4,906 research outputs found
Quantum Mechanics of a Rotating Billiard
Integrability of a square billiard is spontaneously broken as it rotates
about one of its corners. The system becomes quasi-integrable where the
invariant tori are broken with respect to a certain parameter, where E is the energy of the particle inside the billiard and
is the angular frequency of rotation of billiard. We study the system
classically and quantum mechanically in view of obtaining a correspondence in
the two descriptions. Classical phase space in Poincar\'{e} surface of section
shows transition from regular to chaotic motion as the parameter is
decreased. In the Quantum counterpart, the spectral statistics shows a
transition from Poisson to Wigner distribution as the system turns chaotic with
decrease in . The wavefunction statistics however show breakdown of
time-reversal symmetry as decreases
First-principles study of possible shallow donors in ZnAl2O4 spinel
ZnAl2O4 (gahnite) is a ceramic which is considered a possible transparent conducting oxide (TCO) due to its wide band gap and transparency for UV. Defects play an important role in controlling the conductivity of a TCO material along with the dopant, which is the main source of conductivity in an otherwise insulating oxide. A comprehensive first-principles density functional theory study for point defects in ZnAl2O4 spinel is presented using the Heyd, Scuseria, and Ernzerhof hybrid functional (HSE06) to overcome the band gap problem. We have investigated the formation energies of intrinsic defects which include the Zn, Al, and O vacancy and the antisite defects: Zn at the Al site (Zn-Al) and Al at the Zn site (Al-Zn). The antisite defect Al-Zn has the lowest formation energy and acts as a shallow donor, indicating possible n-type conductivity in ZnAl2O4 spinel by Al doping
Cells use molecular working memory to navigate inchanging chemoattractant fields
In order to migrate over large distances, cells within tissues and organisms rely on sensing local gradient cues which are irregular, conflicting, and changing over time and space. The mechanism how they generate persistent directional migration when signals are disrupted, while still remaining adaptive to signal's localization changes remain unknown. Here we find that single cells utilize a molecular mechanism akin to a working memory to satisfy these two opposing demands. We derive theoretically that this is characteristic for receptor networks maintained away from steady states. Time-resolved live-cell imaging of Epidermal growth factor receptor (EGFR) phosphorylation dynamics shows that cells transiently memorize position of encountered signals via slow-escaping remnant of the polarized signaling state, a dynamical 'ghost', driving memory-guided persistent directional migration. The metastability of this state further enables migrational adaptation when encountering new signals. We thus identify basic mechanism of real-time computations underlying cellular navigation in changing chemoattractant fields
A Grassmannian Etude in NMHV Minors
Arkani-Hamed, Cachazo, Cheung and Kaplan have proposed a Grassmannian
formulation for the S-matrix of N=4 Yang-Mills as an integral over link
variables. In parallel work, the connected prescription for computing tree
amplitudes in Witten's twistor string theory has also been written in terms of
link variables. In this paper we extend the six- and seven-point results of
arXiv:0909.0229 and arXiv:0909.0499 by providing a simple analytic proof of the
equivalence between the two formulas for all tree-level NMHV superamplitudes.
Also we note that a simple deformation of the connected prescription integrand
gives directly the ACCK Grassmannian integrand in the limit when the
deformation parameters equal zero.Comment: 17 page
Spices - An imperative melange - back to the roots
Ayurveda is one of the world’s oldest medical systems and remains one of India’s traditional health care systems. Natural products have been used for thousands of years in traditional medicine for many purposes. Ayurveda has many evidences for the utilization of spices to cure various diseases. They not only increase the flavor of food but also have several therapeutic values. The objective of this article is to provide an overview regarding the health benefits of most commonly used spices and their applications in dentistry
Punica Granatum L - A Nutraceutical functional food
Pomegranate is a widely used plant having medicinal properties. Pomegranates and their extracts may serve as natural alternatives due to their potency against a wide range of bacterial and viral pathogens. The synergistic action of the pomegranate constituents appears to be superior to that of single constituents.Pomegranate provides health benefits, that is, a nutraceutical food. It is used in dentistry as an active ingredient such as mouth rinse for plaque control, treatment of various oral lesions, storage media for avulsed teeth, wound healing. This paper describes the uses of pomegranate, its mechanism and various therapeutic and dental applications
The Grassmannian and the Twistor String: Connecting All Trees in N=4 SYM
We present a new, explicit formula for all tree-level amplitudes in N=4 super
Yang-Mills. The formula is written as a certain contour integral of the
connected prescription of Witten's twistor string, expressed in link variables.
A very simple deformation of the integrand gives directly the Grassmannian
integrand proposed by Arkani-Hamed et al. together with the explicit contour of
integration. The integral is derived by iteratively adding particles to the
Grassmannian integral, one particle at a time, and makes manifest both parity
and soft limits. The formula is shown to be related to those given by Dolan and
Goddard, and generalizes the results of earlier work for NMHV and N^2MHV to all
N^(k-2)MHV tree amplitudes in N=4 super Yang-Mills.Comment: 26 page
Effect of Inorganic Fertilizer and Crop Residue on Carbohydrate and Fat Content in Basmati Rice (Oryza sativa L.)
A field experiment was conducted during Kharif season of July 2013 & 2014at crop research farm SHIATS Allahabad to study the effect of inorganic fertilizer and wheat residue on carbohydrate and fat content in basmati rice. Treatments were arranged using (4x3) factorial R.B.D with three replications. Increasing level of NPK fertilizer significantly increases carbohydrate content in grain in 100% RDF ha-1over control. Among incorporation/ retention of wheat residue also increase the carbohydrate content with increasing level from 0 to 5 tone ha-1. It was lower in control and higher in highest level of wheat residue, which was at par with 2.5 t ha-1 wheat residues in the year of experiment 2013-2014. In the fat content maximum increased in 100% RDF (NPK) over control. Among the fat content maximum increased in incorporation of 5 t ha-1 wheat residue was found better than the rest of the treatment both the years of experiment 2013,14 respectively
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