3,549 research outputs found

    Effect of dietary administration of oil extract from rosemary on reproductive efficiency in boars

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    A decrease in reproductive performance in boars during and immediately after hot summer weather has been previously reported (Park and Yi, 2002). High temperature causes germ-cell destruction and results in a temporary decrease in sperm production and fertility. The increase of metabolic activity following thermic stress matches with a higher production of free radicals that impairs cells, such as spermatozoa, particularly rich in polyunsatured fatty acids and poor in antioxidants systems

    TrustShadow: Secure Execution of Unmodified Applications with ARM TrustZone

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    The rapid evolution of Internet-of-Things (IoT) technologies has led to an emerging need to make it smarter. A variety of applications now run simultaneously on an ARM-based processor. For example, devices on the edge of the Internet are provided with higher horsepower to be entrusted with storing, processing and analyzing data collected from IoT devices. This significantly improves efficiency and reduces the amount of data that needs to be transported to the cloud for data processing, analysis and storage. However, commodity OSes are prone to compromise. Once they are exploited, attackers can access the data on these devices. Since the data stored and processed on the devices can be sensitive, left untackled, this is particularly disconcerting. In this paper, we propose a new system, TrustShadow that shields legacy applications from untrusted OSes. TrustShadow takes advantage of ARM TrustZone technology and partitions resources into the secure and normal worlds. In the secure world, TrustShadow constructs a trusted execution environment for security-critical applications. This trusted environment is maintained by a lightweight runtime system that coordinates the communication between applications and the ordinary OS running in the normal world. The runtime system does not provide system services itself. Rather, it forwards requests for system services to the ordinary OS, and verifies the correctness of the responses. To demonstrate the efficiency of this design, we prototyped TrustShadow on a real chip board with ARM TrustZone support, and evaluated its performance using both microbenchmarks and real-world applications. We showed TrustShadow introduces only negligible overhead to real-world applications.Comment: MobiSys 201

    Efectos de la calidad de luz en la reproducción, crecimiento y contenido pigmentario de Gracilaria birdiae (Rhodophyta: Gracilariales)

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    Gracilaria species are the main source of agar worldwide. Since laboratory cultivation is an important means of sustaining such production, this study aimed to assess the influence of two fundamental strategies of physiological algae adjustment, photoacclimation and photomorphogenesis, on G. birdiae physiology. Specifically, the effects of different spectral light qualities on reproduction, growth, and pigment content in two distinct photoperiods (8 and 14 hours) were examined. Tetrasporophytes and gametophytes were submitted to different light qualities: white, green, red, and blue over the course of nine weeks. At the end of this period, chlorophyll a, allophycocyanin, phycocyanin, and phycoerythrin contents were analysed. Gametophytes showed reproductive structures only under monochromatic radiation. A stimulatory effect on tetrasporangium differentiation was mainly observed under red light, but this high fertility was negatively correlated with growth rate, i.e. algae cultivated under red light showed the lowest growth rate. However, while growth rates were higher in algae exposed to white light, they were similar to those observed in algae subjected to green light and 14 hours of daylight. PE was the predominant pigment, irrespective of light quality. Phycocyanin and phycoerythrin concentration increased when algae were cultivated under green and blue light. Therefore, considering future management prospects for G. birdiae mariculture, we suggest that red light could be utilized as a reproductive inductor to produce tetraspores. Furthermore, if the aim is to achieve high phycoerythrin content, continuous blue light could be applied during a short photoperiod. Indeed, the combination of different wavelengths could allow better economic resource exploitation.Las especies del género Gracilaria son la principal fuente de agar en el mundo. El desarrollo de técnicas de cultivo en laboratorio es importante para mejorar la producción, y por ello, este estudio tuvo como objetivo la evaluación de la influencia de dos estrategias de ajuste fisiológico de las algas, la fotoaclimatación y la fotomorfogénesis en G. birdiae. De modo más específico, se evaluaron los efectos de diferentes calidades espectrales de luz sobre la reproducción, crecimiento y contenido pigmentario bajo dos fotoperiodos (8 y 14 horas). Tetrasporofitos y gametofitos fueron sometidos a las siguientes calidades de luz: blanca (WH), verde (GR), rojo (RD) y azul (BL) a lo largo de nueve semanas. Al final del periodo, se analizaron los contenidos de clorofila a (Chl a), aloficocianina (APC), ficocianina (PC) y ficoeritrina (PE). Los gametofitos carecieron de estructuras reproductivas exclusivamente en radiación blanca. La diferenciación de tetrasporangios fue obtenida bajo estímulo de luz roja, pero fue negativamente correlacionado con las tasas de crecimiento (GRTs), presentando las tasas más bajas. Por otro lado, mientras las tasas de crecimiento fueron más altas en algas expuestas a luz WH, éstas fueron similares en algas mantenidas bajo luz GR y 14 horas de fotoperiodo. PE fue el pigmento predominante en G. birdiae, independientemente de la calidad de la luz aplicada. La concentración de PC y PE aumentaron cuando las algas recibieron luz GR y BL. De esa manera, considerando las perspectivas de manejo en la maricultura de G. birdiae, se sugiere que la luz roja puede ser utilizada como factor de inducción de la producción de tetrasporas. Por otro lado, las algas cultivadas en fotoperiodos cortos y luz BL alcanzaron altos contenidos de PE. La combinación de diferentes longitudes de onda puede permitir una mayor valorización en la explotación económica de los recursos algales

    Limits on the low energy antinucleon-nucleus annihilations from the Heisenberg principle

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    We show that the quantum uncertainty principle puts some limits on the effectiveness of the antinucleon-nucleus annihilation at very low energies. This is caused by the fact that the realization a very effective short-distance reaction process implies information on the relative distance of the reacting particles. Some quantitative predictions are possible on this ground, including the approximate A-independence of antinucleon-nucleus annihilation rates.Comment: 10 pages, no figure

    Studies on the mechanism of catalysis of iron-sulfur cluster transfer from IscU[2Fe2S] by HscA/HscB chaperones

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    The HscA/HscB chaperone/cochaperone system accelerates transfer of iron-sulfur clusters from the FeS-scaffold protein IscU (IscU(2)[2Fe2S], holo-IscU) to acceptor proteins in an ATP-dependent manner. We have employed visible region circular dichroism (CD) measurements to monitor chaperone-catalyzed cluster transfer from holo-IscU to apoferredoxin and to investigate chaperone-induced changes in properties of the IscU(2)[2Fe2S] cluster. HscA-mediated acceleration of [2Fe2S] cluster transfer exhibited an absolute requirement for both HscB and ATP. A mutant form of HscA lacking ATPase activity, HscA(T212V), was unable to accelerate cluster transfer, suggesting that ATP hydrolysis and conformational changes accompanying the ATP (T-state) to ADP (R-state) transition in the HscA chaperone are required for catalysis. Addition of HscA and HscB to IscU(2)[2Fe2S] did not affect the properties of the [2Fe2S] cluster, but subsequent addition of ATP was found to cause a transient change of the visible region CD spectrum, indicating distortion of the IscU-bound cluster. The dependence of the rate of decay of the observed CD change on ATP concentration and the lack of an effect of the HscA(T212V) mutant were consistent with conformational changes in the cluster coupled to ATP hydrolysis by HscA. Experiments carried out under conditions with limiting concentrations of HscA, HscB, and ATP further showed that formation of a 1:1:1 HscA-HscB-IscU(2)[2Fe2S] complex and a single ATP hydrolysis step are sufficient to elicit the full effect of the chaperones on the [2Fe2S] cluster. These results suggest that acceleration of iron-sulfur cluster transfer involves a structural change in the IscU(2)[2Fe2S] complex during the T --> R transition of HscA accompanying ATP hydrolysis

    Synchronous byzantine lattice agreement in O(log(f)) rounds

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    In the Lattice Agreement (LA) problem, originally proposed by Attiya et al. [1], a set of processes has to decide on a chain of a lattice. More precisely, each correct process proposes an element e of a certain join-semi lattice L and it has to decide on a value that contains e. Moreover, any pair pi, pj of correct processes has to decide two values deci and decj that are comparable (e.g., deci = decj or decj < deci). In this paper we present new contributions for the synchronous case. We investigate the problem in the usual message passing model for a system of n processes with distinct unique IDs. We first prove that, when only authenticated channels are available, the problem cannot be solved if f = n/3 or more processes are Byzantine. We then propose a novel algorithm that works in a synchronous system model with signatures (i.e., the authenticated message model), tolerates up to f byzantine failures (where f < n/3) and that terminates in O(log f) rounds. We discuss how to remove authenticated messages at the price of algorithm resiliency (f < n/4). Finally, we present a transformer that converts any synchronous LA algorithm to an algorithm for synchronous Generalised Lattice Agreement
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