16,011 research outputs found
NATURAL HISTORY AND MERISTICS OF AN ALLOPATRIC POPULATION OF RED CORNSNAKES, PANTHEROPHIS GUTTATUS (LINNAEUS, 1766) IN CENTRAL KENTUCKY, USA
Life history, morphological variation, and basic biology of Pantherophis guttatus (Linnaeus, 1766), the Red Cornsnake, are not well known, particularly for the allopatric populations in Kentucky. To address some of the information gaps for this species, we report field observations, including activity patterns, reproduction, and meristics of P. guttatus in Kentucky. In 2003 and 2004 we conducted field surveys using drift fences, artificial cover, manual searching, and driving on roads and captured 101 P. guttatus in Edmonson and Hart counties, Kentucky. We found that artificial cover was the best method of detection with 77% of snakes captured using this method. Numbers of encounters peaked in April-May and August-September suggesting bimodal activity patterns similar to other colubrid snakes. Males had signifi cantly higher subcaudal scale counts than females while females had significantly higher ventral scale counts than males. We detected more individuals in 2003 than in 2004, most likely influenced by severe drought conditions in Kentucky during 2004. Size-class distribution of snakes was skewed towards large individuals (> 70 cm SVL). The absence of individuals in juvenile size classes (30 cm -70 cm) may be an artifact of lower detection probabilities for smaller size classes, different habitat use by juveniles, or may indicate low recruitment
The XMM Newton and INTEGRAL observations of the supergiant fast X-ray transient IGR J16328-4726
The accretion mechanism producing the short flares observed from the
Supergiant Fast X-ray Transients (SFXT) is still highly debated and forms a
major part in our attempts to place these X-ray binaries in the wider context
of the High Mass X-ray Binaries.
We report on a 216 ks INTEGRAL observation of the SFXT IGR J16328-4726
(August 24-27, 2014) simultaneous with two fixed-time observations with XMM
Newton (33ks and 20ks) performed around the putative periastron passage, in
order to investigate the accretion regime and the wind properties during this
orbital phase. During these observations, the source has shown luminosity
variations, from 4x10^{34} erg/s to 10^{36} erg/s, linked to spectral
properties changes. The soft X-ray continuum is well modeled by a power law
with a photon index varying from 1.2 up to 1.7 and with high values of the
column density in the range 2-4x10^{23}/cm^2. We report on the presence of iron
lines at 6.8-7.1 keV suggesting that the X-ray flux is produced by accretion of
matter from the companion wind characterized by density and temperature
inhomogeneities
Consolidation of complex events via reinstatement in posterior cingulate cortex
It is well-established that active rehearsal increases the efficacy of memory consolidation. It is also known that complex events are interpreted with reference to prior knowledge. However, comparatively little attention has been given to the neural underpinnings of these effects. In healthy adult humans, we investigated the impact of effortful, active rehearsal on memory for events by showing people several short video clips and then asking them to recall these clips, either aloud (Experiment 1) or silently while in an MRI scanner (Experiment 2). In both experiments, actively rehearsed clips were remembered in far greater detail than unrehearsed clips when tested a week later. In Experiment 1, highly similar descriptions of events were produced across retrieval trials, suggesting a degree of semanticization of the memories had taken place. In Experiment 2, spatial patterns of BOLD signal in medial temporal and posterior midline regions were correlated when encoding and rehearsing the same video. Moreover, the strength of this correlation in the posterior cingulate predicted the amount of information subsequently recalled. This is likely to reflect a strengthening of the representation of the video's content. We argue that these representations combine both new episodic information and stored semantic knowledge (or "schemas"). We therefore suggest that posterior midline structures aid consolidation by reinstating and strengthening the associations between episodic details and more generic schematic information. This leads to the creation of coherent memory representations of lifelike, complex events that are resistant to forgetting, but somewhat inflexible and semantic-like in nature
Thermodiffusion in model nanofluids by molecular dynamics simulations
In this work, a new algorithm is proposed to compute single particle
(infinite dilution) thermodiffusion using Non-Equilibrium Molecular Dynamics
simulations through the estimation of the thermophoretic force that applies on
a solute particle. This scheme is shown to provide consistent results for
simple Lennard-Jones fluids and for model nanofluids (spherical non-metallic
nanoparticles + Lennard-Jones fluid) where it appears that thermodiffusion
amplitude, as well as thermal conductivity, decrease with nanoparticles
concentration. Then, in nanofluids in the liquid state, by changing the nature
of the nanoparticle (size, mass and internal stiffness) and of the solvent
(quality and viscosity) various trends are exhibited. In all cases the single
particle thermodiffusion is positive, i.e. the nanoparticle tends to migrate
toward the cold area. The single particle thermal diffusion 2 coefficient is
shown to be independent of the size of the nanoparticle (diameter of 0.8 to 4
nm), whereas it increases with the quality of the solvent and is inversely
proportional to the viscosity of the fluid. In addition, this coefficient is
shown to be independent of the mass of the nanoparticle and to increase with
the stiffness of the nanoparticle internal bonds. Besides, for these
configurations, the mass diffusion coefficient behavior appears to be
consistent with a Stokes-Einstein like law
Executive processes in Asperger syndrome: Patterns of performance in a multiple case series
Mixed evidence exists for executive dysfunction in autism spectrum disorders (ASD). This may be because of the nature of the tasks used, the heterogeneity of participants, and difficulties with recruiting appropriate control groups. A comprehensive battery of ‘executive’ tests was administered to 22 individuals with Asperger syndrome and 22 well-matched controls. Performance was analysed both between groups and on an individual basis to identify outliers in both the ASD and control groups. There were no differences between the groups on all ‘classical’ tests of executive function. However, differences were found on newer tests of executive function. Specifically, deficits in planning, abstract problem solving and especially multitasking. On the tests that discriminated the groups, all of the ASD individuals except one were identified as significantly impaired (i.e. below the 5th percentile of the control mean) on at least one executive measure. This study provides evidence for significant executive dysfunction in Asperger syndrome. Greatest dysfunction appeared in response initiation and intentionality at the highest level—the ability to engage and disengage actions in the service of overarching goals. These deficits are best observed through using more recent, ecologically valid tests of executive dysfunction. Moreover, performance on these measures correlated with autistic symptomatology
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