203 research outputs found
Bound orbit domains in the phase space of the Kerr geometry
We derive the conditions for a non-equatorial eccentric bound orbit to exist
around a Kerr black hole in two-parameter spaces: the energy, angular momentum
of the test particle, spin of the black hole, and Carter's constant space (,
, , ), and eccentricity, inverse-latus rectum space (, , ,
). These conditions distribute various kinds of bound orbits in different
regions of the (, ) and (, ) planes, depending on which pair of
roots of the effective potential forms a bound orbit. We provide a prescription
to select these parameters for bound orbits, which are useful inputs to study
bound trajectory evolution in various astrophysical applications like
simulations of gravitational wave emission from extreme-mass ratio inspirals,
relativistic precession around black holes, and the study of gyroscope
precession as a test of general relativity.Comment: 7 pages, 2 figures, Conference: Proceedings of the MG15 Meeting on
General Relativit
A relativistic orbit model for temporal properties of AGN
We present a unified model for X-ray quasi-periodic oscillations (QPOs) seen
in Narrow-line Seyfert 1 (NLSy1) galaxies, -ray and optical band QPOs
that are seen in Blazars. The origin of these QPOs is attributed to the plasma
motion in corona or jets of these AGN. In the case of X-ray QPOs, we applied
the general relativistic precession model for the two simultaneous QPOs seen in
NLSy1 1H 0707-945 and deduce orbital parameters, such the radius of the
emission region, and spin parameter for a circular orbit; we obtained the
Carter's constant , , and the radius in the case of a spherical orbit
solution. In other cases where only one X-ray QPO is seen, we localized the
orbital parameters for NLSy1 galaxies REJ 1034+396, 2XMM J123103.2+110648, MS
2254.9-3712, Mrk 766, and MCG-06-30-15. By applying the lighthouse model, we
found that a kinematic origin of the jet based -ray and optical QPOs,
in a relativistic MHD framework, is possible. Based on the inbuilt Hamiltonian
formulation with a power-law distribution in the orbital energy of the plasma
consisting of only circular or spherical trajectories, we show that the
resulting Fourier power spectral density (PSD) has a break corresponding to the
energy at ISCO. Further, we derive connection formulae between the slopes in
the PSD and that of the energy distribution. Overall, given the preliminary but
promising results of these relativistic orbit models to match the observed QPO
frequencies and PSD at diverse scales in the inner corona and the jet, it
motivates us to build detailed models, including a transfer function for the
energy spectrum in the corona and relativistic MHD jet models for plasma flow
and its polarization properties.Comment: 28 pages, 11 figures [24 sub-figures], 6 Tables, final edited
version, Accepted in Galaxies; special issue on "X-ray flux and spectral
variability of Blazars
Eccentric equatorial trajectories around a Kerr black hole as a QPO model for M82X-1
We study the bound orbit conditions for equatorial and eccentric orbits
around a Kerr black hole both in the parameter space (, , )
representing the energy, angular momentum of the test particle, and spin of the
black hole, and also (, , ) space representing the eccentricity,
inverse-latus rectum of the orbit, and spin. We apply these conditions and
implement the relativistic precession (RP) model to M82X-1, which is an
Intermediate-mass black hole (IMBH) system, where two high-frequency
Quasi-Periodic Oscillations (HFQPOs) and a low-frequency QPO were
simultaneously observed. Assuming that the QPO frequencies can also be
generated by equatorial and eccentric trajectories, we calculate the
probability distributions to infer , , and periastron distance, , of
the orbit giving rise to simultaneous QPOs. We find that an eccentric orbit
solution is possible in the region between innermost stable circular orbit
(ISCO) and the marginally bound circular orbit (MBCO) for
, , and
.Comment: 7 pages, 2 figures, Conference: Proceedings of the MG15 Meeting on
General Relativit
Production of Doubled Haploids in Onion: A Review
Onion suffers from high inbreeding depression and, as a result, inbreds that are developed lack genotypic and phenotypic uniformity. Gynogenesis has emerged as a potential strategy to address this drawback. Efforts have been made since the 1980s for identifying highly-responsive genotypes and for overall improvement of the protocol for bettering gynogenic frequency in onion. Besides improving media composition, identification of responsive explants and increasing the chromosome efficiency has remained a major area of focus over the years. This article purports to review progress made thus far in the induction of gynogenic haploids in onion, and challenges/opportunities associated with it
A Longitudinal Examination of Peer Victimization on Depressive Symptoms Among Asian American School‑Aged Youth
The current study sought to examine the prospective relationship of peer victimization on changes in Asian American youth’s depressive symptoms during early adolescence, a crucial period for the development of depression and engagement in peer victimization among youth. Further, as guided by cultural–ecological frameworks, the current study also sought to examine the role of school-based peer support and gender as moderators on the relationship between peer victimization and depressive symptoms among this understudied population. Participants included Asian American youth (N = 232; M age = 12.96, SD = 1.40; 51% girls) who completed questionnaires in the school context. Data for this study included two measurement occasions over a 1-year interval. Results indicated that high levels of adolescents’ perceptions of peer victimization were associated with increased levels of depressive symptoms 1 year later. Additionally, results indicated that peer victimization interacted with reports of peer support within school, such that under conditions of moderate to high levels of school-based peer support, high levels of peer victimization related to increased depressive symptoms. Findings contribute to our understanding of the development of depressive symptoms among early adolescent Asian American youth and have implications for school-based depression prevention programming for Asian American youth
EVALUATION OF ACUTE AND SUB-ACUTE TOXICITY OF A STANDARDIZED POLYHERBAL FORMULATION (HC9): AN IN VIVO STUDY
Objective: In the present study, we have performed the acute and sub-acute toxicity of a standardized polyherbal formulation (HC9) in Swiss albino mice.
Methods: In acute toxicity study, the mice were orally administered with different doses (1750 and 2000 mg/kg) of HC9 and monitored for 14 d. In the sub-acute toxicity study, animals received HC9 extract by oral gavage at the doses of 250, 500 and 1000 mg/kg/day (????=5/group/sex) for 28 d. At the end of the study, the animals were sacrificed and evaluated for effect of HC9 on biochemical, hematological and histopathological parameters.
Results: HC9 did not produce any adverse effects in biochemical, hematological, urine and histopathological parameters in mice. HC9 did not induce any adverse effects in terms of mortality and clinical signs in the acute toxicity study. It was well-tolerated by mice up to 2000 mg/kg/body weight. In sub-acute toxicity study, no treatment-related adverse effects were found in the mice upto 1000 mg/kg/day dose. No significant changes were observed in biochemical and hematological parameters as well as histopathology of tissues (liver, kidney, spleen, heart, lung, thymus, adrenal gland, epididymis and testis/ovary) among mice of either sex.
Conclusion: Our results showed that HC9 did not induce any acute and sub-acute toxicity in male and female mice, thereby, suggesting its safety for future clinical application
Steady state and dynamic response of a state space observer based PMSM drive with different controllers
This paper deals with an investigation and evaluation of the performance of a state observer based Permanent Magnet Synchronous Motor (PMSM) drive controlled by PI (Proportional Integral), PID (Proportional Integral and Derivative), SMC (sliding mode control), ANN (Artificial neural network) and FLC (Fuzzy logic) speed controllers. A detailed study of the steady state and dynamic performance of estimated speed and angle is given to demonstrate the capability of the controllers
Effect of mid-day meal on nutritional status of adolescents: A cross-sectional study from Gujarat
Objective: To evaluate the effect of mid-day meal (MDM) on the nutritional status of adolescents and compare it with healthy comparison group. Settings and Design: A cross-sectional study on apparently healthy adolescents (10-14 years) receiving MDM and not receiving MDM (comparison group) was conducted in two cities (Ahmedabad and Patan) of Gujarat, Western India, from January 2012 to March 2014. Materials and Methods: A total of 401 adolescents (200 boys) were selected randomly, using computerized random number generation, from two private and two municipal/government schools. Anthropometric measurements were performed. Height, weight, and body mass index Z scores were computed using ethnic data. Diet was recorded by 24 h recall and nutrient intakes were computed (C-diet V-2.1) as a percentage of the recommended dietary allowance (RDA). Student’s t-test and Chi-square tests were used to compare differences in nutritional status. Results: Percentage of stunting (24% boys and 19% girls) and wasting (17% boys and 18% girls) was significantly higher in adolescents receiving MDM (p<0.001), while the percentage of risk of being overweight, i.e., BMI for age Z (BAZ) >1 or above 85th percentile (18% boys and 12% girls) was predominant in non-MDM receiving adolescents (p<0.001). Compared to non-MDM, MDM receiving adolescents consumed significantly reduced quantity of nutrients (p<0.05). On comparing RDA based on the 24 h dietary recall, it was seen that MDM receiving boys met 60% energy, 78% protein, 50% calcium, and 53% of micronutrient requirements while MDM receiving girls met 59% energy, 67% protein, 44% calcium, and 48% of micronutrient requirements. Non-MDM receiving adolescents had close to RDA or above intake for the most nutrients (p<0.05 for all). Conclusion: Although MDM scheme restricted the percentage of stunting to some extent, the percentage of wasting was critical in terms of public health significance. MDM receiving adolescents were vulnerable to energy, protein, and micronutrient deficiencies.Key words: Adolescents, Nutritional status, Micronutrients, Mid-da
- …