bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of metal complexation on ring opening of bowl‐shaped hydrocarbons: Theoretical study
Authors: Jemmis Eluvathingal D. , Parameswaran Pattiyil , Anoop Anakuthil
Published: October 2003

Density functional theory study on benzenoid and tris‐acetylenic structure of fullerene and its fragments shows that tris‐acetylenic model structures lead to benzenoid model structure due to the proximity of π‐orbitals in the former. The tris‐acetylenic model structures are stabilized on metal complexation in comparison to the parent benzene–acetylene equilibrium. In going from Cr to Co, the acetylenic metal complex becomes more stabilized than the benzene–metal complex. The curved surface of the tris‐acetylenic fullerene fragments causes one set of π‐orbital of the tris‐acetylenic groups to rehybridize so as to bend more toward the metal fragments than found in the parent acetylene complexes. This leads to the increased overlap between metal fragments and tris‐acetylenic model structures. We also studied the benzenoid and tris‐acetylenic model complexes of C12H6 and C12H12 where five‐membered rings are replaced with more strained four‐membered rings. © 2003 Wiley Periodicals, Inc. Int J Quantum Chem, 2003
Potential energy barriers for dissociative attachment to HF.HF and HCl.HCl: Ab initio study
Authors: Rauk A. , Armstrong D. A.
Published: October 2003

Dissociative attachment (DA) of an electron to the dimers of HF and HCl, reaction (1)

equation image

has been investigated by theoretical calculations at MP2 and CCSD(T) levels with large basis sets. Transition structures (TSs) for the loss of an H atom and formation of the FHF− and ClHCl− anions were located by analytic methods. Initial electron attachment to HF.HF dimer occurs without activation and yields a dipole‐bound anion state (DBS) as shown previously. Reaction (1) is endothermic by 65.8 kJ/mol at the CCSD(T)/aug‐cc‐pVDZ level. An intermediate ion‐induced dipole complex between H · and FHF− is reached from the DBS over a potential barrier of 66.6 kJ/mol. Analysis of the charge distribution as a function of the distance to the departing H · reveals that the diffuse DBS collapses to a much more compact valence configuration prior to the TS being reached. In the valence configuration, the electron occupies the σ* orbital of the terminal HF bond. DA to HCl.HCl differs from the fluorine case in several important respects. HCl.HCl does not form a DBS. Rather, electron attachment occurs by direct insertion into the σ* orbital of the terminal HCl bond with an activation energy of 20.3 kJ/mol. As in the fluorine case, electron capture occurs before the TS. The electron density collapses to a valence configuration when the HCl bond is stretched to about 1.45 Å, intermediate between that in the neutral dimer, 1.28 Å, and in the TS to DA, 1.57 Å. A “T‐shaped” ion‐induced dipole complex, bound by about 2 kJ/mol, lies between the TS and the separated H atom and ClHCl− anion products. With respect to DA, the chlorine system is intermediate between the fluorine system and the previously reported bromine system. The latter was found to undergo DA with a 0.0‐kJ/mol barrier. © 2003 Wiley Periodicals, Inc. Int J Quantum Chem, 2003
Localized orbital interactions: d‐electron exchange and correlation
Authors: Whitten J. L.
Published: October 2003

Several approaches to treating electron correlation and exchange in localized d‐orbital distributions are discussed. The approaches are designed to treat large systems such as transition metal clusters or solid surfaces by simpler approaches than configuration interaction calculations on the entire system. The analysis is based on the concept of an electronic subspace, defined by localized orbitals, embedded in a larger electronic system. An expression is developed for d‐electron correlation contributions that is equivalent to an external potential. This potential can be used in conjunction with single‐determinant or configuration interaction wave functions. The concept of using potentials instead of orbital basis functions to treat exchange in delocalized electronic systems is discussed. © 2003 Wiley Periodicals, Inc. Int J Quantum Chem, 2003
Nonlocal potentials in independent‐electron models
Authors: Nesbet R. K.
Published: October 2003

This article summarizes the motivation for extending current density functional theory to include nonlocal one‐electron potentials and proposes methodology for practical calculations. The theoretical model, orbital functional theory, has been shown to be exact in principle for the general N‐electron problem but must depend in practice on a parameterized correlation energy functional. The discussion here is intended to honor Lee Allen and bring up to date some conversations that we began in 1954. © 2003 Wiley Periodicals, Inc. Int J Quantum Chem, 2003
Molecular integrals and information processing
Authors: Barnett Michael P.
Published: October 2003

We report new applications of computer algebra (CA) to the evaluation of molecular integrals over STOs. Closed formulas were tabulated for all the overlap integrals with principal quantum numbers 1 to 12. These provide unrestricted precision results that are compared with earlier numerical work of other authors. All the auxiliary functions needed to compute two‐ and three‐center integrals have been reduced to closed form. We describe novel features of the software infra‐structure that have wider application in theoretical chemistry and computational science. © 2003 Wiley Periodicals, Inc. Int J Quantum Chem, 2003
Rotational barriers of methyl fluorosulfonate and chlorosulfonate: Comparison between computational methods and experiment
Authors: Schmiedekamp Ann , Schmiedekamp Mendel , Nair K. P. R.
Published: October 2003

Molecular structures derived from microwave and electron diffraction experiments on methyl fluorosulfonate and methyl chlorosulfonate were ambiguous as to whether gauche or anti conformations were most stable. Rotational barriers are computed at the SVWN/6‐31G**, BP86/6‐31G**, B3LYP/6‐31G**, and localized MP2/ 6‐31G** levels. Calculations are in agreement that the gauche conformation is a minimum. The syn and anti rotational barriers relative to the gauche minimum are determined and found to be attractive dominant. Optimized geometry differences among the different methods are examined. © 2003 Wiley Periodicals, Inc. Int J Quantum Chem, 2003
Equilibrium structures for the cis and trans isomers of 1,2‐difluoroethylene and the cis,trans isomer of 1,4‐difluorobutadiene
Authors: Craig Norman C. , Groner Peter , McKean Donald C. , Tubergen Michael J.
Published: October 2003

Microwave spectra for seven isotopomers of cis‐1,2‐difluoroethylene have been reinvestigated and extended with the pulsed‐molecular‐beam Fourier transform method. Rotational Hamiltonians that include a full set of quartic centrifugal distortion constants have been fit for each isotopomer. Ground‐state rotational constants for the trans isomer were available from an investigation of the high‐resolution infrared spectra of several isotopomers. Equilibrium rotational constants have been extracted for the cis and trans isomers from the experimental ground‐state constants and the vibration–rotation constants computed at the MP2/6‐31G(d) level. Equilibrium structures have been fit to the equilibrium principal moments of inertia for both isomers, and isomeric differences in the bond lengths and bond angles have been interpreted in terms of the strong influence of fluorine substitution. For cis,trans‐1,4‐difluorobutadiene a similar derivation of the equilibrium structure has been achieved through the combination of published microwave data and quantum chemical calculations. This substance provides an opportunity to examine the influence of cis and trans fluorine substitution within a single molecule. Evidence is weighed for the adequacy of vibration–rotation constants computed with the MP2/6‐31G(d) model. © 2003 Wiley Periodicals, Inc. Int J Quantum Chem, 2003
Sufficient condition for monotonic electron density decay in many‐electron systems
Authors: Ayers Paul W. , Parr Robert G.
Published: October 2003

For one‐electron systems, if the external potential increases monotonically from the nucleus the ground‐state electron density is monotonic. For two‐electron densities, similar results hold for the Kohn–Sham potential. Similarly, for many‐electron systems monotonicity of the sum of the Kohn–Sham potentials and “Pauli potential” (from the correction to the Weisacker kinetic energy) is sufficient for monotonic decay of the electron density. © 2003 Wiley Periodicals, Inc. Int J Quantum Chem, 2003
Regularities in the bond dissociation enthalpies of molecules of types AB and BAB: Energetics of 10‐ and 16‐valence electron ions of groups 13, 15, and 16
Authors: Deakyne Carol A. , Li Le , Zheng Wencui , Xu Danyu , Liebman Joel F.
Published: October 2003

For the quantitative and qualitative understanding of molecular energetics, contemporary calorimetric and mass spectrometric measurement techniques and correspondingly high‐level quantum chemical calculational methodologies increasingly work in concert. For example, letting A and B be group 14 and 16 elements, respectively, for their 10‐valence electron AB and 16‐valence electron AB2 gas‐phase diatomic and triatomic species, the bond enthalpy ratio 〈D(AB2)〉/D(AB) has been shown to remarkably constant, namely, 0.77 ± 0.02. In the current study we discuss the corresponding bond enthalpy ratio for the valence isoelectronic cations and anions, e.g., for the carcinogen [NO]+, explosive precursor [NO2]+, and discrete (monomeric, i.e., nonsalt containing) anions [BO2]− and [AlO2]−. From a combination of results taken from archival literature measurements and new quantum chemical calculations reported in this article, again roughly constant ratios are found. Numerically, these ratios are 0.66 ± 0.03 and 0.86 ± 0.02 for cations and anions, respectively. That the ratios increase in the order cation < neutral < anion is also explained in our study. © 2003 Wiley Periodicals, Inc. Int J Quantum Chem, 2003
Ab initio molecular dynamics with maximally localized Wannier functions
Authors: Sharma Manu , Wu Yudong , Car Roberto
Published: October 2003

We present a novel formulation of ab initio molecular dynamics that should be useful to simulate insulating systems. In this scheme maximally localized Wannier functions instead of delocalized Bloch states evolve on the fly during nuclear dynamics. Localized Wannier orbitals offer several advantages over orbitals that are delocalized in the entire simulation cell. In fact, at variance with the latter, they provide a picture of the electronic bonds consistent with simple chemical intuition. In addition, by taking advantage of their exponential localization it should be possible to develop ab initio molecular dynamics schemes having a computational cost that scales linearly rather than cubically with system size. We show that maximally localized Wannier functions can be calculated efficiently within Car–Parrinello dynamics and use water in gas and liquid phase as a test system to demonstrate our scheme and illustrate its usefulness. © 2003 Wiley Periodicals, Inc. Int J Quantum Chem, 2003
Molecular structures, thermochemistry, and electron affinities for the dichlorine oxides: Cl2On/Cl2O (n = 1–4)
Authors: Li Qianshu , Lü Shunfeng , Xie Yaoming , Schleyer Paul V. R. , Schaefer Henry F.
Published: October 2003

The molecular structures, relative energies, vibrational frequencies, and electron affinities for the Cl2On/Cl2O (n = 1–4) systems have been investigated using hybrid Hartree–Fock/density functional theories (BHLYP and B3LYP) and pure density functional theories (BP86 and BLYP). The three different types of neutral/anion energy differences reported in this research are the adiabatic electron affinity (EAad), the vertical electron affinity (EAvret), and the vertical detachment energy (VDE). The basis set used in this work is of double‐ζ plus polarization quality with additional s‐ and p‐type diffuse functions, and it is denoted DZP++. The geometries are fully optimized by all four DFT methods. We have predicted a number of possible low‐lying local minima, including some that are unprecedented. Most strikingly, in several cases structures that have been observed in the laboratory turn out not to be lowest in energy for a particular chemical composition. Two structures are predicted with a formally seven‐coordinate chlorine atom. The global minima for the Cl2On/Cl2O (n = 1–4) systems are ClOCl (C2v), ClClO− (Cs), ClOOCl (C2), OOCl (C2v), ClOOOCl (C2/C1), ClO(O2)Cl− (Cs), trans‐ClO(O2)OCl (Ci), and trans‐ClO(O2)OCl− (Ci), respectively. The relative energies of the different minima are reported. Five of the 42 structures predicted here have been determined experimentally. Our theoretical geometries and vibrational frequencies are carefully compared with the limited available experimental results, and the BHLYP functional in general provides the best agreement. The ClClO− and ClClO ground states might be regarded as Cl− … ClO and Cl− … ClO2 complexes, respectively. The adiabatic electron affinities, obtained at the favored DZP++ BLYP level of theory, are 3.12 eV for Cl2O, 3.96 eV for Cl2O2, 3.66 eV for Cl2O3, and 4.15 eV for Cl2O4. The adiabatic EAs for the first three systems are similar to those of Br2On (3.14, 3.80, and 3.46 eV with BLYP for Br2On, n = 1–3), and this may reflect the geometric similarity between these bromine and chlorine species. But, EAad for Br2O4 (1.97 eV) is different from Cl2O4 because the neutral and anionic bromine species have different global minimum geometries from those for Cl2O4. © 2003 Wiley Periodicals, Inc. Int J Quantum Chem, 2003
Determination of the crystalline structure of nonlinear molecules in a combined quantum chemical and classic lattice potential description
Authors: Ko Gwon Hee , Fink William H.
Published: October 2003

The general problem of the prediction of the crystal parameters and molecular structure of nonlinear molecules is taken up in a treatment that couples the molecular electronic structure determination to the surrounding crystalline lattice field. The molecular electronic structure method used may be at any level of sophistication, but we used the Hartree–Fock approximation in this application. A partial charge analysis of the molecular electronic structure is performed to establish the values of atom‐centered partial charges that interact via Coulomb's law, along with a Lennard–Jones potential between all atoms to establish a crystalline lattice field. The Lennard–Jones parameters are taken from the widely used AMBER force field. The lattice field terms are included in the molecular Hamiltonian and exert forces on the nuclei, leading to a somewhat different equilibrium structure than is obtained for the isolated molecule. The positions, orientations, and unit cell parameters are optimized for the lattice field, leading to a full determination of the crystal structure, including the space group. Results for sulfur dioxide, ammonia, and water are reported. In each case an equilibrium crystalline geometry faithfully reproducing the experimentally determined space group is obtained. © 2003 Wiley Periodicals, Inc. Int J Quantum Chem, 2003
From electrons to proteins and back again
Authors: Lesk Arthur M.
Published: October 2003

The study of protein structure is now a legitimate topic in physics as well as in biochemistry. General methods for comparing and classifying the topologies of protein folding patterns are useful in organizing the structures that are known and enumerating possible protein structural patterns that have not yet been observed. A tableau representation of protein structures, suitable for manipulation and searching by algorithms, is described and an application to searching the databanks of known structures for a set of combinations of substructures is reported. © 2003 Wiley Periodicals, Inc. Int J Quantum Chem, 2003
Critical distance model for the energy of activation of the Bergman cyclization of enediynes
Authors: Gaffney Shannon M. , Capitani Joseph F. , Castaldo Lyana , Mitra Abhijit
Published: October 2003

The reaction profile of the Bergman cyclization of enediynes is written as a cubic polynomial expansion about the critical distance. Using the “simple sewing” approximation, a relationship is derived that expresses the energy of activation as a function of the critical distance, with the effect of other geometric and electronic factors accounted for in the expansion coefficients. A training set of 10 representative enediynes were selected and input parameters were calculated by density functional theory at the B3LYP/6‐311G* level of theory. All calculations were corrected for zero‐point energy. All singlet biradical calculations were also checked for wave function stability. Calibration curves were then constructed that correlate the activation energy of cyclization of the molecules in the test set with the critical distance parameter. © 2003 Wiley Periodicals, Inc. Int J Quantum Chem, 2003
Ab initio MO study of the symmetrical and asymmetrical isomers of bridging alkynylaluminum and alkynylberyllium dimers
Authors: Seida Pamela R. , Bundens Jeanne W. , Francl Michelle M.
Published: October 2003

The structures of models for known alkynylaluminum‐ and alkynylberyllium‐bridged dimers were predicted using ab initio molecular orbital methods at the HF/6‐31G* level. In both cases, the preferred structure has the bridging alkynyl fragments tilted toward one metal center. Structural comparisons and fragment molecular orbital arguments were used to elucidate the electronic factors leading to the distortion. The essential bonding interaction that stabilizes these structures is π complexation of the alkynyl fragment to one of the metal centers. © 2003 Wiley Periodicals, Inc. Int J Quantum Chem, 2003
Origin of the bathochromic shift in the early photointermediates of the rhodopsin visual cycle: A CASSCF/CASPT2 study
Authors: Schreiber Marko , Buss Volker
Published: October 2003

CASSCF/CASPT2 calculations have been applied to study the excited‐state properties of the chromophore in rhodopsin and in the early photointermediate, photorhodopsin. For rhodopsin, the chromophore geometry was taken from an optimized X‐ray structure while for photorhodopsin the structure proposed by Bifone et al.J Phys Chem B 1997, 101, 2954 was employed. The experimentally observed bathochromic shift of 72 nm is faithfully reproduced by the calculation. Analysis of a model chromophore in which the transition between the geometries is performed stepwise reveals that this shift is predominantly caused by double bond torsion. © 2003 Wiley Periodicals, Inc. Int J Quantum Chem, 2003
First‐principles simulation of the UV absorption spectrum of ketene
Authors: Nooijen Marcel
Published: October 2003

The absorption spectrum of ketene (CH2CO) in the 145‐ to 220‐nm region is calculated completely from first principles and compared to a recent high‐resolution synchrotron radiation experiment J Chem Phys 2002, 117, 4306. The simulations are based on a vibronic model, which is extracted from routinely applicable coupled cluster calculations for electronically excited states. Nonadiabatic effects are assessed by a comparison of the vibronic model simulations with Franck–Condon calculations and are found to be important to understand various aspects of the absorption spectrum of ketene. © 2003 Wiley Periodicals, Inc. Int J Quantum Chem, 2003
Synthesis, structure, and physical properties of a new phenalenyl‐based neutral radical crystal: Correlation between structure and transport properties in carbon‐based molecular conductors
Authors: Chi X. , Itkis M. E. , Tham F. S. , Oakley R. T. , Cordes A. W. , Haddon R. C.
Published: October 2003

A new class of phenalenyl‐based neutral radical molecular conductors has recently been reported; a distinctive feature of these molecular solids is the absence of the well‐defined conducting pathway(s) that are characteristic of the organic charge‐transfer salts. These radicals do not stack in the solid state, and the requisite carbon–carbon contacts are all larger than the sum of the van der Waals distances. Magnetic susceptibility measurements show that these compounds usually exist as isolated free radicals with one spin per molecule (at least over some temperature range), apparently supporting the idea that there is little interaction between the molecules in the solid state. Nevertheless, these radicals show the highest conductivity (σRT = 0.05 S/cm) of any neutral organic solid and the conduction mechanism is at present unresolved. In this article we report a structurally related radical with a resistivity five orders of magnitude higher than that of the previously reported radicals. We analyze the crystallographic and electronic structure of this solid in detail and point out some of the challenges that remain in relating structure, magnetism, and conductivity in this new class of organic solids. © 2003 Wiley Periodicals, Inc. Int J Quantum Chem, 2003
Dopamine responsiveness to drugs of abuse: A shell‐core investigation in the nucleus accumbens of the mouse
Authors: Zocchi Alessandro , Girlanda Elena , Varnier Giorgia , Sartori Ilaria , Zanetti Lara , Wildish Grant A. , Lennon Mark , Mugnaini Manolo , Heidbreder Christian A.
Published: October 2003

The existence of subterritories within the nucleus accumbens has now been widely supported by histochemical, neurochemical, electrophysiological, as well as morphological and ultrastructural studies and suggest specific afferent and efferent systems involved in different behavioral aspects. Microdialysis studies in the rat have consistently shown that most drugs of abuse increase extracellular dopamine levels preferentially in the shell subregion of the nucleus accumbens. The study of the relative roles of NAc subregions may considerably help our understanding of the neurobiological basis of drug addiction. Accordingly, the aim of the present work was to extend the outcome of rat studies to the mouse species. Five major drugs of abuse were systemically and acutely administered to mice with a microdialysis probe implanted in either the shell or the core. A statistical comparison was performed on data transformed as percentage values of baseline dopamine vs. logarithmic values with baseline dopamine as a covariate. Results show a significant increase in dopamine levels in both the shell and core subregions following cocaine, amphetamine, nicotine, ethanol, and morphine treatments. A difference between shell and core after cocaine, nicotine, and morphine was evident when data were analyzed as percent values of baseline. However, such a shell‐core dichotomy became no longer significant when ANOVA was applied on the statistically more appropriate logarithmic transformation of data with baseline as a covariate. The significant baseline differences among groups of mice (dopamine levels in the shell significantly lower compared with dopamine levels in the core) may have compromised, at least in part, the statistical procedure usually applied in microdialysis studies. These findings suggest that a careful evaluation of the data is required when subtle changes in extracellular levels of DA are measured. Synapse 50:293–302, 2003. © 2003 Wiley‐Liss, Inc.
Amygdaloid D1 receptors are not linked to stimulation of adenylate cyclase
Authors: Leonard Sarah K. , Anderson Carl M. , Lachowicz Jean E. , Schulz David W. , Kilts Clinton D. , Mailman Richard B.
Published: October 2003

In contrast to the classic signal transduction of D1 dopamine receptors in striatum or molecular expression systems, it has been reported that D1 receptor agonists do not stimulate adenylate cyclase in homogenates of microdissected nuclei of the amygdaloid complex. This article examines this phenomenon in detail to determine if lack of cAMP signaling in the amygdaloid complex is an experimental artifact, or an indication of a marked difference from the well‐studied basal ganglia terminal fields. Thus, whereas dopamine agonists failed to increase cAMP synthesis in the amygdala, forskolin, guanine nucleotides, or Mg2+ were able to stimulate adenylate cyclase activity in the same preparations. Under several different conditions, caudate preparations responded more robustly than amygdaloid preparations, while amygdala homogenates exhibited higher basal production of cAMP. Whereas the β‐adrenergic agonist isoproterenol was able to stimulate cAMP efflux in membranes from both the caudate and amygdala under a variety of tested conditions, neither dopamine nor fenoldopam (D1 agonist) could stimulate adenylate cyclase in the amygdala. Additionally, while manipulation of Ca2+ and calmodulin affected the differential actions of dopamine in the caudate, no change in these parameters restored sensitivity to dopamine in the amygdala. Together, these data challenge the commonly accepted notion that cAMP is a mandatory signaling pathway for D1 receptors. Because it is now proven that G protein‐coupled receptors can signal promiscuously, elucidation of the non‐cAMP‐dependent signaling mechanisms resulting from D1 activation is clearly critical in understanding how this important receptor functions in situ. Synapse 50:320–333, 2003. © 2003 Wiley‐Liss, Inc.
Direct activation by dopamine of recombinant human 5‐HT1A receptors: Comparison with human 5‐HT2C and 5‐HT3 receptors
Authors: Oz Murat , Zhang Li , Rotondo Alessandro , Sun Hui , Morales Marisela
Published: October 2003

The effects of dopamine (DA) on the function of human 5‐HT1A receptors expressed in Xenopus oocytes and CHO‐K1 cells were investigated. In addition, the effect of DA on the activation of three different types of human 5‐HT receptors (5‐HT1A, 5‐HT2C, and 5‐HT3) were studied comparatively in Xenopus oocyte expression system. Application of 5‐HT or DA in oocytes coexpressing 5‐HT1A receptors and G‐protein‐activated inwardly rectifying potassium channels (GIRK1) induced inward currents with respective EC50 values of 4.2 nM and 11.2 μM. Maximal responses induced by DA were 85 ± 4% of maximal 5‐HT currents and DA responses were blocked by the specific 5‐HT1A antagonist, WAY‐100635 (50 nM). In CHO‐K1 cells expressing 5‐HT1A receptors, 5‐HT and DA inhibited the specific binding of selective antagonist [3H]‐8‐OH‐DPAT with IC50 values of 10.2 nM and 1.4 μM, and both 5‐HT and DA inhibited the forskolin‐induced accumulation of cAMP. In oocytes expressing 5‐HT2C receptors, 5‐HT and DA induced inward currents with respective EC50 values of 6.2 nM and 67.7 μM. Magnitudes of maximal DA induced currents were 42 ± 3% of maximal 5‐HT responses and blocked by the 5‐HT2 antagonist, piperazine (1 μM). In oocytes expressing 5‐HT3 receptors, 5‐HT and DA induced fast inward currents with respective EC50 values of 2.1 μM and 266.3 μM. Maximal DA induced currents were 37 ± 3% of maximal 5‐HT responses and blocked the specific 5‐HT3 antagonist LY‐278584 (0.1 μM). Comparison of the potencies and efficacies of 5‐HT and DA indicated that the relative potency of DA increased in the order of 5‐HT3 > 5‐HT1A > 5‐HT2C, and relative efficacy increased in the order of 5‐HT1A > 5‐HT2C > 5‐HT3. These results suggest that although DA activates different subtypes of human 5‐HT receptors directly, the potency and efficacy of the binding site varies significantly among different receptors. Synapse 50:303–313, 2003. Published 2003 Wiley‐Liss, Inc.
Evaluation of a new norepinephrine transporter PET ligand in baboons, both in brain and peripheral organs
Authors: Ding Yu‐Shin , Lin Kuo‐Shyan , Garza Victor , Carter Pauline , Alexoff David , Logan Jean , Shea Colleen , Xu Youwen , King Payton
Published: October 2003

Reboxetine is a specific norepinephrine transporter (NET) inhibitor and has been marketed in several countries as a racemic mixture of the (R,R) and (S,S) enantiomers for the treatment of depression. Its methyl analog (methylreboxetine, MRB) has been shown to be more potent than reboxetine itself. We developed a nine‐step synthetic procedure to prepare the normethyl precursor, which was used to synthesize [11C]O‐methylreboxetine ([11C]MRB). We also developed a convenient resolution method using a chiral HPLC column to resolve the racemic precursor to obtain enantiomerically pure individual precursors that lead to the individual enantiomers (R,R)‐[11C]MRB and (S,S)‐[11C]MRB. Here we report an evaluation of the racemate and individual enantiomers of [11C]MRB as radioligands for PET imaging studies of NET systems in baboons both in brain and in peripheral organs. The relative regional distribution of the radioactivity after injection of [11C]MRB in baboon brain is consistent with the known distribution of NET. For a NET‐poor region such as striatum, there were no significant changes in the striatal uptakes with and without the nisoxetine pretreatment. In contrast, a significant blocking effect was observed in NET‐rich regions such as thalamus and cerebellum after injection of racemic [11C]MRB, with an even more dramatic effect after injection of (S,S)‐[11C]MRB. These results, along with the fact that there was no regional specificity and no blocking effect by nisoxetine for (R,R)‐[11C]MRB, suggest the enantioselectivity of MRB in vivo, consistent with previous in vitro and in vivo studies in rodents. PET studies of baboon torso revealed a blocking effect by desipramine only in the heart, a NET‐rich organ, after injection of (S,S)‐[11C]MRB, but not the (R,R)‐isomer. These studies demonstrate that the use of (S,S)‐[11C]MRB would allow a better understanding of the role that NET plays in living systems. Synapse 50:345–352, 2003. © 2003 Wiley‐Liss, Inc.
The neglected firm
Authors: Heptonstall John
Published: October 2003

Jorge Vasconcellos e Sà. 2002. The Neglected Firm. Hampshire, UK: Palgrave Macmillan.
154 pages; ISBN 0‐333‐98712‐8.
Discontinuous Galerkin methods
Authors: Cockburn B.
Published: October 2003

This paper is a short essay on discontinuous Galerkin methods intended for a very wide audience. We present the discontinuous Galerkin methods and describe and discuss their main features. Since the methods use completely discontinuous approximations, they produce mass matrices that are block‐diagonal. This renders the methods highly parallelizable when applied to hyperbolic problems. Another consequence of the use of discontinuous approximations is that these methods can easily handle irregular meshes with hanging nodes and approximations that have polynomials of different degrees in different elements. They are thus ideal for use with adaptive algorithms. Moreover, the methods are locally conservative (a property highly valued by the computational fluid dynamics community) and, in spite of providing discontinuous approximations, stable, and high‐order accurate. Even more, when applied to non‐linear hyperbolic problems, the discontinuous Galerkin methods are able to capture highly complex solutions presenting discontinuities with high resolution. In this paper, we concentrate on the exposition of the ideas behind the devising of these methods as well as on the mechanisms that allow them to perform so well in such a variety of problems.
Genetic diversity analysis of captive populations: The Vietnamese sika deer (Cervus nippon pseudaxis) in zoological parks
Authors: Thévenon Sophie , Bonnet Amélie , Claro Françoise , Maillard Jean‐Charles
Published: October 2003

The Vietnamese sika deer (Cervus nippon pseudaxis) is an endangered subspecies; it has disappeared in the wild, but is being bred in zoological parks. We studied the neutral genetic diversity and population structure of herds kept in different European zoos, using nine microsatellite loci. The goal was to evaluate the consequences of founding effects and breeding practices on the level and structure of genetic variability. The level of genetic diversity within the European zoos is not lower than that of the populations kept in Vietnamese farms. Strong differences among zoological parks and between the European group and the Vietnamese population were detected. This is probably due to founding effects, genetic drift, and possibly hybridization in both Europe and Vietnam. We expected to find a much lower level of genetic diversity in Europe. The current overall level of genetic diversity is probably due to the recent introduction of Cuc Phuong individuals, and to important differences among the populations of different zoological parks, which increase the total genetic variability. Although the current level of genetic variability is not particularly low, future levels are probably threatened by the current herd sizes and structure. Based on these results, management guidelines are proposed. Zoo Biol 22:465–475, 2003. © 2003 Wiley‐Liss, Inc.
Splitting suckling data of bottlenose dolphin (Tursiops truncatus) neonates in human care into suckling bouts
Authors: Jacobsen Troels B. , Mayntz Michael , Amundin Mats
Published: October 2003

This study presents a first approach to determine a suckling bout criterion interval (BCI) by applying a loge frequency analysis to a dataset of Tursiops truncatus neonate feeding frequencies. The data were gathered by continuous observation on four calves 15–24 hr a day for the first 14 days postpartum. The study was conducted at the dolphinarium of the Kolmården Wild Animal Park, Kolmården, Sweden. Based on a total of 3,752 individual suckling intervals, a BCI of 107.7 sec was established. The relevance of this finding is discussed. Zoo Biol 22:477–488, 2003. © 2003 Wiley‐Liss, Inc.
Seasonal variations in gastrointestinal tract fill of grazing Zebu cattle in the Sahel
Authors: SCHLECHT E. , SANGARÉ M. , BECKER K.
Published: October 2003

The gastrointestinal tract (gut) contents of male Zebu cattle (Bos indicus) were studied in the southern Sahelian zone of Mali. Measurements were carried out on 39 animals in mid-dry season (MDS) and 15 at the end of the dry season (late dry season, LDS).

After overnight fasting, the animals were weighed and then slaughtered. The different gut compartments were emptied and representative samples of their fill were analysed for contents of dry matter (all) and NDF (reticulo-rumen only).

Related to fasted live weight (FLW), gut fresh matter (FM) fill (g FM/kg FLW) increased from 165·7±4·81 g in MDS to 227·5±3·05 g in LDS (P[les ]0·001), liquid gut contents (g fluid/kg FLW) increased from 138·9±4·65 to 193·5±2·49 g (P[les ]0·001) and gut dry matter fill (g DM/kg FLW) increased from 26·8±0·88 to 34·0±0·97 g (P[les ]0·001). Fresh matter content of the reticulo-rumen accounted for 77% and 80% of the entire gut FM fill in MDS and LDS, respectively. While the NDF component in reticulo-rumen fill (g NDF/kg DM) increased from 778·5±5·63 g in MDS to 836·6±6·37 g in LDS (P[les ]0·001), the ratio between dry matter and fluid in the reticulo-rumen (g DM/g fluid) decreased from 193·2±10·17 g in MDS to 169·0±5·54 g in LDS (P[les ]0·05).

The data support the notion that African breeds of Zebu cattle adjust to deteriorating feeding conditions by increasing reticulo-rumen dry matter and fluid contents. In-depth studies are needed to quantify the physiological benefits resulting from this strategy.
Effect of three environments on the efficiency of indirect selection in Eragrostis curvula (lovegrass) genotypes
Authors: DI RENZO M. A. , IBAÑEZ M. A. , BONAMICO N. C. , FARICELLI M. E. , POVERENE M. M. , ECHENIQUE C. V.
Published: October 2003

A significant genotype–environment interaction can limit gains in selecting superior genotypes since the best genotype in one locality may not be the best one in another locality. The efficiency of indirect selection is related to the heritability of the trait and to the genetic correlation between localities. Since a major objective of Eragrostis curvula (lovegrass) breeding programmes in Argentina is to select superior genotypes from new cultivar introductions, research on the relative effectiveness of direct and indirect selection is necessary in order to identify localities under which the efficiency of indirect selection could be maximized. To do this, experiments using a set of 18 hybrids were carried out in three localities from the semi-arid region of Argentina. Aerial biomass yield, leaf length, crown diameter, panicle number and panicle length were measured and an analysis of variance and covariance were performed. The high genetic correlation obtained suggests that the genetic mechanisms involved in the expression of these traits would be the same, or at least very similar, in Río Cuarto, Villa Mercedes and Bahía Blanca environments where the hybrids showed a stable performance. In general, the heritability obtained was higher in Villa Mercedes and Bahía Blanca than in Río Cuarto. For a given selection intensity the expected correlated response in Villa Mercedes and Bahía Blanca to indirect selection was compared with the expected gain with direct response to selection in Río Cuarto. For dry matter yield, indirect selection in Bahía Blanca did not differ from selection done in Río Cuarto (−3%). However, for performance in Villa Mercedes indirect selection was shown to be less efficient (−29%). For the other traits considered, indirect selection was variable and less efficient, ranging from −18 to −34%. The estimated decrease in efficiency of selection for all the traits considered in the locality of Río Cuarto was higher than in the other localities, suggesting that this place was not a good choice for carrying out indirect selection. Conversely, genetic progress would be faster if selection was carried out in Villa Mercedes, because the evaluations provide higher and more accurate estimates of the heritabilities than in the other localities.
The effects of triazole and strobilurin fungicide programmes on nitrogen uptake, partitioning, remobilization and grain N accumulation in winter wheat cultivars
Authors: RUSKE R. E. , GOODING M. J. , JONES S. A.
Published: October 2003

Field experiments were conducted over 3 years to assess the effect of a triazole fungicide programme, and additions of strobilurin fungicides to it, on nitrogen uptake, accumulation and partitioning in a range of winter wheat cultivars. Commensurate with delayed senescence, fungicide programmes, particularly when including strobilurins, improved grain yield through improvements in both crop biomass and harvest index, although the relationship with green area duration of the flag leaf (GFLAD) depended on year and in some cases, cultivar. In all years fungicide treatments significantly increased the amount of nitrogen in the above-ground biomass, the amount of nitrogen in the grain and the nitrogen harvest index. All these effects could be linearly related to the fungicide effect on GFLAD. These relationships occasionally interacted with cultivar but there was no evidence that fungicide mode of action affected the relationship between GFLAD and yield of nitrogen in the grain. Fungicide treatments significantly reduced the amount of soil mineral N at harvest and when severe disease had been controlled, the net remobilization of N from the vegetation to the grain after anthesis. Fungicide maintained the filling of grain with both dry matter and nitrogen. The proportionate accumulation of nitrogen in the grain was later than that of dry matter and this difference was greater when fungicide had been applied. Effects of fungicide on grain protein concentration and its relationship with GFLAD were inconsistent over year and cultivar. There were several instances where grain protein concentration was unaffected despite large (1·5 t/ha) increases in grain yield following fungicide use. Dilution of grain protein concentration following fungicide use, when it did occur, was small compared with what would be predicted by adoption of other yield increasing techniques such as the selection of high yielding cultivars (based on currently available cultivars) or by growing wheat in favourable climates.
Variation in morphological traits in Phaseolus vulgaris L. from northern Spain
Authors: FLORES F. , SÁNCHEZ-TREJOS P. , CUBERO J. I. , GIL J.
Published: October 2003

A collection of 112 accessions of common beans from the north of Spain has been evaluated for 24 characters during 2 years. A combination of cluster plus canonical discriminant analysis using morphological traits to generate canonical functions was able to separate landraces from different geographic areas of northern Spain, assigning them to germplasm groups related to their centres of origin. The accessions were clustered in three groups in both years. Two groups were related to races with South American origins (races ‘Chile’, ‘Peru’ and ‘Nueva Granada’), the other group was related to races with Mesoamerican origins (races ‘Mesoamerica’ and ‘Durango’). The variation found was higher in the west of the geographic area studied decreasing toward the east. These results will permit a more efficient management and conservation of these resources, and their efficient use in breeding programmes.
Proceedings of the Thirty-fifth Meeting of the Agricultural Research Modellers' Group
Authors: FRANCE J. , CROMPTON L. A.
Published: October 2003

This group, which is concerned with the applications of mathematics to agricultural science, was formed in 1970 and has since met at approximately yearly intervals in London for one-day meetings. The thirty-fifth meeting of the group, chaired by Dr David Parsons of Silsoe Research Institute, was held in the Kohn Centre at the Royal Society, 6 Carlton House Terrace, London on Friday, 11 April 2003 when the following papers were read.
Metabolic changes within the left dorsolateral prefrontal cortex occurring with electroconvulsive therapy in patients with treatment resistant unipolar depression
Authors: MICHAEL N. , ERFURTH A. , OHRMANN P. , AROLT V. , HEINDEL W. , PFLEIDERER B.
Published: October 2003

Background. The dorsolateral prefrontal cortex (DLPFC) is involved in the pathophysiology of major depression. In particular, metabolic (functional hypometabolism) and structural alterations have been described. In this study metabolic changes within the DLPFC of severely depressed patients before and after electroconvulsive therapy (ECT) were evaluated by proton STEAM spectroscopy (1H-MRS).

Method. Twelve severely depressed patients with a diagnosis of major depressive episode, unipolar with melancholic features (DSM-IV), were enrolled, and the left dorsolateral prefrontal cortex (DLPFC) was investigated before and after unilateral ECT by 1H-MRS. Three of the four non-responding patients were remeasured a third time after a combined ECT/antidepressant pharmacotherapy. The results were compared with 12 age- and gender-matched controls.

Results. In depressed patients reduced glutamate/glutamine (Glx) levels were measured pre-ECT; Glx concentrations correlated negatively with severity of depression. After successful treatment, Glx increased significantly and levels no longer differed from those of age-matched controls.

Conclusions. Our results indicate that major depressive disorder is accompanied by state-dependent metabolic alterations, especially in glutamate/glutamine metabolism, which can be reversed by successful ECT.
Patterns of co-morbidity in male suicide completers
Authors: KIM C. D. , LESAGE A. , SEGUIN M. , CHAWKY N. , VANIER C. , LIPP O. , TURECKI G.
Published: October 2003

Background. Psychiatric co-morbidity is thought to be an important problem in suicide, but it has been little investigated. This study aims to investigate patterns of co-morbidity in a group of male suicide completers.

Method. One hundred and fifteen male suicide completers from the Greater Montreal Area and 82 matched community controls were assessed using proxy-based diagnostic interviews. Patterns of co-morbidity were investigated using latent class analysis.

Results. Three subgroups of male suicide completers were identified (L2=171·62, df=2012, P<0·05), they differed significantly in the amount of co-morbidity (Kruskal–Wallis χ2=71·227, df=2, P<0·000) and exhibited different diagnostic profiles. Co-morbidity was particularly found in subjects with disorders characterized by impulsive and impulsive–aggressive traits, whereas subjects without those traits had levels of co-morbidity which were not significantly different from those of controls (χ2=8·17, df=4, P=0·086).

Conclusions. Suicide completers can be divided into at least three subgroups according to co-morbidity: a low co-morbidity group, a substance-dependent group and a group exhibiting childhood onset of psychopathology.
Climbing Jacob's ladder: John Calvin and the early church on our eucharistic ascent to heaven
Authors: Kaiser Christopher B.
Published: October 2003

In debate with Roman Catholics and Lutherans about the physical presence of Christ in the eucharistic elements, Calvin argued that, since Christ had ascended into heaven (i.e. the spiritual realm or kingdom of God), we must not look for him on the table but ‘lift up our hearts’ to heaven and seek him there. The idea is well known to Calvin scholars, but it still raises many questions. Can Calvin mean that our souls are literally raised up to heaven? Are we supposed to experience some sort of heavenly elevation? And, if this notion is so strange to us, even those of us in Calvinist circles, how was it so readily available to Calvin and his readers? To answer these questions, we shall examine the texts more closely and inquire into their patristic background.
How is the gospel true?
Authors: Reinsdorf Walter
Published: October 2003

In order to answer this question and for other purposes I intend principally to describe, comment on and include some of the thought of Hans Frei and Paul Ricoeur. I include Frei because he, while unable to ‘prove’ Jesus' presence, can ‘make sense of the gospel story’ in his own way, especially with his idea of the ‘history-like’ quality of the story which he believes prevents its acceptance as myth. I too cannot hope to ‘prove’ Jesus’ presence, nor would I account him as mythic. Frei does not, however, account for rhetorical persuasion. While he explains how we can accept the story as true by cutting between history and myth, it still remains to understand why and how the story is offered. But Ricoeur can help to answer the how and the why through his analysis of the coincidence of divine will and human contingency in biblical story, with Jesus as destined and God the Father as Destinator. I take this idea further by showing how in John's gospel Peter, through his own contingent acts of denial, his human fallibility, is rescued by love, the final contingency. Ricoeur also makes a case for ‘manifestation’ rather than ‘verification’ of the gospels, the one through poetic discourse superseding the other by scientific description. Hence, there is a rhetorical – literary argument for reader identity with Jesus, based in part on Aristotle's tragic emotions and in part on our human inconstancy and inconsistency as understood by Ricoeur and Montaigne to show how these qualities work out in Peter. Both Frei and Ricoeur find their way to the Jesus of faith past the Jesus of reason and myth to the Jesus of story. The goal of this article is to show how we are persuaded by John to identify with Jesus with the rhetoric of love.
The von Balthasar thesis: a re-examination of von Balthasar's study of Barth in the light of Bruce McCormack
Authors: Wigley Stephen
Published: October 2003

Von Balthasar's study The Theology of Karl Barth has long been regarded as a seminal work for the interpretation and reception of Barth. Recently its influence has been challenged by Bruce McCormack, who argues that the von Balthasar thesis of a conversion from dialectic to analogy occasioned by Barth's study of Anselm is inadequate. This paper seeks to show not just that there is more to von Balthasar's interpretation than McCormack allows, but also that von Balthasar's study of Barth had a profound influence on his own theological development. In particular, it argues that through his critical engagement with Barth's argument for the analogy of faith against the analogy of being, von Balthasar reassessed the importance of analogy for all theology. In turn, this had a formative impact on his own great trilogy, The Glory of the Lord, Theodrama and Theologic, all of which was based on a christological reading of the analogy of being. Thus, while McCormack may be right on Barth, he is wrong on von Balthasar on Barth.