1,250 research outputs found
Noble internal transport barriers and radial subdiffusion of toroidal magnetic lines
Single trajectories of magnetic line motion indicate the persistence of a
central protected plasma core, surrounded by a chaotic shell enclosed in a
double-sided transport barrier : the latter is identified as being composed of
two Cantori located on two successive "most-noble" numbers values of the
perturbed safety factor, and forming an internal transport barrier (ITB).
Magnetic lines which succeed to escape across this barrier begin to wander in a
wide chaotic sea extending up to a very robust barrier (as long as L<1) which
is identified mathematically as a robust KAM surface at the plasma edge. In
this case the motion is shown to be intermittent, with long stages of
pseudo-trapping in the chaotic shell, or of sticking around island remnants, as
expected for a continuous time random walk.Comment: TEX file, 84 pages including 32 color figures. Higher quality figures
can be seen on the PDF file at
http://membres.lycos.fr/fusionbfr/JHM/Tokamap/JSP.pd
Ascaroside Signaling Is Widely Conserved among Nematodes
Background: Nematodes are among the most successful animals on earth and include important human pathogens, yet little is known about nematode pheromone systems. A group of small molecules called ascarosides has been found to mediate mate finding, aggregation, and developmental diapause in Caenorhabditis elegans, but it is unknown whether ascaroside signaling exists outside of the genus Caenorhabditis.
Results: To determine whether ascarosides are used as signaling molecules by other nematode species, we performed a mass spectrometry-based screen for ascarosides in secretions from a variety of both free-living and parasitic (plant, insect, and animal) nematodes. We found that most of the species analyzed, including nematodes from several different clades, produce species-specific ascaroside mixtures. In some cases, ascaroside biosynthesis patterns appear to correlate with phylogeny, whereas in other cases, biosynthesis seems to correlate with lifestyle and ecological niche. We further show that ascarosides mediate distinct nematode behaviors, such as retention, avoidance, and long-range attraction, and that different nematode species respond to distinct, but overlapping, sets of ascarosides.
Conclusions: Our findings indicate that nematodes utilize a conserved family of signaling molecules despite having evolved to occupy diverse ecologies. Their structural features and level of conservation are evocative of bacterial quorum sensing, where acyl homoserine lactones (AHLs) are both produced and sensed by many species of gram-negative bacteria. The identification of species-specific ascaroside profiles may enable pheromone-based approaches to interfere with reproduction and survival of parasitic nematodes, which are responsible for significant agricultural losses and many human diseases worldwide
Fabrication of bipolar transistors by maskless ion implantation
The first focused ion beam (FIB) arsenic ion implants are reported. A shallow junction, vertical npn bipolar transistor fabricated by maskless implantation of B and As is described. For comparison, devices on the same wafer were also processed with conventional, broadâbeam B and/or As implants. Good transistor performance is obtained for each type of implanted transistor. Device characteristics for FIB and conventional implants are generally the same. However, initial results indicate that diode quality and junction leakage appear somewhat degraded (excess generationârecombination) for FIB arsenic implanted devices. Characteristics of FIB boron implanted devices obtained over an extended period have been measured. These data indicate that waferâtoâwafer dose uniformity and quality (diode ideality and leakage currents) is equal to that for conventional implants (standard deviation
An immunocompetent farmer with isolated cerebral alveolar echinococcosis: illustrative case
BACKGROUND: Alveolar echinococcosis is a rare condition, but living or working in a rural environment is a substantial risk factor. The liver is the organ primarily affected, with additional extrahepatic manifestations in approximately 25% of cases. Primary extrahepatic disease is rare, and isolated cerebral involvement is extremely unusual.
OBSERVATIONS: The authors described an illustrative case of isolated cerebral alveolar echinococcosis in an immunocompetent farmer. Magnetic resonance imaging of the brain showed a predominantly cystic lesion with perifocal edema and a âbunch of grapesâ appearance in the left frontal lobe. Histology revealed sharply demarcated fragments of a fibrous cyst wall accompanied by marked inflammation and necrosis. Higher magnification showed remnants of protoscolices with hooklets and calcified corpuscles. Immunohistochemistry and polymerase chain reaction (PCR) analysis confirmed the diagnosis of cerebral alveolar echinococcosis. Interestingly, serology and thoracic and abdominal computed tomography results were negative, indicative of an isolated primary extrahepatic manifestation.
LESSONS: Isolated, primary central nervous system echinococcosis is extremely rare, with only isolated case reports. As in the authorsâ case, it can occur in immunocompetent patients, especially persons with a rural vocational history. Negative serology results do not exclude cerebral echinococcosis, which requires histological confirmation. Immunohistochemical staining and PCR analysis are especially useful in cases without classic morphological findings
Pressure Dependence of the Elastic Moduli in Aluminum Rich Al-Li Compounds
I have carried out numerical first principles calculations of the pressure
dependence of the elastic moduli for several ordered structures in the
Aluminum-Lithium system, specifically FCC Al, FCC and BCC Li, L1_2 Al_3Li, and
an ordered FCC Al_7Li supercell. The calculations were performed using the full
potential linear augmented plane wave method (LAPW) to calculate the total
energy as a function of strain, after which the data was fit to a polynomial
function of the strain to determine the modulus. A procedure for estimating the
errors in this process is also given. The predicted equilibrium lattice
parameters are slightly smaller than found experimentally, consistent with
other LDA calculations. The computed elastic moduli are within approximately
10% of the experimentally measured moduli, provided the calculations are
carried out at the experimental lattice constant. The LDA equilibrium shear
modulus C11-C12 increases from 59.3 GPa in Al, to 76.0 GPa in Al_7Li, to 106.2
GPa in Al_3Li. The modulus C_44 increases from 38.4 GPa in Al to 46.1 GPa in
Al_7Li, then falls to 40.7 GPa in Al_3Li. All of the calculated elastic moduli
increase with pressure with the exception of BCC Li, which becomes elastically
unstable at about 2 GPa, where C_11-C_12 vanishes.Comment: 17 pages (REVTEX) + 7 postscript figure
Effects of Thresholding on Voxel-Wise Correspondence of Breath-Hold and Resting-State Maps of Cerebrovascular Reactivity
Functional magnetic resonance imaging for presurgical brain mapping enables neurosurgeons to identify viable tissue near a site of operable pathology which might be at risk of surgery-induced damage. However, focal brain pathology (e.g., tumors) may selectively disrupt neurovascular coupling while leaving the underlying neurons functionally intact. Such neurovascular uncoupling can result in false negatives on brain activation maps thereby compromising their use for surgical planning. One way to detect potential neurovascular uncoupling is to map cerebrovascular reactivity using either an active breath-hold challenge or a passive resting-state scan. The equivalence of these two methods has yet to be fully established, especially at a voxel level of resolution. To quantitatively compare breath-hold and resting-state maps of cerebrovascular reactivity, we first identified threshold settings that optimized coverage of gray matter while minimizing false responses in white matter. When so optimized, the resting-state metric had moderately better gray matter coverage and specificity. We then assessed the spatial correspondence between the two metrics within cortical gray matter, again, across a wide range of thresholds. Optimal spatial correspondence was strongly dependent on threshold settings which if improperly set tended to produce statistically biased maps. When optimized, the two CVR maps did have moderately good correspondence with each other (mean accuracy of 73.6%). Our results show that while the breath-hold and resting-state maps may appear qualitatively similar they are not quantitatively identical at a voxel level of resolution
Adaptation of an Evaluation System for e-Health Environments
Proceedings of: 14th International Conference, KES 2010, Cardiff, UK, September 8-10, 2010The increase in ageing of European population implies a high cost in economy and society in any European country and it can be reduced if we pay attention and develop home care systems. Evaluation of these systems is a critical and challenging issue but seldom tackled. It is important before evaluating a system to figure out what is the evaluation goal. In our case, such a goal is to evaluate enhanced user experience and beyond the evaluation goal it is also a central concern about what to evaluate. In this paper we propose a multi-agent home care system where we describe how agents coordinate their decisions to provide e-services to patients when at home after hospitalization. Finally we center our proposal on the adaptation of an evaluation system, previously developed, to support the challenges of an e-Health environment and also the multi-user evaluation. These evaluation methods (online/offline) will provide user's (patients, patient's relatives and healthcare professionals) feedback into the system.This work was supported in part by Projects CICYT TIN2008-06742-C02-02/
TSI, CICYT TEC2008-06732-C02-02/TEC, CAM CONTEXTS (S2009/
TIC-1485) and DPS2008-07029-C02-02.Publicad
Varicella vaccination coverage of children under two years of age in Germany
Background: Since July 2004, routine varicella vaccination is recommended by the German Standing Vaccination Committee in Germany. Health Insurance Funds started to cover vaccination costs at different time points between 2004 and 2006 in the Federal States. Nationwide representative data on vaccination coverage against varicella of children under two years of age are not available. We aimed to determine varicella vaccination coverage in statutory health insured children under two years of age in twelve German Federal States using data from associations of statutory health insurance physicians (ASHIPs), in order to investigate the acceptance of the recommended routine varicella vaccination programme. Methods: We analysed data on varicella vaccination from 13 of 17 ASHIPs of the years 2004 to 2007. The study population consisted of all statutory health insured children under two years of age born in 2004 (cohort 2004) or 2005 (cohort 2005) in one of the studied regions. Vaccination coverage was determined by the number of children vaccinated under 2 years of age within the study population. Results: Varicella vaccination coverage of children under two years of age with either one dose of the monovalent varicella vaccine or two doses of the measles, mumps, rubella, and varicella vaccine increased from 34% (cohort 2004) to 51% (cohort 2005) in the studied regions (p < 0.001). More than half of the vaccinated children of cohort 2004 and two third of cohort 2005 were immunised at the recommended age 11 to 14 months. The level of vaccination coverage of cohort 2004 was significantly associated with the delay in introduction of cost coverage since the recommendation of varicella vaccination (p < 0.001). Conclusions: Our study shows increasing varicella vaccination coverage of young children, indicating a growing acceptance of the routine varicella vaccination programme by the parents and physicians. We recommend further monitoring of vaccination coverage using data from ASHIPs to investigate acceptance of the routine vaccination programmes over time
Succinylated Octopamine Ascarosides and a New Pathway of Biogenic Amine Metabolism in Caenorhabditis elegans
The ascarosides, small-molecule signals derived from combinatorial
assembly of primary metabolism-derived building
blocks, play a central role in Caenorhabditis elegans biology and
regulate many aspects of development and behavior in this
model organism as well as in other nematodes. Using HPLCMS/
MS-based targeted metabolomics, we identified novel ascarosides
incorporating a side chain derived from succinylation of
the neurotransmitter octopamine. These compounds, named
osas#2, osas#9, and osas#10, are produced predominantly by L1
larvae, where they serve as part of a dispersal signal, whereas
these ascarosides are largely absent from the metabolomes of
other life stages. Investigating the biogenesis of these octopamine-
derived ascarosides, we found that succinylation represents
a previously unrecognized pathway of biogenic amine
metabolism. At physiological concentrations, the neurotransmitters
serotonin, dopamine, and octopamine are converted to a
large extent into the corresponding succinates, in addition to
the previously described acetates. Chemically, bimodal deactivation
of biogenic amines via acetylation and succinylation parallels
posttranslational modification of proteins via acetylation
and succinylation of L-lysine. Our results reveal a small-molecule
connection between neurotransmitter signaling and
interorganismal regulation of behavior and suggest that ascaroside
biosynthesis is based in part on co-option of degradative
biochemical pathways
Influenza vaccine effectiveness estimates in Europe in a season with three influenza type/subtypes circulating: the I-MOVE multicentre caseâcontrol study, influenza season 2012/13
In the fifth season of Influenza Monitoring Vaccine Effectiveness in Europe (I-MOVE), we undertook a multicentre caseâcontrol study (MCCS) in seven European Union (EU) Member States to measure 2012/13 influenza vaccine effectiveness against medically attended influenza-like illness (ILI) laboratory confirmed as influenza. The season was characterised by substantial co-circulation of influenza B, A(H1N1)pdm09 and A(H3N2) viruses. Practitioners systematically selected ILI patients to swab â€7 days of symptom onset. We compared influenza-positive by type/subtype to influenza-negative patients among those who met the EU ILI case definition. We conducted a complete case analysis using logistic regression with study as fixed effect and calculated adjusted vaccine effectiveness (AVE), controlling for potential confounders (age, sex, symptom onset week and presence of chronic conditions). We calculated AVE by type/subtype. Study sites sent 7,954 ILI/acute respiratory infection records for analysis. After applying exclusion criteria, we included 4,627 ILI patients in the analysis of VE against influenza B (1,937 cases), 3,516 for A(H1N1)pdm09 (1,068 cases) and 3,340 for influenza A(H3N2) (730 cases). AVE was 49.3% (95% confidence interval (CI): 32.4 to 62.0) against influenza B, 50.4% (95% CI: 28.4 to 65.6) against A(H1N1)pdm09 and 42.2% (95% CI: 14.9 to 60.7) against A(H3N2). Our results suggest an overall low to moderate AVE against influenza B, A(H1N1)pdm09 and A(H3N2), between 42 and 50%. In this season with many co-circulating viruses, the high sample size enabled stratified AVE by type/subtype. The low estimates indicate seasonal influenza vaccines should be improved to achieve acceptable protection levels
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