2,021 research outputs found
Center for Modeling of Turbulence and Transition (CMOTT). Research briefs: 1990
Brief progress reports of the Center for Modeling of Turbulence and Transition (CMOTT) research staff from May 1990 to May 1991 are given. The objectives of the CMOTT are to develop, validate, and implement the models for turbulence and boundary layer transition in the practical engineering flows. The flows of interest are three dimensional, incompressible, and compressible flows with chemistry. The schemes being studied include the two-equation and algebraic Reynolds stress models, the full Reynolds stress (or second moment closure) models, the probability density function models, the Renormalization Group Theory (RNG) and Interaction Approximation (DIA), the Large Eddy Simulation (LES) and Direct Numerical Simulation (DNS)
Simulation of Asynchronous Instruction Pipelines
This paper presents the ARAS simulator with which asynchronous instruction pipelines can be modelled, simulated and displayed. ARAS allows one to construct instruction pipelines by preparing various configuration files. Using these files and a number of benchmark programs, performance of the instruction pipelines can be obtained. The performance of asynchronous instruction pipelines can also be compared to synchronous case. Thus, one can decide the optimal design for instruction pipelines in asynchornous or synchronous cases and explore the deisng space of asynchronous instruction pipeline architectures
Body size and the risk of biliary tract cancer: a population-based study in China
Though obesity is an established risk factor for gall bladder cancer, its role in cancers of the extrahepatic bile ducts and ampulla of Vater is less clear, as also is the role of abdominal obesity. In a population-based case–control study of biliary tract cancer in Shanghai, China, odds ratios (ORs) and 95% confidence intervals (CIs) were calculated for biliary tract cancer in relation to anthropometric measures, including body mass index (BMI) at various ages and waist-to-hip ratio (WHR), adjusting for age, sex, and education. The study included 627 patients with biliary tract cancer (368 gall bladder, 191 bile duct, 68 ampulla of Vater) and 959 healthy subjects randomly selected from the population. A higher BMI at all ages, including early adulthood (ages 20–29 years), and a greater WHR were associated with an increased risk of gall bladder cancer. A high usual adult BMI (⩾25) was associated with a 1.6-fold risk of gall bladder cancer (95% CI 1.2–2.1, P for trend <0.001). Among subjects without gallstones, BMI was also positively associated with gall bladder cancer risk. Regardless of BMI levels, increasing WHR was associated with an excess risk of gall bladder cancer risk, with those having a high BMI (⩾25) and a high WHR (>0.90) having the highest risk of gall bladder cancer (OR=12.6, 95% CI 4.8–33.2), relative to those with a low BMI and WHR. We found no clear risk patterns for cancers of the bile duct and ampulla of Vater. These results suggest that both overall and abdominal obesity, including obesity in early adulthood, are associated with an increased risk of gall bladder cancer. The increasing prevalence of obesity and cholesterol stones in Shanghai seems at least partly responsible for the rising incidence of gall bladder cancer in Shanghai
A New Large Super-Fast Rotator: (335433) 2005 UW163
Asteroids of size larger than 150 m generally do not have rotation periods
smaller than 2.2 hours. This spin cutoff is believed to be due to the
gravitationally bound rubble-pile structures of the asteroids. Rotation with
periods exceeding this critical value will cause asteroid breakup. Up until
now, only one object, 2001 OE84, has been found to be an exception to this spin
cutoff. We report the discovery of a new super-fast rotator, (335433) 2005
UW163, spinning with a period of 1.290 hours and a lightcurve variation of
mag from the observations made at the P48 telescope and the P200
telescope of the Palomar Observatory. Its mag and
multi-band colors (i.e., mag, mag
and SDSS mag) show it is a V-type asteroid with a diameter of
km. This indicates (335433) 2005 UW163 is a super-fast rotator
beyond the regime of the small monolithic asteroid.Comment: 18 pages, 4 figures, 1 table Accepted by ApJ
A Bayesian measurement error model for two-channel cell-based RNAi data with replicates
RNA interference (RNAi) is an endogenous cellular process in which small
double-stranded RNAs lead to the destruction of mRNAs with complementary
nucleoside sequence. With the production of RNAi libraries, large-scale RNAi
screening in human cells can be conducted to identify unknown genes involved in
a biological pathway. One challenge researchers face is how to deal with the
multiple testing issue and the related false positive rate (FDR) and false
negative rate (FNR). This paper proposes a Bayesian hierarchical measurement
error model for the analysis of data from a two-channel RNAi high-throughput
experiment with replicates, in which both the activity of a particular
biological pathway and cell viability are monitored and the goal is to identify
short hair-pin RNAs (shRNAs) that affect the pathway activity without affecting
cell activity. Simulation studies demonstrate the flexibility and robustness of
the Bayesian method and the benefits of having replicates in the experiment.
This method is illustrated through analyzing the data from a RNAi
high-throughput screening that searches for cellular factors affecting HCV
replication without affecting cell viability; comparisons of the results from
this HCV study and some of those reported in the literature are included.Comment: Published in at http://dx.doi.org/10.1214/11-AOAS496 the Annals of
Applied Statistics (http://www.imstat.org/aoas/) by the Institute of
Mathematical Statistics (http://www.imstat.org
Allocating Scarce Resources Strategically - An Evaluation and Discussion of the Global Fund's Pattern of Disbursements
BACKGROUND: The Global Fund is under pressure to improve its rationing of financial support. This study describes the GF's pattern of disbursements in relation to total health expenditure (THE), government health expenditure (GHE), income status and the burden of HIV/AIDS, TB and malaria. It also examines the potential for recipient countries to increase domestic public financing for health. METHODS: This is a cross-sectional study of 104 countries that received Global Fund disbursements in 2009. It analyses data on Global Fund disbursements; health financing indicators; government revenue and expenditure; and burden of disease. FINDINGS: Global Fund disbursements made up 0.37% of THE across all 104 countries; but with considerable country variation ranging from 0.002% to 53.4%. Global Fund disbursements to government amounted to 0.47% of GHE across the 104 countries, but again with considerable variation (in three countries more than half of GHE was based on Global Fund support). Although the Global Fund provides progressively more funding for lower income countries on average, there is much variation at the country such that here was no correlation between per capita GF disbursements and per capita THE, nor between per capita GF disbursement to government and per capita GHE. There was only a slight positive correlation between per capita GF disbursement and burden of disease. Several countries with a high degree of 'financial dependency' upon the Fund have the potential to increase levels of domestic financing for health. DISCUSSION: The Global Fund can improve its targeting of resources so that it better matches the pattern of global need. To do this it needs to: a) reduce the extent to which funds are allocated on a demand-driven basis; and b) align its funding model to broader health systems financing and patterns of health expenditure beyond the three diseases
Asteroid Spin-Rate Study using the Intermediate Palomar Transient Factory
Two dedicated asteroid rotation-period surveys have been carried out using
data taken on January 6-9 and February 20-23 of 2014 by the Intermediate
Palomar Transient Factory (iPTF) in the ~band with -min cadence.
The total survey area covered 174~deg in the ecliptic plane. Reliable
rotation periods for 1,438 asteroids are obtained from a larger data set of
6,551 mostly main-belt asteroids, each with ~detections. Analysis of
1751, PTF based, reliable rotation periods clearly shows the "spin barrier" at
~hours for "rubble-pile" asteroids. We also found a new large-sized
super-fast rotator, 2005 UW163 (Chang et al., 2014), and other five candidates
as well. Our spin-rate distributions of asteroids with ~km shows
number decrease when frequency greater than 5 rev/day, which is consistent to
that of the Asteroid Light Curve Database (LCDB, Warner et al., 2009) and the
result of (Masiero et al., 2009). We found the discrepancy in the spin-rate
distribution between our result and (Pravec et al., 2008, update 2014-04-20) is
mainly from asteroids with mag that might be primarily due to
different survey strategies. For asteroids with ~km, we found a
significant number drop at rev/day. The YORP effect timescale for
small-sized asteroid is shorter that makes more elongate objets spun up to
reach their spin-rate limit and results in break-up. The K-S test suggests a
possible difference in the spin-rate distributions of C- and S-type asteroids.
We also find that C-type asteroids have a smaller spin-rate limit than the
S-type, which agrees with the general sense that the C-type has lower bulk
density than the S-type.Comment: Submitted to ApJ (Jan, 2015). Accepted by ApJ (June, 2015). The whole
set of the folded lightcurves will be available on the published articl
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