1,051 research outputs found
Spin Glass and ferromagnetism in disordered Kondo lattice
The competition among spin glass (SG), ferromagnetism and Kondo effect has
been analysed in a Kondo lattice model where the inter-site coupling
between the localized magnetic moments is given by a generalized Mattis model
\cite{Mattis} which represents an interpolation between ferromagnetism and a
highly disordered spin glass. Functional integral techniques with of Grassmann
fields has been used to obtain the partition function. The static approximation
and the replica symmetric ansatz has also been used. The solution of the
problem is presented as a phase diagram temperature {\it versus} (the
strength of the intra-site interaction). If is small, for decreasing
temperature there is a second order transition from a paramagnetic to a spin
glass phase For lower temperatures, a first order transition appears where
solutions for the spin glass order parameter and the local magnetizations are
simultaneously non zero. For very low temperatures, the local magnetizations
becomes thermodinamically stables. For high , the Kondo state is
dominating. These results could be helpful to clarify the experimental
situation of .Comment: 4 pages, 1 figure, accept to be published in Physica
Formation of Cu and Ni Nanowires by Electrodeposition
In this work, the formation of Cu and Ni nanowires by electrodeposition inside alumina templates was analyzed. The depositswere performed from CuSO4 + H2SO4 and NiSO4 + NiCl2 + H3BO3 + H2SO4 solutions for the electrodeposition of Cu and Ni,respectively. To allow the cations deposition, sufficiently negative potentials were used. The experience time was rangedbetween 500s and 1h. After the metal electrodeposition, the sample was immersed in NaOH to dissolve the alumina membraneand to expose the generated deposit. The obtained nanostructures were characterized by SEM (scanning electron microscopy).Deposits were corresponded with nanowires having an average diameter of 300 nm. The length of the nanostructures was about10 microns.Fil: Meier, Lorena Alejandra. Universidad Nacional del Sur. Departamento de Ingeniería Química. Instituto de Ingeniería Electroquímica y Corrosión; ArgentinaFil: Alvarez, Andrea Elizabeth. Universidad Nacional del Sur. Departamento de Ingeniería Química. Instituto de Ingeniería Electroquímica y Corrosión; ArgentinaFil: Garcia, S.G.. Universidad Nacional del Sur. Departamento de Ingeniería Química. Instituto de Ingeniería Electroquímica y Corrosión; ArgentinaFil: del Barrio, Maria Cecilia. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional del Sur. Departamento de Ingeniería Química. Instituto de Ingeniería Electroquímica y Corrosión; Argentin
Effective in Vitro Photokilling by Cell-Adhesive Gold Nanorods
Upon excitation of their localized surface plasmon resonance (LSPR) band, gold nanorods (AuNRs) show a characteristic light-to-heat transduction, a useful and versatile property for a range of biomedical applications such as photothermal therapy, drug delivery, optoacoustic imaging and biosensing, among others. Nanoparticle (NP)-mediated photothermal therapy (PTT) rests on the ability of nanomaterials to convert light energy into heat and can currently be considered as a promising method for selectively destroying tumor cells by (photo)-thermoablation. One inherent limitation to NP-mediated PTT is that the nanoparticles must arrive at the site of action to exert their function and this typically involves cellular internalization. Here we report the use of the Keggin-type polyoxometalate (POM) phosphotungstic acid (PTA) as an inorganic gelling agent for the encapsulation of plasmonic gold nanorods (AuNRs) inside a biocompatible and cell-adhesive chitosan hydrogel matrix. These functional sub-micrometric containers are non-cytotoxic and present the ability to adhere to the cytoplasmic membranes of cells avoiding any need for cellular internalization, rendering them as highly efficient thermoablating agents of eukaryotic cells in vitro
Breaking the Glass Ceiling Philosophy and Reality: A Study of Gender Progress and Career Development in the Corporate World
With the evolving nature of the business world, it has become a modern necessity to have a diverse
workforce. As such, human resources professionals and managers must be prepared for the redesign of their
organizations to be more inclusive throughout their formal hierarchies. Although the overall attitudes have
become generally more feminist, the unfortunate reality is that women continue to face internal and external
barriers which act as a ceiling to their career development and advancement
Spectral properties of a generalized chGUE
We consider a generalized chiral Gaussian Unitary Ensemble (chGUE) based on a
weak confining potential. We study the spectral correlations close to the
origin in the thermodynamic limit. We show that for eigenvalues separated up to
the mean level spacing the spectral correlations coincide with those of chGUE.
Beyond this point, the spectrum is described by an oscillating number variance
centered around a constant value. We argue that the origin of such a rigid
spectrum is due to the breakdown of the translational invariance of the
spectral kernel in the bulk of the spectrum. Finally, we compare our results
with the ones obtained from a critical chGUE recently reported in the
literature. We conclude that our generalized chGUE does not belong to the same
class of universality as the above mentioned model.Comment: 12 pages, 3 figure
Selection of Wavelet Subbands Using Genetic Algorithm for Face Recognition
Abstract. In this paper, a novel representation called the subband face is proposed for face recognition. The subband face is generated from selected subbands obtained using wavelet decomposition of the original face image. It is surmised that certain subbands contain information that is more significant for discriminating faces than other subbands. The problem of subband selection is cast as a combinatorial optimization problem and genetic algorithm (GA) is used to find the optimum subband combination by maximizing Fisher ratio of the training features. The performance of the GA selected subband face is evaluated using three face databases and compared with other wavelet-based representations.
Brans-Dicke Theory and primordial black holes in Early Matter-Dominated Era
We show that primordial black holes can be formed in the matter-dominated era
with gravity described by the Brans-Dicke theory. Considering an early
matter-dominated era between inflation and reheating, we found that the
primordial black holes formed during that era evaporate at a quicker than those
of early radiation-dominated era. Thus, in comparison with latter case, less
number of primordial black holes could exist today. Again the constraints on
primordial black hole formation tend towards the larger value than their
radiation-dominated era counterparts indicating a significant enhancement in
the formation of primordial black holes during the matter-dominaed era.Comment: 9 page
Universal Behavior of Charged Particle Production in Heavy Ion Collisions
The PHOBOS experiment at RHIC has measured the multiplicity of primary
charged particles as a function of centrality and pseudorapidity in Au+Au
collisions at sqrt(s_NN) = 19.6, 130 and 200 GeV. Two kinds of universal
behavior are observed in charged particle production in heavy ion collisions.
The first is that forward particle production, over a range of energies,
follows a universal limiting curve with a non-trivial centrality dependence.
The second arises from comparisons with pp/pbar-p and e+e- data.
N_tot/(N_part/2) in nuclear collisions at high energy scales with sqrt(s) in a
similar way as N_tot in e+e- collisions and has a very weak centrality
dependence. This feature may be related to a reduction in the leading particle
effect due to the multiple collisions suffered per participant in heavy ion
collisions.Comment: 4 Pages, 5 Figures, contributed to the Proceedings of Quark Matter
2002, Nantes, France, 18-24 July 200
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