5,044 research outputs found
Environmental Dependence of Local Luminous Infrared Galaxies
We study the environmental dependence of local luminous infrared galaxies
(LIRGs) and ultraluminous infrared galaxies (ULIRGs) found in the Sloan Digital
Sky Survey (SDSS) data. The LIRG and ULIRG samples are constructed by
cross-correlating spectroscopic catalogs of galaxies of the SDSS Data Release 7
and the Infrared Astronomical Satellite Faint Source Catalog. We examine the
effects of the large-scale background density (Sigma_5), galaxy clusters, and
the nearest neighbor galaxy on the properties of infrared galaxies (IRGs). We
find that the fraction of LIRGs plus ULIRGs among IRGs (f_(U)LIRGs) and the
infrared luminosity (L_IR) of IRGs strongly depend on the morphology of and the
distance to the nearest neighbor galaxy: the probability for an IRG to be a
(U)LIRG (f_(U)LIRGs) and its L_IR both increase as it approaches a late-type
galaxy, but decrease as it approaches an early-type galaxy (within half the
virial radius of its neighbor). We find no dependence of f_(U)LIRGs on the
background density (surface galaxy number density) at fixed stellar mass of
galaxies. The dependence of f_(U)LIRGs on the distance to galaxy clusters is
also found to be very weak, but in highest-density regions such as the center
of galaxy clusters, few (U)LIRGs are found. These environmental dependence of
LIRGs and ULIRGs and the evolution of star formation rate (SFR)-environment
relation from high redshifts to low redshifts seem to support the idea that
galaxy-galaxy interactions/merging play a critical role in triggering the star
formation activity of LIRGs and ULIRGs.Comment: 14 pages, 17 figures. To appear in A&A. Paper with high resolution
figures is available at
http://astro.kias.re.kr/~hshwang/doc/ms_hwang_lirg.pd
``Superfast'' Reaction in Turbulent Flow with Potential Disorder
We explore the regime of ``superfast'' reactivity that has been predicted to
occur in turbulent flow in the presence of potential disorder. Computer
simulation studies confirm qualitative features of the previous renormalization
group predictions, which were based on a static model of turbulence. New
renormalization group calculations for a more realistic, dynamic model of
turbulence show that the superfast regime persists. This regime, with
concentration decay exponents greater than that for a well-mixed reaction,
appears to be a general result of the interplay among non-linear reaction
kinetics, turbulent transport, and local trapping by potential disorder.Comment: 14 pages. 4 figures. Uses IOP styles. To appear in J. Phys. A: Math.
Ge
Reactive Turbulent Flow in Low-Dimensional, Disordered Media
We analyze the reactions and
occurring in a model of turbulent flow in two dimensions. We find the reactant
concentrations at long times, using a field-theoretic renormalization group
analysis. We find a variety of interesting behavior, including, in the presence
of potential disorder, decay rates faster than that for well-mixed reactions.Comment: 6 pages, 4 figures. To appear in Phys. Rev.
A Meta-Analysis on the Effectiveness of Computer-Based Education in Nursing
Objectives: The purpose of this study was to conduct a comparative analysis of education effectiveness between computerbased education and traditional education methods in nursing. Methods: Medical and nursing literature databases were searched to identify studies regarding the effectiveness of computer-based education in nursing. Overall effect sizes for three outcome variables (knowledge, attitude, and practice level) were calculated. The effects of study characteristics on the outcome variables were analyzed. Results: Twenty-seven studies published from 1990 to February 2009, which that met the inclusion criteria, were included in the analysis. The meta-analysis showed that computer-based education generally had positive effects on knowledge, attitude, and practice, with overall effect sizes of 0.43, 0.35, and 0.34, respectively. This study also showed that the type of learner and the total education period had different effects on knowledge. Conclusions: This metaanalysis found that computer-based education in nursing had positive effects on knowledge, attitude, and practice. Keywords: Meta-analysis, Computer-based, Education, Nursing I
Identification of regulatory network hubs that control lipid metabolism in Chlamydomonas reinhardtii
HighlightCharacterization of regulatory networks in Chlamydomonas reinhardtii led to the identification of regulatory hubs that control the repatterning of cellular metabolism that leads to triacylglycerol accumulation in microalgae.Microalgae-based biofuels are promising sources of alternative energy, but improvements throughout the production process are required to establish them as economically feasible. One of the most influential improvements would be a significant increase in lipid yields, which could be achieved by altering the regulation of lipid biosynthesis and accumulation. Chlamydomonas reinhardtii accumulates oil (triacylglycerols, TAG) in response to nitrogen (N) deprivation. Although a few important regulatory genes have been identified that are involved in controlling this process, a global understanding of the larger regulatory network has not been developed. In order to uncover this network in this species, a combined omics (transcriptomic, proteomic and metabolomic) analysis was applied to cells grown in a time course experiment after a shift from N-replete to N-depleted conditions. Changes in transcript and protein levels of 414 predicted transcription factors (TFs) and transcriptional regulators (TRs) were monitored relative to other genes. The TF and TR genes were thus classified by two separate measures: up-regulated versus down-regulated and early response versus late response relative to two phases of polar lipid synthesis (before and after TAG biosynthesis initiation). Lipidomic and primary metabolite profiling generated compound accumulation levels that were integrated with the transcript dataset and TF profiling to produce a transcriptional regulatory network. Evaluation of this proposed regulatory network led to the identification of several regulatory hubs that control many aspects of cellular metabolism, from N assimilation and metabolism, to central metabolism, photosynthesis and lipid metabolism
Polymorphisms of High-Affinity IgE Receptor and Histamine-Related Genes in Patients with ASA-Induced Urticaria/Angioedema
The pathogenic mechanism of ASA-induced urticaria/angioedema (AIU) is still poorly understood, but it has been known that histamine releasing by cutaneous mast cell activation is considered to be an important role. Considering the importance of histamine in AIU, we speculated that a genetic abnormality of histamine-related genes such as a high-affinity IgE receptor, a metabolic enzyme of histamines and histamine receptors, may be involved in the development of AIU. Enrolled in the study were 110 patients with AIU, 53 patients without ASA hypersensitivity who had various drug allergies presenting as exanthematous skin symptoms, and 99 normal healthy controls (NC). Eleven single nucleotide polymorphisms (SNPs) of the β chain of the high-affinity IgE receptor (FCER1B) and three histamine-related genes-histamine N-methyltransferase (HNMT), histamine H1 receptor (HRH1), histamine H2 receptor (HRH2)-were screened using the SNP-IT assay based on a single base extension method. No significant differences were observed in allele and genotype frequencies, and haplotype frequencies of all the SNPs of FCER1B, HNMT, HRH1, and HRH2 among the three groups (p>0.05, respectively). These results suggest that the polymorphisms of FCER1B and the three histamine-related genes may not contribute to the development of AIU phenotype in the Korean population
The Inhibitory Effect of siRNAs on The High Glucose-Induced Overexpression of TGF-β1 in Mesangial Cells
Diabetic nephropathy is characterized by an expansion of the glomerular mesangium, caused by mesangial cell proliferation and an excessive accumulation of extracellar matrix (ECM) proteins, which eventually leading to glomerulosclerosis. TGF-β1 was found to play an important role in the accumulation of ECM in the kidney. In this study, TGF-β1 RNA interference was used as an effective therapeutic strategy. The inhibitory effect of TGF-β1 small interfering RNAs (siRNAs) on the high glucose-induced overexpression of TGF-β1 in rat mesangial ceys (RMCs). A high levels of glucose induces TGF-β1 mRNA and protein, and TGF-β1 siRNAs reduce the ability of high glucose to stimulate their expression. We also examined the inhibitory effect of TGF-β1 siRNAs on the expression of plasminogen activator inhibitor (PAI)-1 and Collagen Type I which are down-regulators of TGF-β1. The expression of TGF-β1, PAI-1 and Collagen Type I was increased in RMCs that were stimulated by 30 mM glucose. TGF-β1 siRNAs reduces high glucose-induced TGF-β1, PAI-1, and Collagen Type I mRNA and protein expression in a dose-dependent manner. In conclusion, the present study demonstrates that TGF-β1 siRNAs effectively inhibits TGF-β1 mRNA and protein expression in RMCs. These suggest that TGF-β1 siRNAs through RNAi may be a useful tool for developing new therapeutic applications for the treatment of diabetic nephropathy
Multiphase segregation and metal-insulator transition in single crystal La(5/8-y)Pr(y)Ca(3/8)MnO3
The insulator-metal transition in single crystal La(5/8-y)Pr(y)Ca(3/8)MnO3
with y=0.35 was studied using synchrotron x-ray diffraction, electric
resistivity, magnetic susceptibility, and specific heat measurements. Despite
the dramatic drop in the resistivity at the insulator-metal transition
temperature Tmi, the charge-ordering (CO) peaks exhibit no anomaly at this
temperature and continue to grow below Tmi. Our data suggest then, that in
addition to the CO phase, another insulating phase is present below Tco. In
this picture, the insulator-metal transition is due to the changes within this
latter phase. The CO phase does not appear to play a major role in this
transition. We propose that a percolation-like insulator-metal transition
occurs via the growth of ferromagnetic metallic domains within the parts of the
sample that do not exhibit charge ordering. Finally, we find that the
low-temperature phase-separated state is unstable against x-ray irradiation,
which destroys the CO phase at low temperatures.Comment: 9 pages, 9 encapsulated eps figure
Effect of Antisense TGF-β1 Oligodeoxynucleotides in Streptozotocin-Induced Diabetic Rat Kidney
Transforming growth factor (TGF)-β1 is an important fibrogenic factor that is involved in the pathogenesis of diabetic nephropathy. We evaluated the effect of circular antisense TGF-β1 oligodeoxynucleotides (ODNs) on the TGF-β1 expression in the rat mesangial cell culture and in streptozotocin (STZ)-induced diabetic rats. Circular antisense TGF-β1 ODNs were found to be stable in rat serum, significantly decreasing TGF-β1 mRNA expression compared with linear antisense ODNs in the rat mesangial cell culture. Circular antisense TGF-β1 ODNs were introduced into the tail vein of normal rats using hemagglutinating virus of Japan (HVJ)-liposome-mediated gene transfer method and were confirmed to be delivered effectively into the kidney, liver, lungs, and spleen. To inhibit the overexpression of TGF-β1 in diabetic kidneys, we introduced circular antisense TGF-β1 ODNs into the STZ-induced diabetic rats. On day 13 after circular antisense TGF-β1 ODNs injection, TGF-β1 mRNA and protein expression markedly decreased and urinary TGF-β1 excretion rate also dropped in the circular antisense TGF-β1 ODNs-treated diabetic rats. These results suggest that circular antisense TGF-β1 ODNs may be a useful tool for developing new therapeutic application for progressive diabetic nephropathy
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