Bright solitons in asymmetrically trapped Bose-Einstein condensate

We study the dynamics of bright solitons in a Bose-Einstein condensate (BEC) confined in a highly asymmetric trap. While working within the f ramework of a variational approach we carry out the stability analysis o f BEC solitons against collapse. When the number of atoms in the soliton exceeds a critical number $N_c$, it undergoes the so called primary col lapse. We find an analytical expression for $N_c$ in terms of appropriat e experimental quantities that are used to produce and confine the conde nsate. We further demonstrate that, in the geometry of the problem consi dered, the width of the soliton varies inversely as the number of consti tuent atoms.Comment: 5 pages, 1 figure

Visibility based angular power spectrum estimation in low frequency radio interferometric observations

We present two estimators to quantify the angular power spectrum of the sky signal directly from the visibilities measured in radio interferometric observations. This is relevant for both the foregrounds and the cosmological 21-cm signal buried therein. The discussion here is restricted to the Galactic synchrotron radiation, the most dominant foreground component after point source removal. Our theoretical analysis is validated using simulations at 150 MHz, mainly for GMRT and also briefly for LOFAR. The Bare Estimator uses pairwise correlations of the measured visibilities, while the Tapered Gridded Estimator uses the visibilities after gridding in the uv plane. The former is very precise, but computationally expensive for large data. The latter has a lower precision, but takes less computation time which is proportional to the data volume. The latter also allows tapering of the sky response leading to sidelobe suppression, an useful ingredient for foreground removal. Both estimators avoid the positive bias that arises due to the system noise. We consider amplitude and phase errors of the gain, and the w-term as possible sources of errors . We find that the estimated angular power spectrum is exponentially sensitive to the variance of the phase errors but insensitive to amplitude errors. The statistical uncertainties of the estimators are affected by both amplitude and phase errors. The w-term does not have a significant effect at the angular scales of our interest. We propose the Tapered Gridded Estimator as an effective tool to observationally quantify both foregrounds and the cosmological 21-cm signal.Comment: 20 pages, 15 figures, 1 table.One typo corrected in Fig.13. Accepted for publication in MNRA

On Strongly Pettis Integrable Functions in Locally Convex Spaces

Sin resume

Pesticide, politics and a paradise lost: toxicity, slow violence and survival environmentalism in Ambikasutan Mangad’s "Swarga"

Ambikasutan Mangad’s “Enmakaje” (translated into English as “Swarga” by J. Devika) is a dystopic tale of socio-environmental crisis that represents the actual event of endosulfan disaster in the Indian state of Kerala in literary imagination. This paper examines how Mangad’s text represents the “slow violence” the endosulfan disaster unleashes, in encrypted and incremental ways, upon the environs, bodies and psyches of the victims. It looks into how the politics of denial tries to suppress the inconvenient truth about the invisible invasion of the foreign element in an area where the local people live in reciprocity with their immediate environment. The paper also dissects how Mangad’s use of the images of deformed human bodies with congenital anomalies in rendering the amorphous threats visible brings the environmental and disability concerns together and how these contravened and disabled bodies mark the uncanny nature of the disaster. Finally, it focuses on how the poor victims put up a collective protest in the form of an ecopopulist movement against the pesticide lobby and how their resistance to the socio-environmental injustice substantiates the fact that in a postcolonial country like India environmental issues are integrally connected to the issues of sustenance, shelter and survival of the “ecosystem people”.“Enmakaje” de Ambikasutan Mangad (traducido al inglés por J. Devika como “Swarga”) es una historia distópica de crisis socioambiental que representa el evento real del desastre del endosulfán en el estado indio de Kerala en la imaginación literaria. Este artículo examina cómo el texto de Mangad representa la “violencia lenta” que desata el desastre del endosulfán, de forma encriptada y progresiva, sobre el entorno, los cuerpos y la psique de las víctimas. Analiza cómo la política de la negación intenta suprimir la verdad incómoda sobre la invasión invisible del elemento extranjero en un área donde la gente local vive en reciprocidad con su entorno inmediato. El documento también analiza cómo el uso que hace Mangad de las imágenes de cuerpos humanos deformados con anomalías congénitas para hacer visibles las amenazas amorfas une las preocupaciones ambientales y de discapacidad y cómo estos cuerpos contravenidos y discapacitados marcan la naturaleza misteriosa del desastre. Finalmente, se centra en cómo las víctimas pobres organizan una protesta colectiva en forma de movimiento ecopopulista contra el lobby de los pesticidas y cómo su resistencia a la injusticia socioambiental corrobora el hecho de que, en un país poscolonial como la India, los problemas ambientales están integralmente conectados. a los temas de sustento, cobijo y sobrevivencia de la “gente del ecosistema”