Alignment and morphology of elliptical galaxies: the influence of the cluster tidal field

We investigate two possible effects of the tidal field induced by a spherical cluster on its elliptical galaxy members: the modification of the ellipticity of a spherical galaxy and the isophotal alignment in the cluster radial direction of a misaligned prolate galaxy. Numerical N-body simulations have been performed for radial and circular galactic orbits. The properties of the stars' zero--velocity surfaces in the perturbed galaxies are explored briefly, and the adiabaticity of the galaxy to the external field is discussed. For a choice of parameters characteristic of rich clusters we find that the induced ellipticity on a spherical galaxy is below or close to the detectability level. But we find that the tidal torque can result in significant isophotal alignment of the galaxies' major axis with the cluster radial direction if the galaxy is outside the cluster core radius. The time required for the alignment is very short compared with the Hubble time. A significant increase in the ellipticity of the outer isophotes of the prolate model is also found, but with no observable isophotal twisting. Our main prediction is an alignment segregation of the elliptical galaxy population according to whether their orbits lie mostly outside or inside the cluster core radius. These results also suggest that galactic alignment in rich clusters is not incompatible with a bottom-up galaxy formation scenario.Comment: 20 pages, uuencoded compressed tarred postscrip

The scaling of the decoherence factor of a qubit coupled to a spin chain driven across quantum critical points

We study the scaling of the decoherence factor of a qubit (spin-1/2) using the central spin model in which the central spin (qubit) is globally coupled to a transverse XY spin chain. The aim here is to study the non-equilibrium generation of decoherence when the spin chain is driven across (along) quantum critical points (lines) and derive the scaling of the decoherence factor in terms of the driving rate and some of the exponents associated with the quantum critical points. Our studies show that the scaling of logarithm of decoherence factor is identical to that of the defect density in the final state of the spin chain following a quench across isolated quantum critical points for both linear and non-linear variations of a parameter even if the defect density may not satisfy the standard Kibble-Zurek scaling. However, one finds an interesting deviation when the spin chain is driven along a critical line. Our analytical predictions are in complete agreement with numerical results. Our study, though limited to integrable two-level systems, points to the existence of a universality in the scaling of the decoherence factor which is not necessarily identical to the scaling of the defect density.Comment: 5 pages, 2 figures, Final and accepted versio

The poetic is political….and other notes on engaged scholarship

Instrumental and objectivist logics maintain a hegemonic place in Western scholarship, reasoning skills powerfully equipped to address certain dilemmas even as they may obscure other ways of knowing. In this chapter, we enlarge dominant notions of rationality by offering an aesthetic view of knowledge as vital for engaged communication scholarship. Our interest in aesthetic logics parallels concerns that have led scholars to develop feminist practices of inquiry (e.g., Harding, 1998; Hesse-Biber, 2007), interrogate the aesthetics of representations in West-centric knowledge structures from postcolonial and Subaltern Studies standpoints (e.g., Broadfoot & Munshi, 2007; Dutta, 2007, 2008), focus on autoethnographic and poetic accounts ( e.g., Carr, 2003; Ellingson, 2009), introduce reflexivity and the politics of personhood in the scholarly process ( e.g., Harding, 1991; Reinharz, 1992), and adopt narrative and dialogic understandings of knowledge constructions (e.g., Frank, 2005; Harter, 2005). Loosely coupled, these research trajectories advance alternative rationalities for witnessing and answering salient social issues. We argue for the theoretical and practical incorporation of aesthetic rationalities in engaged scholarship-logics of poss ibility that cultivate individuals \u27 capacities to imagine otherwise. Reimagining scholarly inquiry to reflect and embrace aesthetic logics requires us to rethink our methods of data collection, analysis, and representation and our own roles as researchers and writers . When we resist the art/science dichotomy, opportunities abound for sensemaking and representation that embody aesthetic ways of knowing. Furthermore, rejection of dichotomous thinking opens up possibilities for listening to ways of knowing that lie beyond the realm of Eurocentric knowledge structures (Dutta, in press). Even after the interpretive turn, instrumental and objectivist logics often underlie and sometimes constrain the processes and products of social scientific research (Denzin & Lincoln, 2005). Traditional structures and modes of research offer important but limited conceptualizations of knowing. We can open ourselves to other ways of asking questions that include overt attention to aesthetic sensibilities . We need not reject or abandon traditional modes of research. Instead, we can enlarge the realm of possibilities for what counts as accepted research practices and advance methods for studying the aesthetic nature of communal life (Ellingson, 2009). In this chapter, we develop an understanding of rationality that incorporates imagination, and we explore methodologies that draw on creative sensibilities. We then articul ate the salience of creativity for rendering credible previously subjugated voices, and we articulate its value for engaged communication theory and research

No ν\nu floors: Effective field theory treatment of the neutrino background in direct dark matter detection experiments

Distinguishing a dark matter interaction from an astrophysical neutrino-induced interaction will be major challenge for future direct dark matter searches. In this paper, we consider this issue within non-relativistic Effective Field Theory (EFT), which provides a well-motivated theoretical framework for determining nuclear responses to dark matter scattering events. We analyze the nuclear energy recoil spectra from the different dark matter-nucleon EFT operators, and compare to the nuclear recoil energy spectra that is predicted to be induced by astrophysical neutrino sources. We determine that for 11 of the 14 possible operators, the dark matter-induced recoil spectra can be cleanly distinguished from the corresponding neutrino-induced recoil spectra with moderate size detector technologies that are now being pursued, e.g., these operators would require 0.5 tonne years to be distinguished from the neutrino background for low mass dark matter. Our results imply that in most models detectors with good energy resolution will be able to distinguish a dark matter signal from a neutrino signal, without the need for much larger detectors that must rely on additional information from timing or direction

Remarks on the Noncommutative Gravitational Quantum Well

A planar phase space having both position and momentum noncommutativity is defined in a more inclusive setting than that considered elsewhere. The dynamics of a particle in a gravitational quantum well in this space is studied. The use of the WKB approximation and the virial theorem enable analytic discussions on the effect of noncommutativity. Consistent results are obtained following either commutative space or noncommutative space descriptions. Comparison with recent experimental data with cold neutrons at Grenoble imposes an upper bound on the noncommutative parameter. Also, our results are compared with a recent numerical analysis of a similar problem.Comment: Latex, 17 pages, Title changed, minor modifications, 3 new references added, To appear in Phys. Rev.

Performance of broccoli (Brassica oleracea var. italica) under drip irrigation and mulch

Field experiment was conducted at Central Research Farm of Bidhan Chandra Krishi Viswavidyala, Gayespur, West Bengal during winter seasons of 2011-12 and 2012-13 to assess the comparative effectiveness of drip and conventional surface irrigation with and without mulch on growth and yield of broccoli. The experiment was laid out in split-plot design replicated thrice. Main plot treatments consist of four levels of irrigation such as surface irrigation with IW/CPE 1.0 and three drip irrigation at 1.0, 0.8 and 0.6 ETc (crop-evapotranspiration), and three mulch levels like no mulch, black polythene mulch and paddy straw mulch @ 5t/ha in sub-plots. The results showed that drip irrigation at 0.8 ETc showed significantly higher (P = 0.05) plant height (45.69 cm), no of leaves plant-1 (17.66), leaf size index (743.99 cm2), plant spread (89.94 cm), curd diameter (14.43 cm) and marketable curd yield (17.82 t ha-1) of broccoli, which was at par with drip at 1.0 ETc. Minimum growth and yield was obtained with drip irrigation at 0.6 ETc in both the years. Similarly, significantly the highest (P = 0.05) plant variables and curd yield was obtained with use of black polythene mulch over paddy straw and no mulch treatments. However, drip irrigation at 0.6 ETc registered maximum water use efficiency of 117.31kg ha-mm-1 and water saving of 38.43%. The interaction effect showed that drip irrigation at 0.8 ETc along with black polythene mulch produced significantly higher marketable curd yield. The experimental findings can be recommended for growing high value crop broccoli with water saving drip irrigation at ETc 0.8 along with plastic mulch technology in the water scarce regions of West Bengal

Adiabatic multicritical quantum quenches: Continuously varying exponents depending on the direction of quenching

We study adiabatic quantum quenches across a quantum multicritical point (MCP) using a quenching scheme that enables the system to hit the MCP along different paths. We show that the power-law scaling of the defect density with the rate of driving depends non-trivially on the path, i.e., the exponent varies continuously with the parameter $\alpha$ that defines the path, up to a critical value $\alpha= \alpha_c$; on the other hand for $\alpha \geq \alpha_c$, the scaling exponent saturates to a constant value. We show that dynamically generated and {\it path($\alpha$)-dependent} effective critical exponents associated with the quasicritical points lying close to the MCP (on the ferromagnetic side), where the energy-gap is minimum, lead to this continuously varying exponent. The scaling relations are established using the integrable transverse XY spin chain and generalized to a MCP associated with a $d$-dimensional quantum many-body systems (not reducible to two-level systems) using adiabatic perturbation theory. We also calculate the effective {\it path-dependent} dimensional shift $d_0(\alpha)$ (or the shift in center of the impulse region) that appears in the scaling relation for special paths lying entirely in the paramagnetic phase. Numerically obtained results are in good agreement with analytical predictions.Comment: 5 pages, 4 figure