A new Tolman test of a cosmic distance duality relation at 21 cm

Under certain general conditions in an expanding universe, the luminosity distance (d_L) and angular diameter distance (d_A) are connected by the Etherington relation as d_L = d_A (1 + z)^2. The Tolman test suggests the use of objects of known surface brightness, to test this relation. In this letter, we propose the use of redshifted 21 cm signal from disk galaxies, where neutral hydrogen (HI) masses are seen to be almost linearly correlated with surface area, to conduct a new Tolman test. We construct simulated catalogs of galaxies, with the observed size-luminosity relation and realistic redshift evolution of HI mass functions, likely to be detected with the planned Square Kilometer Array (SKA). We demonstrate that these observations may soon provide the best implementation of the Tolman test to detect any violation of the Etherington relation.Comment: 4 pages, 2 figures, 1 table, v2: published versio

Preferences of University Academic Staff for Their Surrounding Environment: Uludag University as a Case Study

As a result of the damage to natural areas, open and green spaces in cities shrink in area and even disappear. This has caused an increase in the number of studies concerned with human-nature relations in urban landscaping. Contrary to the fact that the major part of our lives is spent in our workplaces, there are not many studies that investigate human-nature relations in workspaces. However, workspaces cover big areas of the urban landscape, their arrangement is of major importance in both an ecological and economical sense. The present study aims to shed light on how the academic staffs working at the Uludag University campus perceive the nature that surrounds their workspace and what their expectations concerning their natural surroundings are. Although the employees wish to see arranged landscapes surrounding their workplace, they significantly prefer naturally arranged spaces. It is evident that the staffs are concerned about the surroundings of the buildings they work in and that they make correct assumptions about and descriptions of the surroundings of their buildings

The Effects of Planting Density on the Dry Matter Yield and the Overwintering Ability of the Dwarf and Normal Napiergrasses in Two Years after Planting

The objective of this study is to determine the optimum planting density in napiergrass (Pennisetum purpureum Schumach) among two dwarf varieties introduced from Thailand and two normal ones under three levels of density. Dwarf varieties showed lower plant height and mean tiller weight, and higher leaf area index (LAI) and leaf blade percentage. Crop growth rate was positively correlated with LAI, and net assimilation rate and canopy extinction coefficient (K) were negatively correlated with LAI in the second year, including all dwarf and normal varieties, while K tended to be lower in the dwarf varieties. With the increase in the planting density, dry matter yield tended to increase, the difference between the normal varieties and early-heading dwarf variety was reduced, and the over wintering ability in all varieties was decreased. It was concluded that late-heading dwarf and normal varieties should be planted at the medium density by a desirable combination of productivity and considerable over wintering ability

Bulk phantom fields, increasing warp factors and fermion localisation

A bulk phantom scalar field (with negative kinetic energy) in a sine--Gordon type potential is used to generate an exact thick brane solution with an increasing warp factor. It is shown that the growing nature of the warp factor allows the localisation of massive as well as massless spin-half fermions on the brane even without any additional non--gravitational interactions. The exact solutions for the localised massive fermionic modes are presented and discussed. The inclusion of a fermion--scalar Yukawa coupling appears to change the mass spectrum and wave functions of the localised fermion though it does not play the crucial role it did in the case of a decreasing warp factor.Comment: 11 pages, 3 figures, RevTex

Proton-electron mass ratio from HD+^+ revisited

We present a new derivation of the proton-electron mass ratio from the hydrogen molecular ion, HD$^+$. The derivation entails the adjustment of the mass ratio in highly precise theory so as to reproduce accurately measured ro-vibrational frequencies. This work is motivated by recent improvements of the theory, as well as the more accurate value of the electron mass in the recently published CODATA-14 set of fundamental constants, which justifies using it as input data in the adjustment, rather than the proton mass value as done in previous works. This leads to significantly different sensitivity coefficients and, consequently, a different value and larger uncertainty margin of the proton-electron mass ratio as obtained from HD$^+$

Cosmic optical activity from an inhomogeneous Kalb-Ramond field

The effects of introducing a harmonic spatial inhomogeneity into the Kalb-Ramond field, interacting with the Maxwell field according to a `string-inspired' proposal made in earlier work are investigated. We examine in particular the effects on the polarization of synchrotron radiation from cosmologically distant (i.e. of redshift greater than 2) galaxies, as well as the relation between the electric and magnetic components of the radiation field. The rotation of the polarization plane of linearly polarized radiation is seen to acquire an additional contribution proportional to the square of the frequency of the dual Kalb-Ramond axion wave, assuming that it is far smaller compared to the frequency of the radiation field.Comment: 9 pages, Revtex, no figure

Optimization Rules in DLV for the Bridge Crossing Problem

Disjunctive logic programming is a powerful tool in knowledge representation and commonsense reasoning. The first solid implementation of a DLP system is called DLV (Datalog with Vel). In this paper we offer three strategies to produce optimal solutions in DLV for the well-known Bridge Crossing Problem. These strategies are a piggyback strategy, a non-piggyback strategy, and a mixed strategy. An analysis to determine the number of time steps required for an optimal solution using these strategies is provided. We also characterize and prove the conditions under which a particular strategy should be used to obtain an optimal solution. These strategies are implemented in the form of optimization rules in a DLV program for the bridge crossing problem. Preliminary results indicate a drastic reduction in execution time when compared to other DLV programs for bridge crossing which do not incorporate these strategies. Our implementation uses a DLV Java wrapper, allowing us to embed disjunctive logic programs inside an object-oriented environment