bluuebunny/crossref_metadata_2025 huggingface dataset:
Increase in interleukin-6 and fibrinogen after exposure to dust in tunnel construction workers
Authors: Hilt B , Qvenild T , Holme J , Svendsen K , Ulvestad B
Published: July 2002

Objectives: To see if there is any change in blood concentrations of interleukin-6 (IL-6) and fibrinogen during a working shift in tunnel construction workers.

Methods: 12 Tunnel construction workers were followed up during a 24 hours period after returning from a 9 day work free period. The first blood sample was taken on Monday afternoon before starting the shift. Another was taken around midnight after 8 hours of work, and another the next afternoon after about 12 hours of rest. Exposure to respirable dust was measured by personal samplers.

Results: The exposure of the workers to respirable dust, in terms of an 8 hour time weighted average, varied between 0.3 and 1.9 mg/m3. For IL-6, there was an increase in the median serum concentration from 1.14 ng/l before starting the shift to 4.86 ng/l after 8 hours of work (p=0.002). For fibrinogen, there was an increase in the median concentration from 3.40 g/l before entering the shift to 3.70 g/l 24 hours later (p=0.044). There was a positive correlation between values of IL-6 at the end of the working shift and the fibrinogen concentrations the next afternoon (Pearson'sR=0.73, p=0.007). The observed increase in IL-6 was significant for both smokers and non-smokers.

Conclusion: The study shows an increase in both IL-6 and fibrinogen concentrations during a working shift for both smoking and non-smoking tunnel construction workers.
Incidence of asthma in female Swedish hairdressers
Authors: Albin M , Rylander L , Mikoczy Z , Lillienberg L , Dahlman Höglund A , Brisman J , Torén K , Meding B , Kronholm Diab K , Nielsen J
Published: July 2002

Objective: To investigate the risk of asthma in hairdressers.

Methods: The incidence of asthma was retrospectively estimated in a Swedish nationwide study including all female hairdressers certified from vocational schools from 1970 to 1995, and a stratified sample of women from the general population were referents. A postal questionnaire included questions on respiratory tract symptoms, atopy, smoking, working periods as a hairdresser, and number of specific hair treatments performed/week. Reported exposures were validated by occupational hygienists. Rate ratios of incidence (IRRs) of asthma were estimated by Poisson regression, adjusted for calendar year of observation, hay fever, smoking, and region of domicile.

Results: The crude incidences of asthma/1000 person-years were: 3.9 during active years as a hairdresser, 2.8 among the hairdressers when not working in the profession, and 3.1 among the referents. The corresponding IRR for being an active hairdresser compared with the referents was 1.3 (95% confidence interval (95% CI) 1.0 to 1.6). Moderate effects on risk of asthma were found both from hairdressing work (IRR=1.6 (1.1 to 2.2) among never-smokers) and from smoking (IRR=1.6 (1.2 to 2.2) among referents). However, the combined effect from hairdressing work and smoking (IRR=1.5 (1.0 to 2.1)) was less than expected (p=0.02). No effect modification by respiratory atopy was found. The hairdressers most often performing hair bleaching treatments (IRR=1.5 (0.7 to 3.0)) or using hair spray (IRR=1.4 (0.8 to 2.4)) had, compared with the most infrequent users, a slightly, but not significantly higher incidence of asthma. Exposure to persulphates in hair bleach was estimated to be 0.04–0.15 mg/m3during mixing of the powder. Reported average number of bleaching treatments agreed well with those performed according to a diary.

Conclusions: Active hairdressing work was associated with a moderately increased incidence of asthma among lifelong non-smokers. The results are moderately supportive, but not conclusive, of associations between asthma and exposure to hair bleach or hair spray.
Mortality from non-malignant respiratory disease in the fibreglass manufacturing industry
Authors: Chiazze L , Watkins D K , Fryar C , Fayerweather W , Kozono J , Biggs V
Published: July 2002

Objectives:To investigate the question of whether there is an association between workplace exposures and sociodemographic factors and mortality from non-malignant respiratory disease excluding influenza and pneumonia (NMRDxIP) among workers in a fibreglass wool manufacturing facility.

Methods:A case-control study with cases and controls derived from deaths recorded from the Kansas City plant in the Owens Corning mortality surveillance system. The cases are defined as decedents with NMRDxIP as the underlying cause of death. Matched, unadjusted odds ratios (ORs) were used to assess any association between NMRDxIP and cumulative exposure history and sociodemographic factors individually. Matched, adjusted ORs were obtained by conditional logistic regression to estimate the effect of any one variable while controlling for the effect of all the others.

Results:Results of the unadjusted analysis, considering variables one at a time, yielded no significant associations between NMRDxIP and any of the exposure or sociodemographic variables. The smoking OR was substantially increased (OR 5.09; 95%CI 0.65 to undeterimed). Also, there were no significant variables in a conditional logistic regression analysis in which all variables were simultaneously adjusted. ORs for respirable glass fibres were below unity at all concentrations of exposure in the adjusted analysis. For respirable silica there was no consistent relation across all exposure levels. The ORs increased through the first three exposure concentrations but decreased for the highest exposure. However, ORs although not significant, are greater than unity for all respirable concentrations of silica exposure.

Conclusions:The findings for Kansas City show no association between respirable glass fibres and NMRDxIP. The adjusted ORs for all exposures to respirable fibres were less than unity. On the other hand, the ORs for silica exposures were all above unity although there was no clear dose-response relation and none of the ORs were significant. Exposures for all substances considered were very low. Further, given the number of cases and controls, the statistical power to detect relatively small increases in risk, if any increase truly exited, was relatively low. The ORs for exposures to silica were all above unity although there was no clear dose-response relation and none of the ORs were significant. These raised ORs for silica suggest that continued surveillance would be prudent.
Respiratory morbidity in a population of French dental technicians
Authors: Radi S , Dalphin J C , Manzoni P , Pernet D , Leboube M P , Viel J F
Published: July 2002

Aims:To compare wage earner dental technicians with non-exposed salaried subjects for the prevalence of respiratory symptoms and function, and chestxray abnormalities.

Methods:A total of 134 dental technicians and 131 non-exposed subjects participated. A medical and an occupational questionnaire were filled in to evaluate the prevalence of respiratory symptoms and occupational exposures. Subjects underwent respiratory tests and chestxray examination.

Results:Mean age of the dental technicians was 36.6 years with a mean duration of dental work of 16.5 years. There was a significant risk of cough (day and night) and usual phlegm in dental technicians. Respiratory function parameters were lower in dental technicians with a significant difference between exposed and non-exposed groups for % FVC (forced vital capacity), % FEF25(forced mid expiratory flow), and % FEF50. The prevalence of small opacities increased with age. Small opacities were significantly related to an exposure to asbestos in the past.

Conclusions:Our young population of dental technicians is at risk of respiratory morbidity. They should benefit from adequate technical prevention measures.
Helicobacter pylori
Authors: Bateson Malcolm C
Published: July 2002

Helicobacter pyloriinfection is a major cause of peptic ulcer disease, and its detection and eradication are now an important part of gastroenterology. Effective regimes are available which will eliminate the organism in about 90% of cases in developed countries.
The real cost of aspirin
Authors: Burgess M I , Densem C G , Brooks N H , Levy R D , Lee H S
Published: July 2002

Aspirin is a widely used drug and perceived by most physicians to be inexpensive. High rates of concurrent gastroprotective agents are reported from a study of cardiology outpatients. Aspirin takers are more likely to also be taking a proton pump inhibitor, H2 antagonist, or antacid than non-aspirin takers. They are more than 10 times as likely to be experiencing upper gastrointestinal symptoms. Although aspirin is inexpensive, it is emphasised that the overall cost implications for therapy can be significant and it is suggested that it may be more appropriate to consider the use of alternative antiplatelet agents in patients who tolerate aspirin poorly.
Autoamputation of the tongue
Authors: Patel A K , Chaturvedi P , Panday R K , Sanyal B
Published: July 2002

Autoamputation is an uncommon phenomenon that has been reported for the fingers, toes, appendix, ovary, spleen, etc. Autoamputation of the tongue has never been reported. An elderly man with carcinoma of lateral pharyngeal wall and tonsil presented with an autoamputated tongue that was attached to the oral cavity with a thin band. The patient required detachment of the tongue and tracheostomy followed by radiotherapy for the primary tumour.
Prognostic value of stress echocardiography in women with high (⩾80%) probability of coronary artery disease
Authors: Davar J I , Roberts E B , Coghlan J G , Evans T R , Lipkin D P
Published: July 2002

OBJECTIVE

To assess the prognostic significance of stress echocardiography in women with a high probability of coronary artery disease (CAD).

SETTING

Secondary and tertiary cardiology unit at a university teaching hospital.

PARTICIPANTS

A total of 135 women (mean (SD) age 63 (9) years) with pre-test probability of CAD ⩾80% were selected from a database of patients investigated by treadmill or dobutamine stress echocardiography between 1995 and 1998.

MAIN OUTCOME MEASURES

Patients were followed up for occurrence of subsequent cardiac events (cardiac death, myocardial infarction, admission with unstable angina, and revascularisation) using a structured telephone interview and case note review.

RESULTS

Each patient had between two and seven (mean 3.5) CAD risk factors and pre-test probability of CAD ⩾80%. Ninety three patients (68.9%) had negative stress echocardiography. Mean (SD) follow up was 20.1 (8.5) months. There were six events in the positive stress echocardiography group (two cardiac deaths, one unstable angina, three revascularisations), and one event in the negative stress echocardiography group. Cox regression analysis showed positive stress echocardiography (p=0.02) and age (p=0.03) to be the only univariate predictors and positive stress echocardiography to be the only independent predictor of future cardiac events (relative risk 8.9, confidence interval 1.0 to 76.5, p=0.04). Cumulative event free survival to 38 months was 98% in the negative stress echocardiography and 50.7% in the positive stress echocardiography groups.

CONCLUSION

In women with high pre-test likelihood of CAD: (1) negative stress echocardiography identifies a subgroup with low risk of cardiac events who do not require further invasive investigation and (2) positive stress echocardiography identifies a subgroup with increased risk of subsequent cardiac events.
A rare presentation of a common disease
Authors: Patel H , Hindle K S , Tsavellas G , Huang A
Published: July 2002

A previously well 77 year old man presented with acute left iliac fossa pain. He was pyrexial and tachycardic with localised abdominal guarding but there was no palpable mass or generalised peritonitis. Respiratory examination revealed tachypnoea with normal bilateral air entry and no tracheal deviation. Blood investigations showed a leucocytosis with raised serum C reactive protein and erythrocyte sedimentation rate. Serum amylase was normal and he was hypoxic with reduced oxygen saturation in the blood. His abdominal and erect thoracic radiographs are shown (figs 1 and 2). He also underwent abdominal computed tomography (fig 3).
Dysphagia in a patient with palmoplantar keratoderma
Authors: Morgan R
Published: July 2002

A 72 year old man was referred by his general practitioner with a four month history of dysphagia. Physical examination wasunremarkable with the exception of his hands and feet which showed hyperkeratosis on the palms (fig 1) and soles of his feet. Gastroscopy showed severe extensive oesophagitis (grade III) confirmed with multiple oesophageal biopsies. He was started on a proton pump inhibitor (omeprazole) and rescoped three months later. He still had oesophagitis at this time, although macroscopically it had improved; repeat biopsies again showed oesophagitis. A further gastroscopy three months later showed complete resolution of his oesophagitis confirmed by repeated oesophageal biopsies. He remains well and asymptomatic on omeprazole and continues to be followed up.
Painful chest wall swelling
Authors: Shah D V , Ladhani S , Joshi J M
Published: July 2002

A 70 year old man, a non-smoker, presented with a painful swelling over the right sternoclavicular joint and low grade continuous fever for a period of two months. The patient had been empirically started on antituberculous therapy on the suspicion of tuberculous osteomyelitis, but his fever and swelling persisted.
Acute myeloid leukaemia with tell-tale computed tomography scans
Authors: Fadilah S A W , Cheong S K , Maimunah A , Toh S T , Shamin A S
Published: July 2002

A 36 year old man with acute myeloid leukaemia presented with recurrent episodes of fever and a three day history of right sided pleuritic pain and left upper abdominal pain after two cycles of chemotherapy. The patient had received several broad spectrum antibiotics with no clinical improvement. On examination, his temperature was 40.2°C and there was no evidence of Hickman catheter infection both in terms of local evidence and catheter blood cultures. Coarse crackles were noted over the base of the right lung. The liver, spleen, and peripheral lymph nodes were not enlarged. Bone marrow examination showed hypocellular marrow with no excess of blast cells. The neutrophil count was less than 0.05 × 109/l for three weeks. Cultures of the blood were repeatedly negative. Chest radiography after two courses of chemotherapy was normal. Computed tomograms of the thorax and abdomen are shown in figs 1 and 2.
Risk Matters in Healthcare
Authors: Stewart J A D
Published: July 2002

It would be disingenuous of me to claim that I was looking forward to reviewing this book. However I am glad to say I was pleasantly surprised. Although it is obviously directed at the primary healthcare sector, this slim volume contains such valuable insights into the nature of risk and risk management as to be of interest to the hospital doctor. Indeed part 1 of the book, which first defines risk in an everyday context and then discusses the difficulty of communicating risk to the individual, is so clearly written that it should be essential reading for all healthcare professionals who directly manage patients. As a direct consequence of following such a tour de force, part 2 (which discusses the specifics of risk management in primary care) seems a little disappointing. However, that is somewhat unkind, as it clearly identifies the main areas of risk in general practice (to doctors, patients, and staff) and gives sound guidance on risk management strategies. The book finishes with a personal development plan and “risk ready reckoner”.
Surveillance in Barrett’s oesophagus: a personal view
Authors: Basu K K , de Caestecker J S
Published: July 2002

Barrett’s oesophagus is defined as columnar-lined oesophagus of any length containing specialised intestinal metaplasia. Diagnosis depends on close corroboration between the endoscopist and histopathologist. It occurs in 10% of patients presenting endoscopically with reflux symptoms and has an adenocarcinoma incidence of 0.4% to 2%. Surveillance is performed to detect precancerous change (dysplasia) and early stage disease has a good surgical prognosis. Computer models suggest cost efficacy comparable to other health measures. However most patients with Barrett’s do not die of oesophageal cancer and elective oesophagectomy has an appreciable mortality. Endoscopic ablation techniques and improved definition of high risk subgroups will help shape future surveillance programmes.
Postgraduate training in family medicine in Albania
Authors: Rrumbullaku L , Theodorakis P N , Pulluqi P , Lionis C , Trell E
Published: July 2002

In the Balkan context education in general practice varies greatly and it is in different stages of reorganisation and curriculum development. The postgraduate training in family medicine in Albania started in January 1997 with the goal of providing future family doctors with the proper knowledge, skills, attitudes, and professional values that will enable them to address the medical problems in the community. This paper describes the structure and content of the training programme and discusses some of its key elements.
An aggressive policy of bilateral saphenous vein harvest for infragenicular revascularisation in the era of multidrug resistant bacteria
Authors: Murphy G J , Kipgen D , Dennis M J S , Sayers R D
Published: July 2002

Background

The success of infragenicular revascularisation for lower limb ischaemia is limited by the high proportion of patients without ipsilateral long saphenous vein (LSV) of adequate length or quality. The aim of this study was to report the results of an autogenous vein only policy for infragenicular revascularisation utilising contralateral LSV when ipsilateral LSV is inadequate. The treatment and outcome of infection of autogenous grafts with methicillin resistant Staphylococcus aureus (MRSA) is also reported.

Patients and methods

The vascular audit database and patient case notes were reviewed retrospectively for patients with arterial occlusive disease requiring infragenicular reconstruction. There were 68 critically ischaemic legs in 65 patients of whom 48 were male: median age (range) 74 years (41–94), over a three year period.

Results

Thirty six patients (53%) underwent revascularisation (eight infragenicular femoropopliteal bypass, 28 femorodistal), 24 (35%) underwent primary amputation and a further eight (12%) were found to have unsuitable distal vessels for revascularisation after tibial vessel exploration and intraoperative angiography. Thirty three grafts (92%) utilised LSV and three (8%) were polytetrafluoroethylene grafts. Thirteen patients (39%) lacked adequate ipsilateral LSV of whom 12 had the contralateral leg explored providing suitable LSV in 10/12 (83%). Contralateral LSV was used as a single length conduit in two cases and as a venovenous composite graft in eight cases. Primary, primary assisted, and secondary patency rates at two years were 38%, 77%, and 81% respectively. Actuarial limb survival and patient survival rates at two years were 86% and 61% respectively. Eleven patients developed ipsilateral wound complications (30%) including seven (21%) who developed MRSA infection of the ipsilateral leg wound. MRSA wound infection was treated successfully in all cases by antibiotic therapy (intravenous vancomycin). No patient subsequently required saphenous vein harvesting for a secondary reconstruction or coronary artery bypass graft.

Conclusion

Excellent long term results can be achieved using autogenous vein for infragenicular revascularisation and the contralateral LSV is an excellent alternative in the absence of suitable ipsilateral LSV. Autogenous vein may confer some protection against severe complications observed with MRSA infection seen in vascular patients and therefore its use is recommended.
Sediment transfer by shallow landsliding in the Queen Charlotte Islands, British Columbia
Authors: Martin Yvonne , Rood Kenneth , Schwab James W , Church Michael
Published: July 2002

Despite the importance of landsliding in routing sediment through mountainous drainage basins, few studies have documented landsliding rates over extended time and space scales. We have investigated landsliding in surficial material in the Queen Charlotte Islands using a large inventory of events, derived from aerial photography, covering an area of 166.7 km2. The mean erosion rate for shallow landsliding is 0.10 mm·a1, which is at the upper end of shallow landsliding rates observed in the Pacific Northwest and coastal British Columbia, but several orders of magnitude lower than rock-based landsliding rates reported in the literature. Probability distributions for landslide area and volume are somewhat convex in form. Flattening of the curve found at low magnitudes may be due to sampling bias or physical mechanisms inhibiting failure, and the steepening for high values may exist because the sampling period is not long enough to adequately represent large events. Landslides generally initiate on hillslope gradients greater than 0.500.60. The largest numbers of landslides occur on south- to southwest-facing slopes and east- to northeast-facing slopes. Most events occur on concave and straight hillslopes in upper-slope positions. Landsliding rates were found not to be affected by rock type. Hillslopes in the Queen Charlotte Islands are often mantled by weathered Quaternary deposits and, hence, landsliding events are not directly controlled by weathering of bedrock. About 31% of landslides identified in this study deposited material in stream reaches, with about 83% of these landslides deposited in reaches with gradients between 3% and 10%.
Fazlur Khan (19291982): reflections on his life and works
Authors: Mufti Aftab A , Bakht Baidar
Published: July 2002

Tall buildings, or skyscrapers, are icons of cities, symbols of corporate power, and a mark of national pride. Certain skyscrapers, such as the John Hancock Center and the Sears Tower in Chicago, are also marvels of engineering that have paved the way for ever increasing heights of structural systems. Since the 1960s, a series of new structural systems has been introduced with the objective of achieving economically-competitive and aesthetically-pleasing tall buildings without compromising safety. One of the great structural engineers responsible for the new structural systems was Dr. Fazlur Rahman Khan. This paper provides a biographical sketch of Dr. Khan and discusses some of his innovations pertaining to high-rise buildings. It shows that his contributions led to a new vertical scale for the modern day city.Key words: aesthetics, architecture, innovation, structural system, tall building.
Calmodulin-dependent cyclic nucleotide phosphodiesterase in an experimental rat model of cardiac ischemiareperfusion
Authors: Kakkar Rakesh , Seitz Dallas P , Kanthan Rani , Rajala Raju VS , Radhi Jasim M , Wang Xinto , Pasha Mohammed K , Wang Rui , Sharma Rajendra K
Published: July 2002

In the present study, we investigated the activity and expression of calmodulin-dependent cyclic nucleotide phosphodiesterase (CaMPDE) and the effects of calpains in rat heart after ischemia and reperfusion. Immunohistochemical studies indicated that CaMPDE in normal heart is localized in myocardial cells. Rat ischemic heart showed a decrease in CaMPDE activity in the presence of Ca2+and calmodulin; however, in ischemicreperfusion tissue a progressive increase in Ca2+and calmodulin-independent cyclic nucleotide phosphodiesterase (CaM-independent PDE) activity was observed. Perfusion of hearts with cell-permeable calpain inhibitor suppressed the increase of Ca2+and CaM-independent PDE activity. Protein expression of CaMPDE was uneffected by hypoxic injury to rat myocardium. The purified heart CaMPDE was proteolyzed by calpains into a 45 kDa immunoreactive fragment in vitro. Based on these results, we propose that hypoxic injury to rat myocardium results in the generation of CaM-independent PDE by calpain mediated proteolysis, allowing the maintenance of cAMP concentrations within the physiological range.Key words: phosphodiesterase, calmodulin, calpains, heart, ischemia, reperfusion.
Relating the unique sensory system of amblypygids to the ecology and behavior ofPhrynus parvulusfrom Costa Rica (Arachnida, Amblypygi)
Authors: Hebets Eileen A
Published: July 2002

While the unique sensory system and neuroanatomy of amblypygids suggest that olfaction is important in their lives, to date no behavioral data exist to support this suggestion. To gain insight into amblypygid ecology and behavior, an individual markrecapture study was conducted on the Costa Rican amblypygid Phrynus parvulus. Within two 50 by 25 m plots, the distribution and movement patterns of individual amblypygids were recorded for over 2 months. A total of 88 adult individuals (60 males and 28 females) were marked, with an average 51% resighted. Females were resighted more frequently than males (75% females, 40% males). The sexes did not differ in their frequency or movement distance, but females were more likely to be seen on the same tree over time. While both sexes potentially wander in search of mates, females may also be searching for a good crevice, or diurnal hideout. Once a female has mated and laid eggs, she likely remains stationary. Movement patterns and tree choice seem to be dictated by both the presence of conspecifics and environmental factors such as tree surface area, moss cover, and the presence of buttressing. Cumulative observational data collected over 3 years suggest that the main breeding season for this species is October-January. Both mate attraction and navigation may be facilitated by the olfactory capabilities of amblypygids, while their giant interneurons may be involved in their foraging behavior.
HOLES AND DOMINOES IN MEYNIEL GRAPHS
Authors: ROUSSEL FLORIAN , RUSU IRENA
Published: July 2002

Many practical problems (frequency assignement, register allocation, timetables) may be formulated as graph (vertex-)coloring problems, but finding solutions for them is difficult as long as they are treated in the most general case (where the graph is arbitrary), since vertex coloring has been proved to be NP-complete. The problem becomes much easier to solve if the graph resulting from the modelisation of the practical application belongs to some particular class of graphs, for which solutions to the problem are known. Meyniel graphs form such a class (a fast coloring algorithm can be found in [9]), for which an efficient recognizing algorithm is therefore needed.

A graph G=(V,E) is said to be a Meyniel graph if every odd cycle of G on at least five vertices contains at least two chords. Meyniel graphs generalize both i-triangulated and parity graphs, two well known classes of perfect graphs that will be present in our paper in Section 7.

In [2], Burlet and Fonlupt propose a characterization of Meyniel graphs which relies on the following property: the class of Meyniel graphs may be obtained from some basic Meyniel graphs using a binary operation called amalgam. Besides the theoretical interest of this result, a practical interest arises because of the polynomial recognition algorithm which can be obtained. Unfortunately, it is quite expensive to verify if a given graph is the amalgam of two graphs (therefore the complexity of the whole algorithm is in O(n7)), and this supports the idea that a new point of view is needed to find a more efficient algorithm.

Our approach of Meyniel graphs will be directed through the search of a general structure. Intuitively, a Meyniel graph either will be simple (i.e. with no hole or domino), or will have a skeleton around which the rest of the graph will be regularly organized. As suggested, the first type of Meyniel graphs is simple to identify. For the second type, a deeper analysis is necessary; it yields a characterization theorem, which is used to deduce the O(m2+mn) recognition algorithm.
FORMAL AND ANALYTIC DEFORMATIONS FROM WITT TO VIRASORO
Authors: GUERRINI L.
Published: July 2002

We introduce a new family [Formula: see text] of deformations of the Witt algebra [Formula: see text], F varying in the space of all polynomials with vanishing constant terms, and show the existence of an isomorphism of its formal and analytic completions with those of the Witt algebra. Central extensions of this algebra are considered and the existence of an isomorphism between their formal and analytic completions with those of the Virasoro algebra is proved.
QUANTIZATION AND SUPERSELECTION SECTORS I: TRANSFORMATION GROUP C*-ALGEBRAS
Authors: LANDSMAN N.P.
Published: July 2002

Quantization is defined as the act of assigning an appropriate C*-algebra [Formula: see text] to a given configuration space Q, along with a prescription mapping self-adjoint elements of [Formula: see text] into physically interpretable observables. This procedure is adopted to solve the problem of quantizing a particle moving on a homogeneous locally compact configuration space Q=G/H. Here [Formula: see text] is chosen to be the transformation group C*-algebra corresponding to the canonical action of G on Q. The structure of these algebras and their representations are examined in some detail. Inequivalent quantizations are identified with inequivalent irreducible representations of the C*-algebra corresponding to the system, hence with its superselection sectors.

Introducing the concept of a pre-Hamiltonian, we construct a large class of G-invariant time-evolutions on these algebras, and find the Hamiltonians implementing these time-evolutions in each irreducible representation of [Formula: see text]. “Topological” terms in the Hamiltonian (or the corresponding action) turn out to be representation-dependent, and are automatically induced by the quantization procedure. Known “topological” charge quantization or periodicity conditions are then identically satisfied as a consequence of the representation theory of [Formula: see text].
NOISE AND DISSIPATION IN QUANTUM THEORY
Authors: ACCARDI LUIGI
Published: July 2002

A model independent generalization of quantum mechanics, including the usual as well as the dissipative quantum systems, is proposed. The theory is developed deductively from the basic principles of the standard quantum theory, the only new qualitative assumption being that we allow the wave operator at time t of a quantum system to be non-differentiable (in t) in the usual sense, but only in an appropriately defined (Sec. 5) stochastic sense. The resulting theory is shown to lead to a natural generalization of the usual quantum equations of motion, both in the form of the Schrödinger equation in interaction representation (Sec. 6) and of the Heisenberg equation (Sec. 8). The former equation leads in particular to a quantum fluctuation-dissipation relation of Einstein’s type. The latter equation is a generalized Langevin equation, from which the known form of the generalized master equation can be deduced via the quantum Feynmann-Kac technique (Secs. 9 and 10). For quantum noises with increments commuting with the past the quantum Langevin equation defines a closed system of (usually nonlinear) stochastic differential equations for the observables defining the coefficients of the noises. Such systems are parametrized by certain Lie algebras of observables of the system (Sec. 10). With appropriate choices of these Lie algebras one can deduce generalizations and corrections of several phenomenological equations previously introduced at different times to explain different phenomena. Two examples are considered: the Lie algebra [q, p]=i (Sec. 12), which is shown to lead to the equations of the damped harmonic oscillator; and the Lie algebra of SO(3) (Sec. 13) which is shown to lead to the Bloch equations. In both cases the equations obtained are independent of the model of noise. Moreover, in the former case, it is proved that the only possible noises which preserve the commutation relations of p, q are the quantum Brownian motions, commonly used in laser theory and solid state physics.
ON THE INDEPENDENCE OF LOCAL ALGEBRAS IN QUANTUM FIELD THEORY
Authors: SUMMERS STEPHEN J.
Published: July 2002

A review is made of the multitude of different mathematical formalizations of the physical concept ‘two observables (or two systems) are independent’ that have been proposed in quantum theories, particularly relativistic quantum field theory. The most basic mathematical formulation of independence in any quantum theory is what one may call kinematical independence: the two observables, resp. the observables of the two quantum systems, which are represented by elements of a C*-algebra, resp. two subalgebras of a C*-algebra, are required to commute. This is related to a mathematical formulation of the notion of the coexistence (or compatibility) of two observables. Another basic notion of independence, generally called statistical independence in the literature, is, roughly speaking, two quantum systems are said to be statistically independent if each can be prepared in any state, how ever the other system has been prepared. There are numerous mathematical formulations of this notion and their interrelationships are explained. Statistical independence and kinematical independence are shown to be logically independent. Additional notions such as strict locality and their relation to statistical independence are discussed. The mathematics of a more quantitative measure of statistical independence, Bell’s inequalities, is reviewed and its relations with previously introduced notions are indicated. All of these notions are then viewed in application to relativistic quantum field theory.
REGULARITY OF SOLUTIONS FOR SINGULAR SCHRÖDINGER EQUATIONS
Authors: HINZ ANDREAS M.
Published: July 2002

Local and global regularity properties of weak solutions of the Schrödinger equation −Δu+qu=λu play an important role in the spectral theory of the corresponding operator [Formula: see text]. Central among these properties is local boundedness of the solutions u, which is derived in an elementary way for potentials q whose negative parts q− lie in the local Kato class K loc . The method also provides mean value inequalities for and, in case q+ is in K loc too, continuity of u.

To employ these mean value inequalities for bounds on eigenfunctions of T in a fixed direction, classes Kρ are introduced which reflect the behavior of q at infinity. A couple of examples allow to compare these classes with more conservative ones like the Stummel class Q and the global Kato class K.

The fundamental property of local boundedness of solutions also serves as a base for a very short proof of the self-adjointness of T if the operator is bounded from below and q−∈K loc . If q(x) is permitted to go to −∞, as |x|→∞, a large class K ρ which guarantees self-adjointness of T is derived and contains the case q−(x)= O (|x|2).

The Spectral Theorem then allows to deduce rapidly decaying bounds on eigenfunctions for discrete eigenvalues, at least if q−(x)= o (|x|2). This is also the condition under which the existence of a bounded solution is sufficient to guarantee λ∈σ(T). Here q−(x)= O (|x|2) appears as a borderline case and is discussed at some length by means of an explicit example.

The class of admissible operators extending to these borderline cases with potentials singular locally and at infinity, the regularity results for solutions being mostly optimal, as demonstrated by numerous examples, yet the proofs being shorter and more straightforward than those to be found in literature for smaller classes and weaker results, the sets Kρ under consideration and the methods employed appear to be quite natural.
CLUSTER PROPERTIES OF ONE PARTICLE SCHRÖDINGER OPERATORS
Authors: KOSTRYKIN V. , SCHRADER R.
Published: July 2002

Cluster properties of one particle Schrödinger operators are proved, where the potential is the sum of two terms and the center of one is moved to infinity. These cluster properties hold for the on-shell S-matrix elements, the spectral shift functions (and thus the total phase shift) as well as their Laplace transforms, i.e. the traces of the differences of appropriate heat kernels.
ON MARTINEZ’ METHOD OF PHASE SPACE TUNNELING
Authors: NAKAMURA SHU
Published: July 2002

A generalization of the method of martinez on phase space tunneling is discussed. In particular, the key estimate is formulated for a class of ħ-pseudodifferential operators.
QUANTUM SUPERGROUPS AND TOPOLOGICAL INVARIANTS OF THREE-MANIFOLDS
Authors: ZHANG R.B.
Published: July 2002

The Reshetikhin-Turaev approach to topological invariants of three-manifolds is generalized to quantum supergroups. A general method for constructing three-manifold invariant is developed, which requires only the study of the eigenvalues of certain central elements of the quantum supergroup in irreducible representations. To illustrate how the method works, Uq(gl(2|1)) at odd roots of unity is studied in detail, and the corresponding topological invariants are obtained.
HIGHER ORDER TRACE RELATIONS FOR SCHRÖDINGER OPERATORS
Authors: GESZTESY F. , HOLDEN H. , SIMON B. , ZHAO Z.
Published: July 2002

We extend the trace formula recently proven for general one-dimensional Schrödinger operators which obtains the potential V(x) from a function ξ(x, λ) by deriving trace relations computing moments of ξ(λ, x) dλ in terms of polynomials in the derivatives of V at x. We describe the relation of those polynomials to KdV invariants. We also discuss trace formulae for analogs of ξ associated with boundary conditions other than the Dirichlet boundary condition underlying ξ.
FUNCTIONALS OF CLASSICAL FIELDS IN QUANTUM FIELD THEORY
Authors: SCHMITT T.
Published: July 2002

Many methods of modern quantum field theory rely heavily on functionals of classical fields; this notion is however problematic whenever anticommuting fields are present. We propose a calculus for such functionals which avoids the use of auxiliary Grassmann algebras, and which relies on an infinite-dimensional version of Berezin-Leites supermanifold theory. We begin by studying “functional power series expansions” without growth conditions; this already allows to make e.g. the Yang-Mills action functional with fermionic, anticommuting matter fields a well-defined mathematical object.

We introduce analytical conditions on power series which enable us to substitute them into each other, and we globalize them to superfunctionals. Also, infinitesimal transformation laws of the fields are discussed.
ON THE ALGEBRAIC THEORY OF SOLITON AND ANTISOLITON SECTORS
Authors: SCHLINGEMANN DIRK
Published: July 2002

We consider the properties of massive one-particle states on a translation covariant Haag-Kastler net in Minkowski space. In two-dimensional theories, these states can be interpreted as soliton states and we are interested in the existence of antisolitons. It is shown that for each soliton state there are three different possibilities for the construction of an antisoliton sector which are equivalent if the (statistical) dimension of the corresponding soliton sector is finite.
A Scaling Limit of a Hamiltonian of Many Nonrelativistic Particles Interacting with a Quantized Radiation Field
Authors: Hiroshima Fumio
Published: July 2002

This paper presents a scaling limit of Hamiltonians which describe interactions of N-nonrelativistic charged particles in a scalar potential and a quantized radiation field in the Coulomb gauge with the dipole approximation. The scaling limit defines effective potentials. In one-nonrelativistic particle case, the effective potentials have been known to be Gaussian transformations of the scalar potential [J. Math. Phys.34 (1993) 4478–4518]. However it is shown that the effective potentials in the case of N-nonrelativistic particles are not necessary to be Gaussian transformations of the scalar potential.
Symmetry Groups in Quantum Mechanics and the Theorem of Wigner on the Symmetry Transformations
Authors: Cassinelli Gianni , de Vito Ernesto , Lahti Pekka J. , Levrero Alberto
Published: July 2002

Various mathematical formulations of the symmetry group in quantum mechanics are investigated and shown to be mutually equivalent. A new proof of the theorem of Wigner on the symmetry transformations is worked out.
THE DEFINITION OF NEVEU–SCHWARZ SUPERCONFORMAL FIELDS AND UNCHARGED SUPERCONFORMAL TRANSFORMATIONS
Authors: DÖRRZAPF MATTHIAS
Published: July 2002

The construction of Neveu–Schwarz superconformal field theories for any N is given via a superfield formalism. We also review some results and definitions of superconformal manifolds and generalise contour integration and Taylor expansion to superconformal spaces. For arbitrary N we define (uncharged) primary fields and give their infinitesimal change under superconformal transformations. This leads us to the operator product expansion of the stress-energy tensor with itself and with primary fields. In this way we derive the well-known commutation relations of the Neveu–Schwarz superconformal algebras K N . In this context we observe that the central extension term disappears for N≥4 for the Neveu–Schwarz theories. Finally, we give the global transformation rules of primary fields under theaction of the algebra generators.
THE EUCLIDEAN TRAVELLING SALESMAN PROBLEM: FREQUENCY DISTRIBUTION OF NEIGHBORS FOR SMALL-SIZE SYSTEMS
Authors: CHAKRABORTI ANIRBAN
Published: July 2002

We have studied numerically the frequency distribution ρ(n) of the nth neighbour along the optimal tour in the Euclidean travelling salesman problem for N cities, in dimensions d = 2 and d = 3. We find there is no significant dependence of ρ(n) on either the number of cities N or the dimension d.
SIMPLE PATTERNS IN FLUCTUATIONS OF TIME SERIES OF ECONOMIC INTEREST
Authors: FANCHIOTTI H. , GARCÍA CANAL C. A. , GARCÍA ZÚÑIGA H.
Published: July 2002

Time series corresponding to nominal exchange rates between the US dollar and Argentina, Brazil and European Economic Community currencies; different financial indexes as the Industrial Dow Jones, the British Footsie, the German DAX Composite, the Australian Share Price and the Nikkei Cash and also different Argentine local tax revenues, are analyzed looking for the appearance of simple patterns and the possible definition of forecast evaluators. In every case, the statistical fractal dimensions are obtained from the behavior of the corresponding variance of increments at a given lag. The detrended fluctuation analysis of the data in terms of the corresponding exponent in the resulting power law is carried out. Finally, the frequency power spectra of all the time series considered are computed and compared
BORNHOLDT'S SPIN MODEL OF A MARKET DYNAMICS IN HIGH DIMENSIONS
Authors: YAMANO TAKUYA
Published: July 2002

We present results of an extension of the market model introduced by Bornholdt to high dimensions. Three and four dimensions are shown to behave similar to two, for suitable parameters.
AN EPIDEMIC MODEL ON SMALL-WORLD NETWORKS AND RING VACCINATION
Authors: AHMED E. , HEGAZI A. S. , ELGAZZAR A. S.
Published: July 2002

A modified version of susceptible-infected-recovered-susceptible (SIRS) model for the outbreaks of foot-and-mouth disease (FMD) is introduced. The model is defined on small-world networks, and a ring vaccination programme is included. This model can be a theoretical explanation for the nonlocal interactions in epidemic spreading. Ring vaccination is capable of eradicating FMD provided that the probability of infection is high enough. Also an analytical approximation for this model is studied.
A PERCOLATION MODEL OF DIAGENESIS
Authors: MANNA S. S. , DATTA T. , KARMAKAR R. , TARAFDAR S.
Published: July 2002

The restructuring process of diagenesis in the sedimentary rocks is studied using a percolation type model. The cementation and dissolution processes are modeled by the culling of occupied sites in rarefied and growth of vacant sites in dense environments. Starting from sub-critical states of ordinary percolation the system evolves under the diagenetic rules to critical percolation configurations. Our numerical simulation results in two dimensions indicate that the stable configuration has the same critical behavior as the ordinary percolation.
SMALL x DIVERGENCES IN THE SIMILARITY RG APPROACH TO LF QCD
Authors: BRISUDOVA MARTINA
Published: July 2002

We study small x divergences in boost invariant similarity renormalization group approach to light-front QCD in a heavy quark–antiquark state. With the boost invariance maintained, the infrared divergences do not cancel out in the physical states, contrary to previous studies where boost invariance was violated by a choice of a renormalization scale. This may be an indication that the zero mode, or nontrivial light-cone vacuum structure, might be important for recovering full Lorentz invariance.
INFLATION, QUINTESSENCE PROBLEM AND VARYING SPEED OF LIGHT
Authors: CHAKRABORTY SUBENOY
Published: July 2002

In this paper it is shown that the present accelerated expansion of the Universe can be explained only by considering variation of the speed of light, without taking into account the cosmological constant or quintessence matter.
RENORMALIZATION GROUP ANALYSIS OF A TWO-DIMENSIONAL INTERACTING ELECTRON SYSTEM
Authors: METZNER WALTER
Published: July 2002

We describe a Wick ordered functional renormalization group method for interacting Fermi systems, where the complete flow from the bare action of the microscopic model to the effective low-energy action is obtained from a differential flow equation. We apply this renormalization group approach to a prototypical two-dimensional lattice electron system, the Hubbard model on a square lattice. The flow equation for the effective interactions is evaluated numerically on 1-loop level. The effective interactions diverge at a finite energy scale which is exponentially small for small bare interactions. To analyze the nature of the instabilities signalled by the diverging interactions we compute the flow of the singlet superconducting susceptibilities for various pairing symmetries and also charge and spin density susceptibilities. Depending on the choice of the model parameters (hopping amplitudes, interaction strength and band-filling) we find antiferromagnetic order or d-wave superconductivity as leading symmetry breaking instability.
THE EXACT RENORMALIZATION GROUP AND FIRST-ORDER PHASE TRANSITIONS
Authors: TETRADIS N.
Published: July 2002

Studies of first-order phase transitions through the use of the exact renormalization group are reviewed. In the first part the emphasis is on universal aspects: We discuss the universal critical behaviour near weakly first-order phase transitions for a three-dimensional model of two coupled scalar fields – the cubic anisotropy model. In the second part we review the application of the exact renormalization group to the calculation of bubble-nucleation rates. More specifically, we concentrate on the pre-exponential factor. We discuss the reliability of homogeneous nucleation theory that employs a saddle-point expansion around the critical bubble for the calculation of the nucleation rate.