bluuebunny/crossref_metadata_2025_split huggingface dataset:
Error in an approximate wave function and an error minimization scheme
Authors: Mukhopadhyay S. , Bhattacharyya K. 
Published: December 2003

AbstractAn estimate of error in an approximate wave function for a stationary state is put forward that does not require any information about the exact state. The measure is sensitive and direct. Parameters embedded in a trial wave function can be varied to minimize this error as well, leading to a variational principle. Such a scheme works nicely for bound states and the more so for Siegert states, for which the standard energy minimization principle does not apply. Pilot calculations on the anharmonic oscillator system and the radial Stark effect in the hydrogen atom reveal the worth of the endeavor. © 2003 Wiley Periodicals, Inc. Int J Quantum Chem, 2004
Simple wavefunctions for dipositronium and the relationship between this species and the hydrogen molecule
Authors: Dunne Lawrence J. , Murrell John N. 
Published: December 2003

AbstractDipositronium (two electrons and two positrons) has a closer relationship to the hydrogen molecule than has often been assumed in past treatments. This article shows that appropriately modified mixtures of simple molecular orbital and Heitler–London wavefunctions are a good basis for the ground state of this species. © 2003 Wiley Periodicals, Inc. Int J Quantum Chem, 2004
Long‐range interactions in embedded ionic cluster calculations
Authors: Quintanar Carlos , Caballero Reyna , Köster Andreas M. 
Published: December 2003

AbstractThe effect of long‐range Coulomb interactions on bulk properties is studied for the ionic solids NaBr and NaCl. The embedded cluster approach in the framework of density functional theory is employed. The Madelung potential is calculated with the Evjen cube summation method. To explore the effects of the long‐range interactions on the electron densities and the Madelung constant, the Evjen cube size is varied from 310 to 19650 point charges for 33 atom clusters. To study the size effect of the quantum region, all‐electron clusters with 33 to 87 atoms, embedded in Evjen cubes of 6859 point charges, are investigated. The results show that for the 81 and 87 atom clusters the Madelung potential is constant from the center up to the second neighbor shell. For the same atoms, in all clusters, the electron density at the nuclei has nearly the same value. The largest difference found for the positive ions was 0.54%, and for the negative ions, 0.14%. © 2003 Wiley Periodicals, Inc. Int J Quantum Chem, 2004
Weyl representation of the permutation operators and exchange interaction
Authors: Luzanov A. V. , Prezhdo O. V. 
Published: December 2003

AbstractWeyl phase–space representation is derived for the cyclic permutation operators that naturally occur in the quantum theory of exchange interaction. The classical‐like phase–space representation of exchange leads to a special type of coupling between the position and momentum variables. With Gaussian electronic structure basis sets in mind, it is shown that the position–momentum coupling seen in the Weyl representation of the exchange interaction is best described by diffuse Gaussians. A classical phase–space analog of exchange is derived for the Heisenberg–Dirac spin‐Hamiltonian. Novel one‐electron Wigner functions are introduced for description of the two‐electron spin correlations. © 2003 Wiley Periodicals, Inc. Int J Quantum Chem, 2004
Inertial Sensed Ego‐motion for 3D Vision
Authors: Lobo Jorge , Dias Jorge 
Published: December 2003

AbstractInertial sensors attached to a camera can provide valuable data about camera pose and movement. In biological vision systems, inertial cues provided by the vestibular system are fused with vision at an early processing stage. In this article we set a framework for the combination of these two sensing modalities. Cameras can be seen as ray direction measuring devices, and in the case of stereo vision, depth along the ray can also be computed. The ego‐motion can be sensed by the inertial sensors, but there are limitations determined by the sensor noise level. Keeping track of the vertical direction is required, so that gravity acceleration can be compensated for, and provides a valuable spatial reference. Results are shown of stereo depth map alignment using the vertical reference. The depth map points are mapped to a vertically aligned world frame of reference. In order to detect the ground plane, a histogram is performed for the different heights. Taking the ground plane as a reference plane for the acquired maps, the fusion of multiple maps reduces to a 2D translation and rotation problem. The dynamic inertial cues can be used as a first approximation for this transformation, allowing a fast depth map registration method. They also provide an image independent location of the image focus of expansion and center of rotation useful during visual based navigation tasks. © 2004 Wiley Periodicals, Inc.
Principles of Fusion of Inertial Navigation and Dynamic Vision
Authors: Graovac Stevica 
Published: December 2003

AbstractThe possibility of fusion of navigation data obtained by two separate navigation
systems (strap‐down inertial one and dynamic vision based one)
is considered in this paper. The attention is primarily focused on principles
of validation of separate estimates before their use in a combined algorithm.
The inertial navigation system (INS) based on sensors of medium
level quality has been analyzed on one side, while a visual navigation method
is based on the analysis of a sequence of images of ground landmarks produced
by an on‐board TV camera. The accuracy of INS estimations is being
improved continuously by optimal estimation of a flying object's angular
orientation while the visual navigation system offers discrete corrections
during the intervals of presence of landmarks inside the camera's field
of view. The concept is illustrated by dynamic simulation of a realistic flight
scenario. © 2004 Wiley Periodicals, Inc.
Fusing Visual and Inertial Sensing to Recover Robot Ego‐motion
Authors: Alenyà Guillem , Martínez Elisa , Torras Carme 
Published: December 2003

AbstractA method for estimating mobile robot ego‐motion is presented, which relies on tracking contours in real‐time images acquired with a calibrated monocular video system. After fitting an active contour to an object in the image, 3D motion is derived from the affine deformations suffered by the contour in an image sequence. More than one object can be tracked at the same time, yielding some different pose estimations. Then, improvements in pose determination are achieved by fusing all these different estimations. Inertial information is used to obtain better estimates, as it introduces in the tracking algorithm a measure of the real velocity. Inertial information is also used to eliminate some ambiguities arising from the use of a monocular image sequence. As the algorithms developed are intended to be used in real‐time control systems, considerations on computation costs are taken into account. © 2004 Wiley Periodicals, Inc.
Omnidirectional Vision and Inertial Clues for Robot Navigation
Authors: Stratmann Irem , Solda Erik 
Published: December 2003

AbstractThe structural features inherent in the visual motion field of a mobile robot contain useful clues about its navigation. The combination of these visual clues and additional inertial sensor information may allow reliable detection of the navigation direction for a mobile robot and also the independent motion that might be present in the 3D scene. The motion field, which is the 2D projection of the 3D scene variations induced by the camera‐robot system, is estimated through optical flow calculations. The singular points of the global optical flow field of omnidirectional image sequences indicate the translational direction of the robot as well as the deviation from its planned path. It is also possible to detect motion patterns of near obstacles or independently moving objects of the scene. In this paper, we introduce the analysis of the intrinsic features of the omnidirectional motion fields, in combination with gyroscopical information, and give some examples of this preliminary analysis. © 2004 Wiley Periodicals, Inc.
Electric fields of synaptic currents could influence diffusion of charged neurotransmitter molecules
Authors: Savtchenko Leonid P. , Kulahin Nikolaj , Korogod Sergey M. , Rusakov Dmitri A. 
Published: December 2003

AbstractRapid activation of synaptic receptor‐channels evokes an ion current that flows through the narrow synaptic cleft; this exerts a significant voltage drop and therefore strong electric field (104 V/m range) directed towards the current sinks in the cleft. To what extent this field affects fast diffusion of charged neurotransmitter molecules is not known. We draw a theoretical framework for this complex electrodiffusion phenomenon and establish the basic relationships between the synaptic current and the time course of neurotransmitter in the cleft. The analyses predict that excitatory currents could significantly accelerate the dispersion of negatively charged molecules from the cleft while attracting the positively charged molecules towards the current sinks. This previously unrecognized mechanism should affect the kinetics of synaptic receptor currents, thus contributing to fast synaptic signaling in the brain. Synapse 51:270–278, 2004. © 2003 Wiley‐Liss, Inc.
Changes in PKA activity and Gsα and Golfα levels after amphetamine‐ and cocaine‐induced behavioral sensitization
Authors: Crawford Cynthia A. , Choi Fiona Y. , Kohutek Jodi L. , Yoshida Shelly T. , Mcdougall Sanders A. 
Published: December 2003

AbstractNeuroadaptations in the cAMP signal transduction system have been proposed to play a critical role in psychostimulant‐induced behavioral sensitization. Studies relevant to this hypothesis have provided conflicting evidence, however, because repeated cocaine and amphetamine treatment has been alternately reported to either increase or decrease protein kinase A (PKA) activity in the nucleus accumbens and dorsal striatum. In an attempt to reconcile these disparate findings, PKA activity and the stimulatory G‐protein subunits, Gsα and Golfα, were measured after rats had received a sensitization‐inducing regimen of amphetamine or cocaine. Results showed that seven consecutive daily injections of amphetamine or cocaine produced locomotor sensitization and caused a reduction in accumbal PKA activity. A challenge injection of amphetamine on the test day also reduced dorsal striatal PKA activity. Gsα levels were unaffected by psychostimulant exposure, while Golfα levels in the nucleus accumbens declined significantly after amphetamine or cocaine pretreatment. Because repeated amphetamine and cocaine treatment both induced behavioral sensitization and decreased accumbal PKA activity, it appears that psychostimulant‐induced increases in PKA activity are not necessary for the ultimate expression of behavioral sensitization. Synapse 51:241–248, 2004. © 2003 Wiley‐Liss, Inc.
Clozapine and dopamine D3 receptor antisense reduce cocaine‐ and amphetamine‐regulated transcript expression in the rat nucleus accumbens shell
Authors: Beaudry Geneviève , Zekki Hakima , Rouillard Claude , Lévesque Daniel 
Published: December 2003

AbstractCocaine‐ and amphetamine‐regulated transcript (CART) is a neuropeptide highly expressed in the hypothalamus and nucleus accumbens. Hypothalamic CART has been associated with food intake and body weight control, but in the nucleus accumbens the role of CART remains elusive. New generations of antipsychotic drugs show a good efficacy over psychotic symptoms but they induce an important weight gain. The mechanism underlying this unexpected side effect is still unknown. The present results show, for the first time, that acute and chronic treatment with the atypical neuroleptic clozapine, but not the conventional neuroleptic haloperidol, reduced the expression of CART mRNA in the shell of the nucleus accumbens. CART mRNA is colocalized with both dopamine D2 and D3 receptor transcripts in the nucleus accumbens shell. However, a dopamine D3 receptor, but not D2, antisense oligonucleotide administration reduced CART expression in this brain area. These results suggest that the dopamine D3 receptor, but not the D2, is involved in the control of CART expression in the nucleus accumbens and that it may participate in the modulation of CART mRNA levels by clozapine. The modulation of CART, an anorexigenic neuropeptide, in the dopamine mesolimbic pathway may potentially play a role in dysregulated food intake induced by some antipsychotic drugs. Synapse 51:233–240, 2004. © 2003 Wiley‐Liss, Inc.
Loss of nicotine‐induced behavioral sensitization in μ‐opioid receptor knockout mice
Authors: Yoo Ji‐Hoon , Lee Seok‐Yong , Loh Horace H. , Ho Ing K. , Jang Choon‐Gon 
Published: December 2003

AbstractRepeated administration of nicotine produces behavioral sensitization. However, the possible mechanism of behavioral sensitization to nicotine remains unclear. The present study was undertaken in μ‐opioid receptor knockout mice, to examine the hypothesis that μ‐opioid receptors play a crucial role in behavioral sensitization to nicotine. All mice received saline or nicotine (0.05 mg/kg, s.c) twice a day for 7 consecutive days. The mice remained drug free for 3 days and on day 11 each group was challenged with saline or nicotine (0.05 mg/kg, s.c.). On day 1, it was observed that the single injection of nicotine (0.05 mg/kg, s.c.) did not influence locomotor activity in either μ‐opioid receptor knockout or in wildtype mice. On day 7 (24 h after mice had been treated twice daily for 6 consecutive days with an injection of 0.05 mg/kg of nicotine), the mice were challenged with a single injection of nicotine, which produced behavioral sensitization in the wildtype but not in μ‐opioid receptor knockout mice. On day 11, following 3 days of withdrawal after the second injection of nicotine on day 7, nicotine‐treated mice were challenged with a single injection of nicotine and showed the behavioral sensitization of wildtype. However, nicotine challenge did not induce behavioral sensitization in μ‐opioid receptor knockout mice. Our data indicate that a lack of μ‐opioid receptors can inhibit the effects of nicotine‐induced behavioral sensitization. This result strongly suggests that the μ‐opioid receptor plays an important role in behavioral sensitization to nicotine. Synapse 51:219–223, 2004. © 2003 Wiley‐Liss, Inc.
Lesion of subthalamic or motor thalamic nucleus in 6‐hydroxydopamine‐treated rats: Effects on striatal glutamate and apomorphine‐induced contralateral rotations
Authors: Touchon Justin C. , Moore Cynthia , Frederickson Julie , Meshul Charles K. 
Published: December 2003

AbstractA unilateral lesion of the rat nigrostriatal pathway with 6‐hydroxydopamine (6‐OHDA) results in a decrease in the basal extracellular level of striatal glutamate, a nearly complete loss of tyrosine hydroxylase (TH) immunolabeling, an increase in the density of glutamate immunogold labeling within nerve terminals making an asymmetrical synaptic contact, and an increase in the number of apomorphine‐induced contralateral rotations. [Meshul et al. (1999) Neuroscience 88:1–16; Meshul and Allen (2000) Synapse 36:129–142]. In Parkinson's disease, a lesion of either the subthalamic nucleus (STN) or the motor thalamic nucleus relieves the patient of some of the motor difficulties associated with this disorder. In this rodent model, either the STN or motor thalamic nucleus was electrolytically destroyed 2 months following a unilateral 6‐OHDA lesions. Following a lesion of either the STN or motor thalamic nucleus in 6‐OHDA‐treated rats, there was a significant decrease (40–60%) in the number of apomorphine‐induced contralateral rotations compared to the 6‐OHDA group. There was a significant decrease (<30%) in the basal extracellular level of striatal glutamate in all of the experimental groups compared to the sham group. Following an STN and/or 6‐OHDA lesion, the decrease in striatal extracellular levels was inversely associated with an increase in the density of nerve terminal glutamate immunolabeling. There was no change in nerve terminal glutamate immunogold labeling in either the motor thalamic or motor thalamic plus 6‐OHDA lesion groups compared to the sham group. The decrease in the number of apomorphine‐induced rotations was not due to an increase in TH immunolabeling (i.e., sprouting) within the denervated striatum. This suggests that alterations in striatal glutamate appear not to be directly involved in the STN or motor thalamic lesion‐induced reduction in contralateral rotations. Synapse 51:287–298, 2004. Published 2003 Wiley‐Liss, Inc.
Gene expression profiling in the midbrain of striatal 6‐hydroxydopamine‐injected mice
Authors: Iwata Shin‐Ichi , Nomoto Masahiro , Morioka Hirofumi , Miyata Atsuro 
Published: December 2003

AbstractIn order to clarify mechanisms underlying dopaminergic neuronal death in Parkinson's disease (PD), a gene expression profiling study was performed in a rodent model of PD. In this model, mice are intrastriatally injected with 6‐hydroxydopamine (6‐OHDA) and dopaminergic neurons in the substantia nigra (SN) gradually die by retrograde degeneration. The SN were removed 2 h, 24 h, or 14 days after 6‐OHDA administration. Levels of mRNAs related to cell death or survival were quantified using adaptor‐tagged competitive PCR (ATAC‐PCR). The cyclin D1 gene showed an immediate increase in mRNA expression. After 24 h, when dopaminergic neurons were under intense degeneration, levels of caspase 8 mRNA and p53 apoptosis effecter related to pmp 22 (PERP) mRNA increased and, conversely, FAS mRNA decreased. After 14 days, when the degeneration was attenuated, levels of PERP mRNA and serum‐ and glucocorticoid‐regulated kinase (SGK) mRNA still increased. SGK has a similarity to AKT, which is an important molecule involved in nerve growth factor signal transduction. AKT mRNA levels are low in dopaminergic neurons. These results suggest that an increase in cyclin D1 mRNA triggers dopaminergic neurons to enter an abnormal cell cycle, which leads to neuronal degeneration and cell death, possibly induced by PERP and caspase 8. In addition to cell death‐related genes, several survival‐related genes are activated. SGK might function as a key enzyme for the survival of dopaminergic neurons. Synapse 51:279–286, 2004. © 2003 Wiley‐Liss, Inc.
Synthesis and Structure of the First Three‐legged Low‐dimensional Iron Phosphate, [H3N(CH2)3NH2(CH2)2NH2(CH2)3NH3][Fe3F6(HPO4)2(PO4)]·3H2O
Authors: Mandal Sukhendu , Pati Swapan K. , Green Mark A. , Wang Sue‐Lein , Natarajan Srinivasan 
Published: December 2003

AbstractA hydrothermal reaction of iron acetylacetonate, phosphoric acid, HF, N, N′‐bis(3‐aminopropyl)ethylenediamine and water at 150 °C gave rise to a new iron phosphate, [H3N(CH2)3NH2(CH2)2NH2(CH2)3NH3][Fe3F6(HPO4)2(PO4)] · 3H2O (I). The structure consists of Fe(1)O4F2, Fe(2)O3F3 octahedral and P(1)O3(OH) and P(2)O4 tetrahedral building units connected through their vertices to form fragments of tancoite‐type units. The tancoite‐type units are linked through the phosphate tetrahedra forming an unusual iron phosphate with a hitherto unknown low‐dimensional structure with three‐iron center.Magnetic studies indicate a complex behavior at low temperature and the high‐temperature data (150 — 300 K) has a Curie‐Weiss behavior. The calculated room temperature magnetic moment is 6 μB per Fe atom, and the Neel temperature, TN = 46K. Crystal data: orthorhombic, space group = I212121 (no. 24), a = 9.9042(11), b = 12.8865(14), c = 19.783(2)Å, U = 2524.9(5), Z = 4.
Preparation of 1‐X‐2, 2‐Difluoroethenylxenon(II) Tetrafluoroborates [CF2=CXXe][BF4]
Authors: Frohn Hermann‐Josef , Bardin Vadim V. 
Published: December 2003

AbstractThe new type of alkenylxenon(II) salts [CF2=CXXe] [BF4] (X = H, Cl, CF3) was prepared by reacting the corresponding alkenyldifluoroboranes CF2=CXBF2 with XeF2 in 1, 1, 1, 3, 3‐pentafluoropropane (PFP) at —60 °C. The alkenylxenon(II) salts were characterised by multinuclear NMR spectroscopy. The influence of the substituent X at C‐1 on the stability of alkenylxenon(II) salts is discussed. Additionally the preparation of the potassium alkenyltrifluoroborate salts K [CF2=CXBF3] and their transformation into the boranes CF2=CXBF2 by fluoride abstraction in PFP is reported.
Metal‐Xenon Complexes
Authors: Seppelt Konrad 
Published: December 2003

AbstractLong after the first isolation of a xenon compound in 1962 the first compounds with metal‐xenon bonds are prepared. The metal atoms are so far Au and Hg. The most stable metal xenon compounds decompose under loss of xenon slightly above room temperature. They can only exist if solvents and counter ions are weaker bases than atomic xenon. Solvents and counter ions used so far are HF, (SbF6)—, and (Sb2F11)—.
Two Mercury Chloro Thiocyanate Complexes: NH4[HgCl2(SCN)] and NH4[HgCl(SCN)2]
Authors: Gacemi Aissa , Benbertal Djamal , Bagieu‐Beucher Muriel , Lecchi Amélie , Mosset Alain 
Published: December 2003

AbstractSingle crystals of NH4[HgCl2(SCN)] (1) and NH4[HgCl(SCN)2] (2) are obtained by slow evaporation of ethanol solutions of HgCl2 and NH4SCN or Hg(SCN)2 and NH4Cl. 1 crystallizes in the monoclinic space group P21 (a = 9.297(1), b = 4.171(1), c = 9.198(1)Å, β = 92.827(5)°). The structure consists in HgCl2(SCN) linear chains, extending along the twofold axis, connected through the ammonium ions. 2 crystallizes in the monoclinic space group C2/c (a = 7.088(1), b = 19.986(2), c = 5.958(1)Å, β = 100.718(5)°). The structure consists of HgCl(SCN)2 molecules connected through the ammonium ions. The second order non linear optical properties of 1 are discussed.
Alkali‐Metal ortho‐Hydroxyphenolates: Syntheses and Crystal Structures from Powder X‐Ray Diffraction
Authors: Couhorn Uwe , Dronskowski Richard 
Published: December 2003

AbstractColorless and highly air‐ and moisture‐sensitive powders of M[o‐C6H4O(OH)] with M = K, Rb, or Cs have been synthesized from reaction mixtures of the appropriate alkali metal and catechol in thf. All compounds were structurally characterized by means of powder X‐ray diffraction using the Rietveld profile refinement technique including restraints for the C—C/C—O bond distances and the C—C—C angles. The atomic arrangements of M[o‐C6H4O(OH)] (K: monoclinic P21/c; Rb/Cs: orthorhombic Pbcm) are characterized by polymeric chains of [M1[4]O2[2]η6] units connected by hydrogen bonds, thereby making up layered structures similar to the one of catechol. The coordinatively unsaturated alkali metals are forming edge‐sharing MO4 pyramids and exhibit asymmetrical η6‐interactions with the phenylene rings. The symmetry of the unit cells increases with increasing size of the cation, and this results in a decrease of the monoclinic angle from 118.5° (catechol) to 93.7° (K compound), eventually leading to orthorhombic cells for the Rb and Cs compounds.
Die Kristallstrukturen von (NBu4)[(Ph3Sn)3(MoO4)2] und (NBu4)[(Ph3Sn)3(MoO4)2]·CH3CN: Organozinnmolybdate mit neuartigen 3D‐Netzwerken
Authors: Rosenland F. , Kondracka M. , Merzweiler K. 
Published: December 2003

AbstractDie Umsetzung von (NBu4)2[Mo6O19] mit Ph3SnCl und (NBu4)OH in Acetonitril als Lösungsmittel führt zur Bildung von (NBu4)[(Ph3Sn)3(MoO4)2] (5). 5 und (NBu4)[(Ph3Sn)3(MoO4)2]·CH3CN (6) wurden durch Kristallstrukturanalysen charakterisiert. 5 kristallisiert monoklin in der Raumgruppe Cc mit den Gitterkonstanten (220 K): a = 1429, 5(4) pm, b = 2292, 2(3) pm, c = 2269, 7(5) pm, β = 107, 42(3)°. 6 kristallisiert orthorhombisch in der Raumgruppe P212121 mit den Gitterkonstanten (220 K): a = 1820, 5(1) pm, b = 1848, 6(2) pm and c = 2143, 9(1) pm. Die Kristallstrukturen von 5 und 6 bestehen aus isolierten (NBu4)+‐Kationen und anionischen 3D Netzwerken, die aus eckenverknüpften Ph3SnO2‐Bipyramiden und MoO4‐Tetraedern aufgebaut sind.