6,165 research outputs found
Measurements of the relative branching fractions of the decay channel including charmonium contributions
The study of the decay channel at LHCb offers great
opportunities to study different aspects of the Standard Model and possibly
Beyond Standard Model physics. In particular it can be interesting not only for
the possibility to measure CP asymmetry but also to study possible intermediate
resonances. The ratios of the branching fractions of the decay channel, of the charmless component with M_{p\bar p} <
2.85\unitm{GeV/}c^{2} and of the charmonium contribution relative
to the are presented.Comment: Presented at the 2011 Hadron Collider Physics symposium (HCP-2011),
Paris, France, November 14-18 2011, 3 pages, 4 figur
Analysis and correction of the magnetic field effects in the Hybrid Photo-Detectors of the RICH2 Ring Imaging Cherenkov detector of LHCb
The Ring Imaging Cherenkov detectors of the LHCb experiment at the Large
Hadron Collider at CERN are equipped with Hybrid Photo-Detectors. These vacuum
photo-detectors are affected by the stray magnetic field of the LHCb magnet,
which degrades their imaging properties. This effect increases the error on the
Cherenkov angle measurement and would reduce the particle identification
capabilities of LHCb. A system has been developed for the RICH2 Ring Imaging
Cherenkov detector to perform a detailed characterisation of the magnetic
distortion effects. It is described, along with the methods implemented to
correct for these effects, restoring the optimal resolution.Comment: 16 pages, 11 figure
The Future of RICH Detectors through the Light of the LHCb RICH
The limitations in performance of the present RICH system in the LHCb
experiment are given by the natural chromatic dispersion of the gaseous
Cherenkov radiator, the aberrations of the optical system and the pixel size of
the photon detectors. Moreover, the overall PID performance can be affected by
high detector occupancy as the pattern recognition becomes more difficult with
high particle multiplicities. This paper shows a way to improve performance by
systematically addressing each of the previously mentioned limitations. These
ideas are applied in the present and future upgrade phases of the LHCb
experiment. Although applied to specific circumstances, they are used as a
paradigm on what is achievable in the development and realisation of high
precision RICH detectors
From Protecting the Heart to Improving Athletic Performance - the Benefits of Local and Remote Ischaemic Preconditioning
Remote Ischemic Preconditioning (RIPC) is a non-invasive cardioprotective intervention that involves brief cycles of limb ischemia and reperfusion. This is typically delivered by inflating and deflating a blood pressure cuff on one or more limb(s) for several cycles, each inflation-deflation being 3-5 min in duration. RIPC has shown potential for protecting the heart and other organs from injury due to lethal ischemia and reperfusion injury, in a variety of clinical settings. The mechanisms underlying RIPC are under intense investigation but are just beginning to be deciphered. Emerging evidence suggests that RIPC has the potential to improve exercise performance, via both local and remote mechanisms. This review discusses the clinical studies that have investigated the role of RIPC in cardioprotection as well as those studying its applicability in improving athletic performance, while examining the potential mechanisms involved
Anthracycline-Induced Cardiotoxicity: Cardiac Monitoring by Continuous Wave-Doppler Ultrasound Cardiac Output Monitoring and Correlation to Echocardiography
Background: Anthracyclines are agents with a well-known cardiotoxicity. The study sought to evaluate the hemodynamic response to an anthracycline using real-time continuous-wave (CW)-Doppler ultrasound cardiac output monitoring (USCOM) and echocardiography in combination with serum biomarkers. Methods: 50 patients (26 male, 24 female, median age 59 years) suffering from various types of cancer received an anthracycline-based regimen. Patients' responses were measured at different time points (T0 prior to infusion, T1 6 h post infusion, T2 after 1 day, T3 after 7 days, and T4 after 3 months) with CW-Doppler ultrasound (T0-T4) and echocardiography (T1, T4) for hemodynamic parameters such as stroke volume (SV; SVUSCOM ml) and ejection fraction (EF; EFechocardiography%) and with NT-pro-BNP and hs-Troponin T (T0-T4). Results: During the 3-month observation period, the relative decrease in the EF determined by echocardiography was -2.1% (Delta T0-T4, T0 71 +/- 7.8%, T4 69.5 +/- 7%, p = 0.04), whereas the decrease in SV observed using CW-Doppler was -6.5% (Delta T0-T4, T0 54 +/- 19.2 ml, T4 50.5 +/- 20.6 ml, p = 0.14). The kinetics for serum biomarkers were inversely correlated. Conclusions: Combining real-time CW-Doppler USCOM and serum biomarkers is feasible for monitoring the immediate and chronic hemodynamic changes during an anthracycline-based regimen; the results obtained were comparable to those from echocardiography
Global Production Increased by Spatial Heterogeneity in a Population Dynamics Model
Spatial and temporal heterogeneity are often described as important factors having a strong impact on biodiversity. The effect of heterogeneity is in most cases analyzed by the response of biotic interactions such as competition of predation. It may also modify intrinsic population properties such as growth rate. Most of the studies are theoretic since it is often difficult to manipulate spatial heterogeneity in practice. Despite the large number of studies dealing with this topics, it is still difficult to understand how the heterogeneity affects populations dynamics. On the basis of a very simple model, this paper aims to explicitly provide a simple mechanism which can explain why spatial heterogeneity may be a favorable factor for production.We consider a two patch model and a logistic growth is assumed on each patch. A general condition on the migration rates and the local subpopulation growth rates is provided under which the total carrying capacity is higher than the sum of the local carrying capacities, which is not intuitive. As we illustrate, this result is robust under stochastic perturbations
Model of fibrolamellar hepatocellular carcinomas reveals striking enrichment in cancer stem cells
The aetiology of human fibrolamellar hepatocellular carcinomas (hFL-HCCs), cancers occurring increasingly in children to young adults, is poorly understood. We present a transplantable tumour line, maintained in immune-compromised mice, and validate it as a bona fide model of hFL-HCCs by multiple methods. RNA-seq analysis confirms the presence of a fusion transcript (DNAJB1-PRKACA) characteristic of hFL-HCC tumours. The hFL-HCC tumour line is highly enriched for cancer stem cells as indicated by limited dilution tumourigenicity assays, spheroid formation and flow cytometry. Immunohistochemistry on the hFL-HCC model, with parallel studies on 27 primary hFL-HCC tumours, provides robust evidence for expression of endodermal stem cell traits. Transcriptomic analyses of the tumour line and of multiple, normal hepatic lineage stages reveal a gene signature for hFL-HCCs closely resembling that of biliary tree stem cells-newly discovered precursors for liver and pancreas. This model offers unprecedented opportunities to investigate mechanisms underlying hFL-HCCs pathogenesis and potential therapies
How Does Restored Habitat For Chinook Salmon ( Oncorhynchus Tshawytscha ) In The Merced River In California Compare With Other Chinook Streams?
The amount of time and money spent on restoring rivers for declining populations of salmon has grown substantially in recent decades. But despite the infusion of resources, many studies suggest that salmon populations are continuing to decline, leading some to question the effectiveness of restoration efforts. Here we examine whether a particular form of salmon restoration—channel reconfiguration with gravel augmentation—generates physical and biological habitat that is comparable with other streams that support salmon. We compared a suite of habitat features known to influence the various life stages of Chinook salmon in a restoration project in California's Merced River with 19 other streams that also support Chinook that we surveyed in the same geographic region. Our survey showed that riffle habitats in the restored site of the Merced River have flow discharge and depth, substrate and food web characteristics that cannot be distinguished from other streams that support Chinook, suggesting that these factors are unlikely to be bottlenecks to salmon recovery in the Merced. However, compared with other streams in the region, the Merced has minimal riparian cover, fewer undercut banks, less woody debris and higher water temperatures, suggesting that these factors might limit salmon recovery. After identifying aspects in the Merced that differ from other streams, we used principal components analysis to correlate salmon densities to independent axes of environmental variation measured during our survey. These analyses suggested that salmon densities tend to be greatest in streams that have more undercut banks and woody debris and lower water temperatures. These are the same environmental factors that appear to be missing from the Merced River restoration effort. Collectively, our results narrow the set of candidate factors that may limit salmon recovery in channel reconfiguration restoration efforts. Copyright © 2012 John Wiley & Sons, Ltd.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/97512/1/rra1604.pd
Moon phase effect on mosquito vectors of West Nile virus in Madagascar: biodiversity, abundance, host attractiveness and feeding rates
West Nile Virus (WNV) infection occurs throughout Madagascar. Its epidemiological cycle involves horses, human, birds and mosquitoes. Our entomological data shows unexpected information on mosquitoes vectors diversity and biology that relates to the collection methods. This study highlights the effect of lunar cycle that has not been previously considered in previous studies in Madagascar. During 2017, the influence of the two lunar phases (full versus new moon) on mosquito populations was analyzed in a farm located in the surroundings of Antananarivo city, Madagascar. Each month, mosquito collections were performed twice: one night during the full moon and one during the new moon. Six light traps were used: three indoors (in horse's box stall, in a house, in a cowshed), while three outdoors (near a pigsty, near a chicken coop, near a water point). During 24 night catches, 36,448 specimens belonging to 23 species were collected with Culex antennatus (64%) and Cx. quinquefasciatus (30%) the most abundant species. Cx. antennatus was mostly collected in traps associated with domestic animals while Cx. quinquefasciatus in trap placed in house. Each month, the total number of females caught during new moon was 1 to 3,5 times higher than those caught during full moon (ANOVA; F=34.4, DF=3, P0,05) the same pattern than the abundance of mosquitoes collected in the farm. The lunar cycle has an effect on mosquito abundance and host attractiveness and might vary according to the mosquito species. This lunar effect and the location of traps should be taken into consideration for one target species during entomological investigations aiming at unraveling West-Nile virus transmission when using light traps
Diversity and community biomass depend on dispersal and disturbance in microalgal communities
The evidence for species diversity effects
on ecosystem functions is mainly based on studies not
explicitly addressing local or regional processes
regulating coexistence or the importance of community
structure in terms of species evenness. In experimental
communities of marine benthic microalgae,
we altered the successional stages and thus the strength
of local species interactions by manipulating rates of
dispersal and disturbance. The treatments altered
realized species richness, evenness and community
biomass. For species richness, dispersal mattered only
at high disturbance rates; when opening new space,
dispersal led to maximized richness at intermediate
dispersal rates. Evenness, in contrast, decreased with
dispersal at low or no disturbance, i.e. at late successional stages. Community biomass showed a nonlinear
hump-shaped response to increasing dispersal at
all disturbance levels.We found a positive correlation
between richness and biomass at early succession, and
a strong negative correlation between evenness and
biomass at late succession. In early succession both
community biomass and richness depend directly on
dispersal from the regional pool, whereas the late
successional pattern shows that if interactions allow
the most productive species to become dominant,
diverting resources from this species (i.e. higher
evenness) reduces production. Our study emphasizes
the difference in biodiversity–function relationships
over time, as different mechanisms contribute to the
regulation of richness and evenness in early and late
successional stages
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