4,895 research outputs found

    First observation and measurement of the resonant structure of the lambda_b->lambda_c pi-pi+pi- decay mode

    Full text link
    We present the first observation of the lambda_b->lambda_c pi-pi+pi- decay using data from an integrated luminosity of approximately 2.4 fb-1 of ppbar collisions at ECM=1.96 TeV, collected with the CDF II detector at the Fermilab Tevatron. We also present the first observation of the resonant decays lambda_b->sigma_c(2455)0 pi+pi- ->lambda_c pi-pi+pi-, lambda_b->sigma_c(2455)++ pi-pi- ->lambda_c pi-pi+pi-, lambda_b->lambda_c(2595)+ pi- ->lambda_c pi-pi+pi- and lambda_b->lambda_c(2625)+ pi- ->lambda_c pi-pi+pi-, and measure their relative branching ratios.Comment: 3 pages, 3 figures, to appear in the proceedings of LEPTON PHOTON 2009, Hamburg, German

    Novel insights into the genetic relationship between growth and disease resistance in an aquaculture strain of Coho salmon (Oncorhynchus kisutch)

    Get PDF
    Breeding for disease resistance has become a highly desirable strategy for mitigating infectious disease problems in aquaculture. However, knowledge of the genetic relationship between resistance and other economically important traits, such as growth, is important to assess prior to including disease resistance into the breeding goal. Our study assessed the genetic correlations between growth and survival traits in a large bacterial infection challenge experiment. A population of 2606 coho salmon individuals from 107 full-sibling families were challenged with the bacteria Piscirickettsia salmonis. Growth was measured as average daily gain prior (ADG0) and during (ADGi) the experimental infection and as harvest weight (HW). Resistance was measured as Survival time (ST) and binary survival (BS). Furthermore, individual measures of bacterial load (BL) were assessed as new resistance phenotypes and to provide an indication of genetic variation in tolerance in salmonid species. Resistant families showed lower bacterial load than those susceptible to P. salmonis. Furthermore, some surviving fish belonging to resistant families, were considered as bacterial-free because their bacterial load was below the detection threshold. Adding logBL as a covariate into the models for growth under infection and survival indicated significant genetic variation in tolerance. Significant moderate heritabilities were estimated for ADG0 (0.30 ± 0.05), HW (0.38 ± 0.03), and for the survival traits ST (0.16 ± 0.03) and BS (0.18 ± 0.03). In contrast, heritabilities for ADGi and log-transformed BL were low (0.07 ± 0.02 (significant) and 0.04 ± 0.03, respectively), although these increased to moderate significant levels (0.20 ± 0.09 and 0.12 ± 0.05, respectively) when traits were assessed in survivors only. Significant favorable genetic correlations were found between ADG0 and ADGi (0.40 ± 0.16), HW (0.64 ± 0.09), and with resistance as ST (0.43 ± 0.18), indicating that fish with higher genetic growth rate early on and prior to infection not only tend to maintain their genetic growth advantage until harvest, but also tend to grow faster and survive longer during infection. Although a significant unfavorable correlation (−0.50 ± 0.13) between HW and ST was found, this value decreased to −0.35 ± 0.20 using uncensored data from non-survivors only. Similarly, no robust unfavorable genetic correlations between ADG0 and LogBL, or ADG0 and any of the other traits considered in this study, was identified. These results suggest that selective breeding for early growth, in the current coho salmon population, would be expected to simultaneously increase survival time and growth performance during an infection with Piscirickettsia salmonis, without negatively impacting on pathogen burden

    Genome-wide association and genomic selection in aquaculture

    Get PDF
    Recent advancements in genomic technologies have led to the discovery and application of DNA-markers [e.g. single nucleotide polymorphisms (SNPs)] for the genetic improvement of several aquaculture species. The identification of specific genomic regions associated with economically important traits, using, for example, genome-wide association studies (GWAS), has allowed the discovery and incorporation of markers linked to quantitative trait loci (QTL) into aquaculture breeding programs through marker-assisted selection (MAS). However, most of the traits of economic relevance are expected to be controlled by many QTLs, each one explaining only a small proportion of the genetic variation. For traits under polygenic control, prediction of the genetic merit of animals based on the sum of effects at positions across the entire genome (i.e. genomic estimated breeding values, GEBV, which are used for what has become known as genomic selection), has been demonstrated to speed the rate of genetic gain for several traits in aquaculture breeding. The aim of this review was to provide an overview of the development and application of genomic technologies in uncovering the genetic basis of complex traits and accelerating the genetic progress in aquaculture species, as well as providing future perspectives about the deployment of novel molecular technologies for selective breeding in coming years

    Complete larval development of the hermit crabs Clibanarius aequabilis and Clibanarius erythropus (Decapoda : Anomura : Diogenidae), under laboratory conditions, with a revision of the larval features of genus Clibanarius

    Get PDF
    The complete larval development (four zoeae and one megalopa) of Clibanarius aequabilis and C. erythropus, reared under laboratory conditions, is described and illustrated. The larval stages of the two northeastern Atlantic Clibanarius species cannot be easily differentiated. Their morphological characters are compared with those of other known Clibanarius larvae. The genus Clibanarius is very homogeneous with respect to larval characters. All Clibanarius zoeae display a broad and blunt rostrum, smooth abdominal segments and an antennal scale without a terminal spine. Beyond the second zoeal stage, the fourth telson process is present as a fused spine, and the uropods are biramous. In the fourth larval stage all species display a mandibular palp. The Clibanarius megalopa presents weakly developed or no ocular scales, symmetrical chelipeds, apically curved corneous dactylus in the second and third pereiopods, and 5-11 setae on the posterior margin of the telson. Apart from the number of zoeal stages, Clibanarius species may be separated, beyond the second zoeal stage, by the telson formula and the morphology of the fourth telson process.info:eu-repo/semantics/publishedVersio

    The NIKA2 instrument, a dual-band kilopixel KID array for millimetric astronomy

    Full text link
    NIKA2 (New IRAM KID Array 2) is a camera dedicated to millimeter wave astronomy based upon kilopixel arrays of Kinetic Inductance Detectors (KID). The pathfinder instrument, NIKA, has already shown state-of-the-art detector performance. NIKA2 builds upon this experience but goes one step further, increasing the total pixel count by a factor ∼\sim10 while maintaining the same per pixel performance. For the next decade, this camera will be the resident photometric instrument of the Institut de Radio Astronomie Millimetrique (IRAM) 30m telescope in Sierra Nevada (Spain). In this paper we give an overview of the main components of NIKA2, and describe the achieved detector performance. The camera has been permanently installed at the IRAM 30m telescope in October 2015. It will be made accessible to the scientific community at the end of 2016, after a one-year commissioning period. When this happens, NIKA2 will become a fundamental tool for astronomers worldwide.Comment: Proceedings of the 16th Low Temperature Detectors workshop. To be published in the Journal of Low Temperature Physics. 8 pages, 4 figures, 1 tabl

    The heart of Sakurai's Object revealed by ALMA

    Full text link
    We present high angular-resolution observations of Sakurai's object using the Atacama Large Millimeter Array, shedding new light on its morpho-kinematical structure. The millimetre continuum emission, observed at an angular resolution of 20 milliarcsec (corresponding to 70 AU), reveals a bright compact central component whose spectral index indicates that it composed of amorphous carbon dust. Based on these findings, we conclude that this emission traces the previously suggested dust disc observed in mid-infrared observations. Therefore, our observations provide the first direct imaging of such a disc. The H12^{12}CN(JJ=4→\rightarrow3) line emission, observed at an angular resolution of 300 milliarcsec (corresponding to 1000 AU), displays bipolar structure with a north-south velocity gradient. From the position-velocity diagram of this emission we identify the presence of an expanding disc and a bipolar molecular outflow. The inclination of the disc is determined to be ii=72∘^\circ. The derived values for the de-projected expansion velocity and the radius of the disc are vexpv_{\rm exp}=53 km s−1^{-1} and RR=277 AU, respectively. On the other hand, the de-projected expansion velocity of the bipolar outflow detected in the H12^{12}CN(JJ=4→\rightarrow3) emission of approximately 1000 km s−1^{-1}. We propose that the molecular outflow has an hourglass morphology with an opening angle of around 60∘^{\circ}. Our observations unambiguously show that an equatorial disc and bipolar outflows formed in Sakurai's object in less than 30 years after the born-again event occurred, providing important constraints for future modelling efforts of this phenomenon.Comment: 9 pages, 5 figures. Accepted for publication as a Letter in Astronomy and Astrophysic

    Distribution of macro- and micronutrient intakes in relation to the meal pattern of third- and fourth-grade schoolchilderen in the city of Quetzaltenango, Guatemala

    Get PDF
    Objective: Our objective was to assess the distribution of energy, macro- and micronutrient intakes by meal (breakfast, lunch, dinner and combined snacks) in a cross-sectional sample of schoolchildren. Design: Cross-sectional dietary survey in schoolchildren. Setting: Twelve private and public schools in the urban setting of Quetzaltenango, Guatemala. Subjects: A total of 449 schoolchildren (from higher and lower socio-economic strata) were enrolled in the study. Methods: Each child completed a single, pictorial 24 h prospective diary and a face-to-face interview to check completeness and estimate portion sizes. Estimated daily intakes were examined by mealtime as: (i) absolute intakes; (ii) relative nutrient distribution; and (iii) critical micronutrient density (i.e. nutrient density in relation to the WHO Recommended Nutrient Intakes/median age-specific Guatemalan energy requirements). Results: The daily distribution of energy intake was 24 % at breakfast, 30 % at lunch, 23 % at dinner and 23 % among snacks. Lunch was also the leading meal for macronutrients, providing 35 % of proteins, 27 % of fat and 30 % of carbohydrate. The distribution of selected micronutrients did not follow the pattern of energy, insofar as lunch provided relatively more vitamin C and Zn, whereas breakfast led in terms of vitamins A and D, thiamin, riboflavin, folate, Ca and Fe. Conclusions: Meal-specific distribution of energy, macro- and micronutrients provides a unique and little used perspective for evaluation of children's habitual intake, and may provide guidance to strategies to improve dietary balance in an era of coexisting energy overnutrition and micronutrient inadequacy. © The Authors 2008

    Performance of a Large-Area GEM Detector Prototype for the Upgrade of the CMS Muon Endcap System

    Full text link
    Gas Electron Multiplier (GEM) technology is being considered for the forward muon upgrade of the CMS experiment in Phase 2 of the CERN LHC. Its first implementation is planned for the GE1/1 system in the 1.5<∣η∣<2.21.5 < \mid\eta\mid < 2.2 region of the muon endcap mainly to control muon level-1 trigger rates after the second long LHC shutdown. A GE1/1 triple-GEM detector is read out by 3,072 radial strips with 455 μ\murad pitch arranged in eight η\eta-sectors. We assembled a full-size GE1/1 prototype of 1m length at Florida Tech and tested it in 20-120 GeV hadron beams at Fermilab using Ar/CO2_{2} 70:30 and the RD51 scalable readout system. Four small GEM detectors with 2-D readout and an average measured azimuthal resolution of 36 μ\murad provided precise reference tracks. Construction of this largest GEM detector built to-date is described. Strip cluster parameters, detection efficiency, and spatial resolution are studied with position and high voltage scans. The plateau detection efficiency is [97.1 ±\pm 0.2 (stat)]\%. The azimuthal resolution is found to be [123.5 ±\pm 1.6 (stat)] μ\murad when operating in the center of the efficiency plateau and using full pulse height information. The resolution can be slightly improved by ∼\sim 10 μ\murad when correcting for the bias due to discrete readout strips. The CMS upgrade design calls for readout electronics with binary hit output. When strip clusters are formed correspondingly without charge-weighting and with fixed hit thresholds, a position resolution of [136.8 ±\pm 2.5 stat] μ\murad is measured, consistent with the expected resolution of strip-pitch/12\sqrt{12} = 131.3 μ\murad. Other η\eta-sectors of the detector show similar response and performance.Comment: 8 pages, 32 figures, submitted to Proc. 2014 IEEE Nucl. Sci. Symposium, Seattle, WA, reference adde

    CAMKII Activation Is Not Required for Maintenance of Learning-Induced Enhancement of Neuronal Excitability

    Get PDF
    Pyramidal neurons in the piriform cortex from olfactory-discrimination trained rats show enhanced intrinsic neuronal excitability that lasts for several days after learning. Such enhanced intrinsic excitability is mediated by long-term reduction in the post-burst after-hyperpolarization (AHP) which is generated by repetitive spike firing. AHP reduction is due to decreased conductance of a calcium-dependent potassium current, the sIAHP. We have previously shown that learning-induced AHP reduction is maintained by persistent protein kinase C (PKC) and extracellular regulated kinase (ERK) activation. However, the molecular machinery underlying this long-lasting modulation of intrinsic excitability is yet to be fully described. Here we examine whether the CaMKII, which is known to be crucial in learning, memory and synaptic plasticity processes, is instrumental for the maintenance of learning-induced AHP reduction. KN93, that selectively blocks CaMKII autophosphorylation at Thr286, reduced the AHP in neurons from trained and control rat to the same extent. Consequently, the differences in AHP amplitude and neuronal adaptation between neurons from trained rats and controls remained. Accordingly, the level of activated CaMKII was similar in pirifrom cortex samples taken form trained and control rats. Our data show that although CaMKII modulates the amplitude of AHP of pyramidal neurons in the piriform cortex, its activation is not required for maintaining learning-induced enhancement of neuronal excitability

    DLGS97/SAP97 is developmentally upregulated and is required for complex adult behaviors and synapse morphology and function

    Get PDF
    The synaptic membrane-associated guanylate kinase (MAGUK) scaffolding protein family is thought to play key roles in synapse assembly and synaptic plasticity. Evidence supporting these roles in vivo is scarce, as a consequence of gene redundancy in mammals. The genome of Drosophila contains only one MAGUK gene, discs large (dlg), from which two major proteins originate: DLGA [PSD95 (postsynaptic density 95)-like] and DLGS97 [SAP97 (synapse-associated protein)-like]. These differ only by the inclusion in DLGS97 of an L27 domain, important for the formation of supramolecular assemblies. Known dlg mutations affect both forms and are lethal at larval stages attributable to tumoral overgrowth of epithelia. We generated independent null mutations for each, dlgA and dlgS97. These allowed unveiling of a shift in expression during the development of the nervous system: predominant expression of DLGA in the embryo, balanced expression of both during larval stages, and almost exclusive DLGS97 expression in the adult brain. Loss of embryonic DLGS97 does not alter the development of the nervous system. At larval stages, DLGA and DLGS97 fulfill both unique and partially redundant functions in the neuromuscular junction. Contrary to dlg and dlgA mutants, dlgS97 mutants are viable to adulthood, but they exhibit marked alterations in complex behaviors such as phototaxis, circadian activity, and courtship, whereas simpler behaviors like locomotion and odor and light perception are spared. We propose that the increased repertoire of associations of a synaptic scaffold protein given by an additional domain of protein-protein interaction underlies its ability to integrate molecular networks required for complex functions in adult synapses
    • …
    corecore