66 research outputs found
Investigation of Rocket Effect in Bright-Rimmed Clouds using Gaia EDR3
Bright-rimmed clouds (BRCs) are excellent laboratories to explore the
radiation-driven implosion mode of star formation because they show evidence of
triggered star formation. In our previous study, BRC 18 has been found to
accelerate away from the direction of the ionizing Hii region because of the
well known "Rocket Effect". Based on the assumption that both BRC 18 and the
candidate young stellar objects (YSOs) are kinematically coupled and using the
latest Gaia EDR3 measurements, we found that the relative proper motions of the
candidate YSOs exhibit a tendency of moving away from the ionizing source.
Using BRC 18 as a prototype, we made our further analysis for 21 more BRCs, a
majority of which showed a similar trend. For most of the BRCs, the median
angle of the relative proper motion of the candidate YSOs is similar to the
angle of on-sky direction from the ionizing source to the central IRAS source
of the BRC. Based on Pearson's and Spearman's correlation coefficients, we
found a strong correlation between these two angles, which is further supported
by the Kolmogorov-Smirnov (K-S) test on them. The strong correlation between
these two angles supports the "Rocket Effect" in the BRCs on the plane-of-sky
Magnetic fields and young stellar objects in cometary cloud LDN 1616
LDN 1615/1616 and CB 28 (hereafter, L1616) together form a cometary globule
located at an angular distance of about 8 degrees west of the Orion OB1
association, aligned roughly along the east-west direction, and showing a
distinct head-tail structure. The presence of massive stars in the Orion belt
has been considered to be responsible for the radiation driven implosion mode
of star formation in L1616. Based on the latest Gaia EDR3 measurements of the
previously known young stellar objects (YSOs) associated with L1616, we find
the distance to this cloud of 3845 pc. We present optical polarimetry
towards L1616 that maps the plane-of-sky component of the ambient magnetic
field (B) geometry. Based on the proper motion of the YSOs associated
with L1616, we investigate their plane-of-sky motion relative to the exciting
star Ori. Using the Gaia EDR3 measurements of the distances and
proper motions of the YSOs, we find two additional sources comoving with the
known YSOs. One comoving source is HD33056, a B9 star and the other might be a
young pre-main sequence star not reported in previous studies. The mean
direction of B is found to follow the cloud structure. This could be
the effect of dragging of the magnetic field lines by the impact of the
ionizing radiation from Ori. Based on the pressure exerted on L1616,
and the ages of the associated YSOs, we show that it could possibly be the main
source of ionization in L1616, and thus the star formation in it
Distance, magnetic field and kinematics of a filamentary cloud LDN 1157
LDN 1157, is one of the several clouds situated in the cloud complex, LDN
1147/1158, represents a coma-shaped morphology with a well-collimated bipolar
outflow emanating from a Class 0 protostar, LDN 1157-mm. The main goals of this
work are (a) to map the inter-cloud magnetic field (ICMF) geometry of the
region surrounding LDN 1157 to investigate its relationship with the cloud
morphology, with the outflow direction and with the core magnetic field (CMF)
geometry inferred from the mm- and sub-mm polarization results from the
literature, and (b) to investigate the kinematic structure of the cloud. We
carried out R-band polarization observations of the stars projected on the
cloud to map the pc-scale magnetic field geometry and made spectroscopic
observations of the entire cloud in 12CO, C18O and N2H+ (J=1-0) lines to
investigate its kinematic structure. We obtained a distance of 3403 pc to
the LDN 1147/1158, complex based on the Gaia DR2 parallaxes and proper motion
values of the three YSOs associated with the complex. A single filament of
pc in length and pc in width is found to run all along the
coma-shaped cloud. Based on the relationships between the ICMF, CMF, filament
orientations, outflow direction, and the presence of an hour-glass morphology
of the magnetic field, it is likely that the magnetic field had played an
important role in the star formation process in LDN 1157. Combining the proper
motions of the YSOs and the radial velocity of LDN 1147/1158 and another
complex LDN 1172/1174 which is situated \dgr~east of it, we found that
both the complexes are moving collectively toward the Galactic plane. The
filamentary morphology of the east-west segment of LDN 1157 may have formed as
a result of mass lost by ablation due to the interaction of the moving cloud
with the ambient interstellar medium.Comment: 20 pages, Accepted in Astronomy & Astrophysics, Abstract has been
shortened due to word limit in arxi
Investigation of Rocket Effect in BRC 18 using Gaia EDR3
Bright-rimmed clouds (BRCs) are ideal candidates to study radiation-driven implosion mode of star formation as they are potential sites of triggered star formation, located at the edges of HII regions, showing evidence of ongoing star formation processes. BRC 18 is located towards the eastern edge of relatively closer (similar to 400 pc) H II region excited by lambda Ori. We made R-band polarimetric observations of 17 candidate young stellar objects (YSOs) located towards BRC 18 to investigate any preferred orientation of the discs with respect to the ambient magnetic field and the direction of energetic photons from lambda Ori. We found that the discs are oriented randomly with respect to the projected magnetic field. Using distances and proper motions from the Gaia EDR3 of the candidate YSOs, we investigated the possible acceleration of BRC 18, away from lambda Ori due to the well-known 'Rocket Effect', by assuming that both the candidate YSOs and BRC 18 are kinematically coupled. The relative proper motions of the candidate YSOs are found to show a trend of moving away from lambda Ori. We computed the offset between the angle of the direction of the ionization front and the relative proper motion of the candidate YSOs and found it to lie close to being parallel to each other. Additionally, we found 12 sources that are co-moving with the known candidate YSOs towards BRC 18. These co-moving sources are most likely to be young and are missed in previous surveys conducted to identify potential YSOs of the region
Aspirin and low-molecular weight heparin combination therapy effectively prevents recurrent miscarriage in hyperhomocysteinemic women.
The management of recurrent pregnancy loss (RPL) still remains a great challenge, and women with polycystic ovarian syndrome (PCOS) are at a greater risk for spontaneous abortion. Treatment with low-molecular-weight heparin (LMWH) has become an accepted treatment option for women with RPL; however, the subgroup of women, who are likely to respond to LMWH, has not been precisely identified. The present study evaluated the efficacy of LMWH with reference to PCOS and associated metabolic phenotypes including hyperhomocysteinemia (HHcy), insulin resistance (IR) and obesity. This prospective observational study was conducted at Institute of Reproductive Medicine, Kolkata, India. A total of 967 women with history of 2 or more consecutive first trimester abortions were screened and 336 were selected for the study. The selected patients were initially divided on the basis of presence or absence of PCOS, while subsequent stratification was based on HHcy, IR and/or obesity. The subjects had treatment with aspirin during one conception cycle and aspirin-LMWH combined anticoagulant therapy for the immediate next conception cycle, if the first treated cycle was unsuccessful. Pregnancy salvage was the sole outcome measure. The overall rate of pregnancy salvage following aspirin therapy was 43.15%, which was mostly represented by normohomocysteinemic women, while the salvage rate was lower in the HHcy populations irrespective of the presence or absence of PCOS, IR, or obesity. By contrast, aspirin-LMWH combined therapy could rescue 66.84% pregnancies in the aspirin-failed cases. Logistic regression analyses showed that HHcy remained a significant factor in predicting salvage rates in the PCOS, IR, and obese subpopulations controlled for other confounding factors. With regard to pregnancy salvage, combined anticoagulant therapy with aspirin and LMWH conferred added benefit to those with HHcy phenotype
Ovotoxic Effects of Galactose Involve Attenuation of Follicle-Stimulating Hormone Bioactivity and Up-Regulation of Granulosa Cell p53 Expression
Clinical evidence suggests an association between galactosaemia and premature ovarian insufficiency (POI); however, the mechanism still remains unresolved. Experimental galactose toxicity in rats produces an array of ovarian dysfunction including ovarian development with deficient follicular reserve and follicular resistance to gonadotrophins that characterize the basic tenets of human POI. The present investigation explores if galactose toxicity in rats attenuates the bioactivity of gonadotrophins or interferes with their receptor competency, and accelerates the rate of follicular atresia. Pregnant rats were fed isocaloric food-pellets supplemented with or without 35% D-galactose from day-3 of gestation and continuing through weaning of the litters. The 35-day old female litters were autopsied. Serum galactose-binding capacity, galactosyltransferase (GalTase) activity, and bioactivity of FSH and LH together with their receptor competency were assessed. Ovarian follicular atresia was evaluated in situ by TUNEL. The in vitro effects of galactose were studied in isolated whole follicles in respect of generation of reactive oxygen species (ROS) and expression of caspase 3, and in isolated granulosa cells in respect of mitochondrial membrane potential, expression of p53, and apoptosis. The rats prenatally exposed to galactose exhibited significantly decreased serum GalTase activity and greater degree of galactose-incorporation capacity of sera proteins. LH biopotency and LH-FSH receptor competency were comparable between the control and study population, but the latter group showed significantly attenuated FSH bioactivity and increased rate of follicular atresia. In culture, galactose increased follicular generation of ROS and expression of caspase 3. In isolated granulosa cells, galactose disrupted mitochondrial membrane potential, stimulated p53 expression, and induced apoptosis in vitro; however co-treatment with either FSH or estradiol significantly prevented galactose-induced granulosa cell p53 expression. We conclude that the ovotoxic effects of galactose involves attenuation of FSH bioactivity that renders the ovary resistant to gonadotrophins leading to increased granulosa cell expression of p53 and follicular atresia
ASSESSMENT OF OCCUPATIONAL STRESSES AMONG POLICE OFFICERS WHO IMPART TEACHING IN POLICE TRAINING COLLEGE, WEST BENGAL
ABSTRACT According to the Anshel (2000) police work has been regarded as one of the stressful occupations in the world. Police force provides continuous service to the people. The police force has to serve around the clock for proper investigation, safety and justice. All police personnel have to prepare for responding efficiently and properly even for the unforeseen and unpredictable incidents. But only a few studies were carried out in India in ergonomic point of view. The present study was conducted to evaluate the psycho-physiological characteristics and occupational stress of police officers who were teaching in police training college as a teacher and have a huge experience of stress in police station jobs. Apart from questionnaire study, psychological study was conducted to evaluate occupational stresses of police officers. Data was analyzed into computer by using statistical software for SPSS version 16.0 for the analyzing mean, standard deviation, upper and lower limit, agglomeration schedule. Cluster analysis, factor analysis, correlation and multiple regressions. After analyzing the data it was found that high ratings for stressors were contact with criminals, lack of a modern system, boring daily duty, lack of resource etc. Study also revealed that many stressors were correlated to each other. Regression model showed that lack of modern system, negatives criticisms to police are responsible for heavy work load and stresses. On the contrary temptation for taking bribe is there to reduce the score of heavy work load and stresses
Ventilator-associated pneumonia: Its incidence, the risk factor and drug resistance pattern in a tertiary care hospital
Background: Ventilator-associated pneumonia (VAP) is an infection of the lung that develops 48 h or longer after mechanical ventilation. Objectives: The present study was aimed to find out the bacteriological profile of VAP along with the resistance pattern of bacteriological isolates. Materials and Methods: A prospective observational study was conducted from January 2013 to May 2014 among 791 patients admitted in critical care units of our tertiary care hospital. After selection by applying inclusion and exclusion criteria endotracheal aspirates were collected from ventilated patients. Samples were subjected to further processing by Gram-staining, culture, biochemical testing and antibiogram. Results : Out of 791 patients admitted in intensive care unit in this tertiary care hospital with VAP 540 (68.2%) patients were culture positive. Pseudomonas aeruginosa was most commonly isolated pathogen of both early onset and late onset VAP. In early VAP Acinetobacter baumannii showed 62.5% metallo-beta-lactamase (MBL) positivity. P. aeruginosa showed 27.5% MBL positivity, whereas in late onset VAP, 71.4% A. baumannii isolates and 75.8% P. aeruginosa isolates showed MBL positivity, respectively. Conclusion : Simple prevention of aspiration, sterilization of equipments, hand washing of personnel can reduce VAP in hospital care setting
Detection of spreader nodes in human-SARS-CoV protein-protein interaction network
The entire world is witnessing the coronavirus pandemic (COVID-19), caused by a novel coronavirus (n-CoV) generally distinguished as Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2). SARS-CoV-2 promotes fatal chronic respiratory disease followed by multiple organ failure, ultimately putting an end to human life. International Committee on Taxonomy of Viruses (ICTV) has reached a consensus that SARS-CoV-2 is highly genetically similar (up to 89%) to the Severe Acute Respiratory Syndrome Coronavirus (SARS-CoV), which had an outbreak in 2003. With this hypothesis, current work focuses on identifying the spreader nodes in the SARS-CoV-human protein–protein interaction network (PPIN) to find possible lineage with the disease propagation pattern of the current pandemic. Various PPIN characteristics like edge ratio, neighborhood density, and node weight have been explored for defining a new feature spreadability index by which spreader proteins and protein–protein interaction (in the form of network edges) are identified. Top spreader nodes with a high spreadability index have been validated by Susceptible-Infected-Susceptible (SIS) disease model, first using a synthetic PPIN followed by a SARS-CoV-human PPIN. The ranked edges highlight the path of entire disease propagation from SARS-CoV to human PPIN (up to level-2 neighborhood). The developed network attribute, spreadability index, and the generated SIS model, compared with the other network centrality-based methodologies, perform better than the existing state-of-art
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