X-ray study of bow shocks in runaway stars

Massive runaway stars produce bow shocks through the interaction of their winds with the interstellar medium, with the prospect for particle acceleration by the shocks. These objects are consequently candidates for non-thermal emission. Our aim is to investigate the X-ray emission from these sources. We observed with XMM-Newton a sample of five bow shock runaways, which constitutes a significant improvement of the sample of bow shock runaways studied in X-rays so far. A careful analysis of the data did not reveal any X-ray emission related to the bow shocks. However, X-ray emission from the stars is detected, in agreement with the expected thermal emission from stellar winds. On the basis of background measurements we derive conservative upper limits between 0.3 and 10 keV on the bow shocks emission. Using a simple radiation model, these limits together with radio upper limits allow us to constrain some of the main physical quantities involved in the non-thermal emission processes, such as the magnetic field strength and the amount of incident infrared photons. The reasons likely responsible for the non-detection of non-thermal radiation are discussed. Finally, using energy budget arguments, we investigate the detectability of inverse Compton X-rays in a more extended sample of catalogued runaway star bow shocks. From our analysis we conclude that a clear identification of non-thermal X-rays from massive runaway bow shocks requires one order of magnitude (or higher) sensitivity improvement with respect to present observatories.Fil: del Valle, Maria Victoria. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Instituto Argentino de Radioastronomía. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto Argentino de Radioastronomía; ArgentinaFil: Romero, Gustavo Esteban. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Instituto Argentino de Radioastronomía. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto Argentino de Radioastronomía; ArgentinaFil: Peri, Cintia Soledad. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Instituto Argentino de Radioastronomía. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto Argentino de Radioastronomía; ArgentinaFil: Benaglia, Paula. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Instituto Argentino de Radioastronomía. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto Argentino de Radioastronomía; ArgentinaFil: De Becker, M.. Université de Liège; Bélgic

G337.2+0.1: a new X-ray supernova remnant?

We present evidence supporting a SNR origin for the radio source G337.2+0.1, which was discovered along the line of sight to the Norma spiral arm in the MOST 843-MHz radio survey. The radio source is spatially superposed to the unidentified ASCA source AX J1635.9-4719. An analysis of this latter source reveals that its X-ray spectrum, extended nature, and non-variable flux are consistent with what is expected for a SNR. In addition, we have used HI-line observations of the region to look for any effect of the presumed remnant on the ISM. We have found a well-defined minimum centered at the position of the radio source in the velocity range of ~ -25 to -19 km s-1. This feature appears as a sharp absorption dip in the spectrum that might be produced when the continuum emission from the SNR candidate is absorbed by foreground gas. Hence we have used it to constrain the distance to the source, which seems to be a young (age ~ a few 103 yr) and distant (d ~ 14 kpc) SNR. G337.2+0.1 and AX J1635.9-4719 would be the radio/X-ray manifestations of this remnant.Facultad de Ciencias Astronómicas y GeofísicasInstituto Argentino de Radioastronomí

Deeper Chandra Follow-up of Cygnus TeV Source Perpetuates Mystery

A 50 ksec Chandra observation of the unidentified TeV source in Cygnus reported by the HEGRA collaboration reveals no obvious diffuse X-ray counterpart. However, 240 Pointlike X-ray sources are detected within or nearby the extended TeV J2032+4130 source region, of which at least 36 are massive stars and 2 may be radio emitters. That the HEGRA source is a composite, having as counterpart the multiple point-like X-ray sources we observe, cannot be ruled out. Indeed, the distribution of point-like X-ray sources appears non-uniform and concentrated broadly within the extent of the TeV source region. We offer a hypothesis for the origin of the very high energy gamma-ray emission in Cyg OB2 based on the local acceleration of TeV range cosmic rays and the differential distribution of OB vs. less massive stars in this association.Comment: Substantially revised version; incorporates referee suggestions & expanded discussio

An investigation into the fraction of particle accelerators among colliding-wind binaries : Towards an extension of the catalogue

Particle-accelerating colliding-wind binaries (PACWBs) are multiple systems made of early-type stars able to accelerate particles up to relativistic velocities. The relativistic particles can interact with different fields (magnetic or radiation) in the colliding-wind region and produce non-thermal emission. In many cases, non-thermal synchrotron radiation might be observable and thus constitute an indicator of the existence of a relativistic particle population in these multiple systems. To date, the catalogue of PACWBs includes about 40 objects spread over many stellar types and evolutionary stages, with no clear trend pointing to privileged subclasses of objects likely to accelerate particles. This paper aims at discussing critically some criteria for selecting new candidates among massive binaries. The subsequent search for non-thermal radiation in these objects is expected to lead to new detections of particle accelerators. On the basis of this discussion, some broad ideas for observation strategies are formulated. At this stage of the investigation of PACWBs, there is no clear reason to consider particle acceleration in massive binaries as an anomaly or even as a rare phenomenon. We therefore consider that several PACWBs will be detected in the forthcoming years, essentially using sensitive radio interferometers which are capable of measuring synchrotron emission from colliding-wind binaries. Prospects for high-energy detections are also briefly addressed.Facultad de Ciencias Astronómicas y GeofísicasInstituto Argentino de Radioastronomí

Experimental study of dielectric barrier discharge in mixtures of carbon dioxide and oxygen

Carbon dioxide decomposition in mixtures of CO2and O2has been experimentally investigatedusing dielectric barrier discharge, with special interest on O3and COproductions. Experiments have been conducted at different frequencies and operating voltages, and the concentration of O3and COhave been measured by means of absorption spectroscopy in the UV and in the IR regions. According to the observations, theproductionof both speciescan be substantially increased by adding molecular oxygento carbon dioxide, even in small proportion

Food web structure shaped by habitat size and climate across a latitudinal gradient

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Habitat size and climate are known to affect the trophic structure and dynamics of communities, but their interactive effects are poorly understood. Organisms from different trophic levels vary in terms of metabolic requirements and heat dissipation. Indeed, larger species such as keystone predators require more stable climatic conditions than their prey. Likewise, habitat size disproportionally affects large-sized predators, which require larger home ranges and are thus restricted to larger habitats. Therefore, food web structure in patchy ecosystems is expected to be shaped by habitat size and climate variations. Here we investigate this prediction using natural aquatic microcosm (bromeliad phytotelmata) food webs composed of litter resources (mainly detritus), detritivores, mesopredators, and top predators (damselflies). We surveyed 240 bromeliads of varying sizes (water retention capacity) across 12 open restingas in SE Brazil spread across a wide range of tropical latitudes (-12.6 degrees to -27.6 degrees, ca. 2,000km) and climates ( mean annual temperature=5.3 degrees C). We found a strong increase in predator-to-detritivore mass ratio with habitat size, which was representative of a typical inverted trophic pyramid in larger ecosystems. However, this relationship was contingent among the restingas; slopes of linear models were steeper in more stable and favorable climates, leading to inverted trophic pyramids (and top-down control) being more pronounced in environments with more favorable climatic conditions. By contrast, detritivore-resource and mesopredator-detritivore mass ratios were not affected by habitat size or climate variations across latitudes. Our results highlight that the combined effects of habitat size, climate and predator composition are pivotal to understanding the impacts of multiple environmental factors on food web structure and dynamics.Habitat size and climate are known to affect the trophic structure and dynamics of communities, but their interactive effects are poorly understood. Organisms from different trophic levels vary in terms of metabolic requirements and heat dissipation. Inde971027052715FAPESP - FUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULOCNPQ - CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICOFINANCIADORA DE ESTUDOS E PROJETOS - FINEPFundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)sem informação550022/2014- 701.13.0353.00The authors thank three anonymous reviewers for the valua-ble comments on the first edition of this report. A. L. Mendonça helped with invertebrate surveys, and identifications were con-ducted by L. C. de Pinho (Chironomidae), A. L. Mendonça (Culicidae), M

Ozone production by corona discharge using a hollow needle-plate electrode system

Ozone generation using a hollow needle-to-plate corona reactor has been investigated using both positive and negative polarities and various flow rates. Oxygen could be introduced in the reactor either through the needle electrode or through a port on the lateral wall. This configuration al-lowed studying the effect of the flow direction on ozone production

Desigualdades de género en la producción del cuidado

En este trabajo nos preguntamos por el reconocimiento de la desigualdad de género en  la producción del cuidado en salud desde la perspectiva de sus propias trabajadoras y  trabajadores. Su objetivo consiste en analizar las narrativas de trabajadores y trabajadoras  de salud pública acerca de las diferencias entre varones y mujeres en la producción  del cuidado en los espacios públicos de trabajo y en los ámbitos domésticos. Con una  aproximación cualitativa con enfoque etnográfico y perspectiva de género, realizamos  entrevistas en profundidad con trabajadoras y trabajadores de salud pública de diversas  profesiones y ocupaciones y observación participante en hospitales y centros de salud  de Mar del Plata y zonas rurales durante el año 2021. El análisis de las narrativas fue de  tipo hermenéutico. Encontramos que la desigualdad de género que existe en el sector  salud no es visibilizada en los ámbitos laborales, mientras que aquella es observada en  los ámbitos domésticos. Discutimos los resultados desde los aportes de los estudios de  género y el feminismo en el contexto histórico y político actual. In this paper we ask about the recognition of gender inequality in the production of  health care from the perspective of health workers. The purpose is to analyze the narratives  of public health workers about the differences between men and women in the  production of care in public work spaces and in domestic settings. From a qualitative  approach and an ethnographic and gender perspective, we conducted in-depth interviews  with public health workers from various professions and occupations and participant  observation in hospitals and health centers in Mar del Plata and rural areas  during the year 2021. The analysis of the narratives was hermeneutical. We found that  the gender inequality that exists in the health sector is not visible in the workplace, while  it is observed in the domestic spheres. We discuss the results from the contributions of  gender studies and feminism in the current historical and political context. En este trabajo nos preguntamos por el reconocimiento de la desigualdad de género en  la producción del cuidado en salud desde la perspectiva de sus propias trabajadoras y  trabajadores. Su objetivo consiste en analizar las narrativas de trabajadores y trabajadoras  de salud pública acerca de las diferencias entre varones y mujeres en la producción  del cuidado en los espacios públicos de trabajo y en los ámbitos domésticos. Con una  aproximación cualitativa con enfoque etnográfico y perspectiva de género, realizamos  entrevistas en profundidad con trabajadoras y trabajadores de salud pública de diversas  profesiones y ocupaciones y observación participante en hospitales y centros de salud  de Mar del Plata y zonas rurales durante el año 2021. El análisis de las narrativas fue de  tipo hermenéutico. Encontramos que la desigualdad de género que existe en el sector  salud no es visibilizada en los ámbitos laborales, mientras que aquella es observada en  los ámbitos domésticos. Discutimos los resultados desde los aportes de los estudios de  género y el feminismo en el contexto histórico y político actual.&nbsp

Nanopartículas metálicas funcionalizadas con el neuropéptido VIP y procedimiento de preparación

Nanopartículas metálicas funcionalizadas con el neuropéptido VIP y procedimiento de preparación. Constituye el objeto de la presente invención nanopartículas metálicas funcionalizadas con el neuropéptido VIP, así como el procedimiento de preparación de dichas nanopartículas. Las nanopartículas objeto de la presente invención presentan uniones selectivas de nanopartículas a péptidos en dos orientaciones posibles, grupo NH2 o grupo COOH. En esta última orientación, los péptidos si son reconocidos por los receptores de membranas celulares, lo que proporciona una herramienta que permite discernir efectos dependientes e independientes de receptor. El péptido empleado ha sido el VIP, mediante el cual se obtiene un amplio espectro de funciones biológicas, incluida inmunomodulación, actuando predominantemente como un potente anti-inflamatorio y un agente inhibidor de la respuesta del Th1 en el sistema inmunitario y emergiendo como un importante factor terapéutico para el tratamiento de enfermedades con componentes inflamatorias y autoinmunes.Universidad Pablo de Olavide, Universidad de Sevilla, Consejo Superior de Investigaciones Científicas (España), Fundación Reina Mercedes para la Investigación SanitariaA1 Solicitud de patentes con informe sobre el estado de la técnic