26 research outputs found
Dust properties from GALEX observations of a UV halo around Spica
GALEX has detected ultraviolet halos extending as far as 5 around
four bright stars (Murthy et al. (2011)). These halos are produced by
scattering of starlight by dust grains in thin foreground clouds that are not
physically associated with the star. Assuming a simple model consisting of a
single layer of dust in front of the star, Murthy et al.(2011) have been able
to model these halo intensities and constrain the value of the phase function
asymmetry factor of the scattering grains in the FUV and NUV. However due
to the uncertainty in the dust geometry they could not constrain the albedo. In
this work we have tried to constrain the optical constants and dust geometry by
modeling the UV halo of Spica. Since the halo emission is not symmetric, we
have modeled the Northern and Southern parts of the halo separately. To the
North of Spica, the best-fit albedo is 0.260.1 and is 0.580.11 in
the FUV at the 90% confidence level. The corresponding limits on the distance
and optical depth () of the dust sheet is 3.651.05 pc and
0.0470.006 respectively. However, owing to a complicated dust distribution
to the South of Spica, we were unable to uniquely constrain the dust parameters
in that region. Nevertheless, by assuming the optical constants of the Northern
region and assuming a denser medium, we were able to constrain the distance of
the dust to 9.51.5 pc and the corresponding to 0.040.01.Comment: 4 pages, accepted for publication in Earth, Planets and Spac
A Field Programmable Gate Array (FPGA) Based Non-Linear Filters for Gas Turbine Prognostics
The removal of noise from signals obtained through the health monitoring systems in gas turbines is an important consideration for accurate prognostics. Several filters have been designed and tested for this purpose, and their performance analysis has been conducted. Linear filters are inefficient in the removal of outliers and noise because they cause smoothening of the sharp features in the signal which can indicate the onset of a fault event. On the other hand, non-linear filters based on image processing methods can provide more precise results for gas turbine health signals. Among others, the weighted recursive median (WRM) filter has been shown to provide greater accuracy due to its weight adaptability depending on the signal type. However, sampling data at high rates is possible which needs hardware implementation of the filter. In this paper, the design, simulation and implementation of WRM filters on the FPGA (Field Programmable Gate Arrays) platforms Vivado Design Suite by Xilinx and Quartus Pro Lite Edition 19.3 has been performed. The architectural detail and performance result with the FPGA filters when subjected to abrupt and gradual fault signal is presented
A 3D Automated Classification Scheme for the TAUVEX data pipeline
In order to develop a pipeline for automated classification of stars to be
observed by the TAUVEX ultraviolet space Telescope, we employ an artificial
neural network (ANN) technique for classifying stars by using synthetic spectra
in the UV region from 1250\AA to 3220\AA as the training set and International
Ultraviolet Explorer (IUE) low resolution spectra as the test set. Both the
data sets have been pre-processed to mimic the observations of the TAUVEX
ultraviolet imager. We have successfully classified 229 stars from the IUE low
resolution catalog to within 3-4 spectral sub-class using two different
simulated training spectra, the TAUVEX spectra of 286 spectral types and UVBLUE
spectra of 277 spectral types. Further, we have also been able to obtain the
colour excess (i.e. E(B-V) in magnitude units) or the interstellar reddening
for those IUE spectra which have known reddening to an accuracy of better than
0.1 magnitudes. It has been shown that even with the limitation of data from
just photometric bands, ANNs have not only classified the stars, but also
provided satisfactory estimates for interstellar extinction. The ANN based
classification scheme has been successfully tested on the simulated TAUVEX data
pipeline. It is expected that the same technique can be employed for data
validation in the ultraviolet from the virtual observatories. Finally, the
interstellar extinction estimated by applying the ANNs on the TAUVEX data base
would provide an extensive extinction map for our galaxy and which could in
turn be modeled for the dust distribution in the galaxy.Comment: 8 pages, 12 figures, Accepted for publication in MNRAS; High
resolution figures available from the authors on reques
FiziÄkokemijska karakterizacija inkluzijskih kompleksa celekoksiba s beta-ciklodekstrinom i oslobaÄanje celekoksiba in vitro
In this study, attempts were made to investigate the effects of betha-cyclodextrin (betha-CD) on the aqueous solubility and dissolution rate of celecoxib. Inclusion complexes were prepared by the kneading method and characterized by SEM, NMR, IR, DSC, and X-ray powder diffraction. Dissolution rate of the complexes was significantly greater than that of the corresponding physical mixtures and pure drug, indicating that the formation of inclusion complex increased the solubility of the poorly soluble drug celecoxib.U radu je ispitivan utjecaj beta-ciklodekstrina (beta-CD) na vodotopljivost i oslobaÄanje celekoksiba iz inkluzijskih kompleksa. Kompleksi su prireÄeni metodom gnjeÄenja i karakterizirani pomoÄu SEM, NMR, IR, DSC i difrakcijom rentgenskim zraÄenjem. OslobaÄanje iz kompleksa bilo je znaÄajno bolje nego iz fiziÄke smjese ĆĄto ukazuje da je stvaranje inkluzijskog kompleksa poveÄalo topljivost teĆĄko topljivog celekoksiba
UVIT study of UV bright stars in the globular cluster NGC 4147
We present far ultraviolet (FUV) observations of globular cluster NGC 4147 using three FUV filters, BaF2 (F154W), sapphire (F169M), and silica (F172M) of Ultra-Violet Imaging Telescope (UVIT) on-board 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 (Teff) 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
Canagliflozin and renal outcomes in type 2 diabetes and nephropathy
BACKGROUND Type 2 diabetes mellitus is the leading cause of kidney failure worldwide, but few effective long-term treatments are available. In cardiovascular trials of inhibitors of sodiumâglucose cotransporter 2 (SGLT2), exploratory results have suggested that such drugs may improve renal outcomes in patients with type 2 diabetes. METHODS In this double-blind, randomized trial, we assigned patients with type 2 diabetes and albuminuric chronic kidney disease to receive canagliflozin, an oral SGLT2 inhibitor, at a dose of 100 mg daily or placebo. All the patients had an estimated glomerular filtration rate (GFR) of 30 to <90 ml per minute per 1.73 m2 of body-surface area and albuminuria (ratio of albumin [mg] to creatinine [g], >300 to 5000) and were treated with reninâangiotensin system blockade. The primary outcome was a composite of end-stage kidney disease (dialysis, transplantation, or a sustained estimated GFR of <15 ml per minute per 1.73 m2), a doubling of the serum creatinine level, or death from renal or cardiovascular causes. Prespecified secondary outcomes were tested hierarchically. RESULTS The trial was stopped early after a planned interim analysis on the recommendation of the data and safety monitoring committee. At that time, 4401 patients had undergone randomization, with a median follow-up of 2.62 years. The relative risk of the primary outcome was 30% lower in the canagliflozin group than in the placebo group, with event rates of 43.2 and 61.2 per 1000 patient-years, respectively (hazard ratio, 0.70; 95% confidence interval [CI], 0.59 to 0.82; P=0.00001). The relative risk of the renal-specific composite of end-stage kidney disease, a doubling of the creatinine level, or death from renal causes was lower by 34% (hazard ratio, 0.66; 95% CI, 0.53 to 0.81; P<0.001), and the relative risk of end-stage kidney disease was lower by 32% (hazard ratio, 0.68; 95% CI, 0.54 to 0.86; P=0.002). The canagliflozin group also had a lower risk of cardiovascular death, myocardial infarction, or stroke (hazard ratio, 0.80; 95% CI, 0.67 to 0.95; P=0.01) and hospitalization for heart failure (hazard ratio, 0.61; 95% CI, 0.47 to 0.80; P<0.001). There were no significant differences in rates of amputation or fracture. CONCLUSIONS In patients with type 2 diabetes and kidney disease, the risk of kidney failure and cardiovascular events was lower in the canagliflozin group than in the placebo group at a median follow-up of 2.62 years
Naval Maritime Physician : Roles and Challenges
Background: Naval maritime physician is a trained doctor who is responsible for providing promotive, preventive and curative health care to the shipâČs crew. Injuries and sickness of seafarerâČs has existed since the time man learned sea travel In earlier day the duties of maritime physician were performed by the captain or barber surgeons who used archaic remedies such as treating sores from the ropes on sailorsâČ hands with suffererâČs urine, turpentine for rheumatic pains, limb injuries were frequently treated with amputation and most popular cure for all ailments was always gin, rum or whiskey. Then came the diplomed physicians and trained medical officers on war ships who were wardroom warrant officers and it was only in 1808 that the medical officers were given commissioned ranks. Over the centuries the role of naval maritime physicians has evolved to provide high standards of care even in adverse conditions and with minimal support.
Roles and challenges: Good maritime medicalpractice involves meeting numerous challenges of clinical, occupational, emergency, trauma and psychiatric medicine, in addition on board physicians must also have, in depth knowledge of pschycosomatic conditions due to stress andfatigue of crew and special conditions such as diving accidents and accidents involving aquatic animals. The situation on board requires extraordinary skills as interventions are difficult, both physically and technically, because the conditions at sea are often acrobatic and at certain times evacuation is also not possible due to weather and operational constraints. Thus the role naval doctor on board ships is truly of an all round physicians, a team mate and a good leader.
Conclusion: In conclusion, responsibilities of Naval Maritime Physician is not limited to clinical activities but is multifaceted and objective training about the specifics of warshipsâČ environment and related health problems is the key to achieve professional excellence in every sphere