240 research outputs found
Evaporation of a black hole off of a tense brane
We calculate the gray-body factors for scalar, vector and graviton fields in
the background of an exact black hole localized on a tensional 3-brane in a
world with two large extra dimensions. Finite brane tension modifies the
standard results for the case with of a black hole on a brane with negligible
tension. For a black hole of a fixed mass, the power carried away into the bulk
diminishes as the tension increases, because the effective Planck constant, and
therefore entropy of a fixed mass black hole, increase. In this limit, the
semiclassical description of black hole decay becomes more reliable.Comment: a few typos corrected, accepted for publication in PR
Murine brain endothelial cells differently modulate interferon-γ and interleukin-17 production in vitro
Brain endothelial cells (BEC) are the major constituents of the blood-brain barrier (BBB), the structure that controls entrance of immune cells into CNS parenchyma. Our aim was to investigate the influence of BEC on production of IL-17 and IFN-γ-cytokines that are important for CNS inflammation. To that end, co-cultivations of the bEnd.3 brain endothelial cell line and lymph node cells (LNC) were performed, and gene expression and production of IL-17 and IFN-γ were determined. It was found that bEnd.3 cells inhibited expression and production of IFN-γ, but not of IL-17. Additionally, bEnd.3 cells also reduced production of the major IFN-γ-promoting cytokine - IL-12 - in LNC. The observed variation in modulation of pro-inflammatory cytokines by BEC could be of importance for the understanding of CNS inflammation
Theory of the Optical Conductivity in the Cuprate Superconductors
We present a study of the normal state optical conductivity in the cuprate
superconductors using the nearly antiferromagnetic Fermi liquid (NAFL)
description of the magnetic interaction between their planar quasiparticles. We
find that the highly anisotropic scattering rate in different regions of the
Brillouin zone, both as a function of frequency and temperature, a benchmark of
NAFL theory, leads to an average relaxation rate of the Marginal Fermi Liquid
form for overdoped and optimally doped systems, as well as for underdoped
systems at high temperatures. We carry out numerical calculations of the
optical conductivity for several compounds for which the input spin fluctuation
parameters are known. Our results, which are in agreement with experiment on
both overdoped and optimally doped systems, show that NAFL theory explains the
anomalous optical behavior found in these cuprate superconductors.Comment: REVTEX file, 8 PostScript figure
Assessment of the nucleotide modifications in the high-resolution cryo-electron microscopy structure of the Escherichia coli 50S subunit.
Post-transcriptional ribosomal RNA (rRNA) modifications are present in all organisms, but their exact functional roles and positions are yet to be fully characterized. Modified nucleotides have been implicated in the stabilization of RNA structure and regulation of ribosome biogenesis and protein synthesis. In some instances, rRNA modifications can confer antibiotic resistance. High-resolution ribosome structures are thus necessary for precise determination of modified nucleotides' positions, a task that has previously been accomplished by X-ray crystallography. Here, we present a cryo-electron microscopy (cryo-EM) structure of the Escherichia coli 50S subunit at an average resolution of 2.2 Å as an additional approach for mapping modification sites. Our structure confirms known modifications present in 23S rRNA and additionally allows for localization of Mg2+ ions and their coordinated water molecules. Using our cryo-EM structure as a testbed, we developed a program for assessment of cryo-EM map quality. This program can be easily used on any RNA-containing cryo-EM structure, and an associated Coot plugin allows for visualization of validated modifications, making it highly accessible
Drama hero in modern Serbian literature (1890-1918)
У намери да понудимо прецизну и убедљиву слику епохе, односно позицију
драмске књижевности у њој, у фокус интересовања постављен је драмски јунак,
преко кога смо посредно осветлили и друге аспекте дела условљене његовом
егзистенцијом, ломовима, сукобима и хтењима. Сам јунак је постао оличење
сукоба и чувар граничности између два сукобљена света, а неретко и знамен
подвојености.
Како је концепт јунака условљен правилима жанра, покушали смо да путем
жанровске класификације осветлимо различите типове јунака као носиоце и
реализаторе пишчевих идеја. Међутим, док се, са једне стране, у традиционалним
врстама јунак прилагођава жанру, дотле је, на другој страни, сам јунак, као човек
преузет из стварности онога времена, управо захваљујући таквој стварности
транспонованој у књижевноуметнички свет, условио настанак појединих нових
драмских врста.
Узвишени и врлинама обдарени јунак трагедије и историјске драме је,
силазећи са тих висина, све више постајао пишчев савременик, маргинализован и
неспреман за борбу са животом. Такав јунак се све више испољавао као играчка
случаја и носилац унутрашње трагике која се манифестовала као трајни раскол
између унутрашњег и спољног света, између његовог јавног и приватног бића...In order to offer a precise and convincing image of the epoch, that is, the position
of drama in it, the focus of our interests was positioned on the drama hero, by means of
whom we indirectly shed light on other aspects of the work conditioned by the hero’s
existence, ambiguities, conflicts and desires. The hero themselves became the
embodiment of conflict and the guardian of the border between two competing worlds,
and often a sign of ambivalence.
Since the concept of a hero is conditioned by the rules of the genre, we tried to
illuminate different types of heroes as the carriers and agents of the writer’s ideas by
using genre classifications. However, on the one hand, in the traditional types, the hero
adapts to the genre in question, the hero themselves, on the other hand, as a human
being taken from the reality of that time, conditioned the emergence of some new types
of drama, precisely owing to such reality which is transported into the literary and
artistic world.
An exalted and virtue-endowed hero of a tragedy and historical drama, by
descending from these heights, was increasingly becoming the writer’s contemporary
marginalized and unprepared for a fight with life. Such a hero demonstrated themselves
more and more as a toy of the case and a carrier of internal tragedy which was
manifested as a permanent dissidence between the inner and outer world, between its
public and private being..
Weak Pseudogap Behavior in the Underdoped Cuprate Superconductors
We report on an exact solution of the nearly antiferromagnetic Fermi liquid
spin fermion model in the limit \pi T << \omega_{sf}, which demonstrates that
the broad high energy features found in ARPES measurements of the spectral
density of the underdoped cuprate superconductors are determined by strong
antiferromagnetic (AF) correlations and precursor effects of an SDW state. We
show that the onset temperature, T^{cr}, of weak pseudo-gap (pseudoscaling)
behavior is determined by the strength, \xi, of the AF correlations, and obtain
the generic changes in low frequency magnetic behavior seen in NMR experiments
with \xi(T^{cr}) \approx 2, confirming the Barzykin and Pines crossover
criterion.Comment: REVTEX, 4 pages, 3 EPS figure
Pentoxifylline Prevents Autoimmune Mediated Inflammation in Low Dose Streptozotocin Induced Diabetes
Xanthine derivative, pentoxifylline (PTX), has been recently shown to exert a protective effects
in certain animal models of autoimmunity, including diabetes in NOD mice. In the present
study, the immunomodulatory potential of PTX was investigated in autoimmune diabetes
induced by multiple low doses of streptozotocin (MLD-SZ) in genetically susceptible CBA/H
mice (tested with 40 mg SZ/kg b.w. for 5 days) and DA rats (tested with 20 mg/kg b.w. for 5
days). In both species, 2 – 3 weeks following the MLD-SZ treatment, sustained hyperglycemia
developed, as an outcome of inflammatory reaction with endothelial cell activation and accumulation
of mononuclear cells. Although there was no evidence of typical insulitis in early disease
development (day 10), in both rats and mice, macrophages, CD4+ and CD8+ cells were present in the islets of Langerhans as diffuse mononuclear infiltrates with the expression of
IFN-γ and inducible NO synthase (iNOS). Administration of PTX (200 mg/kg/day for 10 days)
in combination with MLD-SZ reduced insulitis and the production of mediators tested, and prevented
the development of hyperglycemia. These results suggest that beneficial effects of PTX
involve down-regulation of local proinflammatory cytokine-mediated NO synthase pathway.
They also demonstrate that in addition to ameliorating spontaneous autoimmunity in NOD
mice, PTX may be effective in downregulating an inflammatory autoimmune process triggered
in susceptible host by an external agents, such as streptozotocin
STR loci D19S216, D20S502 and D20S842 analysis in the Serbian population using dentin DNA
Dentin provides a protective enclosure for genomic and mitochondrial DNA. In the present study, DNA was obtained from pulverized or ground teeth. The quality of the DNA extracted from the teeth of 70 unrelated individuals was tested in the context of assessing the allelic and genotypic frequencies of autosomal loci D19S216, D20S502 and D20S842, and calculating a number of parameters of population genetics and forensic interest. This study illustrates that teeth can be a convenient tissue to extract DNA from large numbers of individuals for population genetic studies as well as for forensic case work
Rat duodenal motility in vitro: Prokinetic effects of DL-homocysteine thiolactone and modulation of nitric oxide mediated inhibition
Homocysteine is a significant but modifiable risk factor for vascular
diseases. As gastrointestinal smooth musculature is similar to blood vessel
muscles, we investigated how elevated homocysteine levels affect nitric
oxide-mediated neurotransmission in the gut. There is accumulated evidence
that a dysfunction of NO neurons in the myenteric plexus may cause various
diseases in the gastrointestinal tract such as achalasia, diabetic
gastroparesis and infantile hypertrophic pyloric stenosis. In the present
study, we aimed to assess the effects of homocysteine on NO-mediated
responses in vitro, and to examine the effects of DL-homocysteine thiolactone
on the spontaneous motility of rat duodenum and nitrergic neurotransmission.
DL-homocysteine thiolactone concentration of 10 μmol/L leads to the immediate
increase in tone, amplitude and frequency of spontaneous movements in
isolated rat duodenum. L-NAME (30 μmol/L) leads to an increase in basal tone,
amplitude and frequency of spontaneous contractions. The relaxations induced
by EFS were significantly reduced in duodenal segments incubated in
DL-homocysteine thiolactone compared with the control group. EFS-induced
relaxations were inhibited by L-NAME in both experimental and control groups.
These results suggest that a high level of homocysteine causes an important
impairment of non-adrenergic non-cholinergic innervation of the rat duodenum.
[Projekat Ministarstva nauke Republike Srbije, br. 175043
KOMPETENCIJE ODGAJATELJA ZA RJEŠAVANJE SUKOBA U UČENIČKOM DOMU
U ovom radu predstavljeni su rezultati empirijske studije koja je imala za cilj ispitati stavove domskih odgajatelja o njihovim kompetencijama za rješavanje sukoba među učenicima. Istraživanje je provedeno u studentskim domovima u Srbiji, na uzorku od 61 odgajatelj, 28 odgajatelja i 33 odgajateljice. Za ispitivanje stavova odgajatelja koristili smo instrument N. Suzić [1], koji smo prilagodili za potrebe ovog istraživanja. Rezultati koje smo dobili pokazuju da odgajatelji imaju sve potrebne kompetencije za posredovanje u sukobima među učenicima i da prepoznaju da je njihova uloga u rješavanju sukoba među učenicima relevantna. Osim što odgajatelji navode da posjeduju potrebne kompetencije za posredovanje u sukobima među učenicima, potrebno je posvetiti više pozornosti sukobima u domovima učenika i kompetencijama odgajatelja za njihovo rješavanje
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