bluuebunny/crossref_metadata_2025 huggingface dataset:
Gas Diffusion-Flow Injection Determination of Free and Total Sulfur Dioxide in Wines by Conductometry
Authors: Kubáň Petr , Janoš Pavel , Kubáň Vlastimil
Published: July 2002

Sensitive flow injection analysis methods for the determination of free and total sulfur dioxide in wines are presented. The bound S(IV) was liberated by alkaline hydrolysis with 4 mol/l NaOH. All forms of S(IV) were liberated from the sample zone by sulfuric acid and subsequently transported through a microporous PVDF membrane. The penetrated gases were collected in water for preselected period and determined by conductometry with detection limit 1 mg/l and relative standard deviations 0.8 and 0.6% at 10 and 150 mg/l (n = 10) for free and total S(IV), respectively. The results are comparable with those obtained by standard titrimetric procedures with visual (Czech State Standard) and/or potentiometric indication.
On Temperature Dependence of Excess Gibbs Energy
Authors: Malijevská Ivona , Malijevský Anatol
Published: July 2002

Temperature dependence of GE is discussed for three widely used equations linear and nonlinear in parameters. It is shown that the Wilson equation predicts always positive excess heat capacity regardless of values of its parameters. Several temperature modifications of the Redlich-Kister, Wilson and NRTL equations are discussed with respect to the sign of the excess Gibbs energy, excess enthalpy and excess heat capacity.
Interdigitated Array Diffusion Layer Titration of Dithiocarbamates with Electrogenerated Hypobromite
Authors: Tomčík Peter , Bustin Dušan
Published: July 2002

A simple but sensitive technique was developed for determination of dithiocarbamates. The proposed method is based on its oxidation with hypobromite under the formation of sulfate. The oxidation proceeds only in the close vicinity of interdigitated array microelectrode (IDA), the segments of which were used as working and indicator electrodes. Hypobromite was formed by disproportionation of galvanostatically generated bromine (from bromide) in weakly alkaline solution on one segment of IDA (generator). The unreacted flux of hypobromite was amperometrically detected on the second segment (collector-indicator). The hypobromite flux is influenced by dithiocarbamates present in solution, causing changes in the collector versus generator current plot (titration curve) which can be quantitatively evaluated. The sensitivity of the method is 7 795 l mol-1 μA and detection limit estimated according to the 3s criterion is 2.2 · 10-6 mol l-1. The technique was used in analysis of real samples, such as in determination of a pesticide residues in cucumber leaves.
Biotransformation of Benfluron by Rat Hepatic Cytochrome P450. Identification of Individual CYP-Enzymes Involved in Biotransformation of Benfluron, Prospective Antineoplastic Based on Benzo[c]fluorene
Authors: Hrubý Kamil , Anzenbacherová Eva , Anzenbacher Pavel , Nobilis Milan
Published: July 2002

Benfluron, 5-[2-(dimethylamino)ethoxy]-7H-benzo[c]fluoren-7-one hydrochloride, a prospective antineoplastic agent, is metabolised by cytochromes P450 toN-demethyl and 9-hydroxy derivatives. To prove the participation of individual cytochrome P450 isoforms in formation of these metabolites, selective induction of cytochromes P450, inhibition of benfluron biotransformation using inhibitors specific for individual cytochromes P450, and inhibition by benfluron of "marker" enzyme activities characteristic of certain cytochromes P450 were used.N-Demethylbenfluron appears to be formed mainly by the cytochromes P450 of the 3A, 2B and 2C subfamilies with possible participation of the isoform 2E1; 9-hydroxybenfluron is formed with participation of cytochromes P450 belonging to 1A, and most probably to 3A and 2E1 enzymes. The fact that benfluron is in this respect a relatively promiscuous substrate may be an advantage because its metabolism should not be influenced by the absence or low activity of some cytochrome P450 isoforms and by possible drug interactions.
Surface and Interfacial Tensions Along the Binodal Curve in the tert-Butyl Methyl Ether-Water-Alcohol Ternary Systems at 25 °C
Authors: Bartovská Lidmila , Čechová Markéta , Matouš Jaroslav , Novák Josef P.
Published: July 2002

The surface tensions, interfacial tensions, and densities of conjugate solutions of compositions lying in the miscibility gap were measured for three ternary systems, viz. tert-butyl methyl ether-water-ethanol, tert-butyl methyl ether-water-tert-butyl alcohol, and tert-butyl methyl ether-water-butan-1-ol, at 25 °C.
The "Presodium" Hydrogen Evolution at the Dropping Mercury Electrode Catalysed by Simple Cysteine Peptides
Authors: Mader Pavel , Veselá Věra , Dorčák Vlastimil , Heyrovský Michael
Published: July 2002

"Presodium" catalytic currents at dropping mercury electrode of cysteine, cysteinylglycine, γ-glutamylcysteine and reduced glutathione were systematically studied in weakly alkaline solutions. They consist in shifts to positive potentials of current due to reduction of the blank solution, and, under some conditions, also in formation of "catalytic prewaves". The two cases have been qualitatively interpreted as based on a suggested common mechanism, differing by the occurrence of weak catalyst adsorption in the prewave case. The catalytic activity depends on the catalyst itself (concentration, structure, conformation at the electrode, partial protonation/ionisation, partial hydrophobic/hydrophilic character) as well as on the solution (pH, ionic strength, nature and concentration of components).
Synthesis of 2,24-Diepicastasterone and 3,24-Diepicastasterone as Potential Brassinosteroid Metabolites of the Cockroach Periplaneta americana
Authors: Voigt Brunhilde , Porzel Andrea , Adam Günter , Golsch Dieter , Adam Waldemar , Wagner Christoph , Merzweiler Kurt
Published: July 2002

Investigations of the metabolic conversion of the phytohormone 24-epicastasterone (1) in the cockroach Periplaneta americana (L.) required the synthesis of 2,24-diepicastasterone (4), 3,24-diepicastasterone (7b) and 2-dehydro-3,24-diepicastasterone (9) as reference standards. 2,24-Diepicastasterone (4) was synthesized from 2α,3α-epoxy derivative 2 as well as from the 2β,3β-epoxy-22,23-diol 3 by acid-catalyzed water addition to the epoxy function leading to the desired 2β,3α-trans functionality. 3,24-Diepicastasterone (7b) was prepared by NaBH4-reduction of the 3-oxo derivative 6. Upon deprotection conditions from the ketol acetonides 6 and 8 in both cases 2-dehydro-3,24-diepicastasterone (9) was obtained. The structure of 2,24-diepicastasterone (4) was confirmed by X-ray analysis.
On the Structure of Lead(II) Complexes in Aqueous Solutions. III. Hexanuclear Clusters
Authors: Breza Martin , Manová Alena
Published: July 2002

Optimum geometries based on experimental structures and corresponding electronic structures of [Pb6(μ3-OH)8]4+ and [Pb6O(μ3-OH)6]4+ clusters as well as of their hydrated [Pb6(μ3-OH)8(H2O)6]4+ and [Pb6O(μ3-OH)6(H2O)6]4+ analogues are investigated using the semiempirical MNDO method of quantum chemistry. Direct Pb-Pb and O-O bonds are vanishing in the systems under study. Small differences in interatomic Pb-Pb and Pb-O distances between these clusters indicate that they cannot be distinguished by recent experimental techniques in solution. Both the mentioned structures are stable and might coexist in solution.
Direct Preparation of N-(Alk-1-en-1-yl)carbamates from Cyclic Ketones and Unsubstituted Carbamates
Authors: Dupau Philippe , Hay Anne-Emmanuelle , Alameda Angulo Célia , Dixneuf Pierre H. , Bruneau Christian
Published: July 2002

N-(Alk-1-en-1-yl)carbamates bearing an endocyclic carbon-carbon double bond have been prepared by the reaction of unsubstituted carbamates with tetrahydronaphthalen-2-one and chroman-2-one derivatives in the presence of a catalytic amount of 4-methylbenzene-1-sulfonic acid.
Cardenamides from Cardenolides: Cardiac and Anticancer Activities
Authors: Megges Rudolf , Weiland Jürgen , Schön Rudolf , Repke Heinrich , Repke Kurt R. H.
Published: July 2002

Two ways are shown to transform cardioactive cardenolides into cardenamides [17β-(5-oxo-2,5-dihydropyrrol-3-yl)-5β,14β-androstane derivatives], and their derivatives by replacement of their ring oxygen by N-R. Cardioactivity is strongly decreased by this transformation. The comparatively easily accessible 21-oxocardenamides [17β-(2-maleimidyl)steroids] are strongly thiol reactive and show remarkable anticancer activity.
Rupture of the axillary (circumflex) nerve and artery in a champion jockey: Figure 1
Authors: Patel J , Turner M , Birch R , McCrory P
Published: July 2002

Rupture of the circumflex artery and nerve, without fracture or dislocation, is a rare traumatic event. Such a case is reported in a champion flat jockey who sustained blunt trauma to the shoulder after a fall during a race; the literature is also reviewed. At urgent surgical exploration, the axillary artery and nerve were repaired. The patient subsequently successfully returned to professional riding. This case highlights the difficulties in diagnosis and management.
Haemodynamics during a complete exercise induced atrioventricular block
Authors: Crisafulli A , Melis F , Lai A C , Orrù V , Lai C , Concu A
Published: July 2002

The case is reported of an athlete who, during an exercise test, had a complete atrioventricular block without symptoms of cardiac output failure. Heart rate, stroke index, cardiac index, and myocardial contractility were monitored during the episode by an impedance cardiograph. The most important findings of this report are the continuous increase in stroke index, which compensated for the lack of heart rate response, and the normal cardiac index values achieved during the exercise. This stroke index response was mainly due to an increase in myocardial contractility.
Day-case percutaneous endoscopic gastrostomy: a viable proposition?
Authors: Mandal A , Steel A , Davidson A R , Ashby C
Published: July 2002

The aim of our study was to evaluate the success rate, complications, and long term outcomes following day-case percutaneous endoscopic gastrostomy (PEG). This retrospective study was carried out in a 650-bed District General hospital in Northamptonshire, UK. Thirty-six patients, aged 28–90 years, were included in the study, 21 males (58%) and 15 females (42%). Indications for PEG insertion included head and neck cancer, dysphagia as a result of primary disease, and AIDS-related malnutrition. Data were collected from the medical and dietetic records. The PEG procedure was successful in 33 patients (92%). In 32 cases (97%) the patient was discharged home. Twenty five of the patients (76%) suffered no complications whilst seven (21%) suffered complications within a month of the procedure. No patient required further surgical intervention. Five patients (15%) died of their primary disease within a month of the procedure. Patients had had their PEG tubes in situ for up to 2.5 years at the end of data collection. We conclude that PEG can be performed as a day-case procedure in stable patients with no increase in complication rate, morbidity, or mortality.
Aortic aneurysm and dissection are not associated with an increased risk for giant cell arteritis/ polymyalgia rheumatica
Authors: Ehrenfeld Michael , Bitzur Rafael , Schneiderman Jacob , Smolinsky Aram , Sidi Yechezkel , Gur Hanan
Published: July 2002

It has recently been claimed that giant cell arteritis (GCA) is associated with a markedly increased risk of aortic aneurysm formation or rupture. In the present study, the opposite approach was taken, by looking for the incidence of GCA and polymyalgia rheumatica (PMR) in patients with aortic aneurysm, aortic dissection, or both (AA/D). The records of 315 consecutive patients admitted with the diagnosis of AA/D were reviewed. In addition, follow up information was obtained in 82 patients by examination in the outpatient clinic. After careful examination and assessment of clinical and laboratory data, it was found that none of the 82 patients who survived hospitalisation and were available for examination had GCA or PMR. Moreover, review of the retrospective data available from hospital records of the total consecutive 315 patients with AA/D failed to find any patient with a diagnosis of GCA/PMR. In conclusion, the present study did not find an increased prevalence of GCA/PMR among a cohort of Israeli patients with AA/D. Therefore, it is suggested that a thorough investigation aiming to diagnose GCA/PMR is not cost effective in most of the elderly patients presenting with AA/D.
Primary hypothyroidism masquerading as hepatic encephalopathy: case report and review of the literature
Authors: Thobe Nicole , Pilger Pamela , Jones Michael P
Published: July 2002

A 74 year old woman with hepatitis C of long duration was admitted to hospital in hyperammonaemic coma. Despite aggressive treatment of hepatic encephalopathy, there was no clinical improvement. As part of her evaluation for other causes of altered mental status, she was found to be profoundly hypothyroid. Treatment with thyroid replacement hormone was accompanied by prompt normalisation of her mental status and hyperammonaemia. Hypothyroidism may exacerbate hyperammonaemia and portosystemic encephalopathy in patients with otherwise well compensated liver disease. Hyopthyroidism should be considered in the differential diagnosis of encephalopathy in patients with liver disease.
Amyloidosis
Authors: Khan M F , Falk R H
Published: July 2002

Amyloidosis is not a single disease but a series of diseases in which there is extracellular deposition of a protein which, although it may be derived from different and unrelated sources, folds into a β pleated sheet.

There have recently been significant advances in elucidating the pathogenesis and in the treatment of this group of disorders. By identifying the source of precursor protein, treatment is aimed at eliminating or reducing the extent of deposition and is tailored for each patient.

Early diagnosis is required for the optimal effect of treatment on patient survival and quality of life. An increased awareness among physicians of the spectrum of the disease and tools to aid its diagnosis is of increasing importance.
Mycoplasma pneumoniae induced popliteal artery thrombosis treated with urokinase
Authors: Joo C U , Kim J S , Han Y M
Published: July 2002

A 5 year old boy with serological and clinical evidence of Mycoplasma pneumoniae infection, which was complicated by popliteal artery thrombosis, is described. Intra-arterial urokinase, in conjunction with medical treatment, resulted in clinical recovery and angiographic resolution of the thrombus. The variety of extrapulmonary complications associated with the M pneumoniae infections continues to broaden. Thrombolytic therapies should be considered when similar clinical circumstances arise.
Necrotising fasciitis in a patient receiving infliximab for rheumatoid arthritis
Authors: Chan A T Y , Cleeve V , Daymond T J
Published: July 2002

A case of necrotising fasciitis in a patient receiving infliximab, an antitumour necrosis factor alpha (TNF-α) agent for rheumatoid arthritis, is presented. A widespread confluent, erythematous, pustular skin rash was the presenting sign. There was no fever throughout this admission. β-Haemolytic group A streptococcus was isolated from blood cultures and skin swabs. The adductor muscles and fascia around the site of a previous hip arthroplasty were necrotic on exploration. The case highlights the risk of severe sepsis in patients on anti-TNF-α treatment.
Incorporating Allee effects in fish stockrecruitment models and applications for determining reference points
Authors: Chen D G , Irvine J R , Cass A J
Published: July 2002

A new type of stockrecruitment model is examined that incorporates Allee effects, which may occur when fish populations are small. The model is a natural extension of traditional models, which only incorporate the negative effects of increasing density on fecundity and (or) survival. Because the new model is intrinsically nonlinear and because of convergence problems at local optima, we use a maximum likelihood approach with a global genetic search algorithm to estimate model parameters. Parameter uncertainty is obtained from the inverse of the Fisher information matrix. Based on this new model, an extinction probability curve is developed using the parameter defining the Allee effects. This curve can readily be used to calculate the theoretical probability of extinction for a single brood line in one generation for any particular spawner number or biomass. Alternatively, because managers may wish to assign reference points corresponding to particular extinction probabilities, spawner numbers can be determined for these reference points. Two Pacific salmon populations, North Thompson coho (Oncorhynchus kisutch) and Chilko sockeye (O. nerka), are used to demonstrate the approach. It is found that the Allee effect parameter is statistically significant for the Thompson coho, but not for Chilko sockeye.
Comparative mapping of Homo sapiens chromosome 4 (HSA4) and Sus scrofa chromosome 8 (SSC8) using orthologous genes representing different cytogenetic bands as landmarks
Authors: Jiang Zhihua , He Hong , Hamasima Noriyuki , Suzuki Hideaki , Gibbins Ann M Verrinder
Published: July 2002

The recently published draft sequence of the human genome will provide a basic reference for the comparative mapping of genomes among mammals. In this study, we selected 214 genes with complete coding sequences on Homo sapiens chromosome 4 (HSA4) to search for orthologs and expressed sequence tag (EST) sequences in eight other mammalian species (cattle, pig, sheep, goat, horse, dog, cat, and rabbit). In particular, 46 of these genes were used as landmarks for comparative mapping of HSA4 and Sus scrofa chromosome 8 (SSC8); most of HSA4 is homologous to SSC8, which is of particular interest because of its association with genes affecting the reproductive performance of pigs. As a reference framework, the 46 genes were selected to represent different cytogenetic bands on HSA4. Polymerase chain reaction (PCR) products amplified from pig DNA were directly sequenced and their orthologous status was confirmed by a BLAST search. These 46 genes, plus 11 microsatellite markers for SSC8, were typed against DNA from a pigmouse radiation hybrid (RH) panel with 110 lines. RHMAP analysis assigned these 57 markers to 3 linkage groups in the porcine genome, 52 to SSC8, 4 to SSC15, and 1 to SSC17. By comparing the order and orientation of orthologous landmark genes on the porcine RH maps with those on the human sequence map, HSA4 was recognized as being split into nine conserved segments with respect to the porcine genome, seven with SSC8, one with SSC15, and one with SSC17. With 41 orthologous gene loci mapped, this report provides the largest functional gene map of SSC8, with 30 of these loci representing new single-gene assignments to SSC8.Key words: orthologous gene, landmark, comparative map, HSA4, SSC8.
Thermodynamics of mixtures containing a very strongly polar compound. Part II. Solid-liquid equilibria for sulfolane + nitrile systems and characterization of the sulfolane-nitrile and sulfolane-1-alkyne interactions in terms of DISQUAC
Authors: Domanska Urszula , Gonzalez Juan Antonio
Published: July 2002

Equilibrium temperatures for solidliquid transitions of mixtures formed by sulfolane and ethanenitrile, propanenitrile, butanenitrile, or pentanenitrile were measured by a dynamic method. The solidliquid equilibria phase diagrams show positive deviations from Raoult's law, except for the system with ethanenitrile, which is nearly ideal. The sulfolanenitrile and sulfolane1-alkyne interactions have been characterized in terms of the DISQUAC group contribution model. DISQUAC properly represents a complete set of thermodynamic properties: solidliquid equilibria, molar excess enthalpies, and natural logarithms of activity coefficients. DISQUAC predictions are valid over a wide temperature range.Key words: solidliquid equilibria, thermodynamics, mixtures, interactions.
MODELLING AND PERFORMANCE EVALUATION OF THE CIRCULATING MULTISEQUENCER, THE MULTI-TOKENS AND THE CONSENSUS ALGORITHMS IN A REAL TIME DISTRIBUTED TRANSACTIONAL SYSTEM
Authors: SAIDANE LEILA AZOUZ , KAMOUN FAROUK
Published: July 2002

In a real-time distribute transactional system, customers generate transactions, which should be scheduled to be executed on different servers. The transactions have temporal constraints and must be executed before their deadlines. To schedule these transactions the circulating mutisequencer, the multi-tokens and the consensus algorithms have been considered to obtain a global view of the system. In this paper, mathematical models are developed to obtain the average stay time of a transaction within the system. These models introduce a bulk arrival M/G/1 station with K classes of customers where bulks are considered according to FIFO discipline and customers (actions) are scheduled according to EDF within a group and with the HOL discipline for the algorithm operating. The response time distribution is also computed. This allowed us to determine the minimum relative deadline, to affect to a generated transaction, to guarantee a given probability p that the transaction does not miss its deadline. The system is then called p-feasible. This study enables to determine the number of tokens to use for the multi-tokens algorithm, for a given number of servers and shows that the circulating mutisequencer algorithm presents the best results.
VERIFICATION IN QUEUE-CONNECTED MULTICOUNTER MACHINES
Authors: IBARRA OSCAR H.
Published: July 2002

We look at a model of a queue system which consists of two nondeterministic finite-state machines, each augmented with "reversal-bounded" counters, connected by an unbounded queue. One machine (the "writer") can send messages to the other (the "reader") via the queue. There is no central control, but the machines operate synchronously and share the same global clock. Unlike in the traditional model, the writer can make conditional moves that test the emptiness of the queue. We investigate the decidability of various verification problems, e.g., (binary, forward, backward) reachability, safety, and blocking. We also look at extensions of the model: allowing the writer to also test for queue emptiness, adding a pushdown stack to one or both of the machines, allowing multiple queues or two-way communication, etc. Finally, we consider some reachability questions concerning machines operating in parallel.
QFT FOR SCALAR PARTICLES IN EXTERNAL FIELDS ON RIEMANNIAN MANIFOLDS
Authors: ISOZAKI HIROSHI
Published: July 2002

We introduce a class of noncompact Riemannian manifolds on which we can argue quantum field theory for scalar particles in external fields. More precisely, we consider quantized linear Klein–Gordon fields subject to (non quantized) electromagnetic forces in a certain class of static space-time. This class is broad enough to include physically important examples of the Euclidean space, the hyperbolic space, and by passing to the natural Lorentzian structure, the Schwarzschild metric up to conformal equivalence. The S-matrix of the massive Klein–Gordon equation on these manifolds is unitarily implemented on the Fock space constructed via the spectrum of the Laplace–Beltrami operator with scalar curvature. We also give the same result for the massless case in the asymptotically flat and hyperbolic spaces.
CAUSAL SPACES, CAUSAL COMPLEMENTS AND THEIR RELATIONS TO QUANTUM FIELD THEORY
Authors: KEYL MICHAEL
Published: July 2002

In this paper the question is analyzed, how it is possilble to reconstruct classical spacetime from the net of local observables of a quantum field theory. To this end different aspects of space-time structure are considered separately. Special attention is drawn to the topological and the causal structure of space-time. Within the scope of causality the differences between causal spaces introduced by Kronheimer and Penrose and causal disjointness relations used in algebraic quantum field theory are considered. Finally we show that the free scalar field on a globally hyperbolic space-time is a special example for our scheme, even if the corresponding Klein-Gordon operator is a Huygens operator.
Does Each Symmetric Operator Have a Stability Domain?
Authors: Neidhardt H. , Zagrebnov V. A.
Published: July 2002

We show that any symmetric operator H has a dense maximal b-stability domain [Formula: see text] (i.e. [Formula: see text], b∈R1) if and only if H is unbounded from above. This abstract result allows an application to singular perturbed Schrödinger operators which are not semi-bounded from below, i.e., to the so-called "fall to the center problem". It turns out that in this case the regularization problem is always ill-posed which implies that there is no unique "right Hamiltonian" for corresponding perturbed system. We give an example of singular perturbed Schrödinger operator for which stability domains are described explicitly.
IDENTIFICATION OF A LANDMARK IN A ROENTGENOGRAPHIC CEPHALOGRAM BY EMPLOYING THE WAVELET NEURONS
Authors: YAMAKAWA TAKESHI , KAWANO HIDEAKI
Published: July 2002

This paper describes an identification method of a landmark in a roentgenographic cephalogram by employing the input-correlated wavelet neurons. For the purpose of improvement of identification precision, a novel pattern matching method, named "wavelet neuron matching (WNM)," is proposed in this paper. Furthermore, the "weighted window", which is proposed in this paper, enables us to consider the orthodontists' knowledge on local information as precisely as possible. The effectiveness and the validity of the proposed method have been verified by the experiments to identify a landmark called Menton.
INVARIANTS FOR SOME REAL HYPERBOLIC GROUPS
Authors: MATSUMOTO KEIJI , YOSHIDA MASAAKI
Published: July 2002

For several discontinuous groups acting on the hyperbolic 3-space, which are commensurable with the group arising from the Whitebread link complement, we construct systems of invariant functions, in terms of theta functions, which give explicit projective embeddings of the quotient spaces.
IMPLICATIONS OF OBSERVED NEUTRINOLESS DOUBLE BETA DECAY
Authors: KLAPDOR-KLEINGROTHAUS H. V. , SARKAR U.
Published: July 2002

Recently a positive indication of the neutrinoless double beta decay has been announced. We study the implications of this result taking into consideration earlier results on atmospheric neutrinos and solar neutrinos. We also include in our discussions the recent results from SNO and K2K. We point out that on the confidence level given for the double beta signal, the neutrino mass matrices are now highly constrained. All models predicting Dirac masses are ruled out and leptogenesis becomes a natural choice. Only the degenerate and the inverted hierarchical solutions are allowed for the three-generation Majorana neutrinos. In both cases we find that the radiative corrections destabilize the solutions and the LOW, VO and Just So solutions of the solar neutrinos are ruled out. For the four-generation case only the inverted hierarchical scenario is allowed.
THE SEIBERG–WITTEN PREPOTENTIAL AND THE EULER CLASS OF THE REDUCED MODULI SPACE OF INSTANTONS
Authors: FLUME R. , STORCH H. , POGHOSSIAN R.
Published: July 2002

The n-instanton contribution to the Seiberg–Witten prepotential of N = 2 supersymmetric d = 4 Yang–Mills theory is represented as the integral of the exponential of an equivariantly exact form. Integrating out an overall scale and a U(1) angle the integral is rewritten as (4n - 3)-fold product of a closed two-form. This two-form is, formally, a representative of the Euler class of the instanton moduli space viewed as a principal U(1) bundle, because its pullback under bundle projection is the exterior derivative of an angular one-form.
A LASER-BASED CALIBRATION SYSTEM, FOR THE CDF PLUG UPGRADE CALORIMETERS
Authors: CAUZ DIEGO
Published: July 2002

A laser-based calibration and monitoring system for the plug upgrade calorimeter is described. A pulsed nitrogen ultraviolet laser excites all of the about 1000 photomultiplier tubes (PMTs) in each plug calorimeter. The light is focused into a quartz fiber and routed first to a primary distributor (PD) and from there to 12 secondary distributors (COWs), which feed the individual PMTs. The system will be used as a debugging tool during calorimeter rigging and will help the wire source calibration system in initially equalizing the PMT gains. In addition, an LED imbedded in each COW can set a continuous DC level on each PMT, allowing for PMT burn-in and gain conditioning.
Φ-MEASURE OF PIONS IN HIGH ENERGY HEAVY-ION COLLISIONS
Authors: ZHANG Q. H.
Published: July 2002

Event-by-event fluctuations for high energy heavy-ion collisions are investigated. The Φ-measures are calculated for pions. It is found that multiparticle symmetrization correlation has great influence on the value of Φ if the phase space density is high. Previous derivation of Φ-measure has neglected multiparticle quantum correlation. So the explanation of Φ-measure as a measure of dynamical correlation is reasonable only when multiparticles quantum correlation effects are smaller. We argue that the Φ-measure might be applicable at the SPS energy where the pion phase space density is much less than one.
SOLUTION OF MASSLESS SPIN ONE WAVE EQUATION IN ROBERTSON–WALKER SPACE–TIME
Authors: SUCU YUSUF , UNAL NURI
Published: July 2002

We generalize the quantum spinor wave equation for photon into the curved space–time and discuss the solutions of this equation in Robertson–Walker space–time and compare them with the solution of the Maxwell equations in the same space–time.
FERMION DETERMINANTS
Authors: FRY M. P.
Published: July 2002

The current status of bounds on and limits of fermion determinants in two, three and four dimensions in QED and QCD is reviewed. A new lower bound on the two-dimensional QED determinant is derived. An outline of the demonstration of the continuity of this determinant at zero mass when the background magnetic field flux is zero is also given.
CONDUCTION MECHANISMS IN IRRADIATED CdSe THIN FILMS
Authors: STOENESCU G.
Published: July 2002

Two conduction regimes defined by different roles of the intercrystalline barriers and crystallites respectively are analyzed for semiconducting polycrystalline vacuum evaporated CdSe thin layers, in strong electric field. We give an interpretation of the effect of fast electrons irradiation on these specific conduction mechanisms. The changing of some microscopic parameters (barrier lengths and potential barriers height) is calculated by fitting the experimental and theoretical I – E characteristics, both for irradiated and unirradiated films. In addition, an extended version of the Antisymmetrized Molecular Dynamics (AMD) method is implemented in order to study clustering aspects for both regimes and to compute the related interaction potentials.
ON THE RELEVANCE OF THE WAVEFUNCTION'S PHASE FACTOR FOR UNDERSTANDING TOPOLOGICAL PROPERTIES OF ATOMS AND MOLECULES IN CONDENSED PHASES: A SIMPLE EXAMPLE
Authors: DELLE SITE L.
Published: July 2002

In preceding work1,2 we proposed a criterion for defining atoms in molecules and in condensed phases based on the determination of the zero flux surface of the quantum current vector which holds the zero flux condition at every point. Here such a surface is calculated analytically in the simple case of a general hydrogen-like wavefunction with a non-constant phase factor. This simple example is then used as a basis to build an easy picture of the basic topological properties of atoms (or molecules) in multiatomic systems; these properties are particularly relevant for a molecular modeling procedure and a subsequent implementation in a simulation scheme. The main goal of this work is to underline with a simple example the importance of the wavefunction's phase factor in defining atoms or molecules in condensed systems (as it has been emphasized in our previous work); this point is important since a largely used theory (for defining atoms and molecules in condensed phases) such as the Bader's theory of atoms in molecules3 systematically neglects the properties of the wavefunction's phase factor.
QCD GLUEBALLS WITHIN A COUPLED CLUSTER APPROACH
Authors: SCHÜTTE D. , WICHMANN A. , WETHKAMP V.
Published: July 2002

The validity of the coupled cluster method is studied within the lattice gauge field theory given by a SU(2) pure glue theory in 2+1 dimensions. Satisfactory convergence is observed for the ground state, but the method is less successful for the prediction of glueballs. We propose to improve the coupled cluster method for excited state by combining it with standard Monte-Carlo techniques which potentially cure the non-hermiticity problems caused by the truncation.
SUB-5-fs REAL-TIME SPECTROSCOPY OF EXCITONIC SYSTEMS
Authors: KOBAYASHI TAKAYOSHI
Published: July 2002

Pump-probe experiment was performed for spin-coated films of conjugated polymers (substituted polydiacetylene) and J-aggregates of a porphyrin derivative by using a sub-5fs visible laser. Real-time spectra were obtained for the systems and new dynamical processes have been observed, i.e. dynamic mode coupling, dynamic intensity borrowing.
PHOTOLUMINESCENCE AND DYNAMICS OF EXCITONS IN Alq3 SINGLE CRYSTALS
Authors: KAWASUMI Y. , AKAI I. , KARASAWA T.
Published: July 2002

The relaxation dynamics of photo-excited states in single crystals of Alq 3, utilized as organic electroluminescent (EL) devices, have been investigated. The photoluminescence (PL) peak of Alq 3 changes depending on the exciting photon energy and the temperature. Nevertheless, a PL peak appears at the same energy position as the EL peak for excitations at energies above the transition edge and a new PL band has been resolved at energies below the EL peak for excitation at the lowest part of the absorption tail. However, for low temperatures and for excitation in the intermediate energy region of the absorption tail, a PL peak appears at the lower energy side. This PL peak shifts into the same energy as the EL peak with increasing temperature. This behavior is explained by a model which takes account of two luminescent states and one non-luminescent intermediate state. In the intermediate energy region, the temperature dependence of the PL for the excitation is also explained by a thermal activation process mediated by the non-luminescent state. The lifetimes of the three states obtained from the temporal profiles of the PL are understood consistently on the basis of this model.
ON THE THEORY OF QUANTUM OSCILLATONS OF THE ELASTIC MODULI IN LAYERED CONDUCTORS
Authors: ZIMBOVSKAYA NATALIYA A. , BIRMAN JOSEPH L.
Published: July 2002

In this paper we study theoretically how the local geometry of the Fermi surface (FS) of a layered conductor can affect quantum oscillations in the thermodynamic observables. We introduce a concrete model of the FS of a layered conductor. The model permits us to analyze the characteristic features of quantum oscillatory phenomena in these materials which occur due to local anomalies of the Gaussian curvature of the FS. Our analysis takes into account strong interaction among quasiparticles and we study the effect of this interaction within the framework of Fermi–liquid theory. We show that singularities in the density of states of quasiparticles (DOS) on the FS which occur at low temperatures near the peaks of its oscillations in a strong magnetic field can be significantly strengthened when the FS of the layered conductor is locally flattened. This can lead to magnetic and lattice instabilities of a special kind which are considered in the final part of the work.
UV PHOTODETECTORS OF c-BN FILMS
Authors: LIAO K. J. , WANG W. L. , CAI C. Z. , WANG X. S. , KONG C. Y.
Published: July 2002

Cubic boron nitride films (c-BN) were prepared by sputtering of a hexagonal BN sintered target. The films obtained were characterized by scanning electron microscopy, Infrared absorption spectra and UV-visible transmission spectra. The UV photodetetor devices of c-BN films were fabricated by photolithographic techniques. The devices exhibited a large photocurrent when exposed to light with a wavelength less than 223nm. The results obtained also show that the photoconductive properties closely depend on the deposition conditions. The photoconductive gain for the sample deposited at r. f. power of 300W was greater than that of the sample prepared at r. f. Power of 100W. This can be ascribed to that the carrier lifetime and mobility of the films have been improved.
UNCONVENTIONAL SPIN DENSITY WAVE IN (TMTSF)2PF6 BELOW T = 4.2 K
Authors: KORIN-HAMZIĆ B. , BASLETIĆ M. , MAKI K.
Published: July 2002

It is well documented that SDW in (TMTSF)2PF6 undergoes another phase transition at T* ≈ 4  K , though the nature of the new phase has not been identified. In particular the angular dependence of the magnetoresistance for B ‖( a, b ′) plane below 4.2 K is dramatically different from the one above 4.2 K. We propose that below T* the new phase unconventional SDW (USDW) appears which modifies drastically the quasiparticle spectrum. The present model describes the observed angular dependence of the magnetoresistance reasonably well, which cannot be interpreted in terms of the conventional SDW.
The Current Contribution to the Thermal Generation of Vortices in HTSC
Authors: Romano' L. , Paracchini C.
Published: July 2002

A model for the current assisted thermal generation of vortices in planar superconductors is proposed. The Lorentz term is added to the vortex-antivortex pairing potential. Following the KT renormalization procedure, one obtains a dependence of the critical current on the temperature and the distribution of the dissipation in the I-T plane.
Electrorheological Effect at Cryogenic Temperature
Authors: Chen Tian-Jie , Zhang X. , Tao R.
Published: July 2002

We have observed a strong electrorheologial (ER) effect of a suspension of fine aluminum particles in liquid nitrogen. The particles have diameter ~ 10μm and an insulate surface. In an ac field, aluminum particles quickly form chains across the two electrodes. The chains vibrate vigorously as the liquid nitrogen has a constant random flow motion caused by bubbles. In addition to low temperature, liquid nitrogen has extremely low viscosity, and low conductivity. These special properties enable us to observe several interesting phenomena which are absent in ER fluids at room temperature. We have determined the rheological properties of our cryogenic ER fluid.
Theory and Experiments on Electrorheological Fluids
Authors: Sheng Ping , Tam Wing Yim , Wen Weijia , Ma Hongru , Yi Guang Hua , Loy M.M.T.
Published: July 2002

By carrying out first principles calculations, particles fabrication and experiments, we demonstrate the enhancement of the electrorheological effect through the use of microstructured composite particles, consisting of a spherical dielectric core coated with a thin layer of metal and an additional outer layer of insulating material with high dielectric constant. It is argued that through the choice of the core material and the outer layer material, the outer layer thickness, and the particle size, there can be a path of continuous improvement on the electrorheological fluid properties that makes possible the eventual fulfillment of the diverse application requirements.
NOISE-INDUCED CHAOS
Authors: GAO J. B. , CHEN C. C. , HWANG S. K. , LIU J. M.
Published: July 2002

Noise-induced chaos is an interesting phenomenon. However, it is a subtle issue because of the difficulty in distinguishing between true low-dimensional chaos and noise. In this review article, we consider how to define noise-induced chaos and what constitutes a test for noise-induced chaos. The mechanism for noise-induced chaos is studied by considering the long-term growth rate of the logarithmic displacement curves. In particular, we have identified three types of diffusional processes, with the third type, the anomalous diffusion, being the precursor of noise-induced chaos. A number of dynamical systems showing different types of diffusional processes are discussed. We have also pointed out when and how a nonlinear noisy system may be mistaken as a chaotic system in general and noise-induced chaos in particular.
CORRELATIONS BETWEEN LOCAL STRUCTURE AND MAGNETISM, PLUS TEMPERATURE DEPENDENT CHANGES IN THE 3D BANDS IN THE COLOSSAL MAGNETORESISTIVE MATERIALS
Authors: BRIDGES FRANK , CAO D. , BOOTH CORWIN
Published: July 2002

Changes in the polaron-like local distortions are strongly correlated with the magnetization in the CMR manganites, for bulk powders, thin films and co-doped material. In addition the e g bands are temperature dependent near T c - but only for CMR materials. These results emphasize the subtle balance of interactions in these systems.
ELECTRO-MECHANICAL COUPLING CHARACTERISTICS OF PZT FOR SENSOR AND ACTUATOR APPLICATION
Authors: TANG F. , HUANG S. L. , HU X. L. , WANG J. T.
Published: July 2002

Piezoelectric ceramics are good candidate materials for sensor and actuator applications, because of its ability to convert mechanical energy to electrical energy and vice versa. The response speed of Electro-mechanical converting signal in piezoelectric transducers is up to a few hundreds kilohertz. Therefore, they are widely used in vibration and acoustic system. In these applications, the nonlinearity of the materials is a main factor to consider when one designs the control system. In this paper, the nonlinearity of electro-mechanical coupling of PbZrxTi(1-x)O3 was investigated. Experimental results showed that the piezoelectric properties of PZT are greatly affected by the sequence and the amplitude of the applied voltage.
OPTICAL EXTENSION OF DICKE'S SUPERRADIANCE: A CASE STUDY OF THALLIUM IN THALLIUM MERCURY SYSTEM
Authors: ADHI SHUBHADA K.
Published: July 2002

A detailed study of superradiance at the Thallium green line (λ=535.0 nm ) in Thallium–Mercury (Tl–Hg) system is reported. High peak power of 1 kW delivered in short pulse duration of 4 nsec (FWHM) has been obtained. Attempts have also been made experimentally to determine the various time constants viz. inhomogeneous dephasing time, decay time, characteristic time, delay time etc. along with their inequality relations for the Tl–Hg system. The experimental results of superradiance in Tl are compared with those predicted theoretically by M. S. Feld et al.2
EFFECTIVE INTERFACE MODELS FOR WETTING
Authors: BOULTER C. J.
Published: July 2002

A review of recent theoretical advances in the study of wetting phenomena is presented concentrating on the application of effective interface models for simple fluids. These models are particularly relevant for elucidating the fluctuation behaviour of unbinding interfaces, with a range of fluctuation regimes being predicted for critical and tricritical wetting. The prediction of a stiffness instability mechanism for critical wetting, caused by the presence of a position-dependent stiffness coefficient, is discussed and quantitative estimates for its relevance are provided. The failure of simple single field models to correctly recover mean-field correlation function behaviour is also demonstrated and an appropriately modified model is introduced to overcome this problem. Comparisons with Monte Carlo simulation results are presented, and a brief tour of the application of interface models to a range of materials and geometries is included.
Thermo-Electric Power of the Bi2Sr2Ca1-xCexCu2Oy System
Authors: Sita D. R. , Singh R.
Published: July 2002

The temperature dependence of thermo-electric power (TEP) of Bi 2 Sr 2 Ca 1-x Ce x Cu 2 O y samples with x upto 0.4 are reported in the temperature range 40–300 K. The normal state TEP data of the superconducting samples are discussed in view of some of the existing theoretical models in the literature, viz. two-band models, Nagaosa and Lee model and a phenomenological narrow band model. The transport in the semiconducting sample is found to be by variable-range-hopping mechanism.
DEVIATIONS FROM SPONTANEOUS LYMAN-α EXPONENTIAL DECAY REVISITED: A RIGOROUS TREATMENT WITHIN A TWO-LEVEL NONRELATIVISTIC MODEL
Authors: SEKE J. , SOLDATOV A. V. , BOGOLUBOV N. N.
Published: July 2002

A recent paper by Facchi and Pascazio, in which the advantage of numerical evaluations of deviations from exponential decay was pointed out, makes a revisitation of the subject necessary. All the more, since the above-mentioned authors have not estimated the error bounds (being absolutely necessary in any calculation) for their results. On the contrary, the accuracy of all results presented in this paper is proved by error estimates. Moreover, for the first time, the power of the simple iteration method in calculating both the exponential and non-exponential time evolution of an unstable atomic state is demonstrated.
FINITE-SIZE SCALING IN TWO-DIMENSIONAL CONTINUUM PERCOLATION MODELS
Authors: NGUYEN VAN LIEN , CANESSA ENRIQUE
Published: July 2002

We test the universal finite-size scaling of the cluster mass order parameter in two-dimensional (2D) isotropic and directed continuum percolation models below the percolation threshold by computer simulations. We found that the simulation data in the 2D continuum models obey the same scaling expression of mass M to sample size L as generally accepted for isotropic lattice problems, but with a positive sign of the slope in the ln–ln plot of M versus L. Another interesting aspect of the finite-size 2D models is also suggested by plotting the normalized mass in 2D continuum and lattice bond percolation models versus an effective percolation parameter, independent of the system structure (i.e., lattice or continuum) and of the possible directions allowed for percolation (i.e., isotropic or directed) in regions close to the percolation thresholds. Our study is the first attempt to map the scaling behavior of the mass for both lattice and continuum model systems into one curve.
CLOSURE PROPERTY OF SPACE-BOUNDED TWO-DIMENSIONAL ALTERNATING TURING MACHINES, PUSHDOWN AUTOMATA, AND COUNTER AUTOMATA
Authors: OKAZAKI TOKIO , INOUE KATSUSHI , ITO AKIRA , WANG YUE
Published: July 2002

This paper investigates closure property of the classes of sets accepted by space-bounded two-dimensional alternating Turing machines (2-atm's) and space-bounded two-dimensional alternating pushdown automata (2-apda's), and space-bounded two-dimensional alternating counter automata (2-aca's). Let L(m, n): N2 → N (N denotes the set of all positive integers) be a function with two variables m (= the number of rows of input tapes) and n (= the number of columns of input tapes). We show that

(i) for any function f(m) = o( log m) (resp. f(m) = o( log m/ log log m)) and any monotonic nondecreasing function g(n) space-constructible by a two-dimensional Turing machine (2-Tm) (resp. two-dimensional pushdown automaton (2-pda)), the class of sets accepted by L(m,n) space-bounded 2-atm's (2-apda's) is not closed under row catenation, row + or projection, and

(ii) for any function f(m) = o(m/ log ) (resp. for any function f(m) such that log f(m) = o( log m)) and any monotonic nondecreasing function g(n) space-constructible by a two-dimensional counter automaton (2-ca), the class of sets accepted by L(m, n) space-bounded 2-aca's is not closed under row catenation, row + or projection,

where L(m, n) = f(m) + g(n) (resp. L(m, n) = f(m) × g(n)).
FINITE STATE LANGUAGE MODELS SMOOTHED USING n-GRAMS
Authors: LLORENS DAVID , VILAR JUAN MIGUEL , CASACUBERTA FRANCISCO
Published: July 2002

We address the problem of smoothing the probability distribution defined by a finite state automaton. Our approach extends the ideas employed for smoothing n-gram models. This extension is obtained by interpreting n-gram models as finite state models. The experiments show that our smoothing improves perplexity over smoothed n-grams and Error Correcting Parsing techniques.