931 research outputs found
Dr. Mihailo Pavlović, Značajni predstavnici francuskog romana između dva svetska rata (Le roman français entre les deux guerres), Beograd, 1965, Zavod za izdavanje udžbenika Socijalističke Republike Srbije, pp. 179
Dr. Mihailo Pavlović, Značajni predstavnici francuskog romana između dva svetska rata (Le roman français entre les deux guerres), Beograd, 1965, Zavod za izdavanje udžbenika Socijalističke Republike Srbije, pp. 17
A New RL Constant for the Calculation of log P and n Values in Congeneric Compounds
Retention volumes of iodinated diethylstilbestrols and estradiols
measured by high-pressure liquid chromatography on a silica
column were found to be linearly related to their experimental
partition coefficients (log P). The log P values calculated from the
new RL parameter correlate well with experimental values and with
those calculated by Hansch :n:-constants. The magnitudes of it-values
for iodine in monosubstituted estradiols are discussed in terms of
the contribution of steric and »proximity« effects to these constants.
The reported technique may be a significant addition to the
methodology of obtaining lipophylic-hydrophylic constants in structure-
activity relationship studies
Working Memory and Behavioral Inhibition in Attention-deficit/hyperactivity Disorder: A Re-examination of Competing Core Processes
Working memory and behavioral inhibition have been identified as potential underlying deficits of attention-deficit/hyperactivity disorder (ADHD) in competing models of the disorder. The stop-signal (SS) paradigm is often reified as a measure of behavioral inhibition across ADHD research. However, the choice reaction time component of the SS task likely places demands on working memory processes, consequently confounding the paradigm as a pure measure of inhibition. Therefore, the current study examined the relationship between multiple inhibition tasks to test competing models of ADHD. Forty-six boys, between 8 to 12 years old, with and without ADHD, were administered working memory (phonological and visuospatial tasks) and behavioral inhibition (go/no-go and SS) tasks. Bias-corrected bootstrapped mediation analyses indicated that working memory accounted for the relationship between group membership (ADHD and typically developing children) and both measures of inhibition. In contrast, only SS inhibition mediated the relationship between group and working memory. Overall, these findings suggest that studies that use the SS paradigm may be confounded by controlled-focused attention associated with the choice-reaction time element of the stop-signal task. Additional research that utilizes alternative measures of behavioral inhibition is needed to determine the extent of the overlap in children with the disorder.Psycholog
Constraints on the Intergalactic Transport of Cosmic Rays
Motivated by recent experimental proposals to search for extragalactic cosmic
rays (including anti-matter from distant galaxies), we study particle
propagation through the intergalactic medium (IGM). We first use estimates of
the magnetic field strength between galaxies to constrain the mean free path
for diffusion of particles through the IGM. We then develop a simple analytic
model to describe the diffusion of cosmic rays. Given the current age of
galaxies, our results indicate that, in reasonable models, a completely
negligible number of particles can enter our Galaxy from distances greater than
Mpc for relatively low energies ( GeV/n). We also find
that particle destruction in galaxies along the diffusion path produces an
exponential suppression of the possible flux of extragalactic cosmic rays.
Finally, we use gamma ray constraints to argue that the distance to any
hypothetical domains of anti-matter must be roughly comparable to the horizon
scale.Comment: 24 pages, AAS LaTex, 1 figure, accepted to Ap
Stem Cells Derived from Tooth Periodontal Ligament Enhance Functional Angiogenesis by Endothelial Cells
In regenerative medicine approaches involving cell therapy, selection of the appropriate cell type is important in that the cells must directly (differentiation) or indirectly (trophic effects) participate in the regenerative response. Regardless of the mode of action of the cells, angiogenesis underlies the success of these approaches. Stem cells derived from tooth tissues, specifically the periodontal ligament of teeth (periodontal ligament stem cells [PDLSCs]), have recently been identified as a good source of multipotent cells for cell therapies. PDLSCs have demonstrated properties similar to mesenchymal stem cells (MSCs), yet, unlike MSCs, their vascular potential has not been previously demonstrated. Thus, the aim of this study was to determine if PDLSCs could modulate angiogenesis. In comparison to MSCs and stem cells derived from tooth pulp tissues (SHEDs), we first determined if PDLSCs released soluble proangiogenic factors with the capacity to induce vessel formation by endothelial cells (ECs). Next, the ability of PDLSCs to modulate angiogenesis was examined through their cotransplantation with ECs in subcutaneous sites of immunocompromised mice. Finally, the stability of the PDLSC-mediated vasculature was determined through evaluation of the maturity and functionality of the vessels formed following PDLSC transplantation. It was determined that PDLSCs produced appreciable levels of vascular endothelial growth factor and basic fibroblast growth factor-2, and additionally, were able to initiate in vitro angiogenesis of ECs comparable to MSC- and SHED-mediated angiogenesis. In vivo cotransplantation of ECs with PDLSCs significantly (>50% increase) enhanced the number of blood vessels formed relative to transplantation of ECs alone. Finally, vessels formed following PDLSC cotransplantation were more mature and less permeable than those formed after transplantation of EC alone. These data demonstrate for the first time that PDLSCs have vascular potential, which could make them a very attractive cell population for utilization in regenerative cell therapies.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/140229/1/ten.tea.2013.0512.pd
A New RL Constant for the Calculation of log P and n Values in Congeneric Compounds
Retention volumes of iodinated diethylstilbestrols and estradiols
measured by high-pressure liquid chromatography on a silica
column were found to be linearly related to their experimental
partition coefficients (log P). The log P values calculated from the
new RL parameter correlate well with experimental values and with
those calculated by Hansch :n:-constants. The magnitudes of it-values
for iodine in monosubstituted estradiols are discussed in terms of
the contribution of steric and »proximity« effects to these constants.
The reported technique may be a significant addition to the
methodology of obtaining lipophylic-hydrophylic constants in structure-
activity relationship studies
Aromatic Iodination of Diethylstilbestrol Diphosphate
Sterically crowded estrogenic compound diethylstilbestrol
diphosphate was successfully polyiodinated on the aromatic rings
applying an electrochemical procedure. The reported synthesis
also opens the way for the preparation of potentially useful radiolabelled
cancer chemotherapeutics
Unbiased clustering estimates with the DESI fibre assignment
The Emission Line Galaxy survey made by the Dark Energy Spectroscopic
Instrument (DESI) survey will be created from five passes of the instrument on
the sky. On each pass, the constrained mobility of the ends of the fibres in
the DESI focal plane means that the angular-distribution of targets that can be
observed is limited. Thus, the clustering of samples constructed using a
limited number of passes will be strongly affected by missing targets. In two
recent papers, we showed how the effect of missing galaxies can be corrected
when calculating the correlation function using a weighting scheme for pairs.
Using mock galaxy catalogues we now show that this method provides an unbiased
estimator of the true correlation function for the DESI survey after any number
of passes. We use multiple mocks to determine the expected errors given one to
four passes, compared to an idealised survey observing an equivalent number of
randomly selected targets. On BAO scales, we find that the error is a factor 2
worse after one pass, but that after three or more passes, the errors are very
similar. Thus we find that the fibre assignment strategy enforced by the design
of DESI will not affect the cosmological measurements to be made by the survey,
and can be removed as a potential risk for this experiment.Comment: 11 pages, 8 figure
Status of cosmic-ray antideuteron searches
The precise measurement of cosmic-ray antiparticles serves as important means
for identifying the nature of dark matter. Recent years showed that identifying
the nature of dark matter with cosmic-ray positrons and higher energy
antiprotons is difficult, and has lead to a significantly increased interest in
cosmic-ray antideuteron searches. Antideuterons may also be generated in dark
matter annihilations or decays, offering a potential breakthrough in unexplored
phase space for dark matter. Low-energy antideuterons are an important approach
because the flux from dark matter interactions exceeds the background flux by
more than two orders of magnitude in the low-energy range for a wide variety of
models. This review is based on the "dbar14 - dedicated cosmic-ray antideuteron
workshop", which brought together theorists and experimentalists in the field
to discuss the current status, perspectives, and challenges for cosmic-ray
antideuteron searches and discusses the motivation for antideuteron searches,
the theoretical and experimental uncertainties of antideuteron production and
propagation in our Galaxy, as well as give an experimental cosmic-ray
antideuteron search status update. This report is a condensed summary of the
article "Review of the theoretical and experimental status of dark matter
identification with cosmic-ray antideuteron" (arXiv:1505.07785).Comment: 9 pages, 4 figures, ICRC 2015 proceeding
- …