A compact fractal monopole planar antenna with size of 30× 25 mm 2 is proposed for ultra wide band (UWB) application. The proposed antenna is designed by combination of Giusepe Peano and Sierpinski Carpet fractal geometries. The feed circuit is a microstrip line with a matching section over a semi-elliptical ground plane. The proposed antenna has an omnidirectional radiation pattern and good gain. The simulated results of return loss, gain and radiation patterns are presented and discussed.
Short-orbital period small-eccentricity binary pulsars can, in principle, experience substantial advance of periastron. We explore the possibility of measuring this effect by implementing a timing model, ELL1k, in the popular TEMPO2 pulsar timing package. True secular variations in the Laplace-Lagrange parameters, present in our ELL1k model, can lead to measurable timing residuals while pursuing decade-long timing campaigns using the existing ELL1 timing model of Lange et al. (2001), especially for binaries exhibiting significant periastron advance. We also list the main differences between our approach and various implementations of the ELL1 model present in both TEMPO and TEMPO2 packages. Detailed TEMPO2 simulations suggest the possibility of constraining the apsidal motion constant of pulsar companions in certain observed binary pulsars with minuscule eccentricities such as PSR J1719−1438. Fortunately, the ELL1k timing model does not pose any challenges to the on-going Pulsar Timing Array campaigns that routinely employ the ELL1 timing model.
We present far ultraviolet (FUV) observations of globular cluster NGC 4147 using three FUV filters, BaF 2 (F154W), sapphire (F169M), and silica (F172M) of Ultra-Violet Imaging Telescope (UVIT) onboard the AstroSat satellite. We confirmed the cluster membership of the UVIT observed sources using proper motions from Gaia data release 2 (GAIA DR2). We identified 37 blue horizontal branch stars (BHBs), one blue straggler star (BSS) and 15 variable stars using UV-optical color magnitude diagrams (CMDs). We find that all the FUV bright BHBs are second generation population stars. Using UV-optical CMDs, we identify two sub-populations, BHB1 and BHB2, among the UV-bright BHBs in the cluster with stars count ratio of 24:13 for BHB1 and BHB2. The effective temperatures (T eff ) of BHB1 and BHB2 were derived using color-temperature relation of BaSTI-IAC zero-age horizontal branch (ZAHB). We found that BHB1 stars are more centrally concentrated than BHB2 stars. We also derive physical parameters of the detected FUV bright BSS by fitting younger age BaSTI-IAC isochrones on optical and UV-optical CMDs.
We present detailed photometric observations of the Galactic globular cluster NGC 7492 using the data obtained with two far-ultraviolet (FUV; 1300–1800 Å) and three near-ultraviolet (NUV; 2000–3000 Å) filters of Ultraviolet Imaging Telescope (UVIT) onboard the AstroSat satellite. We confirmed the cluster membership of the extracted sources using Gaia data release 2 (Gaia DR2) proper motion data. We have used colour–magnitude diagrams (CMDs) using UVIT and GAIA filters to separate out different evolutionary stages of the stars present in the cluster. We have identified a new extreme horizontal branch (EHB) star at the core of the cluster using UV and UV-optical CMDs. The estimated distance modulus of the cluster is 16.95 ± 0.05 obtained by fitting BaSTI isochrones with cluster parameters, [Fe/H] = −1.8 dex and age =12.0 Gyr on the V − I versus V CMD. Interestingly, only the EHB star and blue horizontal branch stars (BHBs) among the UV-bright hot sources are detected in FUV filters of UVIT. We have derived the effective temperature of BHBs using colour–temperature relation and spectral energy distributions (SEDs) of multiband filters, which are in the range from 8000 to 10 500 K. We find a variation of He abundance of BHBs by fitting the BaSTI ZAHB (zero-age horizontal branch). The range in the He abundance of the BHBs corresponding to the best-fitting isochrones is from 0.247 to 0.350. We have estimated various physical parameters of the newly identified EHB star in the cluster using SED fit and post-HB evolutionary tracks. We have studied the radial distribution of all the sources of the cluster detected in UVIT. The sources detected in FUV filters extend beyond the half-light radius (1.15 arcmin) of the cluster, whereas the sources detected in NUV filters extend beyond the tidal radius (9.2 arcmin) of the cluster.
In the era of rising multiple pregnancy, it is important for us to analyse the recent trends. Assisted reproductive technology has brought hope to many childless couples. But it comes with a price. The prevalence of multiple gestation globally at present is 32 per 1000 deliveries. Recent studies from India report an incidence of 30.5 per 1000 deliveries. The most important complication associated with multiple gestation is prematurity. From the neonatology point of view, the increase in multiple gestation has opened an additional opportunity for the neonatologists to see and manage more preterm babies. Infants born after a multifetal pregnancy are associated with an increased risk of prematurity, cerebral palsy, learning disabilities, slow language development, behavioural difficulties, chronic lung disease, developmental delay, and death. The relative risk of cerebral palsy in twins and triplets compared to a singleton is 4.9 and 12.7, respectively. Foetal reduction as a routine should be discussed with all couples with multiple gestation including twins, to improve the pregnancy and neonatal outcome. Any multifetal gestation is a high-risk pregnancy should be managed efficiently by a multidisciplinary team involving Senior Obstetricians, neonatologists, intensivists, anaesthesiologists, physicians and nursing team in a well-equipped centre.
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