5,859 research outputs found
N-(3,4-Dichlorophenyl)-3-oxobutanamide
In the title compound. C10H9Cl2NO2, the acetamide residue is twisted out of the phenyl ring plane by 25.40 (9)°. An intramolecular C—H⋯O close contact is observed. The N atom of the butanamide unit forms an intermolecular N—H⋯O hydrogen bond with the symmetry-related carbonyl O atom, interlinking molecules into a C(4) chain along [100]. Additional C—H⋯O intermolecular interactions and Cl⋯Cl contacts [3.4364 (8) Å] contribute to the stability of the crystal packing
Survival of Mycobacterium abscessus isolated from people with CF in artificially generated aerosols
M. abscessus survives aerosolisation suggesting airborne transmission between people with CF may occu
Traveling Wave Solutions in a Chain of Periodically Forced Coupled Nonlinear Oscillators
Motivated by earlier studies of artificial perceptions of light called phosphenes, we analyze traveling wave solutions in a chain of periodically forced coupled nonlinear oscillators modeling this phenomenon. We examine the discrete model problem in its co-traveling frame and systematically obtain the corresponding traveling waves in one spatial dimension. Direct numerical simulations as well as linear stability analysis are employed to reveal the parameter regions where the traveling waves are stable, and these waves are, in turn, connected to the standing waves analyzed in earlier work. We also consider a two-dimensional extension of the model and demonstrate the robust evolution and stability of planar fronts and annihilation of radial ones. Finally, we show that solutions that initially feature two symmetric fronts with bulged centers evolve in qualitative agreement with experimental observations of phosphenes
The decline in youth drinking in England – is everyone drinking less? A quantile regression analysis
Background and Aims: Youth alcohol consumption has declined significantly over the past 15 years in many high income countries, which may have significant public health benefits. However, if the reductions in drinking occur mostly among lighter drinkers who are at lower risk, then rates of alcohol-related harm among young people today and adults in future may not fall in line with consumption. There is conflicting evidence from Swedish school studies with some suggesting all young people are drinking less while others suggest alcohol consumption among heavier drinkers may be stable or rising while average consumption declines. This paper extends the geographic focus of previous research and examines whether the decline in youth drinking is consistent across the consumption distribution in England.
Design: Quantile regression of 15 waves of repeat cross-sectional survey data.
Setting: England, 2001-2016.
Participants: 31, 882 schoolchildren (50.7% male) aged 11-15 who responded to the Smoking Drinking and Drug Use amongst Young People surveys.
Measurements: Past-week alcohol consumption in UK units at each fifth percentile of the consumption distribution.
Findings: Reductions in alcohol consumption occurred at all percentiles of the consumption distribution analysed between 2001 and 2016 but the magnitude of the decline differed across percentiles. The decline in consumption at the 90th percentile (β = -.21, CI = -.24, - .18) was significantly larger than among either lighter drinkers at the 50th percentile (β = - .02, CI = -.02, -.01) or heavier drinkers at the 95th percentile (β = -.16, CI = -.18, -.13).
Conclusions: Alcohol consumption among young people in England appears to be declining across the consumption distribution, and peaks among heavy drinkers. The magnitude of this decline differs significantly between percentiles of the consumption distribution, with consumption falling proportionally less among the lightest, moderate and very heaviest youth drinkers
The amyloid β peptide Aβ (25–35) induces apoptosis independent of p53
AbstractApoptosis of neuronal cells apparently plays a role in Alzheimer’s disease (AD). The amyloid beta (Aβ) peptide derived from β-amyloid precursor protein is found in AD brain in vivo and can induce apoptosis in vitro. While p53 accumulates in cells of AD brain, it is not known if p53 plays an active role in Aβ-induced apoptosis. We show here that inactivation of p53 in two experimental cell lines, either by expression of the papillomavirus E6 protein or by a shift to restrictive temperature, does not affect apoptosis induction by Aβ (25–35), indicating that Aβ induces apoptosis in a p53-independent manner
Conservative and disruptive modes of adolescent change in human brain functional connectivity
Adolescent changes in human brain function are not entirely understood. Here, we used multiecho functional MRI (fMRI) to measure developmental change in functional connectivity (FC) of resting-state oscillations between pairs of 330 cortical regions and 16 subcortical regions in 298 healthy adolescents scanned 520 times. Participants were aged 14 to 26 y and were scanned on 1 to 3 occasions at least 6 mo apart. We found 2 distinct modes of age-related change in FC: “conservative” and “disruptive.” Conservative development was characteristic of primary cortex, which was strongly connected at 14 y and became even more connected in the period from 14 to 26 y. Disruptive development was characteristic of association cortex and subcortical regions, where connectivity was remodeled: connections that were weak at 14 y became stronger during adolescence, and connections that were strong at 14 y became weaker. These modes of development were quantified using the maturational index (MI), estimated as Spearman’s correlation between edgewise baseline FC (at 14 y, FC14) and adolescent change in FC (ΔFC14−26), at each region. Disruptive systems (with negative MI) were activated by social cognition and autobiographical memory tasks in prior fMRI data and significantly colocated with prior maps of aerobic glycolysis (AG), AG-related gene expression, postnatal cortical surface expansion, and adolescent shrinkage of cortical thickness. The presence of these 2 modes of development was robust to numerous sensitivity analyses. We conclude that human brain organization is disrupted during adolescence by remodeling of FC between association cortical and subcortical areas
Reality in quantum mechanics, Extended Everett Concept, and consciousness
Conceptual problems in quantum mechanics result from the specific quantum
concept of reality and require, for their solution, including the observer's
consciousness into quantum theory of measurements. Most naturally this is
achieved in the framework of Everett's "many-worlds interpretation" of quantum
mechanics. According to this interpretation, various classical alternatives are
perceived by consciousness separately from each other. In the Extended Everett
Concept (EEC) proposed by the present author, the separation of the
alternatives is identified with the phenomenon of consciousness. This explains
classical character of the alternatives and unusual manifestations of
consciousness arising "at the edge of consciousness" (i.e. in sleep or trance)
when its access to "other alternative classical realities" (other Everett's
worlds) becomes feasible. Because of reversibility of quantum evolution in EEC,
all time moments in the quantum world are equivalent while the impression of
flow of time appears only in consciousness. If it is assumed that consciousness
may influence onto probabilities of alternatives (which is consistent in case
of infinitely many Everett's worlds), EEC explains free will, "probabilistic
miracles" (observing low-probability events) and decreasing entropy in the
sphere of life.Comment: 17 pages, 2 figures in EP
Hydrodynamic dispersion within porous biofilms
Many microorganisms live within surface-associated consortia, termed biofilms, that can form intricate porous structures interspersed with a network of fluid channels. In such systems, transport phenomena, including flow and advection, regulate various aspects of cell behavior by controlling nutrient supply, evacuation of waste products, and permeation of antimicrobial agents. This study presents multiscale analysis of solute transport in these porous biofilms. We start our analysis with a channel-scale description of mass transport and use the method of volume averaging to derive a set of homogenized equations at the biofilm-scale in the case where the width of the channels is significantly smaller than the thickness of the biofilm. We show that solute transport may be described via two coupled partial differential equations or telegrapher's equations for the averaged concentrations. These models are particularly relevant for chemicals, such as some antimicrobial agents, that penetrate cell clusters very slowly. In most cases, especially for nutrients, solute penetration is faster, and transport can be described via an advection-dispersion equation. In this simpler case, the effective diffusion is characterized by a second-order tensor whose components depend on (1) the topology of the channels' network; (2) the solute's diffusion coefficients in the fluid and the cell clusters; (3) hydrodynamic dispersion effects; and (4) an additional dispersion term intrinsic to the two-phase configuration. Although solute transport in biofilms is commonly thought to be diffusion dominated, this analysis shows that hydrodynamic dispersion effects may significantly contribute to transport
Distinct fos-expressing neuronal ensembles in the ventromedial prefrontal cortex mediate food reward and extinction memories
In operant learning, initial reward-associated memories are thought to be distinct from subsequent extinction-associated memories.
Memories formed during operant learning are thought to be stored in “neuronal ensembles.” Thus, we hypothesize that different
neuronal ensembles encode reward- and extinction-associated memories. Here, we examined prefrontal cortex neuronal ensembles
involved in the recall of reward and extinction memories of food self-administration.Wefirst trained rats to lever press for palatable food
pellets for 7 d (1 h/d) and then exposed them to 0, 2, or 7 daily extinction sessions in which lever presses were not reinforced. Twenty-four
hours after the last training or extinction session, we exposed the rats to either a short 15 min extinction test session or left them in their
homecage (a control condition). We found maximal Fos (a neuronal activity marker) immunoreactivity in the ventral medial prefrontal
cortex of rats that previously received 2 extinction sessions, suggesting that neuronal ensembles in this area encode extinction memories.
We then used the Daun02 inactivation procedure to selectively disrupt ventral medial prefrontal cortex neuronal ensembles that were
activated during the 15 min extinction session following 0 (no extinction) or 2 prior extinction sessions to determine the effects of
inactivating the putative food reward and extinction ensembles, respectively, on subsequent nonreinforced food seeking 2 d later.
Inactivation of the food reward ensembles decreased food seeking, whereas inactivation of the extinction ensembles increased food
seeking. Our results indicate that distinct neuronal ensembles encoding operant reward and extinction memories intermingle within the
same cortical area
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