3,332 research outputs found
Modeling the effect of anisotropic pressure on tokamak plasmas normal modes and continuum using fluid approaches
Extending the ideal MHD stability code MISHKA, a new code, MISHKA-A, is
developed to study the impact of pressure anisotropy on plasma stability. Based
on full anisotropic equilibrium and geometry, the code can provide normal mode
analysis with three fluid closure models: the single adiabatic model (SA), the
double adiabatic model (CGL) and the incompressible model. A study on the
plasma continuous spectrum shows that in low beta, large aspect ratio plasma,
the main impact of anisotropy lies in the modification of the BAE gap and the
sound frequency, if the q profile is conserved. The SA model preserves the BAE
gap structure as ideal MHD, while in CGL the lowest frequency branch does not
touch zero frequency at the resonant flux surface where , inducing a
gap at very low frequency. Also, the BAE gap frequency with bi-Maxwellian
distribution in both model becomes higher if with a q
profile dependency. As a benchmark of the code, we study the m/n=1/1 internal
kink mode. Numerical calculation of the marginal stability boundary with
bi-Maxwellian distribution shows a good agreement with the generalized
incompressible Bussac criterion [A. B. Mikhailovskii, Sov. J. Plasma Phys 9,
190 (1983)]: the mode is stabilized(destabilized) if
Discovery of extreme asymmetry in the debris disk surrounding HD 15115
We report the first scattered light detection of a dusty debris disk
surrounding the F2V star HD 15115 using the Hubble Space Telescope in the
optical, and Keck adaptive optics in the near-infrared. The most remarkable
property of the HD 15115 disk relative to other debris disks is its extreme
length asymmetry. The east side of the disk is detected to ~315 AU radius,
whereas the west side of the disk has radius >550 AU. We find a blue optical to
near-infrared scattered light color relative to the star that indicates grain
scattering properties similar to the AU Mic debris disk. The existence of a
large debris disk surrounding HD 15115 adds further evidence for membership in
the Beta Pic moving group, which was previously argued based on kinematics
alone. Here we hypothesize that the extreme disk asymmetry is due to dynamical
perturbations from HIP 12545, an M star 0.5 degrees (0.38 pc) east of HD 15115
that shares a common proper motion vector, heliocentric distance, galactic
space velocity, and age.Comment: 4 pages, 3 figures, ApJ Letters, accepte
The Clinical Gestalts of Autism: Over 40 years of Clinical Experience with Autism
The clinical gestalts of autism are very broad and much more heterogeneous than people realise. DSM V [1] gives a more narrow and condensed description of what autism is in the twentieth century. DSM focuses on problems with socioemotional reciprocity, non-verbal communication and difficult interpersonal relationships, restricted, repetitive patterns of behaviour, early onset and functional impairment. First, I want to flesh out the autism spectrum disorder gestalts as it presents to experienced clinical practitioners. It is the opposite of the “tick box” approach to diagnosis so common today. It focuses on the phenomena as they would have been focused on in the late nineteenth and early twentieth century, an approach that has faded into the background in the late twentieth and early twenty-first century. It is critical at this point of the twenty-first century that we re-engage with phenomenology and with the clinical gestalt of psychiatric conditions which show a great deal of overlap with much mixed phenomenology. We will start by examining social relations in autism spectrum disorders. Clearly, this is central to autism
The Our Solar Siblings Pipeline: Tackling the data issues of the scaling problem for robotic telescope based astronomy education projects
In this paper, a pipeline designed to produce data products for education is described. The primary goal of the pipeline is to facilitate teacher usage of robotic telescopes in the classroom and to reduce administration time for project personnel. In so doing, it produces data products that are scientifically valid and robust using multiple different photometric measurement techniques to create catalogues of both instrumental measurements as well as calibrated measurements crossmatched to popular astronomical catalogues where standard stars are available. The main blocking factors that the pipeline addresses are outlined, an overview of the pipeline is provided and it’s future development is forecast
The Witness of the Monotheistic Religions
Archbishop Michael Fitzgerald is President of the Pontifical Council for Interreligious Dialogue. This talk was delivered on April 28, 2003, as the Annual Lecture hosted by the Center for Christian-Jewish Understanding of Sacred Heart University, on the eve of a conference sponsored by the CCJU titled ``Pathways to Peace in the Abrahamic Faiths.\u27\u2
Dissociation of β1 and β2 Adrenergic Receptor Subtypes in Retrieval and Reconsolidation of a Cocaine Conditioned Place Preference
Drug-seeking behavior is maintained by encounters with drug-associated cues, and disrupting retrieval or reconsolidation of the drug-cue associations could reduce the risk of relapse. Previous work has shown beta-adrenergic receptor (beta-AR) antagonists can prevent retrieval or reconsolidation of a cocaine conditioned place preference (CPP) when administered either before or after test, respectively (Otis and Mueller, 2011; Otis et al., 2013). However, the specific beta-AR subtypes that mediate retrieval and reconsolidation of a cocaine CPP remain unknown. Here we used selective blockade of & beta-1 or beta-2-AR subtypes to determine the effects on retrieval and reconsolidation of a cocaine CPP. During conditioning, rats were trained to associate one chamber, but not another, with cocaine. Memory retrieval was then tested by allowing the rats access to both chambers, resulting in a CPP for the previously cocaine-paired side. Pre-test injection of the beta-1-AR antagonist betaxolol at 20 mg/kg, i.p. but not 3 mg/kg prevented expression of a cocaine-induced CPP, indicating beta-1-AR involvement in memory retrieval. During subsequent drug-free tests, saline-treated rats continued to show a CPP, whereas betaxolol-treated rats did not. Moreover, treatment with the higher dose of betaxolol prevented subsequent reinstatement to a priming injection of cocaine. Unlike betaxolol administration, pre-test injection of the beta-2-AR antagonist ICI 118,551 (4 or 8 mg/kg, i.p.) had no affect on expression of a cocaine-induced CPP. On subsequent tests, however, vehicle- and 4 mg/kg ICI 118,551-treated rats continued to show a CPP whereas 8 mg/kg ICI 118,551-treated rats did not, indicative of a deficit in reconsolidation following this higher dose. Moreover, ICI 118,551 treatment prevented subsequent reinstatement to a priming injection of cocaine. Thus, we conclude that retrieval of a CPP is dependent on beta-1-ARs whereas reconsolidation of a CPP is dependent on beta-2-ARs. Finally, co-injection of betaxolol (20 mg/kg) and ICI 118,551 (8 mg/kg) prevented CPP expression on that and subsequent CPP tests, resulting in a long-lasting retrieval deficit that prevented reinstatement to a priming injection of cocaine. Our findings support the use of beta-AR antagonists as adjuncts for addiction therapies by preventing retrieval and reconsolidation of drug-associated memories and providing protection against relapse
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