1,378 research outputs found

    Impact of photometric variability on age and mass determination of Young Stellar Objects: A case study on Orion Nebula Cluster

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    In case of pre-main sequence objects, the only way to determine age and mass is by fitting theoretical isochrones on color-magnitude (alternatively luminosity-temperature) diagrams. Since young stellar objects exhibit photometric variability over wide range in magnitude and colors, the age and mass determined by fitting isochrones is expected to be inaccurate, if not erroneous. These in turn will badly affect any study carried out on age spread and process of star formation. Since we have carried out very extensive photometric observations of the Orion Nebula Cluster (ONC), we decided to use our multi-band data to explore the influence of variability in determining mass and age of cluster members. In this study, we get the amplitudes of the photometric variability in V, R, and I optical bands of a sample of 346 ONC members and use it to investigate how the variability affects the inferred masses and ages and if it alone can take account for the age spread among the ONC members reported by earlier studies. We find that members that show periodic and smooth photometric rotational modulation have their masses and ages unaffected by variability. On other hand, we found that members with periodic but very scattered photometric rotational modulation and members with irregular variability have their masses and ages significantly affected. Moreover, using Hertzsprung-Russell (HR) diagrams we find that the observed I band photometric variability can take account of only a fraction (about 50%) of the inferred age spread, whereas the V band photometric variability is large enough to mask any age spread.Comment: Accepted by MNRAS; 17 pages, 4 Tables, 15 Figure

    Observation of R-Band Variability of L Dwarfs

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    We report, for the first time, photometric variability of L dwarfs in RR band. Out of three L1 dwarfs (2MASS 1300+19, 2MASS 1439+19, and 2MASS 1658+70) observed, we have detected R band variability in 2MASS 1300+19 and 2MASS 1439+19. The objects exhibit variability of amplitude ranging from 0.01 mag to 0.02 mag. Object 2MASS 1658+70, turns out to be non-variable in both RR and II band. However, more observations are needed to infer its variability. No periodic behaviour in the variability is found from the two L1 dwarfs that are variable. All the three L1 dwarfs have either negligible or no HαH_{\alpha} activity. In the absence of any direct evidence for the presence of sufficiently strong magnetic field, the detection of polarization at the optical favors the presence of dust in the atmosphere of L dwarfs. We suggest that the observed RR band photometric variability is most likely due to atmospheric dust activity.Comment: 13 pages (latex, aastex style) including 3 eps figures. Accepted for publication in The Astrophysical Journal Letter

    Nuevo registro de la biota ediacárica en la Arenisca de Jodhpur (Supergrupo de Marwar), Rajasthan occidental, India

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    In western Rajasthan, India, the Jodhpur Sandstone of the Marwar Supergroup has yielded a new Ediacaran fossil assemblage comprising macroscopic well-preserved specimens of Aspidella, Hiemalora, large Ediacaran discs, Tirasiana disciformis, Medusinites asteroides, Anfesta-like Ediacaran body fossils and microbial mat structures (Arumberia banksi, Kinneyia mat structures, wrinkle mat structures and other mat structures). The fossil record allows suggesting a broad correlation with the Fermuse Formation, Newfoundland, South Australia, White Sea of Russia and Norway, and regionally correlated with the Bhander Group of Vindhyan Supergroup and Krol Group of Lesser Himalaya.En el oeste de Rajasthan, India, la Arenisca de Jodhpur (Supergrupo de Marwar) ha librado un nuevo conjunto fósil ediacárico que comprende especímenes macroscópicos bien conservados de Aspidella, Hiemalora, grandes discos ediacáricos, Tirasiana disciformis, asteroides de Medusinites, fósiles de cuerpo blando ediacáricos similares a Anfesta y estructuras de tapices microbianas (Arumberia banksi, estructuras microbianas de tipo Kinneyia, estructuras microbianas arrugadas y otras estructuras microbianas). El registro fósil permite sugerir una amplia correlación con la Formación de Fermuse, Terranova, Australia meridional, el Mar Blanco de Rusia y Noruega, y la correlación regional con el Grupo de Bhander (Supergroup de Vindhyan) y el Grupo de Krol del Himalaya Interior

    Role of hysterolaparoscopy in the evaluation of female infertility in a tertiary care centre

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    Background: Infertility is one of the most important and underappreciated reproductive health problems in developing countries. Inability to conceive bears a social stigma which causes societal repercussion and personal suffering. The advent of hysterolaparoscopy have redefined the evaluation and treatment of infertile women. Study aimed to assess the role of hysterolaparoscopy in the evaluation of female infertility.Methods: This prospective observational study was done in the department of obstetrics and gynaecology, Gandhi Medical College, Sultania Zanana Hospital, Bhopal, during the period between 1st December 2016 to 30th November 2017. 104 infertile patients either with primary or secondary infertility were included after thorough evaluation.Results: Out of 104 infertile patients, 82(78.8%) women had primary infertility and rest 22(21.1%) women had secondary infertility. In primary infertility group, most common laparoscopic finding was PCOD in 24(29%) women and in secondary infertility group, tubal blockage was seen in 9(40%) women. The most common pathology seen in hysteroscopy was submucous fibroid in 6(7.3%) women with primary infertility, whereas in secondary infertility group, synechiae was found in 2(9%) patients and septum was seen in 1(4.5%) patient. Out of 104 patients, 33 (31.7%) patients underwent various interventions. The most common intervention was ovarian drilling for PCOS in 21(63.3%) patients followed by hysteroscopic cannulation in 5(15.5%) patients.Conclusions: Hysterolaparoscopy is a very useful tool that can detect various structural abnormalities in multiple sites like uterus, tubes, ovaries and peritoneal cavity in the same sitting. When done by experienced hands and proper selection of patients, hysterolaparoscopy can be considered as a definitive investigative procedure for evaluation of female infertility

    Oxidative Cleavage of Alpha Amino Acids ℓ–Glycine and ℓ–Valine By1,3-Dichloro-5,5-Dimethylhydantoin in Medium of Aqueous Acetic Acid Medium

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    Abstract: 1,3-dichloro-5,5-dimethylhydantoin (DCDMH) hydrolysed of this compounds leads to the formation of active positive halogen species like HOCl and H2O+Cl. The H2O+Cl in non-polar or less polar media, extensively used as a chlorinating and oxidizing agents in organic substrate. The rate of reaction is enhanced by the increasing [H+] and percentage of acetic acid. The main product of the oxidation is corresponding aldehydes. The thermodynamic parameters for the oxidation have been computed in the show step mechanism. The observed rate law was in good conformity with the mechanism

    Night sky at the Indian Astronomical Observatory during 2000-2008

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    We present an analysis of the optical night sky brightness and extinction coefficient measurements in UBVRI at the Indian Astronomical Observatory (IAO), Hanle, during the period 2003-2008. They are obtained from an analysis of CCD images acquired at the 2 m Himalayan Chandra Telescope at IAO. Night sky brightness was estimated using 210 HFOSC images obtained on 47 nights and covering the declining phase of solar activity cycle-23. The zenith corrected values of the moonless night sky brightness in mag/square arcsecs are 22.14(U), 22.42(B), 21.28(V), 20.54(R) and 18.86(I) band. This shows that IAO is a dark site for optical observations. No clear dependency of sky brightness with solar activity is found. Extinction values at IAO are derived from an analysis of 1325 images over 58 nights. They are found to be 0.36 in U-band, 0.21 in B-band, 0.12 in V-band, 0.09 in R-band and 0.05 in I-band. On average, extinction during the summer months is slightly larger than that during the winter months. No clear evidence for a correlation between extinction in all bands and the average night time wind speed is found. Also presented here is the low resolution moonless optical night sky spectrum for IAO covering the wavelength range 3000-9300 \AA. Hanle region thus has the required characteristics of a good astronomical site in terms of night sky brightness and extinction, and could be a natural candidate site for any future large aperture Indian optical-infrared telescope(s).Comment: 18 pages, 7 figures, uses basi.cls, accepted for publication in Bulletin of the Astronomical Society of Indi

    Anatomical variations of sphenoid sinus on multi-detector computed tomography and its usefulness in trans-sphenoidal endoscopic skull base surgery

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    Background: Knowledge of sphenoid bone and sinus anatomy and its variations is of central importance in transsphenoidal endoscopic skull base surgery. It allows endoscopic surgeon to safely approach the sella turcica, anterior skull base and orbit. The aim of the study was to evaluate the different anatomical variations of the sphenoid sinus that are relevant to trans-sphenoid endoscopic skull base surgery on multi-detector computed tomography.Methods: A prospective observational study of the CT analysis of the anatomical variations and various dimensions of sphenoid sinus relevant to trans-sphenoidal endoscopic neurosurgery was performed in 260 patients (173 male; 87 female).Results: The average presellar width of sphenoid sinus on axial CT scan images was 11.75mm (7.2 to 18.6mm). Average value of maximum width of sphenoid sinus was 30.52 mm (13.1 to 42.2 mm). The most common pattern of inter-sphenoid septum was single septum which was present in 207 patients (79.61%); double inter sphenoid septum in 47 patients (18.1%) and diverging septa in 13 patients (5%). 138 out of 260 subjects (53%) showed at least one septum attached to either carotid protuberance. Most common pattern of pneumatization in sphenoid sinus was sellar type (63.46%). Average suprasellar depth was 10.78 (5.4 to 18.7mm). Average presellar depth of sphenoid sinus was 13.47mm (8.1 to 22.5mm). Average infrasellar depth of sphenoid sinus was 25.46mm (11.9 to 37.9mm). Average presellar height of sphenoid sinus was 21.27mm (13 to 27.6mm).Conclusions: A preoperative review of the sphenoid sinus anatomy by CT allows safer endoscopic management of skull base pathology preventing injury to vital structures surrounding the sphenoid sinus

    Effect of Oxidant 1, 3-Dichloro-5-5-Dimethylhydantoin and 5, 5-Dimethylhydantoin with Different Substrates: The Kinetic Measurements

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    The kinetic measurement with different concentration of oxidant 1,3-dichloro-5,5-dimethylhydantoin and 5,5-dimethylhydantoin with ℓ–alanine,  â„“-glycine and ℓ–valine. The catalytic effect of acid in the reaction rate reveal an interaction between oxidants species H2O+Cl and substrates. The observed order of reactivity of â„“-amino acids (â„“-glycine > ℓ–alanine > â„“-valine) was explained on the basis of hydrolysis of reacting species
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