25 research outputs found

    Pulsating Heat pipe only for Space (PHOS): Results of the REXUS 18 sounding rocket campaign

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    Two Closed Loop Pulsating Heat Pipes (CLPHPs) are tested on board REXUS 18 sounding rocket in order to obtain data over a relatively long microgravity period (approximately 90 s). The CLPHPs are partially filled with FC-72 and have, respectively, an inner tube diameter larger (3 mm) and slightly smaller (1.6 mm) than the critical diameter evaluated in static Earth gravity conditions. On ground, the small diameter CLPHP effectively works as a Pulsating Heat Pipe (PHP): the characteristic slug and plug flow pattern forms inside the tube and the heat exchange is triggered by thermally driven self-sustained oscillations of the working fluid. On the other hand, the large diameter CLPHP works as a two- phase thermosyphon in vertical position and doesn't work in horizontal position: in this particular condition, the working fluid stratifies within the device as the surface tension force is no longer able to balance buoyancy. Then, the idea to test the CLPHPs in reduced gravity conditions: as the gravity reduces the buoyancy forces becomes less intense and it is possible to recreate the typical PHP flow pattern also for larger inner tube diameters. This allows to increase the heat transfer rate and, consequently, to decrease the overall thermal resistance. Even though it was not possible to experience low gravity conditions due to a failure in the yoyo de-spin system, the thermal response to the peculiar acceleration field (hyper-gravity) experienced on board are thoroughly described

    Thermal inertia of Occator's faculae on Ceres

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    Thermal inertia is a key information to quantify the physical status of a planetary surface; it can be retrieved by comparison between theoretical and observed temperature diurnal profiles. We have calculated the surface temperature for a set of locations on Ceres' surface with a thermophysical model that provides temperature as a function of thermal conductivity and roughness, and we have determined the values of those parameters for which the best fit with the observed data is obtained. The observed temperatures have been retrieved form spatially-resolved data from the Dawn mission. In our previous work [Rognini et al., 2019], we have found that the average thermal inertia for the overall surface of Ceres is low (from 1 to 15 to 60 J m^-2 s^1⁄2 K^-1), as expected according to the general trend observed in the Solar System for atmosphere-less bodies, while the thermal inertia of the very bright faculae found in the floor of the Occator crater could not be well defined. Using more recently acquired VIR high resolution data we find that the central part of the Cerealia facula displays a thermal anomaly (~ 10 K above the average) compatible with a higher thermal inertia with respect to the surrounding regions, while the Vinalia facula does not display any consequently could have a grain size comparable with the Ceres’ surface average

    Giant neck neoplasm. Case report

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    Giant latero-cervical neoplasias usually originate in the parotid gland, as slow-growing adenomas, in subjects who take little care of their personal health. Giant adenomas of submandibular gland are very rare. These neoplasias involve prevalently male sex (male/female ratio: 2/1) and usually occur between 20 and 40 years of age. Signs of malignant transformation may be observed in the adenomatous epithelial component in a percentage ranging from 1% to 10% of cases. The case is reported of a giant malignant latero-cervical neoplasia originating from a pleomorph adenoma of the submandibular gland. The diagnostic work-up and treatment protocol are described

    Epstein-Barr virus-transformed human B lymphocytes produce natural antibodies to histones. Immunology Letters (Amsterdam, Olanda) 39, 277-282, 1994.

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    To study the mechanism(s) responsible for the appearance of Epstein-Barr virus (EBV)-induced anti-histone autoantibodies, peripheral blood B lymphocytes from healthy donors were infected with EBV and the resulting lymphoblastoid cell lines were tested for secretion of antibodies reacting with histones. It was found that EBV-transformed cells produce IgM antibody reactive with histones and that the frequency of EBV-inducible circulating B lymphocytes that produce antibodies to histones is at least 10(-5). Moreover, in cultures of tonsillar lymphoid cells, the enrichment in CD5+ B lymphocytes increases the percentage of EBV-transformed cultures making anti-histone IgM antibodies. EBV may therefore, also in vivo, induce natural anti-histone antibody by polyclonal B-cell activation without any requirement of antigen to trigger antibody response

    Towards multimodal Haptics for teleoperation: Design of a Tactile Thermal Display

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    Surgical robotics is among the most challenging applications of motion control. Present and future systems are essentially master-slave systems. Our work focuses on force-feedback and haptic interfaces. In this context, we study multimodal haptic interfaces, i.e. The fusion of force-feedback, with other tactile information such as temperature or pressure. First results support the proposition that such multimodal haptic devices can help improve surgeon's dexterity and motion control. In order to strengthen this point, we investigate the psychophysics of thermal perception. This paper presents a device for temperature feedback that can be integrated in a multimodal haptic console. A finger sized tactile temperature display able to generate temperature gradients under the fingertip is presented along with first measurement results. © 2012 IEEE

    Ceres observed at low phase angles by VIR-Dawn

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    Context. Particulate surfaces exhibit a surge of reflectance at low phase angles, a phenomenon referred to as the opposition effect (OE). Two mechanisms are recognized as responsible for the OE: shadow hiding (SH) and coherent backscattering. The latter is typically characterized by a small angular width of a few degrees at most and according to the theoretical prediction should exhibit wavelength and albedo dependence. Aims. We characterize the OE on the surface of Ceres using Dawn Visible InfraRed mapping spectrometer hyperspectral images at low phase angles. Furthermore, this dataset, coupled with previous observations, allows us to perform a complete spectrophotometric modeling at visual-to-infrared (VIS-IR) wavelengths (0.465-4.05 µm) in the broad phase angle range ≈ 0°-132°. Methods. We applied Hapke's theory to the average phase curve for Ceres. Disk-resolved properties of the OE were investigated through an empirical model. Results. Across the investigated phase angle interval, Ceres' average phase curve exhibits a smaller back-scattering contribution for increasing wavelengths. This determines a progressive spectral reddening at larger phase angles that we hypothesize as being related to the effect of submicron roughness on the grain surface. In the OE region, the shape of the phase curves is fairly constant across the VIS range and no sharp opposition surge at very small phase angles (α < 2°) can be recognized. This would suggest a major contribution from SH to Ceres' OE. Assuming SH as the dominant mechanism, from the OE angular width we infer a high surface porosity (≈0.9), which appears in good qualitative agreement with Ceres' low thermal inertia. Thanks to the OE observations we derive Ceres’ VIS-IR geometric albedo with a reference value at 0.55 µm of 0.098±0.007. Mapping of the VIS normal albedo and OE angular width across a portion of the surface of Ceres does not reveal a spatial correlation between these quantities, consistent with SH dominating in the α = 0°-7° interval. The comparison of Ceres' V-band magnitude curve with that of other asteroids indicates that Ceres' OE is typical of a low-albedo object and compatible with the C-class type

    Thought consciousness and source monitoring depend on robotically controlled sensorimotor conflicts and illusory states.

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    Thought insertion (TI) is characterized by the experience that certain thoughts, occurring in one's mind, are not one's own, but the thoughts of somebody else and suggestive of a psychotic disorder. We report a robotics-based method able to investigate the behavioral and subjective mechanisms of TI in healthy participants. We used a robotic device to alter body perception by providing online sensorimotor stimulation, while participants performed cognitive tasks implying source monitoring of mental states attributed to either oneself or another person. Across several experiments, conflicting sensorimotor stimulation reduced the distinction between self- and other-generated thoughts and was, moreover, associated with the experimentally generated feeling of being in the presence of an alien agent and subjective aspects of TI. Introducing a new robotics-based approach that enables the experimental study of the brain mechanisms of TI, these results link TI to predictable self-other shifts in source monitoring and specific sensorimotor processes
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