bluuebunny/crossref_metadata_2025 huggingface dataset:
The clinical impact of metabolic bone disease in coeliac disease
Authors: Fickling W E , McFarlane X A , Bhalla A K , Robertson D A F
Published: July 2002

Bone mineral density was measured by dual energy x ray absorptiometry (DEXA) at the lumbar spine and femoral neck in 15 adults who had metabolic bone disease in association with coeliac disease (mean age at diagnosis 53.5 years, range 37 to 66). Results were expressed as a T score (the number of standard deviations by which patient’s bone density differed from the sex matched young adult mean). Three patients had no skeletal symptoms and normal routine calcium biochemistry but severely reduced axial bone mineral density on DEXA. Eleven patients had symptomatic skeletal fractures, including fractures of proximal femur (3), vertebrae (4), and radius (6). Three patients had osteomalacia confirmed on bone biopsy, two of whom had characteristic biochemistry. Secondary and tertiary hyperparathyroidism were seen. Seventy five further patients (60 female) with coeliac disease (mean age 52.0 years, median duration of gluten-free diet 3.4 years) and 75 paired healthy age and sex matched controls were questioned on past fracture history. Patients with coeliac disease underwent detailed studies of calcium biochemistry, dietary intake, and bone mineral density. Sixteen had a past history of fractures (χ2 = 10.7, p = 0.0004,v controls), which were of typical osteoporotic type. Ten patients had fracture before diagnosis of coeliac disease and six after diagnosis. Patients who had a fracture were older (56.3 v 50.3 years, p < 0.02, Wilcoxon rank sum test) than those with no fracture. There was no significant difference in bone mineral density (z score −0.31v −0.77), serum calcium (2.30v 2.26 mmol/l), 25-hydroxyvitamin D (19.7v 23.7 nmol/l), parathyroid hormone (2.6v 3.1 pmol/l), or dietary calcium intake (1021.0 v 1033.0 mg/day) in patients with fracture compared with those without fracture. Metabolic bone disease is common in coeliac disease and is associated with premature osteoporotic fractures.
Gas gangrene after colonoscopy
Authors: Jamieson N F , Willoughby C P
Published: July 2002

A case of spontaneous clostridial myonecrosis developing shortly after diagnostic colonoscopy is described. The prime underlying factor proved to be an unsuspected colonic cancer, developing in a patient with pre-existing ulcerative colitis and sclerosing cholangitis.
Non-hepatic hyperammonaemia: an important, potentially reversible cause of encephalopathy
Authors: Hawkes N D , Thomas G A O , Jurewicz A , Williams O M , Hillier C E M , McQueen I N F , Shortland G
Published: July 2002

The clinical syndrome of encephalopathy is most often encountered in the context of decompensated liver disease and the diagnosis is usually clear cut. Non-hepatic causes of encephalopathy are rarer and tend to present to a wide range of medical specialties with variable and episodic symptoms. Delay can result in the development of potentially life threatening complications, such as seizures and coma.

Early recognition is vital. A history of similar episodes or clinical risk factors and early assessment of blood ammonia levels help establish the diagnosis. In addition to adequate supportive care, investigation of the underlying cause of the hyperammonaemia is essential and its reversal, where possible, will often result in complete recovery. Detection of an unborn error of metabolism should lead to the initiation of appropriate maintenance therapy and genetic counselling.
Actual and perceived impacts of tobacco regulation on restaurants and firms
Authors: Crémieux Pierre-Yves , Ouellette Pierre
Published: July 2002

OBJECTIVE

To examine the actual and anticipated costs of a law regulating workplace smoking and smoking in restaurants, taking into consideration observed and anticipated infrastructure costs, lost productivity, increased absenteeism, and loss of clientele.

SETTING AND DESIGN

A survey of 401 Québec restaurants and 600 Québec firms conducted by the Québec Ministry of Health before the enactment of the law was used to derive costs incurred by those who had already complied and anticipated by those that did not.

RESULTS

Direct and indirect costs associated with tobacco regulation at work and in restaurants were minimal. Annualised infrastructure costs amounted to less than 0.0002% of firm revenues and 0.15% of restaurant revenues. Anticipated costs were larger and amounted to 0.0004% of firm revenues and 0.41% of restaurant revenues. Impacts on productivity, absenteeism, and restaurant patronage were widely anticipated but not observed in currently compliant establishments.

CONCLUSION

Firms and restaurants expected high costs to result from strict tobacco regulation because of infrastructure costs, decreased productivity, and decreased patronage. That none of these were actually observed suggests that policy makers should discount industry claims that smoking regulations impose undue economic hardship.
Cigarette advertising and promotional strategies in retail outlets: results of a statewide survey in California
Authors: Feighery Ellen C , Ribisl Kurt M , Schleicher Nina , Lee Rebecca E , Halvorson Sonia
Published: July 2002

OBJECTIVE

To examine the extent and types of cigarette advertising materials in stores and to assess tobacco company compliance with the 1998 Master Settlement Agreement (MSA).

DESIGN

A cross-sectional analysis of a random sample of 586 stores that sold cigarettes.

SETTING

US state of California.

MAIN OUTCOME MEASURES

Trained data collectors classified cigarette advertising materials by type (signs, displays, functional items), location (interior or exterior), and placement (below 3 feet (1 m) or near candy).

RESULTS

California retail outlets featured 17.2 (SD 16.1) tobacco advertising materials on average, and 94% of stores featured at least some advertising. About 85% of these were within 4 feet (1.3 m) of the counter. About 50% of the stores had ads at or below 3 feet, and 23% had cigarette product displays next to candy. In violation of the MSA, 3% of stores featured signs with cartoons and 11% had large exterior signs.

CONCLUSIONS

Tobacco companies are aggressively using stores to market cigarettes. Moreover, the spirit of the MSA—to protect children from cigarette advertising—has not been realised. Future studies should monitor industry use of this venue and assess the impact of exposure to cigarette advertising materials in stores on adult smokers and youth.
Tobacco industry documents: comparing the Minnesota Depository and internet access
Authors: Balbach E D , Gasior R J , Barbeau E M
Published: July 2002

Objective: To assess the comparability of searches conducted on two publicly available tobacco industry document collections: hard copies housed and maintained by a neutral party in the Minnesota Depository and electronic copies available through tobacco industry maintained websites.

Methods: We conducted a set of searches in Minnesota and then conducted the same searches using the industry websites. We matched documents by Bates number, weeded out duplicates, and coded documents that were unique to either collection as major, minor, or trivial.

Results: Among hundreds of documents produced by several searches, we found only four unique major documents in the Minnesota Depository. By contrast, we found 62 unique major documents using the websites.

Conclusion: These results suggest that researchers can rely on industry websites while waiting for improved access resulting from searching, indexing, and document storage administered by the tobacco control community. Searching the tobacco industry websites is at least as good as searching in Minnesota and may in some instances actually be better. Four smaller subcollections, however, can only be searched by hand in Minnesota.
Tobacco industry manipulation of the hospitality industry to maintain smoking in public places
Authors: Dearlove J V , Bialous S A , Glantz S A
Published: July 2002

Objective:To describe how the tobacco industry used the “accommodation” message to mount an aggressive and effective worldwide campaign to recruit hospitality associations, such as restaurant associations, to serve as the tobacco industry's surrogate in fighting against smoke-free environments.

Methods:We analysed tobacco industry documents publicly available on the internet as a result of litigation in the USA. Documents were accessed between January and November 2001.

Results:The tobacco industry, led by Philip Morris, made financial contributions to existing hospitality associations or, when it did not find an association willing to work for tobacco interests, created its own “association” in order to prevent the growth of smoke-free environments. The industry also used hospitality associations as a vehicle for programmes promoting “accommodation” of smokers and non-smokers, which ignore the health risks of second hand smoke for employees and patrons of hospitality venues.

Conclusion:Through the myth of lost profits, the tobacco industry has fooled the hospitality industry into embracing expensive ventilation equipment, while in reality 100% smoke-free laws have been shown to have no effect on business revenues, or even to improve them. The tobacco industry has effectively turned the hospitality industry into its de facto lobbying arm on clean indoor air. Public health advocates need to understand that, with rare exceptions, when they talk to organised restaurant associations they are effectively talking to the tobacco industry and must act accordingly.
Influence of host and pathogen variables on the efficacy of Phoma herbarum, a potential biological control agent of Taraxacum officinale
Authors: Neumann Silke , Boland Greg J
Published: July 2002

Phoma herbarum Westendorp has been identified as a potential biological weed control agent (BWCA) for Taraxacum officinale Weber in turf. However, host and pathogen variables that influence the efficacy of this BWCA need to be identified to provide more optimal conditions for production and efficacy. In controlled-environment studies, 4-week-old T. officinale plants were significantly more susceptible to P. herbarum than were plants that were 6 and 8 weeks old, nonflowering but mature, budding, or flowering. Mycelial suspensions incited significantly more severe disease than conidia, and 5-day-old mycelial shake cultures incited significantly higher disease than 3-, 7-, 9-, 11-, or 13-day-old cultures. A concentration of 10 to 20% of mycelial fragments in potato dextrose broth (v/v) incited higher disease severity than 0, 40, 60, or 100%. These experiments identified several important host and pathogen variables that influence the efficacy of P. herbarum on T. officinale and established more optimal conditions for production and efficacy of this BWCA.Key words: biological weed control, bioherbicide, mycoherbicide, Taraxacum officinale, dandelion, Phoma herbarum.
A mixed-species yield model for eastern Bering Sea shelf flatfish fisheries
Authors: Spencer Paul D , Wilderbuer Thomas K , Zhang Chang Ik
Published: July 2002

A variety of eastern Bering Sea (EBS) flatfish including yellowfin sole (Limanda aspera), rock sole (Lepidopsetta bilineata), flathead sole (Hippoglossoides elassodon), and Alaska plaice (Pleuronectes quadrituberculatus), co-occur in various degrees in EBS trawl fisheries, impeding attempts to obtain single-species management targets. A further complication is the bycatch of Pacific halibut (Hippoglossus stenolepis); halibut bycatch limits, rather than single-species catch quotas, have been the primary factor regulating EBS flatfish harvest in recent years. To examine bycatch interactions among the EBS flatfish listed above, an equilibrium mixed-species multifishery model was developed. Equilibrium yield curves, scaled by recent average recruitment, are flat topped or asymptotically increasing, reflecting low fishing selectivity during the first several years of life and low growth relative to natural mortality. A linear programming analysis indicated that relaxation of the halibut bycatch constraint at the optimal solution of catch by fishery would produce approximately 20 times more flatfish yield than a similar relaxation of any flatfish catch quota. A strategy for establishing halibut bycatch limits that considers the foregone revenue in the halibut and flatfish trawl fisheries reveals how the choice of halibut bycatch limit is affected by the management goal for the flatfish complex.
Lactoferrin and transferrin: Functional variations on a common structural framework
Authors: Baker Edward N , Baker Heather M , Kidd Richard D
Published: July 2002

Lactoferrin shares many structural and functional features with serum transferrin, including an ability to bind iron very tightly, but reversibly, a highly-conserved three-dimensional structure, and essentially identical iron-binding sites. Nevertheless, lactoferrin has some unique properties that differentiate it: an ability to retain iron to much lower pH, a positively charged surface, and other surface features that give it additional functions. Here, we review the structural basis for these similarities and differences, including the importance of dynamics and conformational change, and specific interactions that regulate iron binding and release.Key words: transferrin, protein structure, dynamics, iron binding.
The physiology of lactoferrin
Authors: Brock Jeremy H
Published: July 2002

This paper reviews our current knowledge of the structure and function of the iron-binding protein lactoferrin. In particular, it attempts to relate the various proposed physiological functions of lactoferrin to its most characteristic biochemical properties, i.e. its ability to bind iron and its highly basic nature. The extent to which various physiological functions can be considered as definitely established is critically reviewed, and suggestions for future research are proposed.Key words: lactoferrin, iron, nutrition, immunology, infection, inflammation.
Cancer prevention by bovine lactoferrin and underlying mechanisms  a review of experimental and clinical studies
Authors: Tsuda Hiroyuki , Sekine Kazunori , Fujita Ken-ichi , Iigo Masaaki
Published: July 2002

In experimental studies, bovine lactoferrin (bLF) has been found to significantly inhibit colon, esophagus, lung, and bladder carcinogenesis in rats when administered orally in the post-initiation stage. Furthermore, concomitant administration with carcinogens resulted in inhibition of colon carcinogenesis, possibly by suppression of phase I enzymes, such as cytochrome P450 1A2 (CYP1A2), which is preferentially induced by carcinogenic heterocyclic amines. Enhancement of the activities of their phase II counterparts, such as glutathione S-transferase might have also played a critical role in post-initiation suppression in a study of tongue carcinogenesis. Anti-metastatic effects were moreover detected when bLF was given intragastrically to mice bearing highly metastatic colon carcinoma 26 cells (Co 26Lu), with apparent enhancing influence on local and systemic immunity. Marked increase in the number of cytotoxic T and NK cells in the mucosal layer of the small intestine and peripheral blood cells was thus found, this in turn enhancing the production of Interleukin 18 (IL-18) and caspase-1 in the epithelial cells of the small intestine, with possible consequent induction of interferon (IFN)-γ positive cells. Furthermore, bLF has been found to exert anti-hepatitis C virus (HCV) activity in a preliminary clinical trial in patients with chronic active hepatitis due to this virus, a main causative factor in hepatocellular carcinoma development in Japanese. More extensive clinical trials are now underway in the National Cancer Center Hospital and other institutes to further explore the preventive potential against colon carcinogenesis.Key words: lactoferrin, chemoprevention, colon, carcinogenesis, metastasis.
Comparative effects of water immersion pretreatment on three different acute pancreatitis models in rats
Authors: Takács Tamás , Rakonczay Jr. Zoltán , Varga Ilona S , Iványi Béla , Mándi Yvette , Boros Imre , Lonovics János
Published: July 2002

Cells respond to stress by upregulating the synthesis of cytoprotective heat shock proteins (HSPs) and antioxidant enzymes. The aim of this study was to compare the effects of cold (CWI) or hot water immersion (HWI) stress on three different acute pancreatitis models (cholecystokinin octapeptide (CCK), sodium taurocholate (TC), and L-arginine (Arg)). We examined the levels of pancreatic HSP60, HSP72, and antioxidants after the water immersion stress. Male Wistar rats were injected with CCK, TC, or Arg at the peak level of pancreatic HSP synthesis, as determined by Western blot analysis. HWI significantly elevated HSP72 expression and CWI significantly increased HSP60 expression in the pancreas. Water immersion stress decreased the levels of pancreatic antioxidants. CWI and HWI pretreatment ameliorated most of the examined laboratory and morphological parameters of CCK-induced pancreatitis. CWI pretreatment decreased pancreatic edema and the serum amylase level; however, the morphological damage was more severe in TC-induced acute pancreatitis. Overall, CWI and HWI pretreatment only decreased the serum cytokine concentrations in Arg-induced pancreatitis. CWI and HWI resulted in differential induction of pancreatic HSP60 and HSP72 and the depletion of antioxidants. The findings suggest the possible roles of HSP60 and (or) HSP72 (but not that of the antioxidant enzymes) in the protection against CCK- and TC-induced acute pancreatitis. Unexpectedly, CWI pretreatment was detrimental to the morphological parameters of TC-induced pancreatitis. It was demonstrated that CWI and HWI pretreatment only influenced cytokine synthesis in Arg-induced pancreatitis.Key words: heat shock proteins, water immersion, cholecystokinin octapeptide, sodium taurocholate, L-arginine, pancreatitis.
Sampling variance as a function of single-increment size for estimation of bitumen in an oil-sand core
Authors: Gao Zhi , Kratochvil Byron
Published: July 2002

The relationship between sampling variance and single-increment size for bitumen content in oil sand was investigated for a previously collected data set of 1468 contiguous 1-cm2 IR measurements on a 15-m core. A variogram study showed that bitumen in the 15-m core is highly regionalized with a range of influence of 20 cm. For increment sizes lower than this range, the sampling variance as a function of increment size fits a logarithmic function but does not fit Visman's reciprocal function, which was also confirmed for a second oil-sand core with a range of influence of 100 cm. Visman's equation does, however, give good results for larger increment sizes. Computer randomization of the data reveals that Visman's equation is valid for either local or overall random distributions. Characterization by fractal dimension showed that Visman's equation is applicable to populations with higher fractal dimensions (equal or close to 2), whereas a logarithmic relationship is more applicable to populations with lower fractal dimensions.Key words: Sampling, geostatistics, variogram, Visman's equation, oil sand.
Growth, morphology, and cold hardiness of Chamaecyparis nootkatensis seedlings originating from an abbreviated reproductive cycle
Authors: Cherry Marilyn L , El-Kassaby Yousry A
Published: July 2002

A common garden study investigated growth, morphology, and cold hardiness of yellow-cedar (Chamaecyparis nootkatensis (D. Don) Spach) seedlings originating from seed that had matured at an accelerated rate. This early maturing seed, produced at a low-elevation southern Vancouver Island seed orchard, was known to have similar germinability and seedling morphology as high-elevation normally maturing seeds. Population differences in 3-year-old seedlings were evident only in shoot harvest index (ratio of stem/shoot dry weight). The amount of stem elongation that occurred prior to the formation of secondary foliage (juvenile height) and harvest index were weakly correlated with source elevation at which maternal parents were developed. Traits that exhibited no discernable differences between progeny from early maturing seed and the control normally maturing seed included midwinter cold hardiness testing and selected measures of shoot morphology and growth. The control seedlings had significantly less height growth prior to the transition of primary foliage to secondary foliage formation than did the seedlings originating from early maturing seed.
PREDICATE BOUNDEDNESS OF LINEAR MONADIC DATALOG IS IN PSPACE
Authors: Meyden Ron van der
Published: July 2002

Datalog programs, are a special case of logic programs without function symbols. Detection of boundedness permits Datalog programs to be optimized by the elimination of recursion. To determine whether a predicate is bounded in a Datalog program is known to be undecidable. However, previous work (Cosmadakis et al., 20th ACM Symposium on the Theory of Computing, 1988) has show that for monadic Datalog, this problem is decidable, with upper and lower bounds of EXPSPACE and PSPACE respectively for linear monadic programs. We establish that predicate boundedness for linear monadic programs is in fact in PSPACE, yielding a tight bound for this problem.a
FUNCTIONS OF MARKOV PROCESSES AND ALGEBRAIC MEASURES
Authors: FANNES M. , NACHTERGAELE B. , SLEGERS L.
Published: July 2002

We introduce a class of translation-invariant measures on the set {0, …, q−1}ℤ determined by a set of q d-dimensional matrices. They are algebraic in the sense that their densities are obtained by applying a functional to products of the defining matrices. Positivity of probabilities is assured by assuming a positivity structure on the algebra of defining matrices. Restricting attention to the usual positivity notion of positive matrix elements, a detailed analysis leads to a canonical representation theorem that solves the parametrization problem. Furthermore, we show that the class of algebraic measures coincides with the class of functions of Markov processes with finite state spaces. Our main result consists in the detailed study of the asymptotics of the conditional probabilities from which we derive a formula for the mean entropy.
STATIONARY PHASE, QUANTUM MECHANICS AND SEMI-CLASSICAL LIMIT
Authors: REZENDE JORGE
Published: July 2002

A method of stationary phase for the normalized-oscillatory integral on Hilbert space is developed in the case where the phase function has a finite number of critical points which are non-degenerate. Applications to the Feynman path integral and the semi-classical limit of quantum mechanics are given.
Hilbert C*-Bimodules Over Commutative C*-Algebras and an Isomorphism Condition for Quantum Heisenberg Manifolds
Authors: Abadie Beatriz , Exel Ruy
Published: July 2002

A study of Hilbert C*-bimodules over commutative C*-algebras is carried out and used to establish a sufficient condition for two quantum Heisenberg manifolds to be isomorphic.
ARITHMETIC ON A QUINTIC THREEFOLD
Authors: CONSANI CATERINA , SCHOLTEN JASPER
Published: July 2002

This paper investigates some aspects of the arithmetic of a quintic threefold in Pr 4 with double points singularities. Particular emphasis is given to the study of the L-function of the Galois action ρ on the middle ℓ-adic cohomology. The main result of the paper is the proof of the existence of a Hilbert modular form of weight (2, 4) and conductor 30, on the real quadratic field [Formula: see text], whose associated (continuous system of) Galois representation(s) appears to be the most likely candidate to induce the scalar extension [Formula: see text]. The Hilbert modular form is interpreted as a common eigenvector of the Brandt matrices which describe the action of the Hecke operators on a space of theta series associated to the norm form of a quaternion algebra over [Formula: see text] and a related Eichler order.
GENERATION OF COLORED NOISE
Authors: BARTOSCH LORENZ
Published: July 2002

In this work, we describe a simple Markovian algorithm to generate a typical sample path of colored noise described by an Ornstein–Uhlenbeck process. The algorithm works equally well to simulate a real or complex disorder potential with exponentially decaying covariance and higher correlation functions given by Wick's theorem. As an input, we only need independent Gaussian random numbers which can easily be generated by the well-known Box–Muller algorithm. Finally, we discuss an alternative method which can also be used to generate non-Gaussian colored noise.
SMART CARDS: DISTRIBUTED COMPUTING WITH $5 DEVICES
Authors: SIEGELIN CHRISTOPH , CASTILLO LAURENT , FINGER ULRICH
Published: July 2002

Smart cards are highly successful thanks to their unique combination of mobility and security. Based upon a single-chip microcontroller with volatile and non-volatile memories, a smart card implementes a small computer system that is very portable (credit card size), easy to use, and extremely resistant against external attacks.

However, today's smart cards use proprietary protocols, application schemes, and development tools. This is due to the limitations of current technology, and it leads to situation of "splendid isolation" where smart cards are not being regarded as an integral part of the overall IT architecture.

In this paper, we describe recent research towards "next generation" smart cards. It combines an advanced programming language (Java), novel hardware architectures that provide the required "MIPS budget" (RISC 32 bit), as well as an implementation of key Internet protocols (IP, HTTP) on smart cards.

As a result, we show how smart cards can be seamlessly integrated within a distributed computing environment.
CONSISTENCY OF THE HYBRID REGULARIZATION WITH HIGHER COVARIANT DERIVATIVE AND INFINITELY MANY PAULI–VILLARS
Authors: NITTOH KOH-ICHI
Published: July 2002

We study the regularization and renormalization of the Yang–Mills theory in the framework of the manifestly invariant formalism, which consists of a higher covariant derivative with an infinitely many Pauli–Villars fields. Unphysical logarithmic divergence, which is the problematic point on the Slavnov method, does not appear in our scheme, and the well-known value of the renormalization group functions are derived. The cancellation mechanism of the quadratic divergence is also demonstrated by calculating the vacuum polarization tensor of the order of Λ0 and Λ-4. These results are the evidence that our method is valid for intrinsically divergent theories and is expected to be available for the theory which contains the quantity depending on the space–time dimensions, like supersymmetric gauge theories.
RECENT RESULTS USING THE OVERLAP DIRAC OPERATOR
Authors: NARAYANAN RAJAMANI
Published: July 2002

I derive the overlap Dirac operator starting from the overlap formalism, discuss the numerical hurdles in dealing with this operator and present ways to overcome them.
WEYL ORDERING FOR ENTANGLED STATE REPRESENTATION
Authors: FAN HONGYI , FAN YUE
Published: July 2002

We derive a new Weyl ordering operator formula which recasts given operators into Weyl ordering. In so doing, the Weyl ordering formulation of the entangled state representation is obtained, which turns out to be the Weyl ordered Dirac δ-operator functions. The Weyl ordering of the Wigner operator and squeezing operator in entangled state representation are also deduced.
ACCEPTANCE DEPENDENCE OF FLUCTUATION IN PARTICLE MULTIPLICITY
Authors: MAHAPATRA D. P. , MOHANTY B. , PHATAK S. C.
Published: July 2002

The effect of limiting the acceptance in rapidity on event-by-event multiplicity fluctuations in nucleus–nucleus collisions has been investigated. Our analysis shows that the multiplicity fluctuations decrease when the rapidity acceptance is decreased. We explain this trend by assuming that the probability distribution of the particles in the smaller acceptance window follows binomial distribution. Following a simple statistical analysis, we conclude that the event-by-event multiplicity fluctuations for full acceptance are likely to be larger than those observed in the experiments, since the experiments usually have detectors with limited acceptance. We discuss the application of our model to simulated data generated using VENUS, a widely used event generator in heavy-ion collisions. We also discuss the results from our calculations in the presence of dynamical fluctuations and possible observation of these in the actual data.
QUANTUM COHERENCE OF SUPERLATTICES IN TRIANGLE-WAVE ELECTRIC FIELDS
Authors: LIU HAI-FENG , ZHAO XIAN-GENG
Published: July 2002

The problem of coherent motion of an electron in a long period superlattice driven by a triangle-wave electric field is studied. Exact solutions for the amplitude propagators, the field-induced polarization, the mean-square displacement, and the quasienergy spectrum of any initial distribution and long-range hopping coupling are obtained generally. Total collapse of the quasienergy spectrum is found to take place at certain field parameters, which leads to the transition between localization and delocalization. The transport property of the system is also investigated.
TEMPERATURE AND DOPING DEPENDENCE OF ANDREEV REFLECTION IN Au/La2-XSrxCuO4 POINT-CONTACT JUNCTIONS
Authors: GONNELLI R. S. , CALZOLARI A. , DAGHERO D. , NATALE L. , UMMARINO G. A. , STEPANOV V. A. , FERRETTI M.
Published: July 2002

We performed point-contact experiments on high-quality La 2-x Sr x CuO 4 polycrystalline samples with 0.116 ≤ x ≤ 0.186 by using very sharp Au tips (~ 2μ m of diameter). In most cases we observed conductance curves indicating the occurrence of Andreev reflection. The stability of the contact allowed us to study the temperature dependence of these curves up to Tc. The well reproducible results give no evidence of a pseudogap even in the underdoped samples. We fitted the curves at various temperatures by using the generalized BTK model by Tanaka and Kashiwaya allowing for different symmetries of the order parameter, and we obtained the best fit in the (s+d)-wave case. All the symmetries give similar values of the isotropic component of the gap Δ is , which, at low temperature, is always greater than the anisotropic one Δ an and has a different behaviour in temperature. In the overdoped region, Δ is obtained from Andreev reflection almost coincides with the gap determined by quasiparticle tunneling or ARPES. In the under-doped regime the Andreev gap decreases with x, while, following recent measurements, the gap measured by ARPES rapidly increases at the lowering of x. These results seem to confirm in LSCO the hypothesis, recently appeared in literature, of the existence of two distinct energy scales, one associated with the pair formation and the other related to the achievement of the phase coherence in the condensate.
LOCALIZATION LENGTH IN THE COOPER PROBLEM WITH DISORDER
Authors: ARAÚJO M. A. N.
Published: July 2002

We study the localization properties of a bound state of two electrons in the presence of a Fermi sea of normal electrons which are Anderson localized due to disorder. We describe the bound state as in the s-wave Cooper problem. The localization length of the pair depends on its dispersion relation for small momenta relative to the Fermi surface. Expressions for the pair localization length are derived, for both one and two spatial dimensions, in the limit of large single-particle localization length. In one dimensional we find that there is no considerable enhancement of the pair localization length (L c2 ) over that of a single electron (L c ). In two dimensional there is a large enhancement in the limit of large L c . In three dimensional the pair dispersion relation is obtained in both diffusive and (single-particle) localized regimes and the implications on localization are discussed. In this case the mobility edge of the pair is located below the single-electron mobility edge.
PHASE TRANSITION IN LAYERED PEROVSKITE LIKE MANGANATE Ca3Mn2O7 UNDER HIGH PRESSURE
Authors: ZHU J. L. , CHEN L. C. , YU R. C. , LI F. Y. , LIU J. , JIN C. Q.
Published: July 2002

In situ high pressure energy dispersive X-ray diffraction measurements on layered perovskite-like manganate Ca 3 Mn 2 O 7 under pressures up to 35 GPa have been performed by using diamond anvil cell with synchrotron radiation. The results show that the structure of layered perovskite-like manganate Ca 3 Mn 2 O 7 is unstable under pressure due to the easy compression of NaCl-type blocks. The structure of Ca 3 Mn 2 O 7 underwent two phase transitions under pressures in the range of 0~35 GPa. One was at about 1.3 GPa with the crystal structure changing from tetragonal to orthorhombic. The other was at about 9.5 GPa with the crystal structure changing from orthorhombic back to another tetragonal.
INFRARED ABSORPTION BY EXCITONS IN CUPROUS OXIDE
Authors: GÖPPERT M. , BECKER R. , MAIER C. , JÖRGER M. , JOLK A. , KLINGSHIRN C.
Published: July 2002

We report on the first observation of the 1s to 2p exciton transition in a direct gap semiconductor. Cuprous oxide is well known for its excitonic features which provide a model case for the theory of Wannier excitons. In our pump-probe experiment we measured the infrared transmission of cuprous oxide with the without Ar +-laser illumination. The observed photo-induced absorption line in the differential transmission spectra at 126 meV is assigned to the excitonic transition from 1s to 2p exciton levels i.e. to the analog of the Lyman series in atomic hydrogen. From the dependence of the integrated photo-induced absorption on the pump laser intensity we determine the lifetime of the paraexciton τ p ≈0.3 ms. We also studied the influence of the pump laser on the phonon absorption band in the mid-infrared. Its observed shift to lower energies with increasing pump laser intensity can be explained by heating of the samples.
CRYSTAL STRUCTURE AND GAS SENSING PROPERTIES OF Cu-DOPED ZINC OXIDE
Authors: ONG CHIN HOCK , WANG JIAN HUI , GONG HAO , CHAN H. S. O.
Published: July 2002

Copper doped Zinc Oxide thin films are prepared by RF magnetron sputtering. The films are characterized by using X-ray diffraction (XRD), scanning electron microscopy (SEM), atomic force microscopy (AFM), and other techniques. It is found that the films are composed of nano-crystal grains with typical columnar structure. The structural properties, such as preferred orientation, residual strains exist in the films, and grains size were studied. Moreover, the porous structure that related with the surface morphology of the films was discussed as it has relationship with the gas sensing property. Gas sensing property of these films was studied with the understanding of structural properties. The films were tested with NO gas. The sensitivity of the films was studied through the discussions of films structures.
QUANTUM FIELD THEORY RENORMALIZATION GROUP APPROACH TO SELF-ORGANIZED CRITICAL MODELS: THE CASE OF RANDOM BOUNDARIES
Authors: VOLCHENKOV D. , BLANCHARD PH. , CESSAC B.
Published: July 2002

The long time and large scale asymptotic behavior for a stochastic problem related to self-organized critical (SOC) models is studied in the framework of advanced quantum field theory renormalization group (RG) method. The threshold condition and time scale separation between the slow dynamics of energy injection and the fast dynamics of avalanches (relaxation) are taken into account in the model. Herewith, the reciprocal correlation time at wavenumber k scales as tc(k) ∝ k-2+2η with some phenomenological parameter η > 0 corresponding to the anomalous diffusion coefficient z = 2(1 - η). The quantum field theory corresponding to the nonlinear stochastic problem is multiplicatively renormalizable and has an infinite number of coupling constants. The RG equations have a two-dimensional manifold of fixed points. Some of them relate to the stable asymptotic solutions and stipulate a general scaling with the critical dimensions of time Δ[t] = -2 + 2η and the energy field Δ[E] = d/2 - 3(1 - η). Possible corrections to the leading asymptotic behavior are discussed.
SUPERFLUIDITY IN SEMI-LOCALIZED 2D ELECTRON SYSTEM WITH CIRCULAR MOLECULAR ORBITS
Authors: SUGAHARA MASANORI , BOGOLUBOV NIKOLAI N.
Published: July 2002

Recently discovered new type of high temperature superconductors have circular molecular orbits in each unit site of 2D s/p electron system. We discuss a new model of superconductivity caused by the correlated state of electrons in the 2D interconnection of circular orbits. This model gives an estimation of the superfluidity transition temperature: T c ≈ 70-200  K for fcc C 60, and T c ≈50-150  K for MgB2 .
Effect of Superconducting Fluctuations in Tunneling Conductance Spectra
Authors: Cucolo A. M. , Cuoco M. , Noce C. , Varlamov A. A.
Published: July 2002

The influence of superconducting fluctuations on the conductance spectra of superconductor-insulator-normal metal (S-I-N) tunnel junctions is considered. We discuss how the tunneling conductance is affected as the strength of fluctuations is changed close to the superconducting critical transition.
SELF-ORGANIZED MIXED-PHASE PERCOLATION MODEL OF HIGH-TEMPERATURE SUPERCONDICTIVITY
Authors: PHILLIPS J.
Published: July 2002

The traditional theory of superconductivity is based on the effective medium approximation which is suitable for normal metals and their alloys. For high-temperature superconductors (HTSC) the author has developed an entirely different theory, based on percolation of metallic filaments in a semiconductive matrix. The new theory gives excellent explanations for the many anomalous properties of HTSC which cannot be explained by effective medium theories. The filamentary structure is produced by self-organized percolation in an intermediate phase which has a characteristic phase diagram, whose features are quite general and which has been observed not only to describe HTSC, but also the insulator-metal transition in semiconductor impurity bands.
AN EXPLICIT DESCRIPTION OF AXISYMMETRIC VESICLES IN TERMS OF ELLIPTIC FUNCTION
Authors: YU DELONG , WANG SHIKUN
Published: July 2002

The equilibrium shape of a class of axisymmetric vesicles, first discovered by Naito et al. (Phys. Rev. Lett.74, 4345 (1995)), is given explicit coordinate description in terms of elliptic function. The elliptic function description reveals that there are actually two branches of non-congruent shapes of axisymmetric vesicles associated with the Gauss map of the vesicles considered.
USING A STATISTICAL LANGUAGE MODEL TO IMPROVE THE PERFORMANCE OF AN HMM-BASED CURSIVE HANDWRITING RECOGNITION SYSTEM
Authors: MARTI U.-V. , BUNKE H.
Published: July 2002

In this paper, a system for the reading of totally unconstrained handwritten text is presented. The kernel of the system is a hidden Markov model (HMM) for handwriting recognition. This HMM is enhanced by a statistical language model. Thus linguistic knowledge beyond the lexicon level is incorporated in the recognition process. Another novel feature of the system is that the HMM is applied in such a way that the difficult problem of segmenting a line of text into individual words is avoided. A number of experiments with various language models and large vocabularies have been conducted. The language models used in the system were also analytically compared based on their perplexity.
PERIODIC ORBITS OF THE LORENZ SYSTEM THROUGH PERTURBATION THEORY
Authors: PALACIÁN J. , YANGUAS P.
Published: July 2002

Different transformations are applied to the Lorenz system with the aim of reducing the initial three-dimensional system into others of dimension two. The symmetries of the linear part of the system are determined by calculating the matrices which commute with the matrix associated to the linear part. These symmetries are extended to the whole system up to an adequate order by using Lie transformations. After the reduction, we formulate the resulting systems using the invariants associated to each reduction. At this step, we calculate for each reduced system the equilibria and their stability. They are in correspondence with the periodic orbits and invariant sets of the initial system, the stability being the same.
COLLECTIVE MODES OF THREE COUPLED RELAXATION OSCILLATORS: THE INFLUENCE OF DETUNING
Authors: RUWISCH DIETMAR , BODE MATHIAS , VOLKOV DENIS , VOLKOV EVGENII
Published: July 2002

The dynamics of a ring of three relaxation oscillators symmetrically coupled in the slow variable is considered both experimentally and by means of numerical simulations. It is shown that apart from the synchronous oscillation the basic set of periodic attractors typical for identical oscillators is not essentially affected by a small detuning. However, detuning creates a large set of new collective modes which are characterized by larger system periods and a variety of phase relations between the oscillators. Comparisons of the experimental data with different oscillator models reveal that the results do not crucially depend on the specific features of the models and possible experimental uncertainties.
CONDITIONS FOR GLOBAL SYNCHRONIZATION IN LATTICES OF CHAOTIC ELEMENTS WITH LOCAL CONNECTIONS
Authors: ANDREYEV YURI V. , DMITRIEV ALEXANDER S.
Published: July 2002

We investigate the phenomena on the edge of spatially homogeneous chaotic mode and spatiotemporal chaos in a lattice of chaotic 1D maps with local connections. We show that spatially homogeneous chaotic mode cannot exist in a lattice with local connections if the Lyapunov exponent λ of the isolated chaotic map is greater than some critical positive value. We propose a few schemes that make spatial synchronization possible in large lattices. If the idea of only local connections is abandoned, the number of connections necessary for synchronization dramatically decreases to three per node. We also propose a model of a lattice with an external pacemaker, where we find a spatially homogeneous mode synchronous with the pacemaker, as well as different from the pacemaker mode.
EXPERIMENTAL IMPROVEMENT OF CHAOTIC SYNCHRONIZATION DUE TO MULTIPLICATIVE TIME-CORRELATED GAUSSIAN NOISE
Authors: PÉREZ-MUÑUZURI V. , LORENZO M. N.
Published: July 2002

The effect of time-correlated zero-mean Gaussian noise on chaotic synchronization is analyzed experimentally in small-size arrays of Chua's circuits. Depending on the correlation time, an improvement of the synchronization is found for different values of the noise amplitude and coupling diffusion between circuits.
POLYNOMIAL CLOSURE AND TOPOLOGY
Authors: STEINBERG BENJAMIN
Published: July 2002

Suppose H is a pseudovariety of groups. This paper studies the pseudovariety of monoids corresponding to the variety of languages generated by the polynomial closure of the variety of H-languages (which is shown to be J*H via a short syntactic argument) and the pseudovariety of ordered monoids corresponding to the polynomial closure of the variety of H-languages. We also explore alternative descriptions of these pseudovarieties under additional hypotheses. Decidability results are given.

In addition, we study the positive varieties of pro-V open and closed recognizable sets for a pseudovariety V of monoids. In particular, we obtain a basis of ordered pseudoidentities for such positive varieties. For pseudovarieties of groups H, we relate these positive varieties to the polynomial closure of the H-languages. Again, decidability results are obtained.
A NOTE ON LIST LANGUAGES
Authors: BERSTEL JEAN , BOASSON LUC
Published: July 2002

We prove that fair list languages are not closed under reversal. This answers a question of a paper by Breveglieri. We then introduce a "strict" parallel product that defines a family closed under reversal; we show that this product properly generalizes the parallel product.
ON THE COUNTING OF COLORED TANGLES
Authors: ZINN-JUSTIN PAUL , ZUBER JEAN-BERNARD
Published: July 2002

The connection between matrix integrals and links is used to define matrix models which count alternating tangles n which each closed loop is weighted with a factor n, i.e. may be regarded as decorated with n possible colors. For n=2, the corresponding matrix integral is that recently solved in the study of the random lattice six-vertex model. The generating function of alternating 2-color tangle is provided in terms of elliptic functions, expanded to 16-th order (16 crossings) and its asymptotic behaviors is given.
THE CAUSAL INTERPRETATION OF QUANTUM MECHANICS AND THE SINGULARITY PROBLEM AND TIME ISSUE IN QUANTUM COSMOLOGY
Authors: DE BARROS J. ACACIO , PINTO-NETO N.
Published: July 2002

We apply the causal interpretation of quantum mechanics to homogeneous quantum cosmology and show that the quantum theory is independent of any time-gauge choice and there is no issue of time. We exemplify this result by studying a particular minisuperspace model where the quantum potential driven by a prescribed quantum state prevents the formation of the classical singularity, independently on the choice of the lapse function. Hence, within the framework of the causal interpretation of quantum cosmology, the fast-slow-time gauge conjecture is incorrect for homogeneous minisuperspace models.
HIGHER DERIVATIVE THEORY WITH VISCOSITY
Authors: PAUL B. C. , MUKHERJEE S. , BEESHAM A.
Published: July 2002

Cosmological solutions in a higher derivative theory have been obtained with an imperfect fluid. We consider both power law and exponential models of the early universe. We discuss cosmological models in the Eckart, truncated and full causal theories. In the full-causal theory, we distinguish between two cases, one with the temperature obeying a power law behavior and the other relaxing this assumption. The exponential solution permits a realistic scenario when the behavior of the temperature is not of the power-law type.
CORRECT STATEMENT OF A SCATTERING PROBLEM FOR QUANTUM CHARGED SCALAR PARTICLES ON THE REISSNER–NORDSTRÖM BLACK HOLES
Authors: FIRSOVA N. E.
Published: July 2002

We study a correct statement of the scattering problem arising for quantum charged scalar particles on the Reissner–Nordström black holes when taking into account the own electric field of black hole. The elements of the corresponding S-matrix are explored in the form convenient to physical applications and for applying numerical methods. Some further possible issues are outlined.
DILATION DARK MATTER IN VAIDYA–de SITTER SPACETIME
Authors: CRISTINA NEACSU MARIA
Published: July 2002

The exterior of a relativistic star can be modeled with the Vaidya radiating metric. It is started from the generalized Vaidya metric that allows a type II fluid and studied the conditions of generating new analytical solutions of the Einstein's field equations. It is shown that the mass parameter solution gives the classical de Sitter universe in the static case and the extended de Sitter metric coupled with a dilation scalar field in the time-dependent case. It is concluded that in the time-dependent case the atmosphere of a relativistic star consists on an anisotropic string fluid coupled with a dark matter null fluid and interpreted the scalar field as the particle that produces the dark matter.
MICROSCOPIC COEFFICIENTS FOR THE QUANTUM MASTER EQUATION OF A FERMI SYSTEM
Authors: STEFANESCU ELIADE , SANDULESCU AUREL
Published: July 2002

In a previous paper, we derived a master equation for fermions, of Lindblad's form, with coefficients depending on microscopic quantities. In this paper, we study the properties of the dissipative coefficients taking into account the explicit expressions of: (a) the matrix elements of the dissipative potential, evaluated from the condition that, essentially, this potential induces transitions among the system eigenstates without significantly modifying these states, (b) the densities of the environment states according to the Thomas–Fermi model, and (c) the occupation probabilities of these states taken as a Fermi–Dirac distribution. The matrix of these coefficients correctly describes the system dynamics: (a) for a normal, Fermi–Dirac distribution of the environment population, the decays dominate the excitation processes; (b) for an inverted (exotic) distribution of this population, specific to a clustering state, the excitation processes are dominant.