Prompt emission polarimetry of Gamma Ray Bursts with ASTROSAT CZT-Imager

X-ray and Gamma-ray polarization measurements of the prompt emission of Gamma-ray bursts (GRBs) are believed to be extremely important for testing various models of GRBs. So far, the available measurements of hard X-ray polarization of GRB prompt emission have not significantly constrained the GRB models, particularly because of the difficulty of measuring polarization in these bands. The CZT Imager (CZTI) onboard {\em AstroSat} is primarily an X-ray spectroscopic instrument that also works as a wide angle GRB monitor due to the transparency of its support structure above 100 keV. It also has experimentally verified polarization measurement capability in the 100 $-$ 300 keV energy range and thus provides a unique opportunity to attempt spectro-polarimetric studies of GRBs. Here we present the polarization data for the brightest 11 GRBs detected by CZTI during its first year of operation. Among these, 5 GRBs show polarization signatures with $\gtrapprox$3$\sigma$, and 1 GRB shows $\>$2$\sigma$ detection significance. We place upper limits for the remaining 5 GRBs. We provide details of the various tests performed to validate our polarization measurements. While it is difficult yet to discriminate between various emission models with the current sample alone, the large number of polarization measurements CZTI expects to gather in its minimum lifetime of five years should help to significantly improve our understanding of the prompt emission.Comment: Accepted for Publication in ApJ ; a figure has been update

महाराष्ट्र की डोल जाल मात्स्यिकी

महाराष्ट्र की डोल जाल मात्स्यिक

Plastic menace faced by fishers of Satpati, Maharashtra

Small conical stationary bag nets (Bokshi) are operated by artisanal fishers mostly in creeks, with strong tidal currents in certain regions of Maharashtra. The net is set using wooden pole (Khunt) driven at creek bottom against the flood or ebb tide. At Satpati, Bokshi nets are operated in the near shore creek for about 16 days in a month at a rate of 2 hauls per day. Here, fishermen are concerned about the increasing quantity of plastic debris entering their nets during fishing operations adversely affecting their livelihood

Hatching of Olive ridley turtle twin hatchlings

A clutch of 126 olive ridley (Lepidochelys olivacea) turtle eggs was laid at Palapetty Beach, Thrissur District, Kerala on 15th January 2016 and relocated by members of the Kanyakumari Turtle NEWS Club to the hatchery at Palapetty. On 02nd March 2016, after 46 days of incubation, 58 hatchlings emerged from the nest unaided in the early morning. The nest was excavated three hours after emergence of the first hatchling, at which time 14 more hatchlings emerged from the exposed eggs including two pairs of twins (Table 1; for example see Figure 1) which emerged from the eggshells on their own. The hatchlings were transported to a holding tank 15min post-hatching. The twin hatchlings were unable to remain afloat and their movement on land was also impaired as they remained connected by the respective yolk sacs. The first pair of twin hatchlings died half an hour after hatching, while the second pair of twins survived for six hours. Four other hatchlings which emerged from the exposed eggs died before being introduced to the holding tank. The surviving hatchlings were released to sea approximately nine to thirteen hours after hatching

Anti-inflammatory activity of Ruta graveolens Linn on carrageenan induced paw edema in wistar male rats

Aqueous, ethanolic and methanolic extracts of Ruta graveolens were investigated for anti-inflammatory activity in carrageenan induced paw edema in wistar male rats, and compared to a positive controldrug, Voveran. These extracts were given (ip) in a concentration of 20 and 50 mg/kg b.w. before carrageenan injection. Methanolic extracts of R. graveolens with a concentration of 20 mg/kg b.w. and ethanolic extract with a concentration of 50 mg/kg b.w. showed maximum (90.9%) inhibition on carrageenan induced rat paw edema. The effect was significantly (P< 0.05) higher than that of the standard drug Voveran (72.72%). Methanol extract with a concentration of 50 mg/kg b.w. produced 81.81% inhibition, which was also high as compared to the standard drug. Ethanolic extract with a dose of 20 mg/kg b.w and the two doses of aqueous extract produce less percentage of inhibition as compared to the standard drug voveran

Automatic Identification System (AIS): An initiative in purse seine fisheries along Mumbai coast

Automatic Identification System (AIS) is a significant development in navigation safety since the introduction of RADAR. It was originally developed as a collision avoidance tool for commercial vessels to improve the helmsman’s information about his surrounding environment. AIS does this by continuously transmitting a vessels identity, position, speed and course along with other relevant information to all other AIS equipped vessels within range

The addition of fluoxetine to cognitive behavioural therapy for youth depression (YoDA-C): study protocol for a randomised control trial.

The aim of the Youth Depression Alleviation-Combined Treatment (YoDA-C) study is to determine whether antidepressant medication should be started as a first-line treatment for youth depression delivered concurrently with psychotherapy. Doubts about the use of medication have been raised by meta-analyses in which the efficacy and safety of antidepressants in young people have been questioned, and subsequent treatment guidelines for youth depression have provided only qualified support

Dynamic microtubules produce an asymmetric E-cadherin-Bazooka complex to maintain segment boundaries.

Distributing junctional components around the cell periphery is key for epithelial tissue morphogenesis and homeostasis. We discovered that positioning of dynamic microtubules controls the asymmetric accumulation of E-cadherin. Microtubules are oriented preferentially along the dorso-ventral axis in Drosophila melanogaster embryonic epidermal cells, and thus more frequently contact E-cadherin at dorso-ventral cell-cell borders. This inhibits RhoGEF2, reducing membrane recruitment of Rho-kinase, and increasing a specific E-cadherin pool that is mobile when assayed by fluorescence recovery after photobleaching. This mobile E-cadherin is complexed with Bazooka/Par-3, which in turn is required for normal levels of mobile E-cadherin. Mobile E-cadherin-Bazooka prevents formation of multicellular rosette structures and cell motility across the segment border in Drosophila embryos. Altogether, the combined action of dynamic microtubules and Rho signaling determines the level and asymmetric distribution of a mobile E-cadherin-Bazooka complex, which regulates cell behavior during the generation of a patterned epithelium

A variable magnetic disc wind in the black hole X-ray binary GRS 1915+105?

Context. GRS 1915+105 being one of the brightest transient black hole binaries (BHBs) in the X-rays offers a unique testbed for the study of the connection between accretion and ejection mechanisms in BHBs. In particular, this source can be used to study the accretion disc wind and its dependence on the state changes in BHBs.Aims. Our aim is to investigate the origin and geometry of the accretion disc wind in GRS 1915+105. This study will provide a basis for planning future observations with the X-ray Imaging Spectroscopy Mission (XRISM), and may also provide important parameters for estimating the polarimetric signal with the upcoming Imaging X-ray Polarimetry Explorer (IXPE).Methods. We analysed the spectra of GRS 1915+105 in the soft and hard chi classes using the high-resolution spectroscopy offered by Chandra HETGS. In the soft state, we find a series of wind absorption lines that follow a non-linear dependence of velocity width, velocity shift, and equivalent width with respect to ionisation, indicating a multiple component or stratified outflow. In the hard state we find only a faint Fe XXVI absorption line. We model the absorption lines in both the states using a dedicated magneto-hydrodynamic (MHD) wind model to investigate a magnetic origin of the wind and to probe the cause of variability in the observed line flux between the two states.Conclusions. The MHD disc wind model provides a good fit for both states, indicating the possibility of a magnetic origin of the wind. The multiple ionisation components of the wind are well characterised as a stratification of the same magnetic outflow. We find that the observed variability in the line flux between soft and hard states cannot be explained by photo-ionisation alone but is most likely due to a large (three orders of magnitude) increase in the wind density. We find the mass outflow rate of the wind to be comparable to the accretion rate, suggesting an intimate link between accretion and ejection processes that lead to state changes in BHBs

Perspectives and future vision for augmenting seafood export from India

India is bestowed with a long coastline of 8129 km, 0.5 million sq.km of continental shelf, 2.02 million sq.km of EEZ, and a catchable annual marine fishery potential of 4.41 million tons. India is the second largest fish-producing country in the world accounting for 7.56 percent of global production and 4th largest fish exporter. In 2021-22, India's total marine fish production stood at 3,05 million tons