Intra-night Optical Variability of Luminous Radio Quiet QSOs

In the present paper we report the detection of intra-night variability in some of the RQQSOs and one LDQ. To study intra-night variability, we carried out photometric monitoring of seven RQQSOs and one LDQ in Johnson V-passband using 1.2 meter optical/IR telescope at Gurushikhar, Mount Abu, India. Observations were made in nine nights during the first half of the year 2000; seven RQQSOs: 0748+291, 0945+438, 1017+280, 1029+329, 1101+319, 1225+317, 1252+020 and one LDQ: 1103-006 were observed. RQQSOs 0748+291, 1225+317 and LDQ 1103-006 have shown existence of intra-night variations. In the case of 1017+280 (RQQSO) there is indication of intra-night variation in one night where as the observations in another night do not show convincingly the existence of intra-night variability. RQQSOs 0945+438, 1029+329, 1101+319 and 1252+020 have not shown any intra-night variations. We compiled intra-night variability data for radio-loud and radio-quiet AGNs from the literature for statistical analysis. It is found that a good fraction of radio-quiet AGNs show intra-night variations with the maximum amplitude of variation being about 10%. On the other hand blazars show at times intra-night flux variability up to 100%. In case of radio-loud AGNs (excluding blazars), maximum amplitude of intra-night variation lies between the variability amplitude of radio-quiet AGNs and blazars i.e. the flux variation is close to 50%. The results indicate that the energy generation mechanism and the environment around the central engine in different classes of AGNs may be similar, if not identical. The standard model for radio-loud AGNs, where shocks are propagating down relativistic jet or models based on disturbances in accretion disks can also explain the micro-variability in RQQSOs.Comment: 12 pages, 12 figures, Accepted for publication in A & A, uses aa.cl

Geo-Metallurgical Studies of Rampura Agucha Deposit

Rampura Agucha deposit which is the 5 th largest deposit in the world in terms of the reserves and 3'd largest in terms of metal production, is also one of the most complex deposit in the world in terms of its textural characteri-stics, due to its highly deformed nature. The paper details the results of Geo-metallurgical studies for identification of domains within the deposit with similar textural characteristics and their correlation with actual plant performance. As recovery performance of the valuable minerals directly impacts the profitability, the plant metallurgist would be very much interested in improvement of recovery performance of lead / zinc and the inputs of process mineralogy for understanding metallurgical process are very important and the insights provided by process mineralogy in understanding and improving the recovery processes are described

Collapse Dynamics of a Star of Dark Matter and Dark Energy

In this work, we study the collapse dynamics of an inhomogeneous spherically symmetric star made of dark matter (DM) and dark energy (DE). The dark matter is taken in the form of a dust cloud while anisotropic fluid is chosen as the candidate for dark energy. It is investigated how dark energy modifies the collapsing process and is examined whether dark energy has any effect on the Cosmic Censorship Conjecture. The collapsing star is assumed to be of finite radius and the space time is divided into three distinct regions $\Sigma$ and $V^{\pm}$, where $\Sigma$ represents the boundary of the star and $V^{-}(V^{+})$ denotes the interior (exterior) of the star. The junction conditions for matching $V^{\pm}$ over $\Sigma$ are specified. Role of Dark energy in the formation of apparent horizon is studied and central singularity is analyzed.Comment: 13 page

Naked Singularities in Higher Dimensional Szekeres Space-time

In this paper we study the quasi-spherical gravitational collapse of (n+2) dimensional Szekeres space-time. The nature of the central shell focusing singularity so formed is analyzed by studying both the radial null and time-like geodesic originated from it. We follow the approach of Barve et al to analyze the null geodesic and find naked singularity in different situations.Comment: 11 Latex Pages, 4 figures, RevTex styl

NRF2 promotes urothelial cell response to bacterial infection by regulating reactive oxygen species and RAB27B expression

Uropathogenic Escherichia coli (UPEC) cause urinary tract infections (UTIs) by invading urothelial cells. In response, the host mounts an inflammatory response to expel bacteria. Here, we show that the NF-E2-related factor 2 (NRF2) pathway is activated in response to UPEC-triggered reactive oxygen species (ROS) production. We demonstrate the molecular sequence of events wherein NRF2 activation in urothelial cells reduces ROS production, inflammation, and cell death, promotes UPEC expulsion, and reduces the bacterial load. In contrast, loss of NRF2 leads to increased ROS production, bacterial burden, and inflammation, both in vitro and in vivo. NRF2 promotes UPEC expulsion by regulating transcription of the RAB-GTPase RAB27B. Finally, dimethyl fumarate, a US Food and Administration-approved NRF2 inducer, reduces the inflammatory response, increases RAB27B expression, and lowers bacterial burden in urothelial cells and in a mouse UTI model. Our findings elucidate mechanisms underlying the host response to UPEC and provide a potential strategy to combat UTIs

First record of Pyramodon lindas (Markle and Olney, 1990) (Ophidiforms: Carapidae) from Indian Seas

Background: The present report is the first record of the Pyramodon lindas (Markle and Olney, Bull Mar Sci 47: 269-410, 1990) from India waters. A specimen of Pyramodon lindas measuring 483 mm total length was obtained from Tuticorin of Gulf of Mannar which is the largest specimen of so far recorded. Results: The Pyramodon lindas measured 483 mm in TL, 85 mm in Head length, 18.1 mm in snout length. Body elongate, compressed to round and eel like, supramaxilla absent, anal fin origin advanced. The specimen was deposited in the National Biodiversity Museum at the Central Marine Fisheries Research Institute, Kochi (GB.28.3.3.1) Detailed mophometric and meristic characters described and discussed. Conclusion: The Pyramodon lindas reported in the present study makes the total species reported from India as four in family Carapidae. The other reports were Carapus homei (Richardson, 1846), Pyramodon punctatum (Regan, 1914), Carapus margaritiferae (Rendahl, 1921) Brotula multibarbata Temmink & Schlegel, 1846 Antennarius hispidus (Bloch & Schneider, 1801)

Higher dimensional dust collapse with a cosmological constant

The general solution of the Einstein equation for higher dimensional (HD) spherically symmetric collapse of inhomogeneous dust in presence of a cosmological term, i.e., exact interior solutions of the Einstein field equations is presented for the HD Tolman-Bondi metrics imbedded in a de Sitter background. The solution is then matched to exterior HD Scwarschild-de Sitter. A brief discussion on the causal structure singularities and horizons is provided. It turns out that the collapse proceed in the same way as in the Minkowski background, i.e., the strong curvature naked singularities form and that the higher dimensions seem to favor black holes rather than naked singularities.Comment: 7 Pages, no figure

Uranium series inequilibrium and the geochemical processes occurring on the surface of coastal sediments

Remarkable anomaly has been observed between U238 and U234 in the marine environment by a number of workers in the field. But little information is available regarding the U238^ U235 and U^^^ activities in coastal sediments. The present work deals with the ratio of the activities of U23</U238 and Ui35/U238 from the coastal sediments of the west coast of India from Bombay (19°N, 73°E) to the southern tip of India up to Kottilppad near Manavalakurichi (8°N, 77°E) in the monazite bearing area of Kerala State. The sediment samples are leached with ammonium carbonate solution so as not to attack the mineral core of the sediment and to get the leachable uranium activities from the surface of the particles. In all the sediment samples U234 activity is about 12 to 14% higher than the equilibrium value indicating that there is disequilibrium between U^^B and U^34. The U235/U238 activity ratios lie in the range of 0.045 to 0.048 thereby showing that there is no significant fractionation between 0^38 and U235