Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Local Area Networks”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,261 records · Page 70Linked to original sources
PubMed2004

Metapopulation genetic structure of two coexisting parasitoids of the Glanville fritillary butterfly.

We investigated the metapopulation genetic structure of two specialist parasitoids, Cotesia melitaearum and Hyposoter horticola, attacking the Glanville fritillary butterfly (Melitaea cinxia) in the Aland Islands south-western Finland. The host butterfly persists as a classic metapopulation in a network of 4,000 small habitat patches within an area of 50 by 70 km . The two parasitoids are known to differ greatly in their population dynamics and spatial pattern of occupancy in local host populations. Analysis of genetic population structure using F(ST) and clustering of multilocus genotypes revealed a distinct large-scale spatial structure in C. melitaearum but a very weak pattern in H. horticola. This result is consistent with the known difference in the dispersal range (much longer in H. horticola) and population size (much greater in H. horticola) of the two parasitoids.

Animals↗
PubMed2005

Toward a neighborhood resource-based theory of social capital for health: can Bourdieu and sociology help?

Within the past several years, a considerable body of research on social capital has emerged in public health. Although offering the potential for new insights into how community factors impact health and well being, this research has received criticism for being undertheorized and methodologically flawed. In an effort to address some of these limitations, this paper applies Pierre Bourdieu's (1986) [Bourdieu, P. (1986). Handbook of theory and research for the sociology of education (pp. 241-258). New York: Greenwood] social capital theory to create a conceptual model of neighborhood socioeconomic processes, social capital (resources inhered within social networks), and health. After briefly reviewing the social capital conceptualizations of Bourdieu and Putnam, I attempt to integrate these authors' theories to better understand how social capital might operate within neighborhoods or local areas. Next, I describe a conceptual model that incorporates this theoretical integration of social capital into a framework of neighborhood social processes as health determinants. Discussion focuses on the utility of this Bourdieu-based neighborhood social capital theory and model for examining several under-addressed issues of social capital in the neighborhood effects literature and generating specific, empirically testable hypotheses for future research.

Behavioral Research↗
PubMed2001

The challenge and potential of childhood immunization registries.

Recent efforts to attain near-complete coverage of child populations by recommended vaccines have included initiatives by federal and state agencies, as well as private foundations, to develop and implement statewide or community-based childhood immunization registries. Plans for a single, national registry have been set aside in favor of a national network of local and state registries linked through the use of common definitions and unique child identifiers. However, both operational/technical and financing difficulties have slowed their development. The experience to date in selected areas has provided useful lessons for further development of a registry system and has underscored the potential of such systems to assure the success of childhood immunization initiatives.

Child Welfare↗
PubMed1988

Degeneration and regrowth of adrenergic nerves after microvascular anastomosis. A fluorescence histochemical study on end-to-end anastomoses of femoral vessels in the rat.

The normal femoral artery and its branches were found to be innervated with a dense network of adrenergic nerves. The nerve plexus around the vein was sparse. Adventitial stripping of the femoral vessels, with or without division and reanastomosis, caused local disappearance of catecholamine fluorescence in the stripped area. The distal adrenergic innervation remained normal if the femoral nerve was left intact. Division of the femoral nerve, alone or in combination with blood vessel division and reanastomosis, caused total disappearance of catecholamine fluorescence from the adrenergic nerves of the entire distal neurovascular tree examined. At the end of the observation period of 36 weeks from the time of division of the nerve, artery and vein with subsequent microvascular anastomosis, numerous adrenergic nerves were observed to have crossed the suture line. The vascular nerve plexus around the femoral vessels was dense in places, but in other places sparse or absent. It seems that the reinnervation occurs not only over the suture line, but also together with other regenerating nerves from the adjacent tissues and by collateral sprouting from adjacent adrenergically normally innervated areas.

Adrenergic Fibers↗
PubMed2002

Detecting climate-related trends in streamflow data.

This paper reviews the results of a number of studies that have investigated streamflow data for the existence of trend. These studies provide evidence that trends in various, but not all, streamflow regimes are occurring at rates that are higher than one might attribute to chance alone. Results of different studies using different approaches were compared and were shown, at times, to have dramatic differences. These differences might potentially be due to pre-conditioning of data prior to trend detection in attempts to minimize the impacts of serial correlation on testing procedures. It was also evident that patterns of trend can vary over small spatial scales and that a relatively high-density network is required to effectively comprehend trend and how it might be altering across an area. A global network of streamflow sites representing pristine or stable conditions is needed to assess patterns of change. Selection criteria for sites within such a network are provided, and it is highlighted that local knowledge is required to perform this selection.

Climate↗
PubMed2005

Altered environment and risk of malaria outbreak in South Andaman, Andaman & Nicobar Islands, India affected by tsunami disaster.

BACKGROUND: Pools of salt water and puddles created by giant waves from the sea due to the tsunami that occurred on 26th December 2004 would facilitate increased breeding of brackish water malaria vector, Anopheles sundaicus. Land uplifts in North Andaman and subsidence in South Andaman have been reported and subsidence may lead to environmental disturbances and vector proliferation. This warrants a situation analysis and vector surveillance in the tsunami hit areas endemic for malaria transmitted by brackish water mosquito, An. sundaicus to predict the risk of outbreak. METHODS: An extensive survey was carried out in the tsunami-affected areas in Andaman district of the Andaman and Nicobar Islands, India to assess the extent of breeding of malaria vectors in the habitats created by seawater flooding. Types of habitats in relation to source of seawater inundation and frequency were identified. The salinity of the water samples and the mosquito species present in the larval samples collected from these habitats were recorded. The malaria situation in the area was also analysed. RESULTS: South Andaman, covering Port Blair and Ferrargunj sub districts, is still under the recurring phenomenon of seawater intrusion either directly from the sea or through a network of creeks. Both daily cycles of high tides and periodical spring tides continue to cause flooding. Low-lying paddy fields and fallow land, with a salinity ranging from 3,000 to 42,505 ppm, were found to support profuse breeding of An. sundaicus, the local malaria vector, and Anopheles subpictus, a vector implicated elsewhere. This area is endemic for both vivax and falciparum malaria. Malaria slide positivity rate has started increasing during post-tsunami period, which can be considered as an indication of risk of malaria outbreak. CONCLUSION: Paddy fields and fallow land with freshwater, hitherto not considered as potential sites for An. sundaicus, are now major breeding sites due to saline water. Consequently, there is a risk of vector abundance with enhanced malaria transmission potential, due to the vastness of these tsunami-created breeding grounds and likelihood of them becoming permanent due to continued flooding in view of land subsidence. The close proximity of the houses and paucity of cattle may lead to a higher degree of man/vector contact causing a threat of malaria outbreak in this densely populated area. Measures to prevent the possible outbreak of malaria in this tsunami-affected area are discussed.

Animals↗
PubMed2003

Functional relation between interneuron input and population activity in the rat hippocampal cornu ammonis 1 area.

Inhibitory interneurons are important components of the cornu ammonis 1 (CA1) network, as they are strategically positioned to control network information transfer. We investigated in detail synaptic input to individual CA1 interneurons (mainly basket and bistratified cells) after the local circuit was activated through the Schaffer-Commissural pathway and related this input to the population activity of the pyramidal cells. Synaptic responses were measured under whole-cell voltage clamp and population activity was determined from local field potentials. The synaptic input that was evoked in CA1 interneurons fell into two distinct groups. Disynaptic input with a long latency always started after the population spike with a mean latency of 3.0+/-0.3 ms (n=22) in respect to the peak of the population spike. This type of synaptic input to the interneurons was causally linked to the occurrence and amplitude of the population spike and most likely driven by CA1 pyramidal cells. Short-latency monosynaptic input occurred 0.8+/-0.2 ms (n=18) before the peak of the population spike. Its timing was strictly linked to the stimulus and showed significantly less jitter than long-latency input. In the absence of a population spike only short-latency input could be observed. Whether an interneuron receives direct monosynaptic Schaffer input or disynaptic input from the pyramidal cell population determines when that interneuron will be recruited in the network after Schaffer collateral stimulation. In addition, we found that the relation between the strength of the synaptic input and the population activity was different for the two types of input. Short-latency monosynaptic input showed large sensitivity to input changes at stimulus intensities that evoked little activity in the pyramidal cell population. In contrast, the amplitude of the long-latency disynaptic input to the interneurons closely reflected the population activity and increased gradually with stimulus intensity. Interneurons receiving the first type of input may expand the input sensitivity of the network, while interneurons receiving the second type could be involved in overall normalization of the output of the CA1 network. Our results underscore the importance of knowledge of the input to an interneuron for the understanding of its inhibitory role in the network.

Animals↗
PubMed1992

Metabolic impairment in human amnesia: a PET study of memory networks.

Human amnesia is a clinical syndrome exhibiting the failure to recall past events and to learn new information. Its "pure" form, characterized by a selective impairment of long-term memory without any disorder of general intelligence or other cognitive functions, has been associated with lesions localized within Papez's circuit and some connected areas. Thus, amnesia could be due to a functional disconnection between components of this or other neural structures involved in long-term learning and retention. To test this hypothesis, we measured regional cerebral metabolism with 2-[18F]fluoro-2-deoxy-D-glucose ([18F]FDG) and positron emission tomography (PET) in 11 patients with "pure" amnesia. A significant bilateral reduction in metabolism in a number of interconnected cerebral regions (hippocampal formation, thalamus, cingulate gyrus, and frontal basal cortex) was found in the amnesic patients in comparison with normal controls. The metabolic impairment did not correspond to alterations in structural anatomy as assessed by magnetic resonance imaging (MRI). These results are the first in vivo evidence for the role of a functional network as a basis of human memory.

Adult↗
PubMed1994

Managed care plans: characteristics, growth, and premium performance.

Over the past dozen years, network-based managed care plans have undergone a remarkable transformation. At the beginning of the 1980s, managed care plans occupied a niche in a marketplace dominated by indemnity insurance plans. By 1993, managed care plans accounted for a growing majority of health plan enrollees. Moreover, enrollment in newer forms of managed care quickly surpassed that of the older group and staff model HMOs. Beginning as hybrids of elements of group and staff model HMO plans and of the old FFS system, these newer types of network-based plans have evolved as they have grown. Reacting to rapidly rising health care premium costs, employers wanted to move their employees and dependents relatively quickly into managed care plans. However, employers and enrollees were not prepared to make a rapid, wholesale shift from indemnity insurance and FFS towards the older, more restrictive type of group and staff model HMO plans. Moreover, intermediaries and providers were not prepared to accommodate such a shift, even if employers and employees wanted it to take place. Indeed, many of the major actors--employers, enrollees, health benefit intermediaries, physician networks, medical groups, hospitals and integrated delivery systems--have had to ascend very substantial managed care "learning curves". Although we have witnessed the overall movement of many enrollees from managed care plans that closely resembled the indemnity insurance plans toward plans with more similarities to the group and staff model HMOs, the extent of the changes has varied markedly among the dozens of local market areas, and even within local market areas. As the health care system evolves, the number and complexity of different types of contractual managed care relationships are increasing almost exponentially. The resulting difficulty in classifying managed care plans has implications for health services researchers. Increasingly, it is important to compare performance among health plans not at the level of the entire health plan, but at the level of the provider organizations or networks that actually provide health care services to enrollees. The Medical Outcome Study adopted this approach (12, 21, 35), providing useful insights into the dual effects of risk-sharing and provider organization on health care utilization, quality of care, and enrollee satisfaction. As well, if managed care plan classifications are to be meaningful, it is important to clearly specify the characteristics of the provider organization and the rest of the delivery system in whatever research is undertaken.(ABSTRACT TRUNCATED AT 400 WORDS)

Health Care Reform↗
PubMed1997

Neural mechanisms involved in the processing of global and local aspects of hierarchically organized visual stimuli.

We investigated the functional anatomy involved in sustaining or switching visual attention between different perceptual levels, using functional imaging measures of neural activity. Two experiments were carried out using hierarchically organized letters (i.e. large letters made out of small letters). In a divided-attention task, subjects were required to switch attention between local and global levels. The number of successive stimuli for which subjects had to sustain attention to either the global or local level co-varied significantly with temporal-parietal activations bilaterally. Other activations were also observed in the right orbitofrontal cortex, the right dorsolateral prefrontal cortex, and the right middle temporal gyrus. The number of switches between levels co-varied significantly with activations in the left supplementary motor area and the left medial parietal cortex. In the directed-attention task, subjects were required to attend to either the global or local level of the stimuli throughout all trials; attention to the global aspect resulted in significant activation of the right lingual gyrus while attention to the local aspect significantly activated the left inferior occipital cortex. We suggest that left hemisphere activations with increasing numbers of switches between perceptual levels reflect increased demands on an executive attentional system, while sustained attention to either level activates a predominantly right hemispheric network involving temporal-parietal and dorsolateral prefrontal regions. Overall, the results provide evidence for relative hemispheric specialization for global and local processing in accordance with previous neuropsychological studies. In addition, the findings demonstrate that early visual processing mechanisms in the prestriate cortex are influenced by an attentional system in temporal-parietal areas.

Adult↗
PubMed1990

Angiotensin II immunoreactivity in the vegetative regions of the thoracic and sacral spinal cord of guinea pig and rat.

The localization of angiotensin-II immunoreactivity (Ang-II-IR) has been studied in the thoracic and sacral spinal cord vegetative regions of male and female guinea pigs and rats. Immunoreactivity is located in varicose nerve fibers and axon terminals throughout the studied areas. We have not observed any immunoreactive neurons in these regions. The highest density of IR structures was observed in the thoracic and sacral vegetative networks of both studied species (Galabov and Davidoff, 1976; Galabov, 1978). Additionally IR fibers and terminals were found between the ependymocytes and in close contact with blood vessels. Slight immunostaining of the apical poles of the ependymocytes was observed too. These localizations of the IR fibers and terminals suggest that Ang II has important functional significance in the regulation of the vegetative activity, and plays some role in the local blood flow regulation. As to the origin of the Ang II-IR fibers and terminals most probably they are coming from higher levels of the central nervous system (brainstem and hypothalamus).

Angiotensin II↗
PubMed2003

Distribution of a novel avian gonadotropin-inhibitory hormone in the quail brain.

We recently identified a novel hypothalamic neuropeptide inhibiting gonadotropin release in the quail brain and termed it gonadotropin inhibitory hormone (GnIH). In this study, we investigated the localization and distribution of GnIH in both sexes of adult quails by immunohistochemistry with a specific antiserum against GnIH and in situ hybridization. Quantitative analysis demonstrated that the concentration of GnIH in the diencephalon was greater than that in the mesencephalon without sex difference. GnIH concentrations in the cerebrum and cerebellum were below the level of detectability. Clusters of GnIH-like immunoreactive (GnlH-ir) cell bodies were localized in the paraventricular nucleus (PVN) of the hypothalamus. There was no significant difference in the number of GnlH-ir cells in the PVN between males and females. By double immunostaining with antisera reacting with GnIH or avian posterior pituitary hormones (vasotocin and mesotocin), GnIH-ir cells were found to be parvocellular neurons in the ventral portion of PVN, which showed no immunoreaction with the antisera against vasotocin and mesotocin. In situ hybridization revealed the cellular localization of GnIH mRNA in the PVN. GnIH-ir nerve fibers were however widely distributed in the diencephalic and mesencephalic regions. Dense networks of immunoreactive fibers were found in the ventral paleostriatum, septal area, preoptic area, hypothalamus, and optic tectum. The most prominent fibers were seen in the median eminence of the hypothalamus and the dorsal motor nucleus of the vagus in the medulla oblongata. Thus, GnIH may participate not only in neuroendocrine functions, but also in behavioral and autonomic mechanisms.

Animals↗
PubMed2004

Convolutional face finder: a neural architecture for fast and robust face detection.

In this paper, we present a novel face detection approach based on a convolutional neural architecture, designed to robustly detect highly variable face patterns, rotated up to +/-20 degrees in image plane and turned up to +/-60 degrees, in complex real world images. The proposed system automatically synthesizes simple problem-specific feature extractors from a training set of face and nonface patterns, without making any assumptions or using any hand-made design concerning the features to extract or the areas of the face pattern to analyze. The face detection procedure acts like a pipeline of simple convolution and subsampling modules that treat the raw input image as a whole. We therefore show that an efficient face detection system does not require any costly local preprocessing before classification of image areas. The proposed scheme provides very high detection rate with a particularly low level of false positives, demonstrated on difficult test sets, without requiring the use of multiple networks for handling difficult cases. We present extensive experimental results illustrating the efficiency of the proposed approach on difficult test sets and including an in-depth sensitivity analysis with respect to the degrees of variability of the face patterns.

Algorithms↗
PubMed1986

"Bi-digital o-ring test molecular identification and localization method" and its application in imaging of internal organs and malignant tumors as well as identification and localization of neurotransmitters and micro-organisms--Part 1.

Using the "Bi-Digital O-Ring Test Molecular Identification and Localization Method," one can identify and localize minute amounts of bioactive substances (including neurotransmitters), micro-organisms, toxic substances, or drugs, and, in addition, one can non-invasively image normal organs as well as screen for and image the distribution of specific types of cancer of specific internal organs without using any expensive instrumentation. One can also use this method to perform a qualitative analysis of neurotransmitters, neuromodulators, and hormones on different parts of the imaged organs. The molecule or substance being investigated is compared with a minute amount of a pure control reference substance, and if the substance identical to the control reference substance exists, then the electro-magnetic waves emitted by the identical substance will produce an electro-magnetic resonance phenomenon with the electro-magnetic waves of identical resonance frequency emitted by the control reference substance, and this resonance phenomenon is hypothesized to be the basis of the "Bi-Digital O-Ring Test Molecular Identification and Localization Method." The following substances have been used as control reference substances to identify and localize identical substances in vitro and in vivo: pure neurotransmitters (e.g. serotonin, beta-endorphin, methionine-enkephalin, norepinephrine, dopamine, L-dopa, substance P, etc.), as well as L-tryptophan and L-tyrosine; cholesterol; steroid hormones (including aldosterone, corticosterone, cortisol, progesterone, testosterone, etc.); peptide hormones; microscopic slides of normal organs; microscopic slides of specific cancer cells of specific organs (e.g. adenocarcinoma of the head of the pancreas, adenocarcinoma of the descending colon, etc.); microscopic slides of pure micro-organisms; toxic substances (e.g. lead, mercury, KCN); drugs (including non-steroidal anti-inflammatory drugs, antibiotics, beta-blockers, calcium channel blockers, etc.); and antibodies against specific substances or micro-organisms. An intensive network of serotonin and L-tryptophan was discovered, by using the "Bi-Digital O-Ring Test Molecular Identification and Localization Method," in different parts of the body. In general, in painful areas, frequently serotonin is markedly reduced, L-tryptophan is markedly increased, and substance P is markedly increased, while in non-painful areas, serotonin is markedly increased, L-tryptophan is markedly decreased, and substance P is markedly decreased.(ABSTRACT TRUNCATED AT 400 WORDS)

Adult↗
PubMed2006

Surgical service centralisation in Australia versus choice and quality of life for rural patients.

High patient volume for both hospitals and surgeons is an important determinant of operative mortality and outcome for complex and infrequently performed operations. The 13% of Australia's population who live in rural and remote areas often choose to have surgery close to home and support networks despite the potentially higher operative mortality and morbidity. Rural patients should be able to make an informed choice about having their surgery locally. Rural and metropolitan surgeons should discuss and reach mutual agreement on where each patient is best treated. A balance must be struck between quality of services that can be provided locally and geographic convenience.

Australia↗
PubMed2001

[Cerebral imaging in childhood epilepsy: what's new?].

The important development of non invasive techniques of cerebral imaging dramatically improved the presurgical work-up and the study of mental sequelae in childhood epilepsy. MRI's spatial resolution improved, so it is possible to detect subtle epileptogenic lesions, even in very young patients. By visualizing more and more accurately the sulcogyral macroanatomy, MRI permits a genetic and syndromic approach of cerebral lesions associated with epilepsy. Ictal SPECT helps localizing the epileptogenic zone and placing intracranial EEG electrodes, using strict methodology with simultaneous video-EEG and multidisciplinary interpretation of the images. Functional MRI can localize motor cortex and language networks, as well as it can lateralize language with a good correlation with WADA test, using selected activation tasks in cooperative children. Interictal SPECT and PET show the dysfunctioning areas involved in the neuropsychological and behavioural disorders associated with epilepsy. Finally, fMRI may study post-lesional and post-surgical plasticity by comparing longitudinal studies in a given patient.

Brain↗
PubMed2001

The expression of vimentin in HL-60 cells induced with etoposide using immunofluorescence and immunogold methods.

HL-60 leukemic cells were treated with 6 different doses of etoposide for 72 hours. Changes in the distribution of vimentin were found to be dependent on the concentration of etoposide. As compared with control cells there were distinct changes in cells incubated with 100 and 200 microM/L of the drug. The size of cells treated with 100 microM/L and especially with 200 microM/L increased, but the number of cells decreased. In control cells and those treated with 0.02, 0.2 and 2 microM/L etoposide, vimentin was seen rather as a ring often with the increased concentration near one pole of the cells. Cells at 20 microM/L etoposide showed the same staining pattern but more brighter cells were found. The addition of 100 microM/L and 200 microM/L etoposide to cells resulted in diffusely distributed fluorescence staining, which often appeared as a quite dense network around the nucleus. Immunogold labelling was observed in cells treated with all doses of etoposide and control cells. Labelling was localized in the nucleus but also in the cytoplasm but rather in the area of the nucleus.

Antineoplastic Agents↗
PubMed2006

Cortical and thalamic coherence during spike-wave seizures in WAG/Rij rats.

The study examines cortico-cortical and cortico-thalamic network synchronization at the onset of spike-wave discharges (SWD) in a genetic model of absence epilepsy, WAG/Rij rats. Coherence was measured between multiple cortical areas (intracortical), reticular and rely thalamic nuclei (intrathalamic) and between the cortex and the thalamus. SWD-related increase of coherence (5-60 Hz) was found in all investigated pairs. The highest increase of coherence was around the mean frequency of SWD (8-11.5 Hz) and in the harmonic band 16-21.5 Hz with two central maxima around 10 and 20 Hz. The frequency profile of coherence was different in different intracortical networks, therefore latter were divided into local, global and transhemispheric networks. The presumable source of SWD in the somatosensory cortex and its closest surroundings formed a minimal (local) circuit, in which occurrence of SWD was facilitated by a consistent shift of network synchrony from delta to alpha/beta frequencies. Transhemispheric coherence revealed the largest increase with an additional 16 Hz peak, suggesting a crucial involvement of the corpus callosum in the pathophysiology of absence seizures. The increase in interhemispheric coherence was largest between relatively remote somatosensory or frontal areas, supporting the assumption that SWD originate from the lateral fronto-parietal cortical area.

Analysis of Variance↗