VLBI observations of SN2011dh: imaging of the youngest radio supernova

We report on the VLBI detection of supernova SN2011dh at 22GHz using a subset of the EVN array. The observations took place 14 days after the discovery of the supernova, thus resulting in a VLBI image of the youngest radio-loud supernova ever. We provide revised coordinates for the supernova with milli-arcsecond precision, linked to the ICRF. The recovered flux density is a factor 2 below the EVLA flux density reported by other authors at the same frequency and epoch of our observations. This discrepancy could be due to extended emission detected with the EVLA or to calibration problems in the VLBI and/or EVLA observations.Comment: Letter. Accepted in A&

Observation of anisotropic diamagnetism above the superconducting transition in iron-pnictide Ba_(1-x)K_xFe2As2 single crystals due to thermodynamic fluctuations

High resolution magnetization measurements performed in a high quality Ba_(1-x)K_xFe2As2 single crystal allowed to determine the diamagnetism induced above the superconducting transition by thermally activated Cooper pairs. These data, obtained with magnetic fields applied along and transverse to the crystal ab layers, demonstrate experimentally that the superconducting transition of iron pnictides may be explained at a phenomenological level in terms of the Gaussian Ginzburg-Landau approach for three-dimensional anisotropic superconductors.Comment: Final version with minor corrections. 6 pages, 4 figure

Evolution equation of entanglement for general bipartite systems

We explore how entanglement of a general bipartite system evolves when one subsystem undergoes the action of an arbitrary noisy channel. It is found that the dynamics of entanglement for general bipartite systems under the influence of such channel is determined by the channel's action on the maximally entangled state, which includes as a special case the results for two-qubit systems [Nature Physics 4, 99 (2008)]. In particular, for multi-qubit or qubit-qudit systems, we get a general factorization law for evolution equation of entanglement with one qubit being subject to a noisy channel. Our results can help the experimental characterization of entanglement dynamics.Comment: 4 pages, 1 figur

Laser-assisted guiding of electric discharges around objects

Electric breakdown in air occurs for electric fields exceeding 34 kV/cm and results in a large current surge that propagates along unpredictable trajectories. Guiding such currents across specific paths in a controllable manner could allow protection against lightning strikes and high-voltage capacitor discharges. Such capabilities can be used for delivering charge to specific targets, for electronic jamming, or for applications associated with electric welding and machining. We show that judiciously shaped laser radiation can be effectively used to manipulate the discharge along a complex path and to produce electric discharges that unfold along a predefined trajectory. Remarkably, such laser-induced arcing can even circumvent an object that completely occludes the line of sight

The Relativistic Levinson Theorem in Two Dimensions

In the light of the generalized Sturm-Liouville theorem, the Levinson theorem for the Dirac equation in two dimensions is established as a relation between the total number $n_{j}$ of the bound states and the sum of the phase shifts $\eta_{j}(\pm M)$ of the scattering states with the angular momentum $j$: $$\eta_{j}(M)+\eta_{j}(-M)~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ \~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~$$ $$~~~=\left\{\begin{array}{ll} (n_{j}+1)\pi &{\rm when~a~half~bound~state~occurs~at}~E=M ~~{\rm and}~~ j=3/2~{\rm or}~-1/2\\ (n_{j}+1)\pi &{\rm when~a~half~bound~state~occurs~at}~E=-M~~{\rm and}~~ j=1/2~{\rm or}~-3/2\\ n_{j}\pi~&{\rm the~rest~cases} . \end{array} \right.$$ \noindent The critical case, where the Dirac equation has a finite zero-momentum solution, is analyzed in detail. A zero-momentum solution is called a half bound state if its wave function is finite but does not decay fast enough at infinity to be square integrable.Comment: Latex 14 pages, no figure, submitted to Phys.Rev.A; Email: [email protected], [email protected]

Diet, sex, and social status in the Late Avar period: stable isotope investigations at Nuštar cemetery, Croatia

Diet often plays a vital role in defining social divisions within and between social groups and thus can be used to understand the social paradigms of archaeological cultures. During the Early Avar period (568 – 630 A.D.), burial evidence indicates that there were strong demarcations of social stratification, and divisions between sexes and age groups; however, the symbols of intra-population heterogeneity become increasingly rare during the Late Avar period (680 – 822 A.D.). In this study, we investigate social differences expressed through diet in the cemetery population from Nuštar, eastern Croatia (8th to early 9th century), to determine whether dietary social disparities existed during the Late Avar period in this region. Stable isotope analysis of carbon (δ13C) and nitrogen (δ15N) from bone and dentine collagen show no dietary differences, neither between high, middle and low status individuals, nor between males, females and juveniles. These results likely reflect the outcome of the social homogenization process that began after the failed Avar attack on Constantinople in 626 A.D. Geographical patterning is visible when the data from Nuštar is compared to data from other Middle and Late Avar sites. While Avar sites in the southern and south-eastern frontiers of the Avar qaganate do not display dietary differences between sexes, previous isotopic work on populations in Lower Austria show that males consumed a higher proportion of animal protein than females. This is likely the result of Frankish influence and reflects diversity in social practices within the Avar qaganate itself during the Middle and Late Avar periods

Choosing more mathematics : happiness through work?

This paper examines how A-level students construct relationships between work and happiness in their accounts of choosing mathematics and further mathematics A-level. I develop a theoretical framework that positions work and happiness as opposed, managed and working on the self and use this to examine students' dual engagement with individual practices of the self and institutional practices of school mathematics. Interviews with students acknowledge four imperatives that they use as discursive resources to position themselves as successful/unsuccessful students: you have to work, you have to not work, you have to be happy, you have to work at being happy. Tensions in these positions lead students to rework their identities or drop further mathematics. I then identify the practices of mathematics teaching that students use to explain un/happiness in work, and show how dependable mathematics and working together are constructed as 'happy objects' for students, who develop strategies for claiming control over these shapers of happiness. © 2010 British Society for Research into Learning Mathematics

Levinson's Theorem for the Klein-Gordon Equation in Two Dimensions

The two-dimensional Levinson theorem for the Klein-Gordon equation with a cylindrically symmetric potential $V(r)$ is established. It is shown that $N_{m}\pi=\pi (n_{m}^{+}-n_{m}^{-})= [\delta_{m}(M)+\beta_{1}]-[\delta_{m}(-M)+\beta_{2}]$, where $N_{m}$ denotes the difference between the number of bound states of the particle $n_{m}^{+}$ and the ones of antiparticle $n_{m}^{-}$ with a fixed angular momentum $m$, and the $\delta_{m}$ is named phase shifts. The constants $\beta_{1}$ and $\beta_{2}$ are introduced to symbol the critical cases where the half bound states occur at $E=\pm M$.Comment: Revtex file 14 pages, submitted to Phys. Rev.

Morbilidad de la linfadenectomía lumboaórtica laparoscópica en pacientes con tumor testicular no seminomatoso en estadío clínico A

Indexación: ScieloRetroperitoneal Lymph node dissection is part of the treatment of patients with nonseminomatous germ cell tumors stage I (NSGCT). Aim: To report the immediate surgical outcomes of patients subjected to laparoscopic retroperitoneal lymph node dissection. Material and Methods: Prospective analysis of the surgical outcomes of 118 patients aged 15 to 44 years, who underwent Laparoscopic Retroperitoneal Lymph Node Dissection (L-RPLND) for NSGCT stage I. Results: Median blood loss was 50 cc (range 10-1.000 cc), median operative time was 120 min. (range 60-300 min). Mean hospital stay was 41.4 hours. Twelve patients (10.2%) had operative complications. Ten had vascular injuries (8.5%), one had a duodenal injury (0.85%) and one had an acute pulmonary edema (0.85%). Eight lesions were repaired laparoscopically and three required conversion to open surgery. There was no mortality in this series. Conclusions: L-RPLND had an acceptable complication rate in this series of patients. Most of the complications could be resolved laparoscopicallyIntroducción: La linfadenectomía retroperitoneal lumboaórtica es el método de elección en el tratamiento de los pacientes con cáncer testicular no seminoma en estadio A. Este trabajo muestra los resultados inmediatos de una serie de 118 pacientes operados por vía laparoscópica. Material y Método: Se analizan los resultados quirúrgicos de 118 pacientes portadores de un cáncer testicular no seminoma estadio clínico A. Resultados: La media de edad fue de 29 años. La mediana de sangrado fue de 50 cc, el tiempo quirúrgico tuvo una mediana de 120 minutos y el tiempo de hospitalización tuvo una media de 41,4 horas. Complicaciones intraoperatorias ocurrieron en 12 pacientes (10,2%): 10 lesiones hemorrágicas (8,5%), 1 lesión duodenal (0,85%) y 1 edema pulmonar agudo (0,85%). De las 11 lesiones quirúrgicas, 8 fueron reparadas por vía laparoscópica, requiriendo conversión a cirugía abierta 3 casos. No hubo mortalidad en la serie. Conclusiones: La linfadenectomía lumboaórtica laparoscópica es un procedimiento estandarizado, con una tasa de complicaciones aceptable, la mayoría de las cuales puede ser resuelta en forma laparoscópica