HESS J1825-137: A pulsar wind nebula associated with PSR B1823-13?

HESS J1825-137 was detected with a significance of 8.1 $\sigma$ in the Galactic Plane survey conducted with the H.E.S.S. instrument in 2004. Both HESS J1825-137 and the X-ray pulsar wind nebula G18.0--0.7 (associated with the Vela-like pulsar PSR B1823-13) are offset south of the pulsar, which may be the result of the SNR expanding into an inhomogeneous medium. The TeV size ($\sim 35$ pc, for a distance of 4 kpc) is $\sim 6$ times larger than the X-ray size, which may be the result of propagation effects as a result of the longer lifetime of TeV emitting electrons, compared to the relatively short lifetime of keV synchrotron emitting electrons. The TeV photon spectral index of $\sim 2.4$ can also be related to the extended PWN X-ray synchrotron photon index of $\sim 2.3$, if this spectrum is dominated by synchrotron cooling. The anomalously large size of the pulsar wind nebula can be explained if the pulsar was born with a relatively large initial spindown power and braking index $n\sim 2$, provided that the SNR expanded into the hot ISM with relatively low density ($\sim 0.003$ cm$^{-3}$).Comment: 4 pages, 4 figures, to appear in the Proc. of the 29th International Cosmic Ray Conference, OG Sessio

Exploring student teachers’ experiences of vulnerability in higher education spaces

Recently, scientific interest in higher education students’ wellbeing has increased. The highlighted issues include professional development, professional identity, and personal behaviour. The significance of this study relates specifically to supporting students’ wellbeing by gaining an understanding of factors contributing to their experiences of vulnerability. Through the arts-informed methodology of Photovoice, which emerges from community-based participatory research, 16 student teachers explored the concept of vulnerability in the context of a higher education institution. The research project required student teachers to take photos of that which represents what they perceive as vulnerability. Student teachers explored their personal, school and campus space with this project. Ultimately, this research speaks to the Sustainable Development Goal of good health and wellbeing, which seeks to promote wellbeing across the individual life span, and ensure healthy lives, as well as the Sustainable Development Goal of quality education, which emphasises the need to improve quality of life and quality teacher training

Flavor decomposition of the elastic nucleon electromagnetic form factors

The u- and d-quark contributions to the elastic nucleon electromagnetic form factors have been determined using experimental data on GEn, GMn, GpE, and GpM. Such a flavor separation of the form factors became possible up to 3.4 GeV2 with recent data on GEn from Hall A at JLab. At a negative four-momentum transfer squared Q2 above 1 GeV2, for both the u- and d-quark components, the ratio of the Pauli form factor to the Dirac form factor, F2/F1, was found to be almost constant, and for each of F2 and F1 individually, the d-quark portions of both form factors drop continuously with increasing Q2.Comment: 4 pages, 3 figure

Periodic Modulations in an X-ray Flare from Sagittarius A*

We present the highly significant detection of a quasi-periodic flux modulation with a period of 22.2 min seen in the X-ray data of the Sgr A* flare of 2004 August 31. This flaring event, which lasted a total of about three hours, was detected simultaneously by EPIC on XMM-Newton and the NICMOS near-infrared camera on the HST. Given the inherent difficulty in, and the lack of readily available methods for quantifying the probability of a periodic signal detected over only several cycles in a data set where red noise can be important, we developed a general method for quantifying the likelihood that such a modulation is indeed intrinsic to the source and does not arise from background fluctuations. We here describe this Monte Carlo based method, and discuss the results obtained by its application to a other XMM-Newton data sets. Under the simplest hypothesis that we witnessed a transient event that evolved, peaked and decayed near the marginally stable orbit of the supermassive black hole, this result implies that for a mass of 3.5 x 10^{6} Msun, the central object must have an angular momentum corresponding to a spin parameter of a=0.22.Comment: 4 pages, 6 figures, submitted to ApJ

'n Ondersoek na sielkundige verwerpingsrisikofaktore by die nieroorplantingspasient

Undergoing kidney transplantation has an impact on the physical and psychological well-being of the patient. This study focuses on the psychological aspect, and in particular on the personality structure of the transplant patient. The 16-Personality Factor Questionnaire was applied to 12 successful and 12 unsuccessful renal transplant patients at H. F. Verwoerd Hospital. A significant personality difference was noted between these two groups. The patients who rejected the kidney had a low score on factors Q1, Q2, Band Toughmindedness. This implies a lower crystallised intelligence, greater conservativeness, respect of established ideas as well as a tendency to go along with the group. This information is pertinent to the selection of patients who are psychologically suited to transplantation. Psychologists can play an  important role in the selection, preparation and rehabilitation of these patients.S Afr Med J 1990: 78: 26-2

A Cosmic Ray Positron Anisotropy due to Two Middle-Aged, Nearby Pulsars?

Geminga and B0656+14 are the closest pulsars with characteristic ages in the ran ge of 100 kyr to 1 Myr. They both have spindown powers of the order 3e34 erg/s at present. The winds of these pulsars had most probably powered pulsar wind nebulae (PWNe) that broke up less than about 100 kyr after the birth of the pulsars. Assuming that leptonic particles accelerated by the pulsars were confined in th e PWNe and were released into the interstellar medium (ISM) on breakup of the PW Ne, we show that, depending on the pulsar parameters, both pulsars make a non-ne gligible contribution to the local cosmic ray (CR) positron spectrum, and they m ay be the main contributors above several GeV. The relatively small angular dist ance between Geminga and B0656+14 thus implies an anisotropy in the local CR po sitron flux at these energies. We calculate the contribution of these pulsars to the locally observed CR electr on and positron spectra depending on the pulsar birth period and the magnitude o f the local CR diffusion coefficient. We further give an estimate of the expecte d anisotropy in the local CR positron flux. Our calculations show that within the framework of our model, the local CR posit ron spectrum imposes constraints on pulsar parameters for Geminga and B0656+14, notably the pulsar period at birth, and also the local interstellar diffusion co efficient for CR leptons.Comment: accepted for publication in ApJ

The Inhomogeneous Wind of the LBV Candidate CygOB2-No.12

We present the results of high-resolution spectroscopy of the extremely luminous star CygOB2-No.12. We identified about 200 spectral features in the range 4552-7939 AA, including the interstellar NaI, KI lines and numerous very strong DIBs, along with the HeI, CII, and SiII lines. An MK spectral type we derived for the object is B4.5Ia+. Our analysis of the radial velocity data shows the presence of a gradient in the stellar atmosphere, caused by both atmospheric expansion and matter infall onto the star. The Halpha emission displays broad Thompson wings, a slightly blue-shifted PCyg type absorption component and a time-variable core absorption. We conclude that the wind is variable in time.Comment: 3 pages, 2 figures, IAU Symposium No.272 "Active OB stars: structure, evolution, mass loss and critical limits", 201

Sudden transitions and grand variations in the solar dynamo, past and future

The solar dynamo is the exotic dance of the sun's two major magnetic field components, the poloidal and the toroidal, interacting in anti-phase. On the basis of new data on the geomagnetic aa index, we improve our previous forecast of the properties of the current Schwabe cycle #24. Its maximum will occur in 2013.5 and the maximum sunspot number R-max will then be 62 +/- 12, which is within the bounds of our earlier forecasts. The subsequent analysis, based on a phase diagram, which is a diagram showing the relation between maximum sunspot numbers and minimum geomagnetic aa index values leads to the conclusion that a new Grand Episode in solar activity has started in 2008. From the study of the natural oscillations in the sunspot number time series, as found by an analysis based on suitable wavelet base functions, we predict that this Grand Episode will be of the Regular Oscillations type, which is the kind of oscillations that also occurred between 1724 and 1924. Previous expectations of a Grand (Maunder-type) Minimum of solar activity cannot be supported. We stress the significance of the Hallstatt periodicity for determining the character of the forthcoming Grand Episodes. No Grand Minimum is expected to occur during the millennium that has just started

Recent Analytical Methods for the Analysis of Sweeteners in Food: A Regulatory Perspective

Non-nutritive or low calorie sweeteners are commonly used worldwide in the food industry, often in combination in order to limit undesirable tastes. The list of allowable sweeteners varies among countries and it is important for regulatory agencies and food safety laboratories to monitor these highly consumed products to ensure compliance with worldwide regulations. Current analytical methods for confirmation and quantification of sweeteners must allow for confirmation of analyte identity in order to be compatible with today’s standards. Various methods for the determination of non-nutritive sweeteners have been reported in the literature. Th e most common multi-sweetener methods involve high performance liquid Th chromatography (HPLC) with different types of detection. The modern technique of HPLC-MS/MS is the current method of choice for the determination and confirmation of sweeteners in foods. In addition to multi-sweetener analyses there is also a need for single sweetener analytical methods in certain circumstances