6,552 research outputs found
Characterizing correlations with full counting statistics: classical Ising and quantum XY spin chains
We propose to describe correlations in classical and quantum systems in terms
of full counting statistics of a suitably chosen discrete observable. The
method is illustrated with two exactly solvable examples: the classical
one-dimensional Ising model and the quantum spin-1/2 XY chain. For the
one-dimensional Ising model, our method results in a phase diagram with two
phases distinguishable by the long-distance behavior of the Jordan-Wigner
strings. For the quantum XY chain, the method reproduces the previously known
phase diagram.Comment: 6 pages, section on Lee-Yang zeros added, published versio
Rare decay pi0 -> e+e-: theory confronts KTeV data
Within the dispersive approach to the amplitude of the rare decay pi0 -> e+e-
the nontrivial dynamics is contained only in the subtraction constant. We
express this constant, in the leading order in (m_e/\Lambda)^2 perturbative
series, in terms of the inverse moment of the pion transition form factor given
in symmetric kinematics. By using the CELLO and CLEO data on the pion
transition form factor given in asymmetric kinematics the lower bound on the
decay branching ratio is found. The restrictions following from QCD allow us to
make a quantitative prediction for the branching B(pi0 -> e+e-) =(6.2\pm
0.1)*10^{-8} which is 3\sigma below the recent KTeV measurement. We confirm our
prediction by using the quark models and phenomenological approaches based on
the vector meson dominance. The decays \eta -> l^+l^- are also discussed.Comment: 7 pages, 1 figur
Synthesis of inorganic dyes based on plasmonic silver nanoparticles for the visible and infrared regions of the spectrum
The effect of various technological factors during the multistage synthesis of plasmonic silver particles in aqueous solutions on nanoparticle size, morphology, and color is studied. The synthesized suspensions are found to contain tabular silver nanoparticles of hexagonal and triangular shape. The foundations of the technology for synthesizing stable silver colloids with a high silver concentration for the visible and nearinfrared regions of the spectrum are developed
Effects caused by glutamic acid and hydrogen peroxide on the morphology of hydroxyapatite, calcium hydrogen phosphate, and calcium pyrophosphate
Reacting hydroxyapatite with H2O2 vapor at 10°C and brushite CaHPO4 · 2H2O with 90% H2O2 solution at 0°C (the hydroxyapatite and brushite were both prepared in the presence of glutamic acid) yielded the relevant peroxo solvates containing up to 18% hydrogen peroxide. The peroxo compounds and their degradation products obtained at 170–960°C were morphologically studied (using SEM). The factors influencing particle sizes are considered
An X-ray photoelectron spectroscopy study of uranyl-chitosan interaction
An X-ray photoelectron spectroscopy study of uranium sorption by spherically-granulated chitosan in sulphate solutions, as well as the study of the nature of the U(VI) - chitosan interaction was carried out in this work. The X-ray photoelectron spectroscopy analysis showed that the uranyl - chitosan interaction results in the formation of complexes with aminogroup nitrogen, and possibly chitin ring oxygens and free hydroxyl groups in the equatorial plane. Under the UHV in the spectrometer chamber, the uranyl-amin and uranyl-hyroxide bonds were shown to break and tetravalent uranium compounds were shown to form on the sample surface. Hydroxyl groups were shown to evaporate. The calculated DG0 = -1,3 kJ/mol can be an evidence of several concurrent processes, some of which require energy, as well as of the formation of a surface chemical compound
Methyltrimethoxysilane-based elastic aerogels: effects of the supercritical medium on structure-sensitive properties
Effects caused by the type of solvent used for supercritical drying on the properties of methyltrimethoxysilane-based aerogels were studied. All of the aerogel samples studied were found to be hydrophobic and to efficiently adsorb nonpolar organic compounds
New Goldstone multiplet for partially broken supersymmetry
The partial spontaneous breaking of rigid N=2 supersymmetry implies the
existence of a massless N=1 Goldstone multiplet. In this paper we show that the
spin-(1/2,1) Maxwell multiplet can play this role. We construct its full
nonlinear transformation law and find the invariant Goldstone action. The
spin-1 piece of the action turns out to be of Born-Infeld type, and the full
superfield action is duality invariant. This leads us to conclude that the
Goldstone multiplet can be associated with a D-brane solution of superstring
theory for p=3. In addition, we find that N=1 chirality is preserved in the
presence of the Goldstone-Maxwell multiplet. This allows us to couple it to N=1
chiral and gauge field multiplets. We find that arbitrary Kahler and
superpotentials are consistent with partially broken N=2 supersymmetry.Comment: Latex, 13 pages. Version to appear in Phys. Rev.
Macroporous Composite Cryogels with Embedded Polystyrene Divinylbenzene Microparticles for the Adsorption of Toxic Metabolites from Blood
Composite monolithic adsorbents were prepared by the incorporation of neutral polystyrene divinylbenzene (PS-DVB) microparticles into macroporous polymer structures produced by cryogelation of agarose or poly(vinyl alcohol). The composite
materials exhibited excellent flow-through properties. Scanning electron microscopy of the composite cryogels revealed that the microparticles were covered by thin films of poly(vinyl alcohol) or agarose and thus were withheld in the monolith structure. Plain PS-DVB microparticles showed efficient adsorption of albumin-bound toxins related to liver failure (bilirubin and cholic acid) and of cytokines (tumor necrosis factor-alpha and interleukin-6). The rates of adsorption and the amount of adsorbed factors were lower for the embedded microparticles as compared to the parent PS-DVB microparticles, indicating the importance of the accessibility of the adsorbent pores. Still, the macroporous composite materials showed efficient adsorption of albuminbound
toxins related to liver failure as well as efficient binding of cytokines, combined with good blood compatibility. Thus, the incorporation of microparticles into macroporous polymer structures may provide an option for the development of adsorption modules for extracorporeal blood purification
Mathematical retroreflectors
Retroreflectors are optical devices that reverse the direction of incident
beams of light. Here we present a collection of billiard type retroreflectors
consisting of four objects; three of them are asymptotically perfect
retroreflectors, and the fourth one is a retroreflector which is very close to
perfect. Three objects of the collection have recently been discovered and
published or submitted for publication. The fourth object - notched angle - is
a new one; a proof of its retroreflectivity is given.Comment: 32 pages, 19 figure
Relativity tests by complementary rotating Michelson-Morley experiments
We report Relativity tests based on data from two simultaneous
Michelson-Morley experiments, spanning a period of more than one year. Both
were actively rotated on turntables. One (in Berlin, Germany) uses optical
Fabry-Perot resonators made of fused silica; the other (in Perth, Australia)
uses microwave whispering-gallery sapphire resonators. Within the standard
model extension, we obtain simultaneous limits on Lorentz violation for
electrons (5 coefficients) and photons (8) at levels down to ,
improved by factors between 3 and 50 compared to previous work.Comment: 5 pages revtex, 2 figure
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