Fundamental properties of solar-like oscillating stars from frequencies of minimum Δν\Delta \nu : II. Model computations for different chemical compositions and mass

The large separations between the oscillation frequencies of solar-like stars are measures of stellar mean density. The separations have been thought to be mostly constant in the observed range of frequencies. However, detailed investigation shows that they are not constant, and their variations are not random but have very strong diagnostic potential for our understanding of stellar structure and evolution. In this regard, frequencies of the minimum large separation are very useful tools. From these frequencies, in addition to the large separation and frequency of maximum amplitude, Y\i ld\i z et al. recently have developed new methods to find almost all the fundamental stellar properties. In the present study, we aim to find metallicity and helium abundances from the frequencies, and generalize the relations given by Y\i ld\i z et al. for a wider stellar mass range and arbitrary metallicity ($Z$) and helium abundance ($Y$). We show that the effect of metallicity is { significant} for most of the fundamental parameters. For stellar mass, for example, the expression must be multiplied by (Z/Z_{\sun})^{0.12}. For arbitrary helium abundance, M \propto (Y/Y_{\sun})^{0.25} . Methods for determination of $Z$ and $Y$ from pure asteroseismic quantities are based on amplitudes (differences between maximum and minimum values of \Dnu) in the oscillatory component in the spacing of oscillation frequencies. Additionally, we demonstrate that the difference between the first maximum and the second minimum is very sensitive to $Z$. It also depends on $\nu_{\rm min1}/\nu_{\rm max}$ and small separation between the frequencies. Such a dependence leads us to develop a method to find $Z$ (and $Y$) from oscillation frequencies. The maximum difference between the estimated and model $Z$ values is about 14 per cent. It is 10 per cent for $Y$.Comment: 8 pages, 13 figures; published in MNRAS (2015

On the structure and evolution of planets and their host stars −- effects of various heating mechanisms on the size of giant gas planets

It is already stated in the previous studies that the radius of the giant planets is affected by stellar irradiation. The confirmed relation between radius and incident flux depends on planetary mass intervals. In this study, we show that there is a single relation between radius and irradiated energy per gram per second ($l_-$), for all mass intervals. There is an extra increase in radius of planets if $l_-$ is higher than 1100 times energy received by the Earth ($l_\oplus$). This is likely due to dissociation of molecules. The tidal interaction as a heating mechanism is also considered and found that its maximum effect on the inflation of planets is about 15 per cent. We also compute age and heavy element abundances from the properties of host stars, given in the TEPCat catalogue (Southworth 2011). The metallicity given in the literature is as [Fe/H]. However, the most abundant element is oxygen, and there is a reverse relation between the observed abundances [Fe/H] and [O/Fe]. Therefore, we first compute [O/H] from [Fe/H] by using observed abundances, and then find heavy element abundance from [O/H]. We also develop a new method for age determination. Using the ages we find, we analyse variation of both radius and mass of the planets with respect to time, and estimate the initial mass of the planets from the relation we derive for the first time. According to our results, the highly irradiated gas giants lose 5 per cent of their mass in every 1 Gyr.Comment: 15 pages, 13 figures, 3 tables. Accepted by MNRA

Crystal structure of rac-3-hydroxy-2-(p-tolyl)-2,3,3a,4,7,7a-hexahydro-1H-4,7-methanoisoindol-1-one

In the title compound, C16H17NO2, the cyclohexene ring adopts a boat conformation, and the five-membered rings have envelope conformations with the bridging atom as the flap. Their mean planes are oriented at a dihedral angle of 86.51 (7)°. The molecular structure is stabilized by a short intramolecular C - H⋯O contact. In the crystal, molecules are linked by O - H⋯O hydrogen bonds forming chains propagating along [100]. The chains are linked by C - H⋯π interactions, forming slabs parallel to (001)

Asteroseismic Investigation of 20 Planet and Planet-Candidate Host Stars

Planets and planet candidates are subjected to great investigation in recent years. In this study, we analyse 20 planet and planet-candidate host stars at different evolutionary phases. We construct stellar interior models of the host stars with the MESA evolution code and obtain their fundamental parameters under influence of observational asteroseismic and non-asteroseismic constraints. Model mass range of the host stars is 0.74-1.55 ${\rm M}_\odot$. The mean value of the so-called large separation between oscillation frequencies and its variation about the minima show the diagnostic potential of asteroseismic properties. Comparison of variations of model and observed large separations versus the oscillation frequencies leads to inference of fundamental parameters of the host stars. Using these parameters, we revise orbital and fundamental parameters of 34 planets and four planet candidates. According to our findings, radius range of the planets is 0.35-16.50 $\mathrm{R}_{\oplus}$. The maximum difference between the transit and revised radii occurs for Kepler-444b-f is about 25 per cent.Comment: 9 pages, 7 figures, 6 table

h-deformation of Gr(2)

The $h$-deformation of functions on the Grassmann matrix group $Gr(2)$ is presented via a contraction of $Gr_q(2)$. As an interesting point, we have seen that, in the case of the $h$-deformation, both R-matrices of $GL_h(2)$ and $Gr_h(2)$ are the same

Critical Dialog: Response to Rachel M. Gillum’s Review of The Politics of the Headscarf in the United States

A Critical Dialog between the reviewer, Rachel M. Gillum, of The Politics of the Headscarf in the United States and the authors, Bozena C. Welborne, Aubrey L. Westfall, Özge Çelik Russell, and Sarah A. Tobin. Ithaca: Cornell University Press, 2018. 264p

Powering performance prediction of a semi-displacement ship retrofitted with Hull Vane

This study predicts the powering performance of a semi-displacement ship, both without and with a Hull Vane (HV). HV is an energy-saving appendage fixed at the transom bottom of the ship's hull. Although the HV is commercially known as a successful resistance-reducing device, there are no studies in the literature examining its effect on propulsion performance in detail. In this study, the effect of the HV on the propulsion performance is investigated and a practical method is proposed as an engineering application to reduce the computation time. Initially, the idealized disc model based on Blade Element Theory (BET) is preferred to create a thrust force instead of using an entire physical propeller. The dynamic motions of the ship are reflected in the computational analysis. Subsequently, the sliding mesh technique, which models the exact propeller geometry, is implemented to calculate the self-propulsion characteristics without and with HV. These computations are achieved by employing a two-phase flow solver available in OpenFOAM. This study provides a significant demonstration to clarify the effect of HV on powering performance. It not only decreases effective power by 11.41% but also increases the propulsive efficiency by 2.1%, which reduces the brake power by 14.61% in total at service speed

When bladder and brain collide: Is there a gender difference in the relationship between urinary incontinence, chronic depression, and anxiety?

In longitudinal and cross-sectional studies, depression and anxiety have been associated with urinary incontinence (UI) in women. However, this association has not been studied in men. Utilizing data from the 2008 Turkish Health Studies Survey conducted by the Turkish Statistical Institute, we analyzed 13,830 participants aged 15 years and above. We investigated the association of UI with psychological discomfort in both sexes using multivariable logistic regression. High psychological discomfort significantly correlated with UI in males (OR 2.30, 95% CI 1.43–3.71) and females (OR 2.78, 95% CI 1.80–4.29). Anxiety increased UI likelihood in females (OR 2.36, 95% CI 1.61–3.46) and males (OR 2.37, 95% CI 1.10–5.13). Depression related significantly to UI in females (OR 2.54, 95% CI 1.81–3.58) but not males (OR 1.63, 95% CI 0.71–3.76). Antidepressant and anxiolytic use was not significantly related to UI in either gender. Anxiety and psychological discomfort contribute to UI in both genders. While depression significantly correlates with UI in females, it does not show the same magnitude and significance in males. Antidepressant and anxiolytic use did not significantly influence the association. These findings underscore the psychological distress-UI link, advocating a holistic approach for managing UI in individuals with mental health conditions

Fundamental properties of Kepler and CoRoT targets -- IV. Masses and radii from frequencies of minimum Δν\Delta {\nu} and their implications

Recently, by analysing the oscillation frequencies of 90 stars, Yildiz, \c{C}elik Orhan & Kayhan have shown that the reference frequencies ($\nu_{\rm min0}$, $\nu_{\rm min1}$ and $\nu_{\rm min2}$) derived from glitches due to He {\scriptsize II} ionization zone have very strong diagnostic potential for the determination of their effective temperatures. In this study, we continue to analyse the same stars and compute their mass, radius and age from different scaling relations including relations based on $\nu_{\rm min0}$, $\nu_{\rm min1}$ and $\nu_{\rm min2}$. For most of the stars, the masses computed using $\nu_{\rm min0}$ and $\nu_{\rm min1}$ are very close to each other. For 38 stars, the difference between these masses is less than 0.024 ${\rm M}_\odot$. The radii of these stars from $\nu_{\rm min0}$ and $\nu_{\rm min1}$ are even closer, with differences of less than 0.007 ${\rm R}_\odot$. These stars may be the most well known solar-like oscillating stars and deserve to be studied in detail. The asteroseismic expressions we derive for mass and radius show slight dependence on metallicity. We therefore develop a new method for computing initial metallicity from this surface metallicity by taking into account the effect of microscopic diffusion. The time dependence of initial metallicity shows some very interesting features that may be important for our understanding of chemical enrichment of Galactic Disc. According to our findings, every epoch of the disc has its own lowest and highest values for metallicity. It seems that rotational velocity is inversely proportional to 1/2 power of age as given by the Skumanich relation.Comment: 19 pages, 12 figure