bluuebunny/crossref_metadata_2025_split huggingface dataset:
Methylene blue blocks cGMP production and disrupts directed migration of microglia to nerve lesions in the leech CNS
Authors: Duan Yuanli , Haugabook Sharie J. , Sahley Christie L. , Muller Kenneth J. 
Published: October 2003

AbstractMigration and accumulation of microglial cells at sites of injury are important for nerve repair. Recent studies on the leech central nervous system (CNS), in which synapse regeneration is successful, have shown that nitric oxide (NO) generated immediately after injury by endothelial nitric oxide synthase (eNOS) stops migrating microglia at the lesion. The present study obtained results indicating that NO may act earlier, on microglia migration, and aimed to determine mechanisms underlying NO's effects. Injury induced cGMP immunoreactivity at the lesion in a pattern similar to that of eNOS activity, immunoreactivity, and microglial cell accumulation, which were all focused there. The soluble guanylate cyclase (sGC) inhibitor methylene blue (MB) at 60 μM abolished cGMP immunoreactivity at lesions and blocked microglial cell migration and accumulation without interfering with axon conduction. Time‐lapse video microscopy of microglia in living nerve cords showed MB did not reduce cell movement but reduced directed movement, with significantly more cells moving away from the lesion or reversing direction and fewer cells moving toward the lesion. The results indicate a new role for NO, directing the microglial cell migration as well as stopping it, and show that NO's action may be mediated by cGMP. © 2003 Wiley Periodicals, Inc. J Neurobiol 57: 183–192, 2003
Androgens and estrogens induce seasonal‐like growth of song nuclei in the adult songbird brain
Authors: Tramontin Anthony D. , Wingfield John C. , Brenowitz Eliot A. 
Published: October 2003

AbstractIn seasonally breeding songbirds, the brain regions that control song behavior undergo dramatic structural changes at the onset of each annual breeding season. As spring approaches and days get longer, gonadal testosterone (T) secretion increases and triggers the growth of several song control nuclei. T can be converted to androgenic and estrogenic metabolites by enzymes expressed in the brain. This opens the possibility that the effects of T may be mediated via the androgen receptor, the estrogen receptor, or both. To test this hypothesis, we examined the effects of two bioactive T metabolites on song nucleus growth and song behavior in adult male white‐crowned sparrows. Castrated sparrows with regressed song control nuclei were implanted with silastic capsules containing either crystalline T, 5α‐dihydrotestosterone (DHT), estradiol (E2), or a combination of DHT+E2. Control animals received empty implants. Song production was highly variable within treatment groups. Only one of seven birds treated with E2 alone was observed singing, whereas a majority of birds with T or DHT sang. After 37 days of exposure to sex steroids, we measured the volumes of the forebrain song nucleus HVc, the robust nucleus of the archistriatum (RA), and a basal ganglia homolog (area X). All three steroid treatments increased the volumes of these three song nuclei when compared to blank‐implanted controls. These data demonstrate that androgen and estrogen receptor binding are sufficient to trigger seasonal song nucleus growth. These data also suggest that T's effects on seasonal song nucleus growth may depend, in part, upon enzymatic conversion of T to bioactive metabolites. © 2003 Wiley Periodicals, Inc. J Neurobiol 57:130–140, 2003
Neuromuscular activity impairs axonal sprouting in partially denervated muscles by inhibiting bridge formation of perisynaptic Schwann cells
Authors: Tam S. L. , Gordon T. 
Published: October 2003

AbstractFollowing partial denervation of rat hindlimb muscle, terminal Schwann cells extend processes from denervated endplates to induce and guide sprouting from the remaining intact axons. Increased neuromuscular activity significantly reduces motor unit enlargement and sprouting during the acute phase of sprouting. These findings led to the hypothesis that increased neuromuscular activity perturbs formation of Schwann cell bridges and thereby reduces sprouting. Adult rat tibialis anterior (TA) muscles were extensively denervated by avulsion of L4 spinal root and were immediately subjected to normal caged activity or running exercise (8 h daily) for 3, 7, 14, 21, and 28 days. Combined silver/cholinesterase histochemical staining revealed that the progressive reinnervation of denervated endplates by sprouts over a 1 month period in the extensively partially denervated TA muscles was completely abolished by increased neuromuscular activity. Immunohistochemical staining and triple immunofluorescence revealed that the increased neuromuscular activity did not perturb the production of Schwann cell processes, but prevented bridging between Schwann cell processes at innervated and denervated endplates. Our findings suggest that failure of Schwann cell processes to bridge between endplates accounts, at least in part, for the inhibitory effect of increased neuromuscular activity on sprouting. © 2003 Wiley Periodicals, Inc. J Neurobiol 57: 221–234, 2003
Changes in trabecular bone structure in rickets and osteomalacia: the potential of a medico‐historical collection
Authors: Schamall D. , Teschler‐Nicola M. , Kainberger F. , Tangl St. , Brandstätter F. , Patzak B. , Muhsil J. , Plenk H. 
Published: October 2003

AbstractIn this study lumbar vertebral bodies with and without disturbed mineralization from a medico‐historical collection of the 19th century (housed in the Federal Museum for Pathological Anatomy, Vienna) were investigated, using non‐invasive radiological and invasive histological techniques. Macerated, or partly dissected, or fixation fluid conservated skeletal preparations from 61 individuals with known age and gender were examined. The specimens of 37 individuals had gross pathologic alterations from rickets or osteomalacia. The specimens from 24 individuals without Known bone disease served as age‐matched controls. Bone structure and mineralization in all specimens were evaluated by non‐invasive techniques (conventional radiographs and computed tomography). Thirteen selected specimens from both groups were also analysed by quantitative computed tomography (qCT) and dual‐energy X‐ray absorptiometry (DEXA). In these cases invasive techniques (light and scanning electron microscopy [backscattered electron (BSE)‐ and secondary electron (SE)‐mode] on surface‐stained and carbon‐sputtered undecalcified histological ground sections) were applied. Corresponding microradiographs were also used for computer‐assisted morphometry. The clinically established method of determination of bone mineral densities (BMD) by qCT and DEXA failed in these historical specimens, but all other non‐invasive and invasive techniques were successfully applied and yielded results corresponding to radiological changes and histomorphometric parameters. In the rachitic vertebrae it was not volume densities (bone volume per tissue volume = BV/TV), but numbers of trabeculae (trabecular number = Tb.N.) which were increased, compared to the age‐matched vertebral bodies without bone disease. In osteomalacic vertebrae the volume densities (BV/TV) were decreased in the whole vertebral body, while Tb.N. were only decreased in the middle third of the vertebral body. Accordingly, surface densities (SV) in non‐adults, and also specific surfaces (S/V) in adults were increased, suggesting increased bone resorption. Depending on the preparation technique used in the present study, resorption lacunae and characteristic unmineralized osteoid seams could be demonstrated. In conclusion, it might be useful to establish such techniques and standards for the diagnosis of disturbed mineralization in clinical patients. Copyright © 2003 John Wiley & Sons, Ltd.
Shape sensitivities in a Navier‐Stokes flow with convective and grey bodies radiative thermal transfer
Authors: Monnier J. 
Published: October 2003

AbstractWe study a shape optimal design problem for a forced convection flow: the steady‐state Navier–Stokes equations coupled with an integro‐differential thermal model. The thermal transfers are convective, diffusive and radiative with multiple reflections (model of grey bodies, radiosity equation). The inverse problem consists in minimizing a smooth cost function which depends on the solution, with respect to the domain of the equations. We prove the differentiability of the solution with respect to the domain. It follows the cost function differentiability. We introduce the adjoint state equation and obtain the exact differential of the cost function. The computational method of shape sensitivities and the optimization process are presented too. Copyright © 2003 John Wiley & Sons, Ltd.
Using logarithmic penalties in the shooting algorithm for optimal control problems
Authors: Bonnans J. F. , Guilbaud Th. 
Published: October 2003

AbstractThe paper deals with optimal control problems of ordinary differential equations with bound control constraints. We analyse the logarithmic penalty method for converting the problem into an unconstrained one, the latter being solved by a shooting algorithm. Convergence of the value function and optimal controls is obtained for linear quadratic problems, and more generally when the control variable enters linearly in the state equation and in a quadratic way in the cost function. We display some numerical results on two examples: an aircraft maneuver, and the stabilization of an oscillating system. Copyright © 2003 John Wiley & Sons, Ltd.
Solving multi‐objective dynamic optimization problems with fuzzy satisfying method
Authors: Chen Cheng‐Liang , Chang Chia‐Yuan , Sun Daim‐Yuang 
Published: October 2003

AbstractThis article proposes a novel algorithm integrating iterative dynamic programming and fuzzy aggregation to solve multi‐objective optimal control problems. First, the optimal control policies involving these objectives are sequentially determined. A payoff table is then established by applying each optimal policy in series to evaluate these multiple objectives. Considering the imprecise nature of decision‐maker's judgment, these multiple objectives are viewed as fuzzy variables. Simple monotonic increasing or decreasing membership functions are then defined for degrees of satisfaction for these linguistic objective functions. The optimal control policy is finally searched by maximizing the aggregated fuzzy decision values. The proposed method is rather easy to implement. Two chemical processes, Nylon 6 batch polymerization and Penicillin G fed‐batch fermentation, are used to demonstrate that the method has a significant potential to solve real industrial problems. Copyright © 2003 John Wiley & Sons, Ltd.
Ab initio CI calculations of the potential curves and nonadiabatic coupling matrix elements for collisions of protons with the ethylene molecule
Authors: Rai Sachchida N. , Liebermann Heinz‐Peter , Buenker Robert J. , Kimura Mineo 
Published: October 2003

AbstractThe interaction of ethylene with a single proton has been studied theoretically by means of multireference configuration interaction calculations. Potential energy surfaces have been obtained as well as both radial and rotational nonadiabatic coupling matrix elements. Three different approaches of the proton toward the midpoint of the target molecule have been considered for eight collision channels. Along the π direction a number of deep potential minima have been found and the ground‐state proton affinity is calculated to be 7.25 eV on this basis. There is a strongly avoided crossing in this case between the higher‐energy C2H4/H+ incoming channel and the ground C2H/H singlet state, and the corresponding radial coupling matrix element has a broad shape as a result. For the approaches along the in‐plane perpendicular axes of the molecule there is a potential crossing for these two states due to their different symmetries in these orientations, from which it is clear that the incoming channel is strongly bound whereas the charge‐transfer state is repulsive. Comparison with available experimental results indicates that the computed energy differences between the electronic states are accurate to within 0.1–0.2 eV. For the approach along the CC bond there is a weakly avoided crossing between the lowest triplet state of C2H4 and the C2H state corresponding to ionization from the σ molecular orbital (MO). One of the potential minima occurring for the π approach is seen to result from a doubly excited state in which the two π electrons are transferred to a π* MO and the incoming proton, respectively, so that a relatively stable three‐center bond is formed. © 2003 Wiley Periodicals, Inc. Int J Quantum Chem, 2003
The strain energy of perchlorocyclopropane is small: It might even be negative. A density functional theory study of perhalocycloalkanes
Authors: Mahavadi Madhavi , Zeiger Diana N. , Naqib Dahlia , Roux Maria Victoria , Notario Rafael , Liebman Joel F. 
Published: October 2003

AbstractThe strain energy for the parent, perfluoro‐, and perchlorocycloalkanes (CnX2n, X = H, F, and Cl, n = 3–6) is evaluated using a variety of equations (homodesmotic, group increment, and diagonal) and density functional theory calculations [B3P86/6‐311+G(2df,p)//6‐311G(d)]. Literature trends are reproduced for the fluorinated species. Results, although explained, for chlorinated compounds are still a source of surprise: The strain energy of perchlorocyclopropane is small and may well be negative. © 2003 Wiley Periodicals, Inc. Int J Quantum Chem, 2003
Molecular quadrupole moments of HCCH, FCCF, and ClCCCl
Authors: Gearhart Dorothy J. , Harrison James F. , Hunt Katharine L. C. 
Published: October 2003

AbstractThe molecular quadrupole moments of HCCH, FCCF, and ClCCCl have been studied as a function of basis set at the self‐consistent field, density functional theory (B3LYP), and CCSD(T) levels. The CCSD(T) results, in units of ea, are 4.856 (HCCH), −0.6389 (FCCF), and 3.7685 (ClCCCl). When corrected for vibration, the HCCH result is reduced to 4.795 and is in excellent agreement with experiment, 4.71 ± 0.14. There are no experimental data for FCCF and ClCCCl. The molecular quadrupole moments are shown to have the form Θ = Θatoms + Θcr, where Θatoms is the sum of the quadrupole moments of the separated atoms and Θcr is the contribution due to charge redistribution upon molecule formation. This model accounts for the magnitude and signs of Θ in this series. © 2003 Wiley Periodicals, Inc. Int J Quantum Chem, 2003
Effect of metal complexation on ring opening of bowl‐shaped hydrocarbons: Theoretical study
Authors: Jemmis Eluvathingal D. , Parameswaran Pattiyil , Anoop Anakuthil 
Published: October 2003

AbstractDensity 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

AbstractDissociative 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

AbstractSeveral 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

AbstractThis 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

AbstractWe 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

AbstractMolecular 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

AbstractMicrowave 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

AbstractFor 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