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PubMed2006

Interference phenomena in temporal evolution of accident probability in workplaces.

The aim of this article is to investigate some implications of complexity in workplace risk assessment. Workplace is examined as a complex system, and some of its attributes and aspects of its behavior are investigated. Failure probability of various workplace elements is examined as a time variable and interference phenomena of these probabilities are presented. Potential inefficiencies of common perceptions in applying probabilistic risk assessment models are also discussed. This investigation is conducted through mathematical modeling and qualitative examples of workplace situations. A mathematical model for simulation of the evolution of workplace accident probability in time is developed. Its findings are then attempted to be translated in real-world terms and discussed through simple examples of workplace situations. The mathematical model indicates that workplace is more likely to exhibit an unpredictable behavior. Such a behavior raises issues about usual key assumptions for the workplace, such as aggregation. Chaotic phenomena (nonlinear feedback mechanisms) are also investigated for in simple workplace systems cases. The main conclusions are (1) that time is an important variable for risk assessment, since behavior patterns are complex and unpredictable in the long term and (2) that workplace risk identification should take place in a holistic view (not by work post).

Accidents↗
PubMed1994

Cell kinetics of conjunctival and corneal epithelium during regeneration of different-sized corneal epithelial defects.

Rats with small (diam. 1.7 mm), medium sized (diam. 3.5 mm) or large (diam. 5.5 mm) corneal epithelial erosions in one eye were killed 1, 2 or 4 days after the injury. The proliferative response was evaluated by measuring the labelling index and the mitotic rate in the corneal epithelium and in the adjacent conjunctiva. The small erosions triggered a proliferative response in the cornea only with the maximum response occurring midperipherally. The medium sized erosions induced a higher and more extensive response in the cornea and also a slight increase of the labelling index in the limbal area. The large erosions induced an even more pronounced response in the peripheral cornea and an increase both of the labelling index and the mitotic rate well beyond the limbal part of the conjunctiva. It is concluded that the magnitude and the extent both of the conjunctival and the corneal regenerative response to a corneal abrasion is correlated to the size of the corneal defect. Temporary reduction in the conjunctival epithelial cell number shows that both cells in the limbal and the extralimbal conjunctiva migrate centripetally during healing of large corneal wounds. It is suggested that the stem cell theory should be modified. The limbal area is probably an area in which conjunctival epithelial cells or conjunctiva-derivated cells transform or differentiate to corneal epithelial cells.

Animals↗
PubMed1999

How strong is a covalent bond?

The rupture force of single covalent bonds under an external load was measured with an atomic force microscope (AFM). Single polysaccharide molecules were covalently anchored between a surface and an AFM tip and then stretched until they became detached. By using different surface chemistries for the attachment, it was found that the silicon-carbon bond ruptured at 2.0 +/- 0.3 nanonewtons, whereas the sulfur-gold anchor ruptured at 1.4 +/- 0.3 nanonewtons at force-loading rates of 10 nanonewtons per second. Bond rupture probability calculations that were based on density functional theory corroborate the measured values.

Journal Article↗
PubMed1992

Spontaneous congenital non-pigmented epithelial cysts of the iris stroma.

Histopathological and immunohistochemical findings in 11 patients with spontaneous congenital non-pigmented epithelial cysts of the iris stroma were studied. The cysts were lined by stratified squamous to unilayered cuboidal non-pigmented epithelium. Goblet cells were present in nine cysts, indicating a similarity to conjunctival epithelium. The demonstration of higher-molecular-weight keratins and absence of S-100 protein, by monoclonal and polyclonal antibodies, argues for surface ectodermal rather than neuroectodermal origin of the cysts. Theories of embryogenesis have been conflicting, but our results support the theory that they arise from surface ectoderm, displaced probably at the time of lens vesicle formation. The finding of normally sited subepithelial S-100 positive melanocytes may suggest that ectopic conjunctival epithelium can induce normal patterns of migration of neural crest cells.

Adolescent↗
PubMed1988

Pierre Louis Moreau de Maupertuis (1698-1759).

Maupertuis was one of the most important scientists and original thinkers of the 18th century. He refuted the preformationist theories of the time, and from his study of the inheritance of genetic traits proposed various ideas which forecast the genetic theory of inheritance. He applied the concept of probability to genetic problems and introduced experimental breeding as a means of studying the inheritance of genetic traits in animals. However, he considered his greatest contribution to science to be the 'Principle of Least Action'. Yet paradoxically it was this, through the vitriolic attacks by Voltaire which it engendered, which resulted in his work being largely ignored until recent times.

France↗
PubMed1987

The psychodynamic formulation: its purpose, structure, and clinical application.

The authors present a brief written psychodynamic formulation that focuses on central conflicts, anticipates transferences and resistances, and helps guide all psychiatric treatments. After placing the presenting problem in the context of the patient's life and identifying nondynamic determinants of the psychopathology, the formulation explains the development of central conflicts and their repetitive effect on the patient's behavior. It concludes by describing how these conflicts will be manifested in treatment. Three sample formulations and their application are presented to illustrate the value of this clinical tool.

Conflict, Psychological↗
PubMed1983

Development of carpal bone cysts as revealed by radiography.

In 11 patients with carpal bone cysts the course of the intraosseous lytic lesion could be followed over periods from 2 to 27 years. The cysts were found to develop from an area of sparse trabeculae of reduced mineral content to a well-defined cavity, in some instances surrounded by a sclerotic zone. In 2 instances the lytic process caused progressive destruction of the subchondral layers of the affected bone resulting in communication with the adjacent joint space. The findings support the theory that carpal bone cysts are intraosseous lesions probably caused by vascular disturbances from mechanical stress and repeated trauma. The term intraosseous ganglion is a misnomer and should be avoided.

Adult↗
PubMed2005

Prospective budgeting for home care: making titration work.

OBJECTIVE: To provide a model for prospective budgeting for home care that is plausible, coherent, flexible, and sufficiently tractable that it can serve as a template for practical decision making and to clarify what would be the data requirements and statistical framework to calibrate the model. METHODS: Methods used are standard risk-neutral expected value theory, cost benefit analysis, and the conditional logistic probability model. RESULTS: A simple but effective prospective budgeting model that provides analytic scaffolding for a practical decision support system for home care case managers, consultants, and program evaluators that can improve program equity, efficiency, and effectiveness. DISCUSSION: The author criticizes the well-known Titration Budgeting Model of Weissert, Chernew, and Hirth in terms of its logical and operational problems but then goes on to develop a framework within which the goals of the titration model can be met and home care resources can be more efficiently allocated.

Aged↗
PubMed1977

Depression and loss.

Recent losses occurring in the two years before onset of depression in women are distinguished from past losses occurring at any time before this. Of past losses only loss of mother before II is associated with greater risk of depression--both among women treated by psychiatrists and among women found to be suffering from depression in a random sample of 458 women living in London. Past loss of a father or sibling before 17 (or a mother between II and 17), or a child or husband, is not associated with a greater chance of developing depression. However, among patients all types of past loss by death are associated with psychotic-like depressive symptoms (and their severity) and other types of past loss with neurotic-type depressive symptoms (and their severity). It is argued that these associations probably reflect direct causal links, and a sociopsychological theory to explain them is discussed.

Adjustment Disorders↗
PubMed1998

Interpersonal schemata in child psychotherapy: a cognitive-interpersonal perspective.

Presents a cognitive-interpersonal framework for child psychotherapy derived from attachment theory. Interpersonal schema, conceptualized as expectations regarding others' probable responses to the self, are posited as a key mediating mechanism linking past interpersonal experience with current social-emotional functioning, and as an important target for intervention. Three schema-based models of pathogenic process are examined: preemptive information-processing, schema-triggered affect, and schema-primed interpersonal and emotion-regulation strategies. Implications for assessment of and intervention with interpersonal schema are considered. Preventive, compensatory, and remedial intervention strategies are proposed.

Child↗
PubMed2001

[Studies on the mechanism of subcellular distribution of basic drugs based on their lipophilicity].

This paper described the studies on the mechanism of subcellular distribution of lipophilic weak bases. Although the tissue distribution of basic drugs appeared to decrease with time simply in parallel with their plasma concentration, their subcellular distribution in various tissues exhibited a variety of patterns. Basic drugs were distributed widely in various tissues, but were concentrated in lung granule fraction, where their accumulation was dependent on their lipophilicity and lysosomal uptake. As the plasma concentration of drugs decreased after maximum level, the contribution of lysosomes to their subcellular distribution increased. The uptake of the basic drugs into lysosomes depended both on their intralysosomal pH and on the drug lipophilicity. As the lipophilicity of the basic drugs increased, they accumulated more than the values predicted from the pH-partition theory and raised the intralysosomal pH more potently, probably owing to their binding with lysosomal membranes with or without additional intralysosomal aggregation. These phenomena should be considered as a basis of drug interaction in clinical treatments.

Animals↗
PubMed1983

Applicability of a cryogradient technique for the enrichment of PAH from automobile exhausts: demonstration of methodology and evaluation experiments.

A cryogradient system for the enrichment of polycyclic aromatic hydrocarbons from gasoline and diesel powered vehicles is described. The sampling involves particle trapping on a filter followed by gas phase enrichment in three separate condensers. The filter is extracted with dichloromethane (DCM). For the extraction of the condensers three different solvents have been used; cyclohexane, acetone and DCM. The latter has also been used together with three buffers, pH 3, pH 7 and pH 11. Analyses of polynuclear aromatic hydrocarbons were performed by means of glass capillary gas chromatography and mass spectrometry. These analyses of diluted gasoline exhausts show that of the phenanthrene/anthracene, fluoranthene/pyrene and their monoalkylated forms found, between 90 and 30% are present in the gas phase. For diesel emissions, corresponding values are between 50% and 5%, respectively. However, the distribution of PAH between gas phase and particles is dependent on dilution ratio and filter temperatures. The addition of NO2 (approximately 7 ppm) prior to filter sampling involves degradation of cyclopenteno(cd)pyrene (CPedP) and benzo(a)pyrene (BaP) on the particles from diluted gasoline exhausts. This also occurs with BaP on diesel particles sampled under equivalent conditions. Mutagenicity data from these experiments support the theory of formation of direct-acting mutagens, probably due to nitration. Parallel sampling of particles with Teflon-coated and glass fiber filters does not show that components which are reactive to NO2, e.g., CPcdP, are degraded to a lower extent when glass fiber filters are used.

Air Pollutants↗
PubMed2002

Influence of lipophilicity and lysosomal accumulation on tissue distribution kinetics of basic drugs: a physiologically based pharmacokinetic model.

This paper examines the role of lipophilicity in the tissue distribution kinetics of basic drugs. Basic drugs have a large distribution volume and are distributed widely in various tissues in the following order: lung, fat, heart, kidney, brain, gut, muscle and bone. The fat volume in the whole body influences the disposition kinetics. There is a good correlation in various tissues between the tissue-plasma concentration ratio and the octanol-water partition coefficient among various drugs. We constructed a physiologically-based pharmacokinetic model on the basis of drug lipophilicity and found that drug distribution decreased when NH4Cl was administered concomitantly. In regards to subcellular distribution, the relative specific contents of chlorpromazine, imipramine and biperiden with respect to the protein in lysosomes were 7.3, 9.6 and 4.2, respectively, while those in other subcellular organella, including mitochondria, were only 0.4-1.7, indicating preferential accumulation of these drugs in lysosomes. The uptake of basic drugs into lysosomes depended on both intralysosomal pH and drug lipophilicity. As the lipophilicity of the basic drugs increased, they accumulated more than would have been predicted from the pH-partition theory and raised the intralysosomal pH more potently, probably owing to their binding with lysosomal membranes, with or without intralysosomal aggregation. We conclude that the distribution kinetics of basic drugs is driven by drug lipophilicity and uptake into lysosomes, and these phenomena provide a possible basis for drug interaction in clinical treatments.

Animals↗
PubMed2001

Experimental protocols for investigating relationships among mother-infant interaction, affect regulation, physiological markers of stress responsiveness, and attachment.

Gergely and Watson's (1996) social biofeedback theory of parental affect mirroring applies the conditional probability model of contingency perception to parent-child interactions. Infants are first evaluated at birth on neurological and temperament measures. Infants are also evaluated at 6 and 12 months on tasks that study social interactional determinants, infant attachment, and physiological reactions. The Strange Situation is completed at 12-15 months of age. The authors describe how the combination of these experimental and observational procedures allows specific developmental hypotheses to be investigated about the quality of contingent parental affect regulation, sensitivity to internal states, and security of attachment.

Affect↗
PubMed2006

Evaluation and comparison of 50 Hz current threshold of electrocutaneous sensations using different methods.

Leakage currents, tiny currents flowing from an everyday-life appliance through the body to the ground, can cause a non-adequate perception (called electrocutaneous sensation, ECS) or even pain and should be avoided. Safety standards for low-frequency range are based on experimental results of current thresholds of electrocutaneous sensations, which however show a wide range between about 50 microA (rms) and 1000 microA (rms). In order to be able to explain these differences, the perception threshold was measured repeatedly in experiments with test persons under identical experimental setup, but by means of different methods (measuring strategies), namely: direct adjustment, classical threshold as amperage of 50% perception probability, and confidence rating procedure of signal detection theory. The current is injected using a 1 cm2 electrode at the highly touch sensitive part of the index fingertip. These investigations show for the first time that the threshold of electrocutaneous sensations is influenced both by adaptation to the non-adequate stimulus and individual, emotional factors. Therefore, classical methods, on which the majority of the safety investigations are based, cannot be used to determine a leakage current threshold.The confidence rating procedure of the modern signal detection theory yields a value of 179.5 microA (rms) at 50 Hz power supply net frequency as the lower end of the 95% confidence range considering the variance in the investigated group. This value is expected to be free of adaptation influences, and is distinctly lower than the European limits and supports the stricter regulations of Canada and USA.

Adaptation, Physiological↗