bluuebunny/crossref_metadata_2025 huggingface dataset:
Functional variables associated with the clinical grade of dyspnoea in coal miners with pneumoconiosis and mild bronchial obstruction
Authors: Bauer T T , Schultze-Werninghaus G , Kollmeier J , Weber A , Eibel R , Lemke B , Schmidt E-W
Published: July 2002

OBJECTIVES

Dyspnoea is a common symptom in coal miners with pneumoconiosis. Among others, gas exchange disturbances due to airway obstruction or mismatch between ventilation and perfusion may be underlying mechanisms. The validation of dyspnoea by the degree of airway obstruction is controversial, because the extent of airway obstruction often does not correlate with the clinical grade of breathlessness.

METHODS

The association was investigated between breathlessness (self reported, on a six point scale) and indices of submaximal spiroergometry in 66 coal workers with radiographically confirmed pneumoconiosis (International Labour Organisation (ILO) grade of profusion ⩾1/0, mean (SD) age 64 (5.5) years, mean (SD) forced expired volume in 1 second (FEV1) 77.5 (22.9) % predicted).

RESULTS

The clinical degree of breathlessness was independently associated with minute ventilation/oxygen consumption (V˙E/V˙O2) ratio (β 0.423, 95% confidence interval (95% CI) 0.18 to 0.67, p=0.001) and smoking (β 0.318, 95% CI 0.21 to 1.79, p=0.014) in a multiple linear regression analysis. The V˙E/V˙O2ratio (β 0.556, 95% CI 0.20 to 0.90, p=0.003) was also the best predictor of breathlessness when only coal miners with airway obstruction (FEV1< 80% predicted) were analyzed.

CONCLUSION

TheV˙E/V˙O2ratio as a measurement of mismatch between ventilation and perfusion predicted the clinical grade of breathlessness better than measurements of bronchial obstruction at rest in coal workers with pneumoconiosis.
Organisational downsizing and musculoskeletal problems in employees: a prospective study
Authors: Kivimäki M , Vahtera J , Ferrie J E , Hemingway H , Pentti J
Published: July 2002

OBJECTIVES

To study the association between organisational downsizing and subsequent musculoskeletal problems in employees and to determine the association with changes in psychosocial and behavioural risk factors.

METHODS

Participants were 764 municipal employees working in Raisio, Finland before and after an organisational downsizing carried out between 1991 and 1993. The outcome measures were self reports of severity and sites of musculoskeletal pain at the end of 1993 and medically certified musculoskeletal sickness absence for 1993–5. The contribution of changes in psychosocial work characteristics and health related behaviour between the 1990 and 1993 surveys was assessed by adjustment.

RESULTS

After adjustment for age, sex, and income, the odds ratio (OR) for severe musculoskeletal pain between major and minor downsizing and the corresponding rate ratios for musculoskeletal sickness absence were 2.59 (95% confidence interval (95% CI) 1.5 to 4.5) and 5.50 (3.6 to 7.6), respectively. Differences between the mean number of sites of pain after major and minor downsizing was 0.99 (0.4 to 1.6). The largest contribution from changes in work characteristics and health related behaviour to the association between downsizing and musculoskeletal problems was from increases in physical demands, particularly in women and low income employees. Additional contributory factors were reduction of skill discretion (relative to musculoskeletal pain) and job insecurity. The results were little different when analyses were confined to initially healthy participants.

CONCLUSIONS

Downsizing is a risk factor for musculoskeletal problems among those who remain in employment. Much of this risk is attributable to increased physical demands, but adverse changes in other psychosocial factors may also play a part.
Relation between exposure to asbestos and smoking jointly and the risk of lung cancer
Authors: Lee P N
Published: July 2002

OBJECTIVES

To review evidence about the joint relation of exposure to asbestos and smoking on the risk of lung cancer to answer three questions: (1) does asbestos increase risk in non-smokers; (2) are the data consistent with an additive model; and (3) are the data consistent with a multiplicative model?

METHODS

Analysis of 23 studies reporting epidemiological evidence on the joint relation. Comparison of risk of lung cancer in subjects unexposed to asbestos or smoking, exposed to asbestos only, to smoking only, or to both. Estimation of the relative risk associated with asbestos exposure in non-smokers and of statistics testing for additivity and multiplicativity of risk.

RESULTS

Eight of the 23 studies provided insufficient data on the risk of lung cancer in non-smokers to test for possible effects of asbestos. Asbestos exposure was associated with a significantly (p<0.05) increased risk in non-smokers in six of the remaining studies and with a moderately increased, but not significant, increase in a further six. In two of the three studies that found no increase, asbestos exposure was insufficient to increase risks in smokers. In 30 of 31 data sets analysed, risk in the combined exposure group was greater than predicted by the additive model. There was no overall departure from the multiplicative model, the proportional increase in risk of lung cancer with exposure to asbestos being estimated as 0.90 (95% confidence interval (95% CI) 0.67 to 1.20) times higher in smokers than non-smokers. For two studies significant (p<0.05) departures from a multiplicative relation were found in some, but not all, analyses. Reasons are presented why these may not indicate true model discrepancies.

CONCLUSIONS

Asbestos exposure multiplies risk of lung cancer by a similar factor in non-smokers and smokers. The extent to which it multiplies risk varies between studies, no doubt depending on the type of asbestos involved, and the nature, extent, and duration of exposure.
What happens to the manuscripts that have not been accepted for publication inOccupational and Environmental Medicine?
Authors: Nemery B
Published: July 2002

OBJECTIVES

To evaluate the fate of manuscripts rejected byOccupational and Environmental Medicine(OEM).

METHODS

A Medline search was conducted, up to March 2001, to find out whether and where articles submitted toOEMin 1995, 1996, and 1997, but not accepted for publication, were published. The articles were matched by authors and title, sometimes using the abstract to help decide whether the published article was the one that had been previously submitted toOEM.

RESULTS

Out of 405 manuscripts rejected (44% of those submitted), 218 articles (54%) were traced in 72 different journals, with more than half being published in seven other major journals dealing with occupational and environmental health (rather than in specialty journals). Most papers were published within 2 years of their initial submission toOEM. Only a small proportion (10%) were published in a journal with a higher impact factor thanOEM(1.96 in 1999).

CONCLUSION

More than half the articles rejected byOEMfound their way into the scientific literature covered by Medline. This figure is comparable with the few available data from other journals. It would be interesting to know the fate of articles published byOEMbefore they were submitted to our journal.
Risk of birth defects by parental occupational exposure to 50 Hz electromagnetic fields: a population based study
Authors: Blaasaas K G , Tynes T , Irgens Å , Lie R T
Published: July 2002

Objectives: To study the risk of birth defects by parental occupational exposure to 50 Hz electromagnetic fields.

Methods: The Medical Birth Registry of Norway was linked with census data on parental occupation. An expert panel constructed a job exposure matrix of parental occupational exposure to 50 Hz magnetic fields. Exposure to magnetic fields was estimated by combining branch and occupation into one of three exposure levels: <4 hours, 4–24 hours, and >24 hours/week above approximately 0.1 μT. Risks of 24 categories of birth defects were compared across exposure levels. Out of all 1.6 million births in Norway in the period 1967–95, 836 475 and 1 290 298 births had information on maternal and paternal exposure, respectively. Analyses were based on tests for trend and were adjusted for parents' educational level, place of birth, maternal age, and year of birth.

Results: The total risk of birth defects was not associated with parental exposure. Maternal exposure was associated with increased risks of spina bifida (p=0.04) and clubfoot (p=0.04). A negative association was found for isolated cleft palate (p=0.01). Paternal exposure was associated with increased risks of anencephaly (p=0.01) and a category of “other defects” (p=0.02).

Conclusion: The present study gives an indication of an association between selected disorders of the central nervous system and parental exposure to 50 Hz magnetic fields. Given the crude exposure assessment, lack of comparable studies, and the high number of outcomes considered, the results should be interpreted with caution.
Respiratory symptoms, lung function, and nasal cellularity in Indonesian wood workers: a dose-response analysis
Authors: Borm P J A , Jetten M , Hidayat S , van de Burgh N , Leunissen P , Kant I , Houba R , Soeprapto H
Published: July 2002

Objectives: It was hypothesised that inflammation plays a dominant part in the respiratory effects of exposure to wood dust. The purpose of this study was to relate the nasal inflammatory responses of workers exposed to meranti wood dust to (a) levels of exposure, (b) respiratory symptoms and (c) respiratory function.

Methods: A cross sectional study was carried out in 1997 in a woodworking plant that used mainly meranti, among 982 workers exposed to different concentrations of wood dust. Personal sampling (n=243) of inhalable dust measurements indicated mean exposure in specific jobs, and enabled classification of 930 workers in three exposure classes (<2, 2–5, and >5 mg/m3) based on job title. Questionnaires were used to screen respiratory symptoms in the entire population. Lung function was measured with two different techniques, conventional flow-volume curves and the forced oscillation technique. Nasal lavage was done to assess inflammation in the upper respiratory tract.

Results: A negative trend between years of employment and most flow-volume variables was found in men, but not in women workers. Current exposure, however, was not related to spirometric outcomes, respiratory symptoms, or nasal cellularity. Some impedance variables were related to current exposure but also with better function at higher exposure.

Conclusions: Exposure to meranti wood dust did not cause an inflammation in the upper respiratory tract nor an increase of respiratory symptoms or decrease of lung function. These data do not corroborate the hypothesis that inflammation plays a part in airway obstruction induced by wood dust.
Out of hours management of occupational exposures to blood and body fluids in healthcare staff
Authors: Patel D , Gawthrop M , Snashall D , Madan I
Published: July 2002

Aims:To assess and compare the out of hours and in hours management of occupational blood and body fluid exposures in a London teaching hospital.

Methods:The occupational health and accident and emergency records of individuals presenting with occupational body fluid exposures over a six month period at a London teaching hospital were analysed retrospectively. Main outcome measures were the completeness of records, and the appropriate management of body fluid exposures using the Department of Health guidelines as the gold standard.

Results:A total of 177 body fluid exposures were reported; 109 (61.58%) were initially assessed in the occupational health department, and 68 (38.42%) in the accident and emergency department. Of those originally assessed in the accident and emergency department, only 21 (30.88%) attended the occupational health department for follow up. Occupational health staff were more consistent in assessing and managing exposures, and in a higher proportion of cases gave more appropriate advice on post-exposure prophylaxis (PEP) against hepatitis B and HIV. Of the 11 individuals prescribed HIV PEP (all by accident and emergency staff), only three subsequently attended occupational health for follow up. In all three cases therapy was discontinued, as the source was HIV negative or the exposure low risk.

Conclusions:Out of hours management of occupational body fluid exposures, particularly the prescribing of HIV PEP, was inconsistent with in hours practice. This may also be the case in other large inner city hospitals offering a similar service.
Unexplained hypokalaemia and metabolic alkalosis
Authors: Devendra D , Rowe P A
Published: July 2002

A 23 year old girl was admitted to the medical admission unit with a three month history of malaise and generalised muscle cramps. Her general practitioner performed routine biochemistry and had revealed a potassium concentration of 2.0 mmol/l. She was investigated four years before for a similar electrolyte disturbance which was found to be inconclusive. She was currently taking the combined oral contraceptive pill. There was no history of diarrhoea or vomiting. There was no family history of endocrine disease. On examination the patient appeared well, her body mass index was 19, and her blood pressure was 118/70 mm Hg. She was euvolaemic clinically. She had no evidence of postural hypotension nor did she have any peripheral oedema. Her skin turgor was normal.
Systemic cholesterol crystal embolisation with pulmonary involvement: a fatal combination after coronary angiography
Authors: Walton T J , Samani N J , Andrews R
Published: July 2002

Cholesterol crystal embolisation (CCE) is a rare but serious complication of invasive arterial procedures associated with a high mortality, and is a condition that medical staff undertaking invasive vascular procedures should be aware of. It is manifest as a multisystem disorder commonly involving the kidneys and peripheries, but rarely affecting the lungs. A case of fatal CCE with pulmonary involvement is reported, and similar published case reports are reviewed. The pathogenesis of lung involvement in CCE is unclear, but the combination is reported to be invariably fatal.
Synthèse géoélectrique appliquée à la caractérisation des contacts entre nappes de charriage et son apport hydrogéologique dans la Plaine de Tamlouka « Région de Guelma, Est Algérien »
Authors: Hemila Mohammed Laid , Kowalski Waclaw Marian
Published: July 2002

The geological work undertaken in the north oriental regions of Algeria have considered the plain of Tamlouka, region of Guelma, as a meeting crossroad of the three structural domains of Sellaoua, Néritic Constantine, and Tellian. The tectonic contact between the overthrust sheets is hidden by a thick alluvium cover and has remained undetermined in spite of recent exploration attempts by a geoelectric method. In this paper, we present the results of our work on the reinterpretation of the basic geoelectric data, which were founded on the calibration principle, considering all the geological information available from outcrops and cuttings of recent drill holes. Twenty-nine geoelectric profiles and three maps are drawn in which (i) the facies and geometry of the Mio-Plio-Quaternary fill are much better identified; (ii) an underground synthesis of the relation between the tectonic units is proposed after an inventory of the subsurface formations; and (iii) the ground-water potential in the plain is much better assessed.Key words: geoelectric method, geometry, overthrust sheets, ground-water potential, Tamlouka, Algeria.
No change in dopamine D1 receptor in vivo binding in rats after sub-chronic haloperidol treatment
Authors: Sanci Vito , Houle Sylvain , DaSilva Jean N
Published: July 2002

A frequent side effect in the long-term treatment of schizophrenia with the dopamine D2 antagonist haloperidol (HAL) is the appearance of tardive dyskinesia or, in animals, of repetitive involuntary vacuous chewing movements (VCMs). In rats, chronic HAL-induced or D1 receptor-stimulated VCMs are suppressed by D1 antagonists, suggesting that this behavioral supersensitivity is mediated by D1 receptors. The goal of this study was to investigate in vivo the possible relationship between D1 receptor binding and D1-mediated behavioral supersensitivity, after sub-chronic HAL treatments. D1 agonist R-SKF 82957 and antagonist SCH 23390, both labeled with carbon-11, were used to assess in vivo D1 receptor binding. Rats were treated with HAL (1.5 mg/kg, i.p.) or vehicle for 21 days, followed by a 4 day washout period. No significant difference was found in the regional brain binding of either radioligand. D1 receptor-mediated behaviors including VCMs, grooming, and rearing were measured in control or HAL-treated rats. VCMs were significantly increased in HAL-treated rats, suggesting D1 receptor stimulation and possibly receptor supersensitivity. This study failed to link the purported D1 receptor-mediated behaviors with in vivo receptor binding measures of R-[11C]SKF 82957 or [11C]SCH 23390 in rat brain regions.Key words: typical neuroleptics, vacuous chewing movements, behavioral D1 supersensitivity, tardive dyskinesia, positron emission tomography.
Tissue-specific extravasation of albumin-bound Evans blue in hypothermic and rewarmed rats
Authors: Matthew Candace B , Sils Ingrid V , Bastille Amy M
Published: July 2002

The effects of hypothermia and rewarming on endothelial integrity were examined in intestines, kidney, heart, gastrocnemius muscle, liver, spleen, and brain by measuring albumin-bound Evans blue loss from the vasculature. Ten groups of twelve rats, normothermic with no pentobarbital, normothermic sampled at 2, 3, or 4 h after pentobarbital, hypothermic to 20, 25, or 30°C, and rewarmed from 20, 25, or 30°C, were cooled in copper coils through which water circulated. Hypothermic rats were cooled to the desired core temperature and maintained there for 1 h; rewarmed rats were cooled to the same core temperatures, maintained there for 1 h, and then rewarmed. Following Evans blue administration, animals were euthanized with methoxyflurane, tissues removed, and Evans blue extracted. Because hypothermia and rewarming significantly decrease blood flow, organ-specific flow rates for hypothermic and rewarmed tissues were used to predict extravasation. Hypothermia decreased extravasation in tissues with continuous endothelium (brain, muscle) and increased it in tissues with discontinuous endothelium (liver, lung, spleen). All tissues exhibited significant (p < 0.05) differences from normothermic controls. These differences are attributed to a combination of anesthesia, flow, and (or) change in endothelial permeability, suggesting that appropriate choice of organ and temperature would facilitate testing pharmacological means of promoting return to normal perfusion.Key words: hypothermia, rewarming, vascular permeability, Evans blue, endothelium, anesthesia, thermoregulation.
Comparative feeding strategies and dietary plasticity of the sympatric cobras Naja melanoleuca and Naja nigricollis in three diverging Afrotropical habitats
Authors: Luiselli Luca , Angelici Francesco M , Akani Godfrey C
Published: July 2002

Two cobra species are found in the forest block of southern Nigeria (West Africa). However, whereas the one species, the spitting cobra (Naja nigricollis), is often found in strongly altered habitats (including suburban areas), the other, the black forest cobra (Naja melanoleuca), is a typical forest species that is currently subject to a rapid decrease in population abundance because of intensive forest alteration and landscape modification in this part of Africa. We studied whether the body sizes, diets, and feeding strategies of these two species changed in relation to habitat type, and whether the ecological success of the one species versus the other in altered habitats depends upon greater dietary flexibility in prey type or prey size. Therefore, we divided our cobra records into three habitat categories: (1) suburbia, (2) plantationforest mosaic, and (3) mature forest. We observed that sexual size dimorphism was minor in both species and in all habitat types, and that intersexual differences in prey composition and prey size were also minor. Nevertheless, there was a remarkable ontogenetic change in taxonomic composition of the diet for one species (N. nigricollis, with juveniles taking almost exclusively lizards and adults taking small mammals, birds, and lizards) but not the other. Remarkably, the species that is less adapted to life in suburban areas showed a reduction in mean body size from the forest to suburbia, which may also indicate suboptimal adaptation to strongly altered habitats. Prey size was similar for the two species and in the three habitat types, and the relationships between prey size and predator size were similar. Thus, it seems unlikely that flexibility in prey-size patterns explains the greater colonizing success of N. nigricollis. Nevertheless, and although both species exhibited remarkable dietary flexibility, leading them to prey upon homeotherms as well as heterotherms and upon terrestrial as well as arboreal and even aquatic prey, there were important interspecific differences in prey composition that may explain the ecological success of N. nigricollis. The success of N. nigricollis likely lies not in dietary flexibility but in the consistency with which its juveniles prey upon a single prey type (lizards, mainly Agama agama) that is so abundant in nearly every altered habitat in Nigeria and is a virtually unlimited food resource for young N. nigricollis. However, adults of this species also forage frequently upon commensal rodents and poultry, which may also help it to colonize man-made habitats.
Effects of litter size on pup defence and weaning success of neighbouring bank vole females
Authors: Jonsson Pernilla , Agrell Jep , Koskela Esa , Mappes Tapio
Published: July 2002

Reproductive success of territorial female mammals depends partly on their capability to defend their young from conspecific intruders. However, how this is related to the characteristics of females and their litter sizes is largely unknown. The defence activity of 25 female bank voles (Clethrionomys glareolus) in relation to the number of offspring was studied in a behavioural arena by manipulating litter sizes (2 pups or +2 pups). Infanticidal male bank voles were used as intruderspredators. Moreover, the weaning success (weaned at least one offspring or none) of 15 pairs of neighbouring females was investigated in a large indoor runway system. In each pair of females, the litter size of one female was reduced (2 pups) and the litter size of the other enlarged (+2 pups). Defence activity of females increased with the number of offspring and the mother's size. However, weaning success of neighbours was related only to their body mass, and litter-size manipulation did not affect weaning success. Present results indicate that, although bank vole females increase their defence intensity with an increase in the number of pups, the weaning success of neighbouring females may be primarily determined by their size and dominance rank.
PHASE SPACE PROPERTIES OF CHARGED FIELDS IN THEORIES OF LOCAL OBSERVABLES
Authors: BUCHHOLZ D. , D’ANTONI C.
Published: July 2002

Within the setting of algebraic quantum field theory a relation between phase-space properties of observables and charged fields is established. These properties are expressed in terms of compactness and nuclearity conditions which are the basis for the characterization of theories with physically reasonable causal and thermal features. Relevant concepts and results of phase space analysis in algebraic quantum field theory are reviewed and the underlying ideas are outlined.
Supergeometry and Quantum Field Theory, or: What is a Classical Configuration?
Authors: Schmitt T.
Published: July 2002

We discuss the conceptual difficulties connected with the anticommutativity of classical fermion fields, and we argue that the "space" of all classical configurations of a model with such fields should be described as an infinite-dimensional supermanifold M. We discuss the two main approaches to supermanifolds, and we examine the reasons why many physicists tend to prefer the Rogers approach although the Berezin–Kostant–Leites approach is the more fundamental one. We develop the infinite-dimensional variant of the latter, and we show that the superfunctionals considered in [44] are nothing but superfunctions on M. We propose a programme for future mathematical work, which applies to any classical field model with fermion fields. A part of this programme will be implemented in the successor paper [45].
PRYM VARIETIES AND THE INFINITE GRASSMANNIAN
Authors: MARTÍN FRANCISCO J. PLAZA
Published: July 2002

In this paper we study Prym varieties and their moduli space using the well-known techniques of the infinite Grassmannian. There are three main results of this paper: a new definition of the BKP hierarchy over an arbitrary base field (that generalizes the classical one over [Formula: see text]); a characterization of Prym varieties in terms of dynamical systems, and explicit equations for the moduli space of (certain) Prym varieties. For all of these problems the language of the infinte Grassmannian, in its algebro-geometric version, allows us to deal with these problems from the same point of view.
EQUIVALENCE BETWEEN THE FLR TIME DEPENDENT PERCOLATION MODEL AND THE NEWMAN–ZIFF ALGORITHM
Authors: de FREITAS JOAQUIM E. , LUCENA LIACIR S.
Published: July 2002

We compare the results of a very efficient algorithm that we have proposed to study the time evolution of percolation clusters when the occupation probability swept through the critical value in the same sample and in a single run with another algorithm proposed by Newman and Ziff to allow fast calculations of the standard percolation model. Both have a complexity per site that is roughly independent of the size of the system. Our results show that for the derivative threshold distribution, the results ( exponent = 1.8 ± 0.2) are closer to Wester while for the cumulative distribution ( exponent = 1.5 ± 0.1), they are closer to Newman and Ziff.
ON A VARIABLE-COEFFICIENT MODIFIED KP EQUATION AND A GENERALIZED VARIABLE-COEFFICIENT KP EQUATION WITH COMPUTERIZED SYMBOLIC COMPUTATION
Authors: GAO YI-TIAN , TIAN BO
Published: July 2002

The variable-coefficient nonlinear evolution equations, although realistically modeling various mechanical and physical situations, often cause some well-known powerful methods not to work efficiently. In this paper, we extend the power of the generalized hyperbolic-function method, which is based on the computerized symbolic computation, to a variable-coefficient modified Kadomtsev–Petviashvili (KP) equation and a generalized variable-coefficient KP equation. New exact analytic solutions thus come out.
QUANTUM FIELD THEORY AND COMPUTATIONAL PARADIGMS
Authors: KRISHNAMURTHY E. V. , KRISHNAMURTHY VIKRAM
Published: July 2002

We introduce the basic theory of quantization of radiation field in quantum physics and explain how it relates to the theory of recursive functions in computer science. We outline the basic differences between quantum mechanics (QM) and quantum field theory (QFT) and explain why QFT is better suited for a computational paradigm — based on algorithmic requirement, countably infinite degrees of freedom and the creation of macroscopic output objects. The quanta of the radiation field correspond to the non-negative integers and the harmonic oscillator spectra correspond to the recursive computation — with the creation and annihilation operators, respectively, playing the same role as the successor and predecessor in computability theory. Accordingly, this approach relates the classical computational model and the quantum physical model more directly than the Turing machine approach used earlier. Also, the application of Lambda calculus formalism and the associated denotational semantics (that is widely used in the classical computational paradigm involving recursive functions) for applications to computational paradigm based on quantum field theory is described. Finally, we explain where QFT and conventional paradigm depart from each other, and examine the concept of fixed points, phase transitions, programmability, emergent computation and related open problems.
ODD-FLAVOR HYBRID MONTE CARLO ALGORITHM FOR LATTICE QCD
Authors: TAKAISHI TETSUYA , de FORCRAND PHILIPPE
Published: July 2002

We discuss hybrid Monte Carlo algorithms for odd-flavor lattice QCD simulations. The algorithms include a polynomial approximation, which enables us to simulate odd-flavor QCD in the framework of the hybrid Monte Carlo algorithm. In order to make the algorithms exact, the correction factor to the polynomial approximation is also included in an economical, stochastic way. We test the algorithms for nf = 1, 1 + 1 and 2 + 1 flavors and compare results with other algorithms.
HOLOGRAPHIC ENTROPY ON THE BRANE IN de SITTER SCHWARZSCHILD SPACE
Authors: OGUSHI SACHIKO
Published: July 2002

The relationship between the entropy of de Sitter (dS) Schwarzschild space and that of the CFT, which lives on the brane, is discussed by using Friedmann–Robertson–Walker (FRW) equations and Cardy–Verlinde formula. The cosmological constant appears on the brane with time-like metric in dS Schwarzschild background. On the other hand, in case of the brane with space-like metric in dS Schwarzschild background, the cosmological constant of the brane does not appear because we can choose brane tension to cancel it. We show that when the brane crosses the horizon of dS Schwarzschild black hole, both for time-like and space-like cases, the entropy of the CFT exactly agrees with the black hole entropy of five-dimensional dS background as it happens in the AdS/CFT correspondence.
CLASSIFICATION OF POISSON–LIE T-DUAL MODELS WITH TWO-DIMENSIONAL TARGETS
Authors: HLAVATÝ LADISLAV , ŠNOBL LIBOR
Published: July 2002

Four-dimensional Manin triples and Drinfeld doubles are classified and the corresponding two-dimensional Poisson–Lie T-dual sigma models on them are constructed. The simplest example of a Drinfeld double allowing decomposition into two nontrivially different Manin triples is presented.
CANONICAL DISCRETIZATION I: DISCRETE FACES OF (AN)HARMONIC OSCILLATOR
Authors: TURBINER ALEXANDER
Published: July 2002

A certain notion of canonical equivalence in quantum mechanics is proposed. It is used to relate quantal systems with discrete ones. Discrete systems canonically equivalent to the celebrated harmonic oscillator as well as the quartic and the quasiexactly-solvable anharmonic oscillators are found. They can be viewed as a translation-covariant discretization of the (an)harmonic oscillator preserving isospectrality. The notion of the q-deformation of the canonical equivalence leading to a dilatation-covariant discretization preserving polynomiality of eigenfunctions is also presented.
AXIAL ANOMALY IN NONCOMMUTATIVE QED ON R4
Authors: ARDALAN FARHAD , SADOOGHI NÉDA
Published: July 2002

The axial anomaly of the noncommutative U(1) gauge theory is calculated by a number of methods and compared with the commutative one. It is found to be given by the corresponding Chern class.
ON THE EQUIVALENCE OF THE BUCHDAHL AND THE JANIS–NEWMAN–WINNICOUR SOLUTIONS
Authors: BHADRA A. , NANDI K. K.
Published: July 2002

We comment that the static and spherically symmetric solutions to the Einstein-minimally coupled scalar field theory as obtained independently by Buchdahl and Janis–Newman–Winicour (JNW) are the same. Since it is already known that JNW and Wyman solutions are not different,1 therefore we conclude that Buchdahl, JNW and Wyman solutions are the same.
PHYSICAL RESULTS FROM PARTIALLY QUENCHED SIMULATIONS
Authors: SHARPE STEPHEN R. , SHORESH NOAM
Published: July 2002

We describe how one can use chiral perturbation theory to obtain results for physical quantities, such as quark masses, using partially quenched simulations.
COMPARISON OF THE NMR AND NEUTRON SCATTERING EXPERIMENTS ON CUPRATES WITH NONMAGNETIC IMPURITIES
Authors: BULUT N. , YAZ U.
Published: July 2002

The NMR and neutron scattering experiments on YBa 2 Cu 3 O 7 with Li and Zn impurities are compared using a simple framework exhibiting short-range antiferromagnetic correlations. The model parameters are determined by fitting the NMR rate [Formula: see text] of the pure system, and the effective impurity potential is approximated by a static extended form. The results of the calculations are compared with the experimental data, and their implications are discussed.
PRESSURE EFFECT AND SPECIFIC HEAT OF RBa2Cu3Ox AT DISTINCT CHARGE CARRIER CONCENTRATIONS: POSSIBLE INFLUENCE OF STRIPES
Authors: SCHLACHTER S. I. , TUTSCH U. , FIETZ W. H. , WEISS K.-P. , LEIBROCK H. , GRUBE K. , WOLF Th. , OBST B. , SCHWEISS P. , WÜHL H.
Published: July 2002

In YBa 2 Cu 3 O x, distinct features are found in the pressure dependence of the transition temperature, d T c / d p, and in ΔCp· T c , where ΔCp is the jump in the specific heat at T c : d T c / d p becomes zero when ΔCp· T c is maximal, whereas d T c / d p has a peak at lower oxygen contents where ΔCp· T c vanishes. Substituting Nd for Y and doping with Ca leads to a shift of these specific oxygen contents, since oxygen order and hole doping by Ca influences the hole content n h in the CuO 2 planes. Calculating n h from the parabolic T c (n h ) behavior, the features coalesce for all samples at n h ≈0.11 and n h ≈0.175, irrespective of substitution and doping. Hence, this behavior seems to reflect an intrinsic property of the CuO 2 planes. Analyzing our results we obtain different mechanisms in three doping regions: T c changes in the optimally doped and overdoped region are mainly caused by charge transfer. In the slightly underdoped region an increasing contribution to d T c / d p is obtained when well ordered CuO chain fragments serve as pinning centers for stripes. This behavior is supported by our results on Zn doped NdBa 2 Cu 3 O x and is responsible for the well known d T c / d p peak observed in YBa 2 Cu 3 O x at x≈6.7. Going to a hole content below n h ≈0.11 our results point to a crossover from an underdoped superconductor to a doped antiferromagnet, changing completely the physics of these materials.
PROJECTED SO(5) HAMILTONIAN FOR CUPRATES AND ITS APPLICATIONS
Authors: AUERBACH ASSA , ALTMAN EHUD
Published: July 2002

The projected SO(5) (pSO(5)) Hamiltonian incorporates the quantum spin and superconducting fluctuations of underdoped cuprates in terms of four bosons moving on a coarse grained lattice. A simple mean field approximation can explain some key features of the experimental phase diagram: (i) The Mott transition between antiferromagnet and superconductor, (ii) the increase of T c and superfluid stiffness with hole concentration x and (iii) the increase of antiferromagnetic resonance energy as [Formula: see text] in the superconducting phase. We apply this theory to explain the "two gaps" problem in underdoped cuprate SNS junctions. In particular we explain the sharp subgap Andreev peaks of the differential resistance, as signatures of the antiferromagnetic resonance (the magnon mass gap). A critical test of this theory is proposed. The tunneling charge, as measured by shot noise, should change by increments of ΔQ=2e at the Andreev peaks, rather than by ΔQ=e as in conventional superconductors.
NOVEL APPROACH TO FANO RESONANCE OF EXCITONS IN SEMICONDUCTOR QUANTUM WELLS
Authors: HINO KEN-ICH
Published: July 2002

A new approach to Fano resonance of excitons in quantum-confined systems is presented based on the 4×4 Luttinger Hamiltonian. This method, consisting of two stages, namely, the adiabatic expansion and the R-matrix propagation, allows to implement high-resolution calculations of Fano profiles having natural spectral widths without any empirical broadening parameter which is indispensable in conventional methods. As a demonstration, this approach is applied to Fano resonance of an exciton in a wide quantum well, where hole-subband mixing is substantial and a complicated energy-structure is expected. Resulting spectral profiles show rich fine structures due to overlap with adjacent resonances and the hole-subband mixing.
GROWTH AND STRUCTURAL PROPERTIES OF GaN FILMS ON FLAT AND VICINAL SiC(0001) SUBSTRATES
Authors: XIE M. H. , CHEUNG S. H. , ZHENG L. X. , TONG S. Y. , ZHANG B. S. , YANG H.
Published: July 2002

Initial stage GaN growth by molecular-beam (MBE) on SiC (0001) substrate is followed by in situ scanning tunneling microscopy. Comparison is made between growth on nominally flat and vicinal substrate surfaces and the results reveal characteristic differences between the two. Ex situ transmission electron microscopy (TEM) and X-ray diffraction (XRD) rocking curve measurements of the films show lower density of defects and better structural quality of the vicinal film. We suggest the improved structural quality of the vicinal film is related to the characteristic difference in its initial stage nucleation and coalescence processes than that of the flat film.
FORMATION OF THE BAND GAP OF CdS THIN FILMS GROWTH BY DIFFERENT TECHNIQUES
Authors: OLIVA A. I. , SOLÍS-CANTO O. , CASTRO-RODRÍGUEZ R. , QUINTANA P.
Published: July 2002

We studied the formation of the band gap on CdS thin films deposited on glass substrates by chemical bath deposition (CBD) and close spaced sublimation (CSS) techniques. In order to obtain the first stages of films growth, we used small deposition times for both methods. Films growth by CBD were prepared by two modalities on the bath agitation: magnetic agitation with a magnetic stirrer, and a new proposal based on ultrasonic vibration. Morphological, structural, and optical results were obtained on films. Values of the band gap energy obtained by the absorption method, are agree with the values reported in the literature, but squared absorption coefficient vs. energy curves, showed differences between them. An explanation on this behavior with the optical window effects, the surface roughness, the structural results, the films thickness, and the growth technique is given. CBD technique with ultrasonic vibration produces films with more cleaner surfaces and better optical properties.
INFLUENCE OF HELIUM CO-IMPLANTATION ON THE FORMATION OF GOLD NANOCLUSTERS IN LITHIUM NIOBATE
Authors: KLING A. , DA SILVA M. F. , SOARES J. C. , FICHTNER P. F. P. , AMARAL L. , ZAWISLAK F. C.
Published: July 2002

Single crystalline lithium niobate samples cut perpendicular to the [Formula: see text]-direction (Y-cut) have been implanted with 1 × 1016 cm -2 He + ions of 20 KeV energy. He -implanted and virgin samples were implanted with Au + ions at energies of 50 KeV or 800 KeV to the fluences of 5 × 1015 cm -2 or 1 × 1016 cm -2, respectively. In the first case separated, and in the latter, overlapping profiles of Au and He are created. The effects of annealing on the microstructure of the samples were investigated in the range from 270°C to 800°C by means of Rutherford backscattering spectrometry and transmission electron microscopy. Indications of an influence of He + co-implantation on the Au cluster structure have been observed in samples with overlaping profiles after annealing at 800°C.
ELECTRONIC STRUCTURE OF SIX PHASES OF C3N4: A THEORETICAL APPROACH
Authors: MOLINA B. , SANSORES L. E.
Published: July 2002

A systematic study of the structural properties and electronic structure of six phases of C3N4 is presented. The phases under study are the β, α, cubic, pseudocubic and two graphitic with different space group. The structural analysis shows that only in β and graphitic phases the N atoms behave in a pure sp2 configuration. In the other phases, α, cubic and pseudocubic, the N with its 3 C neighbors form a pyramid. The band structure for each of the six phases is presented indicating with β, α and cubic phases have an indirect gap while the pseudocubic and the two graphitic phases have a direct gap. Also charge density contours are presented and analyzed.
IMAGE-PROCESSING PROJECTS FOR AN ALGORITHMS COURSE
Authors: FINK EUGENE , HEATH MICHAEL
Published: July 2002

Courses on algorithm analysis often include little programming, and do not emphasize application of advanced techniques to practical problems. On the other hand, students usually prefer hands-on learning, and may lack motivation to study theory.

We augmented an algorithms course with a series of programming tasks, which involved application of the course material to image processing. These tasks motivated the students, and led to better understanding and retention of theoretical material. They also enabled the students to learn the basics of representing and manipulating images, along with the algorithm theory.
THE 1:2 MODE INTERACTION IN RAYLEIGH–BÉNARD CONVECTION WITH AND WITHOUT BOUSSINESQ SYMMETRY
Authors: PRAT JOANA , MERCADER ISABEL , KNOBLOCH EDGAR
Published: July 2002

Nonlinear two-dimensional Rayleigh–Bénard convection with periodic boundary conditions in the horizontal is studied for spatial periods near the 1:2 steady state mode interaction. The boundary conditions at the bottom are no-slip, and convection is driven by a fixed imposed temperature difference across the layer. Homotopic continuation is used to continue the boundary conditions at the top from no-slip (β=0) to stress-free (β=1). When β=0 and non-Boussinesq effects are absent the system has midplane reflection symmetry and the 1:2 resonance is weak. When β=1 this symmetry is strongly broken and the resonance is strong. The transition between these two cases is explored for two Prandtl numbers, σ=10 and σ=0.1, representing behavior typical of large and low Prandtl numbers, respectively.
CIRCULAR CHAOS GAME REPRESENTATION OF 1-D CHAOS AND ITS RELATION TO THE COMPLEX WEIERSTRASS FUNCTION
Authors: TSUCHIYA TAKASHI
Published: July 2002

Barnsley's chaos game which is originally played on a triangular field is generalized to a circular field and is used to visualize one-dimensional (1-D) fully developed chaos. It is shown that when the 1-D map used is the shift map or its extension (the r-adic map) the game point is exactly represented by the complex Weierstrass function.
ON RANK, ROOT AND EQUATIONS IN FREE GROUPS
Authors: ROSENMANN AMNON
Published: July 2002

Let h1, h2,… be a sequence of elements in a free group and let H be the subgroup they generate. Let H′ be the subgroup generated by w1, w2, …, where each wi is a word in hi and possibly other hj, such that the associated directed graph has the finite paths property. We show that rank H′≥ rank H. As a corollary we get that [Formula: see text], where [Formula: see text] is the subgroup generated by the roots of the elements in H. If H0 is finitely generated and the sequence of subgroups H0, H1, H2, … satisfies [Formula: see text] then the sequence stabilizes, i.e. for some m, Hi=Hi+1 for every i≥ m. When applied to systems of equations in free groups, we give conditions on a transformation of the system such that the maximal rank of a solution (the inner rank) does not increase. In particular, we show that if in "Lyndon equation" [Formula: see text] the exponents ai satisfy gcd (a1,…,an)≠1 then the inner rank is ⌊ n/2⌋. The proofs are mostly elementary.
AUTOMATIC SEMIGROUPS WITH SUBSEMIGROUPS OF FINITE REES INDEX
Authors: HOFFMANN MICHAEL , THOMAS RICHARD M. , RUŠKUC NIK
Published: July 2002

The notion of automaticity has been widely studied in groups and some progress has been made in understanding this notion in the wider context of semigroups. The purpose of this paper is to study the connections between the automaticity of semigroups S and T where T is a subsemigroup of finite Rees index in S.
MALNORMALITY IS DECIDABLE IN FREE GROUPS
Authors: BAUMSLAG GILBERT , MYASNIKOV ALEXEI , REMESLENNIKOV VLADIMIR
Published: July 2002

We prove here that there is an algorithm whereby one can decide whether or not any finitely generated subgroup of a finitely generated free group is malnormal.
ASYMPTOTIC EXPANSION FOR DAMPED WAVE EQUATIONS WITH PERIODIC COEFFICIENTS
Authors: ORIVE R. , ZUAZUA E. , PAZOTO A. F.
Published: July 2002

We consider a linear dissipative wave equation in ℝN with periodic coefficients. By means of Bloch wave decomposition, we obtain an expansion of solutions as t→∞ and conclude that, in a first approximation, the solutions behave as the homogenized heat kernel.
APPROXIMATION BY THE FINITE VOLUME METHOD OF AN ELLIPTIC-PARABOLIC EQUATION ARISING IN ENVIRONMENTAL STUDIES
Authors: EYMARD R. , GALLOUËT T. , HERBIN R. , GUTNIC M. , HILHORST D.
Published: July 2002

We prove the convergence of a finite volume scheme for the Richards equation β(p)t- div (Λ(β(p))(∇p-ρg))=0 together with a Dirichlet boundary condition and an initial condition in a bounded domain Ω ×(0, T). We consider the hydraulic charge [Formula: see text] as the main unknown function so that no upwinding is necessary. The convergence proof is based on the strong convergence in L2 of the water saturation β(p), which one obtains by estimating differences of space and time translates and applying Kolmogorov's theorem. This implies the convergence in L2 of the approximate water mobility towards Λ(β(p)) as the time and mesh steps tend to 0, which in turn implies the convergence of the approximate pressure to a weak solution p of the continuous problem.
IMPROVED ACCURACY FOR LOCALLY ONE-DIMENSIONAL METHODS FOR PARABOLIC EQUATIONS
Authors: DOUGLAS JIM , KIM SEONGJAI
Published: July 2002

Classical alternating direction (AD) and fractional step (FS) methods for parabolic equations, based on some standard implicit time-stepping procedure such as Crank–Nicolson, can have errors associated with the AD or FS perturbations that are much larger than the errors associated with the underlying time-stepping procedure. We show that minor modifications in the AD and FS procedures can virtually eliminate the perturbation errors at an additional computational cost that is less than 10% of the cost of the original AD or FS method. Moreover, after these modifications, the AD and FS procedures produce identical approximations of the solution of the differential problem. It is also shown that the same perturbation of the Crank–Nicolson procedure can be obtained with AD and FS methods associated with the backward Euler time-stepping scheme. An application of the same concept is presented for second-order wave equations.
THE APPLICATION OF MACHINE LEARNING TOOLS TO THE VALIDATION OF AN AIR TRAFFIC CONTROL DOMAIN THEORY
Authors: WEST M. M. , McCLUSKEY T. L.
Published: July 2002

In this paper we describe a project (IMPRESS) in which machine learning (ML) tools were created and utilised for the validation of an Air Traffic Control domain theory written in first order logic. During the project, novel techniques were devised for the automated revision of general clause form theories using training examples. These techniques were combined in an algorithm which focused in on the parts of a theory which involve ordinal sorts, and applied geometrical revision operators to repair faulty component parts. While we illustrate the feasibility of applying ML to this area, we conclude that to be effective it must be focused to the application at hand, and used in mixed-initiative mode within a tools environment. The method is illustrated with experimental results obtained during the project.