7,917 research outputs found
Recommended from our members
Ethnically Biased? Experimental Evidence from Kenya
Ethnicity has been shown to shape political, social, and economic behavior in Africa, but the underlying mechanisms remain contested. We utilize lab experiments to isolate one mechanism - an individual's bias in favor of coethnics and against non-coethnics - that has been central in both theory and in the conventional wisdom about the impact of ethnicity. We employ an unusually rich research design involving a large sample of 1300 participants from Nairobi, Kenya; the collection of multiple rounds of experimental data with varying proximity to national elections; within-lab priming conditions; both standard and novel experimental measures of coethnic bias; and an implicit association test (IAT). We find very little evidence of an ethnic bias in the behavioral games, which runs against the common presumption of extensive coethnic bias among ordinary Africans and suggests that mechanisms other than a coethnic bias in preferences must account for the associations we see in the region between ethnicity and political, social, and economic outcomes
Natural linewidth analysis of d-band photoemission from Ag(110)
We report a high-resolution angle-resolved study of photoemission linewidths
observed for Ag(110). A careful data analysis yields kdd\tau_h \geq 22
d$-hole dynamics in Cu (I.\
Campillo et al., Phys. Rev. Lett., in press) we interpret the lifetime
enhancement by a small scattering cross-section of - and -states below
the Fermi level. With increasing distance to the -hole lifetimes get
shorter because of the rapidly increasing density of d-states and contributions
of intra--band scattering processes, but remain clearly above
free-electron-model predictions.Comment: 14 pages, 7 figure
Prevalence of Rabbit Hemorrhagic Disease (RHD) in wild rabbits (Oryctolagus cuniculus) in Flanders, Belgium, 1999-2002
During the period of July 1999 through June 2002, carcasses of wild rabbits that had been shot or found dead and livers originating from wild rabbits that had been shot for consumption were collected in Flanders. One hundred and twelve carcasses were suitable for necropsy and histological and bacteriological analysis; histological analysis was possible in 41 livers. Considering the 112 rabbit carcasses only, Rabbit Hemorrhagic Disease (RHD) was found to be present in 33.9% of the cases. RHD was the most prevalent wild rabbit pathology detected in this study, before staphylococcosis (12.5%), and myxomatosis (10.7%). None of the liver samples from rabbits shot for consumption were positive for RHD. Of the 38 histologically RHD positive samples, 24 were analyzed with the hemagglutination (HA) technique, yielding 58.3% positive results. Seven samples that were histologically positive for RHD but HA negative were examined by transmission electron microscopy and were found positive for calicivirus. This proves that HA-negative RHD strains are circulating in the Flemish wild rabbit population
Strange Quark PDFs and Implications for Drell-Yan Boson Production at the LHC
Global analyses of Parton Distribution Functions (PDFs) have provided
incisive constraints on the up and down quark components of the proton, but
constraining the other flavor degrees of freedom is more challenging.
Higher-order theory predictions and new data sets have contributed to recent
improvements. Despite these efforts, the strange quark PDF has a sizable
uncertainty, particularly in the small x region. We examine the constraints
from experiment and theory, and investigate the impact of this uncertainty on
LHC observables. In particular, we study W/Z production to see how the s-quark
uncertainty propagates to these observables, and examine the extent to which
precise measurements at the LHC can provide additional information on the
proton flavor structure.Comment: 14 pages, 11 figures, added reference
Differential Effects of Krill Oil and Fish Oil on the Hepatic Transcriptome in Mice
Dietary supplementation with ω-3 polyunsaturated fatty acids (ω-3 PUFAs), specifically the fatty acids docosahexaenoic acid (DHA; 22:6 ω-3) and eicosapentaenoic acid (EPA; 20:5 ω-3), is known to have beneficial health effects including improvements in glucose and lipid homeostasis and modulation of inflammation. To evaluate the efficacy of two different sources of ω-3 PUFAs, we performed gene expression profiling in the liver of mice fed diets supplemented with either fish oil (FO) or krill oil (KO). We found that ω-3 PUFA supplements derived from a phospholipid krill fraction (KO) downregulated the activity of pathways involved in hepatic glucose production as well as lipid and cholesterol synthesis. The data also suggested that KO-supplementation increases the activity of the mitochondrial respiratory chain. Surprisingly, an equimolar dose of EPA and DHA derived from FO modulated fewer pathways than a KO-supplemented diet and did not modulate key metabolic pathways regulated by KO, including glucose metabolism, lipid metabolism and the mitochondrial respiratory chain. Moreover, FO upregulated the cholesterol synthesis pathway, which was the opposite effect of krill-supplementation. Neither diet elicited changes in plasma levels of lipids, glucose, or insulin, probably because the mice used in this study were young and were fed a low-fat diet. Further studies of KO-supplementation using animal models of metabolic disorders and/or diets with a higher level of fat may be required to observe these effects
Conflict-Free Coloring Made Stronger
In FOCS 2002, Even et al. showed that any set of discs in the plane can
be Conflict-Free colored with a total of at most colors. That is,
it can be colored with colors such that for any (covered) point
there is some disc whose color is distinct from all other colors of discs
containing . They also showed that this bound is asymptotically tight. In
this paper we prove the following stronger results:
\begin{enumerate} \item [(i)] Any set of discs in the plane can be
colored with a total of at most colors such that (a) for any
point that is covered by at least discs, there are at least
distinct discs each of which is colored by a color distinct from all other
discs containing and (b) for any point covered by at most discs,
all discs covering are colored distinctively. We call such a coloring a
{\em -Strong Conflict-Free} coloring. We extend this result to pseudo-discs
and arbitrary regions with linear union-complexity.
\item [(ii)] More generally, for families of simple closed Jordan regions
with union-complexity bounded by , we prove that there exists
a -Strong Conflict-Free coloring with at most colors.
\item [(iii)] We prove that any set of axis-parallel rectangles can be
-Strong Conflict-Free colored with at most colors.
\item [(iv)] We provide a general framework for -Strong Conflict-Free
coloring arbitrary hypergraphs. This framework relates the notion of -Strong
Conflict-Free coloring and the recently studied notion of -colorful
coloring. \end{enumerate}
All of our proofs are constructive. That is, there exist polynomial time
algorithms for computing such colorings
Ultrafast spatio-temporal dynamics of terahertz generation by ionizing two-color femtosecond pulses in gases
We present a combined theoretical and experimental study of spatio-temporal
propagation effects in terahertz (THz) generation in gases using two-color
ionizing laser pulses. The observed strong broadening of the THz spectra with
increasing gas pressure reveals the prominent role of spatio-temporal reshaping
and of a plasma-induced blue-shift of the pump pulses in the generation
process. Results obtained from (3+1)-dimensional simulations are in good
agreement with experimental findings and clarify the mechanisms responsible for
THz emission
- …