Non trivial generalizations of the Schwinger pair production result

We present new, non trivial generalizations of the recent Tomaras, Tsamis and Woodard extension of the original Schwinger formula for charged pair production in a constant field.Comment: 11 page

Alternating groups and moduli space lifting Invariants

Main Theorem: Spaces of r-branch point 3-cycle covers, degree n or Galois of degree n!/2 have one (resp. two) component(s) if r=n-1 (resp. r\ge n). Improves Fried-Serre on deciding when sphere covers with odd-order branching lift to unramified Spin covers. We produce Hurwitz-Torelli automorphic functions on Hurwitz spaces, and draw Inverse Galois conclusions. Example: Absolute spaces of 3-cycle covers with +1 (resp. -1) lift invariant carry canonical even (resp. odd) theta functions when r is even (resp. odd). For inner spaces the result is independent of r. Another use appears in, http://www.math.uci.edu/~mfried/paplist-mt/twoorbit.html, "Connectedness of families of sphere covers of A_n-Type." This shows the M(odular) T(ower)s for the prime p=2 lying over Hurwitz spaces first studied by, http://www.math.uci.edu/~mfried/othlist-cov/hurwitzLiu-Oss.pdf, Liu and Osserman have 2-cusps. That is sufficient to establish the Main Conjecture: (*) High tower levels are general-type varieties and have no rational points.For infinitely many of those MTs, the tree of cusps contains a subtree -- a spire -- isomorphic to the tree of cusps on a modular curve tower. This makes plausible a version of Serre's O(pen) I(mage) T(heorem) on such MTs. Establishing these modular curve-like properties opens, to MTs, modular curve-like thinking where modular curves have never gone before. A fuller html description of this paper is at http://www.math.uci.edu/~mfried/paplist-cov/hf-can0611591.html .Comment: To appear in the Israel Journal as of 1/5/09; v4 is corrected from proof sheets, but does include some proof simplification in \S

Superwind-driven Intense H2_2 Emission in NGC 6240 II: Detailed Comparison of Kinematical and Morphological Structures of the Warm and Cold Molecular Gas

We report on our new analysis of the spatial and kinematical distribution of warm and cold molecular gas in NGC 6240, which was undertaken to explore the origin of its unusually luminous H$_2$ emission. By comparing three-dimensional emission-line data (in space and velocity) of CO (J=2-1) in the radio and H$_2$ in the near infrared, we are able to study the H$_2$ emitting efficiency, defined in terms of the intensity ratio of H$_2$ to CO [$I$(H$_2$)/$I$(CO)], as a function of velocity. The integrated H$_2$ emitting efficiency is calculated by integrating the velocity profile of H$_2$ emitting efficiency in blue, red, and total (blue + red) velocity regions of the profile. We find that (1) both the total H$_2$ emitting efficiency and the blue-to-red ratio of the efficiency are larger in regions surrounding the CO and H$_2$ intensity peaks, and (2) the H$_2$ emitting efficiency and the kinematical conditions in the warm molecular gas are closely related to each other. A collision between the molecular gas concentration and the external superwind outflow from the southern nucleus seems plausible to explain these characteristics, since it can reproduce the enhanced emitting efficiency of blueshifted H$_2$ around the molecular gas concentration, if we assume that the superwind blows from the southern nucleus toward us, hitting the entire gas concentration from behind. In this model, internal cloud-cloud collisions within the molecular gas concentration are enhanced by the interaction with the superwind outflow, and efficient and intense shock-excited H$_2$ emission is expected as a result of the cloud-crushing mechanism.Comment: 12 pages, 6 figures, accepted for publication in A

About the morphology of dwarf spheroidal galaxies and their dark matter content

The morphological properties of the Carina, Sculptor and Fornax dwarfs are investigated using new wide field data with a total area of 29 square degrees. The stellar density maps are derived, hinting that Sculptor possesses tidal tails indicating interaction with the Milky Way. Contrary to previous studies we cannot find any sign of breaks in the density profiles for the Carina and Fornax dwarfs. The possible existence of tidal tails in Sculptor and of King limiting radii in Fornax and Carina are used to derive global M/L ratios, without using kinematic data. By matching those M/L ratios to kinematically derived values we are able to constrain the orbital parameters of the three dwarfs. Fornax cannot have M/L smaller than 3 and must be close to its perigalacticon now. The other extreme is Sculptor that needs to be on an orbit with an eccentricity bigger than 0.5 to be able to form tidal tails despite its kinematic M/L.Comment: 9 pages, 7 figures, accepted by A&

Integration of the atmospheric fluctuations in a dual-field optical interferometer: the short exposure regime

Spatial phase-referencing in dual-field optical interferometry is reconsidered. Our analysis is based on the 2-sample variance of the differential phase between target and reference star. We show that averaging over time of the atmospheric effects depends on this 2-sample phase variance (Allan variance) rather than on the true variance. The proper expression for fringe smearing beyond the isoplanatic angle is derived. With simulations of atmospheric effects, based on a Paranal turbulence model, we show how the performances of a dual-field optical interferometer can be evaluated in a diagram 'separation angle' versus 'magnitude of faint object'. In this diagram, a domain with short exposure is found to be most useful for interferometry, with about the same magnitude limits in the H and K bands. With star counts from a Galaxy model, we evaluate the sky coverage for differential astrometry and detection of exoplanets, i.e. likelihood of faint reference stars in the vicinity of a bright target. With the 2mass survey, we evaluate sky coverage for phase-referencing, i.e. avaibility of a bright enough star for main delay tracking in the vicinity of any target direction.Comment: 9 pages, 8 figures, accepted for publication in A&

Determination of complex dielectric functions of ion implanted and implanted‐annealed amorphous silicon by spectroscopic ellipsometry

Measuring with a spectroscopic ellipsometer (SE) in the 1.8–4.5 eV photon energy region we determined the complex dielectric function (ϵ = ϵ1 + iϵ2) of different kinds of amorphous silicon prepared by self‐implantation and thermal relaxation (500 °C, 3 h). These measurements show that the complex dielectric function (and thus the complex refractive index) of implanted a‐Si (i‐a‐Si) differs from that of relaxed (annealed) a‐Si (r‐a‐Si). Moreover, its ϵ differs from the ϵ of evaporated a‐Si (e‐a‐Si) found in the handbooks as ϵ for a‐Si. If we use this ϵ to evaluate SE measurements of ion implanted silicon then the fit is very poor. We deduced the optical band gap of these materials using the Davis–Mott plot based on the relation: (ϵ2E2)1/3 ∼ (E− Eg). The results are: 0.85 eV (i‐a‐Si), 1.12 eV (e‐a‐Si), 1.30 eV (r‐a‐Si). We attribute the optical change to annihilation of point defects

Settlement Types and Community Organization in Northern Canada

Summarizes 1961-1962 field studies of settlements resulting from post-World War II development in the Northwest Territories. On criteria of community planning, function, and social structure, seven settlement types are distinguished: isolated technical, e.g. weather stations; military; outpost service, e.g. Dorset; serviced native enclave, e.g. Akudlik at Churchill; regional administrative; frontier; and mining. Each type is characterized as to social organization and population. Civil servants, as to their reaction to settlement life, as is the white settlers, and aboriginals are noted danger of arrested cultural transition among the aboriginals