Electrodynamics at non-zero temperature, chemical potential, and Bose condensate

Electrodynamics of charged scalar bosons and spin 1/2 fermions is studied at non-zero temperature, chemical potentials, and possible Bose condensate of the charged scalars. Debye screening length, plasma frequency, and the photon dispersion relation are calculated. It is found that in presence of the condensate the time-time component of the photon polarization operator in the first order in electric charge squared acquires infrared singular parts proportional to inverse powers of the spatial photon momentum k.Comment: Two references and explanatory comments are added according to the referee's suggestions. The paper is accepted for publication in JCA

Effective potential at finite temperature in a constant hypermagnetic field: Ring diagrams in the Standard Model

We study the symmetry breaking phenomenon in the standard model during the electroweak phase transition in the presence of a constant hypermagnetic field. We compute the finite temperature effective potential up to the contribution of ring diagrams in the weak field, high temperature limit and show that under these conditions, the phase transition becomes stronger first order.Comment: 15 pages, 8 Postscript figure

Unusual cytotoxic sulfated cadinene-type sesquiterpene glycosides from cottonseed (Gossypium hirsutum).

Two new sulfated cadinene-type sesquiterpene glycosides, 13-hydroxy-7-O-(60-O-sulfate-b-D-glucopyranosyl)-desoxyhemigossypol (1) and 13,15-dihydroxy-7-O-(60-O-sulfate-b-D-glucopyranosyl)-desoxyhemigossypol (2), have been isolated from whole cottonseed (Gossypium hirsutum). Their structures, which possess an unusual 6-O-sulfate-glucopyranosyl moiety, were determined through the interpretation of 2D NMR spectral data and H/D exchange ESI-MS experiments. Compounds 1 and 2 were screened for their toxicity on Jurkat cells. Both compounds inhibited cellular proliferation with IC50 values of 8.1 and 4.2 mg, respectively

Improving Rigid 3-D Calibration for Robotic Surgery

Autonomy is the next frontier of research in robotic surgery and its aim is to improve the quality of surgical procedures in the next future. One fundamental requirement for autonomy is advanced perception capability through vision sensors. In this article, we propose a novel calibration technique for a surgical scenario with a da Vinci Research Kit (dVRK) robot. Camera and robotic arms calibration are necessary to precise position and emulate expert surgeon. The novel calibration technique is tailored for RGB-D cameras. Different tests performed on relevant use cases prove that we significantly improve precision and accuracy with respect to state of the art solutions for similar devices on a surgical-size setups. Moreover, our calibration method can be easily extended to standard surgical endoscope used in real surgical scenario

Real-time Chern-Simons term for hypermagnetic fields

If non-vanishing chemical potentials are assigned to chiral fermions, then a Chern-Simons term is induced for the corresponding gauge fields. In thermal equilibrium anomalous processes adjust the chemical potentials such that the coefficient of the Chern-Simons term vanishes, but it has been argued that there are non-equilibrium epochs in cosmology where this is not the case and that, consequently, certain fermionic number densities and large-scale (hypermagnetic) field strengths get coupled to each other. We generalise the Chern-Simons term to a real-time situation relevant for dynamical considerations, by deriving the anomalous Hard Thermal Loop effective action for the hypermagnetic fields, write down the corresponding equations of motion, and discuss some exponentially growing solutions thereof.Comment: 13 page

The effects of Non-Gaussian initial conditions on the structure and substructure of Cold Dark Matter halos

We study the structure and substructure of halos obtained in N-body simulations for a Lambda Cold Dark Matter (LCDM) cosmology with non-Gaussian initial conditions (NGICs). The initial statistics are lognormal in the gravitational potential field with positive (LNp) and negative (LNn) skewness; the sign of the skewness is conserved by the density field, and the power spectrum is the same for all the simulations. Our aim is not to test a given non-Gaussian statistics, but to explore the generic effect of positive- and negative-skew statistics on halo properties. From our low-resolution simulations, we find that LNp (LNn) halos are systematically more (less) concentrated than their Gaussian counterparts. This result is confirmed by our Milky Way- and cluster-sized halos resimulated with high-resolution. In addition, they show inner density profiles that depend on the statistics: the innermost slopes of LNp (LNn) halos are steeper (shallower) than those obtained from the corresponding Gaussian halos. A subhalo population embedded in LNp halos is more susceptible to destruction than its counterpart inside Gaussian halos. On the other hand, subhalos in LNn halos tend to survive longer than subhalos in Gaussian halos. The spin parameter probability distribution of LNp (LNn) halos is skewed to smaller (larger) values with respect to the Gaussian case. Our results show how the statistics of the primordial density field can influence some halo properties, opening this the possibility to constrain, although indirectly, the primordial statistics at small scale.Comment: 15 pages, 8 figures. Slight corrections after referee report. To appear in ApJ, v598, November 20, 200

Exact inflationary solutions

We present a new class of exact inflationary solutions for the evolution of a universe with spatial curvature, filled with a perfect fluid, a scalar field with potential $V_{\pm}(\phi)=\lambda(\phi^2\pm\delta^2)^2$ and a cosmological constant $\Lambda$. With the $V_+(\phi)$ potential and a negative cosmological constant, the scale factor experiments a graceful exit. We give a brief discussion about the physical meaning of the solutions.Comment: 10 pages, revtex file, 6 figures included with epsf. To be published in IJMP-

Baryogenesis and CP-Violating Domain Walls in the Background of a Magnetic Field

Within the domain wall-mediated electroweak baryogenesis, we study fermion scattering off a CP-violating wall in the background of an uniform magnetic field. In particular, we calculate the asymmetry between the reflection coefficients for right-handed and left-handed chiral fermions, \Delta R = R_{R \to L} - R_{L \to R}, which is of relevance to non local baryogenesis mechanisms.Comment: replaced with revised conclusion version, to be published in JCA