Detecting cold gas at intermediate redshifts: GMRT survey using Mg II systems

Intervening HI 21-cm absorption systems at z > 1.0 are very rare and only 4 confirmed detections have been reported in the literature. Despite their scarcity, they provide interesting and unique insights into the physical conditions in the interstellar medium of high-z galaxies. Moreover, they can provide independent constraints on the variation of fundamental constants. We report 3 new detections based on our ongoing Giant Metrewave Radio Telescope (GMRT) survey for 21-cm absorbers at 1.10< z_abs< 1.45 from candidate damped Lyman_alpha systems. The 21-cm lines are narrow for the z_abs = 1.3710 system towards SDSS J0108-0037 and z_abs = 1.1726 system toward SDSS J2358-1020. Based on line full-width at half maximum, the kinetic temperatures are <= 5200 K and <=800 K, respectively. The 21-cm absorption profile of the third system, z_abs =1.1908 system towards SDSS J0804+3012, is shallow, broad and complex, extending up to 100 km/s. The centroids of the 21-cm lines are found to be shifted with respect to the corresponding centroids of the metal lines derived from SDSS spectra. This may mean that the 21-cm absorption is not associated with the strongest metal line component.Comment: 13 pages with 5 figures. Accepted for publication in ApJ

Contrast Interferometry Using Bose-Einstein Condensates to Measure h/m and the Fine Structure Constant

The kinetic energy of an atom recoiling due to absorption of a photon was measured as a frequency using an interferometric technique called ``contrast interferometry''. Optical standing wave pulses were used as atom-optical elements to create a symmetric three-path interferometer with a Bose-Einstein condensate. The recoil phase accumulated in different paths was measured using a single-shot detection technique. The scheme allows for additional photon recoils within the interferometer and its symmetry suppresses several random and systematic errors including those from vibrations and ac Stark shifts. We have measured the photon recoil frequency of sodium to $7$ppm precision, using a simple realization of this scheme. Plausible extensions should yield a sufficient precision to bring within reach a ppb-level determination of $h/m$ and the fine structure constant $\alpha$

Optical and Structural Modifications of γ irradiated Cr-39 Polymers

The UV-Visible absorption spectra of CR-39 polymer, unirradiated and irradiated to gamma radiation up to 500 kGy dose were studied. The development of new peaks, shifting of absorption bands and their broadening as a result of gamma irradiation were observed and analyzed. The values of optical constant like direct and indirect band gaps have been determined. The values of indirect band gap have been found to have lower values then the corresponding values of direct band gap. The increase in carbon conjugation length and size of carbon clusters has also been pointed out from the results of UV-Visible spectroscopy

Design of blended rolled edges for compact range main reflectors

A procedure to design blended rolled edge terminations for arbitrary rim shape compact range main reflectors is presented. The reflector may be center-fed or offset-fed. The design procedure leads to a reflector which has a continuous and smooth surface. This procedure also ensures small diffracted fields from the junction between the paraboloid and the blended rolled edge while satisfying certain constraints regarding the maximum height of the reflector and minimum operating frequency of the system. The prescribed procedure is used to design several reflectors and the performance of these reflectors is presented

Investigating relationship types for creating brand value for resellers

This study investigates different types of brand-reseller business relationships, in order to explain how a) real-time, b) collaborative and c) mutually beneficial relationships drive brand value creation in a competitive market. Using data collected from Indian reseller firms selling branded products, this paper extends our existing knowledge of different types of relationships useful for business-to-business marketing practitioners. Brand managers can use these three different types of business relationships to create superior brand value for resellers, thus improving their brands’ perceived competitiveness. Specifically, the findings show that brands that engage in real-time and collaborative relationships are regarded by resellers as having higher brand value in comparison to brands that only focus on mutually beneficial relationships