-established genomic technologies and strains with known, diverse genomic landscapes of heterozygosity. High resolution genotyping arrays assay heterozygous single-nucleotide polymorphic (SNP) loci and copy number variants (CNVs). Using a J statistic for spatial analysis, 60.9% of autosomes from 707 publicly available array samples have nonrandom spatial associations between heterozygous SNP loci and CNVs. By crossing C57BL/6J inbred mice to DBA/2J inbred mice, heterozygous SNP loci and de novo CNVs were analyzed. Of 43 de novo CNVs in F2 mice compared to both F1 and F2 heterozygous SNP landscapes, 33 and 7 were found to co-localize with heterozygous SNP loci, respectively. Heterozygosity may be an overlooked meiosis-linked contributor to CNV mutagenesis, affecting models of disease risk prediction and evolution
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