bluuebunny/crossref_metadata_2025_split huggingface dataset:
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

OBJECTIVESPropylene 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.METHODSNon-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.RESULTSAfter 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.CONCLUSIONShort 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

OBJECTIVESTo 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.METHODSFrom 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.RESULTSFor 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.CONCLUSIONSThe 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

OBJECTIVESTo 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.METHODSA 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.RESULTSObesity 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.CONCLUSIONSIn 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

Abstract
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.
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.
A modified inversion procedure for product form of the inverse linear programming codes
Authors: Larsen L. J. 
Published: July 2002

This paper describes a new algorithm for the selection of the pivot row in matrix inversion when using the product form of the inverse. This algorithm has been developed for linear programming codes; however, it would be valuable for the inversion of any non-dense matrix.
The procedures described in this paper have been thoroughly tested and have been in operation on the Esso Research and Engineering IBM 7090 computer for nine months. Substantial computer cost savings have been realized because of this procedure.
Elemental Abundances in Quasistellar Objects: Star Formation and Galactic Nuclear Evolution at High Redshifts
Authors: Hamann Fred , Ferland Gary 
Published: July 2002

▪ Abstract  Quasar (QSO) elemental abundances provide unique probes of high-redshift star formation and galaxy evolution. There is growing evidence from both the emission and intrinsic absorption lines that QSO environments have roughly solar or higher metallicities out to redshifts >4. The range is not well known, but solar to a few times solar metallicity appears to be typical. There is also evidence for higher metallicities in more luminous objects and for generally enhanced N/C and Fe/α abundances compared with solar ratios.These results identify QSOs with vigorous, high-redshift star formation—consistent with the early evolution of massive galactic nuclei or dense protogalactic clumps. However, the QSOs offer new constraints. For example, (a) most of the enrichment and star formation must occur before the QSOs “turn on” or become observable, on time scales of [Formula: see text] 1 Gyr at least at the highest redshifts. (b) The tentative result for enhanced Fe/α suggests that the first local star formation began at least ∼1 Gyr before the QSO epoch. (c) The star formation must ultimately be extensive to reach high metallicities; that is, a substantial fraction of the local gas must be converted into stars and stellar remnants. The exact fraction depends on the shape of the initial mass function (IMF). (d) The highest derived metallicities require IMFs that are weighted slightly more toward massive stars than in the solar neighborhood. (e) High metallicities also require deep gravitational potentials. By analogy with the well-known mass–metallicity relation among low-redshift galaxies, metal-rich QSOs should reside in galaxies (or protogalaxies) that are minimally as massive (or as tightly bound) as our own Milky Way.
ADAPTIVE EVOLUTION OF PHOTORECEPTORS AND VISUAL PIGMENTS IN VERTEBRATES
Authors: Yokoyama Shozo , Yokoyama Ruth 
Published: July 2002

▪ Abstract  Animals may be camouflaged by a coloration that matches their surroundings or by a combination of color and shape. Some species make themselves conspicuous and rely upon bold and bright coloration as a means of warning off their potential predators. Population biologists have accumulated information on the adaptive significance of coloration for a large number of species. To elucidate the mechanisms underpinning such natural selection events, it is necessary to understand the visual systems of interacting organisms.Molecular genetic analyses on the human opsin genes by Nathans and his colleagues made it possible to characterize the opsin genes of various vertebrates. A striking level of diversity in the opsin gene sequences reflects adaptive responses of various species to different environments. Comparative analyses of opsins reveal that gene duplications and accumulation of mutations have been important in achieving that diversity. The analyses also identify amino acid changes that are potentially important in controlling wavelength absorption by the photosensitive molecules, the visual pigments. These hypotheses can now be rigorously tested using tissue culture cells. Thanks to the molecular characterization of the opsin genes, it is now possible to study the types of opsins associated with certain environmental conditions. Such surveys will provide important first molecular clues to how animals adapt to their environments with respect to their coloration and behavior.
A Comparison of Alternative Strategies for Estimating Gene Flow from Genetic Markers
Authors: Neigel Joseph E. 
Published: July 2002

The estimation of gene flow from the distribution of genetic markers in populations requires an indirect approach. Gene flow parameters are defined by demographic models, and population genetic models provide the link between these parameters and the distributions of genetic markers. Following the introduction of allozyme methods in the 1960s, a standard approach to the estimation of gene flow was developed. Wright's island model of population structure was used to relate the distribution of allozyme alleles in populations to Nem, the product of the effective population size and the rate of migration. Alternative strategies for the estimation of gene flow have been developed using different genetic markers, different models of demography and population genetics, and different methods of parameter estimation. No alternative strategy now available is clearly superior to the standard approach based on Wright's model and allozyme markers. However, this may soon change as methods are developed that fully utilize the genealogical relationships of DNA sequences. At present, alternative strategies do fill important needs. They can provide independent estimates of gene flow, measure different components of gene flow, and detect historical changes in population structure.
Emotion, Regulation, and Moral Development
Authors: Eisenberg Nancy 
Published: July 2002

Research and theory on the role of emotion and regulation in morality have received considerable attention in the last decade. Much relevant work has concerned the role of moral emotions in moral behavior. Research on differences between embarrassment, guilt, and shame and their relations to moral behavior is reviewed, as is research on the association of these emotions with negative emotionality and regulation.Recent issues concerning the role of such empathy-related responses as sympathy and personal distress to prosocial and antisocial behavior are discussed, as is the relation of empathy-related responding to situational and dispositional emotionality and regulation. The development and socialization of guilt, shame, and empathy also are discussed briefly. In addition, the role of nonmoral emotions (e.g. anger and sadness), including moods and dispositional differences in negative emotionality and its regulation, in morally relevant behavior, is reviewed.
ARTISTIC LABOR MARKETS AND CAREERS
Authors: Menger Pierre-Michel 
Published: July 2002

▪ Abstract  Artistic labor markets are puzzling ones. Employment as well as unemployment are increasing simultaneously. Uncertainty acts not only as a substantive condition of innovation and self-achievement, but also as a lure. Learning by doing plays such a decisive role that in many artworlds initial training is an imperfect filtering device. The attractiveness of artistic occupations is high but has to be balanced against the risk of failure and of an unsuccessful professionalization that turns ideally non-routine jobs into ordinary or ephemeral undertakings. Earnings distributions are extremely skewed. Risk has to be managed, mainly through flexibility and cost reducing means at the organizational level and through multiple job holding at the individual level. Job rationing and an excess supply of artists seem to be structural traits associated with the emergence and the expansion of a free market organization of the arts.Reviewing research done not only by sociologists, but also by economists, historians and geographers, our chapter focuses on four main issues: the status of employment and career patterns, the rationales of occupational choice, occupational risk diversification, and the oversupply of artists.
Interindividual Variation in Human Visual Performance
Authors: Halpern Scott D. , Andrews Timothy J. , Purves Dale 
Published: July 2002

Abstract
The responses of 20 young adult emmetropes with normal color vision were measured on a battery of visual performance tasks. Using previously documented tests of known reliability, we evaluated orientation discrimination, contrast sensitivity, wavelength sensitivity, vernier acuity, direction-of-motion detection, velocity discrimination, and complex form identification. Performance varied markedly between individuals, both on a given test and when the scores from all tests were combined to give an overall indication of visual performance. Moreover, individual performances on tests of contrast sensitivity, orientation discrimination, wavelength discrimination, and vernier acuity covaried, such that proficiency on one test predicted proficiency on the others. These results indicate a wide range of visual abilities among normal subjects and provide the basis for an overall index of visual proficiency that can be used to determine whether the surprisingly large and coordinated size differences of the components of the human visual system (Andrews, Halpern, & Purves, 1997) are reflected in corresponding variations in visual performance.
Set-and Code-Specific Activation in the Frontal Cortex: An fMRI Study of Encoding and Retrieval of Faces and Words
Authors: McDermott Kathleen B. , Buckner Randy L. , Petersen Steven E. , Kelley William M. , Sanders Amy L. 
Published: July 2002

Abstract
The frontal cortex has been described as playing both “setspecific” and “code-specific” roles in human memory processing. Set specificity refers to the finding of goal-oriented differences in activation patterns (e.g., encoding relative to retrieval). Code specificity refers to the finding of different patterns of activation for different types of stimuli (e.g., verbal/nonverbal). Using a two (code: verbal, nonverbal) by two (set: encoding, retrieval) within-subjects design and fMRI, we explored the influence of type of code and mental set in two regions in the frontal cortex that have been previously shown to be involved in memory. A region in the dorsal extent of the inferior frontal gyrus (BA 6/44) demonstrated code-specific effects. Specifically, an interaction of material type with hemisphere was obtained, such that words produced predominantly left-lateralized activation, whereas unfamiliar faces elicited predominantly right-lateralized activation. A region of the right frontal polar cortex (in or near BA 10), which has been activated in many memory retrieval studies, showed set-specific activation in that it was more active during retrieval than encoding. These data demonstrate that distinct regions in the frontal cortex contribute in systematic yet different ways to human memory processing.
Detecting and Estimating Signals in Noisy Cable Structures, I: Neuronal Noise Sources
Authors: Manwani Amit , Koch Christof 
Published: July 2002

In recent theoretical approaches addressing the problem of neural coding, tools from statistical estimation and information theory have been applied to quantify the ability of neurons to transmit information through their spike outputs. These techniques, though fairly general, ignore the specific nature of neuronal processing in terms of its known biophysical properties. However, a systematic study of processing at various stages in a biophysically faithful model of a single neuron can identify the role of each stage in information transfer. Toward this end, we carry out a theoretical analysis of the information loss of a synaptic signal propagating along a linear, one-dimensional, weakly active cable due to neuronal noise sources along the way, using both a signal reconstruction and a signal detection paradigm. Here we begin such an analysis by quantitatively characterizing three sources of membrane noise: (1) thermal noise due to the passive membrane resistance, (2) noise due to stochastic openings and closings of voltage-gated membrane channels (Na+ and K+), and (3) noise due to random, background synaptic activity. Using analytical expressions for the power spectral densities of these noise sources, we compare their magnitudes in the case of a patch of membrane from a cortical pyramidal cell and explore their dependence on different biophysical parameters.