OMEGA navigation system status and future plans

OMEGA is described as a very low frequency (VLF) radio navigational system operating in the internationally allocated navigation band in the electromagentic spectrum between 10 and 14 kilohertz. Full system implementation with worldwide coverage from eight transmitting stations is planned for the latter 1970's. Experimental stations have operated since 1966 in support of system evaluation and test. These stations provided coverage over most of the North Atlantic, North American Continent, and eastern portions of the North Pacific. This coverage provided the fundamental basis for further development of the system and has been essential to the demonstrated feasibility of the one to two nautical mile root-mean-square system accuracy. OMEGA is available to users in all nations, both on ships and in aircraft

Expansion-induced contribution to the precession of binary orbits

We point out the existence of new effects of global spacetime expansion on local binary systems. In addition to a possible change of orbital size, there is a contribution to the precession of elliptic orbits, to be added to the well-known general relativistic effect in static spacetimes, and the eccentricity can change. Our model calculations are done using geodesics in a McVittie metric, representing a localized system in an asymptotically Robertson-Walker spacetime; we give a few numerical estimates for that case, and indicate ways in which the model should be improved.Comment: revtex, 7 pages, no figures; revised for publication in Classical and Quantum Gravity, with minor changes in response to referees' comment

Ordering Policy Rules with an Unconditional Welfare Measure

The unconditional expectation of social welfare is often used to assess alternative macroeconomic policy rules in applied quantitative research. This paper provides a detailed analysis of such policies. It sets out the unconditionally optimal (UO) policy problem and derives a linear-quadratic (LQ) version of that problem that approximates the exact non-linear problem. The properties of UO policies are analyzed through a series of examples and contrasted with the timeless perspective (TP), exposited in Benigno and Woodford (2012). Some substantive implications for optimal monetary policy are explored

On the time dependent Schwarzschild - de Sitter spacetime

An imperfect cosmic fluid with energy flux is analyzed. Even though its energy density $\rho$ is positive, the pressure $p = -\rho$ due to the fact that the metric is asymptotically de Sitter. The kinematical quantities for a nongeodesic congruence are computed. The scalar expansion is time independent but divergent at the singularity $r = 2m$. Far from the central mass $m$ and for a cosmic time $\bar{t} << H^{-1}$, the heat flux $q$ does not depend on Newton's constant $G$.Comment: 8 pages, no figures, Sections 3 and 5 enlarged, one reference adde

Are Q-stars a serious threat for stellar-mass black hole candidates?

We examine the status of the threat posed to stellar-mass black hole candidates by the possible existence of Q-stars (compact objects with an exotic equation of state which might have masses well above the normally-accepted maximum for standard neutron stars). We point out that Q-stars could be extremely compact (with radii less than 1.5 times the corresponding Schwarzschild radius) making it quite difficult to determine observationally that a given object is a black hole rather than a Q-star, unless there is direct evidence for the absence of a solid surface. On the other hand, in order for a Q-star to have a mass as high as that inferred for the widely-favoured black hole candidate V404 Cygni, it would be necessary for the Q-matter equation of state to apply already at densities an order of magnitude below that of nuclear matter and this might well be considered implausible on physical grounds. We also describe how rotation affects the situation and discuss the prospects for determining observationally that black hole candidates are not Q-stars.Comment: 4 pages Latex, 5 figures, to appear in MNRA

ACTIVATION OF GABAA RECEPTORS AND INHIBITION OF NEUROSTEROID SYNTHESIS HAVE SEPARABLE ESTROUS-DEPENDENT EFFECTS ON BINGE DRINKING IN FEMALE MICE

poster abstractAlcohol concentrations relevant to the beginning stages of binge intoxica-tion may selectively activate GABAA receptor subtypes expressing δ-subunit proteins (δ-GABAAR). Indeed, administration of agonists that interact with these δ-GABAAR prior to alcohol access, can abolish binge drinking behavior (Melon and Boehm, 2011). Unfortunately, our ability to manipulate binge drinking in females is dependent upon estrous phase. The present experi-ments were designed to clarify the estrous-dependent effects of activation of δ-GABAAR on binge drinking. Specifically, we were interested in demonstrat-ing whether females display more persistent binge drinking as a function of cycle-dependent changes in the synthesis of endogenous neurosteroids that modulate δ-GABAAR. Using the Drinking-in-the-Dark binge-drinking model, regularly cycling female mice were given 2 hours of daily access to alcohol (20%v/v). Vaginal cytology was assessed after each drinking session to track estrous status. In experiment 1, animals were administered gaboxadol (an agonist with high affinity for δ-GABAAR) prior to their 8th day of access. In experiment 2, these methods were repeated, but mice received vehicle or finasteride (a neurosteroid synthesis inhibitor) 22hr prior to their 8th day of access. Results from experiment 1 demonstrated that diestrus females were insensitive to the significant gaboxadol-induced decrease in binge drinking observed for proestrus, estrus and metestrus females. In experiment 2, ve-hicle and finasteride treated diestrus females exhibited gaboxadol-induced reduction of their binge drinking. Surprisingly, finasteride pretreatment sig-nificantly reduced binge drinking for estrus females. These studies suggest that ovarian-linked changes to extrasynaptic GABAA R and to neurosteroid activity may be important factors in the binge consumption of alcohol for females. Future studies will further explore the role that acute stress during diestrus may play in inhibiting the effects of δ-GABAA R activation on binge drinking

High-Throughput Screening of the Asymmetric Decarboxylative Alkylation Reaction of Enolate-Stabilized Enol Carbonates

The use of high-throughput screening allowed for the optimization of reaction conditions for the palladium-catalyzed asymmetric decarboxylative alkylation reaction of enolate-stabilized enol carbonates. Changing to a nonpolar reaction solvent and to an electron-deficient PHOX derivative as ligand from our standard ­reaction conditions improved the enantioselectivity for the alkylation of a ketal-protected,1,3-diketone-derived enol carbonate from 28% ee to 84% ee. Similar improvements in enantioselectivity were seen for a β-keto ester derived and an α-phenyl cyclohexanone-­derived enol carbonate

Patient reactions to a web-based cardiovascular risk calculator in type 2 diabetes: a qualitative study in primary care.

Use of risk calculators for specific diseases is increasing, with an underlying assumption that they promote risk reduction as users become better informed and motivated to take preventive action. Empirical data to support this are, however, sparse and contradictory

Introduction of Multipurpose Tree Species for Improving the Productivity of Grasslands in the Tropics

To improve the productivity of the Sahelian pastures, 10 different tree species were introduced and cattle, sheep and goats were allowed to graze. After a year of establishment, survival rate of different species ranged from 6% to 68%. Acacia senegal, Acacia seyal, Acacia nilotica, Combretum aculeata and Prosopis cineraria performed well and the impact of browsing by goats was severe