Kinetic simulations of X-B and O-X-B mode conversion

We have performed fully-kinetic simulations of X-B and O-X-B mode conversion in one and two dimensional setups using the PIC code EPOCH. We have recovered the linear dispersion relation for electron Bernstein waves by employing relatively low amplitude incoming waves. The setups presented here can be used to study non-linear regimes of X-B and O-X-B mode conversion.Comment: 4 pages, 3 figure

WAT-A-GAME: sharing water and policies in your own basin

40th Annual Conference, Int. Simulation And Gaming Association, Singapour, SGP, 29-/06/2009 - 03/07/2009International audienceAfter having designed and used various games for learning and supporting water management and governance, many similarities appear. However, the components, topologies, and social and political setting of the basins are different. Therefore we have started designing andvalidating a new generic game platform, WAT-A-GAME, alias AMANZI. This new game aims at facilitating exploration and transformation of water management and water use at the small catchment scale. It gives a simple but enlightening view of the various consequences of individual and collective choices, including regulation policies. After comparing it with some previous games, we discuss its main rationales and features. We show how it can be adapted to very different settings, how players can usefully contribute to designing an instance, and how it can especially address dialogue between multi-level stakeholders. We describe an application in South-Africa, in the Inkomati basin and the preliminary results of this instance

Time-randomized stopping problems for a family of utility functions

This paper studies stopping problems of the form $V=\inf_{0 \leq \tau \leq T} \mathbb{E}[U(\frac{\max_{0\le s \le T} Z_s }{Z_\tau})]$ for strictly concave or convex utility functions U in a family of increasing functions satisfying certain conditions, where Z is a geometric Brownian motion and T is the time of the nth jump of a Poisson process independent of Z. We obtain some properties of $V$ and offer solutions for the optimal strategies to follow. This provides us with a technique to build numerical approximations of stopping boundaries for the fixed terminal time optimal stopping problem presented in [J. Du Toit and G. Peskir, Ann. Appl. Probab., 19 (2009), pp. 983--1014]

SWIRP (Submm-Wave and Long Wave InfraRed Polarimeter); Development and Characterization of a Sub-Mm Polarimeter for Ice Cloud Investigations

A major source of uncertainty in climate models is the presence, shape and distribution of ice particles in the uppermost layers of the clouds. The effects of this component are poorly constrained, turning ice particles into an almost-free variable in many climate models.NASA-GSFC is developing a new instrument aimed at measuring the size and shape of ice particles. The instrument consists of two sub-mm polarimeters (at 220 and 670 GHz) coupled with a long-wave infrared polarimeter at 10 micron. Each polarimeter has identical V-pol and H-pol channels; the axes of polarization are defined geometrically by the orientation of the waveguide elements, and the purity has been measured in the lab. The instrument is configured as a conical scanner, suitable for deployment as a payload on a small satellite or on a high-altitude sub-orbital platform. From a 400 km orbit, the instrument has a 3dB spatial resolution of 20 (10) km at 220 (670) GHz and a swath of 600 km over 180 degrees of view.The BAPTA (Bearing And Power Transfer Assembly) carries heritage from the SSMIS design, now in its 22nd year of on-orbit operation, but with a much reduced SWaP (Size Weight and Power) footprint, suitable for a small satellite.The main components of the instrument have been fabricated and are undergoing final testing prior to their integration as a single unit. The sub-mm channels have dedicated secondary reflectors which illuminate a shared primary reflector. The receiving units are placed behind the focal point of the optical arrangement, so that all beams equally illuminate the primary reflector and are almost co-located on the ground (within a single 220 GHz footprint). Primary and secondary beam patterns have been measured and verified to match the as-designed expectations. A Zytex (TM) window is deployed to protect the secondary reflectors and the feed horns from debris and other contaminants, and to reduce the heat load from the active (hot) IR calibration unit. The insertion loss of Zytex has been measured and is accounted in the calibration equation of the sub-mm channels.The radiometric performance of the sub-mm receivers has been characterized in the lab and under operational conditions of temperature and pressure.This paper discusses the design constraints on the sub-mm components, details of the scientific goals and their flowdown, and describes the characterization of the polarimeters. Options to optimize the layout and distribution of the masses within the assembly, with the goal of making the instrument even more compact and fully-compatible with cubesat-class satellites will be presented

Obsessive-compulsive disorder and trichotillomania: a phenomenological comparison

RIGHTS : This article is licensed under the BioMed Central licence at http://www.biomedcentral.com/about/license which is similar to the 'Creative Commons Attribution Licence'. In brief you may : copy, distribute, and display the work; make derivative works; or make commercial use of the work - under the following conditions: the original author must be given credit; for any reuse or distribution, it must be made clear to others what the license terms of this work are.Abstract Background Similarities between obsessive-compulsive disorder (OCD) and trichotillomania (TTM) have been widely recognized. Nevertheless, there is evidence of important differences between these two disorders. Some authors have conceptualized the disorders as lying on an OCD spectrum of conditions. Methods Two hundred and seventy eight OCD patients (n = 278: 148 male; 130 female) and 54 TTM patients (n = 54; 5 male; 49 female) of all ages were interviewed. Female patients were compared on select demographic and clinical variables, including comorbid axis I and II disorders, and temperament/character profiles. Results OCD patients reported significantly more lifetime disability, but fewer TTM patients reported response to treatment. OCD patients reported higher comorbidity, more harm avoidance and less novelty seeking, more maladaptive beliefs, and more sexual abuse. OCD and TTM symptoms were equally likely to worsen during menstruation, but OCD onset or worsening was more likely associated with pregnancy/puerperium. Conclusions These findings support previous work demonstrating significant differences between OCD and TTM. The classification of TTM as an impulse control disorder is also problematic, and TTM may have more in common with conditions characterized by stereotypical self-injurious symptoms, such as skin-picking. Differences between OCD and TTM may reflect differences in underlying psychobiology, and may necessitate contrasting treatment approaches.Published versio

Die strafregtelike aanspreeklikheid van regspersone: Lesse uit Kanada

This contribution investigates the basis for the criminal liability of juristic persons in Canada in an attempt to gain lessons for South Africa. The Canadian position acknowledges both the fragmented nature of corporate decision-making and the reality that the collective efforts of a number of corporate role players may cause criminal conduct. Furthermore, the conduct and fault elements of corporate criminal misconduct do not have to be found in one individual. The conduct of a representative of the corporate entity may be regarded as the conduct of the corporation, whilst the fault requirement may be found to be the level of management. This approach, although not entirely ‘realistic’, takes into account the nature of modern corporate entities much better than traditional individualistic approaches to corporate criminal liability

Onderwysersopleiding*

In die geskiedenis kom die verskynsel telkens voor dat besondere aandag aan die onderwys geskenk word in krisistye wanneer materiële teëslae ondervind word of wanneer ’n lewensbeskouing wat lank gehuldig is, teleurstel. Dit is dan ook begryplik dat die onderwys in die huidige tydstip van die dreigende verval van Westerse gesag deur toonaangewende lande aan indringende ondersoek onderwerp word. Bloot as verteenwoordiger van die Westerse beskawing in Afrika sou die Republiek van Suid-Afrika dus al dringende aandag aan die vraagstuk moes skenk van hoe die onderwys en opvoeding ten voordeligste aangewend kan word om die toenemende verval te help stuit en ’n nuwe periode van vooruitgang en beskawingsgroei teweeg te probeer bring. Maar die blanke volk hier te lande verkeer nog in ’n veel eiesoortiger en kwesbaarder posisie as die meeste Westerse nasies van wie hy afstam. Die feit bly staan dat ons ons vorm van beskawing nog nie onomkeerbaar in hierdie land gevestig het nie. Meer as enige land van Europa of die Nuwe Wêreld staan ons in gevaar van oorrompeling deur barbarisme wat van buite dreig. Om die rede kan ons miskien minder as enige ander land bekostig dat daar interne onsekerheid is oor wat ons as enkelinge en as volk nastreef, want dit kan in sy konsekwensie slegs tot twyfel en gebrek aan eenheid lei. As ons hierby voeg die noodsaaklikheid om binne dekades oor te skakel na ’n nog gekompliseerder nywerheidsamelewing, om ’n nuwe en menswaardige bedeling uit te bou vir die saambestaan van rasse van Europese, inheemse en Asiatiese oorsprong, elk met sy eie kulturele en tradisionele agtergrond, en om die volgehoue en toenemende internasionale druk op ons beleid die hoof te bied, dan is die omvang wat die onderwystaak in hierdie land aanneem duiselingwekkend

Revival of the magnetar PSR J1622-4950: observations with MeerKAT, Parkes, XMM-Newton, Swift, Chandra, and NuSTAR

New radio (MeerKAT and Parkes) and X-ray (XMM-Newton, Swift, Chandra, and NuSTAR) observations of PSR J1622-4950 indicate that the magnetar, in a quiescent state since at least early 2015, reactivated between 2017 March 19 and April 5. The radio flux density, while variable, is approximately 100x larger than during its dormant state. The X-ray flux one month after reactivation was at least 800x larger than during quiescence, and has been decaying exponentially on a 111+/-19 day timescale. This high-flux state, together with a radio-derived rotational ephemeris, enabled for the first time the detection of X-ray pulsations for this magnetar. At 5%, the 0.3-6 keV pulsed fraction is comparable to the smallest observed for magnetars. The overall pulsar geometry inferred from polarized radio emission appears to be broadly consistent with that determined 6-8 years earlier. However, rotating vector model fits suggest that we are now seeing radio emission from a different location in the magnetosphere than previously. This indicates a novel way in which radio emission from magnetars can differ from that of ordinary pulsars. The torque on the neutron star is varying rapidly and unsteadily, as is common for magnetars following outburst, having changed by a factor of 7 within six months of reactivation.Comment: Published in ApJ (2018 April 5); 13 pages, 4 figure