1,014 research outputs found

    The Generation of Fullerenes

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    We describe an efficient new algorithm for the generation of fullerenes. Our implementation of this algorithm is more than 3.5 times faster than the previously fastest generator for fullerenes -- fullgen -- and the first program since fullgen to be useful for more than 100 vertices. We also note a programming error in fullgen that caused problems for 136 or more vertices. We tabulate the numbers of fullerenes and IPR fullerenes up to 400 vertices. We also check up to 316 vertices a conjecture of Barnette that cubic planar graphs with maximum face size 6 are hamiltonian and verify that the smallest counterexample to the spiral conjecture has 380 vertices.Comment: 21 pages; added a not

    The C5a anaphylatoxin receptor CD88 is expressed in presynaptic terminals of hippocampal mossy fibres

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    Background: In the periphery, C5a acts through the G-protein coupled receptor CD88 to enhance/maintain inflammatory responses. In the brain, CD88 can be expressed on astrocytes, microglia and neurons. Previous studies have shown that the hippocampal CA3 region displays CD88-immunolabelling, and CD88 mRNA is present within dentate gyrus granule cells. As granule cells send dense axonal projections (mossy fibres) to CA3 pyramidal neurons, CD88 expression could be expressed on mossy fibres. However, the cellular location of CD88 within the hippocampal CA3 region is unknown

    Gastric cancer surgery: Billroth I or Billroth II for distal gastrectomy?

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    <p>Abstract</p> <p>Background</p> <p>The selection of an anastomosis method after a distal gastrectomy is a highly debatable topic; however, the available documentation lacks the necessary research based on a comparison of early postoperative complications. This study was conducted to investigate the difference of early postoperative complications between Billroth I and Billroth II types of anastomosis for distal gastrectomies.</p> <p>Methods</p> <p>A total of 809 patients who underwent distal gastrectomies for gastric cancer during four years were included in the study. The only study endpoint was analysis of in-patients' postoperative complications. The risk adjusted complication rate was compared by POSSUM (Physiological and operative severity score for enumeration of morbidity and mortality) and the severity of complications was compared by Rui Jin Hospital classification of complication.</p> <p>Results</p> <p>Complication rate of Billroth II type of anastomosis was almost double of that in Billroth I (P = 0.000). Similarly, the risk adjusted complication rate was also higher in Billroth II group. More severe complications were observed and the postoperative duration was significantly longer in Billroth II type (P = 0.000). Overall expenditure was significantly higher in Billroth II type (P = 0.000).</p> <p>Conclusion</p> <p>Billroth II method of anastomosis was associated with higher rate of early postoperative complications. Therefore, we conclude that the Billroth I method should be the first choice after a distal gastrectomy as long as the anatomic and oncological environment of an individual patient allows us to perform it. However more prospective studies should be designed to compare the overall surgical outcomes of both anastomosis methods.</p

    Effect of Ebola virus disease on maternal and child health services in Guinea: a retrospective observational cohort study

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    Background The 2014 west African epidemic of Ebola virus disease posed a major threat to the health systems of the countries affected. We sought to quantify the consequences of Ebola virus disease on maternal and child health services in the highly-affected Forest region of Guinea. Methods We did a retrospective, observational cohort study of women and children attending public health facilities for antenatal care, institutional delivery, and immunisation services in six of seven health districts in the Forest region (Beyla, Guéckédou, Kissidougou, Lola, Macenta, and N’Zérékoré). We examined monthly service use data for eight maternal and child health services indicators: antenatal care (≥1 antenatal care visit and ≥3 antenatal care visits), institutional delivery, and receipt of five infant vaccines: polio, pentavalent (diphtheria, tetanus, pertussis, hepatitis B virus, and Haemophilus influenzae type b), yellow fever, measles, and tuberculosis. We used interrupted time series models to estimate trends in each indicator across three time periods: pre-Ebola virus disease epidemic (January, 2013, to February, 2014), during-epidemic (March, 2014, to February, 2015) and postepidemic (March, 2015, to Feb, 2016). We used segmented ordinary least-squares (OLS) regression using Newey- West standard errors to accommodate for serial autocorrelation, and adjusted for any potential effect of birth seasonality on our outcomes. Findings In the months before the Ebola virus disease outbreak, all three maternal indicators showed a significantly positive change in trend, ranging from a monthly average increase of 61 (95% CI 38–84) institutional deliveries to 119 (95% CI 79–158) women achieving at least three antenatal care visits. These increasing trends were reversed during the epidemic: fewer institutional deliveries occurred (–240, 95% CI –293 to –187), and fewer women achieved at least one antenatal care visit (–418, 95% CI –535 to –300) or at least three antenatal care visits (–363, 95% CI –485 to –242) per month (p<0·0001 for all). Compared with the negative trend during the outbreak, the change in trend during the post-outbreak period showed that 173 more women per month (95% CI 51–294; p=0·0074) had at least one antenatal care visit, 257 more (95% CI 117–398; p=0·0010) had at least three antenatal care visits and 149 more (95% CI 91–206; p<0·0001) had institutional deliveries. However, although the numbers for these indicators increased in the post-epidemic period, the trends for all stagnated. Similarly, the increasing trend in child vaccination completion during the pre-epidemic period was followed by significant immediate and trend reductions across most vaccine types. Before the outbreak, the number of children younger than 12 months who had completed each vaccination ranged from 5752 (95% CI 2821–8682) for tuberculosis to 8043 (95% CI 7621–8464) for yellow fever. Immediately after the outbreak, significant reductions occurred in the level of all vaccinations except for yellow fever for which the reduction was marginal. The greatest reductions were noted for polio and tuberculosis at –3594 (95% CI –4811 to –2377; p<0·0001) and –3048 (95% CI –5879 to –216; p=0·0362) fewer vaccines administered, respectively. Compared with pre-Ebola virus disease outbreak trends, significant decreases occurred for all vaccines except polio, with the trend of monthly decreases in the number of children vaccinated ranging from –419 (95% CI –683 to –155; p=0·0034) fewer for BCG to –313 (95% CI–446 to –179; p<0·0001) fewer for pentavalent during the outbreak. In the post-Ebola virus disease outbreak period, vaccination coverage for polio, measles, and yellow fever continued to decrease, whereas the trend in coverage for tuberculosis and pentavalent did not significantly differ from zero. Interpretation Most maternal and child health indicators significantly declined during the Ebola virus disease outbreak in 2014. Despite a reduction in this negative trend in the post-outbreak period, the use of essential maternal and child health services have not recovered to their pre-outbreak levels, nor are they all on a course that suggests that they will recover without targeted interventions

    Ultraviolet radiation shapes seaweed communities

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    Genetic association study of QT interval highlights role for calcium signaling pathways in myocardial repolarization.

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    The QT interval, an electrocardiographic measure reflecting myocardial repolarization, is a heritable trait. QT prolongation is a risk factor for ventricular arrhythmias and sudden cardiac death (SCD) and could indicate the presence of the potentially lethal mendelian long-QT syndrome (LQTS). Using a genome-wide association and replication study in up to 100,000 individuals, we identified 35 common variant loci associated with QT interval that collectively explain ∼8-10% of QT-interval variation and highlight the importance of calcium regulation in myocardial repolarization. Rare variant analysis of 6 new QT interval-associated loci in 298 unrelated probands with LQTS identified coding variants not found in controls but of uncertain causality and therefore requiring validation. Several newly identified loci encode proteins that physically interact with other recognized repolarization proteins. Our integration of common variant association, expression and orthogonal protein-protein interaction screens provides new insights into cardiac electrophysiology and identifies new candidate genes for ventricular arrhythmias, LQTS and SCD

    Open Problems on Central Simple Algebras

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    We provide a survey of past research and a list of open problems regarding central simple algebras and the Brauer group over a field, intended both for experts and for beginners.Comment: v2 has some small revisions to the text. Some items are re-numbered, compared to v

    Diversity of sympathetic vasoconstrictor pathways and their plasticity after spinal cord injury

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    Sympathetic vasoconstrictor pathways pass through paravertebral ganglia carrying ongoing and reflex activity arising within the central nervous system to their vascular targets. The pattern of reflex activity is selective for particular vascular beds and appropriate for the physiological outcome (vasoconstriction or vasodilation). The preganglionic signals are distributed to most postganglionic neurones in ganglia via synapses that are always suprathreshold for action potential initiation (like skeletal neuromuscular junctions). Most postganglionic neurones receive only one of these “strong” inputs, other preganglionic connections being ineffective. Pre- and postganglionic neurones discharge normally at frequencies of 0.5–1 Hz and maximally in short bursts at <10 Hz. Animal experiments have revealed unexpected changes in these pathways following spinal cord injury. (1) After destruction of preganglionic neurones or axons, surviving terminals in ganglia sprout and rapidly re-establish strong connections, probably even to inappropriate postganglionic neurones. This could explain aberrant reflexes after spinal cord injury. (2) Cutaneous (tail) and splanchnic (mesenteric) arteries taken from below a spinal transection show dramatically enhanced responses in vitro to norepinephrine released from perivascular nerves. However the mechanisms that are modified differ between the two vessels, being mostly postjunctional in the tail artery and mostly prejunctional in the mesenteric artery. The changes are mimicked when postganglionic neurones are silenced by removal of their preganglionic input. Whether or not other arteries are also hyperresponsive to reflex activation, these observations suggest that the greatest contribution to raised peripheral resistance in autonomic dysreflexia follows the modifications of neurovascular transmission
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