Orbital characterization of superbolides observed from space: dynamical association with near-Earth objects, meteoroid streams and identification of hyperbolic meteoroids

There is an unceasing incoming flux of extraterrestrial materials reaching the Earth's atmosphere. Some of these objects produce luminous columns when they ablate during the hypersonic encounter with air molecules. A few fireballs occur each year bright enough to be detected from space. The source of these events is still a matter of debate, but it is generally accepted that they are of sporadic origin. We studied the NASA-JPL Center for NEOs Studies (CNEOS) fireball database to infer the dynamic origin of large bolides produced by meter-sized projectiles that impacted our planet. These likely meteorite-dropping events were recorded by the US Government satellite sensors. We estimated the false-positive rate and analyzed the time evolution of multiple orbit dissimilarity criteria concerning potential associations with near-Earth objects and meteoroid streams. We found that at least 16% of the large bolides could be associated with meteoroid streams, about 4% are likely associated with near-Earth asteroids, and 4% may be linked to near-Earth comets. This implies that a significant fraction of meter-sized impactors producing large bolides may have an asteroidal or cometary origin. In addition, we found at least three bolides having hyperbolic orbits with high tensile strength values. Meter-sized meteoroids of interstellar origin could be more common than previously thought, representing about 1% of the flux of large bolides. The inferred bulk physical properties suggest that the interstellar medium could bias these projectiles towards high strength rocks with the ability to survive prolonged exposure to the harsh interstellar space conditions.Comment: Accepted for publication in The Astronomical Journal (AAS38905R1

Modelo dinámico de un sistema de control de par por cuatro giróscopos

The dynamic model of a Four Control Moment Gyroscope (4-CMG) is traditionally obtained after computing the derivative of the angular momentum equation. Although this approach leads to a simple dynamic model, new models have been introduced due to terms not taken into account during the computation of the angular momentum equation. In this paper, a new dynamic model for a 4-CMG based on the Newton-Euler algorithm, which is well accepted in Robotics, was developed. This new approach produces a complete dynamic model. © The authors; licensee Universidad Nacional de Colombia

A photometric monitoring of bright high-amplitude delta Scuti stars. II. Period updates for seven stars

We present new photometric data for seven high-amplitude delta Scuti stars. The observations were acquired between 1996 and 2002, mostly in the Johnson photometric system. For one star (GW UMa), our observations are the first since the discovery of its pulsational nature from the Hipparcos data.The primary goal of this project was to update our knowledge on the period variations of the target stars. For this, we have collected all available photometric observations from the literature and constructed decades-long O-C diagrams of the stars. This traditional method is useful because of the single-periodic nature of the light variations. Text-book examples of slow period evolution (XX Cyg, DY Her, DY Peg) and cyclic period changes due to light-time effect (LITE) in a binary system (SZ Lyn) are updated with the new observations. For YZ Boo, we find a period decrease instead of increase. The previously suggested LITE-solution of BE Lyn (Kiss & Szatmary 1995) is not supported with the new O-C diagram. Instead of that, we suspect the presence of transient light curve shape variations mimicking small period changes.Comment: 11 pages, 15 figures, accepted for publication in A&

Pulsational frequencies of the eclipsing delta-Scuti star HD 172189

The eclipsing delta-Scuti star HD 172189 is a probable member of the open cluster IC 4756 and a promising candidate target for the CoRoT mission. The detection of pulsation modes is the first step in the asteroseismological study of the star. Further, the calculation of the orbital parameters of the binary system allows us to make a dynamical determination of the mass of the star, which works as an important constraint to test and calibrate the asteroseismological models. From a detailed frequency analysis of 210 hours of photometric data of HD 172189 obtained from the STEPHI XIII campaign we have identified six pulsation frequencies with a confidence level of 99% and a seventh with a 65% confidence level in the range between 100-300 uHz. In addiction, three eclipses were observed during the campaign, allowing us to improve the determination of the orbital period of the system.Comment: 6 pages, 7 figure

Producción enzimática de ésteres de citronelol

Los ésteres de citronelol son componentes de los aceites esenciales con diversos usos en la industria farmacéutica, cosmética y alimenticia. Estos compuestos pueden obtenerse por alcoholisis usando catalizadores químicos o biocatalizadores. En esta investigación se evalúa la síntesis enzimática de los mismos a partir de aceites vegetales y citronelol, realizándose un screening con cuatro lipasas comerciales en dos sistemas de reacción diferentes

Producción enzimática de ésteres de citronelol

Los ésteres de citronelol son componentes de los aceites esenciales con diversos usos en la industria farmacéutica, cosmética y alimenticia. Estos compuestos pueden obtenerse por alcoholisis usando catalizadores químicos o biocatalizadores. En esta investigación se evalúa la síntesis enzimática de los mismos a partir de aceites vegetales y citronelol, realizándose un screening con cuatro lipasas comerciales en dos sistemas de reacción diferentes

Ensayo clínico aleatorizado de una intervención intensiva sobre los estilos de vida de pacientes con hiperfibrinogenemia en prevención primaria de las enfermedades cardiovasculares en el ámbito de la atención primaria de salud

ObjetivosEstudiar el efecto de un programa intensivo de modificación del estilo de vida en los valores de fibrinógeno plasmático en pacientes sin enfermedad cardiovascular, con fibrinógeno elevado y valores normales de colesterol. Analizar si el efecto sobre el fibrinógeno es independiente del efecto sobre los lípidos.DiseñoEnsayo clínico controlado y aleatorizado.EmplazamientoOnce áreas básicas de L’Hospitalet de Llobregat y Barcelona.ParticipantesSe incluirá a 436 pacientes, 218 en cada grupo, de 35-75 años, sin enfermedad cardiovascular (cardiopatía isquémica, accidente cerebrovascular y arteriopatía periférica) con hiperfibrinogenemia (fibrinógeno > 300 mg/dl) y colesterol plasmático < 250 mg/dl.IntervencionesUn grupo de pacientes recibirá una intervención intensiva (en frecuencia e intensidad del consejo y tratamiento) sobre cambios de estilo de vida: dejar de fumar, dieta hipocalórica en caso de sobrepeso u obesidad y ejercicio físico. El seguimento del grupo intervención se realizará cada 2 meses. El grupo control seguirá los cuidados habituales.MedicionesSe determinarán los valores de fibrinógeno plasmático. Además, se registrarán otros acontecimientos de interés (modificación de los factores de riesgo, cambios en la calidad de vida, acontecimientos cardiovasculares y muerte) durante un seguimiento de 2 años.DiscusiónLa instauración de una intervención intensiva de prevención primaria (cambios de estilo de vida) en los pacientes que presentan hiperfibrinogenemia podría ser una medida más eficaz que la intervención habitual para reducir las cifras de fibrinógeno plasmático. Además, estas medidas podrían traducirse en una disminución del riesgo cardiovascular y en una mejora de la calidad de vida del paciente.ObjectivesTo study the effect of an intensive programme to modify life-style on levels of plasma fibrinogen in patients without cardiovascular pathology, with high fibrinogen and normal cholesterol levels. To analyse whether the effect on fibrinogen is independent, or otherwise, of the effect on lipids.DesignRandomised clinical trial with a control.Setting11 health districts in L’Hospitalet de Llobregat and Barcelona.Participants436 patients will be included, 218 individuals between 35 and 75 years old in each group, and without cardiovascular pathology (ischaemic cardiopathy, cerebral vascular accident or peripheral arteriopathy), with hyperfibrinogenaemia (fibrinogen ›300 mg/dL) and with plasma control ‹250 mg/dL.InterventionsOne group of patients will receive an intensive intervention (in frequency and intensity of counselling and treatment) for life-style changes, i.e. stopping smoking, low-calorie diet in case of overweight or obesity, and physical exercise. The follow-up of the intervention group will be every 2 months. The control group will follow customary treatments.MeasurementsLevels of plasma fibrinogen. In addition, other relevant events will be recorded over a 2-year monitoring period: modification of risk factors, changes in quality of life, cardiovascular events or death.DiscussionThe introduction of an intensive primary prevention intervention (life-style changes) in patients with hyperfibrinogenaemia could be a more effective measure than the habitual intervention for reducing plasma fibrinogen figures. In addition, these measures could be translated into a reduction of cardiovascular risk and an improvement in the patient́s quality of life

Factors affecting nectar sugar composition in chiropterophilic plants

AbstractMost pollinators prefer the sugars present in the nectar they consume, so it has been hypothesized that they have molded nectar trait evolution. However, nectar-feeding bats do not exhibit preferences for the sugars present in their diet. We analyzed the role that biochemical and ecological factors could play in shaping the nectar traits of chiropterophilic plants. We studied nectar traits and flower production in 49 plant species. We evaluated the relationship between nectar concentration and sugar composition using phylogenetically independent contrasts and if nectar traits were related to flower production using a Manova. We found that 42 species produced high hexoses nectars, and 7 species produced sucrose rich nectars. Phylogenetically independent contrasts showed that nectar concentration was negatively related to glucose content, positively related to fructose content, and was not related to sucrose content. A negative relationship was found from glucose and fructose contents to sucrose content, and glucose content was negatively related to fructose content. Finally, we did not found any relationship between nectar traits and the plants’ flowering strategies. We conclude that bat physiology and the relative low evolutionary time of the interaction between plants and bats may determine the lack of pattern in the nectar characteristics of chiropterophilic plants

Antiplatelet activity of isorhamnetin via mitochondrial regulation

Altres ajuts: Centro de Estudios en Alimentos Procesados-CEAP, ANID (National Doctorate Scholarship-Folio: 21191143, ANID R19A10001), Programa Regional R20F0001, Talca, Chile; CiberCV; Instituto Carlos III; Fundación de Investigación Cardiovascular-Fundación Jesús Serra, Spain.With the diet, we ingest nutrients capable of modulating platelet function, which plays a crucial role in developing cardiovascular events, one of the leading causes of mortality worldwide. Studies that demonstrate the antiplatelet and antithrombotic potential of bioactive compounds are vital to maintaining good cardiovascular health. In this work, we evaluate the flavonol isorhamnetin's antiplatelet effect on human platelets, using collagen, thrombin receptor activator peptide 6 (TRAP-6), and phorbol myristate acetate (PMA) as agonists. Isorhamnetin induced a significant inhibition on collagen-and TRAP-6-induced platelet aggregation, with half-maximum inhibitory concentration (IC) values of 8.1 ± 2.6 and 16.1 ± 11.1 µM, respectively; while it did not show cytotoxic effect. Isorhamnetin reduced adenosine triphosphate levels (ATP) in platelets stimulated by collagen and TRAP-6. We also evidenced that isorhamnetin's antiplatelet activity was related to the inhibition of mitochondrial function without effect on reactive oxygen species (ROS) levels. Additionally, we investigated isorhamnetin's effect on thrombus formation in vitro under flow conditions on the damaged vessel wall. In this context, we demonstrate that isorhamnetin at 20 µM induced a significant inhibition on platelet deposition, confirming its antithrombotic effect. Our findings corroborate the antiplatelet and antithrombotic potential of isorhamnetin present in many foods of daily consumption