Spatial distribution and galactic model parameters of cataclysmic variables

The spatial distribution, galactic model parameters and luminosity function of cataclysmic variables (CVs) in the solar neighbourhood have been determined from a carefully established sample of 459 CVs. The sample contains all of the CVs with distances computed from the Period-Luminosity-Colours (PLCs) relation of CVs which has been recently derived and calibrated with {\em 2MASS} photometric data. It has been found that an exponential function fits best to the observational z-distributions of all of the CVs in the sample, non-magnetic CVs and dwarf novae, while the sech^{2} function is more appropriate for nova-like stars and polars. The vertical scaleheight of CVs is 158$\pm$14 pc for the {\em 2MASS} J-band limiting apparent magnitude of 15.8. On the other hand, the vertical scaleheights are 128$\pm$20 and 160$\pm$5 pc for dwarf novae and nova-like stars, respectively. The local space density of CVs is found to be $\sim3\times10^{-5}$ pc^{-3} which is in agreement with the lower limit of the theoretical predictions. The luminosity function of CVs shows an increasing trend toward higher space densities at low luminosities, implying that the number of short-period systems should be high. The discrepancies between the theoretical and observational population studies of CVs will almost disappear if for the z-dependence of the space density the sech^{2} density function is used.Comment: 29 pages, 9 figures and 5 tables, accepted for publication in New Astronom

Metallicity Calibration and Photometric Parallax Estimation: I. UBV photometry

We present metallicity and photometric parallax calibrations for the F and G type dwarfs with photometric, astrometric and spectroscopic data. The sample consists of 168 dwarf stars covering the colour, iron abundance and absolute magnitude intervals $0.30<(B-V)_0<0.68$ mag, $-2.0<[Fe/H]<0.4$ dex and $3.4<M_V<6.0$ mag, respectively. The means and standard deviations of the metallicity and absolute magnitude residuals are small, i.e. $\langle\Delta[Fe/H]_{res}\rangle=0$ and $\sigma=0.134$ dex, and $\langle\Delta (M_V)_{res}\rangle=0$ and $\sigma=0.174$ mag, respectively, which indicate accurate metallicity and photometric parallax estimations.Comment: 13 pages, 11 figures and 2 tables, accepted for publication in Astrophysics and Space Scienc

Local Stellar Kinematics from RAVE data - VII. Metallicity Gradients from Red Clump Stars

We investigate the Milky Way Galaxy's radial and vertical metallicity gradients using a sample of 47,406 red clump stars from the RAVE DR4. This sample is more than twice the size of the largest sample in the literature investigating radial and vertical metallicity gradients. The absolute magnitude of Groenewegen (2008) is used to determine distances to our sample stars. The resulting distances agree with the RAVE DR4 distances Binney et al. (2014) of the same stars. Our photometric method also provides distances to 6185 stars that are not assigned a distance in RAVE DR4. The metallicity gradients are calculated with their current orbital positions ($R_{gc}$ and $Z$) and with their orbital properties (mean Galactocentric distance, $R_{m}$ and $z_{max}$), as a function of the distance to the Galactic plane: d[Fe/H]/d$R_{gc}=$-$0.047\pm0.003$ dex/kpc for $0\leq |Z|\leq0.5$ kpc and d[Fe/H]/d$R_m=$-$0.025\pm0.002$ dex/kpc for $0\leq z_{max}\leq0.5$ kpc. This reaffirms the radial metallicity gradient in the thin disc but highlights that gradients are sensitive to the selection effects caused by the difference between $R_{gc}$ and $R_{m}$. The radial gradient is flat in the distance interval 0.5-1 kpc from the plane and then becomes positive greater than 1 kpc from the plane. The radial metallicity gradients are also eccentricity dependent. We showed that d[Fe/H]/d$R_m=$-$0.089\pm0.010$, -$0.073\pm0.007$, -$0.053\pm0.004$ and -$0.044\pm0.002$ dex/kpc for $e_p\leq0.05$, $e_p\leq0.07$, $e_p\leq0.10$ and $e_p\leq0.20$ sub-samples, respectively, in the distance interval $0\leq z_{max}\leq0.5$ kpc. Similar trend is found for vertical metallicity gradients. Both the radial and vertical metallicity gradients are found to become shallower as the eccentricity of the sample increases. These findings can be used to constrain different formation scenarios of the thick and thin discs.Comment: 18 pages, including 16 figures and 6 tables, accepted for publication in PAS

Undifferentiated Carcinoma of Larynx of Nasopharyngeal Type

Undifferentiated carcinoma of nasopharyngeal type arising in the larynx is unusual. This type of carcinoma-which occurs almost exclusively in nasopharynx-is very infrequent in the larynx (0.2%). Till date only 17 cases are reported in the medical literature. We present the clinical and histopathological findings along with the management of one additional case of undifferentiated carcinoma of nasopharyngeal type in the larynx which was managed successfully with radiotherapy

Assessment of maximum inspiratory pressure: Prior submaximal respiratory muscle activity (‘warm-up’) enhances maximum inspiratory activity and attenuates the learning effect of repeated measurement

The official published version can be obtained from the link belowBackground: The variability of maximal inspiratory pressure (PImax) in response to repeated measurement affects its reliability; published studies have used between three and twenty PImax measurements on a single occasion. Objective: This study investigated the influence of a specific respiratory ‘warm-up’ upon the repeated measurement of inspiratory muscle strength and attempts to establish a procedure by which PImax can be assessed with maximum reliability using the smallest number of manoeuvres. Methods: Fourteen healthy subjects, familiar with the Mueller manoeuvre, were studied. The influence of repeated testing on a single occasion was assessed using an 18-measurement protocol. Using a randomised cross-over design, subjects performed the protocol, preceded by a specific respiratory warm-up (RWU) and on another occasion, without any preliminary activity (control). Comparisons were made amongst ‘baseline’ (best of the first 3 measurements), ‘short’ series (best of 7th to 9th measurement) and ‘long’ series (best of the last 3 measurements). Results: Under control conditions, the mean increase (‘baseline’ vs. ‘long’ series) was 11.4 (5.8)%; following the RWU, the increase (post RWU ‘baseline’ vs. ‘long’ series) was 3.2 (10.0)%. There were statistically significant differences between measurements made at all 3 protocol stages (‘baseline’, ‘short’ and ‘long’ series) under control conditions, but none following the RWU. Conclusions: The present data suggest that a specific RWU may attenuate the ‘learning effect’ during repeated PImax measurements, which is one of the main contributors of the test variability. The use of a RWU may provide a means of obtaining reliable values of PImax following just 3 measurements.This work was partially supported by a grant from the University of Wolverhampton, UK