6,461 research outputs found

    Launching Systems for Unmanned Vehicles Onboard Naval Vessels

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    Unmanned vehicles can replace humans in humanitarian and military operations, requiring ships to have innovative capabilities for launching and recovering them. However, the variety of unmanned vehicles makes it difficult to create standardized interfaces, and their development often outpaces the lifespan of ships. Integrating unmanned vehicles on naval vessels is complex due to technical requirements and limited space. Engineers must consider cost efficiency, flexibility, and operational impact. This paper presents technologies and solutions for launching unmanned aerial vehicles (UAVs) from front-line ships, with their pros and cons. To this end, Fuzzy Analytic Hierarchy Process (F AHP) has been here employed to rank the main options. Among them, the electromagnetic catapult is the most promising option for launching UAVs from front-line naval ships and it is worthy of further development. Besides, despite having limited capacity, bungee cords can be used until the technology of the electromagnetic catapult is tested and ready to take the place of the former

    Next generation Amphibious Vessel: an innovative power and propulsion system

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    The main purpose of Navy amphibious ships is to transport Marines, their weapons, equipment, and supplies toward distant operating areas to enable the conduction of expeditionary operations ashore. Although amphibious ships can be used to support Marines' landings against opposing military forces, they are also employed for operations in peace. This kind of vessel has large storage capability, which enables them to operate helicopters and landing crafts for the transfer of personnel and supplies from ship to shore without the need for port facilities. Thanks to their versatility, amphibious ships are in force in all major Navies. The main purpose of this paper is to carry out a study about the power and propulsion system of the next-generation Landing Platform Dock. This study proposes an innovative Integrated Electrical and Electronic Power System with a DC zonal power distribution system and full electric pod propulsion. The DC zonal power distribution will allow the installation onboard of innovative components and weapons (e.g., Laser Gun and modular fixed-face radar), while pod propulsion will improve the dynamic positioning capability, a key feature for this type of ship

    A polyphenol-rich extract from an oenological oak-derived tannin influences in vitro maturation of porcine oocytes

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    Tannins have been demonstrated to have antioxidant and various health benefit properties. The aim of this study was to determine the effect of an ethanol extract (TRE) of a commercial oenological tannin (Quercus robur toasted oak wood, Tan'Activ R \uae ) on female gamete using an in vitro model of pig oocyte maturation (IVM) and examining nuclear maturation, cytoplasmic maturation, intracellular GSH and ROS levels and cumulus cell steroidogenesis. To this aim, during IVM performed in medium either supplemented (IVM A) or not supplemented (IVM B) with cysteine and \u3b2-mercaptoethanol, TRE was added at different concentrations (0, 1, 5, 10, 20 \u3bcg/ml). The addition of TRE at all the concentration tested to either IVM A or IVM B, did not influence oocyte nuclear maturation. When IVM was performed in IVM A, no effect was induced on cytoplasmic maturation by TRE at the concentration of 1, 5 and 10 \u3bcg/ml, while TRE 20 \u3bcg/ml significantly reduced the penetration rate after IVF (p < 0.05) and the blastocyst rate after parthenogenetic activation (p < 0.01). Oocyte maturation in IVM B, compared to IVM A group, decreased GSH (p < 0.001) and increased ROS (p < 0.01) intracellular levels and in turn impaired oocyte cytoplasmic maturation reducing the ability to sustain male pronuclear formation after IVM (p < 0.001) and the developmental competence after parthenogenetic activation (p < 0.001). TRE supplementation to IVM B significantly reduced ROS production (5, 10, 20 \u3bcg/ml TRE) to levels similar to IVM A group, and increased GSH levels (10, 20 \u3bcg/ml TRE) compared to IVM B (p < 0.05) without reaching those of IVM A group. TRE supplementation to IVM B at the concentrations of 1, 5 and 10 \u3bcg/ml significantly improved (p < 0.001) oocyte cytoplasmic maturation enhancing the ability to sustain male pronuclear formation without reaching, however, IVM A group levels. TRE addition at all the concentration tested to both IVM A and IVM B, did not induce any effect on E2 and P4 secretion by cumulus cells suggesting that the biological effect of the ethanol extract is not exerted thought a modulation of cumulus cell steroidogenesis. In conclusion, TRE, thanks to its antioxidant activity, was partially able to reduce the negative effect of the absence of cysteine and \u3b2-mercaptoethanol in IVM B, while TRE at high concentration in IVM A was detrimental for oocyte cytoplasmic maturation underlying the importance of maintaining a balanced redox environment during oocyte maturation

    Acquired heart block: A possible complication of patent ductus arteriosus in a preterm infant

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    A large patent ductus arteriosus (PDA) is a frequently encountered clinical problem in extremely low birth weight (ELBW) infants. It leads to an increased pulmonary blood flow and in a decreased or reversed diastolic flow in the systemic circulation, resulting in complications. Here we report a possible complication of PDA not previously published. On day 8 of life, a male ELBW infant (birth weight 650 g) born at a gestational age of 23 weeks and 3 days developed an atrioventricular block (AV block). The heart rate dropped from 168/min to 90/min, and the ECG showed a Wenckebach second-degree AV block and intraventricular conduction disturbances. Echocardiography demonstrated a PDA with a large left-to-right shunt and large left atrium and left ventricle with high contractility. Within several minutes after surgical closure of the PDA, the heart rate increased, and after 30 min the AV block had improved to a 1: 1 conduction ratio. Echocardiography after 2 h revealed a significant decrease of the left ventricular and atrial dimensions. Within 12 h, the AV block completely reversed together with the intraventricular conduction disturbances. We suggest that PDA with a large left-to-right shunt and left ventricular volume overload may lead to an AV block in an ELBW infant. Surgical closure of the PDA may be indicated. Copyright (C) 2007 S. Karger AG, Basel

    Boltzmann Suppression of Interacting Heavy Particles

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    Matsumoto and Yoshimura have recently argued that the number density of heavy particles in a thermal bath is not necessarily Boltzmann-suppressed for T << M, as power law corrections may emerge at higher orders in perturbation theory. This fact might have important implications on the determination of WIMP relic densities. On the other hand, the definition of number densities in a interacting theory is not a straightforward procedure. It usually requires renormalization of composite operators and operator mixing, which obscure the physical interpretation of the computed thermal average. We propose a new definition for the thermal average of a composite operator, which does not require any new renormalization counterterm and is thus free from such ambiguities. Applying this definition to the model of Matsumoto and Yoshimura we find that it gives number densities which are Boltzmann-suppressed at any order in perturbation theory. We discuss also heavy particles which are unstable already at T=0, showing that power law corrections do in general emerge in this case.Comment: 7 pages, 5 figures. New section added, with the discussion of the case of an unstable heavy particle. Version to appear on Phys. Rev.

    CALDER - Neutrinoless double-beta decay identification in TeO2_2 bolometers with kinetic inductance detectors

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    Next-generation experiments searching for neutrinoless double-beta decay must be sensitive to a Majorana neutrino mass as low as 10 meV. CUORE, an array of 988 TeO2_2 bolometers being commissioned at Laboratori Nazionali del Gran Sasso in Italy, features an expected sensitivity of 50-130 meV at 90% C.L, that can be improved by removing the background from α\alpha radioactivity. This is possible if, in coincidence with the heat release in a bolometer, the Cherenkov light emitted by the β\beta signal is detected. The amount of light detected is so far limited to only 100 eV, requiring low-noise cryogenic light detectors. The CALDER project (Cryogenic wide-Area Light Detectors with Excellent Resolution) aims at developing a small prototype experiment consisting of TeO2_2 bolometers coupled to new light detectors based on kinetic inductance detectors. The R&D is focused on the light detectors that could be implemented in a next-generation neutrinoless double-beta decay experiment.Comment: 8 pages, 3 figures, added reference to first result

    Pulse Shape Analysis with scintillating bolometers

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    Among the detectors used for rare event searches, such as neutrinoless Double Beta Decay (0ν\nuDBD) and Dark Matter experiments, bolometers are very promising because of their favorable properties (excellent energy resolution, high detector efficiency, a wide choice of different materials used as absorber, ...). However, up to now, the actual interesting possibility to identify the interacting particle, and thus to greatly reduce the background, can be fulfilled only with a double read-out (i.e. the simultaneous and independent read out of heat and scintillation light or heat and ionization). This double read-out could greatly complicate the assembly of a huge, multi-detector array, such as CUORE and EURECA. The possibility to recognize the interacting particle through the shape of the thermal pulse is then clearly a very interesting opportunity. While detailed analyses of the signal time development in purely thermal detectors have not produced so far interesting results, similar analyses on macro-bolometers (\sim10-500 g) built with scintillating crystals showed that it is possible to distinguish between an electron or γ\gamma-ray and an α\alpha particle interaction (i.e. the main source of background for 0ν\nuDBD experiments based on the bolometric technique). Results on pulse shape analysis of a CaMoO4_4 crystal operated as bolometer is reported as an example. An explanation of this behavior, based on the energy partition in the heat and scintillation channels, is also presented.Comment: Presented at the 14th International Workshop on Low Temperature Detectors, proceedings to be published in the Journal of Low Temperature Physic

    Iodine uptake and distribution in horticultural and fruit tree species.

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    Iodine is an essential microelement for humans and iodine deficiency disorder (IDD) is one of the most widespread nutrient-deficiency diseases in the world. Iodine biofortification of plants provides an attractive opportunity to increase iodine intake in humans and to prevent and control IDD. This study was conducted to investigate the iodine uptake and accumulation in edible portion of two fruit trees: plum and nectarine, and two horticultural crops: tomato and potato. Two type of iodine treatments (soil and foliar spray application), and, for fresh market tomato, two production systems (open field and greenhouse hydroponic culture) were tested. The distribution of iodine in potato stem and leaves, and in plum tree fruits, leaves, and branches was investigated. Iodine content of potato tubers after postharvest storage and processing (cooking), and iodine content of nectarine fruits after postharvest storage and processing (peeling) were also determined. Differences in iodine accumulation were observed among the four crops, between applications, and between production systems. In open field, the maximum iodine content ranged from 9.5 and 14.3 \u3bcg 100 g 121 for plum and nectarine fruit, to 89.4 and 144.0 \u3bcg 100 g 121 for potato tuber and tomato fruit, respectively. These results showed that nectarine and plum tree accumulated significantly lower amounts of iodine in their edible tissues, in comparison with potato and tomato. The experiments also indicated hydroponic culture as the most efficient system for iodine uptake in tomato, since its fresh fruits accumulated up to 2423 \u3bcg 100 g 121 of iodine. Iodine was stored mainly in the leaves, in all species investigated. Only a small portion of iodine was moved to plum tree branches and fruits, and to potato stems and tubers. No differences in iodine content after fruit peeling was observed. A significant increase in iodine content of potato was observed after baking, whereas a significant decrease was observed after boiling. We concluded that iodine biofortified fresh market tomato salad, both from field and hydroponics cultivation, and baked potatoes can be considered as potential functional foods for IDD prevention

    Size-resolved aerosol composition at an urban and a rural site in the Po Valley in summertime: implications for secondary aerosol formation

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    The aerosol size-segregated chemical composition was analyzed at an urban (Bologna) and a rural (San Pietro Capofiume) site in the Po Valley, Italy, during June and July 2012, by ion-chromatography (major water-soluble ions and organic acids) and evolved gas analysis (total and water-soluble carbon), to investigate sources and mechanisms of secondary aerosol formation during the summer. A significant enhancement of secondary organic and inorganic aerosol mass was observed under anticyclonic conditions with recirculation of planetary boundary layer air but with substantial differences between the urban and the rural site. The data analysis, including a principal component analysis (PCA) on the size-resolved dataset of chemical concentrations, indicated that the photochemical oxidation of inorganic and organic gaseous precursors was an important mechanism of secondary aerosol formation at both sites. In addition, at the rural site a second formation process, explaining the largest fraction (22 %) of the total variance, was active at nighttime, especially under stagnant conditions. Nocturnal chemistry in the rural Po Valley was associated with the formation of ammonium nitrate in large accumulation-mode (0.42–1.2 µm) aerosols favored by local thermodynamic conditions (higher relative humidity and lower temperature compared to the urban site). Nocturnal concentrations of fine nitrate were, in fact, on average 5 times higher at the rural site than in Bologna. The water uptake by this highly hygroscopic compound under high RH conditions provided the medium for increased nocturnal aerosol uptake of water-soluble organic gases and possibly also for aqueous chemistry, as revealed by the shifting of peak concentrations of secondary compounds (water-soluble organic carbon (WSOC) and sulfate) toward the large accumulation mode (0.42–1.2 µm). Contrarily, the diurnal production of WSOC (proxy for secondary organic aerosol) by photochemistry was similar at the two sites but mostly affected the small accumulation mode of particles (0.14–0.42 µm) in Bologna, while a shift to larger accumulation mode was observed at the rural site. A significant increment in carbonaceous aerosol concentration (for both WSOC and water-insoluble carbon) at the urban site was recorded mainly in the quasi-ultrafine fraction (size range 0.05–0.14 µm), indicating a direct influence of traffic emissions on the mass concentrations of this range of particles
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