2,715 research outputs found

    The Variation of Integrated Star IMFs among Galaxies

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    The integrated galaxial initial mass function (IGIMF) is the relevant distribution function containing the information on the distribution of stellar remnants, the number of supernovae and the chemical enrichment history of a galaxy. Since most stars form in embedded star clusters with different masses the IGIMF becomes an integral of the assumed (universal or invariant) stellar IMF over the embedded star-cluster mass function (ECMF). For a range of reasonable assumptions about the IMF and the ECMF we find the IGIMF to be steeper (containing fewer massive stars per star) than the stellar IMF, but below a few Msol it is invariant and identical to the stellar IMF for all galaxies. However, the steepening sensitively depends on the form of the ECMF in the low-mass regime. Furthermore, observations indicate a relation between the star formation rate of a galaxy and the most massive young stellar cluster in it. The assumption that this cluster mass marks the upper end of a young-cluster mass function leads to a connection of the star formation rate and the slope of the IGIMF above a few Msol. The IGIMF varies with the star formation history of a galaxy. Notably, large variations of the IGIMF are evident for dE, dIrr and LSB galaxies with a small to modest stellar mass. We find that for any galaxy the number of supernovae per star (NSNS) is suppressed relative to that expected for a Salpeter IMF. Dwarf galaxies have a smaller NSNS compared to massive galaxies. For dwarf galaxies the NSNS varies substantially depending on the galaxy assembly history and the assumptions made about the low-mass end of the ECMF. The findings presented here may be of some consequence for the cosmological evolution of the number of supernovae per low-mass star and the chemical enrichment of galaxies of different mass.Comment: 27 pages, accepted for publication by Ap

    Star Clusters in the Magellanic Clouds-1: Parameterisation and Classification of 1072 Clusters in the LMC

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    We have introduced a semi-automated quantitative method to estimate the age and reddening of 1072 star clusters in the Large Magellanic Cloud (LMC) using the Optical Gravitational Lensing Experiment (OGLE) III survey data. This study brings out 308 newly parameterised clusters. In a first of its kind, the LMC clusters are classified into groups based on richness/mass as very poor, poor, moderate and rich clusters, similar to the classification scheme of open clusters in the Galaxy. A major cluster formation episode is found to happen at 125 +- 25 Myr in the inner LMC. The bar region of the LMC appears prominently in the age range 60 - 250 Myr and is found to have a relatively higher concentration of poor and moderate clusters. The eastern and the western ends of the bar are found to form clusters initially, which later propagates to the central part. We demonstrate that there is a significant difference in the distribution of clusters as a function of mass, using a movie based on the propagation (in space and time) of cluster formation in various groups. The importance of including the low mass clusters in the cluster formation history is demonstrated. The catalog with parameters, classification, and cleaned and isochrone fitted CMDs of 1072 clusters, which are available as online material, can be further used to understand the hierarchical formation of clusters in selected regions of the LMC.Comment: 19 pages, 19figures, published in MNRAS on August 16, 2016 Supplementary material is available in the MNRAS websit

    STABILITY INDICATING RP HPLC METHOD FOR THE ESTIMATION OF ARMODAFINIL IN TABLET DOSAGE FORM

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    Objective: To develop simple reverse phase HPLC method for the estimation of Armodafinil in tablet dosage form. Methods: Chromatography was performed by isocratic elution on a Stainless steel Hibar C18 column with dimensions 4.6 x 250 mm, packed with octadecylsilane bonded to porous silica (C18) with particle size 5 micron. Acetonitrile and water in the ratio of 50:50 v/v is used as mobile phase. The flow rate is 1.0 ml/ min and effluent is monitored at 220 nm. Armodafinil was eluted at a retention time of 3.8 minutes. Results: The standard curve of Armodafinil was linear over a working range of 1–700 µg/ml and gave an average correlation coefficient of 0.999. The limit of quantitation (LOQ) of the drug is 0.1 µg/ ml. Recovery studies were carried out by standard addition method and the recoveries are found satisfactory within the range of 99.3 to 101.5 %. The method is precise with % RSD below Conclusion: The method is validated in terms of robustness and forced degradation studies were carried out and this method can be applied for routine degradation studies ans quantification in regular laboratories

    Analysis of Box Culvert to Reduce Stress Values

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    At the time of construction of roads, highways a structure is placed (commonly used) to transfer the traffic, rain water, drainage from one side to another of the road is called a culvert placed beneath the road. Due to the structural use, multiple loads are placed on the box causing various types of stress which occurs on it. The paper tries to reduce the stress occurred in the box by flaring the box partially

    Star Clusters in the Magellanic Clouds - II. Age-Dating, Classification and Spatio-Temporal Distribution of the SMC Clusters

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    Aim: We aim to estimate the age and reddening parameters of already identified star clusters within the Small Magellanic Cloud (SMC) in a consistent way using available photometric data, classify them based on their mass and strength, and study their spatio- temporal distribution. Methods: We have used a semi-automated quantitative method, developed in the first paper of this series (Paper I), to estimate the cluster parameters using the V and I band photometric data from the Optical Gravitational Lensing Experiment (OGLE) III survey. Results: We estimated parameters of 179 star clusters (17 newly parameterised) and classified them into 4 groups. We present an online catalog of parameters, and cleaned and isochrone-fitted Color Magnitude Diagrams of 179 clusters. We compiled age information of 468 clusters by combining previous studies with our catalog, to study their spatio-temporal distribution. Most of the clusters located in the southern part of the SMC are in the age range 600 Myr-1.25 Gyr, whereas, the clusters younger than 100 Myr are mostly found in the northern SMC, with the central SMC showing continuous cluster formation. The peak of the cluster age distribution is identified at 130 Myr, very similar to the Large Magellanic Cloud (LMC) in Paper I. Conclusion: We suggest that the burst of cluster formation at 130 Myr is due to the most recent LMC-SMC interaction. 90% of the studied sample is found to have mass <1700 M_sun, suggesting that the SMC is dominated by low mass clusters. There is a tentative evidence for compact clusters in the LMC when compared to those in the Galaxy and the SMC. A progressive shifting of cluster location from the South to North of the SMC is identified in last 600 Myr. The details of spatio-temporal distribution of clusters presented in two videos in this study can be used as a tool to constrain details of the recent LMC-SMC interactions.Comment: The paper is accepted for publication in A&A journa

    Multibiometric Authentication System Processed by the Use of Fusion Algorithm

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    The present day authentication system is mostly uni-model i.e having only single authentication method which can be either finger print, iris , palm veins ,etc. Thus these models have to contend with a variety of problems such as absurd or unusual data, non-versatility; un authorized attempts, and huge amount of error rates. Some of these limitations can be reduced or stopped by the use of multimodal biometric systems that integrate the evidence presented by several sources of information. This paper converses a multi biometric based authentication system based on Fusion algorithm using a key. Our work mainly focuses on the fusion algorithm, i.e fusion of finger and palm print out of which the greatest features from the above two traits are taken into account. With minimum possible features the fusion of the both the traits is carried out. Then some key is generated for multi biometric authentication. By processing the test image of a person, the identity of the person is displayed with his/her own image. By the fusion algorithm, it is found that it has less computation time compared to the existing algorithms. By matching results, we validate and authenticate the particular individual

    A Raman study of the Charge-Density-Wave State in A0.3_{0.3}MoO3_3 (A = K,Rb)

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    We report a comparative Raman spectroscopic study of the quasi-one-dimensional charge-density-wave systems \ab (A = K, Rb). The temperature and polarization dependent experiments reveal charge-coupled vibrational Raman features. The strongly temperature-dependent collective amplitudon mode in both materials differ by about 3 cm, thus revealing the role of alkali atom. We discus the observed vibrational features in terms of charge-density-wave ground state accompanied by change in the crystal symmetry. A frequency-kink in some modes seen in \bb between T = 80 K and 100 K supports the first-order lock-in transition, unlike \rb. The unusually sharp Raman lines(limited by the instrumental response) at very low temperatures and their temperature evolution suggests that the decay of the low energy phonons is strongly influenced by the presence of the temperature dependent charge density wave gap.Comment: 13 pages, 7 figure

    CCD photometric and mass function study of 9 young Large Magellanic Cloud star clusters

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    We present CCD photometric and mass function study of 9 young Large Magellanic Cloud star clusters namely NGC 1767, NGC 1994, NGC 2002, NGC 2003, NGC 2006, SL 538, NGC 2011, NGC 2098 and NGC 2136. The BVRI data reaching down to V ~ 21 mag, are collected from 3.5-meter NTT/EFOSC2 in sub-arcsec seeing conditions. For NGC 1767, NGC 1994, NGC 2002, NGC 2003, NGC 2011 and NGC 2136, broad band photometric CCD data are presented for the first time. Seven of the 9 clusters have ages between 16 to 25 Myr while remaining two clusters have ages 32±432\pm4 Myr (NGC 2098) and 90±1090\pm10 Myr (NGC 2136). For 7 younger clusters, the age estimates based on a recent model and the integrated spectra are found to be systematically lower (\sim 10 Myr) from the present estimate. In the mass range of 212\sim 2 - 12 MM_{\odot}, the MF slopes for 8 out of nine clusters were found to be similar with the value of γ\gamma ranging from 1.90±0.16-1.90\pm0.16 to 2.28±0.21-2.28\pm0.21. For NGC 1767 it is flatter with γ=1.23±0.27\gamma = -1.23\pm0.27. Mass segregation effects are observed for NGC 2002, NGC 2006, NGC 2136 and NGC 2098. This is consistent with the findings of Kontizas et al. for NGC 2098. Presence of mass segregation in these clusters could be an imprint of star formation process as their ages are significantly smaller than their dynamical evolution time. Mean MF slope of γ=2.22±0.16\gamma = -2.22\pm0.16 derived for a sample of 25 young (100\le 100 Myr) dynamically unevolved LMC stellar systems provide support for the universality of IMF in the intermediate mass range 212M\sim 2-12 M_{\odot}.Comment: To appear in MNRA

    ENDO-PERIO LESION: A CASE REPORT

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    The pulp and periodontium have embryonic, anatomic and functional interrelationships. The simultaneous existence of pulpal problems and inflammatory periodontal disease can complicate diagnosis and treatment planning. This case report evaluates the efficacy of G-Bone graft in the management of vertical bone loss associated with an endo-perio lesion in a left mandibular first molar and second molar. A 40 year-old male patient with an endo-perio lesion in the left mandibular first and second molars was initially treated with endodontic therapy. Following the endodontic treatment, the defect was treated using G-Bone graft. At the end of 6 months, there was a gain in the clinical attachment level and reduction in probing depth. Radiographic evidence showed that there was a significant bony fill. Keywords: Endo - perio lesion; Vertical bone loss; G - Bone graft
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