bluuebunny/crossref_metadata_2025_split huggingface dataset:
Observation of magnetic field-induced contraction of fission yeast cells using optical projection microscopy
Authors: Yang Xi , Beckwith Andrew , Miller John , Wood Lowell 
Published: August 2006

AbstractThe charges in live cells interact with or produce electric fields, which results in enormous dielectric responses, flexoelectricity, and related phenomena. Here we report on a contraction of Schizosaccharomyces pombe (fission yeast) cells induced by magnetic fields, as observed using a phase-sensitive projection imaging technique. Unlike electric fields, magnetic fields only act on moving charges. The observed behavior is therefore quite remarkable, and may result from a contractile Lorentz force acting on diamagnetic screening currents. This would indicate extremely high intracellular charge mobilities. Besides, we observed a large electro-optic response from fission yeast cells.
Covering group and graph of discretized volumes
Authors: Makai Mihály , Orechwa Yuri 
Published: August 2006

AbstractWe consider a discretized volume V consisting of finite, congruent and attached copies of a tile t. We find a group L V the orbit of which, when applied to t, is just V. We show the connection between the structural matrixQ in the formal solution of a boundary value problem formulated for volume V and the so called auxiliary matrix of the graph Γv associated with V. We show boundary value problems to be isomorphic if the graphs associated with the volumes are isomorphic, or, if the covering groups are Sunada pairs.
Simulation model for shapiro time delay and light deflection experiments
Authors: Biswas Abhijit , Mani Krishnan 
Published: August 2006

AbstractThe time delay experiment proposed by I.I. Shapiro in 1964 and conducted in the seventies was the most precise experiment of general relativity until that time. Further experimentation has improved the accuracy level of both the time delay and the light deflection experiments. A simulation model is proposed that involves only a simple mass and time transformation factor involving velocity of light. The light deflection and the time delay experiments are numerically simulated using this model that does not use the general relativistic equations. The computed values presented in this paper compare well with recent levels of accuracy of their respective experimental results.
XPS Study of group IA carbonates
Authors: Shchukarev A. , Korolkov D. 
Published: August 2006

Abstract
The results of systematic XPS measurements of all alkali metal carbonates (Li, Na, K, Rb and Cs) are presented. The first set of experiments was performed with “as received” commercial carbonate powders under liquid nitrogen conditions using a precooling procedure. A second set of experiments was performed under similar experimental conditions after a preliminary grinding (mechanical activation) of the carbonates. In addition, Na2CO3
*1H2O, NaHCO3 and KHCO3 powders were studied. It was found that sample pre-cooling allows distinction between hydrocarbonates and carbonate hydrates. Storage in air leads to formation of hydrocarbonates at the surface of Li2CO3 and Na2CO3. This phenomenon being more pronounced in the former. In contrast, K2CO3 forms a hydrate with one H2O molecule. Rb2CO3 and Cs2CO3 have hydrocarbonates as well as hydrates at the surface and this is more pronounced for Cs2CO3. Grinding of the carbonates results in the formation of hydrocarbonates at the surface, the tendency to do so was found to increase down the group IA, namely, K<Rb≪Cs. For the most part, the hydrocarbonates formed were unstable in vacuum even under liquid nitrogen conditions. Chemical trends in C 1s and O 1s binding energies in carbonates and hydrocarbonates of the Group IA are discussed and related to the nature of the anion and alkali cation.
Chemometric study of soil analysis data
Authors: Spanos Th. , Simeonov V. , Tsakovski S. , Thiokas D. 
Published: August 2006

Abstract
The present paper deals with chemometric interpretation of soil analysis data collected from 31 sampling sites in the region of Kavala and Drama, Northern Greece. The determination of 16 different chemical and physicochemical characteristics is principally needed for prognosis of the land treatment and fertilizing. The study carried out indicates that the application of multivariate statistical approaches could reveal new and specific information about sampling sites. It has been found that they could be divided into four general patterns: pattern 1 contains dominantly inorganic and alkaline soil samples from semi-mountainous regions in close proximity to the seacoast; pattern 2 indicates the same soil sample type and regional location as pattern 1 but is far from the coastal line; pattern 3 includes samples from sites from the plains with organic and alkaline soils with close proximity to the coast; pattern 4 resembles pattern 3 as soil type but involves samples from sites far from the shore. Further, six latent factors were identified, conditionally named “structural”, “acidic”, “nutritional”, “salt”, “microcomponents” and “organic”. Finally, an apportioning procedure was carried out to find the source contributions in the measured analytical values. In this way the routine estimation of the soil quality could be improved.
Multilayer mirror systems to form hard X-ray beams
Authors: Akhsakhalyan Anton , Akhsakhlyan Aram , Kharitonov Alexander , Kluenkov Eugenie , Murav’ev Vladimir , Salashchenko Nikolay 
Published: August 2006

Abstract
This paper is an overview of the research activities carried out in the past five years at the Institute for Physics of Microstructures RAS and “X-ray” Company towards the manufacture of multilayer mirror systems capable of forming X-ray beams in the subnanometer range of wavelengths. The systems fabrication technology is presented, including techniques for producing supersmooth surfaces of specified shape, methods of graded multilayer structure deposition on such surfaces, and the principles of designing optimal mirror parameters. The characteristics of a quadrelliptical reflector—a novel high light-gathering power four-corner focusing system—are reported.
The Hurwitz determinants and the signatures of irreducible representations of simple real Lie algebras
Authors: Rudy Alexander 
Published: August 2006

Abstract
The paper deals with the real classical Lie algebras and their finite dimensional irreducible representations. Signature formulae for Hermitian forms invariant relative to these representations are considered. It is possible to associate with the irreducible representation a Hurwitz matrix of special kind. So the calculation of the signatures is reduced to the calculation of Hurwitz determinants. Hence it is possible to use the Routh algorithm for the calculation.
Bivariant Chern classes for morphisms with nonsingular target varieties
Authors: Yokura Shoji 
Published: August 2006

Abstract
W. Fulton and R. MacPherson posed the problem of unique existence of a bivariant Chern class—a Grothendieck transformation from the bivariant theory F of constructible functions to the bivariant homology theory H. J.-P. Brasselet proved the existence of a bivariant Chern class in the category of embeddable analytic varieties with cellular morphisms. In general however, the problem of uniqueness is still unresolved. In this paper we show that for morphisms having nonsingular target varieties there exists another bivariant theory
$$\tilde {\mathbb{F}}$$
of constructible functions and a unique bivariant Chern class γ:
$$\tilde {\mathbb{F}} \to {\mathbb{H}}$$
.
Quaternionic geometry of matroids
Authors: Hausel Tamás 
Published: August 2006

Abstract
Building on a recent paper [8], here we argue that the combinatorics of matroids are intimately related to the geometry and topology of toric hyperkähler varieties. We show that just like toric varieties occupy a central role in Stanley’s proof for the necessity of McMullen’s conjecture (or g-inequalities) about the classification of face vectors of simplicial polytopes, the topology of toric hyperkähler varieties leads to new restrictions on face vectors of matroid complexes. Namely in this paper we will give two proofs that the injectivity part of the Hard Lefschetz theorem survives for toric hyperkähler varieties. We explain how this implies the g-inequalities for rationally representable matroids. We show how the geometrical intuition in the first proof, coupled with results of Chari [3], leads to a proof of the g-inequalities for general matroid complexes, which is a recent result of Swartz [20]. The geometrical idea in the second proof will show that a pure O-sequence should satisfy the g-inequalities, thus showing that our result is in fact a consequence of a long-standing conjecture of Stanley.
Magnetic field and currents in HTSC films
Authors: Gaikovich K. , Nozdrin Yu. , Zhilin A. 
Published: August 2006

Abstract
Magnetic field measurements above type-II superconductor films in a remanent magnetization state have been used to determine two dimensional surface current distributions. Using the Biot-Savart law for the surface current density, integral equations (of 2-D convolution type) for two components of current have been obtained. These equations have been solved by employing Tikhonov's method of generalized discrepancy, and the surface current pattern in superconductors as well as the magnetic field distribution on the film surface have been obtained. Current peculiarities related to various kinds of inhomogeneities, specific character of the film form, and a laser pulse effect have been observed. In particular, it was discovered that a laser pulse can signficantly redistribute the film currents without changing the total number of current vortices in the film.
Electron spectral density of the half-filled Hubbard model in the atomic limit at finite temperature
Authors: Ovchinnikov Sergei , Shneyder Elena 
Published: August 2006

Abstract
We have calculated the spectral function and density of states of halffilled two-dimensional Hubbard model in the Hubbard-I approximation assuming an antiferromagnetic long range order at low temperature and compared results to the QMC data. It occurs that calculated functions are in a qualitative agreement with the QMC one. We have also shown that Neel ordered state dispersion has the similar form to the spin density wave one.
Application of the Volterra filter in experimental diffraction data processing
Authors: Jurečka Stanislav , Jurečková Mária 
Published: August 2006

Abstract
The effective signal in x-ray diffraction analysis of material properties often contains high frequency (noise) and low frequency (trend) components as additive parts. It is necessary to extract the effective signal from the noise to ensure high quality of signal processing. Digital filters of Volterra type are proposed for filtering purposes and a comparison of Volterra filtration implemented on x-ray diffraction data versus results from a set of other digital filters is given.
Steady-state analytical solutions for the lattice boltzmann equation
Authors: Házi Gábor 
Published: August 2006

Abstract
A general class of analytical solutions of the lattice Boltzmann equation is derived for two-dimensional, steady-state unidirectional flows. A subset of the solutions that verifies the corresponding Navier-Stokes equations is given. It is pointed out that this class includes, e.g., the Couette and the Poiseuille flow but not, e.g., the basic Kolmogorov flow. For steady-state non-unidirectional flows, first and second order solutions of the lattice Boltzmann equation are derived. Practical consequences of the analysis are mentioned. Differences between the technique applied here and those used in some earlier works are emphasized.
Formation and dynamics of Saturn and its disk simulated by using a new N-body model
Authors: Pavlov A. , Pavlova Y. 
Published: August 2006

AbstractThe formation of Saturn and its disk is simulated using a new N-body self-gravitational model. It is demonstrated that the formation of the disk and the planet is the result of gravitational contraction of a slowly rotated particle cloud that have a shape of slightly deformed sphere. The sphere was flattened by a coefficient of 0.8 along the axis of rotation. During the gravitational contraction, the major part of the cloud transformed into a planet and a minor part transformed into a disk. The thin structured disk is a result of the electromagnetic interaction in which the magnetic forces acting on charged particles of the cloud originate in the core of the planet. The simulation program gives such parameters of Saturn as the escape velocity of about 35 km/s at the surface, density, rotational velocities of the rings and temperature distribution.
Positron annihilation study for cadmium (electronic structure and enhancement effect)
Authors: Hamid A. 
Published: August 2006

AbstractThe three dimensional electron density in momentum space ρ(p) and in wave vector space n(k) was reconstructed for cadmium (Cd). The measurements were performed using the two dimensional angular correlation of annihilation radiation (2D-ACAR) technique. Enhanced contributions in the spectra were observed around 5.5 mrad, discussed in terms of a Kahana-like enhancement effect. From another viewpoint, Fermi radii were analyzed in the (λM K), (ALM) and (AHK) planes, and they showed a maximum deviation of about 4% from the free electron Fermi radius. Moreover, comparisons to a radio-frequency size effect (RFSE) experiment and theoretical band structure calculations (using augmented plane wave (APW), linear combination of atomic orbital (LCAO) and linear muffin tin orbital (LMTO) methods) were examined. The results showed a qualitative agreement with both APW and LCAO calculations. However, a favorable agreement with the APW method was determined via Fermi surface dimensions. The differences of bands' occupation of n(k) between the current work and the APW method were argued in view of positron wave function in Cd.
Rank 4 vector bundles on the quintic threefold
Authors: Madonna Carlo 
Published: August 2006

Abstract
By the results of the author and Chiantini in [3], on a general quintic threefold X⊂P
4 the minimum integer p for which there exists a positive dimensional family of irreducible rank p vector bundles on X without intermediate cohomology is at least three. In this paper we show that p≤4, by constructing series of positive dimensional families of rank 4 vector bundles on X without intermediate cohomology. The general member of such family is an indecomposable bundle from the extension class Ext
1 (E, F), for a suitable choice of the rank 2 ACM bundles E and F on X. The existence of such bundles of rank p=3 remains under question.
Generalized interval exchanges and the 2–3 conjecture
Authors: Friedland Shmuel , Weiss Benjamin 
Published: August 2006

Abstract
We introduce the notion of a generalized interval exchange
$$\phi _\mathcal{A} $$
induced by a measurable k-partition
$$\mathcal{A} = \left\{ {A_1 ,...,A_k } \right\}$$
of [0,1).
$$\phi _\mathcal{A} $$
can be viewed as the corresponding restriction of a nondecreasing function
$$f_\mathcal{A} $$
on ℝ with
$$f_\mathcal{A} (0) = 0, f_\mathcal{A} (k) = 1$$
. A is called λ-dense if λ(A
i∩(a, b))>0 for each i and any 0≤ a< b≤1. We show that the 2–3 Furstenberg conjecture is invalid if and only if there are 2 and 3 λ-dense partitions A and B of [0,1), such that
$$f_\mathcal{A} \circ f_\mathcal{B} = f_\mathcal{B} \circ f_\mathcal{A} $$
. We give necessary and sufficient conditions for this equality to hold. We show that for each integer m≥2, such that 3∤2m+1, there exist 2 and 3 non λ-dense partitions A and B of [0,1), corresponding to the interval exchanges on 2m intervals, for which
$$f_\mathcal{A} $$
and
$$f_\mathcal{B} $$
commute.
On the riemann zeta-function and the divisor problem
Authors: Ivić Aleksandar 
Published: August 2006

Abstract
Let Δ(x) denote the error term in the Dirichlet divisor problem, and E(T) the error term in the asymptotic formula for the mean square of
$$\left| {\varsigma \left( {\tfrac{1}{2} + it} \right)} \right|$$
. If
$$E^* \left( t \right) = E\left( t \right) - 2\pi \Delta ^* \left( {t / 2\pi } \right)$$
with
$$\Delta ^* \left( x \right) = - \Delta \left( x \right) + 2\Delta \left( {2x} \right) - \tfrac{1}{2}\Delta \left( {4x} \right)$$
, then we obtain
$$\int_0^T {\left( {E^* \left( t \right)} \right)^4 dt \ll _e T^{16/9 + \varepsilon } } $$
. We also show how our method of proof yields the bound
$$\sum\limits_{r = 1}^R {\left( {\int_{tr - G}^{tr + G} {\left| {\varsigma \left( {\tfrac{1}{2} + it} \right)} \right|^2 dt} } \right)^4 \ll _e T^{2 + e} G^{ - 2} + RG^4 T^\varepsilon } $$
, where T
1/5+ε≤G≪T, T<t
1<...<t
R≤2T, t
r
+1−t
r≥5G (r=1, ..., R−1).
Nondegenerate cohomology pairing for transitive Lie algebroids, characterization
Authors: Kubarski Jan , Mishchenko Alexandr 
Published: August 2006

Abstract
The Evens-Lu-Weinstein representation (Q
A, D) for a Lie algebroid A on a manifold M is studied in the transitive case. To consider at the same time non-oriented manifolds as well, this representation is slightly modified to (Q
Aor, Dor) by tensoring by orientation flat line bundle, Q
Aor=QA⊗or (M) and D
or=D⊗∂Aor. It is shown that the induced cohomology pairing is nondegenerate and that the representation (Q
Aor, Dor) is the unique (up to isomorphy) line representation for which the top group of compactly supported cohomology is nontrivial. In the case of trivial Lie algebroid A=TM the theorem reduce to the following: the orientation flat bundle (or (M), ∂Aor) is the unique (up to isomorphy) flat line bundle (ξ, ∇) for which the twisted de Rham complex of compactly supported differential forms on M with values in ξ possesses the nontrivial cohomology group in the top dimension. Finally it is obtained the characterization of transitive Lie algebroids for which the Lie algebroid cohomology with trivial coefficients (or with coefficients in the orientation flat line bundle) gives Poincaré duality. In proofs of these theorems for Lie algebroids it is used the Hochschild-Serre spectral sequence and it is shown the general fact concerning pairings between graded filtered differential ℝ-vector spaces: assuming that the second terms live in the finite rectangular, nondegeneration of the pairing for the second terms (which can be infinite dimensional) implies the same for cohomology spaces.
A geometric theory of harmonic and semi-conformal maps
Authors: Kock Anders 
Published: August 2006

Abstract
We describe for any Riemannian manifold M a certain scheme M
L, lying in between the first and second neighbourhood of the diagonal of M. Semi-conformal maps between Riemannian manifolds are then analyzed as those maps that preserve M
L; harmonic maps are analyzed as those that preserve the (Levi-Civita-) mirror image formation inside M
L.
Determination of inorganic arsenic species As(III) and As(V) by high performance liquid chromatography with hydride generation atomic absorption spectrometry detection
Authors: Niedzielski P. , Siepak M. , Novotny K. 
Published: August 2006

Abstract
The paper presents the principles and advantages of a technique combining high performance liquid chromatography and hydride generation atomic absorption spectrometry (HPLC-HGAAS) applied to speciation analysis of inorganic species of arsenic As(III) and As(V) in ground water samples. With separation of the arsenic species on an ion-exchange column in the chromatographic system and their detection by the hydride generation atomic absorption spectrometry, the separation of the analytical signals of the arsenic species was excellent at the limits of determination of 1.5 ng/ml As(III) and 2.2 ng/ml As(V) and RSD of 4.3% and 7.8% for the concentration of 25 ng/ml. The hyphenated technique has been applied for determination of arsenic in polluted ground water in the course of the study on migration of micropollutants. For total arsenic concentration two independent methods: HGICP-OES and HGAAS were used for comparison of results of real samples analysis.
Evaluation of 13C NMR spectra of cyclopropenyl and cyclopropyl acetylenes by theoretical calculations
Authors: Ananikov Valentine 
Published: August 2006

Abstract
A convenient methodology was developed for a very accurate calculation of 13C NMR chemical shifts of the title compounds. GIAO calculations with density functional methods (B3LYP, B3PW91, PBE1PBE) and 6-311+G(2d,p) basis set predict experimental chemical shifts of 3-ethynylcyclopropene (1), 1-ethynylcyclopropane (2) and 1,1-diethynylcyclopropane (3) with high accuracy of 1–2 ppm. The present article describes in detail the effect of geometry choice, density functional method, basis set and effect of solvent on the accuracy of GIAO calculations of 13C NMR chemical shifts. In addition, the particular dependencies of 13C chemical shifts on the geometry of cyclopropane ring were investigated.
Synthesis of aldehydes and ketones by the dehydrogenation of alcohols in the presence of a Raney nickel/aluminium isopropoxide/alumina catalyst
Authors: Tarta Ilie , Silberg Ioan , Vlassa Mircea , Oprean Ioan 
Published: August 2006

Abstract
The synthesis of aldehydes and ketones by the dehydrogenation of allylic and secondary alcohols using a Raney-Ni-Al(i-OPr)3-Al2O3 catalyst without hydrogen acceptors is presented.
The synthesis and the structure elucidation of N,O-diacetyl derivative of cyclic 3-hydroxymelatonin
Authors: Siwicka Aleksandra , Reiter Russel , Tian Dun , Wojtasiewicz Krystyna , Leniewski Andrezej , Maurin Jan , Błachut Dariusz , Czarnocki Zbigniew 
Published: August 2006

AbstractMelatonin was subjected to an oxidation to give 3-hydroxymelatonin. All spectroscopic data for this compound were collected. Ab initio calculations for both possible configurations were performed. X-ray data on N,O-diacetyl derivative of 3-hydroxymelatonin allowed the unambigous structure determination.
Crystal structure and spectral characterization of dimethylthallium (III) complexes with 2-mercaptonicotinic acid and esters
Authors: Toma Monica , Sánchez Agustín , García-Tasende María , Casas José , Sordo José , Castellano Eduardo , Ellena Javier 
Published: August 2006

AbstractSynthesis, spectral properties and crystal structure of dimethylthallium(III) complexes with 2-mercaptonicotinic acid (2mna), 2-mercapto-methyl-nicotinate (2mmn), 2-mercapto-ethyl-nicotinate (2men) and 2-mercapto-isopropyl-nicotinate (2min) are reported. The compounds were characterized using IR, multinuclear NMR (1H,13C,205Tl) and mass spectrometry (electrospray, ES-API). The molecular structures of [TlMe2(2mna)]·H2O, (1), [TlMe2(2mmn)], (2), [TlMe2(2men)], (3) and [TlMe2(2min)], (4) were determined by the single-crystal X-ray diffraction. In 1, the monodeprotonate O,S-bidentate ligand chelates one dimethylthallium (III) unit and simultaneously bridges (O and S) between two of these organometallic units. The Tl-O1′ and Tl-S″ interactions are leading to polymeric chain linked in a three-dimensional network by the hydrogen bonds formed between the water molecule and the oxygen O (2) atom of the acid. The thallium atom is in a distorted octahedral environment with a [TlC2O2S2] kernel. Compounds 2, 3 and 4 are similar, in all the cases already mentioned the ligand is NH deprotonated and is strongly coordinated to two dimethylthallium (III) units through the N and S atoms. Two additional weak interactions with the O and S atoms lead to a [TlC2NOS2] kernel for the metal atom, in which the coordination polyhedron is a very distorted octahedron with the methyl groups occupying the apical positions.