Observations of pressure anisotropy effects within semi-collisional magnetized plasma bubbles.

Magnetized plasma interactions are ubiquitous in astrophysical and laboratory plasmas. Various physical effects have been shown to be important within colliding plasma flows influenced by opposing magnetic fields, however, experimental verification of the mechanisms within the interaction region has remained elusive. Here we discuss a laser-plasma experiment whereby experimental results verify that Biermann battery generated magnetic fields are advected by Nernst flows and anisotropic pressure effects dominate these flows in a reconnection region. These fields are mapped using time-resolved proton probing in multiple directions. Various experimental, modelling and analytical techniques demonstrate the importance of anisotropic pressure in semi-collisional, high-ß plasmas, causing a reduction in the magnitude of the reconnecting fields when compared to resistive processes. Anisotropic pressure dynamics are crucial in collisionless plasmas, but are often neglected in collisional plasmas. We show pressure anisotropy to be essential in maintaining the interaction layer, redistributing magnetic fields even for semi-collisional, high energy density physics (HEDP) regimes.

A spectrometer for ultrashort gamma-ray pulses with photon energies greater than 10 MeV.

We present a design for a pixelated scintillator based gamma-ray spectrometer for non-linear inverse Compton scattering experiments. By colliding a laser wakefield accelerated electron beam with a tightly focused, intense laser pulse, gamma-ray photons up to 100 MeV energies and with few femtosecond duration may be produced. To measure the energy spectrum and angular distribution, a 33 × 47 array of cesium-iodide crystals was oriented such that the 47 crystal length axis was parallel to the gamma-ray beam and the 33 crystal length axis was oriented in the vertical direction. Using an iterative deconvolution method similar to the YOGI code, modeling of the scintillator response using GEANT4 and fitting to a quantum Monte Carlo calculated photon spectrum, we are able to extract the gamma ray spectra generated by the inverse Compton interaction.

Kinetic modeling of Nernst effect in magnetized hohlraums.

We present nanosecond time-scale Vlasov-Fokker-Planck-Maxwell modeling of magnetized plasma transport and dynamics in a hohlraum with an applied external magnetic field, under conditions similar to recent experiments. Self-consistent modeling of the kinetic electron momentum equation allows for a complete treatment of the heat flow equation and Ohm's law, including Nernst advection of magnetic fields. In addition to showing the prevalence of nonlocal behavior, we demonstrate that effects such as anomalous heat flow are induced by inverse bremsstrahlung heating. We show magnetic field amplification up to a factor of 3 from Nernst compression into the hohlraum wall. The magnetic field is also expelled towards the hohlraum axis due to Nernst advection faster than frozen-in flux would suggest. Nonlocality contributes to the heat flow towards the hohlraum axis and results in an augmented Nernst advection mechanism that is included self-consistently through kinetic modeling.

Magnetic reconnection in plasma under inertial confinement fusion conditions driven by heat flux effects in Ohm's law.

In the interaction of high-power laser beams with solid density plasma there are a number of mechanisms that generate strong magnetic fields. Such fields subsequently inhibit or redirect electron flows, but can themselves be advected by heat fluxes, resulting in complex interplay between thermal transport and magnetic fields. We show that for heating by multiple laser spots reconnection of magnetic field lines can occur, mediated by these heat fluxes, using a fully implicit 2D Vlasov-Fokker-Planck code. Under such conditions, the reconnection rate is dictated by heat flows rather than Alfvènic flows. We find that this mechanism is only relevant in a high ß plasma. However, the Hall parameter ωcτei can be large so that thermal transport is strongly modified by these magnetic fields, which can impact longer time scale temperature homogeneity and ion dynamics in the system.

Stressful life-events, anxiety, depression and coping in patients of irritable bowel syndrome.

UNLABELLED: A lot of research has pointed to a complex interaction between stressful life events, psychiatric morbidity and the irritable bowel syndrome (IBS). AIM: The present study aimed to determine the: stressful life-events in patients with irritable bowel syndrome patients in comparison to normal controls; effect of these events in causing clinically significant anxiety and depression; and the effect of psychopathology i.e. anxiety and depression on coping skills in these patients. METHODOLOGY: Thirty patients with irritable bowel syndrome were compared with thirty matched normal controls, on the presumptive stressful life events scale and the mechanisms of coping scale. Further, among the irritable bowel syndrome patient group, the anxious and depressed subgroups were separated from the non-anxious and non-depressed subgroups using the hospital anxiety and depression scale. Positive and negative coping mechanisms between these subgroups were compared. RESULTS: Significantly higher stress scores were found in the irritable bowel syndrome patient group than normal controls. Not all, but slightly more than fifty percent of irritable bowel syndrome had definite and clinically significant anxiety and/or depression. Those IBS patients with either definite depression tended to use predominantly negative coping styles as compared to those IBS patients without anxiety or depression. CONCLUSION: Stressful life-event scores are significantly higher in IBS patients than in normal controls. Although not all of these patients have anxiety and/or depression, a significant number of patients show evidence of the same. Presence or absence of anxiety and/or depression influences how the patient with IBS copes with illness. Therefore, though further studies on the issue are required, we suggested that, as a supplement to medical management, recognition and treatment of anxiety and depression in this subgroup of IBS patients with psychotropic drugs and cognitive therapy for gaining more positive coping skills, may require special attention in the management of irritable bowel syndrome.

Poor insight in schizophrenia: neurocognitive basis.

Poor insight in schizophrenia has been recently thought to be a reflection of prominent and enduring neurocognitive impairments. Reports supporting this theory have implicated prefrontal and parietal lobe functions, among other parameters. The results of other studies have negated the role of neuropsychological abnormalities in poor insight. The analogy between poor insight in schizophrenia and anosognosia in neurological illness as proposed by one set of workers has been elucidated in this review and it appears quite promising. However, the drawing of definite conclusions from all this work has been deferred by us, because of the need for more uniform and standardized methodologies for research on the subject. Nevertheless, attempts to improve the cognitive processes, which affect insight in schizophrenia, may be done to gain better treatment outcome in this disorder.

Munchausen's syndrome.

Munchausen's syndrome is a chronic condition in which patients with factitious illness present with dramatic and sometimes self-inflicted signs and symptoms. Much investigation is needed to delineate the etiology and psychodynamics of this disorder. After other causes for the patient's condition have been ruled out and a firm diagnosis is made, cautious confrontation with long-term psychotherapy, if the patient is amenable, is thought to be the best approach.