1,565 research outputs found
Polyribosomes associated with synaptic specializations on axon initial segments: localization of protein-synthetic machinery at inhibitory synapses.
Previous studies have revealed a selective association between polyribosomes and axospinous synapses in a variety of brain regions. The present study evaluates whether polyribosomes are also associated with the symmetrical and presumably inhibitory synaptic connections found on the initial segment of axons of some neurons in the CNS. The initial segments of pyramidal neurons in the sensorimotor cortex of the monkey and of granule cells in the hippocampus of the rat were examined. The initial segments of these cell types are contacted by GABAergic terminals that form symmetrical synaptic connections. In the present study, these initial segments were found to contain polyribosomes that tended to be selectively localized beneath the synaptic specializations. Both the synaptic connections and the polyribosomes were localized to the initial segment; after the point at which the axon became myelinated, neither synapses nor polyribosomes were found. The association between polyribosomes and synapses was also suggested by the position of the polyribosomes with respect to the synapse. In each cell type, the majority of the polyribosomes that were present in the initial segments appeared to be localized preferentially beneath synaptic sites, although some polyribosomes were also present in the core of the axon. These data reveal that polyribosomes are not peculiar to spine synapses, but rather are ubiquitous components of the subsynaptic region of many types of synapses. We propose that neurons may regulate their innervation by positioning protein-synthetic machinery (and appropriate mRNA molecules) at particular locations in order to construct particular types of synapses at defined positions on the postsynaptic cells' receptive surface
Study of cryogenic propellant systems for loading the space shuttle
Computer programs were written to model the liquid oxygen loading system for the space shuttle. The programs allow selection of input data through graphic displays which schematically depict the part of the system being modeled. The computed output is also displayed in the form of graphs and printed messages. Any one of six computation options may be selected. The first four of these pertain to thermal stresses, pressure surges, cooldown times, flow rates and pressures during cooldown. Options five and six deal with possible water hammer effects due to closing of valves, steady flow and transient response to changes in operating conditions after cooldown. Procedures are given for operation of the graphic display unit and minicomputer
Otitis Media Supuratif Akut Di Poliklinik Tht-kl Blu RSU. Prof. Dr. R. D. Kandou Manado Periode Januari 2010-desember 2012
: Acute suppurative otitis media (ASOM) is an acute inflammation of the middle ear that lasted less than three weeks. The age factor is one of the risk factors associated with the ASOM. Children are more susceptible to ASOM, where the frequency will decrease with age. From the research ASOM most vulnerable to children due to tubal eustachius in children horizontally straight,shorter and wide. This research uses descriptive method through retrospective medical record in Ear, Nose, Throat-Head and Neck Surgery Department of Prof. R. D. Kandou General Hospital Manado on the period January 2010-December 2012
Using satellite altimetry and tide gauges for storm surge warning
The combination of the coarse temporal sampling by satellite altimeters in the deep ocean with the high temporal sampling at sparsely located tide gauges along the coast has been used to improve the forecast of high water for the North Sea along the Danish Coast and for the northeast coast of Australia. For both locations we have tried to investigate the possibilities and limitations of the use of satellite altimetry to capture high frequency signals (surges) using data from the past 20 years. The two regions are chosen to represent extra-tropical and tropical storm surge conditions. We have selected several representative high water events on the two continents based on tide gauge recordings and investigated the capability of satellite altimetry to capture these events in the sea surface height data. Due to the lack of recent surges in the North Sea we focused on general high water level and found that in the presence of two or more satellites we could capture more than 90% of the high water sea level events. In the Great Barrier Reef section of the northeast Australian coast, we have investigated several large tropical cyclones; one of these being Cyclone Larry, which hit the Queensland coast in March 2006 and caused both loss of lives as well as huge devastation. Here we demonstrate the importance of integrating tide gauges with satellite altimetry for forecasting high water at the city of Townsville in northeast Australia
Susceptibility testing and reporting of new antibiotics with a focus on tedizolid: an international working group report
Inappropriate use and overuse of antibiotics are among the most important factors in resistance development, and effective antibiotic stewardship measures are needed to optimize outcomes. Selection of appropriate antimicrobials relies on accurate and timely antimicrobial susceptibility testing. However, the availability of clinical breakpoints and in vitro susceptibility testing often lags behind regulatory approval by several years for new antimicrobials. A Working Group of clinical/medical microbiologists from Brazil, Canada, Mexico, Saudi Arabia, Russia and the UK recently examined issues surrounding antimicrobial susceptibility testing for novel antibiotics. While commercially available tests are being developed, potential surrogate antibiotics may be used as marker of susceptibility. Using tedizolid as an example of a new antibiotic, this special report makes recommendations to optimize routine susceptibility reporting
Temporal contiguity requirements for long-term associative potentiation/depression in the hippocampus
High-dose epirubicin is not an alternative to standard-dose doxorubicin in the treatment of advanced soft tissue sarcomas. A study of the EORTC soft tissue and bone sarcoma group.
The activity and toxicity of single-agent standard-dose doxorubicin were compared with that of two schedules of high-dose epirubicin. A total of 334 chemonaive patients with histologically confirmed advanced soft-tissue sarcomas received (A) doxorubicin 75 mg m(-2) on day 1 (112 patients), (B) epirubicin 150 mg m(-2) on day 1 (111 patients) or (C) epirubicin 50 mg m(-2) day(-1) on days 1, 2 and 3 (111 patients); all given as bolus injection at 3-week intervals. A median of four treatment cycles was given. Median age was 52 years (19-70 years) and performance score 1 (0-2). Of 314 evaluable patients, 45 (14%) had an objective tumour response (eight complete response, 35 partial response). There were no differences among the three groups. Median time to progression for groups A, B and C was 16, 14 and 12 weeks, and median survival 45, 47 and 45 weeks respectively. Neither progression-free (P = 0.93) nor overall survival (P = 0.89) differed among the three groups. After the first cycle of therapy, two patients died of infection and one owing to cardiovascular disease, all on epirubicin. Both dose schedules of epirubicin were more myelotoxic than doxorubicin. Cardiotoxicity (> or = grade 3) occurred in 1%, 0% and 2% respectively. Regardless of the schedule, high-dose epirubicin is not a preferred alternative to standard-dose doxorubicin in the treatment of patients with advanced soft-tissue sarcomas
Exact Solutions of Regge-Wheeler Equation and Quasi-Normal Modes of Compact Objects
The well-known Regge-Wheeler equation describes the axial perturbations of
Schwarzschild metric in the linear approximation. From a mathematical point of
view it presents a particular case of the confluent Heun equation and can be
solved exactly, due to recent mathematical developments. We present the basic
properties of its general solution. A novel analytical approach and numerical
techniques for study the boundary problems which correspond to quasi-normal
modes of black holes and other simple models of compact objects are developed.Comment: latex file, 25 pages, 4 figures, new references, new results and new
Appendix added, some comments and corrections in the text made. Accepted for
publication in Classical and Quantum Gravity, 2006, simplification of
notations, changes in the norm in some formulas, corrections in reference
Second order gauge invariant gravitational perturbations of a Kerr black hole
We investigate higher than the first order gravitational perturbations in the
Newman-Penrose formalism. Equations for the Weyl scalar representing
outgoing gravitational radiation, can be uncoupled into a single wave equation
to any perturbative order. For second order perturbations about a Kerr black
hole, we prove the existence of a first and second order gauge (coordinates)
and tetrad invariant waveform, , by explicit construction. This
waveform is formed by the second order piece of plus a term, quadratic
in first order perturbations, chosen to make totally invariant and to
have the appropriate behavior in an asymptotically flat gauge.
fulfills a single wave equation of the form where is the same wave operator as for first order perturbations and is a
source term build up out of (known to this level) first order perturbations. We
discuss the issues of imposition of initial data to this equation, computation
of the energy and momentum radiated and wave extraction for direct comparison
with full numerical approaches to solve Einstein equations.Comment: 19 pages, REVTEX. Some misprints corrected and changes to improve
presentation. Version to appear in PR
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