An Imaging Polarimeter(IMPOL) for multi-wavelength observations

Taking advantage of the advances in array detector technology, an imaging polarimeter (IMPOL) has been constructed for measuring linear polarization in the wavelength band from 400-800 nm. It makes use of a Wollaston prism as the analyser to measure simultaneously the two orthogonal polarization components that define a Stoke's parameter. An achromatic half-wave plate is used to rotate the plane of polarization with respect to the axis of the analyser so that the second Stoke's parameter also can be determined. With a field of view correponding to about 30x30 sq. mm for a 1.2 m, f/13 telescope, a sensitive, liquid-nitrogen cooled CCD camera as the detector and a built-in acquisition and guidance unit, the instrument can be used for studying stellar fields or extended objects with an angular resolution close to 2 arcsec. The instrumental polarization is less than 0.05% and the accuracies of measurement are primarily limited by photon noise for typical observations.Comment: 10 pages including 5 embedded figures; submitted to Astronomy and Astrophysics Supplement Series; available on request to A. N. Ramaprakash ([email protected] or [email protected]); quote report n

A low-cost sensing system for quality monitoring of dairy products

The dairy industry is in need of a cost-effective, highly reliable, very accurate, and fast measurement system to monitor the quality of dairy products. This paper describes the design and fabrication works undertaken to develop such a system. The techniques used center around planar electromagnetic sensors operating with radio frequency excitation. Computer-aided computation, being fast, facilitates on-line monitoring of the quality. The sensor technology proposed has the ability to perform volumetric penetrative measurements to measure properties throughout the bulk of the product

Charged Particle with Magnetic Moment in the Aharonov-Bohm Potential

We considered a charged quantum mechanical particle with spin ${1\over 2}$ and gyromagnetic ratio $g\ne 2$ in the field af a magnetic string. Whereas the interaction of the charge with the string is the well kown Aharonov-Bohm effect and the contribution of magnetic moment associated with the spin in the case $g=2$ is known to yield an additional scattering and zero modes (one for each flux quantum), an anomaly of the magnetic moment (i.e. $g>2$) leads to bound states. We considered two methods for treating the case $g>2$. \\ The first is the method of self adjoint extension of the corresponding Hamilton operator. It yields one bound state as well as additional scattering. In the second we consider three exactly solvable models for finite flux tubes and take the limit of shrinking its radius to zero. For finite radius, there are $N+1$ bound states ($N$ is the number of flux quanta in the tube).\\ For $R\to 0$ the bound state energies tend to infinity so that this limit is not physical unless $g\to 2$ along with $R\to 0$. Thereby only for fluxes less than unity the results of the method of self adjoint extension are reproduced whereas for larger fluxes $N$ bound states exist and we conclude that this method is not applicable.\\ We discuss the physically interesting case of small but finite radius whereby the natural scale is given by the anomaly of the magnetic moment of the electron $a_e=(g-2)/2\approx 10^{-3}$.Comment: 16 pages, Latex, NTZ-93-0

Components of good end of life care within the paediatric intensive care setting – an online survey

BACKGROUND This study was undertaken to better understand the components of good end of life for children who are being cared for within the PICU. Cure rates from serious childhood illness are gradually improving every year. Despite this, there are still a small but significant number of children who will die within a Paediatric Intensive Care Unit. OBJECTIVES 1. The primary objective was to determine what the key aspects of End-of-Life-Care/palliative care in PICU as perceived by Health Professionals (including General Paediatricians) 2. This project will result in a schema of components of care which can be used by health professionals within in the intensive care setting to assist with excellent end of life care. METHOD An online survey of health professionals was used to rank various components of palliative care within the PICU context. Survey participants could also suggest other components of care that had not already been thought of within the survey. RESULTS There were 108 respondents who took the survey. The survey group were multidisciplinary (medical 32.4%; nursing 44.44% and allied health 23.15 %). There were also a variety of specialties represented in the survey (PICU 56.5 %; Paediatric Palliative Care 17.4%; General Paediatrics 13.9% and Other 12.2 %). The top 5 components of care ranked by the group included were identified by the interest groups after being ranked according to their importance. These included 1. Discussion of a Management Plan 2. Sensitive, compassionate use of language 3. Discussion of End of Life care 4. Discussion of anticipated changes in the patient's condition 5. Discussion of the caregiver's understanding of the illness. CONCLUSION It is hoped that the schema for good end of life care represents a consensus from a large and diverse group of health professionals. This schema should assist in the day to day care of patients. Further, it should also be of benefit in education, research and quality activities

A fixed point formula for the index of multi-centered N=2 black holes

We propose a formula for computing the (moduli-dependent) contribution of multi-centered solutions to the total BPS index in terms of the (moduli-independent) indices associated to single-centered solutions. The main tool in our analysis is the computation of the refined index Tr(-y)^{2J_3} of configurational degrees of freedom of multi-centered BPS black hole solutions in N=2 supergravity by localization methods. When the charges carried by the centers do not allow for scaling solutions (i.e. solutions where a subset of the centers can come arbitrarily close to each other), the phase space of classical BPS solutions is compact and the refined index localizes to a finite set of isolated fixed points under rotations, corresponding to collinear solutions. When the charges allow for scaling solutions, the phase space is non-compact but appears to admit a compactification with finite volume and additional non-isolated fixed points. We give a prescription for determining the contributions of these fixed submanifolds by means of a `minimal modification hypothesis', which we prove in the special case of dipole halo configurations.Comment: 61 pages, 3 figure

A Farey tale for N=4 dyons

We study exponentially suppressed contributions to the degeneracies of extremal black holes. Within Sen's quantum entropy function framework and focusing on extremal black holes with an intermediate AdS3 region, we identify an infinite family of semi-classical AdS2 geometries which can contribute effects of order exp(S_0/c), where S_0 is the Bekenstein-Hawking-Wald entropy and c is an integer greater than one. These solutions lift to the extremal limit of the SL(2,Z) family of BTZ black holes familiar from the "black hole Farey tail". We test this understanding in N=4 string vacua, where exact dyon degeneracies are known to be given by Fourier coefficients of Siegel modular forms. We relate the sum over poles in the Siegel upper half plane to the Farey tail expansion, and derive a "Farey tale" expansion for the dyon partition function. Mathematically, this provides a (formal) lift from Hilbert modular forms to Siegel modular forms with a pole at the diagonal divisor.Comment: 31 page