116 research outputs found

    Fringe electric fields of flat and cylindrical deflectors inelectrostatic charged particle storage rings

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    Analytic expressions for the potentials and fields of flat and cylindrical plates, including the fringe fields, are given. The present analysis extends and simplifies the current expression for the fields of flat plates and develops expressions for the fringe fields of cylindrical plates in terms of polar coordinates. The development of a FORTRAN program to output the field strength at a given location within the Proton Electric Dipole Moment (Proton EDM) ring is then described. Fourth-order Runge-Kutta integration is used to investigate the effect of fringe fields on particle and spin dynamics with precision tracking in the proposed Proton EDM experiment.1331sciescopu

    The effect of salt-free - salt diet on the reproductive performance of Ile de France ewes

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    The aim of the present study was to establish the effect of salt-free - salt diet (SFSD) on the size of antral follicles during salt consumption, the duration of controlled breeding campaign and the ferti¬lities of ewes from the Ile de France breed. Тhe experiment was carried out with 57 ewes, which were divided into 3 groups (19 ewes in each) depending on whether they were subjected to SFSD and their contacts with rams during the first 8 days of the beginning of breeding: Group I – SFSD + ram con-tact; Group II – only SFSD; Group III – no SFSD, only ram contacts. The first day of the salt diet coincided with the first day of ram contacts. Transrectal ultrasound examinations of the ovaries were done on days 1, 2, 3, 5, 6 and 7. The time of manifestation of estrus (in days), pregnancy rate and fecundity were studied. A significant effect of time (P<0.05) and diet (P<0.01) on the size of follicles was established. The onset of the first estrus, the shortest terms of breeding campaign, the fertility and the fecundity results gave us reason to favour the scheme applied to Group II. A stimulatory effect of the diet in that study was demonstrated, but the pattern was different from our previous studies

    EffEct of brEEding sEason on thE kinEmatic paramEtErs and morphology of ram&apos; spErm from synthEtic population bulgarian milk shEEp brEEd

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    abstract AbADjievA, D., M. Chervenkov, r. StefAnov, n. MetoDiev, e. kiStAnovA, D. kAChevA and e. rAyChevA, 2014. effect of breeding season on the kinematic parameters and morphology of ram&apos; sperm from synthetic population bulgarian milk sheep breed. Bulg. J. Agric. Sci., the aim of this study was the investigation of the breeding season effect on the kinematic and main spermatological parameters of the rams from Synthetic Population Bulgarian Milk sheep breed (SPBM), new Bulgarian breed certificated in 2005. the experiment was carried out with seven rams. Two consecutive ejaculates from each ram were obtained by artificial vagina before and during the breeding campaign (n=28). overall sperm motility and the individual kinematic parameters of motile spermatozoa were assessed by the computer-aided sperm analysis system Sperm Class Analyzer (SCA). the sperm morphology was estimated after sperm blue stain and calculated as a percent of abnormal cells among 100 sperm cells from several fields on the slide. it was found that the ejaculates obtained from SPbM rams during the breeding season had better features of sperm motion kinetics. the values of the velocity parameters (P&lt; 0.05), motility (P&lt; 0.05), and percentages of spermatozoa with rapid (P&lt; 0.01) and medium (P&lt; 0.001) speed were higher than those from the ejaculates collected before the breeding season. Minor and not significant changes in the kinematic parameters of motile spermatozoa in consecutive ejaculates were observed. No significant differences were established in morphological status of spermatozoa in nonbreeding and breeding season. It seems that the better sperm motility kinematic parameters during the breeding season ensure the higher sperm fertility and success on the future insemination

    The mating-specific Gα interacts with a kinesin-14 and regulates pheromone-induced nuclear migration in budding yeast

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    As a budding yeast cell elongates toward its mating partner, cytoplasmic microtubules connect the nucleus to the cell cortex at the growth tip. The Kar3 kinesin-like motor protein is then thought to stimulate plus-end depolymerization of these microtubules, thus drawing the nucleus closer to the site where cell fusion and karyogamy will occur. Here, we show that pheromone stimulates a microtubule-independent interaction between Kar3 and the mating-specific Gα protein Gpa1 and that Gpa1 affects both microtubule orientation and cortical contact. The membrane localization of Gpa1 was found to polarize early in the mating response, at about the same time that the microtubules begin to attach to the incipient growth site. In the absence of Gpa1, microtubules lose contact with the cortex upon shrinking and Kar3 is improperly localized, suggesting that Gpa1 is a cortical anchor for Kar3. We infer that Gpa1 serves as a positional determinant for Kar3-bound microtubule plus ends during mating. © 2009 by The American Society for Cell Biology

    Proteome Profiling of Breast Tumors by Gel Electrophoresis and Nanoscale Electrospray Ionization Mass Spectrometry

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    We have conducted proteome-wide analysis of fresh surgery specimens derived from breast cancer patients, using an approach that integrates size-based intact protein fractionation, nanoscale liquid separation of peptides, electrospray ion trap mass spectrometry, and bioinformatics. Through this approach, we have acquired a large amount of peptide fragmentation spectra from size-resolved fractions of the proteomes of several breast tumors, tissue peripheral to the tumor, and samples from patients undergoing noncancer surgery. Label-free quantitation was used to generate protein abundance maps for each proteome and perform comparative analyses. The mass spectrometry data revealed distinct qualitative and quantitative patterns distinguishing the tumors from healthy tissue as well as differences between metastatic and non-metastatic human breast cancers including many established and potential novel candidate protein biomarkers. Selected proteins were evaluated by Western blotting using tumors grouped according to histological grade, size, and receptor expression but differing in nodal status. Immunohistochemical analysis of a wide panel of breast tumors was conducted to assess expression in different types of breast cancers and the cellular distribution of the candidate proteins. These experiments provided further insights and an independent validation of the data obtained by mass spectrometry and revealed the potential of this approach for establishing multimodal markers for early metastasis, therapy outcomes, prognosis, and diagnosis in the future. © 2008 American Chemical Society

    The Machine Learning Landscape of Top Taggers

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    Based on the established task of identifying boosted, hadronically decaying top quarks, we compare a wide range of modern machine learning approaches. Unlike most established methods they rely on low-level input, for instance calorimeter output. While their network architectures are vastly different, their performance is comparatively similar. In general, we find that these new approaches are extremely powerful and great fun.Comment: Yet another tagger included

    Gβ promotes pheromone receptor polarization and yeast chemotropism by inhibiting receptor phosphorylation

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    Gradient-directed cell migration (chemotaxis) and growth (chemotropism) are processes that are essential to the development and life cycles of all species. Cells use surface receptors to sense the shallow chemical gradients that elicit chemotaxis and chemotropism. Slight asymmetries in receptor activation are amplified by downstream signaling systems, which ultimately induce dynamic reorganization of the cytoskeleton. During the mating response of budding yeast, a model chemotropic system, the pheromone receptors on the plasma membrane polarize to the side of the cell closest to the stimulus. Although receptor polarization occurs before and independently of actin cable-dependent delivery of vesicles to the plasma membrane (directed secretion), it requires receptor internalization. Phosphorylation of pheromone receptors by yeast casein kinase 1 or 2 (Yck1/2) stimulates their internalization. We showed that the pheromone-responsive G?? dimer promotes the polarization of the pheromone receptor by interacting with Yck1/2 and locally inhibiting receptor phosphorylation. We also found that receptor phosphorylation is essential for chemotropism, independently of its role in inducing receptor internalization. A mathematical model supports the idea that the interaction between G?? and Yck1/2 results in differential phosphorylation and internalization of the pheromone receptor and accounts for its polarization before the initiation of directed secretion

    Tmetoceratidae (Ammonitina) fauna from the Gerecse Mts (Hungary)

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    Abstract Taxonomic and stratigraphic problems of the family Tmetoceratidae and the genera Dumortieria, Catulloceras, Cotteswoldia, Pleydellia and Tmetoceras included in it are briefly discussed. Fifteen species of Tmetoceratidae are described and illustrated from the Upper Toarcian-Aalenian ammonite assemblages of the Gerecse Mts (NE Transdanubian Range, Hungary). The fauna described here is closely allied to the Mediterranean Province of the Mediterranean-Caucasian Realm

    The mechanism of formation, structure and physiological relevance of covalent hemoglobin attachment to the erythrocyte membrane

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    Covalent hemoglobin binding to membranes leads to band 3 (AE1) clustering and the removal of erythrocytes from the circulation; it is also implicated in blood storage lesions. Damaged hemoglobin, with the heme being in a redox and oxygen-binding inactive hemichrome form, has been implicated as the binding species. However, previous studies used strong non-physiological oxidants. In vivo hemoglobin is constantly being oxidised to methemoglobin (ferric), with around 1% of hemoglobin being in this form at any one time. In this study we tested the ability of the natural oxidised form of hemoglobin (methemoglobin) in the presence or absence of the physiological oxidant hydrogen peroxide to initiate membrane binding. The higher the oxidation state of hemoglobin (from Fe(III) to Fe(V)) the more binding was observed, with approximately 50% of this binding requiring reactive sulphydryl groups. The hemoglobin bound was in a high molecular weight complex containing spectrin, ankyrin and band 4.2, which are common to one of the cytoskeletal nodes. Unusually, we showed that hemoglobin bound in this way was redox active and capable of ligand binding. It can initiate lipid peroxidation showing the potential to cause cell damage. In vivo oxidative stress studies using extreme endurance exercise challenges showed an increase in hemoglobin membrane binding, especially in older cells with lower levels of antioxidant enzymes. These are then targeted for destruction. We propose a model where mild oxidative stress initiates the binding of redox active hemoglobin to the membrane. The maximum lifetime of the erythrocyte is thus governed by the redox activity of the cell; from the moment of its release into the circulation the timer is set
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