1,774 research outputs found

    Photons in Magnetic Fields

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    Photons in magnetic field

    Measurement of time differences between luminous events Patent

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    Mechanism for measuring nanosecond time differences between luminous events using streak camer

    Fast opening diaphragm Patent

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    Magnetically opened diaphragm design with camera shutter and expansion tube application

    Suspended particulate matter in the Chesapeake Bay entrance and adjacent shelf waters

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    Approximately 400 samples were collected from the mouth of the Chesapeake Bay for various analyses, including 138 for suspended solids. Characteristics of suspended solids that were analyzed included: total suspended matter; total suspended inorganics, total suspended organics; percent organics; particle size distribution; and presence or absence of 11 of the most prominent particle types

    Future Directions in Machine Learning

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    Parkinson's Disease: Clinical Signs and Symptoms, Neural Mechanisms, Positron Emission Tomography, and Therapeutic Interventions

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    Parkinson's disease is one of the most frequent neurodegenerative brain diseases. Its time course is slow and is characterized by progressive loss of dopaminergic and other brainstem neurons resulting in malfunctioning of the cerebral neuronal systems responsible for motor functions. The clinical signs are slowness of movement, muscle rigidity and rest-tremor amongst other features. The cause of the disease is unknown, but recently involvement of genetic factors is being researched. Positron emission tomography (PET) allows in vivo determination of striatai dopaminergic activity. This has increased our insight in the pathophysiology of the disease and permits direct study of disease progression at a biochemical level and equally to monitor whether potential neuroprotective interventions are indeed effective. Thus far no drug has emerged but promising substances are currently being studied

    A description of the GABAergic neurons and axon terminals in the motor nuclei of the cat thalamus.

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    The GABA neurons and their processes in the cat motor thalamic nuclei were identified and studied with glutamic acid decarboxylase (GAD) immunocytochemistry at both the light and electron microscopic levels. The three nuclei that comprise the motor thalamus, ventral anterior (VA), ventral medial (VM), and ventral lateral (VL), each displayed a characteristic distribution pattern of GAD-positive structures that was consistent with their afferent and intrinsic neuronal organization. All three thalamic nuclei displayed a population of small, GAD-positive cells the dendrites of which contained synaptic vesicles and participated in complex synaptic arrays such as serial synapses, triads, and glomeruli. Based on their ultrastructural features, these GAD-containing cells were identified as local circuit neurons. In contrast, the larger, GAD-negative cells were presumed to be the thalamocortical projection neurons. The axons of GAD-positive local circuit neurons could not be identified in these preparations. The number of GAD-positive dendrites in the neuropil was different for the three thalamic nuclei. In the VA and VM, the GAD-positive dendrites were numerous and formed symmetric synapses with dendrites of GAD-negative cells, mainly in association with corticothalamic boutons. Within VL, the GAD-containing dendrites were more numerous than in VA and VM and formed synapses at influential locations on presumed thalamocortical projection neurons, such as bases of primary dendrites, and bifurcation sites of primary and secondary dendrites. The VA and anterolateral VM nuclei that receive inhibitory GABAergic afferents from the entopeduncular nucleus and substantia nigra contained the highest concentration of large GAD-positive axon terminals. These boutons contained pleomorphic vesicles and numerous mitochondria and formed symmetric synapses and multiple puncta adherentes with dendrites and somata of presumed thalamocortical projection neurons. The size, ultrastructural features, and distribution of these GAD-positive boutons were similar to those features described for basal ganglia terminals in the motor thalamus of the cat. In addition, similar large-size GAD-positive boutons were observed in the medial VM, which receives basal ganglia afferents exclusively from the substantia nigra. The concentration of these terminals in medial VM along the dendrites of thalamocortical projection neurons was much less than that in VA and anterolateral VM. The VL nucleus which lacks basal ganglia input did not contain any large GAD-positive boutons.(ABSTRACT TRUNCATED AT 400 WORDS
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