Bounds on M/R for static objects with a positive cosmological constant

We consider spherically symmetric static solutions of the Einstein equations with a positive cosmological constant $\Lambda,$ which are regular at the centre, and we investigate the influence of $\Lambda$ on the bound of M/R, where M is the ADM mass and R is the area radius of the boundary of the static object. We find that for any solution which satisfies the energy condition $p+2p_{\perp}\leq\rho,$ where $p\geq 0$ and $p_{\perp}$ are the radial and tangential pressures respectively, and $\rho\geq 0$ is the energy density, and for which $0\leq \Lambda R^2\leq 1,$ the inequality \frac{M}{R}\leq\frac29-\frac{\Lambda R^2}{3}+\frac29 \sqrt{1+3\Lambda R^2}, holds. If $\Lambda=0$ it is known that infinitely thin shell solutions uniquely saturate the inequality, i.e. the inequality is sharp in that case. The situation is quite different if $\Lambda>0.$ Indeed, we show that infinitely thin shell solutions do not generally saturate the inequality except in the two degenerate situations $\Lambda R^2=0$ and $\Lambda R^2=1$. In the latter situation there is also a constant density solution, where the exterior spacetime is the Nariai solution, which saturates the inequality, hence, the saturating solution is non-unique. In this case the cosmological horizon and the black hole horizon coincide. This is analogous to the charged situation where there is numerical evidence that uniqueness of the saturating solution is lost when the inner and outer horizons of the Reissner-Nordstr\"{o}m solution coincide.Comment: 14 pages; Improvements and corrections, published versio

Differentiation of Burnout Syndrome by Profession and Job: Gazi Burnout Inventory

Defined as the situation individuals undergo in the face of stress, burnout syndrome appears to be a handicap not only conveying the feeling of isolation towards a specific job or profession but diminishing the productivity of individual in profession-related settings as well. This study sets out to develop and design an attitude scale in order to explore the differentiation of burnout of individuals in terms of job and profession concepts. In order to measure professional and job burnout, a trial scale was formed covering 106 statements obtained from 80 students with a job or profession at an MBA program and this scale was administered. Reliability and validity analyses of the Data obtained were performed and as the results of the analyses performed a 14-item professional burnout scale and a 12-item job burnout scale were developed.burnout, measurement, professional burnout, job burnout

DNA Demethylation in Pluripotency and Reprogramming: The Role of Tet Proteins and Cell Division

Cytosine methylation is found in the genomes of many plants and animals and has been associated with transcriptional silencing in mammals. At critical stages in embryo development, when cellular potential is reset, DNA methylation is lost in a series of “sequential waves.” The mechanism underlying this is controversial and complex. Several new reports now suggest that TET enzymes and cell division are important for these in vivo transitions as well as for experimentally induced reprogramming

Between Europeanism and Nativism: Exploring a Cleavage Model of European Public Sphere in Social Media

The European Union’s common public sphere project dates back to the 1960s and relies on Europeanisation through the gradual eradication of communication boundaries between its member countries. However, it is evident by now that Europeanisation of national public spheres is hard to achieve by increasing overlaps between national public spheres, synchronisation of news reporting across national boundaries, or diffusion of Europeanist norms into national politics. The European Union’s common public sphere project may hence be in danger. This calls for explorations of other imaginable models of the public sphere for Europe. Are there traces of other modes of transnational public sphere emerging in Europe? In this article, we explore a models of the transnational public sphere which is based on an alternative concept of Europeanisation derived from the cleavage theory. By drawing on social media data and employing tools of social network analysis, we demonstrate the empirical possibility of a cleavage model of the European public sphere.publishedVersio

Asylum seekers in the machinery of the state: administrative capacity vs. preferences. Recognition rates in EU member states

Studies have sought to explain variation in protection recognition rates between EU member states with, however, limited explanatory power. Surprisingly, few have contemplated the role of the administration, despite it being at the centre of the process through which asylum claims are examined. We posit that recognition rates are significantly affected by administrative capacity, although the administration's action may be mitigated by political factors. Our findings show that administrative effectiveness and experience in asylum matters yield higher recognition rates. We show that government preferences and the overall political context affect protection recognition, too. Importantly, we also find that the mechanisms at play are different if we consider the different forms of protection.publishedVersio

Interaction-induced mode switching in steady-state microlasers

We demonstrate that due to strong modal interactions through cross-gain saturation, the onset of a new lasing mode can switch off an existing mode via a negative power slope. In this process of interaction-induced mode switching (IMS) the two involved modes maintain their identities, i.e. they do not change their spatial field patterns or lasing frequencies. For a fixed pump profile, a simple analytic criterion for the occurrence of IMS is given in terms of their self- and cross-interaction coefficients and non-interacting thresholds, which is verified for the example of a two-dimensional microdisk laser. When the spatial pump profile is varied as the pump power is increased, IMS can be induced even when it would not occur with a fixed pump profile, as we show for two coupled laser cavities. Our findings apply to steady-state lasing and are hence different from dynamical mode switching or hopping. IMS may have potential applications in robust and flexible all-optical switching.Comment: 14 pages, 5 figure

Anomalous transient amplification of waves in non-normal photonic media

Dissipation is a ubiquitous phenomenon in dynamical systems encountered in nature because no finite system is fully isolated from its environment. In optical systems, a key challenge facing any technological application has traditionally been the mitigation of optical losses. Recent work has shown that a new class of optical materials that consist of a precisely balanced distribution of loss and gain can be exploited to engineer novel functionalities for propagating and filtering electromagnetic radiation. Here we show a generic property of optical systems that feature an unbalanced distribution of loss and gain, described by non-normal operators, namely that an overall lossy optical system can transiently amplify certain input signals by several orders of magnitude. We present a mathematical framework to analyze the dynamics of wave propagation in media with an arbitrary distribution of loss and gain and construct the initial conditions to engineer such non-normal power amplifiers. Our results point to a new design space for engineered optical systems employed in photonics and quantum optics.Comment: 11 pages, 11 figure

Energies and wave functions for a soft-core Coulomb potential

For the family of model soft Coulomb potentials represented by V(r) = -\frac{Z}{(r^q+\beta^q)^{\frac{1}{q}}}, with the parameters Z>0, \beta>0, q \ge 1, it is shown analytically that the potentials and eigenvalues, E_{\nu\ell}, are monotonic in each parameter. The potential envelope method is applied to obtain approximate analytic estimates in terms of the known exact spectra for pure power potentials. For the case q =1, the Asymptotic Iteration Method is used to find exact analytic results for the eigenvalues E_{\nu\ell} and corresponding wave functions, expressed in terms of Z and \beta. A proof is presented establishing the general concavity of the scaled electron density near the nucleus resulting from the truncated potentials for all q. Based on an analysis of extensive numerical calculations, it is conjectured that the crossing between the pair of states [(\nu,\ell),(\nu',\ell')], is given by the condition \nu'\geq (\nu+1) and \ell' \geq (\ell+3). The significance of these results for the interaction of an intense laser field with an atom is pointed out. Differences in the observed level-crossing effects between the soft potentials and the hydrogen atom confined inside an impenetrable sphere are discussed.Comment: 13 pages, 5 figures, title change, minor revision