bluuebunny/crossref_metadata_2025 huggingface dataset:
Synthesis of N- and B-Substituted Derivatives of closo-Amino-undecahydro-dodecaborate(1-) Anion
Authors: Grüner Bohumír , Bonnetot Bernard , Mongeot Henri
Published: July 2002

The synthesis of nitrogen and boron substituted derivatives of the 1-amino-closo-dodecaborate anion(1-) 1 is reported. Reasonable yields of the [R2NH-B12H11]- derivatives (R = C6H5CH2, 2-C10H7CH2, n-C16H33, n-C12H25) were obtained via conventional alkylation of 1 in aqueous propan-2-ol, starting from bulky primary alkylhalides. These [R2NH-B12H11]- derivatives were subsequently methylated by dimethyl sulfate under similar conditions. Reaction of 1 with palmitoyl chloride gave under anhydrous conditions the corresponding N-acyl derivative. Reaction of 1 with hydroxymethyl-18-crown-6 tosylate in THF in the presence of NaH led to the novel [(18-crown-6-CH2)2NH-B12H11]- anion, the Cs+ salt of which exhibits unusual solubility properties. A direct cyclization reaction of pentaethylene glycol ditosylate with 1 gave under similar conditions [(15-azacrown)-5-B12H11]-, the first known closo-borate anion with an attached aza-crown ring. These species exhibit potentially interesting complexation efficiency and solubility properties. Selective substitution of the boron cage by a bulky naphthyl substituent was achieved by palladium-mediated cross-coupling reaction between 1 and 1-BrMgC10H7. All derivatives were characterized by high-field 11B, 1H NMR and negative FAB mass spectrometry methods.
Chemistry of Cobalt Bis(dicarbollides). A Review
Authors: Sivaev Igor B. , Bregadze Vladimir I.
Published: July 2002

Synthesis and chemical properties of cobalt bis(dicarbollides) [commo-3,3'-Co(1,2-C2B9H11)2]- and [commo-2,2'-Co(1,7-C2B9H11)2]- and their derivatives are reviewed. An attention is also paid to potential applications of cobalt bis(dicarbollides). A review with 132 references.
Thermomechanical Properties of Radiation-Modified Polyethylene/Ethylene-Propylene-Diene Copolymer/Liquid-Crystalline Copolyester Blends
Authors: Revjakin Oleg , Zicans Janis , Kalnins Martins , Kalkis Valdis , Maksimov Robert D.
Published: July 2002

Radiation-modified blends of high-density polyethylene (PE) with ethylene-propylene-diene copolymer (EPDM; 10-65 wt.%) and thermotropic liquid-crystalline polymer (LCP; 10 wt.%) were investigated. The LCP was a liquid-crystalline copolyester of 40% poly(ethylene terephthalate) with 60% 4-hydroxybenzoic acid. The constituents were blended using a circular extruder, the specimens were prepared by compression molding and irradiated by 60Co γ-radiation up to 200 kGy. Mechanical, thermal, and morphological properties in wide temperature range were investigated for the irradiated and non-irradiated specimens. The effects of irradiation on the thermomechanical behaviour of the PE matrix are discussed. The LCP addition significantly affected the stress-strain behaviour of PE at temperatures above its melting point resulting in some anomalies in kinetics of formation of thermorelaxation stresses, which arise if the material is previously oriented. Thermosetting properties (thermorelaxation stresses and residual setting stresses under conditions of isometric heating and cooling) of the PE/EPDM/LCP blends crosslinked by irradiation and then oriented were also established. The results obtained suggest that such ternary blends improve the application properties of irradiated polyethylene and obtain useful thermosetting materials.
Are There Two Different Geometric Isomers of the O=C=N=C=O Cation?
Authors: Tureček František
Published: July 2002

Re-examination of the O=C=N=C=O+ cation reported previously by Eberlin et al. (J. Chem. Soc., Perkin Trans. 2 1997, 2347) yielded a single local minimum for the C2v bent structure (1a). The D∞h linear structure (1b) reported previously as a local minimum was found to be a second-order stationary point that, upon slight geometry perturbation, collapsed to a C2v transition state (1c) for degenerate inversion of the N-C-N angle in 1a. The ion enthalpy of formation was obtained from the enthalpies of three reactions as ∆Hf,298(1a) = 718 ± 6 kJ mol-1.
Olecranon stress fracture in a weight lifter: a case report
Authors: Rao P S , Rao S K , Navadgi B C
Published: July 2002

Stress fractures have been reported in the upper limb of sportspeople involved in upper limb dominated events. Olecranon stress fractures have been cited in baseball pitchers, javelin throwers, and gymnasts. The unusual case of a stress fracture of the olecranon in a young weight lifter is reported here. The minimally displaced stress fracture was treated with tension band and two Kirschner wires. The fracture healed in four months and the patient returned to light sports activity after six months.
Effects of an endurance cycling competition on resting serum insulin-like growth factor I (IGF-I) and its binding proteins IGFBP-1 and IGFBP-3
Authors: Chicharro J L , López-Calderon A , Hoyos J , Martín-Velasco A I , Villa G , Villanúa M A , Lucía A
Published: July 2002

Objectives—To determine whether consecutive bouts of intense endurance exercise over a three week period alters serum concentrations of insulin-like growth factor I (IGF-I) and/or its binding proteins.

Methods—Seventeen professional cyclists (mean (SEM) Vo2max, 74.7 (2.1) ml/kg/min; age, 27 (1) years) competing in a three week tour race were selected as subjects. Blood samples were collected at each of the following time points: t0(control, before the start of competition), t1(end of first week), and t3(end of third week). Serum levels of both total and free IGF-I and IGF binding proteins 1 and 3 (IGFBP-1 and IGFBP-3) were measured in each of the samples. Cortisol levels were measured in nine subjects.

Results—A significant (p<0.01) increase was found in total IGF-I and IGFBP-1 at both t1and t3compared with to(IGF-I: 110.9 (17.7), 186.8 (12.0), 196.9 (14.7) ng/ml at t0, t1, and t3respectively; IGFBP-1: 54.6 (6.6), 80.6 (8.0), and 89.2 (7.9) ng/ml at t0, t1, and t3respectively). A significant (p<0.01) decrease was noted in free IGF-I at t3compared with both toand t1(t0: 0.9 (0.1) ng/ml; t1: 0.9 (0.1) ng/ml; t3: 0.7 (0.1) ng/ml); in contrast, IGFBP-3 levels remained stable throughout the race.

Conclusions—It would appear that the increase in circulating levels of both IGF-I and its binding protein IGFBP-1 is a short term (one week) endocrine adaptation to endurance exercise. After three weeks of training, total IGF-I and IGFBP-1 remained stable, whereas free IGF-I fell below starting levels.
Distal radial fractures in young goalkeepers: a case for an appropriately sized soccer ball
Authors: Boyd K T , Brownson P , Hunter J B
Published: July 2002

Objectives—To assess the rate of wrist fractures in young goalkeepers sustained by the specific mechanism of “saving the ball” and the potential influence of ball size and environmental conditions.

Methods—A prospective, clinic based study in one institution over a 17 month period. Patients were identified by specific questioning. Information on play circumstances and subsequent clinical progress was documented.

Results—Twenty nine fractures of the distal radius were identified in young goalkeepers (age range 6–15 years) as a direct result of saving the ball. Most were managed simply in a plaster cast. Three patients required minor surgical interventions, and all fractures went on to unite without significant complications. Where ball size was known, 12 of the 15 fractures in children aged 11 years or less occurred as the result of impact with an adult sized ball compared with three when a junior ball was involved. This is statistically significant (p = 0.039). In the 10 children aged 12–15 years, only one fracture involved a junior ball; this is also statistically significant (p = 0.027). Six of the injuries (21%) occurred when the ball was kicked by an adult. Injuries occurred in both organised and informal games throughout the year.

Conclusions—This specific mechanism of injury has not been widely acknowledged nor has the potential influence of ball size as a causative factor been examined. Recommendations for an appropriately sized soccer ball for young players exist but are not in universal use. Increased awareness of this particular injury mechanism is required.
Ethics and health care ‘underfunding’: Figure 1
Authors: Maynard Alan
Published: July 2002

There are continual “crises” in health care systems worldwide as producer and patient groups unify and decry the “underfunding” of health care. Sometimes this cacophony is the self interest of profit seeking producers and often it is advocacy of unproven therapies. Such pressure is to be expected and needs careful management by explicit rationing criteria which determine who gets access to what health care. Science and rationality, however, are unfortunately, rarely the rules of conduct in the medical market-place.
Dust exposure and impairment of lung function at a small iron foundry in a rapidly developing country
Authors: Gomes J , Lloyd O L , Norman N J , Pahwa P
Published: July 2002

OBJECTIVES

A cross sectional prospective study was carried out among iron foundry workers (exposed) and soft drink bottling and supply company workers (unexposed) to assess their occupational exposure to ambient respiratory dust in their work environment and its effect on their lung function profile.

PARTICIPANTS

Lung function was measured in 81 exposed and 113 unexposed workers. Personal respirable dust concentrations were measured for all the exposed and the unexposed workers. Information on respiratory signs and symptoms was also collected from the participants.

RESULTS

Among the exposed workers, midexpiratory flow (FEF25-75), forced expiratory volume in 1 second (FEV1), peak expiratory flow (PEF), FEV1/FVC, and FEV1/VC ratios were significantly lower whereas the vital capacity (VC) and forced vital capacity (FVC) were non-significantly higher. Job at the iron foundry was a significant predictor of lung function. Exposure to high concentration of respirable dust at the iron foundry was also a significant predictor. Workers working in high exposure areas (general works, furnace, continuous casting areas, and fabrication workshop) had lower lung function values than workers in medium and low exposure areas. Smoking did not enhance the effects of exposure to dust on lung function.

CONCLUSIONS

Exposure to respirable dust was higher among the iron foundry workers; and among these, general, furnace, rolling mill, and fabrication workers had higher exposures to dust than did workers in continuous casting, the mechanical workshop, and the bottling plant. Job type and exposure to dust were significant predictors of lung function. Implementation of industrial hygiene and proper and efficient use of personal protection equipment while at work could help to protect the respiratory health of industrial workers.
Osteomyelitis and possible endocarditis secondary to Lactococcus garvieae: a first case report
Authors: James P Rachael , Hardman Suzanna M C , Patterson David L H
Published: July 2002

Although osteomyelitis is commonly caused by staphylococcal infection, the first case of a lumbar osteomyelitis secondary to Lactococcus garvieaeis reported. The case was complicated by possible endocarditis of an aortic valve prosthesis.
Management of leg ulcers
Authors: Sarkar P K , Ballantyne S
Published: July 2002

Leg ulcer is a leading cause of morbidity among older subjects, especially women in the Western world. About 400 years BC, Hippocrates wrote, “In case of an ulcer, it is not expedient to stand, especially if the ulcer be situated on the leg”. Hippocrates himself had a leg ulcer. The best treatment of any leg ulcer depends upon the accurate diagnosis and the underlying aetiology. The majority of leg ulcers are due to venous disease and/or arterial disease, but the treatment of the underlying cause is far more important than the choice of dressing. The aetiology, pathogenesis, treatment, and the future trends in the management of the leg ulcers are discussed in this review.
Evaluation of local invasion by oesophageal carcinoma—a prospective study of prone computed tomography scanning
Authors: Wayman J , Chakraverty S , Griffin S M , Doyle G J , Keir M J , Simpson W
Published: July 2002

The aim of this study was to assess the value of prone computed tomography compared with the traditional supine position, in the assessment of invasion of adjacent mediastinal structures by oesophageal cancer. A prospective, single blind case-case comparative study of signs of local tumour invasion was conducted. Sixty nine consecutive patients undergoing computed tomography for preoperative staging of oesophageal carcinoma were studied. Computed tomography scanning of the thorax was performed in the standard supine followed by prone position; in 39 patients the computed tomography findings were correlated with the surgical findings. Four established radiological signs used to assess mediastinal invasion were scored in each case.

Based on the radiological scoring system, there was a significant down staging in the probability of aortic invasion in 12 of the 69 cases (p<0.05). A similar improvement in accuracy was seen in the cases undergoing surgery; of the 38 cases who did not have aortic invasion at operation, 10 cases were scored as high for aortic invasion on the supine scans compared with only three on the prone position (p<0.05). Prone scanning was not of significant additional value in the assessment of major airway or pericardial invasion.

Modification of the computed tomography protocol to include scanning in the prone position will improve the accuracy of the preoperative staging of patients with oesophageal malignancy and reduce the chance of overstaging disease. Especially in centres where endoscopic ultrasound is not available, our modification may reduce the chance of denying patients potentially curative operations.
Management of shoulder pain in patients with stroke
Authors: Walsh K
Published: July 2002

Shoulder pain affects from 16% to 72% of patients after a cerebrovascular accident. Hemiplegic shoulder pain causes considerable distress and reduced activity and can markedly hinder rehabilitation. The aetiology of hemiplegic shoulder pain is probably multifactorial. The ideal management of hemiplegic stroke pain is prevention. For prophylaxis to be effective, it must begin immediately after the stroke. Awareness of potential injuries to the shoulder joint reduces the frequency of shoulder pain after stroke. The multidisciplinary team, patients, and carers should be provided with instructions on how to avoid injuries to the affected limb. Foam supports or shoulder strapping may be used to prevent shoulder pain. Overarm slings should be avoided. Treatment of shoulder pain after stroke should start with simple analgesics. If shoulder pain persists, treatment should include high intensity transcutaneous electrical nerve stimulation or functional electrical stimulation. Intra-articular steroid injections may be used in resistant cases.
Using the global positioning system to map disturbance patterns of forest harvesting machinery
Authors: McDonald T P , Carter E A , Taylor S E
Published: July 2002

A method was presented to transform sampled machine positional data obtained from a global positioning system (GPS) receiver into a two-dimensional raster map of number of passes as a function of location. The effect of three sources of error in the transformation process were investigated: path sampling rate (receiver sampling frequency); output raster resolution; and GPS receiver errors. Total accuracy of traffic maps across a site (the summed areas receiving one, two, three, etc. passes) was not greatly affected by the error sources. The estimate of number of passes at a specific point, however, was heavily dependent on the presence of errors in the input data. Adding random offsets to each GPS position, for example, resulted in less than a 35% chance that an individual pixel would be classified correctly following transformation when compared with a reference raster. Although the absolute accuracy of the GPStransformation system was not defined, it was concluded that data derived from applying it could be used to make estimates of total site disturbance and to identify regions of higher or lower disturbance but was less effective when applied in defining number of passes at a given point in a stand.
Soil disturbance and 10-year growth response of coast Douglas-fir on nontilled and tilled skid trails in the Oregon Cascades
Authors: Heninger Ronald , Scott William , Dobkowski Alex , Miller Richard , Anderson Harry , Duke Steve
Published: July 2002

We (i) quantified effects of skidder yarding on soil properties and seedling growth in a portion of western Oregon, (ii) determined if tilling skid trails improved tree growth, and (iii) compared results with those from an earlier investigation in coastal Washington. Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) seedlings were hand planted at eight recent clearcuts in skid ruts in either nontilled or tilled trails, in adjacent soil berms, and in adjacent logged-only portions. Four and 5 years after skidding, rut depths averaged 15 cm below the original soil surface; mean fine-soil bulk density (030 cm depth) below ruts of nontilled trails exceeded that on logged-only portions by 14%. Height growth on nontilled trails averaged 24% less than on logged-only portions in year 4 after planting and decreased to 6% less in year 7. For years 810, mean height growth was similar for all treatments. Reduced height growth lasted for about 7 years compared with 2 years for coastal Washington. Ten years after planting, trees in skid-trail ruts averaged 10% shorter with 29% less volume than those on logged-only portions. Tillage improved height and volume growth to equal that on logged-only portions. Generalizations about negative effects of skid trails on tree growth have limited geographic scope.
A fluorescent compound for glucose uptake measurements in isolated rat cardiomyocytes
Authors: Ball S W , Bailey J R , Stewart J M , Vogels C M , Westcott S A
Published: July 2002

A focus of current diabetes research is the development of insulinomimetic compounds for oral treatment of diabetes and its associated cardiac complications. Screening compounds for their potential insulinomimetic effects usually involves the use of radioactive isotopes. The focus of this study was to investigate a nonradioactive fluorescent compound for its use in screening insulinomimetic compounds. The indicator 2-(N-(7-nitrobenz-2-oxa-1,3-diazol-4-yl)amino)-2-deoxyglucose (2-NBDG) has been used by some workers to measure glucose uptake in Escherichia coli and Candida albicans. We propose that 2-NBDG will also be a suitable indicator for mammalian cell lines, in particular rat cardiomyocytes. We found that the indicator could give a reliable reproducible standard curve following appropriate dilution and is taken up by isolated cardiomyocytes. The insulinomimetic compounds vanadyl sulfate and sodium molybdate showed rates of glucose uptake similar to that of insulin. Furthermore, the rate of uptake measured for insulin using this technique (0.04 ± 0.003 nmol·min1·106 cells1) is comparable with previous literature using 2-deoxyglucose uptake measurements on isolated myocytes (0.040 nmol·min1·106 cells1), demonstrating the validity of this fluorescent compound for glucose uptake studies.Key words: cardiomyocytes, fluorescent deoxyglucose, glucose uptake, insulin mimics.
SOME SUFFICIENT CONDITIONS OF LEARNABILITY IN THE LIMIT FROM POSITIVE DATA
Authors: OKADOME TAKESI
Published: July 2002

The paper deals with learning in the limit from positive data. After an introduction and overview of earlier results, we strengthen a result of Sato and Umayahara (1991) by establishing a necessary and sufficient condition for the satisfaction of Angluin's (1980) finite tell-tale condition. Our other two results show that two notions introduced here, the finite net property and the weak finite net property, lead to sufficient conditions for learning in the limit from positive data. Examples not solvable by earlier methods are also given.
TWO-POINT FUNCTIONS AND QUANTUM FIELDS IN DE SITTER UNIVERSE
Authors: BROS JACQUES , MOSCHELLA UGO
Published: July 2002

We present a theory of general two-point functions and of generalized free fields in d-dimensional de Sitter space-time which closely parallels the corresponding Minkowskian theory. The usual spectral condition is now replaced by a certain geodesic spectral condition, equivalent to a precise thermal characterization of the corresponding “vacuum” states. Our method is based on the geometry of the complex de Sitter space-time and on the introduction of a class of holomorphic functions on this manifold, called perikernels, which reproduce mutatis mutandis the structural properties of the two-point correlation functions of the Minkowskian quantum field theory. The theory contains as basic elementary case the linear massive field models in their “preferred” representation. The latter are described by the introduction of de Sitter plane waves in their tube domains which lead to a new integral representation of the two-point functions and to a Fourier-Laplace type transformation on the hyperboloid. The Hilbert space structure of these theories is then analysed by using this transformation. In particular we show the Reeh-Schlieder property. For general two-point functions, a substitute to the Wick rotation is defined both in complex space-time and in the complex mass variable, and substantial results concerning the derivation of Källen-Lehmann type representation are obtained.
A TORELLI THEOREM FOR SPECIAL DIVISOR VARIETIES X ASSOCIATED TO DOUBLY COVERED CURVES ${\tilde C}/C$
Authors: SMITH ROY , VARLEY ROBERT
Published: July 2002

Let Ci, i=1,2, be two smooth non-hyperelliptic curves over the complex numbers of genus g≥ 3, and [Formula: see text] connected étale double covers, such that the theta divisors Ξi of the associated Prym varieties (pi, Ξi) are non singular in codimension ≤ 3. If [Formula: see text] are the norm maps, then Ξi is isomorphic to {[Formula: see text] and h0 (L) is even and positive}. Then the Abel maps define generic ℙ1 bundles Xi→Ξi, where Xi is the special divisor variety [Formula: see text] and [Formula: see text] even}. We prove, under the hypotheses above, that biregular isomorphism of the special divisor varieties X1≅ X2 implies isomorphism of the double covers [Formula: see text].
A GEOMETRIC VERSION OF DYSON'S LEMMA FOR FACTORS OF ARBITRARY DIMENSION
Authors: WESSLER MARKUS
Published: July 2002

This paper generalizes the geometric part of the Esnault–Viehweg paper on Dyson's Lemma for a product of projective lines. Using the method of weak positivity from algebraic geometry, we are able to study products of smooth projective varieties of arbitrary dimension and to prove a geometric analogue of Dyson's Lemma for this case. Our main result is in fact a quantitative version of Faltings' product theorem.
OPTIMIZATION OF A DISTRIBUTED GENETIC ALGORITHM ON A CLUSTER OF WORKSTATIONS FOR THE DETECTION OF MICROCALCIFICATIONS
Authors: BEVILACQUA A. , CAMPANINI R. , LANCONELLI N.
Published: July 2002

We have developed a method for the detection of clusters of microcalcifications in digital mammograms. Here, we present a genetic algorithm used to optimize the choice of the parameters in the detection scheme. The optimization has allowed the improvement of the performance, the detailed study of the influence of the various parameters on the performance and an accurate investigation of the behavior of the detection method on unknown cases. We reach a sensitivity of 96.2% with 0.7 false positive clusters per image on the Nijmegen database; we are also able to identify the most significant parameters. In addition, we have examined the feasibility of a distributed genetic algorithm implemented on a non-dedicated Cluster Of Workstations. We get very good results both in terms of quality and efficiency.
INTERMITTENT COLLECTIVE BEHAVIOR IN CELLULAR AUTOMATA
Authors: JIMÉNEZ-MORALES F.
Published: July 2002

We show that the intermittent collective behavior shown by several CA has the statistical properties of the on–off intermittency. The average transient time for trajectories to fall in a ε neighborhood of the off state scales with ε-1. The laminar and burst phases are symmetric and the scaling exponent is -3/2 for the distribution of the phases. Also, we show that the size distribution of clusters follows a power law with a scaling exponent of -2.
A NONLINEAR SUPER-EXPONENTIAL RATIONAL MODEL OF SPECULATIVE FINANCIAL BUBBLES
Authors: SORNETTE D. , ANDERSEN J. V.
Published: July 2002

Keeping a basic tenet of economic theory, rational expectations, we model the nonlinear positive feedback between agents in the stock market as an interplay between nonlinearity and multiplicative noise. The derived hyperbolic stochastic finite-time singularity formula transforms a Gaussian white noise into a rich time series possessing all the stylized facts of empirical prices, as well as accelerated speculative bubbles preceding crashes. We use the formula to invert the two years of price history prior to the recent crash on the Nasdaq (April 2000) and prior to the crash in the Hong Kong market associated with the Asian crisis in early 1994. These complex price dynamics are captured using only one exponent controlling the explosion, the variance and mean of the underlying random walk. This offers a new and powerful detection tool of speculative bubbles and herding behavior.
CP-VIOLATION IN NEUTRINO OSCILLATIONS AND L/E FLATNESS OF THE E-LIKE EVENT RATIO AT SUPER-KAMIOKANDE
Authors: AHLUWALIA D. V. , LIU Y. , STANCU I.
Published: July 2002

We show that if the presently observed L/E-flatness of the electron-like event ratio in the Super-Kamiokande atmospheric neutrino data is confirmed, then the indicated ratio must be unity. Further, it is found that once CP is violated the exact L/E flatness implies: (a) the CP-violating phase, in the standard parametrization, is narrowed down to two possibilities ±π/2, and (b) the mixing between the second and the third generations must be maximal. With these results at hand, we argue that a dedicated study of the L/E-flatness of the electron-like event ratio by Super-Kamiokande can serve as an initial investigatory probe of CP violation in the neutrino sector. The assumptions under which these results hold are explicitly stated.
QUANTIZATION OF MASSIVE ABELIAN ANTISYMMETRIC TENSOR FIELD AND LINEAR POTENTIAL
Authors: DEGUCHI SHINICHI , KOKUBO YOUSUKE
Published: July 2002

We discuss a quantum-theoretical aspect of the massive Abelian antisymmetric tensor gauge theory with antisymmetric tensor current. To this end, an Abelian rank-2 antisymmetric tensor field is quantized both in the covariant gauge with an arbitrary gauge parameter and in the axial gauge of the Landau type. The covariant quantization yields the generating functional written in terms of an antisymmetric tensor current and its divergence. Origins of the terms in the generating functional are clearly understood in comparison with the quantization in the unitary gauge. The quantization in the axial gauge with a suitable axis directly yields the generating functional which is the same as that obtained by using Zwanziger's formulation for electric and magnetic charges. It is shown that the generating functionals lead to a composite of the Yukawa and the linear potentials.
AN EFFECTIVE QUANTUM MECHANISM FOR MASS GENERATION IN DIFFEOMORPHISM-INVARIANT THEORIES
Authors: JARAMILLO J. L. , ALDAYA V.
Published: July 2002

We propose a scenario for particle-mass generation, assuming the existence of a physical regime where, firstly, physical particles can be considered as point-like objects moving in a background space–time and, secondly, their mere presence spoils the invariance under the local diffeomorphism group, resulting in an anomalous realization of the latter. Under these hypotheses, we describe mass generation starting from the massless free theory. The mechanism is not sensitive to the detailed description of the underlying theory at higher energies, leaning only on general structural features of it, specifically diffeomorphism invariance.
CHIRAL FERMIONS ON THE LATTICE AND INDEX RELATIONS
Authors: KERLER WERNER
Published: July 2002

Comparing recent lattice results on chiral fermions and old continuum results for the index puzzling questions arise. To clarify this issue we start with a critical reconsideration of the results on finite lattices. We then work out various aspects of the continuum limit. After determining bounds and norm convergences we obtain the limit of the anomaly term. Collecting our results the index relation of the quantized theory gets established. We then compare in detail with the Atiyah–Singer theorem. Finally we analyze conventional continuum approaches.
EXACT FINITE UNIFIED THEORIES
Authors: KOBAYASHI T. , KUBO J. , MONDRAGÓN M. , ZOUPANOS G.
Published: July 2002

Finite Unified Theories are N=1 supersymmetric GUT's that can be made finite beyond the unification point, including the softly broken sector. The new characteristic predictions of FUTs are: 1) The lightest Higgs boson mass is predicted to be in the window 120-130 GeV, in case the LSP is neutralino, while in case the LSP is the [Formula: see text] (which can be consistently accommodated in presence of bilinear R-parity violating terms) it can be as light as 111 GeV. 2) The s-spectrum starts above several hundreds of GeV.
COLLAPSING SHELLS OF RADIATION IN HIGHER DIMENSIONAL SPACE–TIME AND COSMIC CENSORSHIP CONJECTURE
Authors: GHOSH S. G. , SARAYKAR R. V. , BEESHAM A.
Published: July 2002

Gravitational collapse of radiation shells in a non-self-similar higher dimensional spherically symmetric space–time is studied. Strong curvature naked singularities form a highly inhomogeneous collapse, violating the cosmic censorship conjecture. As a special case, self similar models can be constructed.
BOSONIC TOPCOLOR
Authors: Aranda Alfredo , Carone Christopher D.
Published: July 2002

A topcolor model is presented that contains both composite and fundamental scalar fields. Strong dynamics accounts for most of the top quark mass and part of the electroweak symmetry breaking scale. The fundamental scalar is weakly coupled and transmits its share of electroweak symmetry breaking to the light fermions. The model is allowed by the current experimental bounds, and can give a potentially large contribution to [Formula: see text] mixing.
HAMILTONIAN vs LAGRANGIAN EMBEDDING OF A MASSIVE SPIN-ONE THEORY INVOLVING TWO-FORM FIELD
Authors: HARIKUMAR E. , SIVAKUMAR M.
Published: July 2002

We consider the Hamiltonian and Lagrangian embedding of a first-order, massive spin-one, gauge noninvariant theory involving antisymmetric tensor field. We apply the BFV–BRST generalized canonical approach to convert the model to a first class system and construct nilpotent BFV–BRST charge and a unitarizing Hamiltonian. The canonical analysis of the Stückelberg formulation of this model is presented. We bring out the contrasting feature in the constraint structure, specifically with respect to the reducibility aspect, of the Hamiltonian and the Lagrangian embedded model. We show that to obtain manifestly covariant Stückelberg Lagrangian from the BFV embedded Hamiltonian, phase space has to be further enlarged and show how the reducible gauge structure emerges in the embedded model.
DOPED STRIPES EVOLVING FROM THE ONE-HOLE PROPERTIES OF THE ANTIFERROMAGNETIC INSULATOR
Authors: DAGOTTO E. , MARTINS G. B.
Published: July 2002

Recent investigations in the context of the standard and extended t-J models using computational techniques are here described. In regimes of couplings producing a one-hole dispersion compatible with photoemission data for the parent insulator, the one-hole states have strong antiferromagnetic correlations across-the-hole, particularly at momenta (0,π)-(π,0). This effect is rationalized as a tendency toward spin-charge separation in two-dimensions at short distances. At finite hole density, doped stripes are observed. The elementary building block of the stripes resembles the spin arrangement around individual holes. This suggests that the seed of doped stripes already exist in the unusual properties of the insulating parent compound. Stripes are conjectured to originate in a "frustrated spin-charge separation" effect, different from other theories valid at large J/t discussed in previous literature.
A CONSTRAINED PATH MONTE CARLO METHOD FOR NUCLEON SYSTEMS
Authors: SCHMIDT K. E. , SARSA A. , FANTONI S.
Published: July 2002

By combining diffusion Monte Carlo for the spatial degrees of freedom and auxiliary field Monte Carlo to separate the spin-isospin operators, we can solve for the ground state of many-nucleon systems. We use a path constraint to control the fermion sign problem and apply the method to neutron systems interacting with the Argonne v′8 two nucleon potential and the Urbana IX three-nucleon potential. We compare our results with fermion hypernetted chain calculations.
EXCITONS IN COLLOIDAL CuI PARTICLES DISPERSED IN A KI CRYSTAL
Authors: HIRAI T. , EDAMATSU K. , ITOH T. , HARADA Y. , HASHIMOTO S.
Published: July 2002

We have investigated the luminescence spectra of colloidal CuI particles dispersed in a KI crystal under low- and high-density excitations of the CuI particles at low temperatures. Under the low-density excitation, we have observed the luminescence of both confined and bulk-like exciton transitions in the CuI particles with zincblende and two kinds of hexagonal structures. In the bulk-like particles with the zincblende structure, the emission line of bound excitons with small binding energy of ~5 meV has been recognized. The biexciton luminescence has been observed under the high-density excitation. We discuss the origins of the various excitonic states observed in the CuI particles dispersed in the KI crystal.
2LO RESONANT RELAXATION OF EXCITON POLARITON INTO LONGITUDINAL EXCITON STATE IN β-ZnP2
Authors: NAKAMURA K. , UMEMOTO S. , ARIMOTO O.
Published: July 2002

Efficiency dip is observed at 2LO phonon energy above the 1s longitudinal exciton energy in excitation spectra for 1s exciton luminescence band in β- ZnP 2 at 2K. This dip comes from the 2LO resonant relaxation of exciton polariton into the longitudinal exciton state which plays a role of the killer of exciton polaritons in β- ZnP 2. Increase of nonradiative processes is checked by the photocalorimetric (PC) measurement. The PC response is not affected by the resonant 2LO process. Relaxation processes of exciton polaritons and energy dissipation are discussed.
FLOWER-LIKE SQUEEZING IN THE MOTION OF A LASER-DRIVEN TRAPPED ION
Authors: AN NGUYEN BA , DUC TRUONG MINH
Published: July 2002

We investigate the Nth order amplitude squeezing in the fan-state |ξ;2k,f> F which is a linear superposition of the 2k-quantum nonlinear coherent states. Unlike in usual states where an ellipse is the symbol of squeezing, a 4k-winged flower results in the fan state. We first derive the analytical expression of squeezing for arbitrary k, N, f and then study in detail the case of a laser-driven trapped ion characterized by a specific form of the nonlinear function f. We show that the lowest order in which squeezing may appear and the number of directions along which the amplitude may be squeezed depend only on k whereas the precise directions of squeezing are determined also by the other physical parameters involved. Finally, we present a scheme to produce such fan-states.
THE OPTICAL PROPERTIES AND QUANTUM-SIZE EFFECTS IN THE AMORPHOUS HYDROGENIZED a-C:H/a-Si:H DIAMOND-LIKE FILMS
Authors: BABAEV A. A. , ABDULVAGABOV M. Sh. , GABIBOV F. S.
Published: July 2002

It is studied the absorption edge and photoluminescence (4.2-900 K) in the a-C:H films on silica substrates prepared by the decomposition of 10%CH4+90%Ar gas mixture in the RF plasma under various growth conditions E/p (E – electric field strength, p – gas mixture pressure). With E/p increase, the optical band gap width and Tauc slope decrease, photoluminescence intensity and photoluminescence excitation spectra shift to a lower energy region while halfwidth of the photoluminescence intensity spectra broadens. It is firstly fabricated the multilayer low-size a-C:H/a-Si:H structures where a-C:H layer with E g = 4.5 eV is used as a barrier. Quantum size effects are found in a-Si:H with the thickness lower than 100 Å. Photoluminescence studies of a-Si:H show the presence of a sharp interface region in the a-C:H/a-Si:H structures where the charge carriers exist in the state of quantization.
DETERMINATION OF PROPERTIES OF THIN FILMS USING X-RAY REFLECTIVITY
Authors: CHEW K. , YOON S. F. , CHAN H. K. , NG C. F. , ZHANG Q. , AHN J.
Published: July 2002

X-ray reflectivity (XRR) is a sensitive and non-destructive technique for the characterization of surfaces and thin film properties. Due to the spectroscopic nature of the problem, the unknown parameters are solved indirectly by fitting the theoretical reflectivity spectra to the experimental spectra. In this work, we propose three algorithms that allow the direct determination of the properties, which are more efficient compared to the fitting process that requires initial guesses, and whose convergence depends critically on the goodness of the guesses. The algorithms are developed for a structure with a one-layer film on a substrate. However, for films having an additional top surface layer, or an interface layer next to the substrate, the algorithms can also be applied to approximately deduce the parameters of the main layer of film.
MECHANISM OF MgB2 SUPERCONDUCTIVITY WITH INTERBAND PAIR-TRANSFER INTERACTION
Authors: KRISTOFFEL N. , ÖRD T. , RÄGO K.
Published: July 2002

A two-band scheme of MgB2 superconductivity is developed. It comprises repulsive interband transfer of intraband pairs between effective σ- and π-bands together with σ-intraband electron–phonon attraction and Coulomb interaction. The interaction constants are found by fitting T c , specific heat jump and zero-temperature gaps ratio. The gaps and specific heat dependences on temperature besides the T c isotope effect exponent, calculated without any additional free parameters, agree with the experiment. T c versus chemical potential shows a broad maximum to which the "autodoped" MgB2 belongs.
MUTUALLY LOCAL FIELDS FROM FORM FACTORS
Authors: FRING ANDREAS
Published: July 2002

We compare two different methods of computing form factors. One is the well established procedure of solving the form factor consistency equations and the other is to represent the field content as well as the particle creation operators in terms of fermionic Fock operators. We compute the corresponding matrix elements for the complex free fermion and the Federbush model. The matrix elements only satisfy the form factor consistency equations involving anyonic factors of local commutativity when the corresponding operators are local. We carry out the ultraviolet limit, analyze the momentum space cluster properties and demonstrate how the Federbush model can be obtained from the SU(3)3-homogeneous sine-Gordon model. We propose a new class of Lagrangians which constitute a generalization of the Federbush model in a Lie algebraic fashion. For these models we evaluate the associated scattering matrices from first principles, which can alternatively also be obtained in a certain limit of the homogeneous sine-Gordon models.
INTERFACE STRUCTURE
Authors: PERCUS J. K.
Published: July 2002

Phase-separated fluids are analyzed from several viewpoints: local thermodynamic, in which all density correlations are ignored; mean field, which correctly treats those at medium range; and a modified Kac-Siegert form which only coarse-grains those at short range. The last form appears as an ensemble average over tail potential fields, and is treated variationally with a Gaussian ansatz. Application to a planar interface shows the anticipated surface softening as any confining field is removed, and in statistically homogeneous condensation, a form of the familiar level set description assumes relevance. Suggestions are made as to removing the Gaussian assumption.
Feasibility of a 5 T Magnet by using Bi-2223/Ag Tape at 30 K
Authors: Matrone A. , Ariante M. , Cavaliere V. , Mariani M. , Masullo G. , Petrillo E. , Quarantiello R. , Bigoni L. , Martini L. , Grasso G. , Siri A. S.
Published: July 2002

The feasibility of a 5 T magnet by using Bi-2223/Ag tapes at 30 K has been investigated. Preliminary computation demonstrates that the target is attainable by assembling 20 double pancakes manufactured by co-winding two Bi-2223/Ag tapes having overall cross-section of 0.25 × 3.5 mm 2 and 25% fill factor, being the expected operating current about 200 A. The pancakes located at the edges are the most critical because the component of the magnetic field orthogonal to the tape surface is large enough to strongly depress J c . To overcome this problem the edge pancakes could be fabricated by using Bi-2223/Ag tapes with new concept design (e.g. with oriented filaments).
EFFECTS OF c-AXIS HOPPING IN THE INTERLAYER TUNNELING MODEL OF HIGH-Tc LAYERED CUPRATES
Authors: CHATTOPADHYAY BIPLAB , DAS A. N.
Published: July 2002

We consider the interlayer pair-tunneling model for layered cuprates, including an effective single particle hopping along the c-axis. A phenomenological suppression of the c-axis hopping matrix element, by the pseudogap in cuprate superconductors, is incorporated. At optimal doping, quantities characteristic to the superconducting state, such as the transition temperature and the superconducting gap are calculated. Results from our calculations are consistent with the experimental observations with the noteworthy point that, the superconducting gap as a function of temperature shows excellent match to the experimental data. Predictions within the model, regarding T c variation with interlayer coupling, are natural outcomes which could be tested further.
NOVEL MAGNETISM AND SUPERCONDUCTIVITY IN A Ru-BASED DOUBLE PEROVSKITE
Authors: WU M. K. , CHEN D. Y. , CHIEN F. Z. , LING D. C. , CHEN Y. Y. , REN H. C.
Published: July 2002

We report the observations, using magnetic susceptibility and specific heat measurements, of the coexistence of superconductivity and magnetic ordering at low temperatures in the Cu-doping double perovskites Sr 2 ARu 1-x Cu x O 6, with A = Y or Ho, and x<0.2. The observed striking features can be understood in terms of a plausible theoretical model based on the double exchange mechanism, which occurs indirectly via Ru 5+ spin coupling to itinerant electrons hopping from one Ru site to another.
LOCAL ORDER AND MAGNETIC FIELD EFFECTS ON THE ELECTRONIC PROPERTIES OF DISORDERED BINARY ALLOYS IN THE QUANTUM SITE PERCOLATION LIMIT
Authors: MELLO D. F. DE , CABRERA G. G.
Published: July 2002

Electronic properties of disordered binary alloys are studied via the calculation of the average Density of States (DOS) in two and three dimensions. We propose a new approximate scheme that allows for the inclusion of local order effects in finite geometries and extrapolates the behavior of infinite systems following finite-size scaling ideas. We particularly investigate the limit of the Quantum Site Percolation regime described by a tight-binding Hamiltonian. This limit was chosen to probe the role of short range order (SRO) properties under extreme conditions. The method is numerically highly efficient and asymptotically exact in important limits, predicting the correct DOS structure as a function of the SRO parameters. Magnetic field effects can also be included in our model to study the interplay of local order and the shifted quantum interference driven by the field. The average DOS is highly sensitive to changes in the SRO properties and striking effects are observed when a magnetic field is applied near the segregated regime. The new effects observed are twofold: there is a reduction of the band width and the formation of a gap in the middle of the band, both as a consequence of destructive interference of electronic paths and the loss of coherence for particular values of the magnetic field. The above phenomena are periodic in the magnetic flux. For other limits that imply strong localization, the magnetic field produces minor changes in the structure of the average DOS.
THE ANOMALOUS METALLIC FERROMAGNETIC STATE OF Sr DOPED MANGANITES
Authors: FERRARI V. , ROZENBERG M. J. , WEHT R.
Published: July 2002

We deduce a model relevant for the anomalous metallic state of Sr doped manganites at low temperatures within the ferromagnetic phase. It provides a natural explanation for several anomalous features observed experimentally, such as the small Drude contribution in optical conductivity, the "pseudo-gap" in the density of states, and the unusual dispersion observed in photoemission.
PROBING FOR FLUORINE IN NITRIDED SiO2 FILMS BY ION BEAM ANALYSIS
Authors: JOHN KENNEDY V. , MARKWITZ ANDREAS , WHITE G. V. , BROWN I. W. M.
Published: July 2002

Particle induced γ-ray emission (PIGE) using the 19 F ( p , α γ)16 O reaction and deuterium induced nuclear reaction analysis (NRA) were used to measure the uptake of fluorine in thin silicon oxide films which varied in thickness and had been nitrided under various conditions and annealing treatments. PIGE results show that 66 – 80 ppm of F was found in samples nitrided with F (as approximately 1% SiF 4) in flowing nitrogen and heated at 1300°C for 1 hour. With NRA, it was not possible to measure these low concentrations because the background signal from silicon overlaps with the F signal. The increase of F in the nitrided specimens from 66 to 80 ppm follows an increase in film thickness from 3 to 53 nm indicating that F is incorporated in the film rather than being located at the surface of the specimen.
A PROCEDURE FOR GOLD SOLDERING USING A Si-Au ALLOY PRODUCED BY Si IMPLANTATION IN Au
Authors: JOHN KENNEDY V. , TERWAGNE G. , DEMORTIER G.
Published: July 2002

Pure polycrystalline Au foils were rolled at room temperature to a thickness of 35 μm. Different doses of high energy Si ions (0.2-4.5 MeV) obtained from the 2 MV Tandetron accelerator at LARN were implanted in polycrystalline Au foils to produce a low melting point Au-Si alloy. Au-Si eutectic structure has been observed in the implanted Au foils after annealing at 400°C for 1 h. The Au-Si liquid phase diffused into the polycrystalline Au foil along the grain boundaries, which were flattened by the initial rolling procedure. The presence of this eutectic alloy was observed by Secondary Electron Microscopy (SEM) of the Au foil. Nuclear (d,p) reactions induced by deuterons have been used to measure the concentration of the implanted Si in various depths in the Au foils. Rutherford Backscattering Spectrometry (RBS) was also used as a complementary technique to probe for Au . SEM pictures indicate that a eutectic structure was induced in the implanted samples. A pure gold piece is put on top of the region where the silicon has been incorporated by diffusion and the two pieces were simply reheated at 400°C. After a few minutes, the two pieces were bonded, giving a perfect joint. SEM images of the joining region confirmed this situation by showing a clean soldered region.