271 research outputs found

    A white dwarf-neutron star relativistic binary model for soft gamma-ray repeaters

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    A scenario for SGRs is introduced in which gravitational radiation reaction effects drive the dynamics of an ultrashort orbital period X-ray binary embracing a high-mass donor white dwarf (WD) to a rapidly rotating low magnetised massive neutron star (NS) surrounded by a thick, dense and massive accretion torus. Driven by GR reaction, sparsely, the binary separation reduces, the WD overflows its Roche lobe and the mass transfer drives unstable the accretion disk around the NS. As the binary circular orbital period is a multiple integer number (mm) of the period of the WD fundamental mode (Pons et al. 2002), the WD is since long pulsating at its fundamental mode; and most of its harmonics, due to the tidal interaction with its NS orbital companion. Hence, when the powerful irradiation glows onto the WD; from the fireball ejected as part of the disk matter slumps onto the NS, it is partially absorbed. This huge energy excites other WD radial (pp-mode) pulsations (Podsiadlowski 1991,1995). After each mass-transfer episode the binary separation (and orbital period) is augmented significantly (Deloye & Bildsten 2003; Al\'ecyan & Morsink 2004) due to the binary's angular momentum redistribution. Thus a new adiabatic inspiral phase driven by GR reaction starts which brings the binary close again, and the process repeats. This model allows to explain most of SGRs observational features: their recurrent activity, energetics of giant superoutbursts and quiescent stages, and particularly the intriguing subpulses discovered by BeppoSAX (Feroci et al. 1999), which are suggested here to be {\it overtones} of the WD radial fundamental mode (see the accompanying paper: Mosquera Cuesta 2004b).Comment: This paper was submitted as a "Letter to the Editor" of MNRAS in July 17/2004. Since that time no answer or referee report was provided to the Author [MNRAS publication policy limits reviewal process no longer than one month (+/- half more) for the reviewal of this kind of submission). I hope this contribution is not receiving a similar "peer-reviewing" as given to the A. Dar and A. De Rujula's "Cannonball model for gamma-ray bursts", or to the R.K. Williams' "Penrose process for energy extraction from rotating black holes". The author welcomes criticisms and suggestions on this pape

    Evaluación de los niveles de remoción en demanda química y bioquímica de oxígeno y sólidos suspendidos totales de efluentes industriales con bacterias productoras de polihidroxialcanoatos y exopolisacáridos a escala de laboratorio en empresas del sector de alimentos de la ciudad de Manizales

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    Maestría en Desarrollo Sostenible y Medio Ambiente, Facultad de Ciencias Contables, Económicas y Administrativas.Los efluentes industriales son fuente de contaminación en los cuerpos de agua; pueden ser tratados con microorganismos especializados que transforman este sustrato en subproductos de uso industrial, y a su vez disminuyen la carga contaminante. Las bacterias pueden producir diferentes compuestos, entre ellos los polihidroxialcanoatos (PHA) y Exopolisacáridos (EPS), aprovechando esta propiedad se evaluaron los niveles de remoción en demanda química y bioquímica de oxígeno, y sólidos suspendidos totales de efluentes industriales de dos empresas del sector alimenticio de la ciudad de Manizales, mediante la utilización de reactores aerobios tipo batch, inoculados con bacterias que presentaron mayor producción de EPS y PHA en medio sintético, a las cuales se les realizó cinética de crecimiento, registrando la variación de pH, con el fin de tener un punto de referencia en el sustrato objeto de estudio. Se obtuvo remociones hasta del 99,07% en S.S.T., 99,17% en DBO5 y 85,93% en DQO, alcanzando producciones de 1667 mg/L de PHA y de 6483 mg/L de EPS.Centro para la Formación Cafetera - SENA Regional Caldas. Tecnoparque - Nodo Manizales -SENA Regional Calada

    Mandibular angle augmentation using customized PEEK implants and guides generated with 3D Planning and Printing: case estudies

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    Mandibular angle augmentation is a procedure that, despite its obvious aesthetic and reconstructive indications, is not routinely performed, even by experienced surgeons. We present a case series of 10 patients treated with custom-made mandibular or inferior border prostheses for aesthetic concerns and sequelae following trauma or orthognathic surgery. Customized implants were designed with CAD/CAM technology, milled from Polyetheretherketone (PEEK) and 3D-printed implant placement guides were used. Ten patients (6 men and 4 women) were included; median age was 36.5 years (28-45 years). Indications for surgery were aesthetics (5 cases) and postoperative sequelae (4 orthognathic surgery and 1 mentoplasty). No significant early complications occurred, except edema and small bruises. Three patients developed wound dehiscence and prosthesis exposure, which closed spontaneously after 2-3 weeks, except one case that required a slight reduction of the upper edge of the prosthesis. No prostheses required removal. After the initial healing period there were no exposures or any late-onset infections or prosthesis intolerance. The use of customized PEEK prostheses together with tooth-supported guides provides treatment that is safe, easier surgically and more reliable. More experience is needed to define bone beauty standards to achieve the desired aesthetic result

    Trends in tropical forest loss and the social value of emission reductions

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    Reducing global forest losses is essential to mitigate climate change and its associated social costs. Multiple market and non-market factors can enhance or reduce forest loss. Here, to understand the role of non-market factors (for example, policies, climate anomalies or conflicts), we can compare observed trends to a reference (expected) scenario that excludes non-market factors. We define an expected scenario by simulating land-use decisions solely driven by market prices, productivities and presumably plausible decision-making. The land-use allocation model considers economic profits and uncertainties as incentives for forest conversion. We compare reference forest losses in Brazil, the Democratic Republic of Congo and Indonesia (2000–2019) with observed forest losses and assign differences from non-market factors. Our results suggest that non-market factors temporarily lead to lower-than-expected forest losses summing to 11.1 million hectares, but also to phases with higher-than-expected forest losses of 11.3 million hectares. Phases with lower-than-expected forest losses occurred earlier than those with higher-than-expected forest losses. The damages avoided by delaying emissions that would otherwise have occurred represent a social value of US$61.6 billion (as of the year 2000). This result shows the economic importance of forest conservation efforts in the tropics, even if reduced forest loss might be temporary and reverse over time

    Biodiversidad y servicios ecosistémicos del relicto de bosque SENA Regional Caldas

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    El libro reúne información de la flora y fauna del relicto de bosque del SENA Regional Caldas, contiene anotaciones y fotografías que sirven como guía para el reconocimiento de las especies y establece los servicios ecosistémicos que se proporcionan a la comunidad.The book collects information on the flora and fauna of the forest relict of SENA Regional Caldas, contains annotations and photographs that serve as a guide for the recognition of the species and establishes the ecosystem services that are provided to the community.Flora -- Los artrópodos -- Las aves -- Mamíferos terrestres y voladores Calidad de aguana181 página

    APROVECHAMIENTO DE SEMILLA DE MANGO EN EL DESARROLLO DE GALLETAS PARA CONSUMO HUMANO

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    Mango seed is a waste in companies which produce concentrates and juices. Most of the time it is always discarded to landfills or used tofeed animals. It is composed by two main parts, cotyledon and endocarp, the first one is used for food and comestic industry. The main objectiveof this paper is taking advantage of mango cotyledon flour to produce a food product made in Centro para la Formación Cafetera at RegionalCaldas SENA. Seed preparation procedure: Seed washing, drying, endocarp separation through guillotine, grinding and drying at controlled temperature. Afterwards, all material must be packed and refrigerated. Oil and flour separation was evaluated by extraction methods such as endless screw and Soxhlet method. Food prototype design was determined by raw materials percentages that will form the cookie dough. Then, dough was baken to make food sensorials and bromatological analysis according to current legal regulations, as a result, dough with some parts of mango cotyledon keeps a higher moisture retention, sandy textures and chocolate notes in the final product than other ones without it. Those doughs do not form gel, avoid to increasing their viscosity and have a low moisture and AW, resulting in a greater probability of useful life. Finally, mango cotyledon can contribute to shelf life of cookie products when diminishing free water quantity in food .La semilla de mango es un residuo de las empresas productoras de concentrados y jugos, ella generalmente es desechada en rellenossanitarios o es utilizada en alimentación de animales como consumo directo. La semilla de mango tiene dos partes principales, el cotiledóny el endocarpio, en el caso del cotiledón, puede ser aprovechado en la industria de alimentos y cosmética; es así como el objetivo del presentetrabajo consiste en aprovechar la harina de cotiledón de mango en la formulación de un producto alimenticio elaborado en el Centropara la Formación Cafetera del SENA regional Caldas. El procedimiento de preparación de la semilla fue: Lavado de semillas, secado,separación de endocarpio a través de guillotina, molienda y secado a temperatura controlada, posteriormente empacado y conservación enrefrigeración. Se evaluó la separación del aceite y la harina mediante métodos de extracción como compresión por tornillo sin fin y métodoSoxhlet. Para el diseño del prototipo alimenticio se determinaron los porcentajes de materias primas que formarían la masa galletera. Luego,se horneó la masa y se procedió a realizar análisis sensoriales y bromatológicos de alimentos, de acuerdo a parámetros de normativa legal vigente, encontrando que las masas trabajadas con harinas de cotiledón de mango presentan mayor retención de humedad, texturas arenosas y notas achocolatadas en el producto final; estas masas no forman gel, no incrementan su viscosidad y poseen menor cantidad de humedad, así como menor aw, dando como resultado una mayor estimación de vida útil; con lo cual las harinas de cotiledón de mango pueden contribuir con el incremento de la vida de anaquel de productos de galletería, al disminuir la cantidad de agua libre, presente en este tipo de alimentos

    Cytokinin response factors regulate PIN-FORMED auxin transporters

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    Auxin and cytokinin are key endogenous regulators of plant development. Although cytokinin-mediated modulation of auxin distribution is a developmentally crucial hormonal interaction, its molecular basis is largely unknown. Here we show a direct regulatory link between cytokinin signalling and the auxin transport machinery uncovering a mechanistic framework for cytokinin-auxin cross-talk. We show that the CYTOKININ RESPONSE FACTORS (CRFs), transcription factors downstream of cytokinin perception, transcriptionally control genes encoding PIN-FORMED (PIN) auxin transporters at a specific PIN CYTOKININ RESPONSE ELEMENT (PCRE) domain. Removal of this cis-regulatory element effectively uncouples PIN transcription from the CRF-mediated cytokinin regulation and attenuates plant cytokinin sensitivity. We propose that CRFs represent a missing cross-talk component that fine-tunes auxin transport capacity downstream of cytokinin signalling to control plant development

    Caracterización nanotecnológica de madera de café

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    El objetivo general del proyecto es aprovechar la madera de café para el desarrollo de un envase inocuo para fermentar bebidas alcohólicas. Los antecedentes consultados, sugieren que los análisis realizados a escala nanotecnológica para este tipo de material, no se han efectuado anteriormente. Por medio de la técnica SEM para las muestras orgánicas no conductoras, se deben limpiar cuidadosamente, para que haya desprendimiento de electrones y sean captados por los sensores específicos del microscopio. Esta técnica es capaz de generar imágenes de alta resolución, lo que permite examinar características espacialmente cercanas en la muestra, con una gran magnificación y grado de detalle, debido a que la superficie del material es barrida con electrones, que son acelerados a través de un cañón. El microscopio, dispone de diversos sistemas de detección, con los que es posible diferenciar la señal producida por los electrones primarios (PE) y secundarios (SE). Los electrones secundarios son aquellos que se emplean generalmente para obtener una imagen realista de la superficie que estamos analizando y determinar su morfología. Con este tipo de análisis en la madera de café, se espera obtener características específicas de la composición elemental, así como las físico-morfológicas, que le aportarían propiedades diferenciales a los productos derivados. La importancia de este estudio, radica en aprovechar más de 1300 toneladas de residuos orgánicos, para los que alternativas convencionales como compostaje y venta para cocinar con leña, son insuficientes para el manejo efectivo de los volúmenes de desechos de los procesos productivos. En algunos casos, no se encuentran opciones viables para el manejo de la madera de café, además de alejar a la empresa de su actividad económica principal, no generar productos con valor agregado y utilidades significativas, desconociendo el valor industrial y comercial que aún poseen, una vez se les ha dado una disposición final en grandes cantidades de basura orgánica
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