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Search Results: 1 - 10 of 208459 matches for " L. Banin "
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One-loop effective action for ${\cal N}=4$ SYM theory in the hypermultiplet sector - leading low-energy approximation and beyond
A. T. Banin,I. L. Buchbinder,N. G. Pletnev
Physics , 2003, DOI: 10.1103/PhysRevD.68.065024
Abstract: We develop the derivative expansion of the one-loop ${\cal N}=4$ SYM effective action depending both on ${\cal N}=2$ vector multiplet and on hypermultiplet background fields. We get a new derivation of the complete ${\cal N}=4$ supersymmetric low-energy effective action obtained in hep-th/0111062 and find subleading corrections to it. A problem of ${\cal N}=4$ supersymmetry of the results is discussed. Using the formalism of ${\cal N}=2$ harmonic superspace and exploring on-shell hidden ${\cal N}=2$ supersymmetry of ${\cal N}=4$ SYM theory we construct the appropriate hypermultiplet-depending contributions. The hidden ${\cal N}=2$ supersymmetry requirements allow to get a leading, in hypermultiplet derivatives, part of the correct ${\cal N}=4$ supersymmetric functional containing $F^{8}$ among the component fields.
Low-Energy Effective Action of N=2 Gauge Multiplet Induced by Hypermultiplet Matter
A. T. Banin,I. L. Buchbinder,N. G. Pletnev
Physics , 2000, DOI: 10.1016/S0550-3213(00)00735-5
Abstract: We study one-loop effective action of hypermultiplet theory coupled to external N=2 vector multiplet. We formulate this theory in N=1 superspace and develop a general approach to constructing derivative expansion of the effective action based on an operator symbol technique adopted to N=1 supersymmetric field models. The approach under consideration allows to investigate on a unique ground a general structure of effective action and obtain both N=2 superconformal invariant (non-holomorphic) corrections and anomaly (holomorphic) corrections. The leading low-energy contributions to effective action are found in explicit form.
On Low-Energy Effective Action in N=2 Super Yang-Mills Theories on Non-Abelian Background
A. T. Banin,I. L. Buchbinder,N. G. Pletnev
Physics , 2002, DOI: 10.1103/PhysRevD.66.045021
Abstract: We compute the non-holomorphic corrections to low-energy effective action (higher derivative terms) in N=2, SU(2) SYM theory coupled to hypermultiplets on a non-abelian background for a class of gauge fixing conditions. A general procedure for calculating the gauge parameters depending contributions to one-loop superfield effective action is developed. The one-loop non-holomorphic effective potential is exactly found in terms of Euler dilogarithm function for specific choice of gauge parameters.
Height-diameter allometry of tropical forest trees
T. R. Feldpausch,L. Banin,O. L. Phillips,T. R. Baker
Biogeosciences Discussions , 2010, DOI: 10.5194/bgd-7-7727-2010
Abstract: Tropical tree height-diameter (H:D) relationships may vary by forest type and region making large-scale estimates of above-ground biomass subject to bias if they ignore these differences in stem allometry. We have therefore developed a new global tropical forest database consisting of 39 955 concurrent H and D measurements encompassing 283 sites in 22 tropical countries. Utilising this database, our objectives were: 1. to determine if H:D relationships differ by geographic region and forest type (wet to dry forests, including zones of tension where forest and savanna overlap). 2. to ascertain if the H:D relationship is modulated by climate and/or forest structural characteristics (e.g. stand-level basal area, A). 3. to develop H:D allometric equations and evaluate biases to reduce error in future local-to-global estimates of tropical forest biomass. Annual precipitation coefficient of variation (PV), dry season length (SD), and mean annual air temperature (TA) emerged as key drivers of variation in H:D relationships at the pantropical and region scales. Vegetation structure also played a role with trees in forests of a high A being, on average, taller at any given D. After the effects of environment and forest structure are taken into account, two main regional groups can be identified. Forests in Asia, Africa and the Guyana Shield all have, on average, similar H:D relationships, but with trees in the forests of much of the Amazon Basin and tropical Australia typically being shorter at any given D than their counterparts elsewhere. The region-environment-structure model with the lowest Akaike's information criterion and lowest deviation estimated stand-level H across all plots to within a median –2.7 to 0.9% of the true value. Some of the plot-to-plot variability in H:D relationships not accounted for by this model could be attributed to variations in soil physical conditions. Other things being equal, trees tend to be more slender in the absence of soil physical constraints, especially at smaller D. Pantropical and continental-level models provided only poor estimates of H, especially when the roles of climate and stand structure in modulating H:D allometry were not simultaneously taken into account.
The Discrete Logarithm Problem in Bergman's non-representable ring
Matan Banin,Boaz Tsaban
Mathematics , 2012,
Abstract: Bergman's Ring $E_p$, parameterized by a prime number $p$, is a ring with $p^5$ elements that cannot be embedded in a ring of matrices over any commutative ring. This ring was discovered in 1974. In 2011, Climent, Navarro and Tortosa described an efficient implementation of $E_p$ using simple modular arithmetic, and suggested that this ring may be a useful source for intractable cryptographic problems. We present a deterministic polynomial time reduction of the Discrete Logarithm Problem in $E_p$ to the classical Discrete Logarithm Problem in $\Zp$, the $p$-element field. In particular, the Discrete Logarithm Problem in $E_p$ can be solved, by conventional computers, in sub-exponential time.
A reduction of semigroup DLP to classic DLP
Matan Banin,Boaz Tsaban
Computer Science , 2013,
Abstract: We present a polynomial-time reduction of the discrete logarithm problem in any periodic (a.k.a. torsion) semigroup (SGDLP) to the same problem in a subgroup of the same semigroup. It follows that SGDLP can be solved in polynomial time by quantum computers, and that SGDLP has subexponential algorithms whenever the classic DLP in the corresponding groups has subexponential algorithms.
Coset realizations of (super)twistor spaces and structure of (super)twistor correspondence
A. T. Banin,N. G. Pletnev
Physics , 1995,
Abstract: New types "extended" (super)conformal algebras $G^{(\frac n2)}$ are presented. (Su\-per)twistor spaces $T$ are subspaces in cosets $G^{(\frac n2)}/H$. The (super)twistor correspondence has a cleary defined geometrical meaning.
Covariant technique of derivative expansion of one-loop effective action
N. G. Pletnev,A. T. Banin
Physics , 1998, DOI: 10.1103/PhysRevD.60.105017
Abstract: A simple systematic method for calculating derivative expansions of the one-loop effective action is presented. This method is based on using symbols of operators and well known deformation quantization theory. To demonstrate its advantages we present several examples of application for scalar theory, Yang-Mills theory, and scalar electrodynamics. The superspace formulation of the method is considered for K\"ahlerian and non-K\"ahlerian quantum corrections for Wess-Zumino and for Heisenberg-Euler lagrangians in super QED models.
Application of symbol-operator technique for effective action computation
A. T. Banin,N. G. Pletnev
Physics , 2001, DOI: 10.1142/S0217751X02010194
Abstract: In the present talk we briefly demonstrate an elegant and effective technique for calculation of the trace expansion in the derivatives of background fields. One of main advantages of the technique is manifestly (super)symmetrical and gauge invariant form of expressions on all stages of calculations. Other advantage is the universality of the calculation method. Some particular examples and results are presented.
Antibacterial and antibiofilm properties of yttrium fluoride nanoparticles
Lellouche J, Friedman A, Gedanken A, Banin E
International Journal of Nanomedicine , 2012, DOI: http://dx.doi.org/10.2147/IJN.S37075
Abstract: ntibacterial and antibiofilm properties of yttrium fluoride nanoparticles Original Research (1700) Total Article Views Authors: Lellouche J, Friedman A, Gedanken A, Banin E Published Date November 2012 Volume 2012:7 Pages 5611 - 5624 DOI: http://dx.doi.org/10.2147/IJN.S37075 Received: 16 August 2012 Accepted: 12 September 2012 Published: 08 November 2012 Jonathan Lellouche,1,2 Alexandra Friedman,2 Aharon Gedanken,2 Ehud Banin1 1Biofilm Research Laboratory, The Mina and Everard Goodman Faculty of Life Sciences, 2Kanbar Laboratory for Nanomaterials, Department of Chemistry, Institute for Nanotechnology and Advanced Materials, Bar-Ilan University, Ramat-Gan, Israel Abstract: Antibiotic resistance has prompted the search for new agents that can inhibit bacterial growth. Moreover, colonization of abiotic surfaces by microorganisms and the formation of biofilms is a major cause of infections associated with medical implants, resulting in prolonged hospitalization periods and patient mortality. In this study we describe a water-based synthesis of yttrium fluoride (YF3) nanoparticles (NPs) using sonochemistry. The sonochemical irradiation of an aqueous solution of yttrium (III) acetate tetrahydrate [Y(Ac)3 (H2O)4], containing acidic HF as the fluorine ion source, yielded nanocrystalline needle-shaped YF3 particles. The obtained NPs were characterized by scanning electron microscopy and X-ray elemental analysis. NP crystallinity was confirmed by electron and powder X-ray diffractions. YF3 NPs showed antibacterial properties against two common bacterial pathogens (Escherichia coli and Staphylococcus aureus) at a μg/mL range. We were also able to demonstrate that antimicrobial activity was dependent on NP size. In addition, catheters were surface modified with YF3 NPs using a one-step synthesis and coating process. The coating procedure yielded a homogeneous YF3 NP layer on the catheter, as analyzed by scanning electron microscopy and energy dispersive spectroscopy. These YF3 NP-modified catheters were investigated for their ability to restrict bacterial biofilm formation. The YF3 NP-coated catheters were able to significantly reduce bacterial colonization compared to the uncoated surface. Taken together, our results highlight the potential to further develop the concept of utilizing these metal fluoride NPs as novel antimicrobial and antibiofilm agents, taking advantage of their low solubility and providing extended protection.
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