263 research outputs found

    The stellar and sub-stellar IMF of simple and composite populations

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    The current knowledge on the stellar IMF is documented. It appears to become top-heavy when the star-formation rate density surpasses about 0.1Msun/(yr pc^3) on a pc scale and it may become increasingly bottom-heavy with increasing metallicity and in increasingly massive early-type galaxies. It declines quite steeply below about 0.07Msun with brown dwarfs (BDs) and very low mass stars having their own IMF. The most massive star of mass mmax formed in an embedded cluster with stellar mass Mecl correlates strongly with Mecl being a result of gravitation-driven but resource-limited growth and fragmentation induced starvation. There is no convincing evidence whatsoever that massive stars do form in isolation. Various methods of discretising a stellar population are introduced: optimal sampling leads to a mass distribution that perfectly represents the exact form of the desired IMF and the mmax-to-Mecl relation, while random sampling results in statistical variations of the shape of the IMF. The observed mmax-to-Mecl correlation and the small spread of IMF power-law indices together suggest that optimally sampling the IMF may be the more realistic description of star formation than random sampling from a universal IMF with a constant upper mass limit. Composite populations on galaxy scales, which are formed from many pc scale star formation events, need to be described by the integrated galactic IMF. This IGIMF varies systematically from top-light to top-heavy in dependence of galaxy type and star formation rate, with dramatic implications for theories of galaxy formation and evolution.Comment: 167 pages, 37 figures, 3 tables, published in Stellar Systems and Galactic Structure, Vol.5, Springer. This revised version is consistent with the published version and includes additional references and minor additions to the text as well as a recomputed Table 1. ISBN 978-90-481-8817-

    Search for squarks and gluinos in events with isolated leptons, jets and missing transverse momentum at s√=8 TeV with the ATLAS detector

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    The results of a search for supersymmetry in final states containing at least one isolated lepton (electron or muon), jets and large missing transverse momentum with the ATLAS detector at the Large Hadron Collider are reported. The search is based on proton-proton collision data at a centre-of-mass energy s√=8 TeV collected in 2012, corresponding to an integrated luminosity of 20 fb−1. No significant excess above the Standard Model expectation is observed. Limits are set on supersymmetric particle masses for various supersymmetric models. Depending on the model, the search excludes gluino masses up to 1.32 TeV and squark masses up to 840 GeV. Limits are also set on the parameters of a minimal universal extra dimension model, excluding a compactification radius of 1/R c = 950 GeV for a cut-off scale times radius (ΛR c) of approximately 30

    Optimal deployment of components of cloud-hosted application for guaranteeing multitenancy isolation

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    One of the challenges of deploying multitenant cloud-hosted services that are designed to use (or be integrated with) several components is how to implement the required degree of isolation between the components when there is a change in the workload. Achieving the highest degree of isolation implies deploying a component exclusively for one tenant; which leads to high resource consumption and running cost per component. A low degree of isolation allows sharing of resources which could possibly reduce cost, but with known limitations of performance and security interference. This paper presents a model-based algorithm together with four variants of a metaheuristic that can be used with it, to provide near-optimal solutions for deploying components of a cloud-hosted application in a way that guarantees multitenancy isolation. When the workload changes, the model based algorithm solves an open multiclass QN model to determine the average number of requests that can access the components and then uses a metaheuristic to provide near-optimal solutions for deploying the components. Performance evaluation showed that the obtained solutions had low variability and percent deviation when compared to the reference/optimal solution. We also provide recommendations and best practice guidelines for deploying components in a way that guarantees the required degree of isolation

    Attenuation of doxorubicin-induced cardiotoxicity by mdivi-1: a mitochondrial division/mitophagy inhibitor

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    Doxorubicin is one of the most effective anti-cancer agents. However, its use is associated with adverse cardiac effects, including cardiomyopathy and progressive heart failure. Given the multiple beneficial effects of the mitochondrial division inhibitor (mdivi-1) in a variety of pathological conditions including heart failure and ischaemia and reperfusion injury, we investigated the effects of mdivi-1 on doxorubicin-induced cardiac dysfunction in naïve and stressed conditions using Langendorff perfused heart models and a model of oxidative stress was used to assess the effects of drug treatments on the mitochondrial depolarisation and hypercontracture of cardiac myocytes. Western blot analysis was used to measure the levels of p-Akt and p-Erk 1/2 and flow cytometry analysis was used to measure the levels p-Drp1 and p-p53 upon drug treatment. The HL60 leukaemia cell line was used to evaluate the effects of pharmacological inhibition of mitochondrial division on the cytotoxicity of doxorubicin in a cancer cell line. Doxorubicin caused a significant impairment of cardiac function and increased the infarct size to risk ratio in both naïve conditions and during ischaemia/reperfusion injury. Interestingly, co-treatment of doxorubicin with mdivi-1 attenuated these detrimental effects of doxorubicin. Doxorubicin also caused a reduction in the time taken to depolarisation and hypercontracture of cardiac myocytes, which were reversed with mdivi-1. Finally, doxorubicin caused a significant elevation in the levels of signalling proteins p-Akt, p-Erk 1/2, p-Drp1 and p-p53. Co-incubation of mdivi-1 with doxorubicin did not reduce the cytotoxicity of doxorubicin against HL-60 cells. These data suggest that the inhibition of mitochondrial fission protects the heart against doxorubicin-induced cardiac injury and identify mitochondrial fission as a new therapeutic target in ameliorating doxorubicin-induced cardiotoxicity without affecting its anti-cancer properties

    Impact of changes in cell multiplication stage during the preparation of sensitizing substance of red cells used in the serological diagnosis of leptospirosis.

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    Introducción: En Cuba desde 1981 se tiene implementada la hemoaglutinación indirecta como técnica diagnostica de Leptospirosis de forma alternativa en ausencia de otras que pueden ser más costosas pero efectivas en los diferentes estadios de la enfermedad. Para el desarrollo de la técnica se hace necesaria la sustancia sensibilizante de eritrocitos (SSE), asumiendo su producción el Instituto Finlay en el año 2009, a partir de una tecnología obsoleta en la etapa de multiplicación celular.Objetivo. El objetivo de este trabajo fue realizar cambios en esta etapa para obtener la SSE con los medios de cultivos disponibles en la planta de producción para el óptimo rendimiento del producto, sin afectar la actividad biológica como parámetro fundamental de calidad.Métodos. Fueron formados 8 grupos experimentales teniendo en cuenta: cepa productora (cepa LABIOFAM y cepa Finlay) medio de cultivo (MK y EMJH) y condiciones de cultivos (estático o agitado).Resultados y conclusión. Se obtuvo como resultado que la mejor variante fue en la que se utilizó la cepa de LABIOFAM, crecimiento en medio MEJH y agitado, con una disminución considerable en el tiempo de obtención de la SSE mediante esta nueva tecnología, con un título consistente con las exigencias de calidad. Permitiendo así comenzar los diferentes diseños de estudios de estabilidad y registro del producto.Introduction: In Cuba since 1981 has implemented the indirect hemagglutination as an alternative technique of Leptospirosis diagnosed, in the absence of others that may be more costly but effective at different stages of the disease. For the development of the technique requires the Erythrocytes Sensitize Substance (ESS), assuming the production Finlay Institute in 2009, from obsolete technology in the process of cell multiplication.Objective: The aim of this study was to make changes at this stage to obtain the ESS with the culture media available at the plant for optimum product performance, without affecting the biological activity as the basic parameter of quality.Methods: Eight experimental groups were formed according to multifactorial design, taking into account: production strain (LABIOFAM or Finlay strain of L. biflexa Patoc I), culture medium (MK and MEJH) and culture conditions (static or agitated).Results and conclusion: We obtained as a result that the best variant was the combination (LABIOFAM strain, growth in MEJH and agitated), with a considerable decrease in the time of the ESS obtaining by means of this new technology, with a consistent title with the demands of quality. This work allowed to use the best variant to begin the different designs of stability studies of the product

    Operation and performance of the ATLAS Tile Calorimeter in Run 1

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    The Tile Calorimeter is the hadron calorimeter covering the central region of the ATLAS experiment at the Large Hadron Collider. Approximately 10,000 photomultipliers collect light from scintillating tiles acting as the active material sandwiched between slabs of steel absorber. This paper gives an overview of the calorimeter’s performance during the years 2008–2012 using cosmic-ray muon events and proton–proton collision data at centre-of-mass energies of 7 and 8TeV with a total integrated luminosity of nearly 30 fb−1. The signal reconstruction methods, calibration systems as well as the detector operation status are presented. The energy and time calibration methods performed excellently, resulting in good stability of the calorimeter response under varying conditions during the LHC Run 1. Finally, the Tile Calorimeter response to isolated muons and hadrons as well as to jets from proton–proton collisions is presented. The results demonstrate excellent performance in accord with specifications mentioned in the Technical Design Report

    Multi-messenger observations of a binary neutron star merger

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    On 2017 August 17 a binary neutron star coalescence candidate (later designated GW170817) with merger time 12:41:04 UTC was observed through gravitational waves by the Advanced LIGO and Advanced Virgo detectors. The Fermi Gamma-ray Burst Monitor independently detected a gamma-ray burst (GRB 170817A) with a time delay of ~1.7 s with respect to the merger time. From the gravitational-wave signal, the source was initially localized to a sky region of 31 deg2 at a luminosity distance of 40+8-8 Mpc and with component masses consistent with neutron stars. The component masses were later measured to be in the range 0.86 to 2.26 Mo. An extensive observing campaign was launched across the electromagnetic spectrum leading to the discovery of a bright optical transient (SSS17a, now with the IAU identification of AT 2017gfo) in NGC 4993 (at ~40 Mpc) less than 11 hours after the merger by the One- Meter, Two Hemisphere (1M2H) team using the 1 m Swope Telescope. The optical transient was independently detected by multiple teams within an hour. Subsequent observations targeted the object and its environment. Early ultraviolet observations revealed a blue transient that faded within 48 hours. Optical and infrared observations showed a redward evolution over ~10 days. Following early non-detections, X-ray and radio emission were discovered at the transient’s position ~9 and ~16 days, respectively, after the merger. Both the X-ray and radio emission likely arise from a physical process that is distinct from the one that generates the UV/optical/near-infrared emission. No ultra-high-energy gamma-rays and no neutrino candidates consistent with the source were found in follow-up searches. These observations support the hypothesis that GW170817 was produced by the merger of two neutron stars in NGC4993 followed by a short gamma-ray burst (GRB 170817A) and a kilonova/macronova powered by the radioactive decay of r-process nuclei synthesized in the ejecta

    Search for supersymmetry in events with large missing transverse momentum, jets, and at least one tau lepton in 20 fb−1 of √s=8 TeV proton-proton collision data with the ATLAS detector

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    A search for supersymmetry (SUSY) in events with large missing transverse momentum, jets, at least one hadronically decaying tau lepton and zero or one additional light leptons (electron/muon), has been performed using 20.3fb−1 of proton-proton collision data at √s= 8 TeV recorded with the ATLAS detector at the Large Hadron Collider. No excess above the Standard Model background expectation is observed in the various signal regions and 95% confidence level upper limits on the visible cross section for new phenomena are set. The results of the analysis are interpreted in several SUSY scenarios, significantly extending previous limits obtained in the same final states. In the framework of minimal gauge-mediated SUSY breaking models, values of the SUSY breaking scale Λ below 63 TeV are excluded, independently of tan β. Exclusion limits are also derived for an mSUGRA/CMSSM model, in both the R-parity-conserving and R-parity-violating case. A further interpretation is presented in a framework of natural gauge mediation, in which the gluino is assumed to be the only light coloured sparticle and gluino masses below 1090 GeV are excluded

    Elaboração e validação de instrumento avaliador da adesão ao tratamento da hipertensão

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    OBJETIVO Elaborar e validar instrumento de avaliação da adesão ao tratamento da hipertensão arterial sistêmica, com base na teoria da resposta ao item. MÉTODOS O desenvolvimento do instrumento envolveu procedimentos teóricos, empíricos e analíticos. Os procedimentos teóricos compreenderam a definição do constructo adesão ao tratamento da hipertensão arterial sistêmica, identificação dos domínios intervenientes e a elaboração do instrumento, seguida da análise semântica e conceitual por peritos. O procedimento empírico englobou a aplicação do instrumento a 1.000 usuários com hipertensão arterial sistêmica, atendidos em um centro de referência em Fortaleza, CE, em 2012. A etapa analítica validou o instrumento por meio da análise psicométrica e dos procedimentos estatísticos. O modelo da teoria da resposta ao item usado na análise foi o da resposta gradual de Samejima. RESULTADOS Doze dos 23 itens do instrumento inicial foram calibrados e permaneceram na versão final. O coeficiente alfa (α) de Cronbach foi de 0,81. Os itens referentes ao uso da medicação quando apresenta algum sintoma e o uso de gordura apresentaram bom desempenho, pois tiveram melhor poder de discriminar os indivíduos que aderem ao tratamento. Deixar de tomar a medicação alguma vez e o consumo de carnes brancas apresentaram menor poder de discriminação. Itens referentes à realização de exercício físico e ser rotina seguir o tratamento não medicamentoso tiveram maior dificuldade de resposta. O instrumento mostrou-se mais apropriado para medir a baixa adesão ao tratamento da hipertensão arterial sistêmica do que a alta adesão. CONCLUSÕES O instrumento mostrou-se adequado para avaliar a adesão ao tratamento da hipertensão arterial sistêmica, pois consegue diferenciar os indivíduos com alta adesão daqueles com baixa adesão. Sua utilização pode facilitar a identificação e aferição do cumprimento à terapêutica prescrita, além de viabilizar o estabelecimento de metas a serem alcançadas

    Induction of androgenesis and production of haploid embryos in anther cultures of borage (Borago officinalis L.)

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    [EN] Borage (Borago officinalis L.) is an important medicinal plant with different culinary, pharmaceutical and industrial properties. Unfortunately, there are no published reports on the establishment of protocols to produce DHs in this species up to now. In this work, we show for the first time the induction of borage microspores to become embryogenic calli, from which haploid embryos are produced. In addition, we evaluated the effect of using different flower bud sizes, carbon sources, concentrations of 2,4-D and BAP, cold (4 A degrees C) pretreatments and heat shock treatments. Production of total calli, embryogenic calli and callus-derived embryos was differently affected by the different parameters studied. Our results showed that the use of 5-7 mm-long flower buds, a cold (4 A degrees C) pretreatment during 4 days, a 32 A degrees C heat shock for 3 days, and the addition of 3 % maltose and 2 mgl(-1) 2,4-D and 1 mgl(-1) BAP to the culture medium, was beneficial for embryo production. Overall, this work demonstrates that DH technology is possible in borage, and opens the door for future improvements needed to finally obtain borage DH plants.Eshaghi, ZC.; Abdollahi, MR.; Moosavi, SS.; Deljou, A.; Seguí-Simarro, JM. (2015). Induction of androgenesis and production of haploid embryos in anther cultures of borage (Borago officinalis L.). Plant Cell, Tissue and Organ Culture. 122:321-329. doi:10.1007/s11240-015-0768-5S321329122Abdollahi MR, Moieni A, Javaran MJ (2004) Interactive effects of shock and culture density on embryo induction in isolated microspore culture of Brassica napus L. cv. Global Iranian J Biotech 2:97–100Bohanec B, Neskovic M, Vujicic R (1993) Anther culture and androgenetic plant regeneration in buckwheat (Fagopyrum esculentum Moench). Plant Cell Tissue Organ Cult 35:259–266Calleberg E, Johansson L (1996) Effect of gelling agents on anther cultures. In: Jain SM, Sopory SK, Veilleux RE (eds) In vitro haploid production in higher plants, vol 23. Springer, Netherlands, pp 189–203Custers JBM, Cordewener JHG, Nöllen Y, Dons JJ, van Lookeren-Campagne MM (1994) Temperature controls both gametophytic and sporophytic development in microspore cultures of Brassica napus. Plant Cell Rep 13:267–271Ferrie AMR (2013) Advances in microspore culture technology: a biotechnological tool for the improvement of medicinal plants. In: Chandra S et al (eds) Biotechnology for medicinal plants. Springer, Berlin, pp 191–206Ferrie AMR, Caswell KL (2011) Isolated microspore culture techniques and recent progress for haploid and doubled haploid plant production. Plant Cell Tissue Organ Cult 104:301–309Ferrie AMR, Bethune T, Mykytyshyn M (2011) Microspore embryogenesis in the Apiaceae. Plant Cell Tissue Organ Cult 104:399–406Forster BP, Heberle-Bors E, Kasha KJ, Touraev A (2007) The resurgence of haploids in higher plants. Trends Plant Sci 12:368–375Gamborg OL, Miller RA, Ojiwa K (1968) Nutrient requirements of suspension culture of soybean root callus. Exp Cell Res 50:151–158Guil-Guerrero JL, García-Maroto F, Vilches-Ferrón MA, López-Alonso D (2003) Gamma-linolenic acid from fourteen Boraginaceae species. Ind Crop Prod 18:85–89Horrobin DF (1983) The regulation of prostaglandin biosynthesis by the manipulation of essential fatty acid metabolism. Rev Pure Appl Pharmacol Sci 4:339–383Irikova T, Grozeva S, Rodeva V (2011) Anther culture in pepper (Capsicum annuum L.) in vitro. Acta Physiol Plant 33:1559–1570Lauxen MS, Kaltchuk-Santos E, Hu CY, Callegari-Jacques SM, Bodanese-Zanettini MH (2003) Association between floral bud size and developmental stage in soybean microspores. Braz Arch Biol Technol 46:515–520Leach CR, Mayo O, Bürger R (1990) Quantitatively determined self-incompatibility. Outcrossing in Borago officinalis. Theoret Appl Genetics 79:427–430Lichter R (1982) Induction of haploid plants from isolated pollen of Brassica napus. Z Pflanzenphysiol 105:427–434Maluszynski M, Kasha KJ, Szarejko I (2003) Published doubled haploid protocols in plant species. In: Maluszynski M, Kasha KJ, Forster BP, Szarejko I (eds) Doubled haploid production in crop plants. A manual. Kluwer, Dordrecht, pp 309–335Maraschin SF, de Priester W, Spaink HP, Wang M (2005) Androgenic switch: an example of plant embryogenesis from the male gametophyte perspective. J Exp Bot 56:1711–1726McDonald BE, Fitzpatrick K (1998) Designer Vegetable Oils. In: Mazza G (ed) Functional foods, biochemical and processing aspects. Technomic Publ Co. Inc, Lancaster, pp 265–291Ozkum D, Tipirdamaz R (2002) The effects of cold treatment and charcoal on the in vitro androgenesis of pepper (Capsicum annuum L.). Turk J Bot 26:131–139Parra-Vega V, González-García B, Seguí-Simarro JM (2013a) Morphological markers to correlate bud and anther development with microsporogenesis and microgametogenesis in pepper (Capsicum annuum L.). Acta Physiol Plant 35:627–633Parra-Vega V, Renau-Morata B, Sifres A, Seguí-Simarro JM (2013b) Stress treatments and in vitro culture conditions influence microspore embryogenesis and growth of callus from anther walls of sweet pepper (Capsicum annuum L.). Plant Cell Tissue Organ Cult 112:353–360Raquin C (1983) Utilization of different sugars as carbon sources for in vitro cultures of Petuina. Z Pflanzenphysol 111:453–457Salas P, Rivas-Sendra A, Prohens J, Seguí-Simarro JM (2012) Influence of the stage for anther excision and heterostyly in embryogenesis induction from eggplant anther cultures. Euphytica 184:235–250Seguí-Simarro JM (2010) Androgenesis revisited. Bot Rev 76:377–404Seguí-Simarro JM, Nuez F (2006) Androgenesis induction from tomato anther cultures: callus characterization. Acta Hort 725:855–861Seguí-Simarro JM, Corral-Martínez P, Parra-Vega V, González-García B (2011) Androgenesis in recalcitrant solanaceous crops. Plant Cell Rep 30:765–778Shariatpanahi ME, Bal U, Heberle-Bors E, Touraev A (2006) Stresses applied for the reprogramming of plant microspores towards in vitro embryogenesis. Physiol Plant 127:519–534Simon JE, Chadwick AF, Craker LE (1984) Herbs: an indexed bibliography. 1971–1980. The scientific literature on selected herbs, and aromatic and medicinal plants of the temperate zone. Archon Books, Hamden, CTSkrzypek E, Czyczyło-Mysza I, Marcińska I, Wędzony M (2008) Prospects of androgenetic induction in Lupinus spp. Plant Cell Tissue Organ Cult 94(2):131–137Snape JW (1989) Doubled haploid breeding: theoretical basis and practical applications. In: Mujeeb-Kazi A, Sitch LA (eds) Review of advances in plant biotechnology, 1985–1988: 2nd international symposium genetic manipulation in crops. Mexico and Manila, CIMMYT and IRRI, pp 19–30Tipirdamaz R, Ellialtioğlu Ş (1998) The effects of cold treatments and activated charcoal on ABA contents of anthers and in vitro androgenesis in eggplant (Solanum melongena L.). In: Tsekos I, Moustakas M (eds) Progress in botanical research, Proceedings of the 1st Balkan botanical congress. Kluwer Academic Publishers, The NetherlandsVagera J, Havranek P (1985) In vitro induction of androgenesis in Capsicum annuum L. and its genetic aspests. Biol Plant 27(1):10–21Zur I, Dubas E, Golemiec E, Szechynska-Hebda M, Golebiowska G, Wedzony M (2009) Stress-related variation in antioxidative enzymes activity and cell metabolism efficiency associated with embryogenesis induction in isolated microspore culture of triticale (×Triticosecale Wittm.). Plant Cell Rep 28:1279–128
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