A revised estimate of the distance to the clouds in the Chamaeleon complex using the Tycho-Gaia Astrometric Solution

The determination of the distance to dark star-forming clouds is a key parameter to derive the properties of the cloud itself, and of its stellar content. This parameter is still loosely constrained even in nearby star-forming regions. We want to determine the distances to the clouds in the Chamaeleon-Musca complex and to explore the connection between these clouds and the large scale cloud structures in the galaxy. We use the newly estimated distances obtained from the parallaxes measured by the Gaia satellite and included in the Tycho-Gaia Astrometric Solution catalog. When known members of a region are included in this catalog we use their parallaxes to infer the distance to the cloud. Otherwise, we analyze the dependence of the color excess on the distance of the stars and look for a turn-on of this excess, which is a proxy of the position of the front-edge of the star-forming cloud. We are able to measure the distance to the three Chamaeleon clouds. The distance to Chamaeleon I is 179 pc, 20 pc further away than previously assumed. The Chamaeleon II cloud is located at the distance of 181 pc, which agrees with previous estimates. We are able to measure for the first time a distance to the Chamaeleon III cloud of 199 pc. Finally, the distance of the Musca cloud is smaller than 603 pc. These estimates do not allow us to distinguish between the possibility that the Chamaeleon clouds are part of a sheet of clouds parallel to the galactic plane, or perpendicular to it. Gaia Data Release 2 will allow us to put more stringent constraints on the distances to these clouds by giving us access to parallax measurements for a larger number of members of these regions.Comment: Accepted for publication on A&A. Abstract shortened for arxiv constraint

Gaia view of low-mass star formation

Understanding how young stars and their circumstellar disks form and evolve is key to explain how planets form. The evolution of the star and the disk is regulated by different processes, both internal to the system or related to their environment. The former include accretion of material onto the central star, wind emission, and photoevaporation of the disk due to high-energy radiation from the central star. These are best studied spectroscopically, and the distance to the star is a key parameter in all these studies. Here we present new estimates of the distance to a complex of nearby star-forming clouds obtained combining TGAS distances with measurement of extinction on the line of sight. Furthermore, we show how we plan to study the effects of the environment on the evolution of disks with Gaia, using a kinematic modelling code we have developed to model young star-forming regions.Comment: 4 pages, 1 figure. To appear in the Proceedings of IAU Symposium 330: Astrometry and Astrophysics in the Gaia Sk

Efficient Intrusion Detection Model Using Ensemble Methods

Ensemble method or any combination model train multiple learners to solve the classification or regression problems, not by simply ordinary learning approaches that can able to construct one learner from training data rather construct a set of learners and combine them. Boosting algorithm is one of the most important recent developments in the area of classification methodology. Boosting belongs to a family of algorithms that has the capability to convert a group of weak learners to strong learners. Boosting works in a sequential manner by adding a classification algorithm to the next updated weight of the training samples by doing the majority voting technique of the sequence of classifiers. The boosting method combines the weak models to produce a powerful one and reduces the bias of the combined model. AdaBoost algorithm is the most influential algorithm that efficiently combines the weak learners to generate a strong classifier that could be able to classify a training data with better accuracy. AdaBoost differs from the current existing boosting methods in detection accuracy, error cost minimization, computational time and detection rate. Detection accuracy and computational cost are the two main metrics used to analyze the performance of AdaBoost classification algorithm. From the simulation result, it is evident that AdaBoost algorithm could able to achieve high detection accuracy with less computational time, and minimum cost compared to a single classifier. We have proposed a predictive model to classify normal class and attack class and an online inference engine is being imposed, either to allow or deny access to a network

Antibacterial Activity of Some Indian Medicinal Plants

The preliminary phytochemical study and in vitro antibacterial activity of the ethanolic extracts of three plants having ethnomedicinal uses collected from tribal belt of Orissa, India, viz. Litsea glutinosa L.: Lauraceae (LG), Vitex peduncularis W.: Verbenaceae (VP), Elephantopus scaber L.: Asteraceae (ES) were investigated. The preliminary phytochemical analysis of the extracts revealed the presence of carbohydrate, tannin, alkaloid in LG, tannin, flavonoid, saponin, alkaloid in VP and flavonoid, saponin, steroid, alkaloid, glycoside in ES. The extracts were subjected for screening of in vitro antibacterial activity against selected major urinary tract infection (UTI) causing pathogens viz. Staphylococcus aureus, Pseudomonas aeruginosa, Proteus mirabilis, Enterococcus faecalis and Escherichia coli at the concentrations of 500 and 250 µg/ml by disc diffusion assay method. The results of antibacterial activity revealed that all the extract showed good inhibitory activity against all the tested pathogens and the ES extract showed comparative by better activity than the other extracts. The activity of the extract were compared with standard antibiotics

Long-term evolution of FU Orionis objects at infrared wavelengths

We investigate the brightness evolution of 7 FU Orionis systems in the 1-100 micrometer wavelength range using data from the Infrared Space Observatory (ISO). The ISO measurements were supplemented with 2MASS and MSX observations performed in the same years as the ISO mission (1995-98). The spectral energy distributions (SEDs) based on these data points were compared with earlier ones derived from the IRAS photometry as well as from ground-based observations carried out around the epoch 1983. In 3 cases (Z CMa, Parsamian 21, V1331 Cyg) no difference between the two epochs was seen within the measurement uncertainties. V1057 Cyg, V1515 Cyg and V1735 Cyg have become fainter at near-infrared wavelengths while V346 Nor has become slightly brighter. V1057 Cyg exhibits a similar flux change also in the mid-infrared. At lambda >= 60 micrometer most of the sources remained constant; only V346 Nor seems to fade. Our data on the long-term evolution of V1057 Cyg agree with the model predictions of Kenyon & Hartmann (1991) and Turner et al. (1997) at near- and mid-infrared wavelengths, but disagree at lambda > 25 micrometer. We discuss if this observational result at far-infrared wavelengths could be understood in the framework of the existing models.Comment: 9 pages, 3 figures, to be published in Astronomy & Astrophysic

The intricate Galaxy disk: velocity asymmetries in Gaia-TGAS

We use the Gaia-TGAS data to compare the transverse velocities in Galactic longitude (coming from proper motions and parallaxes) in the Milky Way disk for negative and positive longitudes as a function of distance. The transverse velocities are strongly asymmetric and deviate significantly from the expectations for an axisymmetric Galaxy. The value and sign of the asymmetry changes at spatial scales of several tens of degrees in Galactic longitude and about 0.5 kpc in distance. The asymmetry is statistically significant at 95% confidence level for 57% of the region probed, which extends up to ~1.2 kpc. A percentage of 24% of the region studied shows absolute differences at this confidence level larger than 5 km/s and 7% larger than 10 km/s. The asymmetry pattern shows mild variations in the vertical direction and with stellar type. A first qualitative comparison with spiral arm models indicates that the arms are unlikely to be the main source of the asymmetry. We briefly discuss alternative origins. This is the first time that global all-sky asymmetries are detected in the Milky Way kinematics, beyond the local neighbourhood, and with a purely astrometric sample.Comment: Accepted for publication in A&A Letter

Ethnobotanical Exploration of Malkangiri District of Orissa, India

The association of man with the neighborhood flora starts with human civilization. Besides food, feed clothes and shelter, plants are important source of drugs. These plants or its parts therefore used either directly or after processing by the native people against various diseases, disorders and ailments. A survey was conducted on the tribal district of Malkangiri of Orissa to identify and record various ethno medicinally important plants and their medicinal uses. In the present investigation there are 134 species of plants belong to 69 families and 128 genera are recorded and used in various ailments by different tribes of Malkangiri district of Orissa

Identification of new transitional disk candidates in Lupus with Herschel

New data from the Herschel Space Observatory are broadening our understanding of the physics and evolution of the outer regions of protoplanetary disks in star forming regions. In particular they prove to be useful to identify transitional disk candidates. The goals of this work are to complement the detections of disks and the identification of transitional disk candidates in the Lupus clouds with data from the Herschel Gould Belt Survey. We extracted photometry at 70, 100, 160, 250, 350 and 500 $\mu$m of all spectroscopically confirmed Class II members previously identified in the Lupus regions and analyzed their updated spectral energy distributions. We have detected 34 young disks in Lupus in at least one Herschel band, from an initial sample of 123 known members in the observed fields. Using the criteria defined in Ribas et al. (2013) we have identified five transitional disk candidates in the region. Three of them are new to the literature. Their PACS-70 $\mu$m fluxes are systematically higher than those of normal T Tauri stars in the same associations, as already found in T Cha and in the transitional disks in the Chamaeleon molecular cloud. Herschel efficiently complements mid-infrared surveys for identifying transitional disk candidates and confirms that these objects seem to have substantially different outer disks than the T Tauri stars in the same molecular clouds.Comment: Accepted for publication in A&A. 16 pages, 9 figures, 7 table