Anderson localization on the Cayley tree : multifractal statistics of the transmission at criticality and off criticality

In contrast to finite dimensions where disordered systems display multifractal statistics only at criticality, the tree geometry induces multifractal statistics for disordered systems also off criticality. For the Anderson tight-binding localization model defined on a tree of branching ratio K=2 with $N$ generations, we consider the Miller-Derrida scattering geometry [J. Stat. Phys. 75, 357 (1994)], where an incoming wire is attached to the root of the tree, and where $K^{N}$ outcoming wires are attached to the leaves of the tree. In terms of the $K^{N}$ transmission amplitudes $t_j$, the total Landauer transmission is $T \equiv \sum_j | t_j |^2$, so that each channel $j$ is characterized by the weight $w_j=| t_j |^2/T$. We numerically measure the typical multifractal singularity spectrum $f(\alpha)$ of these weights as a function of the disorder strength $W$ and we obtain the following conclusions for its left-termination point $\alpha_+(W)$. In the delocalized phase $W<W_c$, $\alpha_+(W)$ is strictly positive $\alpha_+(W)>0$ and is associated with a moment index $q_+(W)>1$. At criticality, it vanishes $\alpha_+(W_c)=0$ and is associated with the moment index $q_+(W_c)=1$. In the localized phase $W>W_c$, $\alpha_+(W)=0$ is associated with some moment index $q_+(W)<1$. We discuss the similarities with the exact results concerning the multifractal properties of the Directed Polymer on the Cayley tree.Comment: v2=final version (16 pages

UA3/3/1 Analysis of the Demand for Married Student Housing at WKU, 1966-1967

The purpose of this study is to bring forth relevant information needed to determine the feasibility of an investment project for a married student housing complex on the campus of Western Kentucky University. Only the demand side of the market is analyzed; a potential investor will have the construction and land costs for such an enterprise at his disposal. With the information presented in this study it is hoped that a decision to construct a housing complex will be forthcoming. The study group attempted to present information that will allow a potential investor to make an intelligent decision as to the profitability of the investment. It is hoped that the critical questions concerning the investment have been answered by this study. The time period in which the study was carried out was January, 1967 to June, 1967, i.e., the second semester of the 1966-67 school year. The information presented was obtained from a single sample of the married population. Seventy married family units (8.4 percent of the population) were stratified according to class standing (Freshman, Sophomore, Junior, Senior, and Graduate) and then picked randomly within the class stratifications. A more desirable method would have been a sequential sampling method, but the time and expense of the method did not allow its use. Future studies can be carried out in order to substantiate the data presented at this time. The estimated size of the investment would seem to warrant at least one more comprehensive examination of the market in order that a more exact market character can be determined. The study group contacted state institutions that have married housing units in order to see if any useful information could be obtained from their experience in the determination of market character and size of their married students. None of the schools contacted had conducted a market study prior to the construction of such a housing unit. Discovering this factor did not disturb the study group. It was assumed that the market character at the various educational institutions would be significantly different with reference to income, rent, family size, etc., that no useful comparison could be made. The reason for this assumption rests on the fact that the educational institutions differ in such things as type and size of the graduate program and community size and industrial development. These factors have a direct influence on the family unit\u27s income, numbers, and the rate of growth of the married student body. The purpose of contacting the various institutions was to examine the methodology used in the study of the market for married student housing

A Method for Compiling and Executing Expressive Assertions

Programming with assertions constitutes an effective tool to detect and correct programming errors. The ability of executing formal specifications is essential in order to test automatically a program with respect to its assertions. However, formal specifications may describe recursive models which are difficult to identify so current assertion checkers limit, in a considerable way, the expressivity of the assertion language. In this paper, we are interested in showing how transformational synthesis can help to execute “expressive” assertions of the form ∀x(r(x) ⇔ QyR(x, y)) where x is a set of variables to be instantiated at execution time, Q is an existential or universal quantifier and R a quantifier free formula in the language of a particular first-order theory A we call assertion context. The class of assertion contexts is interesting because it presents a balance between expressiveness for writing assertions and existence of effective methods for executing them by means of synthesized (definite) logic programs

Molecular line intensities as measures of cloud masses - II. Conversion factors for specific galaxy types

We present theoretically-established values of the CO-to-H2 and C-to-H2 conversion factors that may be used to estimate the gas masses of external galaxies. We consider four distinct galaxy types, represented by M51, NGC 6946, M82 and SMC N27. The physical parameters that best represent the conditions within the molecular clouds in each of the galaxy types are estimated using a chi^2 analysis of several observed atomic fine structure and CO rotational lines. This analysis is explored over a wide range of density, radiation field, extinction, and other relevant parameters. Using these estimated physical conditions in methods that we have previously established, CO-to-H2 conversion factors are then computed for CO transitions up to J=9-8. For the conventional CO(1-0) transition, the computed conversion factor varies significantly below and above the canonical value for the Milky Way in the four galaxy types considered. Since atomic carbon emission is now frequently used as a probe of external galaxies, we also present, for the first time, the C-to-H2 conversion factor for this emission in the four galaxy types considered.Comment: 14 pages, 11 figures, accepted for publication in MNRA

Burmese amber fossils bridge the gap in the Cretaceous record of polypod ferns

publisher: Elsevier articletitle: Burmese amber fossils bridge the gap in the Cretaceous record of polypod ferns journaltitle: Perspectives in Plant Ecology, Evolution and Systematics articlelink: http://dx.doi.org/10.1016/j.ppees.2016.01.003 content_type: article copyright: Copyright © 2016 Elsevier GmbH. All rights reserved.Copyright © 2016 Elsevier GmbH. All rights reserved. This document is the authors' final accepted version of the journal article. You are advised to consult the publisher's version if you wish to cite from it

Is the ocean surface a source of nitrous acid (HONO) in the marine boundary layer?

Nitrous acid, HONO, is a key net photolytic precursor to OH radicals in the atmospheric boundary layer. As OH is the dominant atmospheric oxidant, driving the removal of many primary pollutants and the formation of secondary species, a quantitative understanding of HONO sources is important to predict atmospheric oxidising capacity. While a number of HONO formation mechanisms have been identified, recent work has ascribed significant importance to the dark, ocean-surface-mediated conversion of NO2 to HONO in the coastal marine boundary layer. In order to evaluate the role of this mechanism, here we analyse measurements of HONO and related species obtained at two contrasting coastal locations - Cabo Verde (Atlantic Ocean, denoted Cape Verde herein), representative of the clean remote tropical marine boundary layer, and Weybourne (UK), representative of semi-polluted northern European coastal waters. As expected, higher average concentrations of HONO (70ppt) were observed in marine air for the more anthropogenically influenced Weybourne location compared to Cape Verde (HONO <5ppt). At both sites, the approximately constant HONO/NO2 ratio at night pointed to a low importance for the dark, ocean-surface-mediated conversion of NO2 into HONO, whereas the midday maximum in the HONO/NO2 ratios indicated significant contributions from photo-enhanced HONO formation mechanisms (or other sources). We obtained an upper limit to the rate coefficient of dark, ocean-surface HONO-to-NO2 conversion of CHONOCombining double low line0.0011ppbh-1 from the Cape Verde observations; this is a factor of 5 lower than the slowest rate reported previously. These results point to significant geographical variation in the predominant HONO formation mechanisms in marine environments and indicate that caution is required when extrapolating the importance of such mechanisms from individual study locations to assess regional and/or global impacts on oxidising capacity. As a significant fraction of atmospheric processing occurs in the marine boundary layer, particularly in the tropics, better constraint of the possible ocean surface source of HONO is important for a quantitative understanding of chemical processing of primary trace gases in the global atmospheric boundary layer and associated impacts upon air pollution and climate

Open Questions in GRB Physics

Open questions in GRB physics are summarized as of 2011, including classification, progenitor, central engine, ejecta composition, energy dissipation and particle acceleration mechanism, radiation mechanism, long term engine activity, external shock afterglow physics, origin of high energy emission, and cosmological setting. Prospects of addressing some of these problems with the upcoming Chinese-French GRB mission, SVOM, are outlined.Comment: 27 pages. To appear in a special issue of Comptes Rendus Physique "GRB studies in the SVOM era", Eds. F. Daigne, G. Dubu

Potential future dynamics of carbon fluxes and pools in New England forests and their climatic sensitivities: A model-based study

Projections of terrestrial carbon (C) dynamics must account for interannual variation in ecosystem C exchange associated with climate change, increasing atmospheric CO2 concentration, and species dynamics. We used a dynamic ecosystem model to (i) project the potential dynamics of C in New England forests under nine climate change scenarios (CCSs) for the 21st century and (ii) examine the sensitivity of potential C dynamics to changes in climate and atmospheric CO2 concentration. Our results indicated that forest net primary productivity (NPP) and soil heterotrophic respiration (RH) averaged 428 and 279 gC/m2/yr and New England forests sequestered CO 2 by 149 gC/m2/yr in the baseline period (1971-2000). Under the nine future CCSs, NPP and RH were modeled to increase by an average rate of 0.85 and 0.56 gC/m2/yr2 during 1971-2099. The asymmetric increase in NPP and RH resulted in New England forests sequestering atmospheric CO2 at a net rate of 0.29 gC/m2/yr2 with increases in vegetation and soil C. Simulations also indicated that climate warming alone decreases NPP, resulting in a net efflux of C from forests. In contrast, increasing precipitation by itself stimulates CO 2 sequestration by forests. At the individual cell level, however, changes in temperature or precipitation can either positively or negatively affect consequent C dynamics. Elevation of CO2 levels was found to be the biggest driver for modeled future enhancement of C sequestration. Without the elevation of CO2 levels, climate warming has the potential to change New England forests from C sinks to sources in the late 21st century. ©2014. American Geophysical Union. All Rights Reserved

Colour reconnection in e+e- -> W+W- at sqrt(s) = 189 - 209 GeV

The effects of the final state interaction phenomenon known as colour reconnection are investigated at centre-of-mass energies in the range sqrt(s) ~ 189-209 GeV using the OPAL detector at LEP. Colour reconnection is expected to affect observables based on charged particles in hadronic decays of W+W-. Measurements of inclusive charged particle multiplicities, and of their angular distribution with respect to the four jet axes of the events, are used to test models of colour reconnection. The data are found to exclude extreme scenarios of the Sjostrand-Khoze Type I (SK-I) model and are compatible with other models, both with and without colour reconnection effects. In the context of the SK-I model, the best agreement with data is obtained for a reconnection probability of 37%. Assuming no colour reconnection, the charged particle multiplicity in hadronically decaying W bosons is measured to be (nqqch) = 19.38+-0.05(stat.)+-0.08 (syst.).Comment: 30 pages, 9 figures, Submitted to Euro. Phys. J.