372 research outputs found
Measurements of the Solid-body Rotation of Anisotropic Particles in 3D Turbulence
We introduce a new method to measure Lagrangian vorticity and the rotational
dynamics of anisotropic particles in a turbulent fluid flow. We use 3D printing
technology to fabricate crosses (two perpendicular rods) and jacks (three
mutually perpendicular rods). Time-resolved measurements of their orientation
and solid-body rotation rate are obtained from stereoscopic video images of
their motion in a turbulent flow between oscillating grids with
=. The advected particles have a largest dimension of 6 times
the Kolmogorov length, making them a good approximation to anisotropic tracer
particles. Crosses rotate like disks and jacks rotate like spheres, so these
measurements, combined with previous measurements of tracer rods, allow
experimental study of ellipsoids across the full range of aspect ratios. The
measured mean square tumbling rate, ,
confirms previous direct numerical simulations that indicate that disks tumble
much more rapidly than rods. Measurements of the alignment of crosses with the
direction of the solid-body rotation rate vector provide the first direct
observation of the alignment of anisotropic particles by the velocity gradients
of the flow.Comment: 15 pages, 7 figure
Multi-Q mesoscale magnetism in CeAuSb
We report the discovery of a field driven transition from a striped to woven
Spin Density Wave (SDW) in the tetragonal heavy fermion compound CeAuSb.
Polarized along , the sinusoidal SDW amplitude is 1.8(2) /Ce for
=6.25(10) K with wavevector (). For , harmonics appearing at
evidence a striped magnetic texture below T. Above , these are replaced by woven harmonics at
until T, where satellites vanish and magnetization non-linearly
approaches saturation at 1.64(2) /Ce for T.Comment: 5 pages, 4 figure
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Confirmation of Genetic Associations at ELMO1 in the GoKinD Collection Supports Its Role as a Susceptibility Gene in Diabetic Nephropathy
Objective: To examine the association between single nucleotide polymorphisms (SNPs) in the engulfment and cell motility 1 (ELMO1) gene, a locus previously shown to be associated with diabetic nephropathy in two ethnically distinct type 2 diabetic populations, and the risk of nephropathy in type 1 diabetes. Research Design and Methods: Genotypic data from a genome-wide association scan (GWAS) of the Genetics of Kidneys in Diabetes (GoKinD) study collection were analyzed for associations across the ELMO1 locus. In total, genetic associations were assessed using 118 SNPs and 1,705 individuals of European ancestry with type 1 diabetes (885 normoalbuminuric control subjects and 820 advanced diabetic nephropathy case subjects). Results: The strongest associations in ELMO1 occurred at rs11769038 (odds ratio [OR] 1.24; P = 1.7 × 10−3) and rs1882080 (OR 1.23; P = 3.2 × 10−3) located in intron 16. Two additional SNPs, located in introns 18 and 20, respectively, were also associated with diabetic nephropathy. No evidence of association for variants previously reported in type 2 diabetes was observed in our collection. Conclusions: Using GWAS data from the GoKinD collection, we comprehensively examined evidence of association across the ELMO1 locus. Our investigation marks the third report of associations in ELMO1 with diabetic nephropathy, further establishing its role in the susceptibility of this disease. There is evidence of allelic heterogeneity, contributed by the diverse genetic backgrounds of the different ethnic groups examined. Further investigation of SNPs at this locus is necessary to fully understand the commonality of these associations and the mechanism(s) underlying their role in diabetic nephropathy
Epidemiology, patterns of care, and mortality for patients with acute respiratory distress syndrome in intensive care units in 50 countries
IMPORTANCE: Limited information exists about the epidemiology, recognition, management, and outcomes of patients with the acute respiratory distress syndrome (ARDS).
OBJECTIVES: To evaluate intensive care unit (ICU) incidence and outcome of ARDS and to assess clinician recognition, ventilation management, and use of adjuncts-for example prone positioning-in routine clinical practice for patients fulfilling the ARDS Berlin Definition.
DESIGN, SETTING, AND PARTICIPANTS:The Large Observational Study to Understand the Global Impact of Severe Acute Respiratory Failure (LUNG SAFE) was an international, multicenter, prospective cohort study of patients undergoing invasive or noninvasive ventilation, conducted during 4 consecutive weeks in the winter of 2014 in a convenience sample of 459 ICUs from 50 countries across 5 continents.
EXPOSURES:Acute respiratory distress syndrome.
MAIN OUTCOMES AND MEASURES: The primary outcome was ICU incidence of ARDS. Secondary outcomes included assessment of clinician recognition of ARDS, the application of ventilatory management, the use of adjunctive interventions in routine clinical practice, and clinical outcomes from ARDS.
RESULTS: Of 29,144 patients admitted to participating ICUs, 3022 (10.4%) fulfilled ARDS criteria. Of these, 2377 patients developed ARDS in the first 48 hours and whose respiratory failure was managed with invasive mechanical ventilation. The period prevalence of mild ARDS was 30.0% (95% CI, 28.2%-31.9%); of moderate ARDS, 46.6% (95% CI, 44.5%-48.6%); and of severe ARDS, 23.4% (95% CI, 21.7%-25.2%). ARDS represented 0.42 cases per ICU bed over 4 weeks and represented 10.4% (95% CI, 10.0%-10.7%) of ICU admissions and 23.4% of patients requiring mechanical ventilation. Clinical recognition of ARDS ranged from 51.3% (95% CI, 47.5%-55.0%) in mild to 78.5% (95% CI, 74.8%-81.8%) in severe ARDS. Less than two-thirds of patients with ARDS received a tidal volume 8 of mL/kg or less of predicted body weight. Plateau pressure was measured in 40.1% (95% CI, 38.2-42.1), whereas 82.6% (95% CI, 81.0%-84.1%) received a positive end-expository pressure (PEEP) of less than 12 cm H2O. Prone positioning was used in 16.3% (95% CI, 13.7%-19.2%) of patients with severe ARDS. Clinician recognition of ARDS was associated with higher PEEP, greater use of neuromuscular blockade, and prone positioning. Hospital mortality was 34.9% (95% CI, 31.4%-38.5%) for those with mild, 40.3% (95% CI, 37.4%-43.3%) for those with moderate, and 46.1% (95% CI, 41.9%-50.4%) for those with severe ARDS.
CONCLUSIONS AND RELEVANCE: Among ICUs in 50 countries, the period prevalence of ARDS was 10.4% of ICU admissions. This syndrome appeared to be underrecognized and undertreated and associated with a high mortality rate. These findings indicate the potential for improvement in the management of patients with ARDS
The Sphaleron Rate in SU(N) Gauge Theory
The sphaleron rate is defined as the diffusion constant for topological
number NCS = int g^2 F Fdual/32 pi^2. It establishes the rate of equilibration
of axial light quark number in QCD and is of interest both in electroweak
baryogenesis and possibly in heavy ion collisions. We calculate the
weak-coupling behavior of the SU(3) sphaleron rate, as well as making the most
sensible extrapolation towards intermediate coupling which we can. We also
study the behavior of the sphaleron rate at weak coupling at large Nc.Comment: 18 pages with 3 figure
The history of degenerate (bipartite) extremal graph problems
This paper is a survey on Extremal Graph Theory, primarily focusing on the
case when one of the excluded graphs is bipartite. On one hand we give an
introduction to this field and also describe many important results, methods,
problems, and constructions.Comment: 97 pages, 11 figures, many problems. This is the preliminary version
of our survey presented in Erdos 100. In this version 2 only a citation was
complete
The genomes of two key bumblebee species with primitive eusocial organization
Background: The shift from solitary to social behavior is one of the major evolutionary transitions. Primitively eusocial bumblebees are uniquely placed to illuminate the evolution of highly eusocial insect societies. Bumblebees are also invaluable natural and agricultural pollinators, and there is widespread concern over recent population declines in some species. High-quality genomic data will inform key aspects of bumblebee biology, including susceptibility to implicated population viability threats. Results: We report the high quality draft genome sequences of Bombus terrestris and Bombus impatiens, two ecologically dominant bumblebees and widely utilized study species. Comparing these new genomes to those of the highly eusocial honeybee Apis mellifera and other Hymenoptera, we identify deeply conserved similarities, as well as novelties key to the biology of these organisms. Some honeybee genome features thought to underpin advanced eusociality are also present in bumblebees, indicating an earlier evolution in the bee lineage. Xenobiotic detoxification and immune genes are similarly depauperate in bumblebees and honeybees, and multiple categories of genes linked to social organization, including development and behavior, show high conservation. Key differences identified include a bias in bumblebee chemoreception towards gustation from olfaction, and striking differences in microRNAs, potentially responsible for gene regulation underlying social and other traits. Conclusions: These two bumblebee genomes provide a foundation for post-genomic research on these key pollinators and insect societies. Overall, gene repertoires suggest that the route to advanced eusociality in bees was mediated by many small changes in many genes and processes, and not by notable expansion or depauperation
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Genome-Wide Association Scan for Diabetic Nephropathy Susceptibility Genes in Type 1 Diabetes
OBJECTIVE—Despite extensive evidence for genetic susceptibility
to diabetic nephropathy, the identification of susceptibility
genes and their variants has had limited success. To search for
genes that contribute to diabetic nephropathy, a genome-wide
association scan was implemented on the Genetics of Kidneys in
Diabetes collection.
RESEARCH DESIGN AND METHODS—We genotyped
360,000 single nucleotide polymorphisms (SNPs) in 820 case
subjects (284 with proteinuria and 536 with end-stage renal
disease) and 885 control subjects with type 1 diabetes. Confirmation
of implicated SNPs was sought in 1,304 participants of the
Diabetes Control and Complications Trial (DCCT)/Epidemiology
of Diabetes Interventions and Complications (EDIC) study, a
long-term, prospective investigation of the development of diabetes-
associated complications.
RESULTS—A total of 13 SNPs located in four genomic loci were
associated with diabetic nephropathy with P1105. The
strongest association was at the FRMD3 (4.1 protein ezrin,
radixin, moesin [FERM] domain containing 3) locus (odds ratio
[OR]1.45, P5.0107). A strong association was also
identified at the CARS (cysteinyl-tRNA synthetase) locus (OR
1.36, P3.1106). Associations between both loci and time to
onset of diabetic nephropathy were supported in the DCCT/EDIC
study (hazard ratio [HR]1.33, P0.02, and HR1.32, P
0.01, respectively). We demonstrated expression of both FRMD3
and CARS in human kidney.
CONCLUSIONS—We identified genetic associations for susceptibility
to diabetic nephropathy at two novel candidate loci near
the FRMD3 and CARS genes. Their identification implicates
previously unsuspected pathways in the pathogenesis of this
important late complication of type 1 diabetes
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