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At least 1,171 records · Page 65Linked to original sources
PubMed2003

Accident prediction models for urban roads.

This paper describes some of the main findings from two separate studies on accident prediction models for urban junctions and urban road links described in [Uheldsmodel for bygader-Del1: Modeller for 3-og 4-benede kryds. Notat 22, The Danish Road Directorate, 1995; Uheldsmodel for bygader- Del2: Modeller for straekninger. Notat 59, The Danish Road Directorate, 1998] (Greibe and Hemdorff, 1995, 1988). The main objective for the studies was to establish simple, practicable accident models that can predict the expected number of accidents at urban junctions and road links as accurately as possible. The models can be used to identify factors affecting road safety and in relation to 'black spot' identification and network safety analysis undertaken by local road authorities. The accident prediction models are based on data from 1036 junctions and 142 km road links in urban areas. Generalised linear modelling techniques were used to relate accident frequencies to explanatory variables. The estimated accident prediction models for road links were capable of describing more than 60% of the systematic variation ('percentage-explained' value) while the models for junctions had lower values. This indicates that modelling accidents for road links is less complicated than for junctions, probably due to a more uniform accident pattern and a simpler traffic flow exposure or due to lack of adequate explanatory variables for junctions. Explanatory variables describing road design and road geometry proved to be significant for road link models but less important in junction models. The most powerful variable for all models was motor vehicle traffic flow.

Accidents, Traffic↗
PubMed1988

Effects of heat shock on the expression of thrombospondin by endothelial cells in culture.

Heat-shock proteins from confluent primary cultures of bovine aortic endothelial cells were analyzed by SDS-polyacrylamide gels. In addition to the increased synthesis of the classical heat-shock proteins, there is an increase of a 180,000-mol wt polypeptide in the growth media of heat-shocked cells. Immunoprecipitation with specific antiserum indicates that the 180,000-mol wt polypeptide is thrombospondin. Assay of mRNA levels coding for thrombospondin after brief hyperthermic treatment (45 degrees C, 10 min), followed by a recovery of 2 h at 37 degrees C, results in a twofold increase in mRNA abundance. In contrast, the activation level of the 71,000-mol wt heat-shock protein mRNA occurs at an earlier time than for thrombospondin mRNA. Immunofluorescence microscopy was used to study the intracellular and extracellular distribution of thrombospondin. Thrombospondin is localized to a prominent pattern of granules of intracellular fluorescence in a perinuclear distribution in cells not exposed to heat. Upon heat treatment, the pattern of granules of intracellular fluorescence appears more pronounced, and the fluorescence appears to be clustered more about the nucleus. There are at least three pools of extracellular forms of thrombospondin: (a) the fine fibrillar extracellular matrix thrombospondin; (b) the punctate granular thrombospondin; and (c) the thrombospondin found in the conditioned medium not associated with the extracellular matrix. When bovine aortic endothelial cells are exposed to heat, the extracellular matrix staining of a fibrillar nature is noticeably decreased, with an increase in the number and degree of fluorescence of focal areas where the punctate granule thrombospondin structures are highly localized. No gross morphological changes in extracellular matrix staining of fibronectin was noted. However, the intermediate filament network was very sensitive and collapsed around the nucleus after heat shock. We conclude that the expression of thrombospondin is heat-shock stimulated.

Animals↗
PubMed2000

Neural representations of skilled movement.

The frontal and parietal cortex are intimately involved in the representation of goal-directed movements, but the crucial neuroanatomical sites are not well established in humans. In order to identify these sites more precisely, we studied stroke patients who had the classic syndrome of ideomotor limb apraxia, which disrupts goal-directed movements, such as writing or brushing teeth. Patients with and without limb apraxia were identified by assessing errors imitating gestures and specifying a cut-off for apraxia relative to a normal control group. We then used MRI or CT for lesion localization and compared areas of overlap in those patients with and without limb apraxia. Patients with ideomotor limb apraxia had damage lateralized to a left hemispheric network involving the middle frontal gyrus and intraparietal sulcus region. Thus, the results revealed that discrete areas in the left hemisphere of humans are critical for control of complex goal-directed movements.

Aged↗
PubMed2000

Electrophysiological evidence for fast visual processing through the human koniocellular pathway when stimuli move.

There is increasing evidence from cellular recordings in primates and behavioral studies in humans that motion can be processed by other than the magnocellular (M) pathway and the cortical dorsal stream. Little is known about cortical processing of moving stimuli when the information is conveyed by the third retinogeniculocortical pathway - the so-called koniocellular (K) pathway. We addressed this issue in humans by studying the spatio-temporal dynamics of the brain electrical fields evoked by tritan (S-cone isolating) and luminance-defined moving stimuli. Tritan and luminance stimuli are presumably carried by the K and M pathways respectively. We found two time intervals where significant stimulus-specific electric fields were evoked: an early period between 40 and 75 ms after stimulus onset, and a later period between 175 and 240 ms. Some of these fields were identical for tritanand luminance-motion, suggesting that the processing of moving stimuli share common cortical substrates when mediated via K and M pathway input. However, tritan-motion stimuli also evoked unique electric fields that appeared earlier in time than the common motion-specific fields, indicating very fast activation of cortical areas specific to input through the K pathway. A distributed source localization procedure revealed simultaneous activation of striate and extrastriate areas even at the early processing stages, strongly suggesting a very fast activation of the visual cerebral network.

Adult↗
PubMed2004

Recent developments in tissue-type imaging (TTI) for planning and monitoring treatment of prostate cancer.

Because current methods of imaging prostate cancer are inadequate, biopsies cannot be effectively guided and treatment cannot be effectively planned and targeted. Therefore, our research is aimed at ultrasonically characterizing cancerous prostate tissue so that we can image it more effectively and thereby provide improved means of detecting, treating and monitoring prostate cancer. We base our characterization methods on spectrum analysis of radiofrequency (rf) echo signals combined with clinical variables such as prostate-specific antigen (PSA). Tissue typing using these parameters is performed by artificial neural networks. We employed and evaluated different approaches to data partitioning into training, validation, and test sets and different neural network configuration options. In this manner, we sought to determine what neural network configuration is optimal for these data and also to assess possible bias that might exist due to correlations among different data entries among the data for a given patient. The classification efficacy of each neural network configuration and data-partitioning method was measured using relative-operating-characteristic (ROC) methods. Neural network classification based on spectral parameters combined with clinical data generally produced ROC-curve areas of 0.80 compared to curve areas of 0.64 for conventional transrectal ultrasound imaging combined with clinical data. We then used the optimal neural network configuration to generate lookup tables that translate local spectral parameter values and global clinical-variable values into pixel values in tissue-type images (TTIs). TTIs continue to show cancerous regions successfully, and may prove to be particularly useful clinically in combination with other ultrasonic and nonultrasonic methods, e.g., magnetic-resonance spectroscopy.

Biopsy↗
PubMed1995

Event-related coherence during finger movement: a pilot study.

Dynamic functional coupling between contralateral sensorimotor and supplementary motor areas during unilateral finger movements is studied using event-related coherence analysis. It is demonstrated in 3 subjects that the intrinsic rhythm of the sensorimotor area (mu rhythm) is phase coupled to intrinsic rhythmic activity of the supplementary motor area during rest. With preparation and execution of discrete, unilateral finger movements, these intrinsic rhythms are desynchronized due to activation of each of the local cortical networks, and the degree of synchrony or phase consistency between these rhythms decreases.

Brain Mapping↗
PubMed1998

An investigation of environmental levels of cadmium and lead in airborne matter and surface soils within the locality of a municipal waste incinerator.

The results of an investigation into the environmental impact of heavy metals in the airborne emissions from the Baldovie municipal waste incinerator, Scotland, are presented. A sampling network of 1-km grid squares covering a 7 x 9 km area was established over the incinerator plant and its surroundings. Surface soil core samples were collected from within each 1 km2 and analysed for cadmium and lead content. The spatial distribution of lead levels in soils showed a marked variation downwind from the Baldovie incinerator in comparison with the background level for the area but remained well within the typical range of lead in rural, unpolluted, British soils. A comparison of the observed levels of lead in local soils, with the predicted downwind long-term ground level lead distribution in air indicates that atmospheric emissions of lead originating from the Baldovie incinerator directly determine concentrations of lead in soils within a radius of 5 km of the incinerator. An empirical relationship between the levels of lead in soils and the long-term levels in air was established. In the case of cadmium, the spatial distribution of the heavy metal showed neither a marked nor extensive contamination of the sampled area around the incinerator and remained within the typical range of cadmium levels in rural, unpolluted, British soils. The work concludes that atmospheric emissions of lead from the Baldovie incinerator significantly determines the local distribution of lead in soils within the immediate vicinity of the incinerator.

Air Pollutants↗
PubMed1990

Regulated expression of vimentin cDNA in cells in the presence and absence of a preexisting vimentin filament network.

Human cells were transfected with a mouse vimentin cDNA expression vector containing the hormone response element of mouse mammary tumor virus. The distribution of mouse vimentin after induction with dexamethasone was examined by indirect immunofluorescence with antivimentin antibodies specific for either mouse or human vimentin. In stably transfected HeLa cells, which contain vimentin filaments, addition of dexamethasone resulted in the initial appearance of mouse vimentin in discrete areas, usually perinuclear, that always corresponded to areas of the human filament network with the most intense fluorescence. Within 20 h after addition of dexamethasone, the mouse and human vimentin immunofluorescence patterns were identical. However, in stably transfected MCF-7 cells, which lack vimentin filaments, induction of mouse vimentin synthesis resulted in assembly of vimentin filaments throughout the cytoplasm without any obvious local concentrations. Transient expression experiments with SW-13 cell subclones that either lack or contain endogenous vimentin filaments yielded similar results to those obtained with MCF-7 and HeLa transfectants, respectively. Further experiments with HeLa transfectants were conducted to follow the fate of the mouse protein after synthesis had dropped after withdrawal of dexamethasone. The mouse vimentin-specific fluorescence was initially lost from peripheral areas of the cells while the last detectable mouse vimentin always corresponded to the human filament network with the most intense fluorescence. These studies are consistent with a uniform assembly of vimentin filaments throughout the cytoplasm and suggest that previous observations of polarized or vectorial assembly from a perinuclear area to more peripheral areas in cells may be attributable to the nonuniformly distributed appearance of vimentin filaments in immunofluorescence microscopy.

Actin Cytoskeleton↗
PubMed1996

Population networks: a large-scale framework for modelling cortical neural networks.

Artificial neural networks are usually built on rather few elements such as activation functions, learning rules, and the network topology. When modelling the more complex properties of realistic networks, however, a number of higher-level structural principles become important. In this paper we present a theoretical framework for modelling cortical networks at a high level of abstraction. Based on the notion of a population of neurons, this framework can accommodate the common features of cortical architecture, such as lamination, multiple areas and topographic maps, input segregation, and local variations of the frequency of different cell types (e.g., cytochrome oxidase blobs). The framework is meant primarily for the simulation of activation dynamics; it can also be used to model the neural environment of single cells in a multiscale approach.

Animals↗
PubMed1992

Localized basaloid follicular hamartoma.

We report a 39-year-old Japanese woman with a 30 x 10 mm, skin-colored, soft, hairless, irregularly elevated plaque in the left retroauricular area. Histologically, it consistently showed features of atypical hair follicles; some showed immaturely developed basaloid epithelial islands invaginated with condensed stromal cells, and others were replaced or associated with solid strands, branching cords, or lace-like networks of undifferentiated basaloid cells. Although the clinical appearance of a typical localized basaloid follicular hamartoma is a plaque of alopecia, this case seems to be a variant, because the histological findings are so characteristic of the entity. The relationship of basaloid follicular hamartoma to other hair-follicle derived tumors is also considered.

Adult↗
PubMed1993

Myth and reality in the rural health service crisis: facing up to community responsibilities.

Rural communities, rural advocacy organizations, and policy makers persist in perpetuating two serious but related misconceptions, namely: (1) The continuing deterioration of health services in most rural communities is primarily the result of forces and factors outside of the communities themselves, and (2) the solution to reverse this deterioration will come mainly from changes in reimbursement and other types of public policy initiatives. Overemphasis on the role of external factors has created a serious imbalance in programs, resources, and policy efforts, including those supported by the NRHA, resulting in inadequate national efforts and resources to foster community-based solutions. Suggested solutions include: (1) application by communities of a proven set of principles for organizing and developing local health services, and (2) creation of a national network to promote such community-based solutions.

Catchment Area, Health↗
PubMed1998

Doing research in general practice: advice for the uninitiated.

There is increasing recognition of the importance of primary care research in relation to diabetes. Doing research in general practice is in many ways different from the hospital setting. This article considers some of the potential barriers to doing valid and reliable research in general practice. It is written for both novice researchers and researchers new to the general practice setting. Careful initial definition of the research question is crucial, especially as the clinical material may be less well defined in general practice and patients' problems need addressing on many levels (physical, psychological, social, cultural). Searching the literature for general practice-based studies is not straightforward. If your study involves more than one geographical site you may have to obtain ethical approval from multiple research ethical committees, and it is prudent to discuss your research with the Local Medical Committee. Practical advice is given on working with practices: improving response rates from questionnaires; recruiting and retaining practices; 'getting hold' of the GPs; particular difficulties related to novice or experienced practices; ensuring uniformity of methodology; and the importance of ancillary staff. Contentious issues such as money should be discussed at the outset. Many areas of the country now have General Practice Research Networks, and many of these now have NHS R&D support funding. Training in research methodology can be accessed through the Association of University Departments of General Practice or Royal College of General Practitioners or local departments of general practice. A list of useful contacts is given.

Ethics↗
PubMed2003

[EMI net--electronic medical record sharing in local community for home care medicine].

An electronic medical information network (EMI net) includes patient records from more than 40 facilities in Matsudo City and it is now used especially to improve the communication between doctors and nurses who visit patients' home. This fact suggests the importance of a medical information sharing system in a local area for home care medicine. An infrastructure connecting facilities to share the database of the patient records is essential for home care medicine performed by a multidisciplinary team beyond one medical facility.

Community Networks↗
PubMedDate not supplied

Divide-and-conquer approach for brain machine interfaces: nonlinear mixture of competitive linear models.

This paper proposes a divide-and-conquer strategy for designing brain machine interfaces. A nonlinear combination of competitively trained local linear models (experts) is used to identify the mapping from neuronal activity in cortical areas associated with arm movement to the hand position of a primate. The proposed architecture and the training algorithm are described in detail and numerical performance comparisons with alternative linear and nonlinear modeling approaches, including time-delay neural networks and recursive multilayer perceptrons, are presented. This new strategy allows training the local linear models using normalized LMS and using a relatively smaller nonlinear network to efficiently combine the predictions of the linear experts. This leads to savings in computational requirements, while the performance is still similar to a large fully nonlinear network.

Artificial Intelligence↗
PubMed2004

Cu, Pb and Zn contamination in Nuuanu watershed, Oahu, Hawaii.

Trace metal contamination in urban aquatic ecosystems in Hawaii is a significant problem, especially in terms of Cu, Pb, and Zn. These trace metals are linked to automobile usage. An in-depth study was designed to determine the influence of road sediments and storm sewers on bioavailable (0.5 M HCl) trace metal concentrations in bed sediments of Nuuanu stream, Oahu. Lead was the most enriched trace metal in the watershed. Compared to baseline Pb concentrations of <3 mg/kg, road sediments averaged 186 mg/kg, with a maximum value of 3140 mg/kg. Stream bed sediments had average Pb values of 122 mg/kg, with a maximum of 323 mg/kg. Al-normalized enrichment ratios (ERs) for the <63 microm fraction indicated that the watershed was significantly polluted in the lower, urbanized reaches, with maximum ER values of 560 and 94 for Pb in road sediments and stream sediments, respectively. Median ER values for Cu, Pb, and Zn in stream sediments were 2, 36, and 5, respectively. Rainfall events prior to sediment sampling masked any influence that storm sewer outlets might have had on the localized spatial distribution of metals associated with bed sediments. However, there was a general pattern of increasing trace metal concentrations downstream as the fluvial network traversed residential areas and commercial, highly trafficked areas in the lower portions of the watershed.

Biological Availability↗
PubMed1982

Occult iris erosion. A treatable cause of recurrent hyphema in iris-supported intraocular lenses.

A 78-year-old man underwent intracapsular cataract extraction with implantation of a Binkhorst four-loop lens. Two years later he developed recurrent hyphema, glaucoma, diffusion of blood into the vitreous, and reduction of visual acuity to 3/200. Iris fluorescein angiography demonstrated a localized network of prominent collateral vessels without fluorescein leakage above the pupil, deflection and compression of radial iris vessels by the superior lens posts, and a focal area of leakage adjacent to one of the posts. Argon laser photocoagulation obliterated the abnormal vessels in each of these areas, eliminated the recurrent hyphema and glaucoma, and permitted recovery of 20/80 visual acuity. The patient died suddenly three months after iris photocoagulation. Histopathologic study of the eye demonstrate erosion of iris stroma and displacement of iris vessels by the lens posts, as well as the vascular effects of successful photocoagulation therapy.

Aged↗
PubMed1998

Understanding rural and remote divisions under a workforce framework.

In Australia, divisions of general practice are the organisational structures for local networks of general practitioners. They facilitate communication across the profession and with other parts of the health system and are established in urban, rural and remote areas. Funding is provided contractually to divisions through the Federal Government's Divisions and Projects Grants Program. The under-supply of doctors and other health professionals in rural and remote areas of Australia is a serious problem that has far-reaching effects. The present paper argues that if the Divisions and Projects Grants Program is to be effective in achieving its aims and objectives, then the Program's policies must be responsive to the different needs, roles, constraints, expectations and capabilities of divisions and their members as well as the structural impediments imposed by the medical workforce.

Australia↗
PubMed2006

[Uveal melanoma].

The paper present a clinic and histological study, including all cases of uveal malignant tumours, hospitalized in Ophthalmological Clinic of Craiova in the last 15 years. The follow-up period of cases were 4 years. The diagnosis was established by clinic and paraclinic examination (imaging methods-- MRI, CT, Echo) and histologic examination. The histologic examination has been done for all cases. There were investigated several parametres: tumour cytology, the level of pigmentation, intravascular embolus, sclera infiltration, vascular invasion, vascular pattern, tumoral necrosis, mitotic activity. The histologic aspects of tumoral progression were: the high level mitotic activity, high surface area of intratumoral necrosis, the infiltrative process to the vessels, sclera, and ciliary body. The arcuat and network vascular patterns were involved in the systemic metastasis and local invasion. The most predominant type of cellularity related with a severe evolution of cases were the epithelioid cells and the mixed type cells.

Adult↗