Optimal Quantum Metrology of Distant Black Bodies

Measurements of an object's temperature are important in many disciplines, from astronomy to engineering, as are estimates of an object's spatial configuration. We present the quantum optimal estimator for the temperature of a distant body based on the black body radiation received in the far-field. We also show how to perform separable quantum optimal estimates of the spatial configuration of a distant object, i.e. imaging. In doing so we necessarily deal with multi-parameter quantum estimation of incompatible observables, a problem that is poorly understood. We compare our optimal observables to the two mode analogue of lensed imaging and find that the latter is far from optimal, even when compared to measurements which are separable. To prove the optimality of the estimators we show that they minimise the cost function weighted by the quantum Fisher information---this is equivalent to maximising the average fidelity between the actual state and the estimated one.Comment: 12 pages, 6 figure

Moontlike ruimtelike oplossings vir gesinne en gemeenskappe waar die gesinstruktuur verander het weens MIV/VIGS

HIV/AIDS changes the familial structure of society. The town and regional planner must respond to this phenomenon in spatial terms. In this paper, the consequences of HIV/AIDS for the family are investigated. During the first phase, proposals for the spatial resolution of these consequences were submitted to the community as part of a test sample. Thereafter, the proposals were taken to the relief organisations working with AIDS sufferers and AIDS victims within the community. Since HIV/AIDS affects the human being in his/her totality, the action taken must be multidisciplinary in nature. The leaders in the community, as well as the various government departments and non-government organizations, must all be involved, in order to deal with this problem.*Article written in Afrikaans

Catheter insertion techniques for improving catheter function and clinical outcomes in peritoneal dialysis patients (Protocol)

This is a protocol for a Cochrane Review (Intervention). The objectives are as follows: This review aims to look at the benefits and harms of different PD catheter insertion techniques. To establish whether a specific technique used to place catheters in adults and children, who are new to PD, result in any significant differences in clinical outcomes. Insertion techniques will be further defined as peritoneoscopic, percutaneous, fluoroscopic, laparoscopic insertion or open surgery. To identify which technique offers optimal clinical outcomes and minimises post-procedure complications including postoperative haemorrhage, PD catheter dysfunction, exit site infection/peritonitis and bowel perforation

Study of ATLAS sensitivity to FCNC top decays

The ATLAS experiment sensitivity to top quark Flavour Changing Neutral Current (FCNC) decays was studied at LHC using ttbar events. While one of the top quarks is expected to follow the dominant Standard Model decay t->bW, the other decays through a FCNC channel, i.e. t-> Z u(c), t-> gamma u(c) or t-> g u(c). Different types of analyses, applied to each FCNC decay mode, were compared. The FCNC branching ratio sensitivity (assuming a 5sigma signal significance) and 95% confidence level limits on the branching ratios (in the hypothesis of signal absence) were obtained

Triplet superconductivity in quasi one-dimensional systems

We study a Hubbard hamiltonian, including a quite general nearest-neighbor interaction, parametrized by repulsion V, exchange interactions Jz, Jperp, bond-charge interaction X and hopping of pairs W. The case of correlated hopping, in which the hopping between nearest neighbors depends upon the occupation of the two sites involved, is also described by the model for sufficiently weak interactions. We study the model in one dimension with usual continuum-limit field theory techniques, and determine the phase diagram. For arbitrary filling, we find a very simple necessary condition for the existence of dominant triplet superconducting correlations at large distance in the spin SU(2) symmetric case: 4V+J<0. In the correlated hopping model, the three-body interaction should be negative for positive V. We also compare the predictions of this weak-coupling treatment with numerical exact results for the correlated-hopping model obtained by diagonalizing small chains, and using novel techniques to determine the opening of the spin gap.Comment: 8 pages, 3 figure

Chiral and Gluon Condensates at Finite Temperature

We investigate the thermal behaviour of gluon and chiral condensates within an effective Lagrangian of pseudoscalar mesons coupled to a scalar glueball. This Lagrangian mimics the scale and chiral symmetries of QCD. (Submitted to Z. Phys. C)Comment: 20 pages + 7 figures (uuencoded compressed postscript files), University of Regensburg preprint TPR-94-1

Soft gluons in Higgs plus two jet production

We investigate the effects of an all order QCD resummation of soft gluon emissions for Higgs boson production in association with two hard jets. We consider both the gluon-gluon fusion and weak boson fusion processes and show how to resum a large part of the leading logarithms in the jet veto scale. Our resummation improves on previous analyses which also aim to include the effects of multiple soft gluon radiation. In addition we calculate the interference between weak boson fusion and gluon-gluon fusion and find that it is small.Comment: 15 pages and 5 figure

Two-loop QCD corrections to the scattering of massless distinct quarks.

We present the two-loop virtual QCD corrections to the scattering of distinct massless quarks, , in conventional dimensional regularisation. The structure of the infrared divergences agrees with that predicted by Catani while expressions for the finite remainder are given for each of the s-, t- and u-channels in terms of polylogarithms. The results presented here form a vital part of the next-to-next-to-leading order contribution to inclusive jet production in hadron colliders and will play a crucial role in improving the theoretical prediction for jet cross sections in hadron-hadron collisions

Strongly correlated hopping and many-body bound states

We study a system in which the quantum dynamics of electrons depend on the particle density in their neighborhood. For any on-site repulsive interaction, we show that the exact two-body and three-body ground states are bound states. We also discuss the finite density case in a mean-field framework and we show that the system can undergo an unusual transition from an effective attractive interaction to a repulsive one, when varying the electron density.Comment: 6 pages, 6 EPS figures, minor modifications and references adde