2,232 research outputs found
Evidence for Ordered Magnetic Fields in the Quasar Environment
At a distance of 20 pc from the purported supermassive black hole powering
quasars, temperatures and densities are inferred from optical observations to
be ~10**4 K and ~10**4 cm**-3. Here we present Very Long Baseline
Interferometry radio observations revealing organized magnetic fields on the
parsec scale in the hot plasma surrounding the quasar OQ172 (1442+101). These
magnetic fields rotate the plane of polarization of the radio emission coming
from the core and inner jet of the quasar. The derived rotation measure (RM) is
40,000 rad m**-2 in the rest frame of the quasar. Only 10 mas (a projected
distance of 68 pc) from the nucleus the jet absolute values of RM fall to less
than 100 rad m**-2.Comment: in press at ApJ Letters, 12 page LaTeX document includes 4 postscript
figure
Two-Dimensional Central-Upwind Schemes for Curvilinear Grids and Application to Gas Dynamics with Angular Momentum
In this work we present new second order semi-discrete central schemes for
systems of hyperbolic conservation laws on curvilinear grids. Our methods
generalise the two-dimensional central-upwind schemes developed by Kurganov and
Tadmor. In these schemes we account for area and volume changes in the
numerical flux functions due to the non-cartesian geometries. In case of
vectorial conservation laws we introduce a general prescription of the
geometrical source terms valid for various orthogonal curvilinear coordinate
systems. The methods are applied to the two-dimensional Euler equations of
inviscid gas dynamics with and without angular momentum transport. In the
latter case we introduce a new test problem to examine the detailed
conservation of specific angular momentum.Comment: 38 pages, 1
Interim Report
Author: F. R. Rodgers for N. H. Taylor for Sage Improvement CommitteeReason: C. W. Farr reviewing for declassificationMemo regarding 1956 interim repor
Physostigmine and Methylphenidate Induce Distinct Arousal States During Isoflurane General Anesthesia in Rats
BACKGROUND: Although emergence from general anesthesia is clinically treated as a passive process driven by the pharmacokinetics of drug clearance, agents that hasten recovery from general anesthesia may be useful for treating delayed emergence, emergence delirium, and postoperative cognitive dysfunction. Activation of central monoaminergic neurotransmission with methylphenidate has been shown to induce reanimation (active emergence) from general anesthesia. Cholinergic neurons in the brainstem and basal forebrain are also known to promote arousal. The objective of this study was to test the hypothesis that physostigmine, a centrally acting cholinesterase inhibitor, induces reanimation from isoflurane anesthesia in adult rats. METHODS: The dose-dependent effects of physostigmine on time to emergence from a standardized isoflurane general anesthetic were tested. It was then determined whether physostigmine restores righting during continuous isoflurane anesthesia. In a separate group of rats with implanted extradural electrodes, physostigmine was administered during continuous inhalation of 1.0% isoflurane, and the electroencephalogram changes were recorded. Finally, 2.0% isoflurane was used to induce burst suppression, and the effects of physostigmine and methylphenidate on burst suppression probability (BSP) were tested. RESULTS: Physostigmine delayed time to emergence from isoflurane anesthesia at doses ≥0.2 mg/kg (n = 9). During continuous isoflurane anesthesia (0.9% ± 0.1%), physostigmine did not restore righting (n = 9). Blocking the peripheral side effects of physostigmine with the coadministration of glycopyrrolate (a muscarinic antagonist that does not cross the blood-brain barrier) produced similar results (n = 9 each). However, during inhalation of 1.0% isoflurane, physostigmine shifted peak electroencephalogram power from δ ( < 4 Hz) to θ (4-8 Hz) in 6 of 6 rats. During continuous 2.0% isoflurane anesthesia, physostigmine induced large, statistically significant decreases in BSP in 6 of 6 rats, whereas methylphenidate did not. CONCLUSIONS: Unlike methylphenidate, physostigmine does not accelerate time to emergence from isoflurane anesthesia and does not restore righting during continuous isoflurane anesthesia. However, physostigmine consistently decreases BSP during deep isoflurane anesthesia, whereas methylphenidate does not. These findings suggest that activation of cholinergic neurotransmission during isoflurane anesthesia produces arousal states that are distinct from those induced by monoaminergic activation.National Institutes of Health (U.S.) (Grant TR01-GM104948)National Institutes of Health (U.S.) (Grant DP1-OD003646)National Institutes of Health (U.S.) (Grant K08-GM094394
Variations in right ventricular outflow tract morphology following repair of congenital heart disease: Implications for percutaneous pulmonary valve implantation
Objective: Our aim was to identify sub-groups of right ventricular outflow tract morphology that would be suitable for percutaneous pulmonary valve implantation and to document their prevalence in our patient population. Materials and Methods: Eighty-three consecutive patients with right ventricular outflow tract dysfunction (5-41 years, 76% tetralogy of Fallot) referred to our center for cardiovascular magnetic resonance were studied. A morphological classification was created according to visual assessment of three-dimensional reconstructions and detailed measurement. Diagnosis, right ventricular outflow tract type, surgical history and treatment outcomes were documented. Results: Right ventricular outflow tract morphology was heterogeneous; nevertheless, 5 patterns were visually identified. Type I, a pyramidal morphology, was most prevalent (49%) and related to the presence of a transannular patch. Other types (II-V) were seen more commonly in patients with conduits. Two patients had unclassifiable morphology. Ninety-five percent of patients were assigned to the correct morphological classification by visual assessment alone. Percutaneous pulmonary valve implantation was performed successfully in 10 patients with Type II-V morphology and in 1 patient with unclassifiable morphology. Percutaneous implantation was not performed in patients with Type I morphology. Only right ventricular outflow tract diameters 50% of outflow tract morphologies may be suitable for this approach, in particular with the development of new devices appropriate for larger outflow
Diurnal excretion of urinary cortisol, cortisone, and cortisol metabolites in chronic fatigue syndrome
Abstract Objective: The aim of this study was to obtain comprehensive information on basal hypothalamic-pituitary-adrenal (HPA) axis activity in chronic fatigue syndrome (CFS) patients who were not affected by medication or comorbid psychiatric disorder likely to influence the HPA axis. Method: Steroid analysis of urine collections from 0600 to 2100 h at 3-h intervals in CFS patients and in controls. Results: Urinary free cortisol and cortisone concentrations showed a significant normal diurnal rhythm, but levels were lower across the cycle in CFS. In contrast, while urinary cortisol metabolites also showed a normal diurnal rhythm, levels were not significantly different between the CFS and controls at any time. Derived metabolite ratios were similar in both groups. Conclusion: This study provides further evidence for reduced basal HPA axis function in patients with CFS, based on lower free cortisol and cortisone levels, but this is not corroborated by cortisol metabolite data. The difference between these measures cannot be explained by an altered timing of the diurnal rhythm.
Diurnal excretion of urinary cortisol, cortisone, and cortisol metabolites in chronic fatigue syndrome
Abstract Objective: The aim of this study was to obtain comprehensive information on basal hypothalamic-pituitary-adrenal (HPA) axis activity in chronic fatigue syndrome (CFS) patients who were not affected by medication or comorbid psychiatric disorder likely to influence the HPA axis. Method: Steroid analysis of urine collections from 0600 to 2100 h at 3-h intervals in CFS patients and in controls. Results: Urinary free cortisol and cortisone concentrations showed a significant normal diurnal rhythm, but levels were lower across the cycle in CFS. In contrast, while urinary cortisol metabolites also showed a normal diurnal rhythm, levels were not significantly different between the CFS and controls at any time. Derived metabolite ratios were similar in both groups. Conclusion: This study provides further evidence for reduced basal HPA axis function in patients with CFS, based on lower free cortisol and cortisone levels, but this is not corroborated by cortisol metabolite data. The difference between these measures cannot be explained by an altered timing of the diurnal rhythm.
Identification of bacteria associated with feline chronic gingivostomatitis using culture-dependent and culture-independent methods
Feline chronic gingivostomatitis (FCGS) is a chronic inflammatory disease of the oral cavity that causes severe pain and distress. There are currently no specific treatment methods available and little is known regarding its aetiology, although bacteria are thought to play a major role. The purpose of this study was to identify the oral bacterial flora in normal and diseased cats. Oral swabs were obtained from the palatoglossal folds of eight cats (three normal and five FCGS) and were subjected to microbiological culture. Pasteurella pneumotropica and Pasteurella multocida subsp. multocida were the most prevalent species identified by culture methods in the normal and FCGS samples, respectively. Bacteria were also identified using culture-independent methods (bacterial 16S rRNA gene sequencing). For the normal samples, 158 clones were analysed and 85 clones were sequenced. Capnocytophaga canimorsus (10.8% of clones analysed) was the predominant species. Uncultured species accounted for 8.2% of clones analysed, and 43.7% of clones analysed represented potentially novel species. For the FCGS samples, 253 clones were analysed and 91 clones were sequenced. The predominant species was P. multocida subsp. multocida (51.8% of clones analysed). Uncultured species accounted for 8.7% of clones analysed, and 4.7% of clones analysed represented potentially novel species. It is concluded that the oral flora in cats with FCGS appears to be less diverse than that found in normal cats. However, P. multocida subsp. multocida is found to be significantly more prevalent in FCGS than in normal cats and consequently may be of aetiological significance in this disease. (C) 2010 Elsevier B.V. All rights reserve
The XMM deep survey in the CDF-S II. a 9-20 keV selection of heavily obscured active galaxies at z>1.7
We present results on a search of heavily obscured active galaxies z>1.7
using the rest-frame 9-20 keV excess for X-ray sources detected in the deep
XMM-CDFS survey. Out of 176 sources selected with the conservative detection
criteria (>8 sigma) in the first source catalogue of Ranalli et al., 46 objects
lie in the redshift range of interest with the median redshift z~2.5. Their
typical rest-frame 10-20 keV luminosity is 1e+44 erg/s, as observed. Among
optically faint objects that lack spectroscopic redshift, four were found to be
strongly absorbed X-ray sources, and the enhanced Fe K emission or absorption
features in their X-ray spectra were used to obtain X-ray spectroscopic
redshifts. Using the X-ray colour-colour diagram based on the rest-frame 3-5
keV, 5-9 keV, and 9-20 keV bands, seven objects were selected for their 9-20
keV excess and were found to be strongly absorbed X-ray sources with column
density of nH > 0.6e+24 cm-2, including two possible Compton thick sources.
While they are emitting at quasar luminosity, ~3/4 of the sample objects are
found to be absorbed by nH > 1e+22 cm-2. A comparison with local AGN at the
matched luminosity suggests an increasing trend of the absorbed source fraction
for high-luminosity AGN towards high redshifts.Comment: 9 pages, 7 figures. Accepted for publication in A&
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