bluuebunny/crossref_metadata_2025 huggingface dataset:
Aurintricarboxylic Acid Inhibits the Early Stage of Vaccinia Virus Replication byTargeting both Cellular and Viral Factors
Authors: Myskiw Chad , Deschambault Yvon , Jefferies Kristel , He Runtao , Cao Jingxin
Published: December 2006

Aurintricarboxylic acid (ATA) has been shown to inhibit the replication of viruses from several different families, including human immunodeficiency virus, vesicular stomatitis virus, and the coronavirus causing severe acute respiratory syndrome. This study characterizes the inhibitory effect of ATA on vaccinia virus replication in HeLa, Huh7, and AD293 cells. Vaccinia virus replication is significantly abrogated upon ATA treatment, which is associated with the inhibition of early viral gene transcription. This inhibitory effect may be attributed to two findings. First, ATA blocks the phosphorylation of extracellular signal-regulated kinase 1/2, an event shown to be essential for vaccinia virus replication. Second, ATA inhibits the phosphatase activity of the viral enzyme H1L, which is required to initiate viral transcription. Thus, ATA inhibits vaccinia virus replication by targeting both cellular and viral factors essential for the early stage of replication.
Sequence-Independent Targeting of Transmembrane Proteins Synthesized within Vaccinia Virus Factories to Nascent Viral Membranes
Authors: Husain Matloob , Weisberg Andrea S. , Moss Bernard
Published: December 2006

The primary membrane of vaccinia virus, as well as those of other
poxviruses, forms within a discrete cytoplasmic factory region. We
recently determined the existence of an operative pathway from the
endoplasmic reticulum within the virus factory to nascent viral
membranes and demonstrated that a viral protein could be diverted from
this pathway to Golgi membranes by the addition of COPII-binding sites
(M. Husain, A. S. Weisberg, and B. Moss, Proc. Natl. Acad.
Sci. USA,
103:
19506-19511, 2006). Here we describe an
investigation of the structural features that are required for transit
of proteins to the viral membrane. Deletion of either the N-terminal
domain or the C-terminal cytoplasmic tail from the conserved A9 protein
did not prevent its incorporation into viral membranes, whereas
deletion of the transmembrane domain resulted in its distribution
throughout the cytoplasm. Nevertheless, replacement of the A9
transmembrane domain with the corresponding region of a nonpoxvirus
transmembrane protein or of a vaccinia virus extracellular envelope
protein allowed viral membrane targeting, indicating no requirement for
a specific amino acid sequence. Remarkably, the epitope-tagged A9
transmembrane domain alone, as well as a heterologous transmembrane
domain lacking a poxvirus sequence, was sufficient for viral membrane
association. The data are consistent with a sequence-independent
pathway in which transmembrane proteins that are synthesized within the
virus factory and lack COPII or other binding sites that enable
conventional endoplasmic reticulum exiting are incorporated into
nascent viral
membranes.
The Fitness Cost of Mutations Associated with Human Immunodeficiency Virus Type 1 Drug Resistance Is Modulated by Mutational Interactions
Authors: Cong Mian-er , Heneine Walid , García-Lerma J. Gerardo
Published: December 2006

It is generally accepted that the fitness cost of resistance mutations plays a role in the persistence of transmitted drug-resistant human immunodeficiency virus type 1 and that mutations that confer a high fitness cost are less able to persist in the absence of drug pressure. Here, we show that the fitness cost of reverse transcriptase (RT) mutations can vary within a 72-fold range. We also demonstrate that the fitness cost of M184V and K70R can be decreased or enhanced by other resistance mutations such as D67N and K219Q. We conclude that the persistence of transmitted RT mutants might range widely on the basis of fitness and that the modulation of fitness cost by mutational interactions will be a critical determinant of persistence.
Prevalence and Abundance of Latently Transcribed Varicella-Zoster Virus Genes in Human Ganglia
Authors: Cohrs Randall J. , Gilden Donald H.
Published: December 2006

In human ganglia latently infected with varicella-zoster virus (VZV), sequence analysis has revealed that five viral genes (VZV genes 21, 29, 62, 63, and 66) are transcribed. However, their comparative prevalence and abundance are unknown. Here, using real-time PCR, we analyzed 28 trigeminal ganglia from 14 humans for RNA corresponding to the five virus genes known to be transcribed in latently infected human ganglia. The most prevalent transcript found was VZV gene 63 (78%), followed by gene 66 (43%), gene 62 (36%), and gene 29 (21%). No gene 21 transcripts were detected in any of the 28 ganglia. VZV gene 63 RNA was also the most abundant (3,710 ± 6,895 copies per 1 μg of mRNA) transcript detected in latently infected human ganglia, followed by VZV gene 29 (491 ± 594), VZV gene 66 (117 ± 85), and VZV gene 62 (64 ± 38). Thus, the repeated detection and high abundance of VZV gene 63 transcripts in latently infected ganglia suggests that VZV gene 63 may be more important for the maintenance of virus latency than the less abundantly transcribed and randomly detected VZV genes 21, 29, 62, and 66.
ATTRACTOR BEHAVIOR IN DILATONIC (PHANTOM) DARK ENERGY MODEL WITH POTENTIAL [1+(σ-A)2]e-Bσ
Authors: HUANG Z. G. , LU H. Q. , FANG W.
Published: December 2006

In this paper, we consider the dilatonic dark energy model and its phantom model. Based on the dilatonic (phantom) model, we take the potential of dilaton field of the form [1+(σ-A)2]e-Bσ which seems to connect with ideas from M-theory, and analyze the sufficient condition for the existence of attractor solution. We find that the behavior of the attractor is not sensitive to the initial condition, thus the fine-tuning problem is alleviated. By numerical analysis, we investigate the asymptotic behavior of the attractor, which corresponds to an equation of state ω = -1 and a cosmic density parameter Ωσ = 1.
COMMUTATOR ANOMALY IN NONCOMMUTATIVE QUANTUM MECHANICS
Authors: DULAT SAYIPJAMAL , LI KANG
Published: December 2006

In this paper, the Schrödinger equation on noncommutative phase space is given by using a generalized Bopp's shift. Then the anomaly term of commutator of arbitrary physical observable operators on noncommutative phase space is obtained. Finally, the basic uncertainty relations for space–space and space–momentum as well as momentum–momentum operators in noncommutative quantum mechanics (NCQM), and uncertainty relation for arbitrary physical observable operators in NCQM are discussed.
CAUSAL PROPAGATION OF SPIN-CASCADES
Authors: RICO L. M. , KIRCHBACH M.
Published: December 2006

We gauge the direct product of the Proca with the Dirac equation that describes the coupling to the electromagnetic field of the spin-cascade (1/2, 3/2) residing in the four-vector spinor ψμ and analyze propagation of its wave fronts in terms of the Courant–Hilbert criteria. We show that the differential equation under consideration is unconditionally hyperbolic and the propagation of its wave fronts unconditionally causal. In this way we prove that the irreducible spin-cascade embedded within ψμ is free from the Velo–Zwanziger problem that plagues the Rarita–Schwinger description of spin-3/2. The proof extends also to the direct product of two Proca equations and implies causal propagation of the spin-cascade (0, 1, 2) within an electromagnetic environment.
STRONG-COUPLING GAUGE THEORY OF NODAL SPINONS AND ANTIFERROMAGNETIC LONG-RANGE ORDER
Authors: ICHINOSE IKUO
Published: December 2006

In this paper we shall study a gauge theory of nodal spinons which appears as a low-energy effective theory for antiferromagnetic (AF) Heisenberg models. In most of the studies on the nodal spinons given so far, the gauge interaction between spinons was assumed weak and nonperturbative effects like instantons and vortices were ignored. In this paper, we shall study strong-coupling gauge theory of nodal spinons and reveal its nontrivial phase structure. To this end, we employ recently developed lattice gauge theory techniques for studying finite-temperature and finite-density gauge theory. At low temperature and low spinon-density region, an AF long-range order exists. As temperature and/or density of spinons increase, a phase transition to nonmagnetic phase takes place. Order of the phase transition is of second (first) order for low (high) density region of spinons. At a quantum critical point at vanishing temperature T = 0, abrupt change of spinon density occurs as a function of the chemical potential. Implications of the results to the heavy-fermion materials and the high-T c cuprates are discussed.
SUITABILITY OF A4 AS A FAMILY SYMMETRY IN GRAND UNIFICATION
Authors: MA ERNEST
Published: December 2006

In the recent successful applications of the non-Abelian discrete symmetry A4 to the tribimaximal mixing of neutrinos, lepton doublets and singlets do not transform in the same way. It thus appears to be unsuitable as a family symmetry in grand unification. A simple resolution of this dilemma is proposed.
RADIATION AND POTENTIAL BARRIERS OF A 5D BLACK STRING SOLUTION
Authors: LIU MOLIN , LIU HONGYA , XU LIXIN , WESSON PAUL S.
Published: December 2006

By using a massless scalar field we examine the effect of an extra dimension on black hole radiation. As the equations are coupled, we find that the structure of the fifth dimension (as for membrane and induced-matter theory) affects the nature of the radiation observed in four-dimensional spacetime. In the case of the Schwarzschild–de Sitter solution embedded in a Randall–Sundrum brane model, the extension of the black hole along the fifth dimension looks like a black string. Then it is shown that, on the brane, the potential barrier surrounding the black hole has a quantized as well as a continuous spectrum. In principle, Hawking radiation may thus provide a probe for higher dimensions.
CURRENT PHYSICS RESULTS FROM STAGGERED CHIRAL PERTURBATION THEORY
Authors: AUBIN C.
Published: December 2006

We review several results that have been obtained using lattice QCD with the staggered quark formulation. Our focus is on the quantities that have been calculated numerically with low statistical errors and have been extrapolated to the physical quark mass limit and continuum limit using staggered chiral perturbation theory. We limit our discussion to a brief introduction to staggered quarks, and applications of staggered chiral perturbation theory to the pion mass, decay constant, and heavy–light meson decay constants.
A FAST ALGORITHM FOR STALLINGS' FOLDING PROCESS
Authors: TOUIKAN NICHOLAS W. M.
Published: December 2006

Stalling's folding process is a key algorithm for solving algorithmic problems for finitely generated subgroups of free groups. Given a subgroup H = 〈J1,…,Jm〉 of a finitely generated nonabelian free group F = F(x1,…,xn) the folding porcess enables one, for example, to solve the membership problem or compute the index [F : H]. We show that for a fixed free group F and an arbitrary finitely generated subgroup H (as given above) we can perform the Stallings' folding process in time O(N log *(N)), where N is the sum of the word lengths of the given generators of H.
ALGORITHM FOR MULTIPLYING SCHUBERT CLASSES
Authors: DUAN HAIBAO , ZHAO XUEZHI
Published: December 2006

Based on the formula for multiplying Schubert classes obtained in [17], we develop an algorithm computing the product of two arbitrary Schubert classes in a flag manifold G/H, where G is a compact connected Lie group and H ⊂ G is the centralizer of a one-parameter subgroup in G.

Since all Schubert classes on G/H constitute a basis for the integral cohomology H*(G/H), the algorithm gives also a method to compute the integral cohomology ring H*(G/H) independent of the classical spectral sequence method of Leray and Borel [32, 33, 8, 9].
FINE BRUHAT INTERSECTIONS FOR REDUCTIVE MONOIDS
Authors: TAYLOR DEWEY T.
Published: December 2006

This paper concerns Bruhat intersections for a reductive monoid M. A comparison is made to the known results for Bruhat intersections for a reductive group G.
GENERALIZED M*-GROUPS
Authors: SAHIN RECEP , IKIKARDES SEBAHATTIN , KORUOGLU OZDEN
Published: December 2006

A compact bordered Klein surface of algebraic genus p ≥ 2 has at most 12(p-1) automorphisms. Automorphism groups which attain this bound are called M*-groups. In this paper, firstly, we define generalized M*-groups. Then, we show that there is a relationship between the extended Hecke groups and generalized M*-groups. Finally, we prove that a generalized M*-groups G is supersoluble if and only if |G| = 4 · qr for q ≥ 3 prime number and for some positive integer r.
QUASI-SURE EXISTENCE OF BROWNIAN ROUGH PATHS AND A CONSTRUCTION OF BROWNIAN PANTS
Authors: INAHAMA YUZURU
Published: December 2006

In this paper we will prove the quasi-sure existence of the Brownian rough path for finite-dimensional cases. As an application we will give a construction of Brownian pants, that is a certain continuous process on the continuous loop space over a compact manifold.
GAUSSIAN FLUCTUATIONS OF REPRESENTATIONS OF WREATH PRODUCTS
Authors: ŚNIADY PIOTR
Published: December 2006

We study the asymptotics of the reducible representations of the wreath products G≀Sq = Gq ⋊ Sq for large q, where G is a fixed finite group and Sq is the symmetric group in q elements; in particular for G = ℤ/2ℤ we recover the hyperoctahedral groups. We decompose such a reducible representation of G≀Sq as a sum of irreducible components (or, equivalently, as a collection of tuples of Young diagrams) and we ask what is the character of a randomly chosen component (or, what are the shapes of Young diagrams in a randomly chosen tuple). Our main result is that for a large class of representations, the fluctuations of characters (and fluctuations of the shape of the Young diagrams) are asymptotically Gaussian. The considered class consists of the representations for which the characters asymptotically almost factorize and it includes, among others, the left regular representation therefore we prove the analogue of Kerov's central limit theorem for wreath products.
RENORMALISATION DU TEMPS LOCAL DES POINTS TRIPLES DU MOUVEMENT BROWNIEN
Authors: JENANE R. , HACHAICHI R. , STREIT L.
Published: December 2006

We show that each term of the multiple Wiener integral expansion for the renormalized triple self-intersection local time of higher dimensional Brownien motion converges in law to an independent Brownian motion.
THE INDEX OF (WHITE) NOISES AND THEIR PRODUCT SYSTEMS
Authors: SKEIDE MICHAEL
Published: December 2006

Almost every paper about Arveson systems (i.e. product systems of Hilbert spaces) starts by recalling their basic classification assigning to every Arveson system a type and an index. So it is natural to ask in how far an analogue classification can also be proposed for product systems of Hilbert modules. However, while the definition of type is plain, there are obstacles for the definition of index. But all obstacles can be removed when restricting to the category which we introduce here as spatial product systems and that matches the usual definition of spatial in the case of Arveson systems. This is not really a loss because the definition of index for nonspatial Arveson systems is rather formal and does not reflect the information the index carries for spatial Arveson systems.

E0-semigroups give rise to product systems. Our definition of spatial product system, namely, existence of a unital unit that is central, matches Powers' definition of spatial in the sense that the E0-semigroup from which the product system is derived admits a semigroup of intertwining isometries. We show that every spatial product system contains a unique maximal completely spatial subsystem (generated by all units) that is isomorphic to a product system of time ordered Fock modules. (There exist nonspatial product systems that are generated by their units. Consequently, these cannot be Fock modules.) The index of a spatial product system we define as the (unique) Hilbert bimodule that determines the Fock module. In order to show that the index merits the name index we provide a product of product systems under which the index is additive (direct sum). While for Arveson systems there is the tensor product, for general product systems the tensor product does not make sense as a product system. Even for Arveson systems our product is, in general, only a subsystem of the tensor product. Moreover, its construction depends explicitly on the choice of the central reference units of its factors.

Spatiality of a product system means that it may be derived from an E0-semigroup with an invariant vector expectation, i.e. from a noise. We extend our product of spatial product systems to a product of noises and study its properties.

Finally, we apply our techniques to show the module analogue of Fowler's result that free flows are comletely spatial, and we compute their indices.
Post-Takeover Effects on Thai Bidding Firms: Are Takeovers in the Bidder's Interests?
Authors: Allen D. E. , Soongswang A.
Published: December 2006

This paper analyses takeover effects on the Thai stock market in terms of their impact on the bidding firms' shareholders. We apply a comprehensive analysis of shareholder wealth effects using multiple methods. Our results conform with prior studies: see Jensen and Ruback (1983), Agrawal and Jaffe (1999), Bruner (2002) and Campa and Hernando (2004). Thai takeovers result in significant negative abnormal returns over the sixteen months after the takeover. The abnormal returns, variously defined, vary from -4% to -6%, and -0.20% (monthly) for the bidding firm's shareholders. Thai takeovers do not appear to add to bidding firms' shareholder wealth.
Discounted Private Placements in New Zealand: Exploitation or Fair Compensation?
Authors: Anderson Hamish D.
Published: December 2006

Market commentators have suggested that New Zealand's lax private placement and disclosure regulation allows private placement purchasers to immediately sell discounted shares without disclosing these transactions to the market. However, New Zealand firms with the deepest discounts tend to have higher risks, lower returns and higher costs associated with evaluating firm value. Therefore, the possibility that deep discounts may simply represent adequate compensation for the extra risk and cost private placement purchasers incur cannot be ruled out. In this respect private placement purchasers in New Zealand take on the role and risks associated with investment banker and underwriter.
The Cross Section of Expected Returns and Amortized Spreads
Authors: He Zhongzhi Lawrence , Kryzanowski Lawrence
Published: December 2006

The cross-sectional relationship between expected returns and amortized spreads is studied in an overlapping-generations economy with an average investor. The commonality in liquidity is directly incorporated into the asset-pricing relation. In a static equilibrium, the amortized spread of an asset is related to its expected return through four channels; namely: the equilibrium zero-beta rate, the market risk premium, a level effect, and an incremental sensitivity effect. Although both are present over the entire period, their relative importance shifts from a significant level to a significant sensitivity effect from the earlier to most recent sub-period in the Canadian stock market.
Price Expectation and the Pricing of Stock Index Futures: Evidence from Developed and Emerging Markets
Authors: Wang Janchung , Hsu Hsinan
Published: December 2006

This study examines how well the pricing model of Hsu and Wang (2004) explains the behavior of stock index futures prices for the developed markets (such as the S&P 500 index futures market) and the emerging markets (such as the Taiwan Futures Exchange (TAIFEX) Taiwan stock index futures market). It also compares the pricing performance of three alternative pricing models of stock index futures: the cost of carry model, the Hemler and Longstaff (1991) model, and the Hsu–Wang model. Overall, the Hsu–Wang model provides significantly better pricing performance than that of the cost of carry model in emerging markets with high degrees of imperfection. Moreover, this study also observes that the Hemler and Longstaff (1991) model performs better than the cost of carry model in estimating prices of the TAIFEX futures, suggesting that the incorporation of stochastic market volatility is beneficial to predict the TAIFEX futures prices.
The Informative Content of the Net-Buy Information of Institutional Investors in the Taiwan Stock Market: A Revisit Using Conditional Analysis
Authors: Chiao Chaoshin , Cheng David C. , Shao Yunju
Published: December 2006

Chiao and Lin (2004) argue that the strategies following the investment pace of security investment trust companies (SITCs) are more profitable than the market and those following foreign investors (FIs) and security dealers (SDs) in the Taiwan stock market. We reexamine their results under various market events and economic states. Employing the close-to-close returns, our results are mostly consistent with Chiao and Lin (2004) except that, during the period of economic recovery, following FIs is more profitable. However, employing the open-to-close returns and considering transaction costs, none of the strategies are profitable.
ON ASYMMETRY OF THERMAL CURRENT FLUCTUATIONS
Authors: GRAFOV B. M.
Published: December 2006

The noise circuit theory is used to analyze the asymmetry (skewnees) of thermal current fluctuations in the equilibrium nonlinear LR-circuit. We prove that the asymmetry of thermal current fluctuations at the inductor depends on the resistance nonlinearity and is independent of the inductance nonlinearity. A comparison between results of noise circuit theory and results of Gibbs statistical ensemble method shows that the Gibbs statistical ensemble method does not work when one is interested in calculating the nonlinear thermal fluctuations.
DEFECT-LINE DYNAMICS IN OSCILLATORY SPIRAL WAVES
Authors: WU STEVEN
Published: December 2006

We study defect-line dynamics in a 2-D spiral-wave pair in the Rössler model for its underlying local dynamics in period-N and chaotic regimes with a single bifurcation parameter κ. We find that a spiral wave pair is always stable across the period-doubling cascade and in the chaotic regime. When N ≥ 2 defect lines appear spontaneously and a loop exchange occurs across the defect line. There exists a "critical point" κ c below and above which the time-averaged total length of defect lines L converges to almost constant but different values L1 and L2. When κ > κ c defect lines show large fluctuations due to creation and annihilation processes.
A COMPARATIVE STUDY OF AN ANALOGUE OPTICAL FOURIER TRANSFORM QUANTUM COMPUTER WORKING IN ENTANGLEMENT AND NON-ENTANGLEMENT MODE
Authors: HESZLER P.
Published: December 2006

A gedanken model of an analog optical computer for general purpose Fourier transform tasks is built and studied assuming entangled or non-entangled photons appearing at the input. The performance of the entangled and non-entangled operation modes, regarding information content, power consumption, acquisition time, wavelength and bandwidth limitations are analyzed as function of qubit repetition rate and number of qubits in the entangled state, respectively, based on fundamental physical laws. The total number of input photons is assumed the same for the two operation modes. It is sown that the entangled mode outperforms the non-entangled one, but only above a certain number of qubits in the entangled state. It is argued that, for practical applications to general purpose computing, several limitations should be imposed regarding qubit repetition rate and number of qubits in the entangled state. In addition, it is pointed out that the conclusions that we present are equally valid for general purpose optical quantum computing and for quantum information processing, too.
SMOOTHNESS OF WEAK SOLUTIONS OF THE SPATIALLY HOMOGENEOUS LANDAU EQUATION
Authors: EL SAFADI MOUHAMAD
Published: December 2006

We prove that any weak solution (in the sense of Desvillettes and Villani [6]) to the Landau homogeneous equation is smooth and, in particular, that it lies in Schwartz space [Formula: see text]. Our result has to be compared to [6], where Desvillettes and Villani have shown existence of smooth weak solutions along with a uniqueness result, under further assumptions on initial data. Our method of proof uses the Littlewood–Paley decomposition of velocity space, and elementary Cauchy–Schwarz or Young's inequalities, thus avoiding any use of complex Sobolev interpolation inequalities.
ANALYTICITY OF SURVIVAL PROBABILITY FOR CONTACT PROCESS AROUND t = 0
Authors: BELITSKY VLADIMIR , HIGUCHI YASUNARI , KONNO NORIO , SUGIMINE NOBUAKI
Published: December 2006

The contact process is a simple model for the spread of epidemics with an infection rate λ and has become one of the most prominent models to show a phase transition even in one dimension. The transition is characterized by the behavior of its survival probability at time t, ρ(t). Clarifying how ρ(t) depends on λ and t is one of the interesting problems in studying the process. In the present paper, we show that the power series expansion of ρ(t) at t = 0 is entirely analytic. We also prove that the coefficients of this power series form an alternate sequence. To our knowledge, no result is known on the analyticity of ρ(t) in t = 0 except the first author's previous result in 1995. Our paper extends the result to a more general setting by using a different method.
PHOTON TRANSPORT PROBLEMS INVOLVING A POINT SOURCE
Authors: BELLENI-MORANTE A. , LAMB W. , McBRIDE A. C.
Published: December 2006

We consider both a direct and an inverse problem of photon transport in an interstellar cloud with a point photon source. By using a non-rigorous (but physically reasonable) procedure, we prove that the direct problem has a unique solution and that the inverse problem also has a unique solution, under the assumptions that a single value of the photon far-field is known and the scattering cross-section is suitably small. Finally, we show in a rigorous way that the direct problem has a unique distributional solution if the point source is modelled by a Dirac δ functional.
THE ANALYSIS OF BINDING PATTERNS ON DIFFERENT RECEPTORS BOUND TO HEMAGGLUTININ OF AVIAN AND AVIAN-LIKE INFLUENZA VIRUS USING QUANTUM CHEMICAL CALCULATIONS
Authors: SANGMA C. , NUNRIUM P. , HANNONGBUA S.
Published: December 2006

While there has been no pandemic outbreak of influenza evolving from the H5N1 strain yet, the virus has already killed people. This suggests that without any significant mutations the influenza virus can live within the human body for days in which its life cycles can continue. The first step for infection is the host cell surface binding which is the function of the glycoprotein hemagglutinin (HA). In this investigation, quantum chemical calculations were performed on the systems comprising four structures coming from parts of the HA, with its cell receptor-analog substrate, determined from X-ray structures of the 1934 Spanish flu and avian influenza antigens. The calculations are aimed at partitioning the system into several parts, thus obtaining global and partial contributions of binding energy from each of them. As a result, it was possible to propose quantitatively the main contributions of key amino residues of the avian influenza virus glycoprotein around the binding pocket relevant to the binding process.

The main binding energy contributions of the Spanish flu HA were from Tyr95, Val135, Thr136, Ala137, Glu190, Asp225, and Gln226, while the main contributions of the avian flu HA were from Ser129, Val131, Ser132, and Ser133. It was also found that the effect from the HA with an avian characteristic, Gln226 and Gly228, was not relatively high according to the contributed binding energy, whereas the effect from nearby water molecules was significant. Thus, it was concluded that both human and avian virus HA could recognize human cell receptors better than the avian cell receptors according to the binding energy. Therefore, the preference to any particular cell receptor types might involve some other factors rather than being determined solely by the HA binding process.
REGIOSELECTIVITY OF HETERO DIELS–ALDER REACTIONS BETWEEN 1-AZA-1,3-BUTADIENE DERIVATIVES AND DIMETHYLVINYLAMINE: A THEORETICAL INVESTIGATION
Authors: CHEMOURI HAFIDA , BENCHOUK WAFAA , MEKELLECHE SIDI MOHAMED
Published: December 2006

The regioselectivity of hetero Diels–Alder reactions between 1-aza-1,3-butadiene derivatives and dimethylvinylamine is elucidated by means of several theoretical approaches, namely, the Gazquez–Mendez rule based on the calculation of local softnesses, barrier activation calculations, maximum hardness principle, and the Houk rule based on the FMO theory. The calculations were performed at the B3LYP/6-31G(d) level of theory, and the obtained results are in agreement with available experimental results. Moreover, the present analysis shows that these inverse electron demand polar cycloadditions present a linear relationship between the activation barriers of the favored ortho regio-isomers and the inverse of electrophilicity differences of the reagents.
A THEORETICAL STUDY OF THE INTERACTIONS OF IODO-PERFLUOROCARBON AND IODO-HYDROCARBON WITH HALOID ANIONS
Authors: WANG YANHUA , ZOU JIANWEI , LU YUNXIANG , YU QINGSEN
Published: December 2006

Ab initio calculations have been performed on a series of complexes formed between iodo-perfluorocarbons(PFCs) and iodo-hydrocarbons(HCs) and haloid anions to gain a deeper insight into the nature of halogen bonds. It appears that halogen bonds in these complexes are much stronger than neutral halogen bonds. Calculations also show that the strength of halogen bonds in iodo-PFC⋯ haloid anion dimers are greater than those in iodo-HC⋯ haloid anion dimers. A comparison of the two complex series reveals that the hybridization state of the carbon atom bonded to iodine has a less pronounced effect on the interatomic distances I⋯X in the iodo-PFC series in relation to the iodo-HC series. PCM calculations used to investigate the solvent effect on halogen bonds unveil that, in the gas phase, fluorine anion prefers to form halogen-bonded complexes with respect to chloride, bromide, and iodine anions; however, the preference is not obvious, and even an opposite order is observed in solutions. It is worth mentioning that the iodo-PFC⋯ fluorine anion complexes present a special structure, i.e. the interatomic I⋯F distances in these complexes are relatively short and the corresponding C–I bonds tend to be further broken. These features, in combination with the geometrical data, indicate that ate-complexes are formed between iodo-PFC and fluorine anions.
MOLECULAR TAILORING APPROACH: TOWARDS PC-BASED AB INITIO TREATMENT OF LARGE MOLECULES
Authors: GADRE SHRIDHAR R. , GANESH V.
Published: December 2006

The development of a fragmentation-based scheme, viz. molecular tailoring approach (MTA) for ab initio computation of one-electron properties and geometry optimization is described. One-electron properties such as the molecular electrostatic potential (MESP), molecular electron density (MED), and dipole moments are computed by synthesizing the density matrix (DM) of the parent molecule from DMs of its small overlapping fragments. The electron density obtained via MTA was found to be typically within 0.5% of its actual counterpart, while maximum errors of about 2% were noticed in the case of the dipole moment and MESP distribution. An attempt is made to develop MTA-based geometry optimization that involves picking relevant energy gradients from fragment self-consistent field (SCF) calculations, bypassing the CPU and memory extensive SCF step of the complete molecule. This is based on the observation that the MTA gradients mimic the actual ones fairly well. As the calculations on individual fragments are mutually independent, this algorithm is amenable to large-scale parallelization and has been extended to a distributed setup of PCs. The code developed is put to test on γ-cyclodextrin, taxol, and a small albumin-binding protein (1prb) for one-electron properties. Further, molecules such as γ-cyclodextrin, taxol, a silicalite, and 1prb are subjected to MTA-based geometry optimization, on a PC cluster. The results indicate a favorable speedup of two to three times over the actual computations in the initial phase of optimization. Furthermore, it enables computations otherwise not possible on a PC. Preliminary results indicate similar savings with sustained accuracy even for large molecules at the level of Møller–Plesset second order perturbation (MP2) theory.
RANDOM PHASE APPROXIMATION FOR ALLOWED AND PARITY NON-CONSERVING ELECTRIC DIPOLE TRANSITION AMPLITUDES AND ITS CONNECTION WITH MANY-BODY PERTURBATION THEORY AND COUPLED-CLUSTER THEORY
Authors: GOPAKUMAR GEETHA , SUR CHIRANJIB , DAS BHANU PRATAP , CHAUDHURI RAJAT K. , MUKHERJEE DEBASHIS , HIRAO KIMIHIKO
Published: December 2006

The connections between the Random Phase Approximation (RPA) and Many-Body Perturbation Theory (MBPT) and its all order generalization, the Coupled-Cluster Theory (CCT), have been explored. Explicit expressions have been derived for the electric dipole amplitudes for allowed and forbidden transitions induced by the parity non-conserving neutral weak interaction. The Goldstone diagrams associated with the RPA terms in both cases are shown to arise in MBPT and CCT, and the numerical verification of this relationship is made for the allowed electric dipole transitions.
RESONANCES IN H+HLi SCATTERING FOR NONZERO TOTAL ANGULAR MOMENTUM (J > 0): A TIME-DEPENDENT WAVE PACKET APPROACH
Authors: PADMANABAN R. , MAHAPATRA S.
Published: December 2006

The resonances in H + HLi scattering for nonzero total angular momentum (J > 0) are examined here by a time-dependent wave packet approach employing an ab initio potential energy surface (PES) [Dunne LJ, Murrell JN, Jemmer P, Chem Phys Lett336: 1, 2001] of the system. The resonances are identified by calculating a set of pseudospectra corresponding to the Franck–Condon transition of a hypothetical initial state to the interaction region of the H + HLi PES. The resonances are characterized by calculating their eigenfunctions and linewidth lifetimes. The resonances for J ≠ 0 are discussed in relation to their counterpart for J = 0. The effect of Coriolis coupling on the resonances obtained from the centrifugal sudden approximation for J = 2 and for K = 0,1,2 is examined.
A THEORETICAL STUDY FOR H2 + CN ↔ HCN + H REACTION AND ITS KINETIC ISOTOPE EFFECTS WITH VARIATIONAL TRANSITION STATE THEORY
Authors: JU LI-PING , HAN KE-LI , ZHANG JOHN Z. H.
Published: December 2006

We present variational transition state theory (VTST) calculations for the H 2 + CN → HCN + H (R1) and D 2 + CN → DCN + D (R2) reactions and their reverses based on a global many-body expansion potential energy surface (PES) for ground-state H 2 CN (ter Horst MA, Schatz GC, Harding LB, J Chem Phys105:558, 1996). It is found that the tunneling effects are negligible over the 200–2000 K temperature range and non-negligible over 100–200 K for R1 and R2 reactions. The C–N bond acts almost as a spectator for both reactions. The present VTST rate constants are in good agreement with the available experimental results and the previous theoretical predictions for R1 and R2 reactions except for the overestimation of rate constants by VTST at lower temperatures that may be caused by recrossing effect. Additionally, the kinetic isotope effects are important for the forward R1 and R2 reactions, but not for the reverses of R1 and R2.
THE PARAMETER-DEPENDENT FERMION STATES FOR MOLECULES WITH SYMPLECTIC SYMMETRY
Authors: SUN C. C. , LI B. F. , LI Z. S. , ZHANG H. X. , HUANG X. R.
Published: December 2006

Under a certain kind of similarity transformation, a parameter-dependent (abbreviated as PD) symplectic group chain Sp(2M) ⊃ Sp(2M - 2) ⊃ ⋯ ⊃ Sp(2) that is characterized by a set of pairing parameters is introduced to build up the PD antisymmetrized fermion states for molecules with symplectic symmetry, and these states will be useful in carrying out the optimization procedure in quantum chemistry. In order to make a complete classification of the states, a generalized branching rule associated with the symplectic group chain is proposed. Further, we are led to the result that the explicit form of the PD antisymmetrized fermion states is obtained in terms of M one-particle operators and M geminal operators.
THEORETICAL STUDY ON THE INTERCONVERSION BETWEEN TWO ISOMERS OF A Ru COMPLEX, CONTAINING A HEMILABILE HYBRID LIGAND
Authors: BI SI-WEI , ZHAO YI , WANG BIN , ZHU XIU-FANG
Published: December 2006

The mechanism on the interconversion between two isomers (1 and 2) of the model complex [ Ru (η5- C 9 H 7){κ3(P, C, C)– PH 2( CH 2 CH = CH 2)}( PH 3)]+ derived from the original one [ Ru (η5- C 9 H 7)κ3(P, C, C)– Ph 2 P ( CH 2 CR = CH 2) ( PPh 3)]+ is theoretically studied by using density functional theory (DFT) calculations at the B3LYP level. It is revealed that the carbon–carbon double bond cannot remain coordinated to the metal center but undergoes flip of the vinyl plane of the hybrid hemilabile ligand, allylphosphine, in the process of interconversion. The results of calculations indicate that isomer 1 is more stable than isomer 2 by 4.63 kcal/mol without considering the solvent effect. The relative stability for the two isomers is rationalized in terms of molecular orbital interaction with symmetry consideration. The bonding character between the carbon–carbon double bond and ruthenium involved in the two isomers is featured by σ-bonding and π-backbonding. Different stabilities of isomers 1 and 2 resulted from their different π-backbonding interactions. The overlap between the antibonding orbital of the carbon–carbon double bond and the symmetry-adapted d orbital of ruthenium in 1 is more efficient than that in 2, leading to the higher stability of isomer 1.
UNDERSTANDING OF MOLECULAR FUNCTIONS: COMPUTATIONAL APPROACHES
Authors: MONDAL CHANDAN KUMAR , LEE JIN YONG
Published: December 2006

Accurate quantum computational chemistry has evolved dramatically. The size of molecular systems, which can be studied accurately using molecular theory, is increasing very rapidly. Theoretical chemistry has opened up a world of new possibilities. It can treat real systems with predictable accuracy. Computational chemistry is becoming an integral part of theoretical and experimental research in chemical science. In this paper, we will review our recent developments in the theoretical and computational study on some very interesting subjects such as fluorescent fluoride sensor, "on–off" molecular switch, electron transport through π-stacking, and molecular electronic device on the basis of the molecular functional levels. We provide a brief introduction about the importance of all these systems in the present scenario of scientific activity and the numerical results and discussion in the light of experimentally found results. We have enjoyed good progress in each of the above areas. We are very excited about our discoveries in each field and would like to share this enthusiasm with readers.
DFT-PCM STUDIES OF THE SOLVENT EFFECTS ON THE ABSORPTION PROPERTIES OF DCM
Authors: WANG BO-CHENG , TAI CHIN-KUEN
Published: December 2006

In this paper, we have performed the optimized structures of the red emitting material, 4-(dicyanomethylene)-2-methyl-6-[p-(dimethyl amino) styryl]-4H-pyran (DCM), with different polarity solvent environments by using the density functional theory (DFT) method, B3LYP/6-31G*. The time-dependent density functional theory (TD-DFT) and the polarizable continuum model (PCM) have been used to obtain the optical properties in the solvent environment. It has been observed that when the solvent polarity increases, the DCM molecule exhibits the red shift in the maximum absorption wavelength [Formula: see text] and enhances the oscillator strength (f). The solvent polarity also enhances the electron transfer ability from the electron-donating dimethylamine group (-N(CH3)2) to the electron-withdrawing =C(CN)2group. The S0→ S1transition of DCM is found to be π–π*. The maximum absorption wavelengths [Formula: see text] of different solvent environments are found to be consistent with the reported experimental results.
LOCALLY PROJECTED MOLECULAR ORBITAL THEORY FOR MOLECULAR INTERACTION WITH A HIGH-SPIN OPEN-SHELL MOLECULE
Authors: IWATA SUEHIRO
Published: December 2006

Locally projected molecular orbital method for molecular interactions is extended to a cluster consisting of a high-spin open-shell molecule and many closed-shell molecules. While deriving the equations, the Hartee–Fock–Roothaan equation without the orthonormal condition is obtained. The stationary conditions for molecular orbitals are expressed in a form of a generalized Brillouin condition. To obtain the molecular orbital coefficient matrix, which satisfies the stationary condition, a single Fock operator form is presented. For the locally projected molecular orbitals for the open-shell cluster, the working matrix representaion is given.
CONFORMATIONAL ANALYSIS OF NEVIRAPINE IN SOLUTIONS BASED ON NMR SPECTROSCOPY AND QUANTUM CHEMICAL CALCULATIONS
Authors: VAILIKHIT V. , BUNSAWANSONG P. , TECHASAKUL S. , HANNONGBUA S.
Published: December 2006

The conformational analysis of HIV-1 Reverse Transcriptase Inhibitor, nevirapine, 11-cyclopropyl-5,-11dihydro-4-methyl-6H-dipyrido[3,2-b2′,3′-e][1,4]diazepin-6-one, was investigated using ab initio and density functional theory calculations. The fully optimized structures and rotational potential energies of the nitrogen and carbon bonds in the cyclopropyl ring (C15-N11-C17-C19, α) were examined in detail. Geometries obtained from all applied calculations show similarities to the complex structure with HIV-1 reverse transcriptase. To obtain more information on the structure, conformational minima of nevirapine, optimized at the B3LYP/6-31G** level, were calculated for the 1H, 13C, and 15N-NMR chemical shifts at the B3LYP/6-311++G** level using the GIAO approach in DMSO and chloroform IEFPCM solvation models. The calculated 1H, 13C-NMR chemical shifts agree well with the experimental data, which indicates that the geometry of nevirapine in solution is similar to that of the molecule in the inhibition complex. Solvation free energies (ΔG sol ) of nevirapine in DMSO and chloroform were also obtained.
ELECTRONIC STRUCTURE AND PHOTOCHEMISTRY OF INORGANIC PHOTOCHROMIC COMPLEX [Cu(N,N′-DIETHYLETHYLENEDIAMINE)2]2+: PLANAR–TETRAHEDRAL GEOMETRY CHANGE ACCOMPANIED WITH d9–d10 ELECTRONIC TRANSITION
Authors: MORI HIROTOSHI , ISHII KAZUMI , MIYOSHI EISAKU
Published: December 2006

A photo-induced geometry isomerization reaction mechanism of a photochromic inorganic complex, [ Cu ( dieten )2]2+ (dieten = N,N ′-diethyletylenediamine), was investigated with density functional molecular orbital theory calculations. A new stable cis-isomer that is assigned to a photo-irradiated (PI) phase was found. In the PI geometry, two N,N ′-diethyl groups are placed more closely than in the most stable low-temperature (LT) phase, and the complex has a slightly twisted structure with steric hindrance. Recently, Takahashi et al. have suggested that two ethyl groups were in trans position in the PI phase from the EXAFS and XANES observation; however, no energy minimum corresponds to such a PI state was found. The photochromic reaction mechanism and electronic structure of [ CuII ( dieten )2]2+ are discussed from a theoretical point of view.
A NEW SCALE OF ELECTRONEGATIVITY OF 54 ELEMENTS OF PERIODIC TABLE BASED ON POLARIZABILITY OF ATOMS
Authors: GHOSH DULAL C. , GUPTA KARTICK
Published: December 2006

A polarizability (α) based new scale of electronegativity (χ) is proposed. The basic algorithm is suggested by exploiting the fact that both polarizability and electronegativity are periodic properties and they are connected by an inverse relationship. Relying upon their express behavior along the periods of the periodic table, a general and straightforward relation between χ and α is suggested as χ = m(1/α)1/3 + c, where m and c are constants. The constants m and c are evaluated by least square fitting by plotting χ vs. (1/α)1/3 for each period separately. Thereafter, the suggested equation is used to evaluate the electronegativity, χ, of 54 elements from H to Xe in terms of least square fitted m and c, and a new set of atomic polarizabilities are computed by Ghosh and Biswas. The evaluated electronegativities exhibit periodicity of groups and periods and reproduce the silicon rule and the expected trend of variation of the electronegativities of d block transition metals. The evaluated electronegativities of the present semiempirical method are quite comparable with those computed by the rigorous mathematical method of Robles and Bartolotti. The efficacy of the new scale is also tested by computing the bond energy of a number of compounds. We have proposed a new formula relating the bond energy with the electronegativity difference. The proposed relation is given by D AB - 〈D AB 〉= 3.8866Δχ + 0.0422, where 〈D AA 〉 = (D AA D BB )1/2, Δχ represents the electronegativity difference, and D AA , D BB , and D AB are the bond energies of homonuclear A–A, B–B, and hetero-nuclear A–B molecules. A comparative study of bond energies evaluated through the proposed relation, determined experimentally, and evaluated through other relations is also furnished. It is demonstrated that the proposed relation of computing the bond energy in terms of Δχ yields good bond energy values. Results demonstrate that the new polarizability based empirical scale of electronegativity is a fairly successful venture.
PARALLEL SUBSPACE ITERATION METHOD FOR THE SPARSE SYMMETRIC EIGENVALUE PROBLEM
Authors: LOMBARDINI RICHARD , POIRIER BILL
Published: December 2006

A new parallel iterative algorithm for the diagonalization of real sparse symmetric matrices is introduced, which uses a modified subspace iteration method. A novel feature is the preprocessing of the matrix prior to iteration, which allows for a natural parallelization resulting in a great speedup and scalability of the method with respect to the number of compute nodes. The method is applied to Hamiltonian matrices of model systems up to six degrees of freedom, represented in a truncated Weyl–Heisenberg wavelet (or "weylet") basis developed by one of the authors (Poirier). It is shown to accurately determine many thousands of eigenvalues for sparse matrices of the order N ≈ 106, though much larger matrices may also be considered.
THE EFFECT OF THE COUPLING BETWEEN VALENCE STATE B2Π AND RYDBERG STATE C2Π ON THE ABSORPTION SPECTRUM OF THE NO MOLECULE
Authors: HAN YONG-CHANG , WANG SEN-MING , YUAN KAI-JUN , CONG SHU-LIN
Published: December 2006

The effect of the coupling between the valence state B 2Π and the Rydberg state C 2Π on the absorption spectrum of the NO molecule is studied by using the quantum wave packet dynamics method. The results show that the coupling between the valence state B 2Π and the Rydberg state C 2Π affects the C 2Π ← X 2Π absorption spectrum both in the intensity and on the location of spectrum peaks. The dynamics of the wave packet of the excited states is also described. One part of the wave packet evolves on the Rydberg state C 2Π and the other is trapped in the valence state B 2Π.
A DFT STUDY ON THE ELECTRONIC CHARACTER OF P700+
Authors: SUN YUMING , DAI ZHENHONG , WANG WEITIAN , SUN YUANPING
Published: December 2006

This density functional study is devoted to the long debated electronic nature of P700+. We found that P700+ is intrinsically a dimer of chlorophyll molecules. The unpaired electron spin distributes equally over two chlorophyll molecule halves in the bare P700+, while the dressed P700+ shows the spin density asymmetry mainly coming from the H-bond donated to 131-keto-O of one half. The experimental contradictions on the electronic nature of P700+ are also discussed.