1,288 research outputs found

    Detection of a Super Star Cluster as the Ionizing Source in the Low Luminosity AGN NGC 4303

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    HST UV STIS imaging and spectroscopy of the low luminosity AGN (LLAGN) NGC 4303 have identified the previously detected UV-bright nucleus of this galaxy, as a compact, massive and luminous stellar cluster. The cluster with a size (FWHM) of 3.1 pc, and an ultraviolet luminosity log L (1500 A}(erg/s/A)= 38.33 is identified as a nuclear super star cluster (SSC) like those detected in the circumnuclear regions of spirals and starburst galaxies. The UV spectrum showing the characteristic broad P Cygni lines produced by the winds of massive young stars, is best fitted by the spectral energy distribution of a massive cluster of 1e5 Msol generated in an instantaneous burst 4 Myr ago. No evidence for an additional non-thermal ionizing source associated with an accreting black hole is detected in the ultraviolet. We hypothesize that at least some LLAGNs in spirals could be understood as the result of the combined ionizing radiation emitted by an evolving SSC and a black hole (BH) accreting with low radiative efficiency, coexisting in the inner few parsecs region.Comment: 4 figure

    Gravitational shocks as a key ingredient of Gamma-Ray Bursts

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    We identify a novel physical mechanism that may be responsible for energy release in γ\gamma-ray bursts. Radial perturbations in the neutron core, induced by its collision with collapsing outer layers during the early stages of supernova explosions, can trigger a gravitational shock, which can readily eject a small but significant fraction of the collapsing material at ultra-relativistic speeds. The development of such shocks is a strong-field effect arising in near-critical collapse in General Relativity and has been observed in numerical simulations in various contexts, including in particular radially perturbed neutron star collapse, albeit for a tiny range of initial conditions. Therefore, this effect can be easily missed in numerical simulations if the relevant parameter space is not exhaustively investigated. In the proposed picture, the observed rarity of γ\gamma-ray bursts would be explained if the relevant conditions for this mechanism appear in only about one in every 10410510^4-10^5 core collapse supernovae. We also mention the possibility that near-critical collapse could play a role in powering the central engines of Active Galactic Nuclei.Comment: 9 pages, 3 figure

    Cost-effectiveness analysis of tropisetron vs. chlorpromazine-dexamethasone in the control of acute emesis induced by highly emetogenic chemotherapy in children

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    To perform a cost-effectiveness analysis (CEA) between a standard antiemetic regimen-chlorpromazine + dexamethasone (CPM-DEX)- and a 5-HT3 receptor antagonist-tropisetron (TROP)--in the control of acute emesis induced by highly emetogenic chemotherapy in children, considering two analytic perspectives: hospital and patients. METHODS: The CEA was performed by constructing a decision tree, for both analytic perspectives, of the possible outcomes of treatment with TROP (single 0.2 mg/kg i.v.) or CPM (5-15 mg i.v. infusion for 3 doses) plus DEX (2 mg/m2 i.v. bolus i.v. x2). The patients were stratified by age in two groups (2-12 and 13-17). To estimate the probability of each endpoint at the decision tree we have taken as a base a trial developed in the Department of Pediatrics. Direct medical cost of primary therapy, failure, complications and side effects were included in the cost calculations. RESULTS: From patients' analytic perspective, TROP was more cost-effective than CPM-DEX for both groups of patients. Discrepancy between both analytic perspectives in 13-17 year-old patient's group was resolved in favour of the option chosen from the patients' analytic perspective (TROP). Sensitivity analysis showed the reliability of the results. CONCLUSIONS: 1. TROP was more cost-effective than CPM-DEX. 2. Taking into account the patients' analytic perspective is essential when we compare antiemetics pharmacoeconomically. 3. It seems necessary to increase the effectiveness of TROP in pediatric patients receiving highly emetogenic chemotherapy with strategies such as the addition of a steroid

    Recombinant Human Erythropoietin for the Treatment of Anemia in Children With Solid Malignant Tumors

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    Cancer is often associated with chronic anemia which frequently requires blood transfusions. This study was performed to assess the efficacy and safety of r-HuEPO therapy in children with cancer. PATIENTS AND METHODS: Twenty-five patients under 18 years of age with solid malignant tumors were treated with 150 U/kg/day of r-HuEPO 5 times weekly for 12 weeks. Response was defined as an increase of the baseline hemoglobin level by at least 2 g/dl. r-HuEPO patients were compared to 25 matched historical controls. RESULTS: Response was achieved in 72% of r-HuEPO patients. Hemoglobin level increased from 9.8 +/- 0.6 g/dl at baseline to 12.4 +/- 1.7 g/dl at the end of treatment in the r-HuEPO group and increased from 9.5 +/- 0.7 g/dl to 9.6 +/- 1.4 g/dl in the control group (P < .001, Student's t-test). Only 16% of patients receiving r-HuEPO required blood transfusions vs 96% of control patients (P < .001, Student's t-test), with mean units of blood transfused per patient being 0.35 in the r-HuEPO group and 3.56 in controls (P < .001, Student's t-test). There was a statistically significance improvement in Karnofsky's index in r-HuEPO patients. No adverse reaction related to r-HuEPO therapy was observed. CONCLUSIONS: r-HuEPO is a safe and effective means of increasing hemoglobin level and reducing blood requirements in children with solid malignant tumors receiving chemotherapy

    Document management practices in SMEs: An information management capability-based approach

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    Purpose: This research studied the current document management (DM) practices in small and medium-sized enterprises (SMEs) of a road freight transport sector in a South American city with the aim to determine strengths and challenges for improving information management. Design/methodology/approach: The study was conducted using a survey approach based on measuring information management capabilities (IMC) through the following main dimensions: perception about DM practices, DM policies and tools, IT usage, organizational climate, and problems related to document management. Findings: The main results from the work stated the challenges for these companies in adopting electronic document management systems (EDMS) and handling information effectively even though the business experience. Also, the study highlighted the top management commitment in terms of investments for IMC development. Nevertheless, this economic support tends to be not enough to afford the EDMS implementation. Originality/value: Regarding the importance of information in road freight transport sector, this paper explored DM practices in a field in which no previous studies related to DM had been conducted and set the basis to make decisions to improve information management performance

    Hospital volume and outcomes for acute pulmonary embolism: Multinational population based cohort study

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    [Objectives] To evaluate the association between experience in the management of acute pulmonary embolism, reflected by hospital case volume, and mortality.[Design] Multinational population based cohort study using data from the Registro Informatizado de la Enfermedad TromboEmbólica (RIETE) registry between 1 January 2001 and 31 August 2018.[Setting] 353 hospitals in 16 countries.[Participants] 39 257 consecutive patients with confirmed diagnosis of acute symptomatic pulmonary embolism.[Main] outcome measure Pulmonary embolism related mortality within 30 days after diagnosis of the condition.[Results] Patients with acute symptomatic pulmonary embolism admitted to high volume hospitals (>40 pulmonary embolisms per year) had a higher burden of comorbidities. A significant inverse association was seen between annual hospital volume and pulmonary embolism related mortality. Admission to hospitals in the highest quarter (that is, >40 pulmonary embolisms per year) was associated with a 44% reduction in the adjusted odds of pulmonary embolism related mortality at 30 days compared with admission to hospitals in the lowest quarter (<15 pulmonary embolisms per year; adjusted risk 1.3% v 2.3%; adjusted odds ratio 0.56 (95% confidence interval 0.33 to 0.95); P=0.03). Results were consistent in all sensitivity analyses. All cause mortality at 30 days was not significantly reduced between the two quarters (adjusted odds ratio 0.78 (0.50 to 1.22); P=0.28). Survivors showed little change in the odds of recurrent venous thromboembolism (odds ratio 0.76 (0.49 to 1.19)) or major bleeding (1.07 (0.77 to 1.47)) between the low and high volume hospitals.[Conclusions] In patients with acute symptomatic pulmonary embolism, admission to high volume hospitals was associated with significant reductions in adjusted pulmonary embolism related mortality at 30 days. These findings could have implications for management strategies.Peer reviewe

    Manual técnico: el cultivo de la yuca manihot esculenta crantz; para producción forrajera y su utilización en alimentación de bovinos

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    Análisis y conocimiento de los sistemas de producción ganaderos con el propósito de identificar y formular programas, planes y proyectos de Desarrollo tecnológico que permitan contribuir a mantener y mejorar la productividad, competitividad (viabilidad económica) , sostenibilidad agroecológica y la equidad social. Entre los factores que afectan principalmente la productividad de los sistemas de producción ganadera en Colombia y los países ubicados en la franja tropical, es la baja capacidad de sostenimiento animal por unidad de área, debido a la baja cantidad y calidad de las pasturas en diferentes épocas del año, principalmente en las épocas secas, Es en estas circunstancias es cuando se requiere tener o encontrar alternativas tecnológicas que permitan mantener las cantidades mínimas de forrajes requeridas para la alimentación de ganado. Con base en lo anterior, se propuso indagar e investigar sobre el potencial del cultivo de la yuca Manihot esculenta crantz como una alternativa importante para la producción forrajera, por el alto potencial de producción de biomasa de su parte aérea (en base fresca o base seca), y su alto valor nutricional pues sus hojas son ricas en proteínas, (entre 25-30%, de proteína, comparables con los de alfalfa y otras leguminosas forrajeras utilizadas en la alimentación de rumiantes.), carotenos, vitaminas B 1, B2, C y minerales

    Effective Knockdown of Gene Expression in Primary Microglia With siRNA and Magnetic Nanoparticles Without Cell Death or Inflammation.

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    Microglia, the resident immune cells of the brain, have multiple functions in physiological and pathological conditions, including Alzheimer's disease (AD). The use of primary microglial cell cultures has proved to be a valuable tool to study microglial biology under various conditions. However, more advanced transfection methodologies for primary cultured microglia are still needed, as current methodologies provide low transfection efficiency and induce cell death and/or inflammatory activation of the microglia. Here, we describe an easy, and effective method based on the Glial-Mag method (OZ Biosciences) using magnetic nanoparticles and a magnet to successfully transfect primary microglia cells with different small interfering RNAs (siRNAs). This method does not require specialist facilities or specific training and does not induce cell toxicity or inflammatory activation. We demonstrate that this protocol successfully decreases the expression of two key genes associated with AD, the triggering receptor expressed in myeloid cells 2 (TREM2) and CD33, in primary microglia cell cultures

    Associations between pedometer-determined physical activity and adiposity in children and adolescents: Systematic review

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    The present review sought to examine the recent evidence on associations between objectively physical activity determined by pedometer and adiposity. A search for observational studies was carried out using database Pubmed in May 2013. Of 278 potentially eligible papers, 34 papers were included. Most studies (28/34; 82%) were crosssectional and all used proxies for adiposity, such as body mass index (BMI) or BMI z-score as the outcome measure. Few studies (9%; 3/34) focused on pre-school children. There was consistent evidence of negative associations between pedometer-determined physical activity and adiposity: significant negative associations were observed in 24/34 (71%) of studies overall. The present review supports the hypothesis that higher levels of habitual physical activity are protective against child and adolescent obesity. However, prospective longitudinal studies are warranted; there is a need for more research on younger children, and for more ‘dose-response’ evidence

    Jóvenes, multitud y estallido social en Chile [Youth, multitudes and social upheaval in Chile]

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    El 18 de octubre de 2019, miles de jóvenes chilenos salieron a las calles para exigir una sociedad más justa, iniciando un proceso de cambio constitucional y de ciudadanía. Este artículo analiza ese proceso centrándose en las estrategias disruptivas de los y las jóvenes para impugnar los espacios públicos en los primeros meses de protesta. Con esta finalidad, se realizó una etnografía durante diez semanas -octubre a diciembre del 2019--, en las ciudades de Santiago y Valparaíso. Los resultados muestran que estos jóvenes se identifican como parte de una multitud que ha experimentado un despertar ciudadano, exigiendo mayor participación social. Se concluye que este despertar refleja las tendencias sociales de las juventudes de otras partes del mundo, que igualmente disputan y exigen transformaciones sociales en las democracias liberales
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