Connection between dense gas mass fraction, turbulence driving, and star formation efficiency of molecular clouds

We examine the physical parameters that affect the accumulation of gas in molecular clouds to high column densities where the formation of stars takes place. In particular, we analyze the dense gas mass fraction (DGMF) in a set of self-gravitating, isothermal, magnetohydrodynamic turbulence simulations including sink particles to model star formation. We find that the simulations predict close to exponential DGMFs over the column density range N(H2) = 3-25 x 10^{21} cm^{-2} that can be easily probed via, e.g., dust extinction measurements. The exponential slopes correlate with the type of turbulence driving and also with the star formation efficiency. They are almost uncorrelated with the sonic Mach number and magnetic-field strength. The slopes at early stages of cloud evolution are steeper than at the later stages. A comparison of these predictions with observations shows that only simulations with relatively non-compressive driving (b ~< 0.4) agree with the DGMFs of nearby molecular clouds. Massive infrared dark clouds can show DGMFs that are in agreement with more compressive driving. The DGMFs of molecular clouds can be significantly affected by how compressive the turbulence is on average. Variations in the level of compression can cause scatter to the DGMF slopes, and some variation is indeed necessary to explain the spread of the observed DGMF slopes. The observed DGMF slopes can also be affected by the clouds' star formation activities and statistical cloud-to-cloud variations.Comment: 7 pages, 7 figures, accepted to A&A Letter

Natur und Freiheit im Perfektionismus. Zum Verständnis der Natur des Menschen in progressiven Traditionen

The paper argues that for a full-blown perfectionist theory to rely on liberal individualism and an ethics of sociality is not enough. In order to be consistent, an objective theory of the human good also needs to take human nature into account. In a first step this is shown by an analysis of George Sher′s important book, where human nature is lost underway (contrary to its central role in the main argument). A second step traces a viable theory of human nature in the progressive tradition of both radical enlightenment (esp. Condorcet) and American progressivism (esp. Dewey). It is argued that this theory can be defended against postmodern criticism and carries a strong egalitarian curren

A characterization of trees with equal 2-domination and 2-independence numbers

A set $S$ of vertices in a graph $G$ is a $2$-dominating set if every vertex of $G$ not in $S$ is adjacent to at least two vertices in $S$, and $S$ is a $2$-independent set if every vertex in $S$ is adjacent to at most one vertex of $S$. The $2$-domination number $\gamma_2(G)$ is the minimum cardinality of a $2$-dominating set in $G$, and the $2$-independence number $\alpha_2(G)$ is the maximum cardinality of a $2$-independent set in $G$. Chellali and Meddah [{\it Trees with equal $2$-domination and $2$-independence numbers,} Discussiones Mathematicae Graph Theory 32 (2012), 263--270] provided a constructive characterization of trees with equal $2$-domination and $2$-independence numbers. Their characterization is in terms of global properties of a tree, and involves properties of minimum $2$-dominating and maximum $2$-independent sets in the tree at each stage of the construction. We provide a constructive characterization that relies only on local properties of the tree at each stage of the construction.Comment: 17 pages, 4 figure

Perfektionismus und liberaler Egalitarismus. Ein Versuch ihrer Vermittlung

Perfectionism is a new player in the field of political philosophy. It is often rejected by liberal philosophers for it seems to have a conservative or paternalist bias. However, this paper argues first that perfectionism can have different political tendencies: it can be both liberal and illiberal, equalizing or anti-egalitarian, and be based on both limited or open conceptions of human nature. So perfectionism is not intrinsically conservative. Secondly, the paper aims to show that a strong case can be made for a liberal and egalitarian perfectionism, based on a rereading of Karl Marx. From this perspective it is not only unnecessary to criticize perfectionism from a liberal or egalitarian perspective, perfectionism may also help in justifying liberal egalitarianism in a new wa

Reliability of Public Private Partnership Projects under Assumptions of Cash Flow Volatility

This paper focuses on dynamic financial modelling of recurring cash flow items in PPP projects in operating stage and on risks associated with the volatility of these cash flows. As we concentrate on so-called government-pays schemes, only cash-outflows are considered, such as operating costs, repairs and maintenance expenses, and administration costs, whereas the revenue side is considered to be not at risk. We show different approaches to modelling the uncertainty of recurring operating expenses and explain how to interpret the results. Our analysis is based on the mathematical framework of stochastic processes, which, in finance, are particularly used to describe price series evolutions in capital markets. We apply them to generate variable trajectories of operating costs and integrate them into a stochastic simulation of the financial model.

Naturalistic Values and Progressive Politics

The paper argues that Dewey’s ethics are based on a naturalistic theory of value. This unusual interpretation questions the anti-naturalist reading of Dewey in the wake of Richard Rorty and other neo-pragmatists. In order to defend this interpretation, I develop a genealogy of Dewey’s pragmatic naturalism: It has a ’father’ in the progressivist movement, and a ’sister’ in the Chicago Sociology. A closer look at Frank L. Ward, Albion Small, W. I. Thomas and Robert Park helps to reconstruct the political dynamics of the progressivist programme of naturalistic values. This contextualization may also correct some of the shortcomings of Dewey’s own version: Some pragmatic sociologists spelled out the noncomformist individualism more clearly than Dewey’s philosophy did. Finally I suggest that this approach is still relevant today

Private Schools in Germany: Attendance up, but Not Among the Children of Less Educated Parents

The percentage of children attending private school in Germany has increased sharply in recent years. According to data of the German Socio-Economic Panel (SOEP), 7% of all students now attend private school. The SOEP, which contains a range of household data, shows that the children of parents with a university entry degree ("Abitur") are more likely to attend private school than those with less educated parents. This trend has become more pronounced in recent years: between 1997 and 2007, the percentage of students with better-educated parents attending private school increased by 77%. By contrast, the corresponding increase for students with less-educated parents was only 12%. Multivariate analyses demonstrate that increasing selection in favor of better-educated groups is particularly evident at the secondary school level. At the primary school level, full-time employment of the mother and regional factors significantly increase the chances of private school attendance. Educational policy should focus on preventing children from better-educated groups from leaving the public school system. If competition among schools is to be encouraged as a matter of policy, efforts should also be made to ensure less educated families consider sending their children to private schools.Private schools, Selection

Model atmospheres of irradiated exoplanets: The influence of stellar parameters, metallicity, and the C/O ratio

Many parameters constraining the spectral appearance of exoplanets are still poorly understood. We therefore study the properties of irradiated exoplanet atmospheres over a wide parameter range including metallicity, C/O ratio and host spectral type. We calculate a grid of 1-d radiative-convective atmospheres and emission spectra. We perform the calculations with our new Pressure-Temperature Iterator and Spectral Emission Calculator for Planetary Atmospheres (PETIT) code, assuming chemical equilibrium. The atmospheric structures and spectra are made available online. We find that atmospheres of planets with C/O ratios $\sim$ 1 and $T_{\rm eff}$ $\gtrsim$ 1500 K can exhibit inversions due to heating by the alkalis because the main coolants CH$_4$, H$_2$O and HCN are depleted. Therefore, temperature inversions possibly occur without the presence of additional absorbers like TiO and VO. At low temperatures we find that the pressure level of the photosphere strongly influences whether the atmospheric opacity is dominated by either water (for low C/O) or methane (for high C/O), or both (regardless of the C/O). For hot, carbon-rich objects this pressure level governs whether the atmosphere is dominated by methane or HCN. Further we find that host stars of late spectral type lead to planetary atmospheres which have shallower, more isothermal temperature profiles. In agreement with prior work we find that for planets with $T_{\rm eff}$ $<$ 1750 K the transition between water or methane dominated spectra occurs at C/O $\sim$ 0.7, instead of $\sim$ 1, because condensation preferentially removes oxygen.Comment: 30 pages, 20 figures. Accepted for publication in Ap

Somatostatin Analogues in the Treatment of Neuroendocrine Tumors: Past, Present and Future

In recent decades, the incidence of neuroendocrine tumors (NETs) has steadily increased. Due to the slow-growing nature of these tumors and the lack of early symptoms, most cases are diagnosed at advanced stages, when curative treatment options are no longer available. Prognosis and survival of patients with NETs are determined by the location of the primary lesion, biochemical functional status, differentiation, initial staging, and response to treatment. Somatostatin analogue (SSA) therapy has been a mainstay of antisecretory therapy in functioning neuroendocrine tumors, which cause various clinical symptoms depending on hormonal hypersecretion. Beyond symptomatic management, recent research demonstrates that SSAs exert antiproliferative effects and inhibit tumor growth via the somatostatin receptor 2 (SSTR2). Both the PROMID (placebo-controlled, prospective, randomized study in patients with metastatic neuroendocrine midgut tumors) and the CLARINET (controlled study of lanreotide antiproliferative response in neuroendocrine tumors) trial showed a statistically significant prolongation of time to progression/progression-free survival (TTP/PFS) upon SSA treatment, compared to placebo. Moreover, the combination of SSA with peptide receptor radionuclide therapy (PRRT) in small intestinal NETs has proven efficacy in the phase 3 neuroendocrine tumours therapy (NETTER 1) trial. PRRT is currently being tested for enteropancreatic NETs versus everolimus in the COMPETE trial, and the potential of SSTR-antagonists in PRRT is now being evaluated in early phase I/II clinical trials. This review provides a synopsis on the pharmacological development of SSAs and their use as antisecretory drugs. Moreover, this review highlights the clinical evidence of SSAs in monotherapy, and in combination with other treatment modalities, as applied to the antiproliferative management of neuroendocrine tumors with special attention to recent high-quality phase III trials