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Anesthetic action on the transmission delay between cortex and thalamus explains the beta-buzz observed under propofol anesthesia
In recent years, more and more surgeries under general anesthesia have been performed with the assistance of electroencephalogram (EEG) monitors. An increase in anesthetic concentration leads to characteristic changes in the power spectra of the EEG. Although tracking the anesthetic-induced changes in EEG rhythms can be employed to estimate the depth of anesthesia, their precise underlying mechanisms are still unknown. A prominent feature in the EEG of some patients is the emergence of a strong power peak in the ÎČâfrequency band, which moves to the αâfrequency band while increasing the anesthetic concentration. This feature is called the beta-buzz. In the present study, we use a thalamo-cortical neural population feedback model to reproduce observed characteristic features in frontal EEG power obtained experimentally during propofol general anesthesia, such as this beta-buzz. First, we find that the spectral power peak in the αâ and ÎŽâfrequency ranges depend on the decay rate constant of excitatory and inhibitory synapses, but the anesthetic action on synapses does not explain the beta-buzz. Moreover, considering the action of propofol on the transmission delay between cortex and thalamus, the model reveals that the beta-buzz may result from a prolongation of the transmission delay by increasing propofol concentration. A corresponding relationship between transmission delay and anesthetic blood concentration is derived. Finally, an analytical stability study demonstrates that increasing propofol concentration moves the systems resting state towards its stability threshold
Factors affecting exhaled nitric oxide measurements: the effect of sex
<p>Abstract</p> <p>Background</p> <p>Exhaled nitric oxide (F<sub>E</sub>NO) measurements are used as a surrogate marker for eosinophilic airway inflammation. However, many constitutional and environmental factors affect F<sub>E</sub>NO, making it difficult to devise reference values. Our aim was to evaluate the relative importance of factors affecting F<sub>E</sub>NO in a well characterised adult population.</p> <p>Methods</p> <p>Data were obtained from 895 members of the Dunedin Multidisciplinary Health and Development Study at age 32. The effects of sex, height, weight, lung function indices, smoking, atopy, asthma and rhinitis on F<sub>E</sub>NO were explored by unadjusted and adjusted linear regression analyses.</p> <p>Results</p> <p>The effect of sex on F<sub>E</sub>NO was both statistically and clinically significant, with F<sub>E</sub>NO levels approximately 25% less in females. Overall, current smoking reduced F<sub>E</sub>NO up to 50%, but this effect occurred predominantly in those who smoked on the day of the F<sub>E</sub>NO measurement. Atopy increased F<sub>E</sub>NO by 60%. The sex-related differences in F<sub>E</sub>NO remained significant (p < 0.001) after controlling for all other significant factors affecting F<sub>E</sub>NO.</p> <p>Conclusion</p> <p>Even after adjustment, F<sub>E</sub>NO values are significantly different in males and females. The derivation of reference values and the interpretation of F<sub>E</sub>NO in the clinical setting should be stratified by sex. Other common factors such as current smoking and atopy also require to be taken into account.</p
Reconstruction of major maternal and paternal lineages of the Cape Muslim population
The earliest Cape Muslims were brought to the Cape (Cape Town - South Africa) from Africa and Asia from 1652 to
1834. They were part of an involuntary migration of slaves, political prisoners and convicts, and they contributed to
the ethnic diversity of the present Cape Muslim population of South Africa. The history of the Cape Muslims has been
well documented and researched however no in-depth genetic studies have been undertaken. The aim of the present
study was to determine the respective African, Asian and European contributions to the mtDNA (maternal) and
Y-chromosomal (paternal) gene pool of the Cape Muslim population, by analyzing DNA samples of 100 unrelated
Muslim males born in the Cape Metropolitan area. A panel of six mtDNA and eight Y-chromosome SNP markers
were screened using polymerase chain reaction-restriction fragment length polymorphisms (PCR-RFLP). Overall
admixture estimates for the maternal line indicated Asian (0.4168) and African mtDNA (0.4005) as the main contributors.
The admixture estimates for the paternal line, however, showed a predominance of the Asian contribution
(0.7852). The findings are in accordance with historical data on the origins of the early Cape Muslims.Web of Scienc
Breastfeeding, Maternal Education and Cognitive Function: A Prospective Study in Twins
The effect of breastfeeding on cognitive abilities is examined in the offspring of highly educated women and compared to the effects in women with low or middle educational attainment. All offspring consisted of 12-year old mono- or dizygotic twins and this made it possible to study the effect of breastfeeding on mean cognition scores as well as the moderating effects of breastfeeding on the heritability of variation in cognition. Information on breastfeeding and cognitive ability was available for 6,569 children. Breastfeeding status was prospectively assessed in the first years after birth of the children. Maternal education is positively associated with performance on a standardized test for cognitive ability in offspring. A significant effect of breastfeeding on cognition was also observed. The effect was similar for offspring with mothers with a high, middle, and low educational level. Breast-fed children of highly educated mothers score on average 7.6 point higher on a standardized test of cognitive abilities (CITO test; range 500â550; effects size = .936) than formula-fed children of mothers with a low education. Individual differences in cognition scores are largely accounted for by additive genetic factors (80%) and breastfeeding does not modify the effect of genetic factors in any of the three strata of maternal education. Heritability was slightly lower in children with a mother with a middle-level education
Conformational Dynamics of Single pre-mRNA Molecules During \u3cem\u3eIn Vitro\u3c/em\u3e Splicing
The spliceosome is a complex small nuclear RNA (snRNA)-protein machine that removes introns from pre-mRNAs via two successive phosphoryl transfer reactions. The chemical steps are isoenergetic, yet splicing requires at least eight RNA-dependent ATPases responsible for substantial conformational rearrangements. To comprehensively monitor pre-mRNA conformational dynamics, we developed a strategy for single-molecule FRET (smFRET) that uses a small, efficiently spliced yeast pre-mRNA, Ubc4, in which donor and acceptor fluorophores are placed in the exons adjacent to the 5âČ and 3âČ splice sites. During splicing in vitro, we observed a multitude of generally reversible time-and ATP-dependent conformational transitions of individual pre-mRNAs. The conformational dynamics of branchpoint and 3âČ-splice site mutants differ from one another and from wild type. Because all transitions are reversible, spliceosome assembly appears to be occurring close to thermal equilibrium
Second law, entropy production, and reversibility in thermodynamics of information
We present a pedagogical review of the fundamental concepts in thermodynamics
of information, by focusing on the second law of thermodynamics and the entropy
production. Especially, we discuss the relationship among thermodynamic
reversibility, logical reversibility, and heat emission in the context of the
Landauer principle and clarify that these three concepts are fundamentally
distinct to each other. We also discuss thermodynamics of measurement and
feedback control by Maxwell's demon. We clarify that the demon and the second
law are indeed consistent in the measurement and the feedback processes
individually, by including the mutual information to the entropy production.Comment: 43 pages, 10 figures. As a chapter of: G. Snider et al. (eds.),
"Energy Limits in Computation: A Review of Landauer's Principle, Theory and
Experiments
Detection of Gamma-Ray Emission from the Starburst Galaxies M82 and NGC 253 with the Large Area Telescope on Fermi
We report the detection of high-energy gamma-ray emission from two starburst
galaxies using data obtained with the Large Area Telescope on board the Fermi
Gamma-ray Space Telescope. Steady point-like emission above 200 MeV has been
detected at significance levels of 6.8 sigma and 4.8 sigma respectively, from
sources positionally coincident with locations of the starburst galaxies M82
and NGC 253. The total fluxes of the sources are consistent with gamma-ray
emission originating from the interaction of cosmic rays with local
interstellar gas and radiation fields and constitute evidence for a link
between massive star formation and gamma-ray emission in star-forming galaxies.Comment: Submitted to ApJ Letter
Fermi Gamma-ray Imaging of a Radio Galaxy
The Fermi Gamma-ray Space Telescope has detected the gamma-ray glow emanating
from the giant radio lobes of the radio galaxy Centaurus A. The resolved
gamma-ray image shows the lobes clearly separated from the central active
source. In contrast to all other active galaxies detected so far in high-energy
gamma-rays, the lobe flux constitutes a considerable portion (>1/2) of the
total source emission. The gamma-ray emission from the lobes is interpreted as
inverse Compton scattered relic radiation from the cosmic microwave background
(CMB), with additional contribution at higher energies from the
infrared-to-optical extragalactic background light (EBL). These measurements
provide gamma-ray constraints on the magnetic field and particle energy content
in radio galaxy lobes, and a promising method to probe the cosmic relic photon
fields.Comment: 27 pages, includes Supplementary Online Material; corresponding
authors: C.C. Cheung, Y. Fukazawa, J. Knodlseder, L. Stawar
'Clinical triad' findings in pediatric Klippel-Feil patients
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