Non-LTE radiative transfer in cool stars. Theory and applications to the abundance analysis for 24 chemical elements

The interpretation of observed spectra of stars in terms of fundamental stellar properties is a key problem in astrophysics. For FGK-type stars, the radiative transfer models are often computed using the assumption of local thermodynamic equilibrium (LTE). Its validity is often questionable and needs to be supported by detailed studies, which build upon the consistent framework of non-LTE. In this review, we outline the theory of non-LTE. The processes causing departures from LTE are introduced qualitatively by their physical interpretation, as well as quantitatively by their impact on the models of stellar spectra and element abundances. We also compile and analyse the most recent results from the literature. In particular, we examine the non-LTE effects for 24 chemical elements for six late-studied FGK-type stars.Comment: 19 pages, accepted for publication as a chapter in "Determination of Atmospheric Parameters of B, A, F and G Type Stars", Springer (2014), eds. E. Niemczura, B. Smalley, W. Pyc

Electron Wavefunctions and Densities for Atoms

With a special `Ansatz' we analyse the regularity properties of atomic electron wavefunctions and electron densities. In particular we prove an a priori estimate, $\sup_{y\in B(x,R)}|\nabla\psi(y)| \leq C(R) \sup_{y\in B(x,2R)}|\psi(y)|$ and obtain for the spherically averaged electron density, $\widetilde\rho(r)$, that $\widetilde\rho''(0)$ exists and is non-negative

Influence of Contraception Use on the Reproductive Health of Adolescents and Young Adults

Oral contraceptives (OCs) are often prescribed to adolescents and young adults for the treatment of health problems and to avoid unwanted pregnancies. We hypothesized that the use of OCs, among adolescents and young adults, is associated with a greater likelihood of pregnancy, abortion, sexually transmitted diseases (STDs), pelvic inflammatory disease (PID), and sexual behaviors that will enhance those problems (i.e., earlier sexual debut and more sexual partners) than adolescents and young adults not using OCs. To test this hypothesis, data from 1,365 adolescents and young adults in the 2011–2013 National Survey of Family Growth (NSFG) were used to describe the influence of ever use of OCs on ever having sex, sexual debut, multiple sexual partners, STDs, PID, pregnancy, and abortion. A secondary purpose was to evaluate protective factors from unhealthy sexual practices like religiosity, church attendance, and intact families. We found that the “ever use” of OCs by US adolescents and young adults results in a greater likelihood of ever having sex, STDs, PID, pregnancy, and abortion compared with those adolescents and young adults who never used OCs. Furthermore, those adolescents who ever used OCs had significantly more male sexual partners than those who never used OCs, and they also had an earlier sexual debut by almost two years. Conversely, we found that frequent church attendance, identification of the importance of religion, and having an intact family among adolescents were associated with less likelihood of unsafe sexual practices. We concluded that the use of OCs by adolescents and young adults might be considered a health risk. Further research is recommended to confirm these associations. Summary: The purpose of this article was to show the correlation between contraceptive use in adolescents and negative sexual outcomes. We used data from the 2011–2013 NSFG and demonstrated that never married adolescents who used oral hormonal contraception were three times more likely to have an STD, have PID, and to become pregnant, and, surprisingly, ten times more likely of having an abortion compared to noncontracepting adolescents. These are outcomes that contraception is intended to prevent. These data also showed that the contraceptors had significantly more male partners than their contraceptive counterparts. Protective factors such as church attendance and family cohesiveness were associated with a decreased likelihood of sexual activity

Generating Survival Times to Simulate Cox Proportional Hazards Models

This paper discusses techniques to generate survival times for simulation studies regarding Cox proportional hazards models. In linear regression models, the response variable is directly connected with the considered covariates, the regression coefficients and the simulated random errors. Thus, the response variable can be generated from the regression function, once the regression coefficients and the error distribution are specified. However, in the Cox model, which is formulated via the hazard function, the effect of the covariates have to be translated from the hazards to the survival times, because the usual software packages for estimation of Cox models require the individual survival time data. A general formula describing the relation between the hazard and the corresponding survival time of the Cox model is derived. It is shown how the exponential, the Weibull and the Gompertz distribution can be used to generate appropriate survival times for simulation studies. Additionally, the general relation between hazard and survival time can be used to develop own distributions for special situations and to handle flexibly parameterized proportional hazards models. The use of other distributions than the exponential distribution only is indispensable to investigate the characteristics of the Cox proportional hazards model, especially in non-standard situations, where the partial likelihood depends on the baseline hazard

What is Allium achaium Boiss. & Orph.? Disentangling the taxonomy of a Greek mountain species

Allium oreohellenicum Tzanoud., Tsakiri & Raus (Amaryllidaceae), endemic of the Greek mountains, is described and illustrated as a species new to science. Information regarding its cytology, geographical distribution and taxonomic relationships is also provided. Material belonging to A. oreohellenicum was formerly known/classified as A. achaium Boiss & Orph., a taxon described in 1882 based on a gathering by Orphanides from Mt Klokos (N Peloponnisos, Greece). A detailed study of the Orphanides gathering concerned revealed that it essentially belongs to A. frigidum Boiss. & Heldr., a taxon described 28 years earlier, and so the need for a new name

Yet another approach to the Gough-Stewart platform forward kinematics

© 20xx IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works.The forward kinematics of the Gough-Stewart platform, and their simplified versions in which some leg endpoints coalesce, has been typically solved using variable elimination methods. In this paper, we cast doubts on whether this is the easiest way to solve the problem. We will see how the indirect approach in which the length of some extra virtual legs is first computed leads to important simplifications. In particular, we provide a procedure to solve 30 out of 34 possible topologies for a Gough-Stewart platform without variable elimination.Peer ReviewedPostprint (author's final draft

Baseline Survey on Reproductive Health Needs in Preparation of a CBD Program in Lushoto Division,Lushoto District

\ud This community based household study was designed to collect baseline data on reproductive health Lushoto division of Lushoto District, selected as a pilot area for a community Based Distribution program. The study focused on main reproductive health indicators (fertility, fertility regulation, maternal health and on knowledge about sexually transmitted diseases). The study design originates from the MoH-GTZ project on reproductive health in Kenya where rapid assessment tool was adapted according to the needs of the field of reproductive health. 478 randomly selected women in reproductive age (15-49) from 6 villages were interviewed with a questionnaire. The main findings are: In Lushoto division the contraceptive prevalence is 29%. 77% of the study population know at least one modern method of family planning. Regarding provision of services 79% of women preferred women of their or any age 18% did not mind at all who offers the service. 86% of the women could at least name one STDs. Asked what they currently do not prevent themselves or their partner from being at risk for STDs 60% answered “nothing”. The percentage of institutional deliveries (in Health Centre, Dispensary or Hospital) was 22% however 98 % of the women had received antenatal care including tetanus vaccination. The survey revealed that 47% of the women had initiated to live with a male partner before attaining 19 years of age. The final conclusion is that there is a considerable unmet need for family planning services in Lushoto division. Out of those who do not want a pregnancy in the following years only 33% prevent pregnancy 30% with modern methods. \u