Solar sail capture trajectories at Mercury

Mercury is an ideal environment for future planetary exploration by solar sail since it has proved difficult to reach with conventional propulsion and hence remains largely unexplored. In addition, its proximity to the Sun provides a solar sail acceleration of order ten times the sail characteristic acceleration at 1 AU. Conventional capture techniques are shown to be unsuitable for solar sails and a new method is presented. It is shown that capture is bound by upper and lower limits on the orbital elements of the approach orbit and that failure to be within limits results in a catastrophic collision with the planet. These limits are presented for a range of capture inclinations and sail characteristic accelerations. It is found that sail hyperbolic excess velocity is a critical parameter during capture at Mercury, with only a narrow allowed band in order to avoid collision with the planet. The new capture methodis demonstrated for a Mercury sample return mission

Orientation, Size, and Temperature Dependent Ductile Brittle Transition in NiAl Nanowire under Tensile Loading - A Molecular Dynamics Study

In the present paper, thermo-mechanical response of B2-NiAl nanowire along the <100>, <110>, and <111> orientations has been studied using molecular dynamics simulations. Nanowire with cross-sectional dimensions of ~20x20 Å2, ~25x25 Å2, and ~30x30 Å2 and temperature range of 10 K-900 K has been considered. A Combined effect of size, orientation, and temperature on the stress-strain behavior under uniaxial tensile loading has been presented. It has been observed that <111> oriented NiAl nanowire that is energetically most stable gives highest yield stress which further reduces with <110> and <100> orientations. A remarkable ductile brittle transition (DBT) with an increase in temperature has also been reported for all the orientations considered in the present study. The DBT observed for the nanowire has also been compared with the reported DBT of bulk B2-NiAl obtained from experiments. Alternate technique has also been proposed to increase the toughness of a given material especially at lower temperature regions, i.e. below DBT.Defence Science Journal, 2014, 64(2), pp. 179-185. DOI: http://dx.doi.org/10.14429/dsj.64.431

A record production from an integrated farming system utilising sewage enriched water

The results of experiments conducted on a pond dyke (655m²) in the Wastewater Aquaculture Division of the Central Institute of Freshwater Aquaculture, Rahara, during 1992-93 for maximising production through optimum utilisation of resources are communicated. Round the year intensive cultivation of okra (Abelmoschus esculentus), amaranth (Amaranthus gangeticus and A. viridus), water-bind weed (Ipomea aquatica), Indian spinach (Basella rubra), radish (Raphanus sativum), amaranth (Amaranthus viridis), cauliflower (Brassica oleracia var. votrytis), cabbage (Brassica oleracia var. capitota) and papaya (Carica papaya) was undertaken using the treated sewage water from fish ponds for irrigation. The pond dyke yielded 5,626.5 kg vegetable which worked out to 85.9 tons per ha per year. Multiple cropping with these vegetables excluding papaya on a 460 m² dyke recorded a production of 4,926.5 kg at the rate of 107.1t per ha/yr. An improved yearly net return of about 35% over investment could be achieved through the selection of highly productive and pest resistant vegetable crops of longer duration for integration into the system. Introduction of this type of integrated farming would enhance the overall productivity and returns from farming

Utilisation of vegetable leaves for carp production

The results of two sets of experiments on mono-culture of grass carp (Ctenopharyngodon idella) and mixed culture of carps (grass carp 50 : catla 20 : rohu 15 : mrigal 15) fed exclusively with vegetable leaves are reported. The experiments were conducted with two replicates each in 0.02 ha ponds of Wastewater Aquaculture Division of the Central Institute of Freshwater Aquaculture, Rahara during 1991-93. Monoculture of grass carp stocked at 1000/ha demonstrated an average net production of 21.0 kg/ 0.02 ha/8 months (1501 kg/ha/yr). Mixed culture of carps stocked at 5000 /ha recorded an average net production of 22.5 kg/0.02 ha/8 months (1903.7 kg/ha/yr). Field studies revealed that water bind weed (Ipomoea aquatica) is the most preferred feed of grass carp amongst vegetable leaves followed by amaranths (Amaranthus gangeticus and Amaranthus viridis), cauliflower (Brassica oleracia var. votrytis) and cabbage (Brassica oleracia var. capitata) leaves. Through selection of highly productive leaf vegetables and suitable crop planning on fallow fish pond dykes, round the year feeding programme of grass carp has been explored. Recycling of sewage effluent for vegetable production and utilisation of vegetable leaves for fish production is considered an ideal way of integrated resource management for low cost production

Higgs as a pseudo-Goldstone boson, the mu problem and gauge-mediated supersymmetry breaking

We study the interplay between the spontaneous breaking of a global symmetry of the Higgs sector and gauge-mediated supersymmetry breaking, in the framework of a supersymmetric model with global SU(3) symmetry. In addition to solving the supersymmetric flavour problem and alleviating the little hierarchy problem, this scenario automatically triggers the breaking of the global symmetry and provides an elegant solution to the mu/Bmu problem of gauge mediation. We study in detail the processes of global symmetry and electroweak symmetry breaking, including the contributions of the top/stop and gauge-Higgs sectors to the one-loop effective potential of the pseudo-Goldstone Higgs boson. While the joint effect of supersymmetry and of the global symmetry allows in principle the electroweak symmetry to be broken with little fine-tuning, the simplest version of the model fails to bring the Higgs mass above the LEP bound due to a suppressed tree-level quartic coupling. To cure this problem, we consider the possibility of additional SU(3)-breaking contributions to the Higgs potential, which results in a moderate fine-tuning. The model predicts a rather low messenger scale, a small tan beta value, a light Higgs boson with Standard Model-like properties, and heavy higgsinos.Comment: 19 pages, 6 figures. New section 3.3 on the mu/Bmu problem, more detailed analytic computation in section 4.1, error in Fig. 5 corrected, significant redactional changes (including abstract, introduction and conclusion) in order to better emphasize the main results of the paper. Title changed in journal. Final version to appear in Eur. Phys. J.

Green functions for generalized point interactions in 1D: A scattering approach

Recently, general point interactions in one dimension has been used to model a large number of different phenomena in quantum mechanics. Such potentials, however, requires some sort of regularization to lead to meaningful results. The usual ways to do so rely on technicalities which may hide important physical aspects of the problem. In this work we present a new method to calculate the exact Green functions for general point interactions in 1D. Our approach differs from previous ones because it is based only on physical quantities, namely, the scattering coefficients, $R$ and $T$, to construct $G$. Renormalization or particular mathematical prescriptions are not invoked. The simple formulation of the method makes it easy to extend to more general contexts, such as for lattices of $N$ general point interactions; on a line; on a half-line; under periodic boundary conditions; and confined in a box.Comment: Revtex, 9 pages, 3 EPS figures. To be published in PR

Parámetros ecocardiográficos de cardiopatía auricular y detección de fibrilación auricular en el ictus criptogénico

Sr, Editor: Los ictus cardioembólicos representan un 20-30% del total de los ictus isquémicos. Con la introducción en 2014 del término «ESUS» o «ictus embólico de origen indeterminado» y ante el importante número de ictus criptogénicos no lacunares, la hipótesis de una fuente embólica no conocida ha llevado a una búsqueda exhaustiva. Esta incluye la monitorización cardiaca prolongada, lo que aumenta la sensibilidad para identificar arritmias proembolígenas paroxísticas. Si bien en un inicio no se conocía la capacidad de dichos paroxismos cardiacos para ocasionar eventos isquémicos, estudios paralelos sobre la fisiopatología del ictus cardioembólico han demostrado que fibrilaciones auriculares (FA) paroxísticas de 5-6 min ya aumentan el riesgo de ictus. La escasa duración de estos episodios y el hecho de que puedan ser asintomáticos y distanciados del momento del cuadro neurológico explican su inclusión durante el ingreso hospitalario en el conjunto de ictus de etiología indeterminada. La heterogeneidad de dicho grupo, junto con el limitado uso de la monitorización cardiaca prolongada, ya sea por mala tolerancia de los pacientes o por la escasez y disparidad de los dispositivos, ha incentivado la búsqueda de parámetros que se correlacionen con mayor incidencia de FA con el objetivo de aumentar la rentabilidad de la prueba. Estos parámetros incluyen aspectos electrocardiográficos, bioquímicos y ecocardiográficos, y en el análisis de muchos de ellos se ha visto su relación, no solo con la FA, sino también su asociación directa con ictus isquémicos o recurrencias..

Flavor changing single top quark production channels at e^+e^- colliders in the effective Lagrangian description

We perform a global analysis of the sensitivity of LEP2 and e^+e^- colliders with a c.m. energy in the range 500 - 2000 GeV to new flavor-changing single top quark production in the effective Lagrangian approach. The processes considered are sensitive to new flavor-changing effective vertices such as Ztc, htc, four-Fermi tcee contact terms as well as a right-handed Wtb coupling. We show that e^+ e^- colliders are most sensitive to the physics responsible for the contact tcee vertices. For example, it is found that the recent data from the 189 GeV LEP2 run can be used to rule out any new flavor physics that can generate these four-Fermi operators up to energy scales of \Lambda > 0.7 - 1.4 TeV, depending on the type of the four-Fermi interaction. We also show that a corresponding limit of \Lambda > 1.3 - 2.5 and \Lambda > 17 - 27 TeV can be reached at the future 200 GeV LEP2 run and a 1000 GeV e^+e^- collider, respectively. We note that these limits are much stronger than the typical limits which can be placed on flavor diagonal four-Fermi couplings. Similar results hold for \mu^+\mu^- colliders and for tu(bar) associated production. Finally we briefly comment on the necessity of measuring all flavor-changing effective vertices as they can be produced by different types of heavy physics.Comment: 34 pages, plain latex, 7 figures embadded in the text using epsfig. Added new references and discussions regarding their relevance to the paper. Added more comments on the comparison between flavor-changing and flavor-diagonal contact terms and on the importance of measuring the Ztc verte