The Thirty Meter Telescope International Observatory facilitating transformative astrophysical science

The next major advancement in astronomy and cosmology will be driven by deep observations using very sensitive telescopes with high spatial and spectral resolution capabilities. An international consortium of astronomers, including Indian astronomers are building the Thirty Meter Telescope to achieve breakthroughs in different areas of astronomy starting from studies of the solar system to that of the early universe. This article provides a brief overview of the telescope, science objectives and details of the first light instruments.Comment: 10 page

Effect of humidity on transonic flow

An experimental investigation of the effects of humidity-induced condensation on shock/boundary-layer interaction has been conducted in a transonic wind-tunnel test. The test geometry considered was a wall-mounted bump model inserted in the test section of the wind tunnel. The formation of a λ-shape condensation shock wave was shown from schlieren visualization and resulted in a forward movement of the shock wave, reduced shock wave strength, and reduced separation. Empirical correlations of the shock wave strength and humidity/dew point temperature were established. For humidity levels below 0.15 or a dew point temperature of 268 K, the effect of humidity was negligible. The unsteady pressure measurements showed that if a condensation shock wave formed and interacted with a main shock wave, the flow becomes unsteady with periodic flow oscillations occurring at 720 Hz

Status survey of scleractinian corals at Long Island and adjoining areas of Middle Andaman Archipelago

1556-1566Long Island and its adjoining islands of Middle Andaman archipelago are mostly covered by mangrove habitat while the eastern coastal parts of the islands are with scattered fringing reef in the continental shelf region. A total of 253 species of scleractinian corals were recorded from four islands such as Long, Guitar, Round and North Passage with the average species diversity of 3.18 and live cover of 25.28 %. Globally recorded threatened 42 species of scleractinians were recorded from these study areas. The regional occurrence of the species revealed that 32.41 % scleractinian were common and 24.90 % corals were rare. Long Island harbors 29.42 % of scleractinian coral species of Andaman and Nicobar Islands with optimum diversity (H'=4.35) especially in the eastern and south-eastern coast. The present paper focused on the status survey of scleractinian corals from these areas to monitor the health status in Middle Andaman region of Andaman and Nicobar Islands

New records of Opisthobranchs (Mollusca: Gastropoda) from Gulf of Mannar, India

1508-1515An extensive survey was carried out to explore the Opisthobranchs and associated faunal community in and around the Gulf of Mannar Marine Biosphere Reserve (GoMBR), South-east coast of India, resulted eight species (Aplysia juliana, Goniobranchus annulatus, Goniobranchus cavae, Goniobranchus collingwoodi, Goniobranchus conchyliatus, Dendrodoris albobrunnea, Elysia nealae, and Thecacera pacifica) which are new records to Indian coastal waters and GoMBR respectively. The detailed description, distribution and morphological characters are presented in this manuscript

ReverseCloak: A Reversible Multi-level Location Privacy Protection System

With the fast popularization of mobile devices and wireless networks, along with advances in sensing and positioning technology, we are witnessing a huge proliferation of Location-based Services (LBSs). Location anonymization refers to the process of perturbing the exact location of LBS users as a cloaking region such that a user's location becomes indistinguishable from the location of a set of other users. However, existing location anonymization techniques focus primarily on single level unidirectional anonymization, which fails to control the access to the cloaking data to let data requesters with different privileges get information with varying degrees of anonymity. In this demonstration, we present a toolkit for ReverseCloak, a location perturbation system to protect location privacy over road networks in a multi-level reversible manner, consisting of an 'Anonymizer' GUI to adjust the anonymization settings and visualize the multilevel cloaking regions over road network for location data owners and a 'De-anonymizer' GUI to de-anonymize the cloaking region and display the reduced region over road network for location data requesters. With the toolkit, we demonstrate the practicality and effectiveness of the ReverseCloak approach

Multiphase Plasma in Sub-Damped Lyman Alpha Systems: A Hidden Metal Reservoir

We present a VLT/UVES spectrum of a proximate sub-damped Lyman-alpha (sub-DLA) system at z=2.65618 toward the quasar Q0331-4505 (z_qso=2.6785+/-0.0030). Absorption lines of O I, Si II, Si III, Si IV, C II, C III, C IV, Fe II, Al II, and O VI are seen in the sub-DLA, which has a neutral hydrogen column density log N(H I)=19.82+/-0.05. The absorber is at a velocity of 1820+/-250 km/s from the quasar; however, its low metallicity [O/H]=-1.64+/-0.07, lack of partial coverage, lack of temporal variations between observations taken in 2003 and 2006, and non-detection of N V imply the absorber is not a genuine intrinsic system. By measuring the O VI column density and assuming equal metallicities in the neutral and ionized gas, we determine the column density of hot ionized hydrogen in this sub-DLA, and in two other sub-DLAs with O VI drawn from the literature. Coupling this with determinations of the typical amount of warm ionized hydrogen in sub-DLAs, we confirm that sub-DLAs are a more important metal reservoir than DLAs, in total comprising at least 6-22% of the metal budget at z~2.5.Comment: 5 pages, 3 color figures, accepted for publication in ApJ

Detection of CMB-Cluster Lensing using Polarization Data from SPTpol

We report the first detection of gravitational lensing due to galaxy clusters using only the polarization of the cosmic microwave background (CMB). The lensing signal is obtained using a new estimator that extracts the lensing dipole signature from stacked images formed by rotating the cluster-centered Stokes QU map cutouts along the direction of the locally measured background CMB polarization gradient. Using data from the SPTpol 500  deg² survey at the locations of roughly 18 000 clusters with richness λ ≥ 10 from the Dark Energy Survey (DES) Year-3 full galaxy cluster catalog, we detect lensing at 4.8σ. The mean stacked mass of the selected sample is found to be (1.43±0.40)×10¹⁴14M⊙ which is in good agreement with optical weak lensing based estimates using DES data and CMB-lensing based estimates using SPTpol temperature data. This measurement is a key first step for cluster cosmology with future low-noise CMB surveys, like CMB-S4, for which CMB polarization will be the primary channel for cluster lensing measurements

Two new records of Dendronephthya octocorals (Family: Nephtheidae) from Andaman and Nicobar Islands, India

343-348An extensive survey to explore the variety and distribution of octocorals and associated faunal community in and around the Andaman and Nicobar Islands yielded two species (Dendronephthya mucronata and D. savignyi), which is new zoogeographical record in India. The elaborate description, distribution and morphological characters are presented in this paper. The literature reveals that so far 55 species of Dendronephthya octocorals have been recorded from India

Bend and splay elastic constants of a discotic nematic

We report the dielectric constants and the splay and bend elastic constants of hexan-dodecanoyloxy truxene in the nematic phase, which occurs between two columnar phases. The dielectric anisotropy is positive. The elastic constants are ∼10−7 dyne, which is of the same order as for nematics of rod-like molecules. Further, k33 > k11, probably as a consequence of the columnar short range order in the medium