bluuebunny/crossref_metadata_2025_split huggingface dataset:
Coulomb Forces in Three Charged Particles Interacting via Stripping Nuclear Reactions
Authors: Osman Ahmed 
Published: May 2007

AbstractCoulomb forces are examined for three charged interacting particles following the Faddeev formalism. Application of stripping nuclear reactions is studied for 6Li projectile incident on 12C target with alpha particle transfer. Differential corss‐sections are calculated. The results are found to be improved by about 12.41% due to the inclusion of the Coulomb forces.
Multi Soliton Solution for Langmuir Ion‐Acoustic System in an Arbitrary Background
Authors: Chowdhury A. Roy , Mahato G. 
Published: May 2007

AbstractWe have found compact formulas for the general N‐Soliton Solution for Langmuir Ion Acoustic System through the dressing‐up technique proposed by Neugebauer et al. In this approach the initial solution can be any solution known as ‘seed solution’ which is referred to as the ‘arbitrary background’.
Thermodynamic Functions, Ionization Equilibrium and Phase Transitions in Coulomb Systems
Authors: Kraeft W. D. , Ebeling W. , Kremp D. , Röpke G. 
Published: May 2007

AbstractMacroscopic matter is considered as a quantum statistical system of electrons and nuclei. After the discussion of several exact bounds and stability theorems, the low and high density structures of the thermodynamic functions (corresponding to ideal gases) are given. The intermediate regions in the density temperature plane are treated by means of thermodynamic Green functions. This requires partial summations corresponding to the effects of screening (chains), bound states (ladders), and chemical equilibria (quasi particle summations). The thermodynamic instabilities corresponding to the first order plasma phase transitions are studied for several examples.
Removal of Chiral Anomalies in Abelian Gauge Theories
Authors: Kaschluhn F. 
Published: May 2007

AbstractIt is shown that chiral anomalies can be removed in abelian gauge theories. After a discussion of the two dimensional case where exact solutions are available we study the four dimensional theory. We use perturbation theory, i. e. analyse the triangle Feynman integrals, and determine the general subtraction structure of the gauge current. Then we show that gauges exist for which current conservation holds and the theory is gauge invariant. As far as the generating functional is concerned the anomaly is employed first as gauge fixing condition. After rewriting the interaction in a gauge invariant form the gauge fixing condition can be imposed as usual. In our approach the integration over the gauge group remains trivial.
Hadronic Interactions in the Energy Region of Future Hadron Colliders, Dual Topological Unitarization of Hard and Soft Hadronic Cross Sections
Authors: Ranft J. 
Published: May 2007

AbstractThe dual topological unitarization of hard and soft hadronic collisions is formulated as a Monte Carlo event generator for events containing both the soft (lowp∂) and hard (jets, minijets) component of hadron production. The parameters of the model are determined from fits to the energy dependence of the total and inelastic hadron cross‐sections and from the predictions of the QCD‐parton model for the perturbative hard constituent scattering cross sections. The predictions of the model for TeV colliders are presented. Interesting changes of the produced multiparticle system are found when selecting classes of events with and without hard jets or minijets.
Über Interferenzen und Intensitätskorrelationen bei Lichtstrahlen sehr geringer Intensität
Authors: Richter G. 
Published: May 2007

AbstractDie im Wellenfeld zweier sich kreuzender Lichtstrahlen auftretenden Interferenzen und Korrelationen zwischen den Intensitäten an zwei verschiedenen Orten zur gleichen Zeit werden in klassischer und quantentheoretischer Sicht berechnet, und die bei sehr kleinen Lichtstärken meßbaren Unterschiede mit neueren experimentellen Ergebnissen von L. Mandel und Mitarb. verglichen.
The Concept of Energy Densities and Stress Fields and its Applications in Quantum Mechanical Coulomb Systems within the Born‐Oppenheimer Approximation
Authors: Ziesche P. 
Published: May 2007

AbstractRecent papers and ideas concerning the global stress for crystals (obtained by a scaling of the total energy) as well as local stress and local energy (expressed by reduced density matrices or by Kohn‐Sham orbitals) and related theorems and quantities like local momentum balances, forces, force sum rules, defect energies and defect stresses for perturbed crystals (surfaces, interfaces, point defects) are summarized. A new method for the calculation of relaxation or restoring forces is emphasized.
Electrons with alternating on‐site and correlated hopping interactions
Authors: Japaridze G. , Müller‐Hartmann E. 
Published: May 2007

AbstractThe 1 D one‐band Hubbard model with different repulsive on‐site interactions on even (U+V > 0) and odd (U‐V > 0) sites, supplemented by the correlated‐hopping term (t* > 0), describing the modification of the electron hopping by the presence of other particles on the sites, is considered as a 1 D model for CuO systems. The ground state phase diagram is studied within the framework of the bosonization technique and renormalization group analysis valid for weak coupling. Depending on the choice of model parameters, the following sequences of phase transitions with increasing bandfilling occur: 1) metal‐insulator‐metal (for t* ⩽ U/4); 2) metal‐insulator‐metal‐superconductor \documentclass{article}\pagestyle{empty}\begin{document}$ ({\rm for}U/4 < t * \le U/\sqrt 8);3) $\end{document}metal‐superconductor‐metal‐insulator‐metal‐superconductor \documentclass{article}\pagestyle{empty}\begin{document}$ ({\rm for}U/\sqrt 8 \le t * < (U + V)/\sqrt 8){\rm and}4) $\end{document}metal‐superconductor \documentclass{article}\pagestyle{empty}\begin{document}$ ({\rm for}(U + V)/\sqrt 8 \le t*) $\end{document}.
X‐ray photoemission spectra measurements of CeNi2Sb2 and CeCu2Sb2
Authors: Ślebarski A. , Neumann M. , Mähl S. , Pierre J. , Kaczmarska K. 
Published: May 2007

AbstractX‐ray photoemission spectra, resistivity and susceptibility of CeNi2Sb2 and CeCu2Sb2 were measured and are discussed. The results indicate that these alloys are Kondo systems. For comparison of the valence band properties, the spectra of the isostructural alloys of RT2X2‐type with R = La, Gd, T = Cu, Ni and X = Sn, Sb were investigated, too.
Surface self‐diffusion of quench condensed hydrogen films
Authors: Classen J. , Eschenröder K. , Weiss G. 
Published: May 2007

AbstractThe annealing behaviour of quench condensed H2‐, HD‐ and D2‐films has been investigated using acoustic surface waves. Upon annealing at temperatures far below the triple point we observe drastic changes of sound velocity and attenuation which can be attributed to a considerable rearrangement of the film structure via surface diffusion. These findings are in good agreement with recent experiments using surface plasmons. From the temperature dependence of the speed of the structural changes we deduce the activation energies for surface self‐diffusion as 23 K, 35 K, and 47 K for H2, HD, and D2, respectively.
Brillouin scattering of vitreous silica under high pressure
Authors: Rau S. , Baeßler S. , Kasper G. , Weiss G. , Hunklinger S. 
Published: May 2007

AbstractThe pressure dependence of Brillouin spectra of vitreous silica exhibits a maximum in the hypersonic absorption and a minimum in the sound velocity at about 2 GPa almost independent of temperature. The results are discussed on the basis of relaxing defects residing in double‐well potentials with a Gaussian distribution of barrier heights and a Lorentzian distribution in the asymmetry. Our analysis suggests that both the distribution functions are strongly changed at higher pressures. It is striking that a phase boundary between α‐quartz and coesite exists just at the pressure where absorption and sound velocity of vitreous silica pass their extremum. This might be a hint that a corresponding structural change also occurs in the glass.
Conductivity of a small metallic particle
Authors: Schaefer F. C. , v. Baltz R. 
Published: May 2007

AbstractThe size‐dependent ac‐conductivity of a small metallic particle is studied for electrons enclosed in a box with random impurities. The exact wave functions and energies are calculated numerically up to 500 electrons, then the Kubo‐formula is evaluated, and an ensemble average is performed. A strong size‐ and frequency dependence of the conductivity is found which is in good agreement with random matrix results. The size dependence of the dc‐conductivity agrees qualitatively with microwave absorption measurements on submicron particles.
Partial wave analysis in K‐matrix formalism
Authors: Chung S. U. , Brose J. , Hackmann R. , Klempt E. , Spanier S. , Strassburger C. 
Published: May 2007

AbstractA description is given of the K‐matrix formalism. The formalism, which is normally applied to two‐body scattering processes, is generalized to production of two‐body channels with finalstate interactions. A multi‐channel treatment of production of resonances has been worked out in the P‐vector approach of Aitchison. An alternative approach, derived from the P‐vector, gives the production amplitude as a product of the T‐matrix for a two‐body system and a vector Q specifying its production. This formulation, called Q‐vector approach here, has also been worked out. Examples of practical importance are given.
Driven interface depinning in a disordered medium
Authors: Leschhorn Heiko , Nattermann Thomas , Stepanow Semjon , Tang Lei‐Han 
Published: May 2007

AbstractThe dynamics of a driven interface in a medium with random pinning forces is analyzed. The interface undergoes a depinning transition where the order parameter is the interface velocity v, which increases as v ∼(F Fc)θ for driving forces F close to its threshold value Fc. We consider a Langevin‐type Eq. which is expected to be valid close to the depinning transition of an interface in a statistically isotropic medium. By a functional renormalization group scheme the critical exponents characterizing the depinning transition are obtained to the first order in ϵ = 4 — D > 0, where D is the interface dimension. The main results were published earlier [T. Nattermann et al., J. Phys. II France 2 (1992) 1483]. Here, we present details of the perturbative calculation and of the derivation of the functional flow Eq. for the random‐force correlator. The fixed point function of the correlator has a cusp singularity which is related to a finite value of the threshold Fc, similar to the mean field theory. We also present extensive numerical simulations and compare them with our analytical results for the critical exponents. For ϵ = 1 the numerical and analytical results deviate from each other by only a few percent. The deviations in lower dimensions ϵ = 2, 3 are larger and suggest that the roughness exponent is somewhat larger than the value ξ = e/3 of an interface in thermal equilibrium.
Exact nuclear level density formula for periodic spectra
Authors: Anzaldo‐Meneses A. 
Published: May 2007

AbstractThe total nuclear level density is obtained for periodic single particle spectra. First, we express the canonical partition function in terms of Jacobi theta functions for degenerated fermion systems. Secondly, we use a relation for the number of representations of an integer number as sums of smaller numbers to find an exact formula for the nuclear level density. The shell structure is incorporated in the result in a simple way. An asymptotic relation can be easily obtained from the exact result and shown to be the well known back‐shifted Bethe‐formula.
Low temperature equilibrium correlation functions in dissipative quantum systems
Authors: Kehrein Stefan K. , Mielke Andreas 
Published: May 2007

AbstractWe introduce a new theoretical approach to dissipative quantum systems. By means of a continuous sequence of infinitesimal unitary transformations, we decouple the small quantum system that one is interested in from its thermodynamically large environment. This yields a trivial final transformed Hamiltonian. Dissipation enters through the observation that generically observables “decay” completely under these unitary transformations, i.e. are completely transformed into other terms. As a nontrivial example the spin‐boson model is discussed in some detail. For the super‐Ohmic bath we obtain a very satisfactory description of short, intermediate and long time scales at small temperatures. This can be tested from the generalized Shiba‐relation that is fulfilled within numerical errors.
Universal elementary constituents of potential transformations shifting waves (qualitative theory)
Authors: Chabanov V. M. , Zakhariev B. N. , Sofianos S. A. 
Published: May 2007

AbstractIt is shown that the potential perturbation that shifts a chosen standing wave in space is a block of potential barrier and well for every wave bump between neighbouring knots. The algorithms shifting the range of the primary localization of a chosen bound state in a potential well of finite width are as well applicable to the scattering functions if states of the continuous spectrum are considered as bound states normalized to unity but distributed on an infinite interval with vanishing density. The potential perturbations of the same type on the half‐axis concentrate the scattering wave at the origin, thus creating a bound state embedded into the continuous spectrum (zero width resonance).
Similarity renormalization of the electron‐phonon coupling
Authors: Mielke Andreas 
Published: May 2007

AbstractWe study the problem of the phonon‐induced electron‐electron interaction in a solid. Starting with a Hamiltonian that contains an electron‐phonon interaction, we perform a similarity renormalization transformation to calculate an effective Hamiltonian. Using this transformation singularities due to degeneracies are avoided explicitly. The effective interactions are calculated to second order in the electronphonon coupling. It is shown that the effective interaction between two electrons forming a Cooper pair is attractive in the whole parameter space. For a simple Einstein model we calculate the renormalization of the electronic energies and the critical temperature of superconductivity.
Uptake Behavior of Embryonic Chick Liver Cells
Authors: Kanai Miharu , Murata Yoshio , Herbert Damon C. , Soji Tsuyoshi 
Published: May 2007

AbstractThe capacity of selective uptake by liver cells, focusing particularly on the parenchymal and perisinusoidal stellate cells during chick liver development (8–18 days of incubation), was ultrastructurally examined after injection of 240‐nm‐diameter lecithin (phosphatidylcholine) ‐coated or noncoated beads into the extraembryonic circulation. Cytoplasmic projections of both cells as well as extrasinusoidal macrophages reached into the sinusoid‐like vascular spaces. The primitive perisinusoidal stellate cells were identified by immunocytochemistry as being rich in desmin‐positive cytoplasmic intermediate filaments. The cells demonstrated selective uptake of noncoated beads by means of their cytoplasmic projections. These findings were significant in the early period of incubation, indicating that the phagocytic activity is a characteristic and transient phenomenon of developmental differentiation. Large numbers of coated and a few noncoated beads penetrated into the perivascular spaces. The parenchymal cells incorporated only the coated beads that passed through the endothelial lining, suggesting that these cells express selective but limited phagocytic capacity against large “foreign” substances even long before their maturation. The cell projections were not engaged in uptake function. Extrasinusoidal macrophages, Kupffer cells, and intraluminal primitive macrophages all took up both beads; however, lecithin coating of the beads clearly suppressed their uptake function. These data suggest that the uptake function of large “foreign” substances appears to be intrinsic to liver cells and lecithin coating would be useful for delivering large substances to parenchymal cells. Anat Rec, 2007. © 2007 Wiley‐Liss, Inc.
On the complexity of Rocchio's similarity‐based relevance feedback algorithm
Authors: Chen Zhixiang , Fu Bin 
Published: May 2007

AbstractRocchio's similarity‐based relevance feedback algorithm, one of the most important query reformation methods in information retrieval, is essentially an adaptive learning algorithm from examples in searching for documents represented by a linear classifier. Despite its popularity in various applications, there is little rigorous analysis of its learning complexity in literature. In this article, the authors prove for the first time that the learning complexity of Rocchio's algorithm is O(d + d2(log d + log n)) over the discretized vector space {0,…, n − 1}d, when the inner product similarity measure is used. The upper bound on the learning complexity for searching for documents represented by a monotone linear classifier $\left( {\overrightarrow q ,0} \right)$ over {0,…, n − 1}d can be improved to, at most, 1 + 2k (n − 1) (log d − log(n − 1)), where k is the number of nonzero components in q. Several lower bounds on the learning complexity are also obtained for Rocchio's algorithm. For example, the authors prove that Rocchio's algorithm has a lower bound $\Omega \left( {\left( {_2^d } \right){\rm{log}}\,n} \right)$ on its learning complexity over the Boolean vector space {0, 1}d.
Kinetics of the helix/coil transition of the collagen‐like peptide (Pro‐Hyp‐Gly)10
Authors: Miles Christopher A. 
Published: May 2007

AbstractThis article measures the rates of folding and unfolding of the collagen‐like peptide (Pro‐Hyp‐Gly)10 over overlapping concentration and temperature ranges. The data allow calculation of the orders of the folding and the unfolding reactions, the effective Arrhenius activation energies, and numerical solution of the differential equation controlling the helix/coil transition during temperature scanning. The resulting predictions of helicity closely followed DSC measurements of the peptide in both up‐ and down‐scanning modes, confirming the validity of the theoretical equations governing the kinetics of the folding/unfolding process. In both up‐ and down‐scanning, three regions were apparent: “quasistatic,” “rate,” and “mixed.” At very low scanning rates, a quasistatic region revealed a broad, short endotherm that was independent of scanning rate, but dependent on concentration and equal to the equilibrium endotherm. At high up‐scanning rates, the “rate region” endotherm was sharp and tall and Tmax increased with scanning rate. In down‐scanning, the “rate peak” was very broad and very short and Tmax decreased with scanning rate. The “mixed region” showed nascent “rate” and nascent “quasistatic” peaks, which were evident in the same up‐scan under certain conditions. Comparison of (Pro‐Hyp‐Gly)10 and (Pro‐Pro‐Gly)10 showed that the higher temperature stability of (Pro‐Hyp‐Gly)10 is due mainly to its slower rate of unfolding and higher activation energy. © 2007 Wiley Periodicals, Inc. Biopolymers 87: 51–67, 2007.This article was originally published online as an accepted preprint. The “Published Online” date corresponds to the preprint version. You can request a copy of the preprint by emailing the Biopolymers editorial office at biopolymers@wiley.com
Comparison of different methods of risk stratification in urgent and emergency surgery
Authors: Neary W D , Prytherch D , Foy C , Heather B P , Earnshaw J J 
Published: May 2007

AbstractBackgroundThe aim was to compare a number of risk scoring systems prospectively in a cohort of patients who underwent non-elective surgery.MethodsThis was a cohort study of 2349 consecutive patients who had urgent or emergency surgery in a district general hospital in the UK. All patients were scored prospectively using the Revised Goldman Cardiac Risk Index (RGCRI), Portsmouth modification of the Physiological and Operative Severity Score for the enUmeration of Mortality and morbidity (P-POSSUM), Surgical Risk Score (SRS) and Biochemistry and Haematology Outcome Models (BHOM). Actual 30-day and 1-year survival rates were compared with the predicted outcomes using receiver–operator characteristic (ROC) curves and Hosmer–Lemeshow analysis.ResultsSome 141 patients (6·0 per cent) died within 30 days of operation. This increased to 254 (10·8 per cent) by 1 year. The area under the ROC curve for death within 30 days was 0·90 for P-POSSUM, 0·85 for SRS, 0·84 for BHOM and 0·73 for RGCRI. Only the first three risk scores were able to discriminate accurately within the groups (area under ROC curve over 0·8), with no significant variation between expected and observed mortality rates confirmed by Hosmer–Lemeshow analysis. Similar results were found for the ability of each score to predict outcome at 1 year.ConclusionP-POSSUM, SRS and BHOM scoring systems were all able to predict outcome after emergency and urgent surgery, but the SRS had the advantage of ease of calculation. BHOM requires only the most commonly available blood test data and the computer holding these data can easily perform the calculation.d.
Chinoliniumverbindungen (II.) Mitteil.): 3‐Alkyl‐6‐carboxy‐chinolinium‐Verbindungen
Authors: Weygand Friedrich , Frank Erwin 
Published: May 2007

AbstractDie kürzlich mitgeteilte Synthese von Chinoliniumverbindungen läßt sich auch mit α‐Methyl‐acroleindibromid und α‐Äthyl‐acrolein‐dibromid durchführen.
Beitrag zur Synthese der Tetrahydroisochinolin‐Alkaloide unter physiologischen Bedingungen
Authors: Kov ÖDÖN , Fodor GÁBor 
Published: May 2007

AbstractNach einer einfachen Darstellungsmethode des Homovanillyl‐ und Homoisovanillylamins wurde die Kondensation des letztgenannten mit Acetaldehyd unter „zellmöglichen”︁ Bedingungen zud,l‐Salsolin durchgeführt. Bei Tyramin, Homoveratrylamin und Homovanillylamin tritt unter denselben Versuchsbedingungen mangels eines nucleophilen Kohlenstoffatoms kein Ringschluß ein.
Zur Kenntnis der Dimethylnaphthaline des Steinkohlenteers
Authors: Kruber Otto , Oberkobusch Rudolf 
Published: May 2007

AbstractIm Steinkohlenteer wurden 1.3‐ und 1.4‐Dimethyl‐naphthalin nachgewiesen. Es wird eine zusammenfassende Darstellung der Gewinnung der einzelnen Isomeren gegeben.
Zur Synthese von Guanin‐[8‐14C]
Authors: Weygand Friedrich , Großkinsky Otto Alfred 
Published: May 2007

AbstractAusgehend von Ba14CO3 wurde Guanin‐[8‐14C] in 70–75‐proz. Ausbeute, bezogen auf Ba14CO3, dargestellt. Die Ausbeute an Aktivität ist nur unwesentlich geringer.
Über Einschlußverbindungen, I. Mitteil.: Additionsverbindungen der Cycloamylosen
Authors: Cramer Friedrich 
Published: May 2007

AbstractEs wurden Einschlußverbindungen von β‐Dextrin (= Cycloheptaamylose) und Desoxycholsäure dargestellt, insbesondere solche mit leicht polarisierbaren und gefärbten Molekülen. Dabei zeigten sich charakteristische Veränderungen der Eigenschaften der eingeschlossenen Moleküle im Sinne einer Lockerung der Elektronensysteme. Die Cyclodextrine bilden auch in Lösung Einschlußverbindungen.
Die Konstitution des Hypericins
Authors: Brockmann Hans , von Falkenhausen Ernst Herbert Frhr. , Neeff Rütger , Dorlars Alfons , Budde Guntmar 
Published: May 2007

AbstractDurch reduzierende Acetylierung des Hypericins wurde eine blaue, kristallisierte Verbindung dargestellt. Es wird gezeigt, daß sie 4.5.7.10.4′.5′.7′‐Heptaacetoxy‐2.2′‐dimethyl‐meso‐naphthodianthren ist und damit der endgültige Beweis für die Konstitution des Hypericins erbracht. Eine Hypothese über die Entstehung des Hypericins in der pflanze wird diskutiert.
Untersuchungen an Steroiden XXXV): Aromatisierung von Steroid‐3‐ketonen der normal‐Reihe zu hetero‐Phenolen
Authors: Inhoffen Hans Herloff , Kölling Georg , Nehring Peter 
Published: May 2007

AbstractDie Aromatisierung der Desoxycholsäure im Ring A wird beschrieben.
Über einige Derivate des Nickel‐bicarbonates
Authors: Klages Friedrich , Heinle Rudolf 
Published: May 2007

AbstractEs werden die Darstellung und Eigenschaften komplexer Bicarbonato‐pyridin‐nickel‐Verbindungen beschrieben, die als Derivate des in freier Form unbeständigen Nickelbicarbonates von Interesse sind.