bluuebunny/crossref_metadata_2025 huggingface dataset:
Reconciling solvent effects on rotamer populations in carbohydrates  A joint MD and NMR analysis
Authors: Gonzalez-Outeiriño Jorge , Kirschner Karl N , Thobhani Smita , Woods Robert J
Published: May 2006

The rotational preferences of the hydroxymethyl group in pyranosides is known to depend on the local environment, whether in solid, solution, or gas phase. By combining molecular dynamics (MD) simulations with NMR spectroscopy the rotational preferences for the ω angle in methyl 2,3-di-O-methyl-α-D-glucopyranoside (3) and methyl 2,3-di-O-methyl-α-D-galactopyranoside (6) in a variety of solvents, with polarities ranging from 80 to 2.3 D have been determined. The effects of solvent polarity on intramolecular hydrogen bonding have been identified and quantified. In water, the internal hydrogen bonding networks are disrupted by competition with hydrogen bonds to the solvent. When the internal hydrogen bonds are differentially disrupted, the rotamer populations associated with the ω angle may be altered. In the case of 3 in water, the preferential disruption of the interaction between HO6 and O4 destabilizes the tg rotamer, leading to the observed preference for gauche rotamers. Without the hydrogen bond enhancement offered by a low polarity environment, both 3 and 6 display rotamer populations that are consistent with expectations based on the minimization of repulsive intramolecular oxygenoxygen interactions. In a low polarity environment, HO6 prefers to interact with O4, however, in water these interactions are markedly weakened, indicating that HO6 acts as a hydrogen bond donor to water.Key words: carbohydrate, rotamer, molecular dynamics simulation, MD, NMR.
Pyrrolotriazine-5-carboxylate ester inhibitors of EGFR and HER2 protein tyrosine kinases and a novel one-pot synthesis of C-4 subsitituted pyrrole-2,3-dicarboxylate diesters
Authors: Mastalerz Harold , Gavai Ashvinikumar V , Fink Brian , Struzynski Charles , Tarrant James , Vite Gregory D , Wong Tai W , Zhang Guifen , Vyas Dolatrai M
Published: May 2006

Pyrrolotriazines with an ester group at C-5 were prepared and evaluated as inhibitors of the EGFR and HER2 receptor tyrosine kinases, validated targets for cancer therapy. The C-5 ester (15) was at least as potent as its C-6 ester analogue (17), an example of a known series of pyrrolotriazine EGRF/HER2 kinase inhibitors that show good biochemical and cellular activity. The C-5 esters were synthesized from pyrrole 2,3-diesters that were made by a new, one-pot procedure. This involved reaction of readily available N-tosyl derivatives of α-amino acid esters or ketones with triphenylphosphine and diethyl acetylenedicarboxylate to form 3-pyrrolines via an intramolecular Wittig olefination. The 3-pyrroline intermediates were not isolated but treated directly with base to eliminate toluenesulfinic acid and generate the pyrrole 2,3-diesters in good yield.Key words: pyrrolotriazine, EGFR, HER2, pyrrole, intramolecular Wittig reaction.
Cyclodextrin derivatives with cyanohydrin and carboxylate groups as artificial glycosidases
Authors: Ortega-Caballero Fernando , Bols Mikael
Published: May 2006

Two cyclodextrin derivatives (1 and 2) were prepared in an attempt to create glycosidase mimics with a general acid catalyst and a nucleophilic carboxylate group. The catalysts 1 and 2 were found to catalyse the hydrolysis of 4-nitrophenyl β-D-glucopyranoside at pH 8.0, but rapidly underwent decomposition with loss of hydrogen cyanide to convert the cyanohydrin to the corresponding aldehyde. The initial rate of the catalysis shows that the cyanohydrin group in these molecules functions as a good catalyst, but that the carboxylate has no positive effect. The decomposition product aldehydes display little or no catalysis. A mechanism for the decomposition is suggested.Key words: biomimicry, enzyme model, kinetics, intramolecular reaction.
Synthesis and biological evaluation of 5-(alkyn-1-yl)-1-(p-toluenesulfonyl)uracil derivatives
Authors: Janeba Zlatko , Balzarini Jan , Andrei Graciela , Snoeck Robert , Clercq Erik De , Robins Morris J
Published: May 2006

Sonogashira coupling of 5-iodouracil (2) and trimethylsilylacetylene gave 5-(trimethylsilylethynyl)uracil (3), which was deprotected to give 5-ethynyluracil (4). Copper(I)-catalyzed cyclization of 4 gave furo[2,3-d]pyrimidin-2(3H)-one (5). Tosylation of 2 and 4 gave the 1-(p-toluenesulfonyl) derivatives 6 and 7, respectively. The tosylated compound 6 and trimethylsilylacetylene did not undergo Sonogashira coupling, and copper(I)-catalyzed cyclization of 7 did not occur. Coupling of 2 with several terminal alkynes gave 5-(alkyn-1-yl)uracil derivatives (9), which underwent tosylation to produce the targeted 5-(alkyn-1-yl)-1-(p-toluenesulfonyl)uracil compounds (11). Copper(I)-catalyzed cyclization of 9 gave the respective furopyrimidines (10) in low yields. Again, cyclization did not occur with the tosyl derivatives (11). Activity against varicella-zoster virus (VZV) was observed with longer-chain analogues of 9 and 11, and compound 7 showed activity against human cytomegalovirus (HCMV) at near cytotoxic levels.Key words: antiviral screening, furo[2,3-d]pyrimidin-2(3H)-one derivatives, Sonogashira coupling, 1-(p-toluenesulfonyl)pyrimidine derivatives.
Sulfonated-polydimethylsiloxane (PDMS) microdevices with enhanced electroosmotic pumping and stability
Authors: Wang Bin , Horton J Hugh , Oleschuk Richard D
Published: May 2006

Polydimethylsiloxane (PDMS) microfluidic devices offer several advantages in terms of cost and ease of fabrication compared with those fabricated from both glass and silicon materials. PDMS, however, has some potential disadvantages compared with other materials including high hydrophobicity, which makes filling the micron-sized channels difficult, and minimal surface charge resulting in reduced electroosmotic flow (EOF). Here, we describe the oxidation of the PDMS surface to form silanol groups using both air plasma and a discharge from a Tesla coil, and subsequent modification to form sulfonated-PDMS surfaces. The flow performance of freshly prepared and aged sulfonated-PDMS chips was determined at pH 5 and compared with those of unmodified and oxidized PDMS chips. The electroosmotic mobility (µeo) for a sulfonated-PDMS microdevice was determined at various pH values (pH 3~8) and compared with that for an oxidized PDMS chip. The lower pKa of a sulfonic acid modified surface compared with a silanol modified surface generated a stronger EOF over the entire pH range studied. Chemical force titrations were used to characterize the changes in functional groups present on the surface of freshly prepared and aged sulfonated-PDMS surfaces. These experiments show that the sulfonated-PDMS is a superior material for use in microfluidic applications because (i) it supports EOF over a much wider range of pH than similar polymer materials and (ii) is less susceptible to degradation of its EOF rate owing to air aging effects and surface reorganization.Key words: polydimethylsiloxane (PDMS), sulfonated surface modification, electroosmotic flow (EOF), aging effect, chemical force titrations.
Convenient preparation of aryl-substituted nortropanes by SuzukiMiyaura methodology
Authors: Ghosh Shyamali , Kinney William A , Gauthier Diane A , Lawson Edward C , Hudlicky Tomas , Maryanoff Bruce E
Published: May 2006

The synthesis of a new bicyclic vinyl boronate (5) was accomplished from N-Boc-nortropinone (6) in two steps. The SuzukiMiyaura coupling of 5 to a variety of aryl bromides and triflates afforded 3-aryl-8-azabicyclo[3.2.1]oct-2-enes in good yields by adjusting the substrate and (or) reaction conditions. Reduction to the 3-aryl-8-azabicyclo[3.2.1]octanes was achieved by hydrogenation. Interestingly, the coupling was also successful with benzyl bromides, providing entry into another group of intermediates.Key words: nortropane, SuzukiMiyaura, boronate, piperidine, GPCR, benzyl bromide.
Lanthanum-catalyzed aqueous acylation of monosaccharides by benzoyl methyl phosphate
Authors: Gray Ian James , Ren Rui , Westermann Bernhard , Kluger Ronald
Published: May 2006

It was previously reported that diols dissolved in water (pH 8, EPPS buffer) react with benzoyl methyl phosphate (BMP) in the presence of lanthanide ions to form monobenzoyl esters. We have investigated the possibility of extending this process to include formation of esters of monosaccharides in water from lanthanide-catalyzed reactions with BMP. The combination of methyl-α-D-glucopyranoside and BMP in the presence of lanthanum trichloride gave selective monoacylation of the 2- and 6-hydroxyl groups in a ratio of 2:1. The likely mechanism involves preferential bisbidentate coordination of BMP and the diol to lanthanide ion (which explains how an ester forms when water is in enormous excess) followed by base-catalyzed intramolecular acyl transfer. The method should be generally applicable where a selective acylation reaction in water as solvent is desirable. Key words: benzoyl methyl phosphate, lanthanide, catalysis, water, monoacylation, selective.
Chemical and chemoenzymatic synthesis of a trisaccharide fragment of Tsukamurella paurometabola lipoarabinomannan
Authors: Ridgway Karen M , Shi Wei , Lin Shuang-Jun , Palcic Monica M , Lowary Todd L
Published: May 2006

The synthesis of a trisaccharide fragment (1) of the lipoarabinomannan from Tsukamurella paurometabola is reported. Two approaches were investigated for the synthesis of the target. One was purely chemical, while the other involved the addition of one of the monosaccharide residues via a mannosyltransferase-catalyzed reaction. Both approaches produced the target in good overall yields. Thus, this chemoenzymatic approach appears to be a useful addition to the arsenal of methods for the synthesis of lipoarabinomannan-derived oligosaccharides.Key words: lipoarabinomannan, oligosaccharide, mannosyltransferase, enzymatic synthesis.
Iodosulfonation of alkenes with benzenesulfinic acid  N-iodosuccinimide  Facile preparation of α,β-unsaturated sulfones
Authors: Wolff Russell R , Basava Vikram , Giuliano Robert M , Boyko Walter J , Schauble J Herman
Published: May 2006

Reaction of alkenes and alkenols with N-iodosuccinimide (NIS) and benzenesulfinic acid in dichloromethane at room temperature affords vic-iodophenylsulfonyl adducts in good to high yields. Treatment of the iodosulfones with neutral alumina in dichloromethane at room temperature results in dehydroiodination to give the corresponding vinyl sulfones in high yield and purity by this convenient two-step procedure. Application of the iodosulfonationdehydroiodination sequence to allylic alcohols and silyl ethers gave γ-oxygenated, α,β-unsaturated phenylsulfones, while the attempted iodosulfonation of glycals, as intermediates to vinyl sulfones, resulted in addition of benzenesulfinic acid with double bond shift (Ferrier rearrangement). Key words: iodosulfonation, vinyl sulfones, benzenesulfinic acid, N-iodosuccinimide, dehydroiodination.
Ab initio charge density analysis of (B6C)2 and B4C3 species  How to describe the bonding pattern?
Authors: Foroutan-Nejad Cina , Shafiee Gholam Hossein , Sadjadi Abdolreza , Shahbazian Shant
Published: May 2006

In this study, a detailed topological charge density analysis based on the quantum theory of atoms in molecules (QTAIM) developed by Bader and co-workers, has been accomplished (using the B3LYP method) on the CB62 anion and three planar isomers of the C3B4 species, which had been first proposed by Exner and Schleyer as examples of molecules containing hexacoordinate carbon atoms. The analysis uncovers the strong (covalent) interactions of boron atoms as well as the "nondirectional" interaction of central carbon atom with those peripheral atoms. On the other hand, instabilities have been found in the topological networks of (B6C)2 and B4C3(para) species. A detailed investigation of these instabilities demonstrates that the topology of charge density has a floppy nature near the equilibrium geometries of the species under study. Thus, these species seems to be best described as complexes of a relatively concrete ring containing boron or carbon atoms and a central carbon atom that is confined in the plane of the molecule, but with nondirectional interactions with the surrounding atoms.Key words: hypervalency, hexacoordinate carbon, quantum theory of atoms in molecules, charge density analysis, ab initio methods.
Microwave-assisted regioselective synthesis of acyclic nucleosides through an alkylating reaction with 2-oxa-1,4-butanediol diacetate
Authors: Qu Guirong , Han Suhui , Zhang Zhiguang , Geng Mingwei , Xue Feng
Published: May 2006

An efficient and green procedure for the synthesis of purine acyclic nucleosides through microwave-assisted alkylation of various purine nucleobases with 2-oxa-1,4-butanediol diacetate in the absence of solvent and catalyst is described. The advantages of using this method include its environmental friendliness, simple manipulation, short reaction time, high regioselectivity, and good yields.Key words: acyclic nucleosides, microwave irradiation, regioselectivity, alkylation, 2-oxa-1,4-butanediol diacetate.
Indium(I) iodide promoted cleavage of dialkyl disulfides  Application of the Michael addition of thiolate anions to conjugated carbonyl compounds and regioselective ring opening of epoxides
Authors: Ranu Brindaban C , Mandal Tanmay
Published: May 2006

Indium(I) iodide promotes cleavage of dialkyl disulfides generating thiolate anions that then undergo facile addition to α,β-unsaturated ketones, aldehydes, carboxylic esters, and nitriles under neutral conditions producing corresponding β-ketosulfides or β-cyanosulfides. This strategy has also been used for the regioselective nucleophilic ring opening of epoxides by thiolate anions in presence of indium(III) chloride producing corresponding β-hydroxyphenyl sulfides. The reactions are in general, very clean, high yielding, and reasonably fast. Thus, simple and convenient procedures for the synthesis of β-ketosulfides or β-cyanosulfides and β-hydroxyalkyl sulfides have been developed using this cleavage reaction.Key words: indium(I) iodide, Michael addition, β-ketosulfide, β-cyanosulfide, epoxide, β-hydroxy sulfide.
Interaction of peroxynitrite with myoglobin and hemoglobin
Authors: Kalinga Shivashankar
Published: May 2006

Peroxynitrite, a biological toxin produced in vivo by the nearly diffusion-controlled reaction of nitrogen monoxide with superoxide, can nitrate and oxidize various biomolecules. Modifications caused by peroxynitrite have been linked to many human diseases, in particular, increased levels of free or protein-bound 3-nitrotyrosine, a biomarker for peroxynitrite in vivo, have been detected in a variety of pulmonary and cardiovascular diseases as well as in neurodegenerative and chronic inflammatory disorders. These observations have led to the search for a drug that can scavenge this powerful nitrating and oxidizing agent. Heme proteins, in particular myoglobin and hemoglobin, present in large amounts in muscles and red blood cells, respectively, have been proposed to serve as sinks for peroxynitrite in these cells. This report reviews the current knowledge of the reactions of different forms of myoglobin and hemoglobin with peroxynitrite and discusses their physiological role on the basis of measured rate constants.Key words: myoglobin, hemoglobin, peroxynitrite, tyrosine nitration, iron(III) peroxynitrite complex.
A novel and green version of the Passerini reaction in an ionic liquid ([bmim][BF4])
Authors: Fan Xuesen , Li Yanzhen , Zhang Xinying , Qu Guirong , Wang Jianji
Published: May 2006

The Passerini three-component condensation among a carboxylic acid (1), an aldehyde or ketone (2), and an isocyanide (3) was carried out for the first time in an ionic liquid, [bmim][BF4], and a series of acyloxycarboxamides were obtained through this reaction. The method presented herein has the advantages of high efficiency, a greener nature, and a simple operational procedure. Moreover, the ionic liquid can be easily recovered and reused for several runs without obvious loss of efficiency.Key words: Passerini reaction, acyloxycarboxamides, ionic liquid, green synthesis.
UNIFIED DESCRIPTION OF CORRELATORS IN NON-GAUSSIAN PHASES OF HERMITIAN MATRIX MODEL
Authors: ALEXANDROV A. , MIRONOV A. , MOROZOV A.
Published: May 2006

Following the program, proposed in hep-th/0310113, of systematizing known properties of matrix model partition functions (defined as solutions to the Virasoro-like sets of linear differential equations), we proceed to consideration of non-Gaussian phases of the Hermitian one-matrix model. A unified approach is proposed for description of "connected correlators" in the form of the phase-independent "check-operators" acting on the small space of T-variables (which parametrize the polynomial W(z)). With appropriate definitions and ordering prescriptions, the multidensity check-operators look very similar to the Gaussian case (however, a reliable proof of suggested explicit expressions in all loops is not yet available, only certain consistency checks are performed).
MATTER INHERITANCE SYMMETRIES OF SPHERICALLY SYMMETRIC STATIC SPACE–TIMES
Authors: SHARIF M.
Published: May 2006

In this paper we discuss matter inheritance collineations by giving a complete classification of spherically symmetric static space–times by their matter inheritance symmetries. It is shown that when the energy–momentum tensor is degenerate, most of the cases yield infinite dimensional matter inheriting symmetries. It is worth mentioning here that two cases provide finite dimensional matter inheriting vectors even for the degenerate case. The nondegenerate case provides finite dimensional matter inheriting symmetries. We obtain different constraints on the energy–momentum tensor in each case. It is interesting to note that if the inheriting factor vanishes, matter inheriting collineations reduce to be matter collineations already available in the literature. This idea of matter inheritance collineations turn out to be the same as homotheties and conformal Killing vectors are for the metric tensor.
TRANSVERSE WARD–TAKAHASHI RELATION FOR THE FERMION–BOSON VERTEX TO ONE-LOOP ORDER
Authors: HE HAN-XIN , KHANNA F. C.
Published: May 2006

In this paper, the transverse Ward–Takahashi relation for the fermion–boson vertex in momentum space is derived in four-dimensional Abelian gauge theory. We show that, by a formal derivation, the transverse Ward–Takahashi relation to one-loop order is satisfied. We also calculate the transverse Ward–Takahashi relation to one-loop order in an arbitrary covariant gauge in the case of massless fermions and find that the result is exactly the same as we obtain in terms of the one-loop fermion–boson vertex calculated in perturbation theory by using Feynman rules. This provides an approach to determine the transverse part of the vertex.
SCALAR FIELD ENTROPY IN BRANE WORLD BLACK HOLES
Authors: NANDI K. K. , ZHANG Y.-Z. , BHADRA A. , MITRA P.
Published: May 2006

A semiclassical calculation of entropy of a scalar field in the background of a class of brane world black holes (BWBH) is carried out in the presence of a brick wall cutoff when the 5D-bulk induced "tidal charge" has generic or extreme values.
GENERALIZED COMPLEMENTARITY RELATIONS IN COMPOSITE QUANTUM SYSTEMS OF ARBITRARY DIMENSIONS
Authors: JAKOB MATTHIAS , BERGOU JÁNOS A.
Published: May 2006

Complementarity relations in composite bipartite quantum systems of arbitrary dimensions are proposed. Genuine bipartite quantum properties whose information content is quantified by the generalized concurrence mutually exclude the single-partite properties of the subsystems. The single-partite properties are determined by generalized predictabilities and visibilities, i.e. by the traditional concepts of wave-particle duality and define two complementary realities. These properties combined together are complementary to the generalized I-concurrence which quantifies genuine quantum correlations in n ⊗ m-dimensional bipartite systems. An important feature of the proposed quantitative complementarity relation is its upper bound which is given by a dimensional-dependent factor that exceeds unity in case of qudits with dimensionality d > 2. In d > 2-dimensional systems the information content can exceed one bit of information.
MEASUREMENTS AND CORRELATIONS IN TRI-PARTITE SYSTEMS
Authors: AHMAD ZUKARNAIN Z. , KONSTADOPOULOU A. , VOURDAS A.
Published: May 2006

A system comprised of three oscillators A, B and C is studied. The oscillators B and C are interacting with each other, while the oscillator A does not interact with any of them. At t = 0 the system is in the state ρAB(0) ⊗ ρC(0). Two examples in which ρAB(0) is in separable and entangled states, are considered. It is shown that the oscillators A, C become entangled and that a measurement in C whose result is communicated classically to A , affects the state of the oscillator A. The work studies how the collapse due to the measurement at C , affects the state of the oscillator A .
PATTERN FORMATION IN QUANTUM ENSEMBLES
Authors: FEDOROVA ANTONINA N. , ZEITLIN MICHAEL G.
Published: May 2006

We present a family of methods, analytical and numerical, which can describe behaviour in (non) equilibrium ensembles, both classical and quantum, especially in the complex systems, where the standard approaches cannot be applied. We demonstrate the creation of nontrivial (meta) stable states (patterns), localized, chaotic, entangled or decoherent, from basic localized modes in various collective models arising from the quantum hierarchy of Wigner-von Neumann-Moyal-Lindblad equations, which are the result of "wignerization" procedure of classical BBGKY hierarchy. We present the explicit description of internal quantum dynamics by means of exact analytical/numerical computations.
ENTROPY AND ENTANGLEMENT OF THE SUPERPOSITIONS OF DISPLACED FOCK STATES WITH A TWO-LEVEL ATOM
Authors: ABD AL-KADER GAMAL M.
Published: May 2006

The properties of the displaced Fock states (DFS's) superpositions are reviewed. The interaction of these states with a two-level atom in cavity with the presence of additional Kerr medium is studied. Exact general matrix elements of the time-dependent operators of a Jaynes-Cummings model (JCM), in the presence of a Kerr medium, with these states are derived. The atomic inversion and photon number distribution are discussed. The quantum entropy and the entanglement of the atom-field are investigated. The exact results are employed to perform a careful investigation of the temporal evolution of the entropy. The connection between the field entropy and the collapses and revivals of the atomic inversion has been established. The general conclusions reached are illustrated by numerical results.
CONTINUOUS VARIABLE QUANTUM KEY DISTRIBUTION USING POLARIZED COHERENT STATES
Authors: VIDIELLA-BARRANCO A. , BORELLI L. F. M.
Published: May 2006

We discuss a continuous variables method of quantum key distribution employing strongly polarized coherent states of light. The key encoding is performed using the variables known as Stokes parameters, rather than the field quadratures. Their quantum counterpart, the Stokes operators Ŝi ( i =1,2,3), constitute a set of non-commuting operators, being the precision of simultaneous measurements of a pair of them limited by an uncertainty-like relation. Alice transmits a conveniently modulated two-mode coherent state, and Bob randomly measures one of the Stokes parameters of the incoming beam. After performing reconciliation and privacy amplification procedures, it is possible to distill a secret common key. We also consider a non-ideal situation, in which coherent states with thermal noise, instead of pure coherent states, are used for encoding.
QUANTUM CIRCUIT FOR ENTANGLING PROBE
Authors: BRANDT HOWARD E.
Published: May 2006

The quantum circuit and design are given for an optimized entangling probe attacking the BB84 protocol of quantum key distribution and yielding maximum information to the probe. Probe photon polarization states become entangled with the signal states on their way between the legitimate transmitter and receiver.
INFORMATION-TECHNOLOGY APPROACH TO QUANTUM FEEDBACK CONTROL
Authors: DONG DAO-YI , ZHANG CHEN-BIN , CHEN ZONG-HAI , CHEN CHUN-LIN
Published: May 2006

Quantum control theory is profitably reexamined from the perspective of quantum information, two results on the role of quantum information technology in quantum feedback control are presented and two quantum feedback control schemes, teleportation-based distant quantum feedback control and quantum feedback control with quantum cloning, are proposed. In the first feedback scheme, the output from the quantum system to be controlled is fed back into the distant actuator via teleportation to alter the dynamics of system. The result theoretically shows that it can accomplish some tasks such as distant feedback quantum control that Markovian or Bayesian quantum feedback can not complete. In the second feedback strategy, the design of quantum feedback control algorithms is separated into a state recognition step, which gives "on-off" signal to the actuator through recognizing some copies from the cloning machine, and a feedback (control) step using another copies of cloning machine. A compromise between information acquisition and measurement disturbance is established, and this strategy can perform some quantum control tasks with coherent feedback.
4-VECTOR FIELDS AND INDEFINITE METRICS
Authors: DVOEGLAZOV VALERI V.
Published: May 2006

We generalize the Stueckelberg formalism in the (1/2, 1/2) representation of the Lorentz Group, see Ref. 1–2. We analize the problem of the mass generation and of the indefinite metrics from the modern viewpoints, see Ref. 3–4. Some relations to other modern-physics models are found.
QUANTIZED DETECTOR REPRESENTATION OF QUANTUM OPTICAL NETWORKS
Authors: JAROSZKIEWICZ GEORGE , RIDGWAY-TAYLOR JASON
Published: May 2006

We present a unified and algorithmic approach to the calculation of final state amplitudes for quantum optical networks of arbitrary size and complexity. We discuss networks consisting of coupled Mach-Zender interferometers, experiments conventionally described by the POVM approach, and two-photon interference experiments.
BETTING ON INTERFEROMETRIC PATHS AND PHASES USING TRANSLATIONAL-INTERNAL ENTANGLEMENT: THE GREEDY KING GAME
Authors: KOLÁŘ MICHAL , OPATRNÝ TOMÁŠ , BAR-GILL NIR , KURIZKI GERSHON
Published: May 2006

The behavior of translationally–internally entangled (TIE) states in an interferometer of the Mach–Zehnder type is studied, by means of a game whose results show that TIE states allow near-certain guessing of both path (corpuscular) and phase (wavelike) features, as opposed to conventional states that are constrained by standard complementarity.
A FORMAL PSEUDO REALISTIC MEASUREMENT OF ELECTROMAGNETIC FIELD UNCERTAINTY RELATIONS
Authors: SAAVEDRA LUIS GERARDO PEDRAZA
Published: May 2006

Bohr and Rosenfeld showed in 1933 that the order of magnitude of precision, in the measurement of the free quantum electromagnetic components imposed by their uncertainty relations, could be estimated with thought experiments. The ingenious article by Bohr and Rosenfeld describes the complicated measuring devices that would be needed, but does not include a graphic representation of these. Neither does it show the measurement of a magnetic component in a given space-time region, nor the measurement of two parallel magnetic components, nor the measurement of two non-parallel magnetic components, nor the parallel measurement of one magnetic and one electric component, nor the non-parallel measurement of one electric and one magnetic component, nor the non-parallel measurement of one magnetic and one electric component in two different space-time regions. This article covers these pending matters and the graphics of cases studied by them.
EVALUATION OF DECOHERENCE FOR QUANTUM COMPUTING ARCHITECTURES: QUBIT SYSTEM SUBJECT TO TIME-DEPENDENT CONTROL
Authors: SOLENOV DMITRY , PRIVMAN VLADIMIR
Published: May 2006

We present an approach that allows quantifying decoherence processes in an open quantum system subject to external time-dependent control. Interactions with the environment are modeled by a standard bosonic heat bath. We develop two unitarity-preserving approximation schemes to calculate the reduced density matrix. One of the approximations relies on a short-time factorization of the evolution operator, while the other utilizes expansion in terms of the system-bath coupling strength. Applications are reported for two illustrative systems: an exactly solvable adiabatic model, and a model of a rotating-wave quantum-computing gate function. The approximations are found to produce consistent results at short and intermediate times.
PARAMETRIC DOWN-CONVERSION IN PHOTONIC CRYSTAL WAVEGUIDES
Authors: WEIHS GREGOR
Published: May 2006

Photonic crystals create dramatic new possibilities for nonlinear optics. I suggest to use defect waveguides for the production of pairs of photons in order to achieve particular dispersion characteristics and potentially very high brightness. I identify two possible phase-matching schemes and discuss their properties and advantages.
TWO-ATOM ENTANGLEMENT ASSISTED BY AN EXTERNAL PULSED PUMPING
Authors: BURLAK G. N. , KLIMOV A. B.
Published: May 2006

We have studied the effect of external pumping on the dynamics of the entanglement of two two-level atoms interacting with a cavity mode. It is shown that a sequence of well detuned pulses of the classical field leads to the dynamical formation of an extended plateau-like zone of high level atomic entanglement with the duration much longer than the period of Rabi oscillations. The dissipation reduces the amplitude of the entanglement, however practically does not change the width of such zones.
TRANSLATIONAL ENTANGLEMENT BY COLLISIONS AND HALF-COLLISIONS
Authors: FISCH LIOR , TAL ASSAF , KURIZKI GERSHON
Published: May 2006

Here we aim at setting the principles of and quantifying translational entanglement by collisions and half-collisions. In collisions, the resonance width s and the initial phase-space distributions are shown to determine the degree of post-collisional momentum entanglement. Half-collisions (dissociation) are shown to yield different types of approximate EPR states. We analyse a feasible realization of translational EPR entanglement and teleportation via cold-molecule Raman dissociation and subsequent collisions, resolving both practical and conceptual difficulties it has faced so far.
COMPLEX RATIONAL NUMBERS IN QUANTUM MECHANICS
Authors: BENIOFF PAUL
Published: May 2006

A binary representation of complex rational numbers and their arithmetic is described that is not based on qubits. It takes account of the fact that 0s in a qubit string do not contribute to the value of a number. They serve only as place holders. The representation is based on the distribution of four types of systems, corresponding to +1, -1, +i, -i, along an integer lattice. Complex rational numbers correspond to arbitrary products of four types of creation operators acting on the vacuum state. An occupation number representation is given for both bosons and fermions.
QUANTUM THEORY AND GALOIS FIELDS
Authors: LEV FELIX M.
Published: May 2006

We discuss the motivation and main results of a quantum theory over a Galois field (GFQT). The goal of the paper is to describe main ideas of GFQT in a simplest possible way and to give clear and simple arguments that GFQT is a more natural quantum theory than the standard one.
ANGULAR MOMENTUM AND MUTUALLY UNBIASED BASES
Authors: KIBLER MAURICE R.
Published: May 2006

The Lie algebra of the group SU 2 is constructed from two deformed oscillator algebras for which the deformation parameter is a root of unity. This leads to an unusual quantization scheme, the {J2, Ur} scheme, an alternative to the familiar {J2, Jz} quantization scheme corresponding to common eigenvectors of the Casimir operator J2 and the Cartan operator Jz. A connection is established between the eigenvectors of the complete set of commuting operators {J2, Ur} and mutually unbiased bases in spaces of constant angular momentum.
UNCERTAINTY RELATIONS FOR A DEFORMED OSCILLATOR
Authors: RÉCAMIER JOSÉ , MOCHÁN W. LUIS , GORAYEB MARÍA , PAZ JOSÉ L. , JÁUREGUI ROCÍO
Published: May 2006

We construct a deformed oscillator whose energy spectra is similar to that of a Morse potential. We obtain a convenient algebraic representation of the displacement and the momentum of a Morse oscillator by expanding them in terms of deformed creation and annihilation operators and we compute their average values between approximate coherent states of the deformed oscillator, and we compare them to the results obtained using the exact Morse coordinate and momenta. Finally we evaluate the temporal evolution of the dispersion (Δx)(Δp) and show that these states are not minimum uncertainty states.
TALBOT EFFECT FOR DISPERSION IN LINEAR OPTICAL FIBERS AND A WAVELET APPROACH
Authors: ROSU H. C. , TREVIÑO J. P. , CABRERA H. , MURGUÍA J. S.
Published: May 2006

We shortly recall the mathematical and physical aspects of Talbot's self-imaging effect occurring in near-field diffraction. In the rational paraxial approximation, the Talbot images are formed at distances ζ = p/q, where p and q are coprimes, and are superpositions of q equally spaced images of the original binary transmission (Ronchi) grating. This interpretation offers the possibility to express the Talbot effect through Gauss sums. Here, we pay attention to the Talbot effect in the case of dispersion in optical fibers presenting our considerations based on the close relationships of the mathematical representations of diffraction and dispersion. Although dispersion deals with continuous functions, such as gaussian and supergaussian pulses, whereas in diffraction one frequently deals with discontinuous functions, the mathematical correspondence enables one to characterize the Talbot effect in the two cases with minor differences. In addition, we apply, for the first time to our knowledge, the wavelet transform to the fractal Talbot effect in both diffraction and fiber dispersion. In the first case, the self similar character of the transverse paraxial field at irrational multiples of the Talbot distance is confirmed, whereas in the second case it is shown that the field is not self similar for supergaussian pulses. Finally, a high-precision measurement of irrational distances employing the fractal index determined with the wavelet transform is pointed out.
LOCAL INVARIANTS AND PAIRWISE ENTANGLEMENT IN SYMMETRIC MULTIQUBIT SYSTEM
Authors: USHA DEVI A. R. , UMA M. S. , PRABHU R. , SUDHA
Published: May 2006

Pairwise entanglement properties of a symmetric multi-qubit system are analyzed through a complete set of two-qubit local invariants. Collective features of entanglement, such as spin squeezing, are expressed in terms of invariants and a classification scheme for pairwise entanglement is proposed. The invariant criteria given here are shown to be related to the recently proposed (Phys. Rev. Lett.95, 120502 (2005)) generalized spin squeezing inequalities for pairwise entanglement in symmetric multi-qubit states.
COHERENT STATES FOR THE FINITE su(2)-OSCILLATOR MODEL
Authors: VICENT LUIS EDGAR
Published: May 2006

A finite oscillator is a system that has a discrete and finite number of spatial positions and energy levels accessible. The su(2)-oscillator model takes the generators of the angular momentum su(2) algebra and, giving to each one a definite physical interpretation, provides a consistent mathematical description of a finite oscillator. This work searches an example of identification of generalized coherent states, within the collection of states and wavefunctions of the finite su(2) oscillator model.
FINITE SYSTEMS ON PHASE SPACE
Authors: WOLF KURT BERNARDO
Published: May 2006

This contribution summarizes work on finite, non-cyclic Hamiltonian systems —in particular the one-dimensional finite oscillator—, in conjunction with a Lie algebraic definition of the (meta-) phase space of finite systems, and a corresponding Wigner distribution function for the state vectors. The consistency of this approach is important for the strategy of fractionalization of a finite Fourier transform, and the contraction of finite unitary to continuous symplectic transformations of Hamiltonian systems.
STUDY OF CHARGE TRANSFER AND STRUCTURE FACTOR CALCULATION IN YTTERBIUM SELENIDE
Authors: ARIPONNAMMAL S. , RADHIKA S. , SIVAKUMAR P.
Published: May 2006

Charge transfer in Ytterbium Selenide ( YbSe ) is analyzed by using experimental and theoretical XRD data. The direction and amount of charge transfer are inferred by plotting and comparing the structure factors of the components. The charge transfer parameters thus obtained are 0.36ē from Yb to Se .
ELECTROLESS DEPOSITION OF Ni-P ALLOYS ON CENOSPHERES BY USING SILVER AS THE CATALYST
Authors: XU JIAN , XIONG WEIHAO , ZENG AIXIANG
Published: May 2006

Electroless deposition of Ni-P alloys on cenospheres is demonstrated in the present investigation. AgNO 3 is used as an activator to replace the conventional PdCl 2 activator and [Formula: see text] in the coating bath is used as the reducing agent to replace Sn 2+ in order to lower the overall cost of the coating process. The coated cenospheres are characterized by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDX) and powder X-ray diffraction (XRD). It shows that Ni-P alloys uniformly deposit on the surface of the cenospheres under experimental conditions. The possible mechanism of electroless Ni-P alloys coating of cenospheres by using silver as the catalyst is suggested.
SUPERCONDUCTING PROPERTIES AND ORIENTATION BEHAVIOR OF REBa2Cu3Oy (RE = Yb, Er, Sm, Nd and La) FILMS BY METAL-ORGANIC DEPOSITION
Authors: YOKOYAMA K. , KITA R. , MATSUMOTO K. , YOSHIDA Y. , MUKAIDA M. , HORII S. , ICHINOSE A.
Published: May 2006

We have investigated superconducting properties and orientation behavior of RE123 ( RE = Yb , Er , Sm , Nd and La ) films on MgO and SrTiO 3 substrates by metal-organic deposition technique using metal naphthenates. On MgO substrates, only Yb123 films showed superconducting transition with Tc( zero ) of 77.0 K and c-axis orientation with in-plane alignment. On SrTiO3 substrates, Yb123 , Er123 , Sm123 , Nd123 and La123 films showed c-axis orientation with in-plane alignment, and Tc( zero ) of 89.5 K, 89.7 K, 80.5 K, 85.0 K and 47.6 K, respectively. Sm123 and La123 films showed square and plate-like grains on MgO substrates, and relatively flat surface covered with well-grown grains on SrTiO 3 substrates.
Nucleotide regulation of the voltage-dependent nonselective cation conductance in murine colonic myocytes
Authors: Monaghan Kevin P. , Koh Sang Don , Ro Seungil , Yeom Jonghun , Horowitz Burton , Sanders Kenton M.
Published: May 2006

ATP is proposed to be a major inhibitory neurotransmitter in the gastrointestinal (GI) tract, causing hyperpolarization and smooth muscle relaxation. ATP activates small-conductance Ca2+-activated K+channels that are involved in setting the resting membrane potential and causing inhibitory junction potentials. No reports are available examining the effects of ATP on voltage-dependent inward currents in GI smooth muscle cells. We previously reported two types of voltage-dependent inward currents in murine proximal colonic myocytes: a low-threshold voltage-activated, nonselective cation current ( IVNSCC) and a relatively high-threshold voltage-activated (L-type) Ca2+current ( IL). Here we have investigated the effects of ATP on these currents. External application of ATP (1 mM) did not affect IVNSCCor ILin dialyzed cells. ATP (1 mM) increased IVNSCCand decreased ILin the perforated whole-cell configuration. UTP and UDP (1 mM) were more potent than ATP on IVNSCC. ADP decreased ILbut had no effect on IVNSCC. The order of effectiveness was UTP = UDP > ATP > ADP. These effects were not blocked by pyridoxal phosphate-6-azo(benzene-2,4-disulfonic acid) (PPADS), but the phospholipase C inhibitor U-73122 reversed the effects of ATP on IVNSCC. ATP stimulation of IVNSCCwas also reversed by protein kinase C (PKC) inhibitors chelerythrine chloride or bisindolylmaleimide I. Phorbol 12,13-dibutyrate mimicked the effects of ATP. RT-PCR showed that P2Y4is expressed by murine colonic myocytes, and this receptor is relatively insensitive to PPADS. Our data suggest that ATP activates IVNSCCand depresses ILvia binding of P2Y4receptors and stimulation of the phospholipase C/PKC pathway.
PGC-1α and PGC-1β have both similar and distinct effects on myofiber switching toward an oxidative phenotype
Authors: Mortensen Ole Hartvig , Frandsen Lis , Schjerling Peter , Nishimura Erica , Grunnet Niels
Published: May 2006

Peroxisome proliferator-activated receptor-γ coactivator-1α and -1β (PGC-1α and PGC-1β) were overexpressed by adenovirus-mediated gene transfer in cultures of primary rat skeletal muscle cells derived from neonatal myoblasts. Effects on muscle fiber type transition and metabolism were studied from days 5 to 22 of culture. PGC-1α and PGC-1β overexpression caused a three- to fourfold increase in mRNA level, a doubling of enzymatic activity of citrate synthase, a slight increase in short-chain acyl-CoA dehydrogenase mRNA, a doubling of the mRNA level, and a 30–50% increase in enzymatic activity of glyceraldehyde-3-phosphate dehydrogenase. Lactate dehydrogenase or creatine kinase activity was unchanged. PGC-1α enhanced glycogen buildup twofold at 5 or 25 mM glucose, whereas PGC-1β caused a decrease. Both PGC-1α and PGC-1β overexpression caused a faster maturation of myotubes, as seen by mRNA downregulation of the immature embryonal and perinatal myosin heavy-chain (MHC) isoforms. PGC-1α or PGC-1β overexpression enhanced mRNA of the slow oxidative-associated MHC isoform MHCIb and downregulated mRNA levels of the fast glycolytic-associated MHC isoforms MHCIIX and MHCIIB. Only PGC-1β overexpression caused an increase in mRNA of the intermediary fast oxidative-associated MHC isoform MHCIIA. PGC-1α or PGC-1β overexpression upregulated GLUT4 mRNA and downregulated myocyte enhancer factor 2C transcription factor mRNA; only PGC-1α overexpression caused an increase in the mRNA expression of TRB3, a negative regulator of insulin signaling. These results show that both PGC-1α and PGC-1β are involved in the regulation of skeletal muscle fiber transition and metabolism and that they have both overlapping and differing effects.
Transforming growth factor-β1differentially mediates fibronectin and inflammatory cytokine expression in kidney tubular cells
Authors: Qi Weier , Chen Xinming , Holian John , Mreich Ellein , Twigg Stephen , Gilbert Richard E. , Pollock Carol A.
Published: May 2006

Transforming growth factor-β1(TGF-β1) is not only an important fibrogenic but also immunomodulatory cytokine in the human kidney. We have recently demonstrated that TGF-β1induces interleukin-8 (IL-8), macrophage chemoattractant protein-1 (MCP-1), and fibronectin production in renal proximal tubular (HK-2) cells. However, the unique dependence of IL-8, MCP-1, and fibronectin on TGF-β1expression is unknown. The TGF-β1gene was effectively silenced in HK-2 cells using small-interference (si) RNA. Basal secretion of IL-8 and MCP-1 decreased (both P < 0.05) but, paradoxically, fibronectin increased ( P < 0.05) in TGF-β1-silenced cells compared with cells transfected with nonspecific siRNA. Significant increases were observed in mRNA for the TGF-β2( P < 0.05), TGF-β3( P < 0.05) isoforms and pSmad2 ( P < 0.05), which were reflected in protein expression. Concurrent exposure to pan-specific TGF-β antibody reversed the observed increase in fibronectin expression, suggesting that TGF-β2and TGF-β3isoforms mediate the increased fibronectin expression in TGF-β1-silenced cells. An increase in the DNA binding activity of activator protein-1 (AP-1; P < 0.05) was also observed in TGF-β1-silenced cells. In contrast, nuclear factor-κB (NF-κB) DNA binding activity was significantly decreased ( P < 0.0005). These studies demonstrate that TGF-β1is a key regulator of IL-8 and MCP-1, whereas fibronectin expression is regulated by a complex interaction between the TGF-β isoforms in the HK-2 proximal tubular cell line. Decreased expression of TGF-β1reduces chemokine production in association with reduced NF-κB DNA binding activity, suggesting that immunomodulatory pathways in the kidney are specifically dependent on TGF-β1. Conversely, decreased expression of TGF-β1results in increased TGF-β2, TGF-β3, AP-1, and pSmad2 that potentially mediates the observed increase in fibronectin.
Disinhibitory pathways for control of sodium transport: regulation of ENaC by SGK1 and GILZ
Authors: Bhalla Vivek , Soundararajan Rama , Pao Alan C. , Li Hongyan , Pearce David
Published: May 2006

Regulation of ENaC occurs at several levels. The principal hormonal regulator of ENaC, aldosterone, acts through the mineralocorticoid receptor to modulate ENaC-mediated sodium transport, and considerable attention has focused on defining the components of the early phase of this response. Two genes, SGK1 and GILZ, have now been implicated in this regulation. While the functional significance of SGK1 in mediating aldosterone effects is well established, new evidence has enhanced our understanding of the mechanisms of SGK1 action. In addition, recent work demonstrates a novel role for GILZ in the stimulation of ENaC-mediated sodium transport. Interestingly, both SGK1 and GILZ appear to negatively regulate tonic inhibition of ENaC and thus use disinhibition to propagate the rapid effects of aldosterone to increase sodium reabsorption in tight epithelia.
Auditory Cortical Responses to Electrical Stimulation of the Inferior Colliculus: Implications for an Auditory Midbrain Implant
Authors: Lim Hubert H. , Anderson David J.
Published: May 2006

The success and limitations of cochlear implants (CIs) along with recent advances in deep brain stimulation and neural engineering have motivated the development of a central auditory prosthesis. In this study, we investigated the effects of electrical stimulation of the inferior colliculus central nucleus (ICC) on primary auditory cortex (A1) activity to determine the potential benefits of an auditory midbrain implant (AMI). We recorded multiunit activity in A1 of ketamine-anesthetized guinea pigs in response to single-pulse (200 μs/phase) monopolar stimulation of the ICC using multisite silicon-substrate probes. We then compared measures of threshold, dynamic range, and tonotopic spread of activation for ICC stimulation with that of published data for CI stimulation. Our results showed that compared with cochlear stimulation, ICC stimulation achieved: 1) thresholds about 8 dB lower; 2) dynamic ranges ≥4 dB greater; and 3) more localized, frequency-specific activation, even though frequency specificity was partially lost at higher stimulus levels for low-frequency ICC regions. Our results also showed that stimulation of rostral ICC regions elicited lower thresholds but with greater activation spread along the tonotopic gradient of A1 than did stimulation of more caudal regions. These results suggest that an AMI may improve frequency and level coding with lower energy requirements compared with CIs. However, a trade-off between lower perceptual thresholds and better frequency discrimination may exist that depends on location of stimulation along the caudorostral dimension of the ICC. Overall, this study provides the foundation for future AMI research and development.