4,479 research outputs found

    Experimental validation of a SAR-Based RFID localization technique exploiting an automated handling system

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    The synthetic aperture radar (SAR) approach has attracted a considerable interest in the context of phase-based techniques for the localization of UHF-RFID passive tags. In this letter, the results of an extensive experimental activity are presented, when the reader antenna is moved in front of a set of static passive UHF-RFID tags by means of a planar handling system. Measured performance is evaluated with respect to several system parameters: tag number and typology, tag reciprocal distance and orientation, trajectory and speed of the moving reader antenna. It is shown that the SAR processing can guarantee an accurate two-dimensional localization of multiple tags, with a localization error comparable to the size of typical commercial tags, by using a single reader antenna and without the need for any reference tag

    Back to the edge: relative coordinate system for use-wear analysis

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    Use-wear studies rely heavily on experiments and reference collections to infer the function of archeological artifacts. Sequential experiments, in particular, are necessary to understand how use-wear develops. Consequently, it is crucial to analyze the same location on the tool's surface during the course of an experiment. Being able to relocate the area of interest on a sample is also essential for reproducibility in use-wear studies. However, visual relocation has limited applicability and there is currently no easy and efficient alternative. Here we propose a simple protocol to create a coordinate system directly on the sample. Three ceramic beads that serve as reference markers are adhered onto the sample, either with epoxy resin or acrylic polymer. The former is easier to work with but the latter is reversible so it can be applied to archeological samples too. The microscope's software then relocates the position(s) of interest. We demonstrate the feasibility of this approach and measure its repeatability by imaging the same position on an experimental flint blade 10 times with two confocal microscopes. Our results show that the position can be relocated automatically with a horizontal positional repeatability of approximately 14% of the field of view. Quantitative surface texture measurements according to ISO 25178 vary due to this positional inaccuracy, but it is still unknown whether this variation would mask functional differences. Although still perfectible, we argue that this protocol represents an important step toward repeatability and reproducibility in experimental archeology, especially in use-wear studies.Funding Agency Romisch-Germanisches Zentralmuseum - Leibniz Research Institute for Archeology by German Federal and Rhineland Palatinate funding (Sondertatbestand "Spurenlabor")info:eu-repo/semantics/publishedVersio

    A large set of microsatellites for the highly invasive earthworm Amynthas corticis predicted from low coverage genomes

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    Invasive species can significantly affect local biodiversity and create important challenges for conservation. They usually present an outstanding plasticity that permits the adaptation to the new environments. Understanding their genetic background is fundamental to better comprehend invasion dynamics and elaborate proper management plans as well to infer population and evolutionary patterns. Here, we present a reasonable set of tools for the study of a highly invasive earthworm, the megascolecid Amynthas corticis. We designed in silico a large set of primers targeting microsatellite regions (ca. 9400) from two low coverage genomes presented here. This study provides 154 high quality primer pairs targeting polymorphic repeats conserved in two Amynthas corticis mitochondrial lineages. From this dataset, a set of primer pairs (15) was validated by polymerase chain reaction with 86% consistent amplification, confirming the accuracy of the in silico prediction. Nine of the primer pairs tested were selected for population genetics and presented polymorphism in the studied populations, thus showing promising potential for future studies of this global invasive species. The nuclear markers used in this study appear to recapitulate and complement the mitochondrial relationships found in a previous study. Interestingly, all genotyped individuals showed at least one triploid locus profile among the tested loci, which may be evidence of polyploidy associated to their life history, in particular to asexual reproduction by parthenogenesis

    The ALMA Early Science View of FUor/EXor objects. IV. Misaligned Outflows in the Complex Star-forming Environment of V1647 Ori and McNeil's Nebula

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    We present Atacama Large Millimeter/sub-millimeter Array (ALMA) observations of the star-forming environment surrounding V1647 Ori, an outbursting FUor/EXor pre-MS star. Dust continuum and the (J = 2 - 1) 12^{12}CO, 13^{13}CO, C18^{18}O molecular emission lines were observed to characterize the V1647 Ori circumstellar disc and any large scale molecular features present. We detect continuum emission from the circumstellar disc and determine a radius r = 40 au, inclination i = 17^{\circ}9+6^{+6}_{-9} and total disc mass of Mdisk_{\mathrm{disk}} of ~0.1 M_{\odot}. We do not identify any disc structures associated with nearby companions, massive planets or fragmentation. The molecular cloud environment surrounding V1647 Ori is both structured and complex. We confirm the presence of an excavated cavity north of V1647 Ori and have identified dense material at the base of the optical reflection nebula (McNeil's Nebula) that is actively shaping its surrounding environment. Two distinct outflows have been detected with dynamical ages of ~11,700 and 17,200 years. These outflows are misaligned suggesting disc precession over ~5500 years as a result of anisotropic accretion events is responsible. The collimated outflows exhibit velocities of ~2 km s1^{-1}, similar in velocity to that of other FUor objects presented in this series but significantly slower than previous observations and model predictions. The V1647 Ori system is seemingly connected by an "arm" of material to a large unresolved structure located ~20"" to the west. The complex environment surrounding V1647 Ori suggests it is in the early stages of star formation which may relate to its classification as both an FUor and EXor type object.Comment: 18 pages, 14 figures, 4 tables; accepted for publication in MNRA

    The ALMA Early Science View of FUor/EXor Objects - V. Continuum Disc Masses and Sizes

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    Low-mass stars build a significant fraction of their total mass during short outbursts of enhanced accretion known as FUor and EXor outbursts. FUor objects are characterized by a sudden brightening of ∼5 mag at visible wavelengths within 1 yr and remain bright for decades. EXor objects have lower amplitude outbursts on shorter time-scales. Here we discuss a 1.3 mm Atacama Large Millimeter/submillimeter Array (ALMA) mini-survey of eight outbursting sources (three FUors, four EXors, and the borderline object V1647 Ori) in the Orion Molecular Cloud. While previous papers in this series discuss the remarkable molecular outflows observed in the three FUor objects and V1647 Ori, here we focus on the continuum data and the differences and similarities between the FUor and EXor populations. We find that FUor discs are significantly more massive (∼80–600 MJup) than the EXor objects (∼0.5–40 MJup). We also report that the EXor sources lack the prominent outflows seen in the FUor population. Even though our sample is small, the large differences in disc masses and outflow activity suggest that the two types of objects represent different evolutionary stages. The FUor sources seem to be rather compact (Rc \u3c 20–40 au) and to have a smaller characteristic radius for a given disc mass when compared to T Tauri stars. V1118 Ori, the only known close binary system in our sample, is shown to host a disc around each one of the stellar components. The disc around HBC 494 is asymmetric, hinting at a structure in the outer disc or the presence of a second disc

    Núcleo Psicótico numa Psicose em Potencial Complexo de Mãe Morta e Psicose Branca: um estudo de caso

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    Este estudo teve como objetivo principal explorar dois conceitos importantes na teoria do psicanalista francês André Green: complexo de mãe morta e psicose branca. A decatexia provocada pelo afastamento emocional materno (complexo de mãe morta), induz um vazio interior (angústia branca). Esta sensação de vazio, de paragem, uma depressão sem afetos e a alucinação negativa, são manifestações da psicose branca (estrutura matriz onde se observa o núcleo da psicose sem que esta necessariamente se manifeste). O método utilizado foi o estudo de caso, de um sujeito do sexo masculino em regime de internamento. Os instrumentos de avaliação incluem a técnica projetiva de Rorschach (aplicada no início e no final do internamento) e o Thematic Apperception Test (aplicado no início do internamento). Através do material colhido em contexto de acompanhamento individual e das técnicas projetivas observaram-se pontos de contacto entre o conceito de psicose branca de Green, falso self de Winnicott e as personalidades “as if” de Helene Deutsch. A morte metafórica da mãe, o seu afastamento emocional, poderá estar na origem destas perturbações, onde se observa o núcleo da psicose. Nestas situações clínicas, em que o vazio interno predomina, a prática psicoterapêutica requer um posicionamento particular do clínico, que não deve estar nem muito próximo (sentido como intrusivo) nem muito distante (sentido como abandónico) do seu paciente. / This work had the purpose of exploring two important concepts in the theory of the French psychoanalyst André Green: the dead mother complex and the blank psychosis. The decathexis caused by a maternal emotional withdrawal (dead mother complex) induces an internal void (blank anguish). This feeling of emptiness, stoppage, a depression without affects and the negative hallucination are manifestations of blank psychosis (a matrix structure where one can observe the psychotic kernel, even though without having a manifest psychosis). The applied method was the case study, with a young male institutionalized subject, and to support it we used the Thematic Apperception Test (applied in the early phases of treatment) and the Rorschach projective technique (applied at the beginning and ending of the treatment). Through the data collected in the therapeutic sessions and the projective techniques applied, we observed points of contact between blank psychosis, Winnicott`s False Self and Helene Deutsch “as if” personalities. The mother’s metaphorical death, her emotional withdrawal, could be in the genesis of these disturbances, where we can observe the psychotic kernel. When we are dealing with this kind of patient, where the internal void prevails, the psychotherapeutic technique requires a special positioning from the therapist in relation to the patient, that shouldn’t be too close (experienced as intrusive), nor too distant (experienced with feelings of abandonment)

    Variations in hypoxia impairs muscle oxygenation and performance during simulated team-sport running

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    Purpose: To quantify the effect of acute hypoxia on muscle oxygenation and power during simulated team-sport running. Methods: Seven individuals performed repeated and single sprint efforts, embedded in a simulated team-sport running protocol, on a non-motorized treadmill in normoxia (sea-level), and acute normobaric hypoxia (simulated altitudes of 2,000 and 3,000 m). Mean and peak power was quantified during all sprints and repeated sprints. Mean total work, heart rate, blood oxygen saturation, and quadriceps muscle deoxyhaemoglobin concentration (assessed via near-infrared spectroscopy) were measured over the entire protocol. A linear mixed model was used to estimate performance and physiological effects across each half of the protocol. Changes were expressed in standardized units for assessment of magnitude. Uncertainty in the changes was expressed as a 90% confidence interval and interpreted via non-clinical magnitude-based inference. Results: Mean total work was reduced at 2,000 m (−10%, 90% confidence limits ±6%) and 3,000 m (−15%, ±5%) compared with sea-level. Mean heart rate was reduced at 3,000 m compared with 2,000 m (−3, ±3 min(−1)) and sea-level (−3, ±3 min(−1)). Blood oxygen saturation was lower at 2,000 m (−8, ±3%) and 3,000 m (−15, ±2%) compared with sea-level. Sprint mean power across the entire protocol was reduced at 3,000 m compared with 2,000 m (−12%, ±3%) and sea-level (−14%, ±4%). In the second half of the protocol, sprint mean power was reduced at 3,000 m compared to 2,000 m (−6%, ±4%). Sprint mean peak power across the entire protocol was lowered at 2,000 m (−10%, ±6%) and 3,000 m (−16%, ±6%) compared with sea-level. During repeated sprints, mean peak power was lower at 2,000 m (−8%, ±7%) and 3,000 m (−8%, ±7%) compared with sea-level. In the second half of the protocol, repeated sprint mean power was reduced at 3,000 m compared to 2,000 m (−7%, ±5%) and sea-level (−9%, ±5%). Quadriceps muscle deoxyhaemoglobin concentration was lowered at 3,000 m compared to 2,000 m (−10, ±12%) and sea-level (−11, ±12%). Conclusions: Simulated team-sport running is impaired at 3,000 m compared to 2,000 m and sea-level, likely due to a higher muscle deoxygenation

    Resolved Debris Discs Around A Stars in the Herschel DEBRIS Survey

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    The majority of debris discs discovered so far have only been detected through infrared excess emission above stellar photospheres. While disc properties can be inferred from unresolved photometry alone under various assumptions for the physical properties of dust grains, there is a degeneracy between disc radius and dust temperature that depends on the grain size distribution and optical properties. By resolving the disc we can measure the actual location of the dust. The launch of Herschel, with an angular resolution superior to previous far-infrared telescopes, allows us to spatially resolve more discs and locate the dust directly. Here we present the nine resolved discs around A stars between 20 and 40 pc observed by the DEBRIS survey. We use these data to investigate the disc radii by fitting narrow ring models to images at 70, 100 and 160 {\mu}m and by fitting blackbodies to full spectral energy distributions. We do this with the aim of finding an improved way of estimating disc radii for unresolved systems. The ratio between the resolved and blackbody radii varies between 1 and 2.5. This ratio is inversely correlated with luminosity and any remaining discrepancies are most likely explained by differences to the minimum size of grain in the size distribution or differences in composition. We find that three of the systems are well fit by a narrow ring, two systems are borderline cases and the other four likely require wider or multiple rings to fully explain the observations, reflecting the diversity of planetary systems.Comment: 19 pages, 13 figures, 6 tables. Accepted for publication in MNRA
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