bluuebunny/crossref_metadata_2025 huggingface dataset:
Symptoms of musculoskeletal disorders in stage rally drivers and co-drivers
Authors: Mansfield N J , Marshall J M
Published: July 2002

Background—During stage rallying, musculoskeletal injuries may be provoked by the high magnitude of vibration and shock to which the driver and co-driver are exposed. Drivers and co-drivers experience similar exposure to whole body mechanical shocks and vibration but different exposure to hand/wrist stressors.

Objectives—To investigate by a questionnaire study the prevalence of symptoms of musculoskeletal injuries after rallying in 13 professional and 105 amateur stage rally competitors.

Methods—The self administered questionnaire investigated whole body and hand/wrist symptoms of musculoskeletal injury. It was loosely based on the Nordic design.

Results—91% of participants who competed or tested for more than 10 days a year (n=90) reported discomfort in at least one body area after rallying. Problems in the lumbar spine (70%), cervical spine (54%), shoulders (47%), and thoracic spine (36%) were the most common. There was a higher prevalence of cervical spine discomfort for co-drivers (62%) than for drivers (46%). Conversely, there was higher prevalence of discomfort in the hands and wrists for drivers (32%) than co-drivers (9%). The prevalence of low back pain in rally participants is higher than that generally reported for workers exposed to whole body vibration. The prevalence of discomfort in the hand and wrist for rally drivers is similar to that previously reported for Formula 1 drivers.

Conclusions—Most stage rally drivers and co-drivers report symptoms of musculoskeletal injury. It is logical to relate the high prevalence of symptoms of injury to the extreme environment of the rally car.
Acid regulates inflammatory response in a rat model of induction of gastric ulcer recurrence by interleukin 1β
Authors: Watanabe T , Higuchi K , Tominaga K , Fujiwara Y , Arakawa T
Published: July 2002

BACKGROUND

In a previous study we showed that interleukin 1β (IL-1β) caused recurrence of gastric ulcers in rats, and that adhesion molecules (intercellular adhesion molecule 1 and leucocytic β2 integrins) play a role in this recurrence. Although gastric acid plays an important role in many types of gastric injuries, including peptic ulcer recurrence, the mechanism(s) remains unclear.

AIMS

To examine the involvement of gastric acid in induction of ulcer recurrence by IL-1β, and to investigate the role of gastric acid in inflammatory responses during ulcer recurrence.

METHODS

Rats with healed ulcers were used. Rats were given 1 μg/kg IL-1β intraperitoneally. Another group of rats was given 20 mg/kg omeprazole for three days to inhibit acid secretion, and received IL-1β 20 hours after the first administration of omeprazole. They were then given 0.15 N HCl or vehicle at 0, 12, 24, and 36 hours after IL-1β treatment. Some rats were given acid alone at the same time points. Expression of adhesion molecules was examined immunohistochemically and concentrations of IL-1β and tumour necrosis factor α (TNF-α) were measured by ELISA in scar tissue 24 hours after IL-1β treatment.

RESULTS

IL-1β increased expression of adhesion molecules and concentrations of IL-1β and TNF-α in scar tissue by 24 hours after IL-1β treatment, and nine of 11 healed ulcers had recurred by 48 hours. Omeprazole inhibited the effects of IL-1β. HCl acid abolished the inhibitory effects of omeprazole. Acid alone affected neither expression of adhesion molecules nor cytokine concentrations, and did not cause recurrence.

CONCLUSIONS

Gastric acid is required for recurrence of gastric ulcers caused by IL-1β, and gastric acid stimulates the inflammatory process in scarred mucosa during ulcer recurrence.
Acute vascular responses to the frequency of vibration transmitted to the hand
Authors: Bovenzi Massimo , Lindsell Christopher J , Griffin Michael J
Published: July 2002

OBJECTIVES

To investigate the acute effects of the frequency of hand transmitted vibration on finger circulation. A further aim was to investigate whether the frequency weighting assumed in current standards for hand transmitted vibration reflects the haemodynamic changes which occur in the fingers exposed to vibration with different frequencies but with the same frequency weighted acceleration magnitude.

METHODS

Finger skin temperature (FST) and finger blood flow (FBF) were measured in the middle fingers of both hands of 10 healthy men. With a static load of 10 N, the right hand was exposed for 15 minutes to the following root mean square (rms) acceleration magnitudes and frequencies of vertical vibration: 5.5 m/s2at 16 Hz; 11 m/s2at 31.5 Hz; 22 m/s2at 63 Hz; 44 m/s2at 125 Hz; and 88 m/s2at 250 Hz. These exposures to vibration produce the same frequency weighted acceleration magnitude (5.5 m/s2rms) according to the frequency weighting included in the international standard ISO 5349. A control condition consisted of exposure to the static load only. Finger circulation was measured before application of the vibration and static load and at fixed intervals during exposure to vibration and a 45 minute recovery period.

RESULTS

No significant changes in finger circulation were found with only the static load. The FST did not change significantly during or after acute exposure to vibration. In the vibrated right finger, exposures to vibration with frequencies of 31.5–250 Hz provoked a greater reduction in FBF than did vibration of 16 Hz or the static load only. In the non-vibrated left finger, the FBF measured with vibration at each frequency of 63–250 Hz was significantly lower than that measured with static load only. The reduction in FBF during exposure to vibration with any frequency was stronger in the vibrated finger than in the non-vibrated finger. In both fingers, there was a progressive decrease in FBF after the end of exposure to vibration with frequencies of 31.5–250 Hz. The higher the frequency of vibration, the stronger the decrease in FBF in both fingers during recovery.

CONCLUSIONS

Acute exposures to vibration with equal frequency weighted magnitude reduce the FBF in both vibrated and non-vibrated fingers for frequencies between 31.5 and 250 Hz. The extent of digital vasoconstriction after exposure to vibration increases with increasing frequency. The frequency weighting given in current standards tends to overestimate the vasoconstriction associated with acute exposures to vibration frequencies around 16 Hz.
Experimental exposure to propylene glycol mist in aviation emergency training: acute ocular and respiratory effects
Authors: Wieslander G , Norbäck D , Lindgren T
Published: July 2002

OBJECTIVES

Propylene glycol (PG) (1–2 propanediol; CAS No 57–55–6) is a low toxicity compound widely used as a food additive, in pharmaceutical preparations, in cosmetics, and in the workplace—for example, water based paints, de-icing fluids, and cooling liquids. Exposure to PG mist may occur from smoke generators in discotheques, theatres, and aviation emergency training. Propylene glycol may cause contact allergy, but there is sparse information on health effects from occupational exposure to PG.

METHODS

Non-asthmatic volunteers (n=27) were exposed in an aircraft simulator to PG mist over 1 minute, during realistic training conditions. Geometric mean concentration of PG was 309 mg/m3(range 176–851 mg/m3), with the highest concentrations in the afternoon. The medical investigation was performed both before and after the exposure (within 15 minutes). It included an estimate of tear film stability break up time, nasal patency by acoustic rhinometry, dynamic spirometry, and a doctor's administered questionnaire on symptoms.

RESULTS

After exposure to PG mist for 1 minute tear film stability decreased, ocular and throat symptoms increased, forced expiratory volume in 1 second/forced vital capacity (FEV1/FVC) was slightly reduced, and self rated severity of dyspnoea was slightly increased. No effect was found for nasal patency, vital capacity (VC), FVC, nasal symptoms, dermal symptoms, smell of solvent, or any systemic symptoms. Those exposed to the higher concentrations in the afternoon had a more pronounced increase of throat symptoms, and a more pronounced decrease of tear film stability. In four subjects who reported development of irritative cough during exposure to PG, FEV1was decreased by 5%, but FEV1was unchanged among those who did not develop a cough. Those who developed a cough also had an increased perception of mild dyspnoea.

CONCLUSION

Short exposure to PG mist from artificial smoke generators may cause acute ocular and upper airway irritation in non-asthmatic subjects. A few may also react with cough and slight airway obstruction.
The role of cumulative physical work load in lumbar spine disease: risk factors for lumbar osteochondrosis and spondylosis associated with chronic complaints
Authors: Seidler A , Bolm-Audorff U , Heiskel H , Henkel N , Roth-Küver B , Kaiser U , Bickeböller R , Willingstorfer W J , Beck W , Elsner G
Published: July 2002

OBJECTIVES

To investigate the relation with a case-control study between symptomatic osteochondrosis or spondylosis of the lumbar spine and cumulative occupational exposure to lifting or carrying and to working postures with extreme forward bending.

METHODS

From two practices and four clinics were recruited 229 male patients with radiographically confirmed osteochondrosis or spondylosis of the lumbar spine associated with chronic complaints. Of these 135 had additionally had acute lumbar disc herniation. A total of 197 control subjects was recruited: 107 subjects with anamnestic exclusion of lumbar spine disease were drawn as a random population control group and 90 patients admitted to hospital for urolithiasis who had no osteochondrosis or spondylosis of the lumbar spine radiographically were recruited as a hospital based control group. Data were gathered in a structured personal interview and analysed using logistic regression to control for age, region, nationality, and other diseases affecting the lumbar spine. To calculate cumulative forces to the lumbar spine over the entire working life, the Mainz-Dortmund dose model (MDD), which is based on an overproportional weighting of the lumbar disc compression force relative to the respective duration of the lifting process was applied with modifications: any objects weighing ⩾5 kg were included in the calculation and no minimum daily exposure limits were established. Calculation of forces to the lumbar spine was based on self reported estimates of occupational lifting, trunk flexion, and duration.

RESULTS

For a lumbar spine dose >9×106Nh (Newton×hours), the risk of having radiographically confirmed osteochondrosis or spondylosis of the lumbar spine as measured by the odds ratio (OR) was 8.5 (95% confidence interval (95% CI) 4.1 to 17.5) compared with subjects with a load of 0 Nh. To avoid differential bias, forces to the lumbar spine were also calculated on the basis of an internal job exposure matrix based on the control subjects' exposure assessments for their respective job groups. Although ORs were lower with this approach, they remained significant.

CONCLUSIONS

The calculation of the sum of forces to the lumbar spine is a useful tool for risk assessment for symptomatic osteochondrosis or spondylosis of the lumbar spine. The results suggest that cumulative occupational exposure to lifting or carrying and extreme forward bending increases the risk for developing symptomatic osteochondrosis or spondylosis of the lumbar spine.
Is there an association between shift work and having a metabolic syndrome? Results from a population based study of 27 485 people
Authors: Karlsson B , Knutsson A , Lindahl B
Published: July 2002

OBJECTIVES

To explore how metabolic risk factors for cardiovascular disease (CVD) differ between shift workers and day workers in a defined population. Shift work has been associated with an increased risk of CVD. Risk factors and causal pathways for this association are only partly known.

METHODS

A working population of 27 485 people from the Västerbotten intervention program (VIP) has been analysed. Cross sectional data, including blood sampling and questionnaires were collected in a health survey.

RESULTS

Obesity was more prevalent among shift workers in all age strata of women, but only in two out of four age groups in men. Increased triglycerides (>1.7 mmol/l) were more common among two age groups of shift working women but not among men. Low concentrations of high density lipoprotein (HDL) cholesterol (men<0.9 and women<1.0 mmol/l) were present in the youngest age group of shift workers in both men and women. Impaired glucose tolerance was more often found among 60 year old women shift workers. Obesity and high triglycerides persisted as risk factors in shift working men and women after adjusting for age and socioeconomic factors, with an OR of 1.4 for obesity and 1.1 for high triglyceride concentrations. The relative risks for women working shifts versus days with one, two, and three metabolic variables were 1.06, 1.20, and 1.71, respectively. The corresponding relative risks for men were 0.99, 1.30, and 1.63, respectively.

CONCLUSIONS

In this study, obesity, high triglycerides, and low concentrations of HDL cholesterol seem to cluster together more often in shift workers than in day workers, which might indicate an association between shift work and the metabolic syndrome.
Pulmonary arteriovenous malformation
Authors: Khurshid I , Downie G H
Published: July 2002

Pulmonary arteriovenous malformations (PAVM) are rare pulmonary vascular anomalies. Although most patients are asymptomatic, PAVMs can cause dyspnoea from right-to-left shunt. Because of paradoxical emboli, various central nervous system complications have been described including stroke and brain abscess. There is a strong association between PAVM and hereditary haemorrhagic telangiectasia. Chest radiography and contrast enhanced computed tomography are essential initial diagnostic tools but pulmonary angiography is the gold standard. Contrast echocardiography is useful for diagnosis and monitoring after treatment. Most patients should be treated. Therapeutic options include angiographic embolisation with metal coil or balloon occlusion and surgical excision.
Inputs and outputs of mercury from terrestrial watersheds: a review
Authors: Grigal D F
Published: July 2002

This review focuses on mercury (Hg) inputs and outputs in temperate and boreal terrestrial systems. It covers deposition via throughfall and litterfall, whose sum (ca. 38 µg m2 a1) is greater than that via precipitation (ca. 10 µg m2 a1). Outputs considered include volatilization, soil sequestration, and streamflow. The former is highly uncertain, but the mean rate (11 ng m2 h1) over a growing season is equivalent to about 32 µg m2 a1. Modern rates of soil sequestration (ca. 5 µg m2 a1) and streamflow fluxes (ca. 2 µg m2 a1) balance the annual budget. The majority of the uncertainty in the budget is related to volatilization. Nonetheless, a large fraction of atmospheric Hg is likely a product of continuing deposition and volatilization. Watershed characteristics related to streamflow fluxes of both Hg and methylmercury (MeHg) are discussed. Both runoff concentration and flux of Hg are weakly and inversely related to watershed size. Dissolved organic carbon (DOC) and particulates are important carriers of Hg; watershed activities that affect either affect Hg flux. Runoff flux of MeHg is skewed with about 80% of observations less than 0.15 µg m2 a1. Although there is no pattern of MeHg flux with watershed size, there is a strong positive relationship between flux and wetland area. Wetlands are a site of MeHg production and their presence increases water residence time; both increase MeHg flux. Concentrations of MeHg in streamflow from watersheds with wetlands are near the current water quality criterion, and effective control measures in those watersheds appear problematic.Key words: deposition, non-point pollution, methylmercury, wetlands, dissolved organic carbon (DOC).
The Early Permian floras of Prince Edward Island, Canada: differentiating global from local effects of climate change
Authors: Ziegler Alfred M , Rees Peter McA , Naugolnykh Serge V
Published: July 2002

New Permian plant specimens are described from Prince Edward Island, Canada. They include attached specimens of leaf and stem genera Walchia and Tylodendron, enabling reconstruction of this Early Permian conifer. Although poorly preserved, the study of these floras extends our knowledge of diversity and climate conditions in the region. By placing these findings in a broader stratigraphic and geographic framework, we can document the phytogeographic and climate trends through the Carboniferous and Permian in the Maritimes Basin. Combined data on temporal trends in climate-sensitive sediments, as well as macrofloral and microfloral diversities, generally match the independently derived paleolatitudinal estimates. These show the region migrating from the southern subtropics across the Equator and into the northern subtropics between the Early Carboniferous and Early Permian. Evaporites and pedogenic carbonates, together with low-diversity floras, match its subtropical position in the Early Carboniferous. In contrast, coals are present in the Late Carboniferous, accompanied by high-diversity macro- and microfloral remains, when the region was on or near the Equator. However, the subsequent transition to pedogenic carbonates, eolian sands, and lower diversity floras is not matched by significant poleward latitudinal motion. We ascribe these changes to a decrease in moisture availability, as transgressions of epeiric seas became less frequent and finally stopped altogether, causing an increase of continentality in Euramerica.
Evolution of Precambrian continental lithosphere in Western Canada: results from Lithoprobe studies in Alberta and beyond
Authors: Ross Gerald M
Published: July 2002

The Precambrian lithosphere of western Canada was assembled into the present crustal configuration between ca. 2.01.78 Ga by plate collisions, sometimes accompanied by arc magmatism, with subsequent cooling of the lithosphere since ca. 1.7 Ga. Collisional processes inferred along preserved plate sutures include (1) subduction of oceanic lithosphere and accretion of Proterozoic arc crust to the western Rae Province; (2) marginal basin consumption and tectonic entrapment of the Hearne Province between coeval subductioncollision zones; and (3) amagmatic marginal basin closure, perhaps analogous to the roots of small collisional orogens, such as the Pyrenees. Seismic reflection profiles acquired during the Lithoprobe Alberta Basement Transect have captured images of syn- to post-collisional structures along these sutures and evidence for crustal-scale thrust imbrication and rigid body accretion of Archean crust with preservation of precollisional tectonic fabric. The degree to which lithospheric mantle beneath Archean crustal blocks was preserved during these collisions is unknown, although tectonic geometries imply significant thermal and (or) mechanical interaction. Post-collisional, intrusive mafic magmatism is imaged widely in both seismic reflection and refraction surveys. These magmatic events are demonstrably Proterozoic, based on crosscutting relationships seen on seismic reflection profiles and geochronology of lower crustal xenoliths, and are comparable in scale to Phanerozoic igneous provinces (e.g., large igneous provinces) but have little preserved surface manifestation. Reactivation of Precambrian basement structures is limited or very subtle, reflecting strength control by the mantle on stress transmission and crustal failure. Long-wavelength elastic deformation of the crust during the Phanerozoic occurred in regions associated with, or adjacent to, Proterozoic mafic magmatism, suggesting local rheologic control of anomalous Phanerozoic paleotopography.
SYMMETRIES AND QUANTIZATION: STRUCTURE OF THE STATE SPACE
Authors: DIVAKARAN P. P.
Published: July 2002

This paper is concerned with the relationship between the group G of all symmetries of an unconstrained dynamical system and the space of its quantum states. The chief aim is to establish the validity of the claim that "quantizing a system" means deciding what G is and determining all projective unitary representations of G. The mathematical tool suited to this purpose is the theory of central extensions of an arbitrary group G by the circle group T (and the closely related cohomology group H2 (G, T)). The fundamental structural property is that there is a universal state space [Formula: see text] embedding all states, a unitary representation space of the universal central extension [Formula: see text] of G, on which the Pontryagin dual H2 (G, T)⋆ of H2 (G, T) operates as a group of su-perselection rules, so that the superselection sectors are [Formula: see text] and observables are self-adjoint operators Vh → Vh. This leads to a classification of time-evolution operators respecting the symmetries by H2 (G, T) and a general understanding of "anomalies" as arising from a mismatch of sectors to which symmetry transformations and time-evolution refer. For the special case of a Lie group G of symmetries, [Formula: see text] of G coincides with [Formula: see text] the universal covering group, if G is semisimple. More generally, depending on whether or not G is semisimple and/or simply connected, inequivalent quantizations are of topological, algebraic or "mixed" origin; in the algebraic case, the relationship between anomalous conservation laws and invariant dynamics is explicitly given. Illustrative examples worked out include the Euclidean group E (d) and the (connected) Poincaré group P (d, 1) for arbitrary spatial dimension d and the discrete groups (Z/N)2 and Z2 appropriate for planar square crystals — in particular, the absence of "fractional" angular momentum in the plane is established and the difficulties specific to (2,1)-dimensional quantum field theories precisely formulated. The paper concludes by noting that a number of ambiguities generally supposed to affect traditional procedures of quantization resolve themselves satisfactorily in this approach.

Mathematically, the paper is self-contained as far as the concepts and results are concerned; occasionally, proofs of well-known facts are reworked when they serve to illustrate the value of the symmetry point of view. The theory of universal central extensions of groups, including important special cases, is treated in detail in an appendix by M. S. Raghunathan, in view of its significance for quantization and the absence of a similar account in the literature.
APPLICATIONS AND SEXUAL VERSION OF A SIMPLE MODEL FOR BIOLOGICAL AGING
Authors: SOUSA A. O. , DE OLIVEIRA S. MOSS , STAUFFER D.
Published: July 2002

We use a simple model for biological aging to study the mortality of the population, obtaining a good agreement with the Gompertz law. We also simulate the same model on a square lattice, considering different strategies of parental care. The results are in agreement with those obtained earlier with the more complicated Penna model for biological aging. Finally, we present the sexual version of this simple model.
Tc ENHANCEMENT IN La2-xSrxCuO4 BY ANISOTROPIC PRESSURE
Authors: Fujita T. , Hori J. , Goko T. , Nakamura F.
Published: July 2002

Pressure dependence of superconducting transition temperature Tc was investigated up to 8 GPa using high-quality single-crystals of La 2-x Sr x CuO 4. Variation of Tc was found to be very sensitive to the deviation from hydrostaticity as well as to the fine structure of the lattice including the tilting of the CuO 6 octahedra or the buckling of the CuO 2 planes. Compression along the c axis contributes most negatively to superconductivity. From the effect of nonhydrostatic pressure, we succeeded in estimating the potential value of Tc at ambient pressure in the tetragonal phase, which was found to be much higher than in the orthorhombic phase. Utilizing anisotropic strains induced by nonhydrostatic pressure, furthermore, we controlled the lattice and achieved the highest Tc of 51.6 K ever reported for La-214.
SIGN LANGUAGE RECOGNITION BASED ON HMM/ANN/DP
Authors: GAO WEN , MA JIYONG , WU JIANGQIN , WANG CHUNLI
Published: July 2002

In this paper, a system designed for helping the deaf to communicate with others is presented. Some useful new ideas are proposed in design and implementation. An algorithm based on geometrical analysis for the purpose of extracting invariant feature to signer position is presented. An ANN–DP combined approach is employed for segmenting subwords automatically from the data stream of sign signals. To tackle the epenthesis movement problem, a DP-based method has been used to obtain the context-dependent models. Some techniques for system implementation are also given, including fast matching, frame prediction and search algorithms. The implemented system is able to recognize continuous large vocabulary Chinese Sign Language. Experiments show that proposed techniques in this paper are efficient on either recognition speed or recognition performance.
ITERATED FUNCTION SYSTEMS FOR OBJECT GENERATION AND RENDERING
Authors: JONES HUW
Published: July 2002

Iterated function systems (IFS) have been used since the mid 1980s in generating fractal forms and in image compression. They have the property of encoding complex structures as relatively simple and concise algorithms and data sets. The complete information for generation of an IFS structure, known as an "attractor", is held in the definition of a few transformation functions, typically affine transformations described by simple linear equations. These transform 2D or 3D objects by combinations of translation, scaling and rotation, preserving parallel lines. The process of generating an attractor using either of the two standard methods is straightforward, but the inverse problem of identifying the IFS for a particular attractor is more difficult. The paper introduces and reviews the uses of Iterated Function Systems, particularly for 2D image and 3D object generation. As well as a general exposition of the method, results developed by the author for creation of fractal objects are shown. Some are based on regular geometric structures, others mimic a number of naturally occurring forms. These deviate from normal practice in using nonaffine transformations in the IFS definition. A new method for synthesising images of smooth objects using IFS is developed and illustrated as an alternative to standard 3D rendering methods (see the cover picture), which are briefly described.
IMPROVED NUMERICAL FLOQUET MULTIPLIERS
Authors: LUST KURT
Published: July 2002

This paper studies numerical methods for linear stability analysis of periodic solutions in codes for bifurcation analysis of small systems of ordinary differential equations (ODEs). Popular techniques in use today (including the AUTO97 method) produce very inaccurate Floquet multipliers if the system has very large or small multipliers. These codes compute the monodromy matrix explicitly or as a matrix pencil of two matrices. The monodromy matrix arises naturally as a product of many matrices in many numerical methods, but this is not exploited. In this case, all Floquet multipliers can be computed with very high precision by using the periodic Schur decomposition and corresponding algorithm [Bojanczyk et al., 1992]. The time discretisation of the periodic orbit becomes the limiting factor for the accuracy. We present just enough of the numerical methods to show how the Floquet multipliers are currently computed and how the periodic Schur decomposition can be fitted into existing codes but omit all details. However, we show extensive test results for a few artificial matrices and for two four-dimensional systems with some very large and very small Floquet multipliers to illustrate the problems experienced by current techniques and the better results obtained using the periodic Schur decomposition. We use a modified version of AUTO97 [Doedel et al., 1997] in our experiments.
A NEW CHAOTIC ATTRACTOR COINED
Authors: LÜ JINHU , CHEN GUANRONG
Published: July 2002

This letter reports the finding of a new chaotic attractor in a simple three-dimensional autonomous system, which connects the Lorenz attractor and Chen's attractor and represents the transition from one to the other.
DYNAMICAL ANALYSIS OF A NEW CHAOTIC ATTRACTOR
Authors: LÜ JINHU , CHEN GUANRONG , ZHANG SUOCHUN
Published: July 2002

Dynamical behaviors of a new chaotic attractor is investigated in this paper. Some basic properties, bifurcations, routes to chaos, and periodic windows of the new system are studied either analytically or numerically. Meanwhile, the transition between the Lorenz attractor and Chen's attractor through the new system is explored.
CURRENT TREATMENT OF GANGLION OF THE WRIST
Authors: Ho P. C. , Griffiths J. , Lo W. N. , Yen C. H. , Hung L. K.
Published: July 2002

Ganglion of the wrist is one of the the most common lesions of the hand. The cause of pain in an occult dorsal wrist ganglion has been linked to compression of the posterior interosseous nerve at the wrist. A case is presented in this paper and the pathoanatomy discussed. Ultrasound-guided aspiration after hyaluronidase instillation provided a useful alternative to surgery with a high success rate. Arthroscopic decompression for dorsal and palmar wrist ganglia offered the patient the benefit of smaller surgical scars and a high success rate. A description of the surgical techniques, pathoanatomy, and early results of the authors and a review of the literature is presented.
THE END-OF-THE-YEAR BONUS: HOW TO OPTIMALLY REWARD A TRADER?
Authors: AHN H. , DEWYNNE JEFF , HUA P. , PENAUD ANTONY , WILMOTT PAUL
Published: July 2002

Traders are compensated by bonuses, in addition to their basic salary. However, little is known about how to optimally reward a trader. In this article we build a framework for the study of this problem and explore a variety of possible compensation structures.
Refinement methods for geometric bounds in constructive solid geometry
Authors: Cameron Stephen , Yap Chee-Keng
Published: July 2002

In constructive solid geometry, geometric solids are represented as trees whose leaves are labeled by primitive solids and whose internal nodes are labeled by set-theoretic operations. A
bounding function
in this context is an upper or lower estimate on the extent of the constituent sets; such bounds are commonly used to speed up algorithms based on such trees. We introduce the class of
totally consistent bounding functions
, which have the desirable properties of allowing surprisingly good bounds to be built quickly. Both outer and inner bounds can be refined using a set of rewrite rules, for which we give some complexity and convergence results. We have implemented the refinement rules for outer bounds within a solid modeling system, where they have proved especially useful for intersection testing in three and four dimensions. Our implementations have used boxes as bounds, but different classes (shapes) of bounds are also explored. The rewrite rules are also applicable to relatively slow, exact operations, which we explore for their theoretical insight, and to general Boolean algebras. Results concerning the relationship between these bounds and active zones are also noted.
Functional dependencies in Horn clause queries
Authors: Mendelzon Alberto O. , Wood Peter T.
Published: July 2002

When a database query is expressed as a set of Horn clauses whose execution is by top-down resolution of goals, there is a need to improve the backtracking behavior of the interpreter. Rather than putting on the programmer the onus of using extra-logical operators such as
cut
to improve performance, we show that some uses of the cut can be automated by inferring them from functional dependencies. This requires some knowledge of which variables are guaranteed to be bound at query execution time; we give a method for deriving such information using data flow analysis.
A distributed object-oriented database system supporting shared and private databases
Authors: Kim Won , Ballou Nat , Garza Jorge F. , Woelk Darrell
Published: July 2002

ORION-2 is a commercially available, federated, object-oriented database management system designed and implemented at MCC. One major architectural innovation in ORION-2 is the coexistence of a shared databese and a number of private databases. The shared database is accessible to all authorized users of the system, while each private database is accessible to only the user who owns it. A distributed database system with a shared database and private databases for individual users is a natural architecture for data-intensive application environments on a network of workstations, notably computer-aided design and engineering systems. This paper discusses the benefits and limitations of such a system and explores the impact of such an architecture on the semantics and implementation of some of the key functions of a database system, notably queries, database schema, and versions. Although the issues are discussed in the context of an object-oriented data model, the results (at least significant portions thereof) are applicable to database systems supporting other data models.
The design and implementation of hierarchical software systems with reusable components
Authors: Batory Don , O'Malley Sean
Published: July 2002

We present a domain-independent model of hierarchical software system design and construction that is based on interchangeable software components and large-scale reuse. The model unifies the conceptualizations of two independent projects, Genesis and Avoca, that are successful examples of software component/building-block technologies and domain modeling. Building-block technologies exploit large-scale reuse, rely on open architecture software, and elevate the granularity of programming to the subsystem level. Domain modeling formalizes the similarities and differences among systems of a domain. We believe our model is a blueprint for achieving software component technologies in many domains.
Undecidability of static analysis
Authors: Landi William
Published: July 2002

Static analysis of programs is indispensable to any software tool, environment, or system that requires compile-time information about the semantics of programs. With the emergence of languages like C and LISP, static analysis of programs with dynamic storage and recursive data structures has become a field of active research. Such analysis is difficult, and the static-analysis community has recognized the need for simplifying assumptions and approximate solutions. However, even under the common simplifying assumptions, such analyses are harder than previously recognized. Two fundamental static-analysis problems are
may alias
and
must alias
. The former is not recursive (is undecidable), and the latter is not recursively enumerable (is uncomputable), even when all paths are executable in the program being analyzed for languages with if statements, loops, dynamic storage, and recursive data structures.
Cognitive bias in software engineering
Authors: Stacy Webb , MacMillan Jean
Published: July 2002

Developer's thought processes are a fundamental area of concern. Cognitive scientist have discovered that people's intiative inferences and probality judgments do not strictly conform to the laws of logic or mathematics, and that people are willing to provide plausible explanations for random events. This article examines the role these phenomena might have in software development, ultimately concluding that what are cast as one-sided software development guidelines often can be recast beneficially as two-sided trade-offs.
Temporal difference learning and TD-Gammon
Authors: Tesauro Gerald
Published: July 2002

Ever since the days of Shannon's proposal for a chess-playing algorithm [12] and Samuel's checkers-learning program [10] the domain of complex board games such as Go, chess, checkers, Othello, and backgammon has been widely regarded as an ideal testing ground for exploring a variety of concepts and approaches in artificial intelligence and machine learning. Such board games offer the challenge of tremendous complexity and sophistication required to play at expert level. At the same time, the problem inputs and performance measures are clear-cut and well defined, and the game environment is readily automated in that it is easy to simulate the board, the rules of legal play, and the rules regarding when the game is over and determining the outcome.
Modification of the minimum-degree algorithm by multiple elimination
Authors: Liu Joseph W. H.
Published: July 2002

The most widely used ordering scheme to reduce fills and operations in sparse matrix computation is the minimum-degree algorithm. The notion of
multiple elimination
is introduced here as a modification to the conventional scheme. The motivation is discussed using the
k
-by-
k
grid model problem. Experimental results indicate that the modified version retains the fill-reducing property of (and is often better than) the original ordering algorithm and yet requires less computer time. The reduction in ordering time is problem dependent, and for some problems the modified algorithm can run a few times faster than existing implementations of the minimum-degree algorithm. The use of
external degree
in the algorithm is also introduced.
Artificial life meets entertainment
Authors: Maes Pattie
Published: July 2002

The relatively new field of
artificial life
attempts to study and understand biological life by synthesizing artificial life forms. To paraphrase Chris Langton, the founder of the field, the goal of artificial life is to “model life as it could be so as to understand life as we know it.” Artificial life is a very broad discipline which spans such diverse topics as artificial evolution, artificial ecosystems, artificial morphogenesis, molecular evolution, and many more. Langton offers a nice overview of the different research questions studied by the discipline [6]. Artificial life shares with artificial intelligence (AI) its interest in synthesizing adaptive autonomous agents. Autonomous agents are computational systems that inhabit some complex, dynamic environment, sense and act autonomously in this environment, and by doing so realize a set of goals or tasks for which they are designed.
PYTHIA
Authors: Weerawarana Sanjiva , Houstis Elias N. , Rice John R. , Joshi Anupam , Houstis Catherine E.
Published: July 2002

Problem-solving e*nvironments (PSEs) interact with the user in a language “natural” to the associated discipline, and they provide a high-level abstraction of the underlying, computationally complex model. The knowledge-based system PYTHIA addresses the problem of (parameter, algorithm) pair selection within a scientific computing domain assuming some minimum user-specified computational objectives and some characteristics of the given problem. PYTHIA's framework and methodology are general and applicable to any class of scientific problems and solvers. PYTHIA is applied in the context of Parallel ELLPACK where there are many alternatives for the numerical solution of elliptic partial differential equations (PDEs). PYTHIA matches the characteristics of the given problem with those of PDEs in an existing problem population and then uses performance profiles of the various solvers to select the appropriate method given user-specified error and solution time bounds. The profiles are automatically generated for each solver of the Parallel ELLPACK library.—
Authors' Abstract
The Totem multiple-ring ordering and topology maintenance protocol
Authors: Agarwal D. A. , Moser L. E. , Melliar-Smith P. M. , Budhia R. K.
Published: July 2002

The Totem multiple-ring protocol provides reliable totally ordered delivery of messages across multiple local-area networks interconnected by gateways. This consistent message order is maintained in the presence of network partitioning and remerging, and of processor failure and recovery. The protocol provides accurate topology change information as part of the global total order of messages. It addresses the issue of scalability and achieves a latency that increases logarithmically with system size by exploiting process group locality and selective forwarding of messages through the gateways. Pseudocode for the protocol and an evaluation of its performance are given.
—Authors' Abstract
A theory of intersection anomalies in relational database schemes
Authors: Beeri Catriel , Kifer Michael
Published: July 2002

The desirability of acyclic database schemes is well argued in [8] and [13]. For schemas described by multivalued dependencies, acyclicity means that the dependencies do not split each other's left-hand sides and do not form intersection anomalies. In a recent work [4] it is argued that real-world database schemes always meet the former requirement, and in [5] it is shown that any given real-world scheme can be made to satisfy also the latter requirement, after being properly extended. However, the method of elimination of intersection anomalies proposed in [5] is intrinsically nondeterministic—an undesirable property for a design tool. In the present work it is shown that this nondeterminism does not, however, affect the final result of the design process. In addition, we present an efficient deterministic algorithm, which is equivalent to the nondeterministic process of [5]. Along the way a study of intersection anomalies, which is interesting in its own right, is performed.
Fibonacci heaps and their uses in improved network optimization algorithms
Authors: Fredman Michael L. , Tarjan Robert Endre
Published: July 2002

In this paper we develop a new data structure for implementing heaps (priority queues). Our structure,
Fibonacci heaps
(abbreviated
F-heaps
), extends the binomial queues proposed by Vuillemin and studied further by Brown. F-heaps support arbitrary deletion from an
n
-item heap in
O
(log
n
) amortized time and all other standard heap operations in
O
(1) amortized time. Using F-heaps we are able to obtain improved running times for several network optimization algorithms. In particular, we obtain the following worst-case bounds, where
n
is the number of vertices and
m
the number of edges in the problem graph:

O
(
n
log
n
+
m
) for the single-source shortest path problem with nonnegative edge lengths, improved from
O
(
m
log

(
m/n
+2)

n
);

O
(
n
2
log
n
+
nm
) for the all-pairs shortest path problem, improved from
O
(
nm
log

(
m/n
+2)

n
);

O
(
n
2
log
n
+
nm
) for the assignment problem (weighted bipartite matching), improved from
O
(
nm
log

(
m/n
+2)

n
);

O
(
mβ
(
m, n
)) for the minimum spanning tree problem, improved from
O
(
m
log log

(
m/n
+2)

n
); where
β
(
m, n
) = min {
i
| log

(
i
)

n
≤
m/n
}. Note that
β
(
m, n
) ≤ log
*
n
if
m
≥
n
.

Of these results, the improved bound for minimum spanning trees is the most striking, although all the results give asymptotic improvements for graphs of appropriate densities.
Random sampling with a reservoir
Authors: Vitter Jeffrey S.
Published: July 2002

We introduce fast algorithms for selecting a random sample of
n
records without replacement from a pool of
N
records, where the value of
N
is unknown beforehand. The main result of the paper is the design and analysis of Algorithm Z; it does the sampling in one pass using constant space and in
O
(
n
(1 + log(
N/n
))) expected time, which is optimum, up to a constant factor. Several optimizations are studied that collectively improve the speed of the naive version of the algorithm by an order of magnitude. We give an efficient Pascal-like implementation that incorporates these modifications and that is suitable for general use. Theoretical and empirical results indicate that Algorithm Z outperforms current methods by a significant margin.
Prefix
B
-trees
Authors: Bayer Rudolf , Unterauer Karl
Published: July 2002

Two modifications of
B
-trees are described, simple prefix
B
-trees and prefix
B
-trees. Both store only parts of keys, namely prefixes, in the index part of a
B
*
-tree. In simple prefix
B
-trees those prefixes are selected carefully to minimize their length. In prefix
B
-trees the prefixes need not be fully stored, but are reconstructed as the tree is searched. Prefix
B
-trees are designed to combine some of the advantages of
B
-trees, digital search trees, and key compression techniques while reducing the processing overhead of compression techniques.
Fact Retrieval and Deductive Question-Answering Information Retrieval Systems
Authors: Cooper William S.
Published: July 2002

Information Retrieval systems may be classified either as Document Retrieval systems or Fact Retrieval systems. It is contended that at least some of the latter will require the capability for performing logical deductions among natural language sentences. The problem of developing systems of logical inference for natural languages is discussed, and an example of such an analysis of a sublanguage of English is presented. An experimental Fact Retrieval system which incorporates this analysis has been programmed for the IBM 7090 computer, and its main algorithms are stated.
A Modified Method of Latent Class Analysis for File Organization in Information Retrieval
Authors: Winters William K.
Published: July 2002

The latent class structure is modified by requiring the number of latent classes to be equal to the number of keywords. This modification changes the latent structure to one that consists of matrices that are both symmetric and positive definite, therefore making a “computer solution” both possible and practical. The modified latent structure is derived, the numerical analysis considerations for a computer solution are presented, and an example illustrates the use of the latent class structure in both file organization and retrieval.
A Fast and Usually Linear Algorithm for Global Flow Analysis
Authors: Graham Susan L. , Wegman Mark
Published: July 2002

A new algorithm for global flow analysis on reducible graphs is presented. The algorithm is shown to treat a very general class of function spaces. For a graph of
e
edges, the algorithm has a worst-case time bound of
O
(
e
log
e
) function operations. It is also shown that in programming terms, the number of operations is proportional to
e
plus the number of exits from program loops. Consequently a restriction to one-entry one-exit control structures guarantees linearity. The algorithm can be extended to yet larger classes of function spaces and graphs by relaxing the time bound. Examples are given of code improvement problems which can be solved using the algorithm.
The Power of Dominance Relations in Branch-and-Bound Algorithms
Authors: Ibaraki Toshihide
Published: July 2002

A dominance relation
D
is a binary relation defined on the set of partial problems generated in a branch-and-bound algorithm, such that

P
i
DP
j

(where

P
i

and

P
j

are partial problems) implies that

P
j

can be excluded from consideration without loss of optimality of the given problem if

P
i

has already been generated when

P
j

is selected for the test. The branch-and-bound computation is usually enhanced by adding the test based on a dominance relation.

A dominance relation
D′
is said to be stronger than a dominance relation
D
if

P
i
DP
j

always implies

P
i
D′P
j

. Although it seems obvious that a stronger dominance relation makes the resulting algorithm more efficient, counterexamples can easily be constructed. In this paper, however, four classes of branch-and-bound algorithms are found in which a stronger dominance relation always gives a more efficient algorithm. This indicates that the monotonicity property of dominance relations would be observed in a rather wide class of branch-and-bound algorithms, thus encouraging the designer of a branch-and-bound algorithm to find the strongest possible dominance relation.