Status of the ANTARES Project

The ANTARES collaboration is constructing a neutrino telescope in the Mediterranean Sea at a depth of 2400 metres, about 40 kilometres off the French coast near Toulon. The detector will consist of 12 vertical strings anchored at the sea bottom, each supporting 25 triplets of optical modules equipped with photomultipliers, yielding sensitivity to neutrinos with energies above some 10 GeV. The effective detector area is roughly 0.1 square kilometres for neutrino energies exceeding 10 TeV. The measurement of the Cherenkov light emitted by muons produced in muon-neutrino charged-current interactions in water and under-sea rock will permit the reconstruction of the neutrino direction with an accuracy of better than 0.3 degrees at high energies. ANTARES will complement the field of view of neutrino telescopes at the South Pole in the low-background searches for point-sources of high-energy cosmic neutrinos and will also be sensitive to neutrinos produced by WIMP annihilation in the Sun or the Galactic centre.Comment: 3 pages, 3 figures, to appear in Proc. HEP2003 Europhysics Conf., Aachen, Germany, 17-23 July 200

Effects of aminoperimidine on electrolyte transport across amphibian skin

The effect of aminoperimidine (AP)on transepithelial Na+ transport and Cl- conductance (G(Cl)) of isolated amphibian skin (Bufo viridis and Rana esculenta) was analyzed using transepithelial and intracellular electrophysiological techniques. AP, applied at concentrations between 30 and 100 mu M from the mucosal side, stimulated Na+ transport rapidly and reversibly by more than 30% of the control value due to an increase in apical membrane Na+ permeability. Influence of AP on basolateral membrane conductance and effective driving force for Na+ were negligible. Voltage-activated G(Cl) of toad skin, but not the resting, deactivated conductance, as well as spontaneously high G(Cl) in frog skin was rapidly inhibited by AP in a concentration-dependent manner. The half-maximal inhibitory concentration of 20 mu M is the highest hithero reported inhibitory power for G(Cl) in amphibian skin. The effect of AP on G(Cl) was slowly and incompletely reversible even after brief exposure to the agent. Serosal application of AP had similar, albeit delayed effects on both Nai and Cl- transport. AP did not interfere with the Cl- pathway after it was opened by 100-300 mu M CPT-cAMP, a membrane-permeable, nonhydrolyzed analogue of cAMP. Inhibition of the voltage-activated G(Cl) by AP was attenuated or missing when AP was applied during voltage perturbation to serosa-positive potentials. Since AP is positively charged at physiological pH, it suggests that the affected site is located inside the Cl- pathway at a certain distance from the external surface. AP affects then the Na+ and Cl- transport pathways independent of each other. The nature of chemical interference with AP, which is responsible for the influence on the transport of Na+ and Cl-, remains to be elucidated

A Conformal Truncation Framework for Infinite-Volume Dynamics

We present a new framework for studying conformal field theories deformed by one or more relevant operators. The original CFT is described in infinite volume using a basis of states with definite momentum, $P$, and conformal Casimir, $\mathcal{C}$. The relevant deformation is then considered using lightcone quantization, with the resulting Hamiltonian expressed in terms of this CFT basis. Truncating to states with $\mathcal{C} \leq \mathcal{C}_{\max}$, one can numerically find the resulting spectrum, as well as other dynamical quantities, such as spectral densities of operators. This method requires the introduction of an appropriate regulator, which can be chosen to preserve the conformal structure of the basis. We check this framework in three dimensions for various perturbative deformations of a free scalar CFT, and for the case of a free $O(N)$ CFT deformed by a mass term and a non-perturbative quartic interaction at large-$N$. In all cases, the truncation scheme correctly reproduces known analytic results. We also discuss a general procedure for generating a basis of Casimir eigenstates for a free CFT in any number of dimensions.Comment: 48+37 pages, 17 figures; v2: references added, small clarification

Relative systoles of relative-essential 2-complexes

We prove a systolic inequality for the phi-relative 1-systole of a phi-essential 2-complex, where phi is a homomorphism from the fundamental group of the complex, to a finitely presented group G. Indeed we show that universally for any phi-essential Riemannian 2-complex, and any G, the area of X is bounded below by 1/8 of sys(X,phi)^2. Combining our results with a method of Larry Guth, we obtain new quantitative results for certain 3-manifolds: in particular for Sigma the Poincare homology sphere, we have sys(Sigma)^3 < 24 vol(Sigma).Comment: 20 pages, to appear in Algebraic and Geometric Topolog

Project Fog Drops 5. Task 1: A numerical model of advection fog. Task 2: Recommendations for simplified individual zero-gravity cloud physics experiments

A two-dimensional numerical model was used to investigate the formation of marine advection fog. The model predicts the evolution of potential temperature, horizontal wind, water vapor content, and liquid water content in a vertical cross section of the atmosphere as determined by vertical turbulent transfer and horizontal advection, as well as radiative cooling and drop sedimentation. The model is designed to simulate the formation, development, or dissipation of advection fog in response to transfer of heat and moisture between the atmosphere and the surface as driven by advection over horizontal discontinuities in the surface temperature. Results from numerical simulations of advection fog formation are discussed with reference to observations of marine fog. A survey of candidate fog or cloud microphysics experiments which might be performed in the low gravity environment of a shuttle-type spacecraft in presented. Recommendations are given for relatively simple experiments which are relevent to fog modification problems

The spectral-curvature parameter: an alternative tool for the analysis of synchrotron spectra

The so-called Spectral Curvature Parameter(SCP), when plotted versus the high-frequency spectral index ($alpha_{high}$) of synchrotron sources, provides crucial parameters on the continuum spectrum of synchrotron radiation without the more complex modeling of spectral ageing scenarios. An important merit of the SCP-$alpha$ diagram is the enhanced reliability of extracting multiple injection spectra, $alpha_{inj}$. Different from the colour-colour diagram, tracks of different $alpha_{inj}$s, especially when the synchrotron particles are young, exhibit less overlap and less smearing in the SCP-$alpha$ diagram. Three giant radio galaxies(GRGs) and a sample of Compact steep spectrum(CSS) souces are presented. GRGs exhibit asymmetries of their injection spectral indices $alpha_{inj}$ in the SCP-$alpha_{high}$ diagram. The obtained $alpha_{inj}$s and the trends in the sources are cross-checked with the literature and show remarkable confidence. Besides the spectral steepening, spectral flattening is prominent in the radio lobes. The spectral flattening is a clue to efficient re-acceleration processes in the lobes. It implies interaction with the surrounding intergalactic or intra-cluster medium is an important characteristic of GRGs. In the SW lobe of DA240, there is a clear sign of CI and KP/JP bifurcation at the source extremity. This indicates a highly relativistic energy transportation from the core or in situ acceleration in this typical FR I lobe. Our analysis proves, if exists, KP spectra imply the existence of strong $B_{sync}$ field with $B_{sync} > B_{CMB}$. In the CSS sources, our result confirms the CI model and $B_{sync} >> B_{CMB}$. The synchrotron self-absorption is significant in the CSS sample.Comment: to be published in A&