bluuebunny/crossref_metadata_2025 huggingface dataset:
Bond activation by group-11 transition-metal cations
Authors: de Jong G. Theodoor , Bickelhaupt F. Matthias
Published: July 2009

We have computationally explored C–X bond activation by the group-11 transition-metal cations Cu+, Ag+, and Au+, and, for comparison, Pd, using relativistic density functional theory (DFT) at ZORA-BLYP/TZ2P. Oxidative insertion of the second-row transition-metal species Ag+and Pd leads, for a given bond, to the highest overall reaction barriers. On the other hand, if we compare the different bonds oxidative insertion into the C–F bond is associated with (one of the) highest overall barriers whereas insertion into the C–Cl bond leads to the lowest overall barrier for any transition metal. The main trends in reactivity are rationalized using the activation strain model of chemical reactivity, which is an extension of the fragment approach to reaction profiles. In this model, the shape of the reaction profile ΔE(ζ) and the height of the overall reaction barrier ΔE≠= ΔE(ζ=ζTS) are interpreted in terms of the strain energy ΔEstrain(ζ) associated with deforming the reactants along the reaction coordinate ζ plus the interaction energy ΔEint(ζ) between these deformed reactants: ΔE(ζ) = ΔEstrain(ζ) + ΔEint(ζ).
Pd/X group interchange in the [Pd(Br)(PH3)(C6H5)(C6H5X)] system — Theoretical insights from the isolobal analogy perspective
Authors: Dedieu Alain , Mota Antonio J.
Published: July 2009

DFT-B3LYP calculations have been carried out to assess the fate of the Pd/X group intermolecular exchange in the [PdBr(PH3)(C6H5)(C6H5X)] system, where X is either H, an electropositive atom, or a group such as Li, Na, BH2, AlH2, BeH or BeCH3, and an electronegative atom, or a group such as F, Cl, Br, CH3, OH, and SH. The transfer of H is best viewed as involving the migration of a proton between the two phenyls. At variance with this result, the transfer of the more electropositive entities such as X = Li, Na, BH2, AlH2, BeH, or BeCH3 is not complete. It stops halfway to yield a stable structure in which X can experience interactions with the two phenyl groups that are quite ionic. These stable structures are rationalized through isolobal analogy arguments. In the case of beryllium, the correspondence has been made also with the experimentally known cyclopentadienylberyllium borohydride system, CpBeH4. The results of the DFT geometry optimization call for a re-examination of the gas-phase electron-diffraction structure determination, especially for the bond distances and angles that pertain to the two bridging hydrogens. For the halogen series X = F, Cl, or Br and for the electronegative groups CH3, OH, or SH, the transfer between the two phenyls takes place via a two-step Pd(II)/Pd(IV) oxidative addition/reductive elimination mechanism. The associated energy barriers are nevertheless quite high, except for Br and SH for which the process might be feasible. The dimerization of the PdBr(PH3)(C6H5) system is also analyzed within the isolobal analogy framework.
Glycosidic bond cleavage in deoxynucleotides — A density functional study
Authors: Millen Andrea L. , Wetmore Stacey D.
Published: July 2009

Density functional theory was used to study the glycosidic bond cleavage in deoxynucleotides with the main goal to determine the effects of the nucleobase, hydrogen bonding with the nucleobase, and the (bulk) environment on the reaction energetics. Since direct glycosidic bond cleavage is a high-energy process, two nucleophile models were considered (HCOO–···H2O and HO–), which represent different stages of activation of a water nucleophile. The glycosidic bond cleavage barriers were found to decrease, while the reaction exothermicity increases, with an increase in the nucleobase acidity. The gas-phase barriers and reaction energies for bond cleavage in all deoxynucleotides were found to be significantly affected by hydrogen-bonding interactions with the nucleobase (by up to 30 kJ mol–1 depending on the nucleophile). Although the barriers increase and reaction energies become less exothermic in enzymatic and aqueous environments, the effects of the bulk environment are similar in the presence and absence of small molecules bound to the nucleobase. Therefore, the effects of hydrogen bonding with the bases are approximately the same in all environments. Our results suggest that hydrogen bonding with the nucleobase may play an important role in the glycosidic bond cleavage in both pyrimidine and purine nucleotides in a variety of environments.
An improved neural network method for solving the Schrödinger equation
Authors: Manzhos Sergei , Carrington, Tucker
Published: July 2009

We propose a neural network (NN) based algorithm for calculating vibrational energies and wave functions and apply it to problems in 2-, 4-, and 6-dimensions. By using neurons as basis functions and methods of nonlinear optimization, we are able to compute three states of a 6-D Hamiltonian using only 50 basis functions. In a standard direct product basis, thousands of basis functions would be necessary. Previous NN methods for solving the Schrödinger equation computed one level at a time and optimized all of the parameters using expensive nonlinear optimization methods. Using our approach, linear coefficients in the NN representation of wave functions are determined with methods of linear algebra and many levels are computed at the same time from one set of nonlinear NN parameters. In addition, we use radial basis function neurons to ensure the correct boundary conditions. The use of linear algebra methods makes it possible to treat systems of higher dimensionality.
Organoplatinum(IV) complexes with functional alkyl groups and their use in supramolecular chemistry
Authors: Au Richard H.W. , Findlay-Shirras Lisa J. , Woody Neil M. , Jennings Michael C. , Puddephatt Richard J.
Published: July 2009

The oxidative addition of alkyl bromides RCH2Br (R = C5H4N, C6H4CN, CH2C6H4CO2H, or CH2C6H4CH2CO2H) to dimethylplatinum(II) complexes [PtMe2(LL)] (LL = diimine ligand) gives the corresponding organoplatinum(IV) complexes [PtBrMe2(CH2R)(LL)] containing functionality in the alkyl group RCH2. The pyridyl derivatives can be protonated, while abstraction of the bromide ligand from [PtBrMe2(CH2R)(LL)] can form cationic complexes, which can react with water or form oligomers by self-assembly.
Mechanisms for anionic butadiene polymerization with alkyl lithium species
Authors: Margl Peter
Published: July 2009

Anionic butadiene polymerization by means of [Li-polybutadienyl]x species (x = 1–6, 8) without polar agents was investigated by means of density functional theory (DFT) under conditions relevant to industrial application, namely in a low-dielectric hydrocarbon solvent and at room temperature. The calculations indicate that the dimeric and tetrameric catalyst species together account for the bulk of Li-polybutadienyl species in the polymerization mixture under typical conditions. It is likely that each type of oligomer produces its own “fingerprint” signature polymer microstructure, as there is a systematic variation in the amounts of 1,2- and 1,4-insertions as well as in the preference of cis- and trans-butadiene. According to the calculations, higher aggregated Li species tend to produce more 1,2-insertions and prefer trans- over cis-butadiene insertion, while the dimer prefers trans-butadiene and 1,4-insertions. The dimer closely reproduces the experimentally observed polybutadiene microstructure (5%–10% 1,2-insertion, approximately equal ratios of cis and trans units with a slight predominance of trans). The monomeric catalyst species shows a clear preference for insertion of cis-butadiene over trans-butadiene. Thus, the monomer species is predicted to be present in the polymerization mixture in very small concentrations under normal conditions and the overall polymerization is predicted to be mainly carried out by the dimeric catalyst species.
Chemical bonding and aromaticity in metalloporphyrins,
Authors: Feixas Ferran , Solà Miquel , Swart Marcel
Published: July 2009

We report here the chemical bonding and aromaticity patterns in metalloporphyrins, which were obtained with density functional theory (DFT) calculations at the OPBE/TZP level. This level of theory was previously shown to be very accurate for determining spin-state splittings [J. Chem. Theory Comput. 2008, 4, 2057] of transition-metal complexes. We considered metalloporphyrins along the first-row transition metals (Sc–Zn) extended with alkaline-earth metals (Mg, Ca) and several second-row transition metals (Ru, Pd, Ag, Cd). An energy decomposition analysis was performed to study the metal–ligand interactions, which showed that almost all complexes are significantly stabilized through (covalent) orbital interactions. The only exception is with calcium as the central metal, which interacts with the porphyrin mainly through electrostatic interactions. Furthermore, we studied aromaticity patterns for these complexes by looking at a number of (structural and electronic) aromaticity descriptors, for both the inner-ring and outer-ring of the porphyrin and of the pyrroles. The inner-ring (N16) aromaticity is shown to be unaffected by metal complexation, while the outer-ring (N20) and the pyrrole (N5) aromaticities are found to increase significantly in the metal coordinated porphyrins.
Relativistic hybrid density functional calculations of indirect nuclear spin–spin coupling tensors — Comparison with experiment for diatomic alkali metal halides,
Authors: Bryce David L. , Autschbach Jochen
Published: July 2009

The accurate calculation of the isotropic (Jiso) and anisotropic (ΔJ) parts of indirect nuclear spin–spin coupling tensors is a stringent test for quantum chemistry, particularly for couplings involving heavy isotopes where relativistic effects and relativity – electron correlation cross terms are expected to play an important role. Experimental measurements on diatomic molecules in the gas phase offer ideal data for testing the success of computational approaches, since the data are essentially free from intermolecular effects, and precise coupling anisotropies may be reliably extracted in favourable cases. On the basis of available experimental molecular-beam coupling-tensor parameters for diatomic alkali metal halides, we tabulate known values of Jiso and, taking rotational–vibrational corrections to the direct dipolar coupling constant into account, precise values of ΔJ are determined for the ground rovibrational state. First-principles calculations of the coupling tensors were performed using a recently developed program based on hybrid density functional theory using the two-component relativistic zeroth-order regular approximation (ZORA). Experimental trends in Jiso and ΔJ are reproduced with correlation coefficients of 0.993 and 0.977, respectively. Periodic trends in the coupling constants and their dependence on the product of the atomic numbers of the coupled nuclei are discussed. Finally, the hybrid functional method is also successfully tested against experimental data for a series of polyatomic xenon fluorides and group-17 fluorides.
1H chemical shifts in nonaxial, paramagnetic chromium(III) complexes — Application of novel pNMR shift theory
Authors: Liimatainen Helmi , Pennanen Teemu O. , Vaara Juha
Published: July 2009

We present the first chemical application of the recent, general theory of the nuclear magnetic resonance shielding and chemical shift in paramagnetic compounds, to a set of nonaxial high-spin metallo-organic complexes. The theory is for the first time rigorous for systems of arbitrary spatial and spin symmetry, and introduces new structure to the isotropic, anisotropic but symmetric, and anisotropic and antisymmetric parts of the shielding tensor. We apply the theory using density functional calculations of the proton chemical shift in a family of nonaxial chromium(III) complexes possessing a quartet ground electronic spin state. We discuss the various contributions to the isotropic chemical shift, and compare the full theory to approximate forms appropriate to the doublet case on the one hand, and to the doublet case at the nonrelativistic limit, on the other hand. The performance of various exchange-correlation functionals in reproducing the recently measured experimental chemical shifts is evaluated.
Hetero-Diels–Alder reactions involving Fe(CO)3-coordinated dienal and formyltrimethylenemethane catalyzed by Lewis acids — A theoretical study
Authors: Acosta-Silva Carles , González-Blanco Òscar , Branchadell Vicenç
Published: July 2009

The hetero-Diels–Alder reactions of butadiene with Fe(CO)3-coordinated formylbutadiene and formyltrimethylenemethane catalyzed by Lewis acids have been theoretically studied through density functional calculations. The results obtained show that, for the reaction with (formylbutadiene)Fe(CO)3, the kinetically most favourable product is the one corresponding to the attack of butadiene on the s-cis conformer of the formylbutadiene fragment when the reaction is catalyzed by BF3, and the one corresponding to the attack on the s-trans conformer when the catalyst is TiCl4. On the other hand, for the reaction with (formyltrimethylenemethane)Fe(CO)3 catalyzed by BF3, the product corresponding to the attack on the s-trans conformer is predicted to be favoured. These results have been interpreted through an energy decomposition analysis of the potential-energy barriers.
Spin–orbit ab initio investigation of the UV photoinduced bond cleavage in iodotrimethylstannane
Authors: Ben Amor N. , Daniel C.
Published: July 2009

The photoinduced homolytic cleavage of the Sn–I bond in iodotrimethylstannane (CH3)3SnI, observed after UV irradiation, is investigated by means of spin–orbit ab initio calculations based on CASSCF (complete active space self-consistent field) and MS-CASPT2 (multi-state complete active space 2nd order perturbation theory) methods. The absorption electronic spectrum is characterized by ten low-lying 1,3A′ and 1,3A″ spin eigenstates corresponding to py(I),px(I) → σ*SnI; σSnI → σ*SnI and py(Sn), px(Sn) → σ*SnI, where σSnI and σ*SnI are the bonding and anti-bonding orbitals of the Sn–I bond along the pz axis. From the 1A′ electronic ground state and these ten spin eigenstates, 21 spin–orbit states are generated leading to various deactivation channels of (CH3)3SnI, corresponding to the formation of radicals (CH3)3Sn• and •I and to the ionic species (CH3)3Sn+ and I–. Irradiation into the upper band at 175 nm should lead to the heterolytic cleavage of the Sn–I bond to form the ionic primary products exclusively, whereas absorption into the shoulder at 250 nm induces the homolytic breaking with formation of the radical products.
Binding of polar monomers in the complexes with organometallic ethylene polymerization catalysts — Natural orbitals for chemical valence and energy decomposition analysis
Authors: Srebro Monika , Mitoraj Mariusz , Michalak Artur
Published: July 2009

The binding mode of polar monomers in complexes with late-transition-metal catalysts for ethylene polymerization was studied by density functional theory (DFT) calculations. The Ziegler–Rauk energy decomposition scheme was used to characterize the geometry distortion and steric and orbital-interaction terms in the bonding energy, while Natural Orbitals for Chemical Valence (NOCV) were applied to describe the donation and back-bonding components of the bond between the monomer and the catalyst. The NOCV analysis allowed for comparison of the donor–acceptor properties of different monomers in the σ- and π-complexes. The complexes with the model, cationic Ni– or Pd–diimine catalysts, N^N–Ni(H)+ and N^N–Pd(H)+, and the neutral Ni–anilinotropone system, N^O–Ni(H), were investigated. The monomers studied included: simple olefins (Et and Pr); examples of oxygen- and nitrogen-containing polar monomers (methyl acrylate (MA), vinyl acetate (VAc), their fluorinated derivatives (FMA, FVAc), vinyl ether (VE), acrylonitrile (AN), and β-butenoic nitrile (BN); vinyl and allyl amines (VAm, PrAm); and a tertiary dimethyl vinyl amine (MVAm). The results demonstrate that the metal-based fragment has a significant influence on the relative stability of the σ- and π-complexes; the π-binding mode increases in the following order: N^N–Ni(H)+ < N^N–Pd(H)+ < N^O–Ni(H). The results of the Ziegler–Rauk bond-energy decomposition indicate that for some monomers (MA, FMA, VAc, AN, VAm, MVAm) the preference of the coordination mode has a steric (electrostatic and Pauli) origin. For other monomers (VE, FVAc, BN, PrAm) the changes in the orbital-interaction terms are important as well. The results of the NOCV analysis indicate that for both, σ- and π-coordination modes there exist components describing σ-donation and π-back-bonding. The sequences of σ-donor and π-acceptor properties of monomers in the π-complexes as well as σ-complexes are similar for the considered catalysts.
Ab initio electronic structure and direct dynamics simulations of CH3OCl
Authors: Wong Stephanie Y. Y. , Roy Pierre-Nicholas , Brown Alex
Published: July 2009

The ground (X1A′) and two lowest lying excited singlet states (11A″ and 21A′) of methyl hypochlorite have been examined using ab initio electronic structure techniques to validate computationally efficient methods, upon which direct dynamics can be based, versus high-level ones, for which direct dynamics would be intractable. Ground-state equilibrium geometries and vibrational frequencies determined using density functional theory (DFT) with the 6-31G(d) basis set are tested against coupled-cluster theory (CCSD(T)) results from the literature. Vertical excitation energies and transition dipole moments calculated at the complete active space self-consistent field CASSCF/6-31+G(d) level of theory are benchmarked against multireference configuration interaction (MRCI) results with the aug-cc-pVXZ (X = D, T, Q) family of basis sets. The excited-state gradients that will govern the classical dynamics are compared for CASSCF/6-31+G(d) versus MRCI/aug-cc-pVXZ (X = D, T). To carry out the ab initio molecular dynamics (AIMD), existing electronic structure codes have been interfaced with the molecular modelling toolkit (MMTK), an open-source program library for molecular simulation applications. We use two examples to demonstrate the use of direct dynamics in MMTK: a canonical ground-state trajectory to sample positions and momenta, and an excited-state microcanonical trajectory based on CASSCF. The work presented here forms the basis for future study of the photodissociation of CH3OCl. As well, the implementation of AIMD within MMTK provides a useful tool for examining a variety of other research problems.
A solid-state 31P NMR study of 1:1 silver–triphenylphosphine complexes — Interpretation of 1J(107,109Ag,31P) values,
Authors: Chen Fu , Oh Se-Woung , Wasylishen Roderick E.
Published: July 2009

High-resolution solid-state 31P NMR spectroscopy was used to investigate a series of 1:1 silver–triphenylphosphine complexes, [Ph3PAgX]n, where X is a monovalent anion and n = 1, 2, 3, 4, or ∞. The 31P CP MAS NMR spectra reveal the number of distinct phosphorus sites in these complexes as well as the |1J(109Ag,31P)| values, which range from 401 ± 10 Hz (X = N3–) to 869 ± 10 Hz (X = SO3CF3–). The data obtained here and in earlier investigations indicate that |1J(109Ag,31P)| values for silver–tertiary phosphine complexes decrease as Ag–P bond lengths increase. This experimental conclusion is supported by DFT calculations, which also indicate that the Fermi-contact mechanism is the only important spin–spin coupling mechanism for 1J(109Ag,31P) in these complexes. In addition, the crystal structure of a silver–triphenylphosphine trifluoroacetate tetramer was determined using X-ray crystallography, and the structure of a silver–triphenylphosphine chloride tetramer was reinvestigated.
Contrasting total carbon stocks between ecological site series in a subboreal spruce research forest in central British Columbia
Authors: Bois Claudette H. , Janzen Darren T. , Sanborn Paul T. , Fredeen Arthur L.
Published: July 2009

A study was conducted to determine if consideration of ecological site classification in combination with stand age would describe total ecosystem carbon (C) better than consideration of just stand age alone. The research was conducted in the 9250 ha University of Northern British Columbia/The University of British Columbia Aleza Lake Research Forest in central British Columbia. Over three field seasons (2003–2005), 38, 72, and 27 plots were established in mesic, subhygric, and hygric stands, respectively, with stand ages ranging from 5 to 350+ years. Mineral soil C stocks were significantly influenced by moisture regime, where hygric > subhygric > mesic (93, 77, and 65 t C·ha–1, respectively). Mineral soil and forest floor C stocks were not related to stand age, indicating their resilience to partial-cut and clear-cut forest harvesting systems historically implemented throughout the study area. Subhygric stands had the highest total ecosystem C stocks in the Aleza Lake Research Forest, having approximately 18% more C than mesic and hygric stands, principally due to higher mineral soil C stocks (than mesic stands) and improved C sequestration in large trees (over hygric stands). Consideration of ecological site classification in addition to stand age information improved total ecosystem C stock estimates over the use of stand age alone.
Diameter of lodgepole pine and mortality caused by the mountain pine beetle: factors that influence their relationship and applicability for susceptibility rating
Authors: Björklund Niklas , Lindgren B. Staffan
Published: July 2009

During outbreaks the mountain pine beetle ( Dendroctonus ponderosae Hopkins) kills large lodgepole pine trees ( Pinus contorta Dougl. ex Loud.) more frequently than smaller ones. There is, however, considerable variation in the relation of diameter to incidence of attack. In a meta-analysis of published data we found that the relationship was primarily determined by geographic location (elevation, latitude, and longitude). We propose a new tree mortality measure, the probability of death index, defined as the average percentage of mortality for trees >23 cm. The index may improve the precision in predictive modeling of tree mortality, as it provides a biologically relevant measure of mortality, since it only includes trees that contribute to the growth of an epidemic and is not influenced by the number of trees within a diameter class. To be useful to forest managers, it must be possible to predict the index from stand parameters that are easily measured. The usefulness of the index was supported by a meta-analysis, which showed that 53% of the variation in the mortality index was explained by geographic location. Tree density did not explain any additional variation. Future research is needed to evaluate the performance of the probability of death index compared with that of other mortality measures.
Sequestration of carbon in the humus layer of Swedish forests — direct measurements
Authors: Berg Björn , Johansson Maj-Britt , Nilsson Åke , Gundersen Per , Norell Lennart
Published: July 2009

To determine sequestration rates of carbon dioxide (CO2) we calculated the carbon (C) storage rate in humus layers of Swedish forests with Podsolic soils, which account for 14.2 × 106ha of the 22.7 × 106ha of forested land in Sweden. Our data set covered 41 years of humus inventories and mean humus layer thickness in 82 513 plots. We analysed three forest types: (i) all combinations of tree species, (ii) forests dominated (>70%) by Norway spruce ( Picea abies (L.) Karst.), and (iii) forests dominated (>70%) by Scots pine ( Pinus sylvestris L.). To relate changes in humus layer thickness to land area we used the intersections in 25 km × 25 km grids and used kriging interpolation, permitting calculations for each forest type. For each intersection mean humus thickness for each year was calculated and regressed against time to obtain the rate of change. This rate, humus bulk density, and humus C concentration were used to calculate sequestration rates. The mean sequestration rate was 251 kg C·ha–1·year–1, which is higher than theoretical values. The sequestration rate was positively related to temperature sum, albeit including effects of forest management. The pine-dominated forest type had a mean rate of 283 kg C·ha–1·year–1, and the spruce-dominated had a mean rate of 239 kg C·ha–1·year–1. Under similar site conditions, pine sequestered more C than spruce (difference of 71 kg C·ha–1·year–1; p < 0.0001), showing the importance of this type of ecosystem for C sequestration.
Spatial variability of stand-scale residuals in Ontario’s boreal forest fires
Authors: Perera Ajith H. , Dalziel Benjamin D. , Buse Lisa J. , Routledge Robert G.
Published: July 2009

Knowledge of postfire residuals in boreal forest landscapes is increasingly important for ecological applications and forest management. While many studies provide useful insight, knowledge of stand-scale postfire residual occurrence and variability remains fragmented and untested as formal hypotheses. We examined the spatial variability of stand-scale postfire residuals in boreal forests and tested hypotheses of their spatial associations. Based on the literature, we hypothesized that preburn forest cover characteristics, site conditions, proximity to water and fire edge, and local fire intensity influence the spatial variability of postfire residuals. To test these hypotheses, we studied live-tree and snag residuals in 11 boreal Ontario forest fires, using 660 sample points based on high resolution photography (1:408) captured immediately after the fires. The abundance of residuals varied considerably within and among these fires, precluding attempts to generalize estimates. Based on a linear mixed-effects model, our data did not support the hypotheses that preburn forest cover characteristics, site conditions, and proximity to water significantly affect the spatial variability of stand-scale residuals. The results do indicate, however, that stand-scale residual variability is associated with local fire intensity (strongly) and distance to fire edge (weakly).
An economic perspective on the determination of dumping in the US–Canada softwood lumber trade — an analysis for Ontario
Authors: Yang Feng'e , Kant Shashi , Asinas Emmanuel
Published: July 2009

Dumping has been one of the most controversial issues in the never-ending softwood lumber trade dispute between the United States (US) and Canada. In this paper, we investigate whether the softwood lumber producers in Ontario dumped product into their major market in the US during the period from April 1996 to September 2006. The Enhanced Parity Bounds Model was used to explore the possibility that Ontario’s softwood lumber producers had exercised price discrimination between the Toronto market and the Great Lakes market. Our analysis indicates that the industry had on average charged a higher price in the Great Lakes market than in the Toronto market during this period. Based on this evidence and the economic conditions in which a US antidumping investigation and two administrative reviews were conducted, we draw the conclusion that the Ontario’s softwood lumber producers did not dump product into the US market during the study period.
Soil compaction associated with cut-to-length and whole-tree harvesting of a coniferous forest
Authors: Han Sang-Kyun , Han Han-Sup , Page-Dumroese Deborah S. , Johnson Leonard R.
Published: July 2009

The degree and extent of soil compaction, which may reduce productivity of forest soils, is believed to vary by the type of harvesting system, and a field-based study was conducted to compare soil compaction from cut-to-length (CTL) and whole-tree (WT) harvesting operations. The CTL harvesting system used less area to transport logs to the landings than did the WT harvesting system (19%–20% vs. 24%–25%). At high soil moisture levels (25%–30%), both CTL and WT harvestings caused a significant increase of soil resistance to penetration (SRP) and bulk density (BD) in the track compared with the undisturbed area (p < 0.05). In the center of trails, however, only WT harvesting resulted in a significant increase of SRP and BD compared with the undisturbed area (p < 0.05). Slash covered 69% of the forwarding trail area in the CTL harvesting units; 37% was covered by heavy slash (40 kg·m–2) while 32% was covered by light slash (7.3 kg·m–2). Heavy slash was more effective in reducing soil compaction in the CTL units (p < 0.05). Prediction models were developed that can be used to estimate percent increases in SRP and BD over undisturbed areas for both CTL and WT harvesting systems.
EXACT SOLUTIONS OF THE DIRAC EQUATION WITH HARMONIC OSCILLATOR POTENTIAL INCLUDING A COULOMB-LIKE TENSOR POTENTIAL
Authors: AKCAY H. , TEZCAN C.
Published: July 2009

In this work, we study the Dirac equation with scalar, vector, and tensor interactions. The Dirac Hamiltonian contains quadratic scalar and vector potentials, as well as a tensor potential. The tensor potential is taken as a sum of a linear term and a Coulomb-like term. It is shown that the tensor potential preserves the form of the harmonic oscillator potential and generates spin-orbit terms. The energy eigenvalues and the corresponding eigenfunctions are obtained for different alternatives.
ASYMMETRIC EXCLUSION PROCESSES ON LATTICES WITH A JUNCTION: THE EFFECT OF UNEQUAL INJECTION RATES
Authors: WANG XIONG , JIANG RUI , NISHINARI KATSUHIRO , HU MAO-BIN , WU QING-SONG
Published: July 2009

Asymmetric exclusion processes (ASEP) on lattices with a junction, in which two or more parallel lattice branches combine into a single one, is important as a model for complex transport phenomena. This paper investigates the effect of unequal injection rates in ASEP with a junction. It is a generalization of the work of Pronina and Kolomeisky [J. Stat. Mech. P07010 (2005)], in which only equal injection rates are considered. It is shown that the unequal rates give rise to new phases and the phase diagram structure is qualitatively changed. The phase diagram and the density profiles are investigated by using Monte Carlo simulations, mean field approximation and domain wall approach. The analytical results are in good agreement with Monte Carlo simulations.
EFFECT OF NUT PARAMETER ON THE ANALYTIC EXTENSION OF THE CAUCHY HORIZON THAT DEVELOP IN COLLIDING WAVE SPACE–TIMES
Authors: GURTUG OZAY , HALILSOY MUSTAFA
Published: July 2009

The Cauchy horizon forming colliding wave solution due to Chandrasekhar and Xanthopoulos (CX) has been generalized by inclusion of the NUT (Newman–Unti–Tamburino) parameter. This is done by transforming the part of the inner horizon region of a Kerr–Newman–NUT black hole into the space of colliding waves. By taking appropriate combination of Killing vectors and analytically extending beyond the Cauchy horizon the timelike hyperbolic singularities are resolved as well. This provides another example of its kind among the type-D metrics with special emphasis on the role of the NUT parameter. Finally, it is shown that horizons of colliding higher-dimensional plane waves obtained from the black p-branes undergoes a similar procedure of analytic extension.
Chapter 9 Meson Spectroscopy
Authors: Bian Jian-Ming , Bytev Vladimir , Chen Ying , Jin Hong-Ying , Jin Shan , Qin Hu , Shen Xiao-Yan , Wu Ning , Xu Guo-Fa , Zhang Zhen-Xia , Zhao Qiang , Zhemchugov Alexey , Zheng Han-Qing , Zhu Shi-Lin , Zou Bing-Song
Published: July 2009

The following sections are included:

Introduction

Conventional Meson Spectrum

Glueball Spectrum

Hybrid Mesons

Multiquarks

Molecular States
Chapter 15 Charmonium Transitions
Authors: Kuang Yu-Ping , Barnes Ted , Yuan Changzheng , Chen Haixuan
Published: July 2009

The following sections are included:

Hadronic Transitions

Radiative Transition

Channels for Measurement at BES-III

Monte Carlo Simulation of Spin-Singlet Charmonium States
Chapter 17 Radiative Decays
Authors: Garcia i Tormo Xavier , Soto Joan , Yuan Changzheng
Published: July 2009

The following sections are included:

Inclusive Radiative Decays

Exclusive Radiative Decays
Chapter 20 Miscellaneous
Authors: Li Junli , Qiao Cong-Feng , Mo Xiaohu , Ping Ronggang , Yuan Changzheng
Published: July 2009

The following sections are included:

Bell Inequalities in High Energy Physics

Special Topics in [Formula: see text] Final States
Chapter 21 Charm Production and D Tagging
Authors: He Kang-Lin , Sun Sheng-Sen , Yang Ming , Zhang Da-Yong
Published: July 2009

The following sections are included:

Charmed Particle Production Cross Sections

D-Meson Tagging
Chapter 22 Leptonic, Semileptonic D(DS) Decays and CKM Matrix Elements
Authors: Yang Ya-Dong , Li Hai-Bo , Zou Jia-Heng , Chen Jiang-Chuan , Liu Jian , Rong Gang , Yang Mao-Zhi , Liu Hui-Hui , Ma Hai-Long , Charles J. , Descotes-Genon S. , Lacker H. , Li H. B. , Roos L. , T'Jampens S. , Xing Z. Z.
Published: July 2009

The following sections are included:

Leptonic Decays

Semileptonic Decays

Impact on CKM Measurements
Chapter 27 Rare and Forbidden Charm Decays
Authors: Li Hai-Bo , Yang Ya-Dong
Published: July 2009

The following sections are included:

Introduction

Rare Charm Decays in the SM

New Physics Analysis

Summary
Chapter 28 Tau Physics Near Threshold
Authors: Stahl Achim
Published: July 2009

The following sections are included:

Introduction

Tau Production at Threshold

Physics Opportunities

Running Strategy
Chapter 30 τ Mass Near Threshold
Authors: Mo Xiao-Hu , Wang Y. K. , Yuan C. Z. , Fu C. D.
Published: July 2009

The following sections are included:

Introduction

Statistical Optimization

Systematic Uncertainty

Energy Measurement at BES-III

Summary
Charm Physics
Authors: Asner D. M. , Bigi I. I. , Charles J. , Chen J. C. , Cheng H. Y. , Descotes-Genon S. , He K. L. , Li H. B. , Liu J. , Liu H. H. , Ma H. L. , Rong G. , Roos L. , Sun S. S. , T'Jampens S. , Wu Y. L. , Xing Z. Z. , Yang M. , Yang M. Z. , Yang Y. D. , Zhang D. Y. , Zhong M. , Zou Jia-Heng
Published: July 2009

Nobody doubts that the discovery of hadrons with charm of the hidden and open variety – i.e. charmonium as well as D mesons – was instrumental in the acceptance of the Standard Model (SM) in general, and of quarks as physical degrees of freedom, rather than objects of mere mathematical convenience, in particular. Yet charm is all too often viewed as a quantum number with a great past and with no particularly interesting future. This is due to SM predictions of a rather dull electroweak phenomenology of CKM parameters, a low frequency for [Formula: see text] oscillations, tiny (at best) CP asymmetries, and extremely rare flavor changing neutral currents which, in any case, are swamped by huge backgrounds from long-distance dynamics…
THE FRACTIONAL CALCULUS OF VARIATIONS FROM EXTENDED ERDÉLYI-KOBER OPERATOR
Authors: EL-NABULSI AHMAD RAMI
Published: July 2009

Fractional calculus of variations (FCV) has recently attracted considerable attention as it is deeply related to the fractional quantization procedure. In this work, the FCV from extended Erdélyi-Kober fractional integral is constructed. Our main goal is to exhibit a general treatment for dissipative systems, in particular the harmonic oscillator (HO) that has time-dependent mass and time-dependent frequency. The general linear equation of damped Erdélyi-Kober harmonic oscillator is constructed from which a time-dependent mass generalized law was derived exhibiting different types of behavior. This relatively new time-dependent mass law permits us to point out several possible cases simultaneously in contrast to many models discussed in the literature and without making use of any types of fractional derivatives. Some results on Hamiltonian part, namely Hamilton equations for the damped HO were obtained and discussed in detail.
PRESSURE-RELATED PHASE STABILITY OF MgSiO3and(Mg0.75, Fe0.25)SiO3 AT LOWER MANTLE CONDITION
Authors: DENG LI-WEI , ZHAO JI-JUN , LIU HONG , WU DI , GONG ZI-ZHENG
Published: July 2009

Relative stability of different phases for MgSiO 3 and ( Mg 0.75, Fe 0.25) SiO 3 within 0–110 GPa are investigated using first-principles method. For MgSiO 3, the computed equation of state for orthorhombic phase of Pbnm space group agrees well with experimental results. The relative stability reduces from observed Pbnm orthorhombic phase to intermediated tetragonal P4mbm phase, and then to hypothetical cubic [Formula: see text] phase. For ( Mg 0.75, Fe 0.25) SiO 3, the same sequence of relative phase stability is observed. Thus, the low-symmetric orthorhombic MgSiO 3 should be favored in the lower mantle condition, while adding Fe into MgSiO 3 will make it less stable at the same depth.
DISCRETE CHOICES UNDER SOCIAL INFLUENCE: GENERIC PROPERTIES
Authors: GORDON MIRTA B. , NADAL JEAN-PIERRE , PHAN DENIS , SEMESHENKO VIKTORIYA
Published: July 2009

We consider a model of socially interacting individuals that make a binary choice in a context of positive additive endogenous externalities. It encompasses as particular cases several models from the sociology and economics literature. We extend previous results to the case of a general distribution of idiosyncratic preferences, called here Idiosyncratic Willingnesses to Pay (IWP). When j, the ratio of the social influence strength to the standard deviation of the IWP distribution, is small enough, the inverse demand is a classical monotonic (decreasing) function of the adoption rate. However, even if the IWP distribution is mono-modal, there is a critical value of j above which the inverse demand is non-monotonic. Thus, depending on the price, there are either one or several equilibria.

Beyond this first result, we exhibit the generic properties of the boundaries limiting the regions where the system presents different types of equilibria (unique or multiple). These properties are shown to depend only on qualitative features of the IWP distribution: modality (number of maxima), smoothness and type of support (compact or infinite). The main results are summarized as phase diagrams in the space of the model parameters, on which the regions of multiple equilibria are precisely delimited. We also discuss the links between the model and the random field Ising model studied in the physics literature.
A LARGE DEFORMATION, VISCOELASTIC, THIN ROD MODEL: DERIVATION AND ANALYSIS
Authors: BEYROUTHY J. , LE DRET H.
Published: July 2009

We present a Cosserat-based three-dimensional to one-dimensional reduction in the case of a thin rod, of the viscoelastic finite strain model introduced by Neff. This model is a coupled minimization/evolution problem. We prove the existence and uniqueness of the solution of the reduced minimization problem. We also show a few regularity results for this solution which allow us to establish the well-posedness of the evolution problem. Finally, the reduced model preserves observer invariance.
INDIA IN THE WORLD OF NUCLEAR PHYSICS: THEN AND NOW
Authors: MITRA A. N.
Published: July 2009

A panoramic view is offered of the principal ideas underlying the phenomenal growth of Nuclear Physics from the Thirties to Now, extending to the subhadronic and to high temperature QGP physics. In this narrative, Indian efforts are highlighted where possible, within a common international standard.
NUCLEON RESONANCES AND QUARK STRUCTURE
Authors: LONDERGAN J. T.
Published: July 2009

A review of the past 50 years of study of resonances, leading to our understanding of the quark content of baryons and mesons. The quark structure of the proton as revealed through deep inelastic scattering. Structure functions and what they reveal about proton structure. Prospects for further studies with new and upgraded facilities, particularly a proposed electron-ion collider.
NUCLEON IN NUCLEAR MEDIUM
Authors: PHATAK SHASHIKANT C.
Published: July 2009

The behavior of a nucleon in nuclear medium is discussed in Chiral Color Dielectric Model. It is assumed that the nucleons in nuclear medium produces a background dielectric field and the quark and dielectric field equations are solved self consistantly in presence of the dielectric field. A nucleon in nuclear medium is then constructed by means of standard procedure followed in chiral bag models. The corrections due to center of mass motion, color magnetic interaction and meson interaction are included. The calculations show that the nucleon becomes bigger in the medium but its mass does not change much. It is found that beyond a certian density, bound solutions in which quarks are bound in self-generated dielectric field are not possible. Thus, the calculations indicate that there is a critical density beyond which the matter consists of deconfined quarks.
THE NN AND NY INTERACTIONS AT SMALL ENERGIES–NEWS FROM AN OLD FIELD
Authors: MACHNER HARTMUT , SIUDAK REGINA
Published: July 2009

We discuss recent results and open problems in baryon-baryon interactions at small relative energies. The method of final state interactions is revisited. Perspectives at new facilities are discussed shortly.
DECAYS OF η AND η' MESONS–AN INTRODUCTION
Authors: KUPSC ANDRZEJ
Published: July 2009

Decays of η and η' mesons are a laboratory for low energy strong interactions. The rate of isospin breaking decays into three pions constrain ratios of the light quark masses. Particle distributions from hadronic decays allow to study the elementary processes of the low energy Quantum Chromodynamics: π - π and π - η interactions. Radiative and conversion decays of the η and η' mesons provide information about internal structure of the mesons and the decay mechanism is strongly influenced by vector meson resonances.

The lecture gives an introduction to the common decays of η and η' mesons. The main theme of the lecture are three body decays: hadronic decays, radiative decays into π+π-γ, π0γγ and Dalitz decays into ℓ+ℓ-γ.
OPEN AND HIDDEN STRANGENESS PRODUCTION IN NUCLEON-NUCLEON COLLISIONS
Authors: SHYAM RADHEY
Published: July 2009

Strange meson production reactions are expected to provide information on the manifestation of quantum chromodynamics in the non-perturbative regime of energies larger than that of the low energy pion physics. The K meson contains a strange quark (s) or antiquark [Formula: see text] while the η meson has hidden strangeness as it contains some component of the [Formula: see text] pair. In this lecture we present an overview of describing the production of K and η mesons in nucleon-nucleon collisions within an effective Lagrangian model (ELM) where meson production proceeds via excitation, propagation and subsequent decay of intermediate baryonic resonant states. Specific examples are discussed where proper understanding of the data is still lacking.
Compacting cuts
Authors: Carr Robert D. , Konjevod Goran , Little Greg , Natarajan Venkatesh , Parekh Ojas
Published: July 2009

For a graph (
V
,
E
), existing compact linear formulations for the minimum cut problem require Θ(|
V
||
E
|) variables and constraints and can be interpreted as a composition of |
V
| − 1 polyhedra for minimum
s
-
t
cuts in much the same way as early approaches to finding globally minimum cuts relied on |
V
| − 1 calls to a minimum
s
-
t
cut algorithm. We present the first formulation to beat this bound, one that uses
O
(|
V
|
2
) variables and
O
(|
V
|
3
) constraints. An immediate consequence of our result is a compact linear relaxation with
O
(|
V
|
2
) constraints and
O
(|
V
|
3
) variables for enforcing global connectivity constraints. This relaxation is as strong as standard cut-based relaxations and has applications in solving traveling salesman problems by integer programming as well as finding approximate solutions for survivable network design problems using Jain's iterative rounding method. Another application is a polynomial-time verifiable certificate of size
n
for for the NP-complete problem of
l
1
-embeddability of a rational metric on an
n
-set (as opposed to a certificate of size
n
2
known previously).
Minimizing movement
Authors: Demaine Erik D. , Hajiaghayi Mohammadtaghi , Mahini Hamid , Sayedi-Roshkhar Amin S. , Oveisgharan Shayan , Zadimoghaddam Morteza
Published: July 2009

We give approximation algorithms and inapproximability results for a class of movement problems. In general, these problems involve planning the coordinated motion of a large collection of objects (representing anything from a robot swarm or firefighter team to map labels or network messages) to achieve a global property of the network while minimizing the maximum or average movement. In particular, we consider the goals of achieving connectivity (undirected and directed), achieving connectivity between a given pair of vertices, achieving independence (a dispersion problem), and achieving a perfect matching (with applications to multicasting). This general family of movement problems encompasses an intriguing range of graph and geometric algorithms, with several real-world applications and a surprising range of approximability. In some cases, we obtain tight approximation and inapproximability results using direct techniques (without use of PCP), assuming just that P ≠ NP.
Near-optimal algorithms for maximum constraint satisfaction problems
Authors: Charikar Moses , Makarychev Konstantin , Makarychev Yury
Published: July 2009

In this article, we present two approximation algorithms for the maximum constraint satisfaction problem with
k
variables in each constraint (MAX
k
-CSP).

Given a (1 − ε) satisfiable 2CSP our first algorithm finds an assignment of variables satisfying a 1 −
O
(√ε) fraction of all constraints. The best previously known result, due to Zwick, was 1 −
O
(ε
1/3
).

The second algorithm finds a
ck
/2

k

approximation for the MAX
k
-CSP problem (where
c
> 0.44 is an absolute constant). This result improves the previously best known algorithm by Hast, which had an approximation guarantee of Ω(
k
/(2

k

log
k
)).

Both results are optimal assuming the unique games conjecture and are based on rounding natural semidefinite programming relaxations. We also believe that our algorithms and their analysis are simpler than those previously known.
Instability of FIFO in the permanent sessions model at arbitrarily small network loads
Authors: Andrews Matthew
Published: July 2009

We show that for any
r
> 0, there is a network of First-In-First-Out servers and a fixed set of sessions such that:

—The network load is
r
with respect to the permanent sessions model with bounded arrivals.

—The network can be made unstable.
Complex open-system design by quasi-agents
Authors: Bastani Behzad , Greaves David
Published: July 2009

Drastically increasing involvement of Computer Science in different aspects of human life and sciences and the reciprocal dependency these sciences have developed on Computer Science and technology have deployed extremely challenging grounds for software architecture and design as a discipline. The requirements related to the management of complexity which is in the essence of these new domains combined with sizes which are orders of magnitude larger than the conventional business applications necessitate development of new paradigms. Since we are in fact beyond the age of writing one program by one group which takes care of one type of issue for one class of users, the new paradigms should guarantee some type of technical pluralism which allows indefinite number of people addressing indefinite aspects of complex clusters of issues in an ongoing effort over indefinite amount of time. The technical basis should provide for easy and ideally automated integration of all such efforts. This means the capability of random program design and integration based on a supporting and unifying conceptual framework. In contributing to these principles, Nuclear-Process Oriented Analysis and Modeling (NPOAM) [3] presented the capability of random modeling and design while establishing itself on the supporting framework of Abstraction-oriented Frames [4]. In an ongoing research to further modularize and streamline this methodology, this paper presents the idea and method of application of NPOAM to agent-base systems. The accomplishment of this goal is substantiated through a double implementation effort, one in an agent simulation environment and the other through the use of industrial strength modeling and application development tools.

This paper also extends the agent-oriented framework to propose a new concept named "quasi-agents" which is essentially related to mostly deterministic environments and offers examples of quasi-agents in implementation.