Radio galaxies - the TeV challenge

Over the past decade, our knowledge of the \gamma-ray sky has been revolutionized by ground- and space-based observatories by detecting photons up to several hundreds of tera-electron volt (TeV) energies. A major population of the $\gamma$-ray bright objects are active galactic nuclei (AGN) with their relativistic jets pointed along our line-of-sight. Gamma-ray emission is also detected from nearby mis-aligned AGN such as radio galaxies. While the TeV-detected radio galaxies (TeVRad) only form a small fraction of the \gamma-ray detected AGN, their multi-wavelength study offers a unique opportunity to probe and pinpoint the high-energy emission processes and sites. Even in the absence of substantial Doppler beaming TeVRad are extremely bright objects in the TeV sky (luminosities detected up to 10^{45} erg/s), and exhibit flux variations on timescales shorter than the event-horizon scales (flux doubling timescale less than 5 minutes). Thanks to the recent advancement in the imaging capabilities of high-resolution radio interferometry (millimeter very long baseline interferometry, mm-VLBI), one can probe the scales down to less than 10 gravitational radii in TeVRad, making it possible not only to test jet launching models but also to pinpoint the high-energy emission sites and to unravel the emission mechanisms. This review provides an overview of the high-energy observations of TeVRad with a focus on the emitting sites and radiation processes. Some recent approaches in simulations are also sketched. Observations by the near-future facilities like Cherenkov Telescope Array, short millimeter-VLBI, and high-energy polarimetry instruments will be crucial for discriminating the competing high-energy emission models.Comment: Invited review article, submitted to Galaxies; 28 pages, 8 figure

S5 0716+714 : GeV variability study

The GeV observations by Fermi-LAT give us the opportunity to characterize the high-energy emission (100 MeV - 300 GeV) variability properties of the BL Lac object S5 0716+714. In this study, we performed flux and spectral analysis of more than 3 year long (August 2008 to April 2012) Fermi-LAT data of the source. During this period, the source exhibits two different modes of flux variability with characteristic timescales of ~75 and ~140 days, respectively. We also notice that the flux variations are characterized by a weak spectral hardening. The GeV spectrum of the source shows a clear deviation from a simple power law, and is better explained by a broken power law. Similar to other bright Fermi blazars, the break energy does not vary with the source flux during the different activity states. We discuss several possible scenarios to explain the observed spectral break.Comment: 21 pages, 10 figures, Accepted for publication in Advances in Space Research journa

Characteristic and Medicinal Properties of Yellow Flowers in Sangam Literature

The beliefs, customs, culture, civilization of the people who lived ancient are based on love, heroism, etc. When Sangam literature mentions the two discriminating themes of internal and external life, the relationship and friendship they had with people, birds, animals, plants, and flowers can be well known. All these are shown in natural background. In this way, flowers become prominent. Flowers, which are a symbol of Tamil culture, takes special place from birth to death. This article examines the beauty and uniqueness of yellow flowers such as Avirai, Gongam, Chenpakam, Kannai, Vengai etc. and the medicinal properties of these flowers through Sangam literary songs

Dynamic Vs Static Term-Expansion using Semantic Resources in Information Retrieval

Information Retrieval in a Telugu language is upcoming area of research. Telugu is one of the recognized Indian languages. We present a novel approach in reformulating item terms at the time of crawling and indexing. The idea is not new, but use of synset and other lexical resources in Indian languages context has limitations due to unavailability of language resources. We prepared a synset for 1,43,001 root words out of 4,83,670 unique words from training corpus of 3500 documents during indexing. Index time document expansion gave improved recall ratio, when compared to base line approach i.e. simple information retrieval without term expansion at both the ends. We studied the effect of query terms expansion at search time using synset and compared with simple information retrieval process without expansion, recall is greatly affected and improved. We further extended this work by expanding terms in two sides and plotted results, which resemble recall growth. Surprisingly all expansions are showing improvement in recall and little fall in precision. We argue that expansion of terms at any level may cause inverse effect on precision. Necessary care is required while expanding documents or queries with help of language resources like Synset, WordNet and other resources

Performances Based Study On High Strengh Concrete Using Fiber As The Replacement

Processed sand is increasingly used as an alternative. With the prohibition of sand mining in several states and the increasing demand for river sand for construction work, many civil engineers have expressed the need to promote the use of manufactured sand in the construction industry. Manufactured sand is reportedly used extensively around the world and technicians at major projects around the world insist on the mandatory use of manufactured sand due to its constant gradation and no impurities. Ordinary concrete lacks the required strength and durability often required for large concrete structures such as tall buildings, bridges, and structures under severe exposure conditions. Due to the prosperous construction activities, natural sand has become scarce due to excessive unscientific methods of extraction from the river bed. For these reasons, it is necessary to produce improved concrete with high strength, using suitable materials. This article demonstrates the effective use of the product fibers and M-sand in high-strength concrete

Comparative seedling morphology of four species of Sida (Malvaceae) from Tripura, India and their taxonomic implications

Comparative seedling morphology of four Sida species occurring in Tripura were investigated. Seedling characters (germination pattern, position of cotyledon, hypocotyl, epicotyl and paracotyledon and eophylls development) were found to be important and promising from the taxonomic as well as evolutionary point of view. These characters provide important diagnostic character of the species of the genus. Phenogram based on UPGMA method has been prepared and correlation between the characters of seedling of four Sida species were studied

Seed and seedling morphology of some medicinal plants of family Malvaceae in Tripura, North-east India

Plants in their juvenile stage possess some important characters which are very important and promising from the taxonomic as well as evolutionary point of view. Seed and Seedling morphology of ten species of Malvaceae has been investigated on the basis of their germination pattern, position of cotyledon, hypocotyl, epicotyl and paracotyledon and eophylls development. An artificial key has been constructed for easier identification of plants in their juvenile stage. Phenogram has been made by using UPGMA analysis to investigate the correlation between the investigated taxa