Evidence of a counterrotating core in the Large Magellanic Cloud

Stellar radial velocity in the central region of the Large Magellanic Cloud (LMC) is used to estimate the radial velocity curve along various position angles (PA) including the line of nodes (LON). The central part of the radial velocity profile, along the LON, shows a V-shaped profile - a clear indication of counterrotation. The counterrotating region and the secondary bar have similar location and PA. The origin of the counter-rotating core could be internal(secondary bar) or external(accretion). To explain the observed velocity profile, we propose the existence of two disks in the inner LMC, with one counterrotating. This two disk model is found to match the HI velocities as well. Two disks with different LON and velocity profiles can create regions which are kinematically and spatially separated. Predicted such locations are found to match the observed locations where the HI clouds are found to have two velocities.Comment: 12 pages including 3 figures, to appear in ApJ Letter

Splenectomy and proximal lieno-renal shunt in a factor five deficient patient with extra-hepatic portal vein obstruction

BACKGROUND: The clinico-surgical implication and successful management of a rare case of factor five (V) deficiency with portal hypertension and hypersplenism due to idiopathic extra-hepatic portal venous obstruction is presented. CASE PRESENTATION: A 16-year old boy had gastro-esophageal variceal bleeding, splenomegaly and hypersplenism. During preoperative workup prolonged prothrombin time and activated partial thromboplastin time were detected, which on further evaluation turned out to be due to factor V deficiency. Proximal lieno-renal shunt and splenectomy were successfully performed with transfusion of fresh frozen plasma during and after the surgical procedure. At surgery there was no excessive bleeding. The perioperative course was uneventful and the patient is doing well on follow up. CONCLUSION: Surgical portal decompressive procedures can be safely undertaken in clotting factor deficient patients with portal hypertension if meticulous surgical hemostasis is achieved at operation and the deficient factor is adequately replaced in the perioperative period

Estimates of precipitable water vapour from GPS data over the Indian subcontinent

Water vapour plays a dominant role in the high-energy thermodynamics of the atmosphere, notably, the genesis of storm systems. However, its distribution is difficult to resolve by conventional means, since water vapour exhibits very high spatial and temporal variability. The growing networks of continuously operating GPS systems, however, offer the possibility of estimating the integrated water vapour (IWV) or, equivalently precipitable water vapour (PW). These estimates constitute critical inputs in operational weather forecasting and fundamental research to model atmospheric storm systems, atmospheric chemistry, and the hydrological cycle. This paper presents the results of IWV estimates from GPS data from continuously operating GPS stations established by C-MMACS at Bangalore, Kodaikanal, Hanle and Shillong over the 3-year period (2001-2003). These are the first results of such an endeavor, towards the study of PW at four different geographical locations in the Indian subcontinent

Aerosol number size distribution measurements at Hanle, a free tropospheric high-altitude site in Western Himalayas

Aerosol characteristics over the high altitude stations, akin to pristine and free conditions are important to understand the background aerosol features against which polluted and urban environments could be compared. In addition it is also important to monitor the changes brought about by the large-scale processes, which result in lofting and transporting of aerosols from different source regions to higher altitude levels. Moreover, these aerosols have a significant role in modifying clouds especially cold clouds. The availability of significant amount of solar UV radiation at these altitudes, along with water vapour and OH, if present, makes these regions conducive for formation of new particles from gas phase reaction products involving precursors of natural or anthropogenic origin. Such processes play a significant role in modulating the size distribution of free tropospheric aerosols and hence their radiative impacts. In this work, aerosol number size distribution measurements carried out from a high altitude free tropospheric Himalayan location, Hanle (32.78°N, 78.96°E, 4530 m amsl) during the period from May through December 2010 are examined. The monthly mean total number concentration (N_t) increased from May (614 ± 188 cm^-3) to October (1498 ± 792 cm^-3) and decreased slightly through December (1158 ± 470 cm^-3). Fine mode aerosols (size < 100nm) contributed mostly to the total number concentration. The fractional contribution of the fine mode aerosols to the total number concentration, showed a clear increasing trend from May (~ 0.57) to December (~ 0.81). The number size distribution, which remained unimodal in May, June months with a mode in accumulation size range (around 100nm), changed to a bimodal distribution subsequently with a mode in the nucleation size range (< 25nm), indicating the possibility of new particle formation. The results are discussed in light of the possible association between the variation of the aerosol number concentration to long-range transport and thermally driven mesoscale processes such as mountain/valley winds

Columnar aerosol extinction characteristics: measurements from a free-tropospheric observatory in Western-Himalayas

Continuous measurements of spectral aerosol optical depths (AOD) were made over a very high altitude aerosol observatory at Hanle (32.76°N, 78.95°E, 4520 m amsl), during the summer and autumn of 2009 and 2010, by using a 10-channel multi-wavelength radiometer (MWR). The results depicted very low values of AOD (with a mean for the measurement period as ~ 0.071 ± 0.003 at 500 nm), but with a spectral dependence that changed with the months from ~ 0.8 to 1.3, with a mean value of ~ 1.01 ± 0.06. The AODs though were in general comparable to those seen over pristine Antarctic environments, are quite significant when we consider the altitude of the station. The details are presented

Black carbon aerosol over a high altitude (~ 4.52 km) station in western Indian Himalayas

Continuous measurements of mass concentration of Black Carbon (BC) aerosols, measured from a high altitude (~ 4.5 km above msl) location, Hanle (32.78°N, 78.95°E) in the western Himalayas, during August 2009 to July 2010 have been examined. The day-to-day variations in BC mass concentration (M_B) were rather subdued in winter months while quite conspicuous during the spring months. It showed a well defined annual cycle with a maximum (109 ± 78 ng m^-3) during spring and minimum during the winter (66 ± 62 ng m^-3) season with an annual average M_B of 78 ± 64 ng m^-3. Examining the frequency distribution, it was found that 64 % of the values were below annual mean M_B showing a rather pristine nature for this near free tropospheric region. Trajectory clustering and concentration weighted trajectory (CWT) analysis indicated that, most of the year, the site is influenced from the advection from west and south west Asian locations and only for a small period from the Indo-Gangetic Plains (IGP). The observations are compared with other high altitude measurements, over the globe in general and around the Himalayan region

COSMOGRAIL: Measuring Time Delays of Gravitationally Lensed Quasars to Constrain Cosmology

COSMOGRAIL is a long-term programme for the photometric monitoring of gravitationally lensed quasars. It makes use of several medium-size telescopes to derive long and well-sampled light curves of lensed quasars, in order to measure the time delays between the quasar images. These delays directly relate to the Hubble constant H0, without any need for secondary distance calibrations. COSMOGRAIL was initiated in 2004, and has now secured almost a decade of data, resulting in cosmological constraints that are very complementary to other cosmological probes