bluuebunny/crossref_metadata_2025 huggingface dataset:
Temporal association between serum prolactin concentration and exposure to styrene
Authors: Luderer U , Tornero-Velez R , Shay T , Rappaport S , Heyer N , Echeverria D
Published: March 2004

Background:Previous studies have suggested that occupational exposure to styrene is associated with increased serum levels of the anterior pituitary hormone prolactin (PRL).

Aims:To test the hypotheses that: (1) the effect of styrene exposure on PRL secretion is an acute effect, not a subchronic or chronic effect; (2) blood styrene, as a measure of absorbed dose, is a stronger predictor of serum PRL level than personal breathing zone air styrene concentration.

Methods:Subjects were recruited from 17 workplaces in the reinforced plastics industry. Personal breathing zone air styrene, whole blood styrene, and serum PRL were measured during one to three sessions, approximately one year apart. Linear multiple regression was used to model the relations between acute (air styrene or blood styrene obtained at same time as PRL), subchronic (average air or blood styrene over two or three sessions), and chronic (years of work in industry or facility times average air styrene over all sessions) indices of styrene exposure and serum PRL.

Results:Acute blood styrene concentration was the strongest predictor of serum PRL concentration, with the model predicting a 2.06-fold increase in PRL (95% CI 1.11 to 3.84) for every 10-fold increase in blood styrene. Serum PRL tended to increase with increasing styrene exposure in both men and women; however, women tended to have higher PRL levels. For women, the change in blood styrene between sessions 1 and 2 was a significant predictor of the change in serum PRL between sessions.

Conclusions:Results confirm that styrene exposure enhances serum PRL concentrations and support an acute effect of styrene on PRL secretion.
Respiratory symptoms and airflow limitation in asphalt workers: Table 1
Authors: Randem B G , Ulvestad B , Burstyn I , Kongerud J
Published: March 2004

Background:Asphalt workers are exposed to bitumen fume and vapour, and to exhaust from engines and passing traffic.

Aims:To assess the occurrence of respiratory symptoms and signs of airflow limitations in a group of asphalt workers.

Methods:All 64 asphalt workers and a reference group of 195 outdoor construction workers from the same company participated in a cross-sectional study. Spirometric tests and a questionnaire on respiratory symptoms and smoking habits were administered. Respiratory symptoms and lung function were adjusted for age and smoking.

Results:The FEV1/FVC% ratio was significantly lower in the asphalt workers than in the referents. Symptoms of eye irritation, chest tightness, shortness of breath on exertion, chest wheezing, physician diagnosed asthma, and chronic obstructive pulmonary disease (COPD) were all significantly more prevalent among the asphalt workers.

Conclusion:In asphalt workers there is an increased risk of respiratory symptoms, lung function decline, and COPD compared to other construction workers.
Particulate air pollution and panel studies in children: a systematic review
Authors: Ward D J , Ayres J G
Published: March 2004

Background:Panel studies have been used to investigate the short term effects of outdoor particulate air pollution across a wide range of environmental settings.

Aims:To systematically review the results of such studies in children, estimate summary measures of effect, and investigate potential sources of heterogeneity.

Methods:Studies were identified by searching electronic databases to June 2002, including those where outcomes and particulate level measurements were made at least daily for ⩾8 weeks, and analysed using an appropriate regression model. Study results were compared using forest plots, and fixed and random effects summary effect estimates obtained. Publication bias was considered using a funnel plot.

Results:Twenty two studies were identified, all except two reporting PM10(24 hour mean) >50 μg.m−3. Reported effects of PM10on PEF were widely spread and smaller than those for PM2.5(fixed effects summary: −0.012v−0.063 l.min−1per μg.m−3rise). A similar pattern was evident for symptoms. Random effects models produced larger estimates. Overall, in between-study comparisons, panels of children with diagnosed asthma or pre-existing respiratory symptoms appeared less affected by PM10levels than those without, and effect estimates were larger where studies were conducted in higher ozone conditions. Larger PM10effect estimates were obtained from studies using generalised estimating equations to model autocorrelation and where results were derived by pooling subject specific regression coefficients. A funnel plot of PM10results for PEF was markedly asymmetrical.

Conclusions:The majority of identified studies indicate an adverse effect of particulate air pollution that is greater for PM2.5than PM10. However, results show considerable heterogeneity and there is evidence consistent with publication bias, so limited confidence may be placed on summary estimates of effect. The possibility of interaction between particle and ozone effects merits further investigation, as does variability due to analytical differences that alter the interpretation of final estimates.
Mortality of workers exposed to ethylene oxide: extended follow up of a British cohort
Authors: Coggon D , Harris E C , Poole J , Palmer K T
Published: March 2004

Aims:To obtain further information about the risks of cancer associated with occupational exposure to ethylene oxide

Methods:Follow up was extended by 13 years for a cohort of 2876 men and women with definite or potential exposure to ethylene oxide in the chemical industry or in hospital sterilising units. Subjects were traced through National Health Service and social security records, and their mortality was compared with that expected from rates in the national population by the person-years method.

Results:Analysis was based on 565 deaths, of which 339 had occurred during the additional period of follow up. Mortality was close to or below expectation for all causes (565 deathsv607.6 expected), all cancers (188v184.2), and for all specific categories of malignancy including stomach cancer (10v11.6), breast cancer (11v13.2), non-Hodgkin’s lymphoma (7v4.8), and leukaemia (5v4.6). All five deaths from leukaemia occurred in the subset of subjects with greatest potential for exposure to ethylene oxide, but even in this group the excess of deaths was small (2.6 expected).

Conclusions:The balance of evidence from this and other epidemiological investigations indicates that any risk of human cancer from ethylene oxide is low, particularly at the levels of occupational exposure that have occurred in Britain over recent decades. This may reflect the capacity of human cells to repair DNA damage caused by the chemical, which is a potent genotoxin and animal carcinogen.
Mortality in a cohort of vermiculite miners exposed to fibrous amphibole in Libby, Montana
Authors: McDonald J C , Harris J , Armstrong B
Published: March 2004

Background:Fibrous tremolite is a widespread amphibole asbestiform mineral, airborne fibres of which constitute an environmental hazard in Libby, Montana, northern California, and elsewhere.

Aims:To determine excess risk from lung cancer, mesothelioma, and all-cause mortality in a cohort of men exposed to tremolite, but no other form of asbestos.

Methods:Mortality by certified cause and various measures of exposure to tremolite and related amphibole fibres was assessed in a cohort of 406 vermiculite mineworkers in Libby, Montana, employed before 1963 and followed until 1999.

Results:Total deaths were: lung cancer 44 (SMR 2.40), non-malignant respiratory disease (NMRD) 51 (SMR 3.09), all causes 285 (SMR 1.27); included among the total were 12 deaths ascribed to mesothelioma (4.21% of all deaths). Adjusted linear increments in relative risks (per 100 f/ml.y), estimated by Poisson regression, were: lung cancer (0.36, 95% CI 0.03 to 1.20), NMRD (0.38, 95% CI 0.12 to 0.96), and all deaths (0.14, 95% CI 0.05 to 0.26).

Conclusions:The all-cause linear model would imply a 14% increase in mortality for mine workers exposed occupationally to 100 f/ml.y or about 3.2% for a general population exposed for 50 years to an ambient concentration of 0.1 f/ml. Amphibole fibres, tremolite in particular, are likely to be disproportionately responsible for cancer mortality in persons exposed to commercial chrysotile, but to what extent cannot be readily assessed.
Reducing absenteeism in hospital cleaning staff: pilot of a theory based intervention
Authors: Michie S , Wren B , Williams S
Published: March 2004

Aims:To develop, pilot, and evaluate a workplace intervention to reduce sickness absence, based on a demand-control-support model of job strain.

Methods:Changes in the working arrangements of hospital cleaning staff were introduced with the aim of increasing their control over work and the support received at work. The study design was quasi-experimental, with 221 cleaning staff in the intervention group and 91 catering staff in the control group. The dependent variable was the difference in percentage monthly sickness absence between the 12 months preceding and following the intervention. Differences in sickness absence between staff groups for each month after the intervention were compared with differences between staff groups for the equivalent month one year prior to it.

Results:There was a significant reduction in the difference in sickness absence rates between the intervention and control group of 2.3% in the six months after the intervention, compared to the six months before. The difference was not maintained at 12 months.

Conclusions:These results suggest that a workplace intervention aimed at increasing control and support at work has a small effect on reducing sickness absence among hospital cleaning staff in the short term. Future research should seek to replicate this effect in larger, experimental studies, analyse postulated mediators of such theory based interventions, and develop interventions that maintain improvement.
ON HIGHER ARTHUR-MERLIN CLASSES
Authors: CAI JIN-YI , CHARLES DENIS , PAVAN A. , SENGUPTA SAMIK
Published: March 2004

We study higher Arthur-Merlin classes defined via several natural probabilistic operators BP, R and coR. We investigate the complexity classes they define, and a number of interactions between these operators and the standard polynomial time hierarchy. We prove a hierarchy theorem for these higher Arthur-Merlin classes involving interleaving operators, and a theorem giving non-trivial upper bounds to the intersection of the complementary classes in the hierarchy.
COLORING ALGORITHMS ON SUBCUBIC GRAPHS
Authors: SKULRATTANAKULCHAI SAN , GABOW HAROLD N.
Published: March 2004

We present efficient algorithms for three coloring problems on subcubic graphs. (A subcubic graph has maximum degree at most three.) The first algorithm is for 4-edge coloring, or more generally, 4-list-edge coloring. Our algorithm runs in linear time, and appears to be simpler than previous ones. The second algorithm is the first randomized EREW PRAM algorithm for the same problem. It uses O(n/ log n) processors and runs in O( log n) time with high probability, where n is the number of vertices of the graph. The third algorithm is the first linear-time algorithm to 5-total-color subcubic graphs. The fourth algorithm generalizes this to get the first linear-time algorithm to 5-list-total-color subcubic graphs. Our sequential algorithms are based on a method of ordering the vertices and edges by traversing a spanning tree of a graph in a bottom-up fashion. Our parallel algorithm is based on a simple decomposition principle for subcubic graphs.
WORD COMPLEXITY AND REPETITIONS IN WORDS
Authors: ILIE LUCIAN , YU SHENG , ZHANG KAIZHONG
Published: March 2004

With ideas from data compression and combinatorics on words, we introduce a complexity measure for words, called repetition complexity, which quantifies the amount of repetition in a word. The repetition complexity of w, R (w), is defined as the smallest amount of space needed to store w when reduced by repeatedly applying the following procedure: n consecutive occurrences uu…u of the same subword u of w are stored as (u,n). The repetition complexity has interesting relations with well-known complexity measures, such as subword complexity, SUB , and Lempel-Ziv complexity, LZ . We have always R (w)≥ LZ (w) and could even be that the former is linear while the latter is only logarithmic; e.g., this happens for prefixes of certain infinite words obtained by iterated morphisms. An infinite word α being ultimately periodic is equivalent to: (i) [Formula: see text], (ii) [Formula: see text], and (iii) [Formula: see text]. De Bruijn words, well known for their high subword complexity, are shown to have almost highest repetition complexity; the precise complexity remains open. R (w) can be computed in time [Formula: see text] and it is open, and probably very difficult, to find fast algorithms.
DICTIONARY LOOK-UP WITHIN SMALL EDIT DISTANCE
Authors: ARSLAN ABDULLAH N. , EĞECIOĞLU ÖMER
Published: March 2004

Let [Formula: see text] be a dictionary consisting of n binary strings of length m each, represented as a trie. The usual d-query asks if there exists a string in [Formula: see text] within Hamming distance d of a given binary query string q. We present a simple algorithm to determine if there is a member in [Formula: see text] within edit distanced of a given query string q of length m. The method takes time O(dmd+1) in the RAM model, independent of n, and requires O(dm) additional space. We also generalize the results for the case of the problem over a larger alphabet.
ON THE MINIMAL POLYNOMIAL OF A MATRIX
Authors: HOANG THANH MINH , THIERAUF THOMAS
Published: March 2004

We investigate the complexity of the degree and the constant term of the minimal polynomial of a matrix. We show that the degree of the minimal polynomial is computationally equivalent to the matrix rank.

We compare the constant term of the minimal polynomial with the constant term of the characteristic polynomial. The latter is known to be computable in the logspace counting class GapL. We show that if this holds for the minimal polynomial as well, then the exact counting in logspace class C=L is closed under complement. Whether C=L is closed under complement is one of the main open problems in this area.

As an application of our techniques we show that the problem of deciding whether a matrix is diagonalizable is complete for AC0(C=L), the AC0-closure ofC=L.
ANALYZING VULNERABILITIES OF CRITICAL INFRASTRUCTURES USING FLOWS AND CRITICAL VERTICES IN AND/OR GRAPHS
Authors: DESMEDT YVO , WANG YONGGE
Published: March 2004

AND/OR graphs and minimum-cost solution graphs have been studied extensively in artificial intelligence (see, e.g., Nilsson [14]). Generally, the AND/OR graphs are used to model problem solving processes. The minimum-cost solution graph can be used to attack the problem with the least resource. However, in many cases we want to solve the problem within the shortest time period and we assume that we have as many concurrent resources as we need to run all concurrent processes. In this paper, we will study this problem and present an algorithm for finding the minimum-time-cost solution graph in an AND/OR graph. We will also study the following problems which often appear in industry when using AND/OR graphs to model manufacturing processes or to model problem solving processes: finding maximum (additive and non-additive) flows and critical vertices in an AND/OR graph. A detailed study of these problems provide insight into the vulnerability of complex systems such as cyber-infrastructures and energy infrastructures (these infrastructures could be modeled with AND/OR graphs). For an infrastructure modeled by an AND/OR graph, the protection of critical vertices should have highest priority since terrorists could defeat the whole infrastructure with the least effort by destroying these critical points. Though there are well known polynomial time algorithms for the corresponding problems in the traditional graph theory, we will show that generally it is NP-hard to find a non-additive maximum flow in an AND/OR graph, and it is both NP-hard and coNP-hard to find a set of critical vertices in an AND/OR graph. We will also present a polynomial time algorithm for finding a maximum additive flow in an AND/OR graph, and discuss the relative complexity of these problems.
IMPROVED BOUNDS ON THE NUMBER OF AUTOMATA ACCEPTING FINITE LANGUAGES
Authors: DOMARATZKI MICHAEL
Published: March 2004

We improve the known bounds on the number of pairwise non-isomorphic minimal deterministic finite automata (DFAs) on n states which accept finite languages. The lower bound constructions are iterative approaches which yield recurrence relations.
GEM- AND CO-GEM-FREE GRAPHS HAVE BOUNDED CLIQUE-WIDTH
Authors: BRANDSTÄDT ANDREAS , LE HOÀNG-OANH , MOSCA RAFFAELE
Published: March 2004

The P4 is the induced path of four vertices. The gem consists of a P4 with an additional universal vertex being completely adjacent to the P4, and the co-gem is its complement graph. Gem- and co-gem-free graphs generalize the popular class of cographs (i. e. P4-free graphs). The tree structure and algebraic generation of cographs has been crucial for several concepts of graph decomposition such as modular and homogeneous decomposition. Moreover, it is fundamental for the recently introduced concept of clique-width of graphs which extends the famous concept of treewidth. It is well-known that the cographs are exactly those graphs of clique-width at most 2. In this paper, we show that the clique-width of gem- and co-gem-free graphs is at most 16.
REAL-TIME FACIAL POSE IDENTIFICATION WITH HIERARCHICALLY STRUCTURED ML POSE CLASSIFIER
Authors: SUNG JAE-WON , KIM DAIJIN
Published: March 2004

Since pose-varying face images form nonlinear convex manifold in high dimensional image space, it is difficult to model their pose distribution in terms of a simple probabilistic density function. To solve this difficulty, we divide the pose space into many constituent pose classes and treat the continuous pose estimation problem as a discrete pose-class identification problem. We propose to use a hierarchically structured ML (Maximum Likelihood) pose classifiers in the reduced feature space to decrease the computation time for pose identification, where pose space is divided into several pose groups and each group consists of a number of similar neighboring poses. We use the CONDENSATION algorithm to find a newly appearing face and track the face with a variety of poses in real-time. Simulation results show that our proposed pose identification using the hierarchically structured ML pose classifiers can perform a faster pose identification than conventional pose identification using the flat structured ML pose classifiers. A real-time facial pose tracking system is built with high speed hierarchically structured ML pose classifiers.
CHINESE WORD SEARCHING IN IMAGED DOCUMENTS
Authors: LU YUE , TAN CHEW LIM
Published: March 2004

An approach to searching for user-specified words in imaged Chinese documents, without the requirements of layout analysis and OCR processing of the entire documents, is proposed in this paper. A small number of Chinese characters that cannot be successfully bounded using connected component analysis due to larger gaps between elements within the characters are blacklisted. A suitable character that is not included in the blacklist is chosen from the user-specified word as the initial character to search for a matching candidate in the document. Once a matched candidate is found, the adjacent characters in the horizontal and vertical directions are examined for matching with other corresponding characters in the user-specified word, subject to the constraints of alignment (either horizontal or vertical direction) and size similarity. A weighted Hausdorff distance is proposed for the character matching. Experimental results show that the present method can effectively search the user-specified Chinese words from the document images with the format of either horizontal or vertical text lines, or both appearing on the same image.
EFFICIENT CONTOUR DETECTION BASED ON IMPROVED SNAKE MODEL
Authors: SHIH FRANK Y. , ZHANG KAI
Published: March 2004

Active contour model, also called snake, adapts to edges in an image. A snake is defined as an energy minimizing spline – the snake's energy depends on its shape and location within the image. Problems associated with initialization and poor convergence to boundary concavities, however, have limited its utility. In this paper, we present a new external force field, named gravitation force field, for the snake model. We associate this force field with edge preserving smoothing to drive the snake for solving the problems. Our gravitation force field uses gradient values as particles to construct force field in the whole image. This force field will attract the active contour toward the edge boundary. The locations of the initial contour are very flexible, such that they can be very far away from the objects and can be inside, outside, or the mixture. The improved snake can converge toward the object boundary in a fast pace.
CLASSIFYING APPLES BY THE MEANS OF FLUORESCENCE IMAGING
Authors: CODREA MARIUS C. , NEVALAINEN OLLI S. , TYYSTJÄRVI ESA , VANDEVEN MARTIN , VALCKE ROLAND
Published: March 2004

Classification of harvested apples when predicting their storage potential is an important task. This paper describes how chlorophyll a fluorescence images taken in blue light through a red filter, can be used to classify apples. In such an image, fluorescence appears as a relatively homogenous area broken by a number of small nonfluorescing spots, corresponding to normal corky tissue patches, lenticells, and to damaged areas that lower the quality of the apple. The damaged regions appear more longish, curved or boat-shaped compared to the roundish, regular lenticells. We propose an apple classification method that employs a hierarchy of two neural networks. The first network classifies each spot according to geometrical criteria and the second network uses this information together with global attributes to classify the apple. The system reached 95% accuracy using a test material classified by an expert for "bad" and "good" apples.
HOMOGENIZATION OF A NONLINEAR MONOTONE PROBLEM IN AN ANISOTROPIC MEDIUM
Authors: SILI ALI
Published: March 2004

This paper deals with an analysis of a nonlinear monotone conduction problem posed on a medium which we assume to be anisotropic and periodically reinforced by thin fibers also assumed to be anisotropic. We consider the case where the conductivity in the fibers are more important than in the material which surrounds it so that the operator we have to consider loses his uniform ellipticity with respect to the size ε of the period; we then investigate the effect of the anisotropy in the homogenization process.
A MODEL HIERARCHY FOR IONOSPHERIC PLASMA MODELING
Authors: BESSE CHRISTOPHE , DEGOND PIERRE , DELUZET FABRICE , CLAUDEL JEAN , GALLICE GÉRARD , TESSIERAS CHRISTIAN
Published: March 2004

This paper deals with the modeling of the ionospheric plasma. Starting from the two-fluid Euler–Maxwell equations, we present two hierarchies of models. The MHD hierarchy deals with large plasma density situations while the dynamo hierarchy is adapted to lower density situations. Most of the models encompassed by the dynamo hierarchy are classical ones, but we shall give a unified presentation of them which brings a new insight into their interrelations. By contrast, the MHD hierarchy involves a new (at least to the authors) model, the massless-MHD model. This is a diffusion system for the density and magnetic field which could be of great practical interest. Both hierarchies terminate with the "classical" Striation model, which we shall investigate in detail.
FINITE VOLUME APPROXIMATION FOR DEGENERATE DRIFT-DIFFUSION SYSTEM IN SEVERAL SPACE DIMENSIONS
Authors: CHAINAIS-HILLAIRET CLAIRE , PENG YUE-JUN
Published: March 2004

This paper is devoted to a finite volume discretization for multidimensional nonlinear drift-diffusion system. Such system arises in semiconductors modelling and is composed of two degenerate parabolic equations and an elliptic one. We prove the convergence of the finite volume scheme and then the existence of solutions to the problem. Several numerical tests show the efficiency of the method.
ON CHARGED INSULATED METALLIC CLUSTERS
Authors: DIETRICH K. , GARNY M. , POMORSKI K.
Published: March 2004

We determine the wavefunctions and eigen-values of electrons bound to a positively charged mesoscopic metallic cluster covered by an insulating surface layer. The radius of the metal core and the thickness of the insulating surface layer are of the order of a couple of Ångström. We study in particular the electromagnetic decay of externally located electrons into unoccupied internally located states which exhibits a resonance behaviour. This resonance structure has the consequence that the lifetime of the "mesoscopic atoms" may vary by up to 6 orders of magnitude depending on the values of the parameters (from sec to years).
PERIODIC ORBIT THEORY INCLUDING SPIN DEGREES OF FREEDOM
Authors: BRACK MATTHIAS , AMANN CHRISTIAN , PLETYUKHOV MIKHAIL , ZAITSEV OLEG
Published: March 2004

We summarize recent developments of the semiclassical description of shell effects in finite fermion systems with explicit inclusion of spin degrees of freedom, in particluar in the presence of spin-orbit interactions. We present a new approach that makes use of spin coherent states and a correspondingly enlarged classical phase space. Taking suitable limits, we can recover some of the earlier approaches. Applications to some model systems are presented.
STRUCTURE OF POLONIUM ISOTOPES AT HIGH SPIN WITH RFD + EUROBALL IV
Authors: ROSSÉ B. , STÉZOWSKI O. , MEYER M. , PRÉVOST A. , REDON N. , STYCZEŃ J. , BREKIESZ M. , GRȨBOSZ J. , MAJ A. , MȨCZYNSKI W. , PAWŁAT T. , ZIEBLIŃSKI M. , ZUBER K. , BEDNARCZYK P. , CURIEN D. , DORVAUX O. , GALL B. , PAPKA P. , ROBIN J. , VIVIEN J.P. , ASTIER A. , DELONCLE I. , PORQUET M.-G. , KEYES K. , PAPENBERG A. , SPOHR K.M. , HÜBEL H. , BRACCO A. , CAMERA F. , BASTIN J. , GORSKA M.
Published: March 2004

An experiment has been performed to investigate the structure at high spin of the neutron-deficient polonium isotopes using the Recoil Filter Detector coupled to the EUROBALL IV gamma array. High spin states of 200,201 Po have been populated by the 30 Si +176 Yb reaction at a beam energy of 160 MeV. We report here the performances of the RFD + EUROBALL IV coupling.
SHELL FORMATION AND THREE-BODY FORCES
Authors: ZUKER A. P.
Published: March 2004

The mechanism of shell formation will be explored, incorporating three-body forces, now known to be an indispensable part of the nuclear Hamiltonian.
MODELLING OF DISSIPATION IN NUCLEAR FISSION
Authors: SCHMITT C. , JURADO B. , JUNGHANS A. R. , SCHMIDT K.-H. , BENLLIURE J.
Published: March 2004

Peripheral heavy-ion collisions at relativistic energy are proposed as a new experimental approach dedicated to nuclear dissipation studies and, in particular, to investigate transient effects which are responsible for the inhibition of fission at the beginning of the process. To extract reliable information from the data, an analytical approximation of the time-dependent fission decay width is used in connection with new experimental signatures of relaxation effects.
THE ISOSCALAR COUPLING SCHEME IN NUCLEAR COLLECTIVE EXCITATIONS
Authors: ZAJAC KRYSTYNA
Published: March 2004

The influence of the proton–neutron pairing force on low–lying collective excitations of even nuclei is investigated within the interacting boson model containing isocsalar and isovector bosons. The application of the boson scheme shows that the deuteron–like pairs can be formed in the valence g–shell of a nucleus (both for protons and neutrons).
FISSION BARRIERS WITHIN THE LIQUID DROP MODEL WITH THE SURFACE-CURVATURE TERM
Authors: POMORSKI K. , DUDEK J.
Published: March 2004

The recently revised liquid drop model (PRC 67(2003) 044316) containing the curvature term reproduces the masses of 2766 experimentally known isotopes having Z≥8 and N≥8 with the r.m.s. deviation equal to 0.698 MeV when the microscopic corrections of Moeller et al. is used. The influence of the congruence energy as well as the compression term on the barrier heights is discussed within this new macroscopic model. The r.m.s. deviation of the fission barrier heights of 40 isotopes with Z≥34 is 1.73 MeV only when deformation-dependent congruence energy is included. The effect of the compression term in the liquid drop energy has rather weak influence on the barrier heights.
DESCRIPTION OF THE SUPERDEFORMED BAND OF 36Ar WITH THE GOGNY FORCE
Authors: RODRÍGUEZ-GUZMÁN R. R. , EGIDO J. L. , ROBLEDO L. M.
Published: March 2004

The superdeformed band of 36 Ar is studied with the Gogny force D1S and the angular momentum projected generator coordinate method for the quadrupole moment. The band head excitation energy, moments of inertia, B(E2) transition probabilities and stability against quadrupole fluctuations at low spin are studied. The Self Consistent Cranking method is also used to describe the superdeformed rotational band. In addition, properties of some normal deformed states are discussed.
SUPERFLUID LDA (SLDA): LOCAL DENSITY APPROXIMATION FOR SYSTEMS WITH SUPERFLUID CORRELATIONS
Authors: BULGAC AUREL , YU YONGLE
Published: March 2004

We present a concise account of our development of the first genuine Local Density Approximation (LDA) to the Energy Density Functional (EDF) for fermionic systems with superfluid correlations, with a particular emphasis to nuclear systems.
MICROSCOPIC STRUCTURE OF THE BIMODAL FISSION OF 258Fm
Authors: WARDA M. , POMORSKI K. , EGIDO J. L. , ROBLEDO L. M.
Published: March 2004

Constrained HFB calculations with the Gogny force are performed in order to investigate the bimodal fission of 258 Fm . The single-particle orbitals are analyzed in both fission modes. Density distributions of single nucleons show that the cores of the fragments are well separated far before the scission point.
SKYRME FORCES WITH EXTENDED DENSITY DEPENDENCE
Authors: COCHET B. , BENNACEUR K. , MEYER J. , BONCHE P. , DUGUET T.
Published: March 2004

A generalized parameterization of the Skyrme effective force is discussed. Preliminary results are presented for infinite symmetric and asymmetric nuclear matter. In particular, it is shown that an enlarged density dependence based on two terms allows to choose independently the incompressibility and the isoscalar effective mass.
SEMICLASSICAL ORIGIN OF SHELL STRUCTURES IN DEFORMED NUCLEI: DEPENDENCE ON SURFACE DIFFUSENESS AND EFFECT OF SPIN-ORBIT COUPLINGS
Authors: ARITA KEN-ICHIRO
Published: March 2004

Shell structures in nuclear mean field potentials are analyzed using semiclassical periodic-orbit theory. rα-type potential model is taken as an approximation of Woods-Saxon model, and spin-orbit coupling is also taken into account. Using this model, we examine shell structure as functions of deformation, nuclear size (diffuseness), and spin-orbit coupling strength. Significant roles of periodic orbit bifurcations for strong deformed shell effects are clarified. Special attentions will be paid to bifurcations of the 'bridge orbits', which emerge from symmetric orbits and then submerge in other symmetric orbits by varying a potential parameter.
NUCLEAR TETRAHEDRAL SYMMETRY
Authors: SCHUNCK NICOLAS , DUDEK JERZY
Published: March 2004

We recall the main features of the [Formula: see text] (tetrahedral) symmetry in atomic nuclei and present realistic mean-field calculations supporting the existence such a symmetry all over the nuclear chart. A few potential candidate-nuclei are investigated and the possible experimental signatures of the tetrahedral symmetry are also briefly discussed.
CURRENTS, SPIN DENSITIES AND MEAN-FIELD FORM FACTORS IN ROTATING NUCLEI: A SEMI-CLASSICAL APPROACH
Authors: BARTEL J. , BENCHEIKH K. , QUENTIN P.
Published: March 2004

We present self-consistent semi-classical local densities characterising the structure of rotating nuclei. A particular emphasis is put on those densities which are generated by the breaking of time-reversal symmetry through the cranking piece of the Routhian, namely the current density and the spin vector density. Our approach which is based on the Extended-Thomas-Fermi method goes beyond the Inglis cranking approach and contains naturally the Thouless-Valatin self-consistency terms expressing the response of the mean field to the time-odd part of the density matrix.
PAIRING CORRELATIONS IN THE STRONG FLUCTUATIONS REGIME
Authors: FERNÁNDEZ M. A. , EGIDO J. L.
Published: March 2004

A general BCS Ansatz based on the Generator Coordinate Method is proposed to study pairing properties in superconducting grains. The formalism is applied to the pairing Hamiltonian where we reproduce the exact solution in the weak, crossover and strong pairing regimes.
ANALYZING SHELL STRUCTURE FROM BABYLONIAN AND MODERN TIMES
Authors: BRACK-BERNSEN LIS , BRACK MATTHIAS
Published: March 2004

We investigate "shell structure" from Babylonian times: periodicities and beats in computer-simulated lunar data corresponding to those observed by Babylonian scribes some 2500 years ago. We discuss the mathematical similarity between the Babylonians' recently reconstructed method of determining one of the periods of the moon with modern Fourier analysis and the interpretation of shell structure in finite fermion systems (nuclei, metal clusters, quantum dots) in terms of classical closed or periodic orbits.
MEASURING CAPTURE CROSS SECTIONS FOR HEAVY-ELEMENT PRODUCTION
Authors: ROWLEY NEIL , GRAR NABILA
Published: March 2004

The creation of the nucleus of a superheavy element follows an extremely complex reaction path starting with the crossing of an external potential barrier (or distribution of barriers). This is followed by the evolution towards an equilibrated compound nucleus, which takes place in competition with pre-compound-nucleus fission (quasi-fission). Once formed the equilibrated compound nucleus must still survive against true fusion to yield a relatively long-lived evaporation residue. Much of this path is poorly understood, though recently, progress has been made on the role of the entrance-channel in quasi-fission. This will be briefly reported and a method proposed to measure the total capture cross section for such systems directly.
DYNAMICAL CALCULATION FOR FUSION-FISSION PROCESS IN SUPERHEAVY MASS REGION
Authors: ARITOMO Y. , OHTA M. , MATERNA T. , HANAPPE F. , STUTTGÉ L.
Published: March 2004

The fusion-fission process for the synthesis of superheavy elements is discussed on the basis of fluctuation-dissipation model. We employ three-dimensional Langevin equation. We investigate the fusion-fission process by analyzing not only the mass distribution of fission fragments but also neutron multiplicity on fusion-fission process.
SELFCONSISTENT FUSION BARRIERS AT NEAR BARRIER ENERGIES
Authors: SKALSKI JANUSZ
Published: March 2004

Fusion potentials are calculated for a number of reactions within the static Hartree-Fock method with the Skyrme force SkM*. Fusion barriers agree with the data considerably better than reaction Q values. This suggests some error cancellation, possibly with the relative kinetic energy term. Our results are consistent with the idea of fusion hindrance in tip collisions. Some comparison to results of the frozen density method is made.
MEAN-FIELD DESCRIPTION OF HEAVY-ION COLLISIONS
Authors: DOBROWOLSKI A. , POMORSKI K. , BARTEL J.
Published: March 2004

Using the collective potential between colliding ions based on the effective nucleon-nucleon interactions of the Skyrme type and the semi-classical Extended Thomas-Fermi approach we describe heavy-ion fusion cross sections applying a Monte-Carlo sampling method of trajectories with the Langevin formalism using friction as described in the so-called Surface-Friction Model.
FRAGMENT EXCITATION, KINETIC ENERGY DISTRIBUTIONS AND NEUTRON EVAPORATION IN NUCLEAR FISSION CALCULATED FROM A RANDOM EXCITATION MODEL
Authors: FAUST HERBERT R.
Published: March 2004

We present a model which allows for the calculation of fragment excitation energy, fragment kinetic energies and neutron evaporation in nuclear fission. The model is based on the assumption that, at the end of the fission process, fragments are excited to a temperature which is proportional to the reaction Q-value. Starting from this assumption the distribution functions of fragment excitation can be formulated and the distribution functions for the kinetic energies can be derived by a Monte Carlo method. From the distribution functions for the excitation energy neutron evaporation characteristics are calculated.
THERMAL SHAPE FLUCTUATIONS IN HOT NUCLEI
Authors: MARTIN V. , EGIDO J. L. , ROBLEDO L. M.
Published: March 2004

The behavior of several nuclear properties with temperature is analyzed within the framework of the Finite Temperature Hartree-Fock-Bogolyubov (FTHFB) theory with the Gogny force and large configuration spaces. As representative examples the nuclei 164 Er , 152 Dy , 192 Hg and 240 Pu are studied. Numerical results for the deformed to spherical shape phase transitions are presented. Thermal shape fluctuations in the quadrupole degree of freedom, around the mean field solution, are taken into account with the Landau prescription. We found a substantial effect of these fluctuations in the average value of several observables.
NUCLEAR PERIPHERY IN MEAN-FIELD MODELS
Authors: BARAN A. , MIERZYŃSKI P.
Published: March 2004

The halo factor is one of the experimental data which describes a distribution of neutrons in the nuclear periphery. In the presented paper we use Skyrme-Hartree (SH) and the Relativistic Mean Field (RMF) models to calculate the neutron excess factor ΔB which differs slightly from the halo factor f exp . The results of the calculations are compared to the measured data.
STATE DEPENDENT δ-PAIRING AND SPONTANEOUS FISSION
Authors: BARAN A. , ŁOJEWSKI Z. , SIEJA K.
Published: March 2004

We examine the fission barriers, mass parameters and spontaneous fission half lives of Fermium isotopes within the framework of the macroscopic-microscopic model with a δ-pairing interaction. Four different macroscopic models are applied and studied. The results are compared to experimental data and to the ones of the corresponding monopole pairing approach. The half lives obtained in the δ-pairing model are comparable with experimental data.
IMPORTANCE OF DEFORMATION AND ORIENTATION OF NUCLEAR SHAPES FOR THE SYNTHESIS OF SUPER-HEAVY ELEMENTS
Authors: KOWAL M. , ŁOJEWSKI Z.
Published: March 2004

We are studying the potential energy describing the entrance channel of a heavy-ion collisions for the axially symmetric deformed and arbitrarily oriented nuclear shapes. The paper presents an analysis of the influence of different orientations of the deformed ions on the height and shape of the fusion barrier. The net effect of the deformation degree of freedom on the transmission at sub-barrier energies is to enhance the fusion cross section. This problem is very important especially in the perspective of the synthesis of super-heavy elements.
IN-MEDIUM ION MASS RENORMALIZATION AND LATTICE VIBRATIONS IN THE NEUTRON STAR CRUST
Authors: MAGIERSKI PIOTR
Published: March 2004

The inner crust of a neutron star consists of nuclei immersed in a superfluid neutron liquid. As these nuclei move through the fermionic medium they bring it into motion as well. As a result their mass is strongly renormalized and the spectrum of the ion lattice vibrations is significantly affected. Consequently we predict that the specific heat and the lattice thermal energy of the Coulomb crystal at these densities are noticeably modified.
AN EXTENSION OF LAZY EVALUATION FOR INFLUENCE DIAGRAMS AVOIDING REDUNDANT VARIABLES IN THE POTENTIALS
Authors: VOMLELOVÁ MARTA , JENSEN FINN V.
Published: March 2004

Standard methods for solving influence diagrams consist in stepwise elimination of variables, and along with elimination of a variable a set of new potentials over new domains is calculated. It is well known that these methods tend to produce unnecessarily large domains resulting in excessive consumption of time and memory. The lazy evaluation method represents only a partial solution to the problem. In this paper we extend any potential with two graphs over its domain representing the dependencies of variables. When a node A is eliminated, all necessary structural information for establishing the minimal sets of domains for potentials is contained in these graphs. We push lazy evaluation a step further to avoid performing unnecessary multiplications and subsequent division with equivalent potentials.
PROBABILISTIC DECISION GRAPHS — COMBINING VERIFICATION AND AI TECHNIQUES FOR PROBABILISTIC INFERENCE
Authors: JAEGER MANFRED
Published: March 2004

We adopt probabilistic decision graphs developed in the field of automated verification as a tool for probabilistic model representation and inference. We show that probabilistic inference has linear time complexity in the size of the probabilistic decision graph, that the smallest probabilistic decision graph for a given distribution is at most as large as the smallest junction tree for the same distribution, and that in some cases it can in fact be much smaller. Behind these very promising features of probabilistic decision graphs lies the fact that they integrate into a single coherent framework a number of representational and algorithmic optimizations developed for Bayesian networks (use of hidden variables, context-specific independence, structured representation of conditional probability tables).
UNSUPERVISED LEARNING OF BAYESIAN NETWORKS VIA ESTIMATION OF DISTRIBUTION ALGORITHMS: AN APPLICATION TO GENE EXPRESSION DATA CLUSTERING
Authors: PEÑA J. M. , LOZANO J. A. , LARRAÑAGA P.
Published: March 2004

This paper proposes using estimation of distribution algorithms for unsupervised learning of Bayesian networks, directly as well as within the framework of the Bayesian structural EM algorithm. Both approaches are empirically evaluated in synthetic and real data. Specifically, the evaluation in real data consists in the application of this paper's proposals to gene expression data clustering, i.e., the identification of clusters of genes with similar expression profiles across samples, for the leukemia database. The validation of the clusters of genes that are identified suggests that these may be biologically meaningful.
ECONOMIC SELECTION OF MEAN VALUE FOR A FILLING PROCESS UNDER QUADRATIC QUALITY LOSS
Authors: LEE MIN-KOO , KIM SANG-BOO , KWON HYUCK-MOO , HONG SUNG HOON
Published: March 2004

Consider a filling process where containers are filled with an important ingredient in a character. All containers are inspected, and the containers satisfying to meet the predetermined specification limits are sold in a regular market for a fixed price, and failing to meet them are emptied and refilled by the same filling process after some reprocessing. We assume that reprocessing cost is proportional to the quantity of the ingredients in a container that is not changed after reprocessing.

An economic model is constructed on the basis of the selling price and the costs of production, inspection, reprocessing, and quality. We assume that the quality cost function is a quadratic function of the deviation from target and the quantity of the ingredients in a container is normally distributed with a known variance. Method for finding the optimum process mean is presented and a numerical example is given.
POSTBUCKLING BEHAVIOR OF BEAMS ON TWO-PARAMETER ELASTIC FOUNDATION
Authors: NGUYEN DINH KIEN
Published: March 2004

The postbuckling behavior of beams on a two-parameter elastic foundation subjected to axial forces is investigated. Based on the strain energy expression, a two-node nonlinear beam element is formulated. The element includes the effects of shear deformation, foundation deflection in both the horizontal and vertical directions. The bracketing procedure and the iterative Newton–Raphson method with arc-length control technique are adopted to compute the critical loads and equilibrium paths of the beams with various boundary conditions. The numerical results show that the critical load and the postbuckling behavior are not only governed by the foundation stiffness, but by the foundation deflection in the horizontal direction also. The postbuckling characteristics of the beams are altered by ignoring the foundation deflection in the horizontal direction. A detail investigation is carried out to highlight the influences of the partial support by the foundation and the beam slenderness on the critical load and the postbuckling behavior.
A CO-ROTATION BASED SECANT MATRIX PROCEDURE FOR ELASTIC POSTBUCKLING ANALYSIS OF TRUSS STRUCTURES
Authors: JAYACHANDRAN S. ARUL , KALYANARAMAN V. , NARAYANAN R.
Published: March 2004

To investigate the geometrically nonlinear behavior of space structures using finite elements, the total Lagrangian (TL), updated Lagrangian (UL) and co-rotational (CR) procedures have been used by researchers. For 3D truss structures, the CR formulation has been reported to be computationally more efficient as it possesses the rigid body displacement components during deformations. In this paper, the secant stiffness matrix of truss element will be derived using a simple co-rotational, total Lagrangian (CR–TL) formulation. The incremental rotation matrix, which is the pivotal quantity in the CR formulation, is derived from geometric principles. The secant stiffness matrix is presented in terms of the natural degrees-of-freedom of the truss element. The efficiency and reliability of the present formulation is demonstrated in the solution of several truss problems involving the postbuckling behavior.
SHEAR BUCKLING OF CORRUGATED PLATES WITH EDGES ELASTICALLY RESTRAINED AGAINST ROTATION
Authors: MACHIMDAMRONG CHAWALIT , WATANABE EIICHI , UTSUNOMIYA TOMOAKI
Published: March 2004

This paper presents an estimation of the elastic shear buckling capacity of corrugated plates with edges elastically restrained against rotation. The corrugated plate possesses higher shear buckling capacity compared to an unfolded flat plate. It has been used to replace the concrete web in PC box girders in recent bridge constructions in Japan. In this study, the corrugated plate is modelled as an orthotropic Mindlin plate. Elastically rotational restraint on boundary edges is taken into account in the form of rotational springs in the analysis. The prediction of buckling capacities of corrugated plates is carried out by using the Rayleigh–Ritz method, which was proved to be consistent with those as predicted by existing formulas for the limiting cases of simply-supported and clamped edges. The present study covers the more general case of elastically rotational restraint on the boundary edges showing transition curve of plate buckling capacities from the case of simple support to the case of clamped support.
INELASTIC REPETITIVE SHEAR AND FLEXURAL BUCKLING OF PLATE GIRDERS
Authors: TAKEDA HACHIRO , WATANABE EIICHI , KUNISHI RYO
Published: March 2004

In the Great Hanshin–Awaji earthquake of 1995, the phenomena of repetitive inelastic buckling were observed in many steel girders including horizontal girders of portal steel piers on elevated highways. The authors have been interested in the ability of steel girders to dissipate the hysteretic plastic strain energy due to such repetitive buckling of steel girders for earthquake-resistance design. This paper is focused on the repetitive buckling behavior of eight steel plate girders under inelastic shear or the combined shear and bending due to a concentrated point load adopting two independent cyclic loading patterns. The model girders were selected considering the combined variations of flange thickness, flange width and depth-to-thickness ratio of the web. Good correlations were found between the results of tests and finite element analyses using shell elements considering the material and geometrical nonlinearities in the repetitive inelastic buckling behavior of plate girders.