467 research outputs found
Fuzzy cellular model for on-line traffic simulation
This paper introduces a fuzzy cellular model of road traffic that was
intended for on-line applications in traffic control. The presented model uses
fuzzy sets theory to deal with uncertainty of both input data and simulation
results. Vehicles are modelled individually, thus various classes of them can
be taken into consideration. In the proposed approach, all parameters of
vehicles are described by means of fuzzy numbers. The model was implemented in
a simulation of vehicles queue discharge process. Changes of the queue length
were analysed in this experiment and compared to the results of NaSch cellular
automata model.Comment: The original publication is available at http://www.springerlink.co
Rx3 and Shh direct anisotropic growth and specification in the zebrafish tuberal/anterior hypothalamus.
In the developing brain, growth and differentiation are intimately linked. Here we show that in the zebrafish embryo, the homeodomain transcription factor rx3 co-ordinates these processes to build the tuberal/anterior hypothalamus. Analysis of rx3 chk mutant/rx3 morphant fish and EdU pulse-chase studies reveal that rx3 is required to select tuberal/anterior hypothalamic progenitors and to orchestrate their anisotropic growth. In the absence of rx3 function, progenitors accumulate in the 3(rd) ventricular wall, die or are inappropriately-specified, the shh+ anterior recess does not form, and its resident pomc+, ff1b+ and otp+ TH+ cells fail to differentiate. Manipulation of Shh signalling shows that shh co-ordinates progenitor cell selection and behaviour by acting as an on-off switch for rx3 Together our studies show that shh and rx3 govern formation of a distinct progenitor domain that elaborates pattern through its anisotropic growth and differentiation
Disrupted-in-schizophrenia-1 is essential for normal hypothalamic-pituitary-interrenal (HPI) axis function
Psychiatric disorders arise due to an interplay of genetic and environmental factors, including stress. Studies in rodents have
shown that mutants for Disrupted-In-Schizophrenia-1 (DISC1), a well-accepted genetic risk factor for mental illness, display
abnormal behaviours in response to stress, but the mechanisms through which DISC1 affects stress responses remain poorly
understood. Using two lines of zebrafish homozygous mutant for disc1, we investigated behaviour and functioning of the
hypothalamic-pituitary-interrenal (HPI) axis, the fish equivalent of the hypothalamic-pituitary-adrenal (HPA) axis. Here, we
show that the role of DISC1 in stress responses is evolutionarily conserved and that DISC1 is essential for normal functioning
of the HPI axis. Adult zebrafish homozygous mutant for disc1 show aberrant behavioural responses to stress. Our studies
reveal that in the embryo, disc1 is expressed in neural progenitor cells of the hypothalamus, a conserved region of the vertebrate
brain that centrally controls responses to environmental stressors. In disc1 mutant embryos, proliferating rx3þ hypothalamic
progenitors are not maintained normally and neuronal differentiation is compromised: rx3-derived ff1bþ neurons,
implicated in anxiety-related behaviours, and corticotrophin releasing hormone (crh) neurons, key regulators of the stress axis,
develop abnormally, and rx3-derived pomcþ neurons are disorganised. Abnormal hypothalamic development is associated
with dysfunctional behavioural and neuroendocrine stress responses. In contrast to wild type siblings, disc1 mutant larvae
show altered crh levels, fail to upregulate cortisol levels when under stress and do not modulate shoal cohesion, indicative of
abnormal social behaviour. These data indicate that disc1 is essential for normal development of the hypothalamus and for
the correct functioning of the HPA/HPI axis
Zebrafish as a model to investigate the CRH axis and interactions with DISC1
Release of corticotropin-releasing hormone (CRH) from CRH neurons activates the hypothalamo–pituitary–adrenal (HPA) axis, one of the main physiological stress response systems. Complex feedback loops operate in the HPA axis and understanding the neurobiological mechanisms regulating CRH neurons is of great importance in the context of stress disorders. In this article, we review how in vivo studies in zebrafish have advanced knowledge of the neurobiology of CRH neurons. Disrupted-in-schizophrenia 1 (DISC1) mutant zebrafish have blunted stress responses and can be used to model human stress disorders. We propose that DISC1 influences the development and functioning of CRH neurons as a mechanism linking DISC1 to psychiatric disorders
First-order Raman spectra of double perovskites AB''{1/2}O3
First principles computations of Raman intensities were performed for
perovskite-family compound CaAlNbO (CAN). This compound
features 1:1 (NaCl-type) ordering of Al and Nb superimposed onto the
octahedral tilting. Raman tensor for CAN was computed using the package for
first-principles computations ABINIT (URL \underline {http://www.abinit.org}).
Computations performed for both untilted cubic () and tilted
monoclinic () CAN structures showed that the strongest Raman lines are
associated with the ordering of Al and Nb. The computed spectrum agreed
qualitatively with the experimental data measured on powder (CAN is available
in polycrystalline form only). The effect of cation disorder on the Raman
intensities was considered using phenomenological theory of light scattering in
the vicinity of a phase transition. We suggest that, for certain modes, the
corresponding Raman intensities depend primarily on the average long range
order while, for other modes, the intensities are determined by fluctuations of
the order parameter.Comment: 4 figures, submitte
Higher-order QED corrections to W-boson mass determination at hadron colliders
The impact of higher-order final-state photonic corrections on the precise
determination of the W-boson mass at the Tevatron and LHC colliders is
evaluated. In the presence of realistic selection criteria, the shift in the W
mass from a fit to the transverse mass distribution is found to be about 10 MeV
in the channel and almost negligible in the
channel. The calculation, which is implemented in a Monte Carlo event generator
for data analysis, can contribute to reduce the uncertainty associated to the W
mass measurement at future hadron collider experiments.Comment: 9 pages, 2 figures, 1 table, RevTe
Peak positions and shapes in neutron pair correlation functions from powders of highly anisotropic crystals
The effect of the powder average on the peak shapes and positions in neutron
pair distribution functions of polycrystalline materials is examined. It is
shown that for highly anisotropic crystals, the powder average leads to shifts
in peak positions and to non-Gaussian peak shapes. The peak shifts can be as
large as several percent of the lattice spacing
Mechanisms Associated with Clinical Improvement in Interventions That Address Health-Related Social Needs: A Mixed-Methods Analysis
Linking individuals to community resources in order to help meet health-related social needs, such as food, medications, or transportation, may improve clinical outcomes. However, little is known about the mechanisms whereby such linkage interventions might improve health. The authors conducted a mixed-methods analysis consisting of outcomes from a prospective cohort study of a linkage intervention and a qualitative analysis of case records from participants. The cohort study included intervention participants who first enrolled between December 2014 and March 2015. Participants were excluded if they could not complete the assessment because of illness or language. The authors examined changes in cost-related medication underuse (CRMU), transportation barriers, and food insecurity (FI). For the qualitative analysis, a random sample of 80 participants was selected for electronic health record review - 40 cases who showed clinical improvement (responders) and 40 cases who did not (nonresponders). Themes were extracted by 3 reviewers guided by the immersion/crystallization approach. For the cohort study, 141 individuals were included 138 (97.9%) completed follow-up. Comparing baseline to follow-up, there were significant reductions in the prevalence of CRMU (from 44.2% to 39.1%, P = .003) and transportation barriers (from 46.3% to 30.2%, P = .001), but not FI (from 40.4% to 38.2%, P = .73). For the qualitative study, emergent themes that helped differentiate responders and nonresponders included acuity of need, resource availability/access, and adequacy of the resource utilized. CRMU and transportation barriers may be important mechanisms by which linkage interventions improve health-related social needs. Patient-centered themes can help guide intervention improvements
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