705 research outputs found

    Recovery trends of commercial fish: the case of an underperforming Mediterranean marine protected area

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    Temporal trends in the recovery of exploited species in marine protected areas (MPAs) are useful for a proper assessment of the efficacy of protection measures. The effects of protection on the fish assemblages of the sublittoral rocky reefs in the \u201cPenisola del Sinis-Isola di Mal di Ventre\u201d MPA (W. Sardinia, Italy) were evaluated using a multi-year series of data. Four surveys, conducted 7, 10, 13 and 15 years after the area was designated as an MPA and carried out in the period spanning June and July, were used to estimate the abundance and biomass of commercial species. The surveys were carried out in zones with decreasing levels of fishing restrictions within the MPA (zones A, B, C) and in unprotected zones (OUT1 and OUT2), and underwater video visual census techniques were used. Protected zones only occasionally showed higher levels of abundance or biomass, and the trajectories of those metrics were not consistent across the years. In addition, the zone with the highest level of protection (zone A) never presented levels of abundance and biomass higher than those in zones B and C. This study shows that even 15 years after designation, protection has had no appreciable effect in the MPA studied. It is argued that this is emblematic of several shortcomings in the planning, regulation and enforcement frameworks of the MPA

    Maternal mortality in 19th- and early 20th-century Italy

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    Although dramatically reduced in Western and developed countries, maternal mortality is still today one of the most relevant social and health scourges in developing countries. This is the reason why high levels of maternal mortality are always interpreted as a sign of low living standards, ignorance, poverty and woman discrimination. Maternal mortality represents, therefore, a very peculiar characteristic of demographic systems of ancien regime. Despite this important role in demographic systems, no systematic study has been addressed to investigate the impact of maternal mortality in historical Italy. The aim of this article is to shed some light on such a phenomenon by investigating its trend over time and the determinants in some Italian populations between the 18th and the early 20th centuries. The analysis will make use of civil and parish registers linked together by means of nominative techniques, and it will be, therefore, carried out at the micro level

    SHELF-LIFE OF HALAL FRESH SLICED BEEF AND MINCED MEAT

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    Microbiological and chemical-physical characterization of Halal beef fresh and minced meat, vacuum-packaged and stored at +2°C and +8°C, were examined, at 0, 7, 14 and 21 days, to evaluate the shelf-life. Lactic Acid Bacteria and Coliforms were higher in samples stored at +8 °C, particularly in minced meat. Pseudomonas were the most prevalent flora in all the products, and the contamination level, above 4 log10 cfu/g, were reached at 7 days in all the samples and was maintained during the study. The shelf-life can be extended reducing the storage temperature (< +2°C), and improving the packaging conditions

    Experimental Investigation on Thermal Diffusivity of PM Steels

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    The scanty literature data on thermal diffusivity of P/M steels seems contradictory, if the cooling speed on quenching is the evaluation parameter. Due to the basic importance of diffusivity on the response of P/M steels to heat-treating, an experimental survey has been carried out, to collect data on various P/M steels, based on prealloyed, or diffusion-bonded, or admixed powders. The study has also covered the influence of processing parameters, such as compaction pressure and sintering temperature. The flash method has been used to measure the thermal diffusivity of P/M steels. This method directly measures the thermal diffusivity of a sample in slab shape. A plane-parallel sample is inserted in the test apparatus and then a short light pulse, produced by a laser or a flash lamp, heats the front surface of the sample. The heat diffuses through the sample, leading to a temperature rise on the sample rear surface. An infrared detector measures this temperature rise, versus time, and thermal diffusivity is derived from the least square regression on the whole temperature trend, using the analytical solution of heat conduction. The results show that thermal diffusivity increases as density increases. This achievement can be justified by a simple theoretical analysis of the thermal conductivity on thermal diffusivity. The collected data also enable us to ascertain the influence of sintered material composition and carbon content on thermal diffusivity. The results should contribute to clarify some uncertainties and perplexities on the behavior of properly elaborated P/M steels, to be hardened by heat treatment, conventional – such as oil quenching – or innovative, such as sinter -hardening

    Experimental Tests of Conduction/Convection Heat Transfer in Very High Porosity Foams with Lattice Structures, Immersed in Different Fluids

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    This experimental work presents the results of measurements of thermal conductivity lambda and convection heat transfer coefficient h on regular structure PLA and aluminium foams with low density ratio (similar to 0.15), carried out with a TCP (thermal conductivity probe), built by the authors' laboratory. Measurements were performed with two fluids, water and air: pure fluids, and samples with the PLA and aluminium foams immersed in both fluids have been tested. Four temperatures (10, 20, 30, 40 degrees C) and various temperature differences during the tests Delta T (between 0.35 and 9 degrees C) were applied. Also, tests in water mixed with 0.5% of a gel (agar agar) have been run in order to increase the water viscosity and to avoid convection starting. For these tests, at the end of the heating, the temperature of the probe reaches steady-state values, when all the thermal power supplied by the probe is transferred to the cooled cell wall; thermal conductivity was also evaluated through the guarded hot ring (GHR) method. A difference was found between the results of lambda in steady-state and transient regimes, likely due to the difference of the sample volume interested by heating during the tests. Also, the effect of the temperature difference Delta T on the behaviour of the pure fluid and foams was outlined. The mutual effect of thermal conductivity and free convection heat transfer results in being extremely important to describe the behaviour of such kinds of composites when they are used to increase or to reduce the heat transfer, as heat conductors or insulators. Very few works are present in the literature about this subject, above all, ones regarding low-density regular structures

    Modeling and Measuring Thermodynamic and Transport Thermophysical Properties: A Review

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    The present review describes the up-to-date state of the evaluation of thermophysical prop erties (TP) of materials with three different procedures: modeling (also including inverse problems), measurements and analytical methods (e.g., through computing from other properties). Methods to measure specific heat and thermal conductivity are described in detail. Thermal diffusivity and thermal effusivity are a combination of the previously cited properties, but also for these proper ties, specific measurement and calculation methods are reported. Experiments can be carried out in steady-state, transient, and pulse regimes. For modeling, special focus is given to the inverse methods and parameter estimation procedures, because through them it is possible to evaluate the thermophysical property, assuring the best practices and supplying the measurement uncertainty. It is also cited when the most common data processing algorithms are used, e.g., the Gauss–Newton and Levenberg–Marquardt least squares minimization algorithms, and how it is possible to retrieve values of TP from other data. Optimization criteria for designing the experiments are also mentione

    Determination of automatic weather station self‐heating originating from accompanying electronics

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    open7openPavlasek, P.; Merlone, A.; Sanna, F.; Coppa, G.; Izquierdo, C. G.; Palencar, J.; Duris, S.Pavlasek, P.; Merlone, A.; Sanna, F.; Coppa, G.; Izquierdo, C. G.; Palencar, J.; Duris, S
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