10,954 research outputs found
Parity-violating coupling constant from the flavor-conserving effective weak chiral Lagrangian
We investigate the parity-violating pion-nucleon-nucleon coupling constant
, based on the chiral quark-soliton model. We employ an effective
weak Hamiltonian that takes into account the next-to-leading order corrections
from QCD to the weak interactions at the quark level. Using the gradient
expansion, we derive the leading-order effective weak chiral Lagrangian with
the low-energy constants determined. The effective weak chiral Lagrangian is
incorporated in the chiral quark-soliton model to calculate the
parity-violating constant . We obtain a value of about
at the leading order. The corrections from the next-to-leading order
reduce the leading order result by about 20~\%.Comment: 12 page
Minimalist's Linux Cluster
Using barebone PC components and NIC's, we construct a linux cluster which
has 2-dimensional mesh structure. This cluster has smaller footprint, is less
expensive, and use less power compared to conventional linux cluster. Here, we
report our experience in building such a machine and discuss our current
lattice project on the machine.Comment: 3 pages, 2 figures, Proceedings of the Lattice 03 Conference
(Tsukuba, Japan
Labisia pumila extract protects skin cells from photoaging caused by UVB irradiation
Labisia pumila (Myrsinaceae), known as "Kacip Fatimah," has been used by many generations of Malay women to induce and facilitate child birth as well as a post partum medicine. However, its topical application on skin has not been reported yet. In this study, we have focused on the anti-photoaging effects of L. pumila. Extract of L. pumila was first analyzed for their antioxidant activities using DPPH (2,2-diphenyl-1-picrylhydrazyl) since UV irradiation is a primary cause of reactive oxygen species (ROS) generation in the skin. The 50% free radical scavenging activity (FSC(50)) of L. pumila extract was determined to be 0.006%, which was equal to that produced by 156 microM ascorbic acid. TNF-alpha and cyclooxygenase (COX-2) play a primary role in the inflammation process upon UV irradiation and are known to be stimulated by UVB. Treatment with L. pumila extract markedly inhibited the TNF-alpha production and the expression of COX-2. Decreased collagen synthesis of human fibroblasts by UVB was restored back to normal level after treatment with L. pumila extract. On the other hand, the enhanced MMP-1 expression upon UVB irradiation was down regulated by L. pumila extract in a dose-dependent manner. Furthermore, treatment of normal keratinocytes with L. pumila extract attenuated UVB-induced MMP-9 expression. These results collectively suggest L. pumila extract has tremendous potential as an anti-photoaging cosmetic ingredient
Effects of Rotation on Thermal-Gravitational Instability in the Protogalactic Disk Environment
Thermal-gravitational instability (TGI) is studied in the protogalactic
environment. We extend our previous work, where we found that dense clumps
first form out of hot background gas by thermal instability and later a small
fraction of them grow to virialized clouds of mass M_c >~ 6X10^6 M_sun by
gravitational infall and merging. But these clouds have large angular momentum,
so they would be difficult, if not impossible, to further evolve into globular
clusters. In this paper, through three-dimensional hydrodynamic simulations in
a uniformly rotating frame, we explore if the Coriolis force due to rotation in
protogalactic disk regions can hinder binary merging and reduce angular
momentum of the clouds formed. With rotation comparable to the Galactic
rotation at the Solar circle, the Coriolis force is smaller than the pressure
force during the early thermal instability stage. So the properties of clumps
formed by thermal instability are not affected noticeably by rotation, except
increased angular momentum. However, during later stage the Coriolis force
becomes dominant over the gravity, and hence the further growth to
gravitationally bound clouds by gravitational infall and merging is prohibited.
Our results show that the Coriolis force effectively destroys the picture of
cloud formation via TGI, rather than alleviate the problem of large angular
momentum.Comment: To appear in ApJ Lett. (June 1, 2006, v643n2). Pdf with full
resolution figures can be downloaded from
http://canopus.cnu.ac.kr/ryu/baeketal.pd
Three-Dimensional Numerical Simulations of Thermal-Gravitational Instability in Protogalactic Halo Environment
We study thermal-gravitational instability in simplified models for
protogalactic halos using three-dimensional hydrodynamic simulations. The
simulations followed the evolution of gas with radiative cooling down to T =
10^4 K, background heating, and self-gravity. Then cooled and condensed clouds
were identified and their physical properties were examined in detail. During
early stage clouds start to form around initial density peaks by thermal
instability. Small clouds appear first and they are pressure-bound.
Subsequently, the clouds grow through compression by the background pressure as
well as gravitational infall. During late stage cloud-cloud collisions become
important, and clouds grow mostly through gravitational merging.
Gravitationally bound clouds with mass M_c > ~6 X 10^6 Msun are found in the
late stage. They are approximately in virial equilibrium and have radius R_c =
\~150 - 200 pc. Those clouds have gained angular momentum through tidal torque
as well as merging, so they have large angular momentum with the spin parameter
~ 0.3. The clouds formed in a denser background tend to have smaller
spin parameters. We discuss briefly the implications of our results on the
formation of protoglobular cluster clouds in protogalactic halos. (abridged)Comment: To appear in ApJ 20 September 2005, v631 1 issue. Pdf with full
resolution figures can be downloaded from
http://canopus.cnu.ac.kr/ryu/baeketal.pd
Surveillance of Aedes aegypti and Aedes albopictus in the State of Illinois
Mosquito communities were actively sampled using a variety of traps in 8 counties in south-eastern Illinois with the intent to detect whether Aedes albopictusand Ae. aegypti were present in these locations.Specimens collected through routine surveillance and shared by 8 local public health departments or mosquito abatement districts were also identified to species to detect the presence of this species across a wider range of counties. While Ae. albopictus was found to be present in all of the 8 counties actively sampled (providing the first records of occurrence for these locations) and for 6 of the counties for which we received collections, the numbers of Ae. albopictus collected differed among locations. Culex spp. mosquitoes were also caught in the traps. Aedes aegypti was not found to be present in these locations. All collected Aedes and Culex spp. were screened for 6arboviruses, though no positives were found. By sequencing a segment of the mitochondrial CO1 gene of a subset of female Ae. albopictus from 10 locations in Illinois we identified 17 unique genetic sequences (haplotypes), with likely at least 4 distinct genetic lineages being present in Illinois, with different geographic areas having distinct genetic populations. This suggests that the composition of this vector species in Illinois is the result of a complex and dynamic invasion history. Major questions for future work are how these genetic differences relate to the increase in abundance of Ae. albopictus in recent years, and whether there are phenotypic differences among these populations that might impact the epidemiology of vector-borne diseases in Illinois.Illinois Department of Public Healthunpublishednot peer reviewedOpe
Controlled Korean for Korean-English MT
PACLIC / The University of the Philippines Visayas Cebu College Cebu City, Philippines / November 20-22, 200
Insecticide Resistance Surveillance of a Zika Virus Vector, Aedes albopictus, in the State of Illinois
The extent to which populations of two vector species in Illinois, the Asian tiger mosquito, Aedes albopictus, and the northern house mosquito, Culex pipiens, remain sensitive to two commonly-used insecticides (permethrin and malathion) was investigated using a series of CDC bottle assays.For Ae. albopictus, 6 colonies were established from collections in central and southern Illinois, while for Cx. pipiens eggs were collected in the North Shore of Cook County.The results suggest that the time until death occurred was longer in several of the more southern field populations for Ae. albopictus than that of a sensitive reference strain, for both malathion and permethrin at the recommended diagnostic dose. At a lower concentration of malathion,however,field populations appeared more sensitive than the reference strain.Further work will be required to confirm whether these conflicting results reflect environmental noise or a true genetic difference in the sensitivity status of these populations.The time until death occurred was also longer in field-collected Cx. pipiens than that of a sensitive reference strainwhen exposed to three different concentrations of permethrin. The results of this initial insecticide resistance survey thus suggest that insecticide sensitivity varies among populations. Confirmation of and expansion on these results, through additional bioassays, inclusion of additional populations across Illinois, elucidation of the physiological mechanisms involved, and investigations performed over time will be required to develop a thorough understanding of the threat to public health associated with potentially increasing levels of resistance in IL mosquito populations.Illinois Department of Public Healthunpublishednot peer reviewedOpe
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