973 resultados para Refrigeration and refrigerating machinery


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Membrane-presented CD40 agonists can induce apoptosis in carcinoma, but not normal homologous epithelial cells, whereas soluble agonists are growth inhibitory but not proapoptotic unless protein synthesis is blocked. Here we demonstrate that membrane-presented CD40 ligand (CD154) (mCD40L), but not soluble agonists, triggers cell death in malignant human urothelial cells via a direct mechanism involving rapid upregulation of TNFR-associated factor (TRAF)3 protein, without concomitant upregulation of TRAF3 mRNA, followed by activation of the c-Jun N-terminal kinase (JNK)/activator protein-1 (AP-1) pathway and induction of the caspase-9/caspase-3-associated intrinsic apoptotic machinery. TRAF3 knockdown abrogated JNK/AP-1 activation and prevented CD40-mediated apoptosis, whereas restoration of CD40 expression in CD40-negative carcinoma cells restored apoptotic susceptibility via the TRAF3/AP-1-dependent mechanism. In normal human urothelial cells, mCD40L did not trigger apoptosis, but induced rapid downregulation of TRAF2 and 3, thereby paralleling the situation in B-lymphocytes. Thus, TRAF3 stabilization, JNK activation and caspase-9 induction define a novel pathway of CD40-mediated apoptosis in carcinoma cells.

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Transcription factors of the plant-specific apetala2/ethylene response factor (AP2/ERF) family control plant secondary metabolism, often as part of signalling cascades induced by jasmonate (JA) or other elicitors. Here, we functionally characterized the JA-inducible tobacco (Nicotiana tabacum) AP2/ERF factor ORC1, one of the members of the NIC2-locus ERFs that control nicotine biosynthesis and a close homologue of ORCA3, a transcriptional activator of alkaloid biosynthesis in Catharanthus roseus. ORC1 positively regulated the transcription of several structural genes coding for the enzymes involved in nicotine biosynthesis. Accordingly, overexpression of ORC1 was sufficient to stimulate alkaloid biosynthesis in tobacco plants and tree tobacco (Nicotiana glauca) root cultures. In contrast to ORCA3 in C. roseus, which needs only the GCC motif in the promoters of the alkaloid synthesis genes to induce their expression, ORC1 required the presence of both GCC-motif and G-box elements in the promoters of the tobacco nicotine biosynthesis genes for maximum transactivation. Correspondingly, combined application with the JA-inducible Nicotiana basic helix–loop–helix (bHLH) factors that bind the G-box element in these promoters enhanced ORC1 action. Conversely, overaccumulation of JAZ repressor proteins that block bHLH activity reduced ORC1 functionality. Finally, the activity of both ORC1 and bHLH proteins was post-translationally upregulated by a JA-modulated phosphorylation cascade, in which a specific mitogen-activated protein kinase kinase, JA-factor stimulating MAPKK1 (JAM1), was identified. This study highlights the complexity of the molecular machinery involved in the regulation of tobacco alkaloid biosynthesis and provides mechanistic insights about its transcriptional regulators.

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For a Digital Performing Agent to be able to perform live with a human dancer, it would be useful for the agent to be able to contextualize the movement the dancer is performing and to have a suitable movement vocabulary with which to contribute to the performance. In this paper we will discuss our research into the use of Artificial Neural Networks (ANN) as a means of allowing a software agent to learn a shared vocabulary of movement from a dancer. The agent is able to use the learnt movements to form an internal representation of what the dancer is performing, allowing it to follow the dancer, generate movement sequences based on the dancer's current movement and dance independently of the dancer using a shared movement vocabulary. By combining the ANN with a Hidden Markov Model (HMM) the agent is able to recognize short full body movement phrases and respond when the dancer performs these phrases. We consider the relationship between the dancer and agent as a means of supporting the agent's learning and performance, rather than developing the agent's capability in a self-contained fashion.

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We study the water quality in an urban district, where the surface wind distribution is an essential input but undergoes high spatial and temporal variations due to the impact of surrounding buildings. In this work, we develop an optimal sensor placement scheme to measure the wind distribution over a large urban reservoir using a limited number of wind sensors. Unlike existing solutions that assume Gaussian process of target phenomena, this study measures the wind that inherently exhibits strong non-Gaussian yearly distribution. By leveraging the local monsoon characteristics of wind, we segment a year into different monsoon seasons that follow a unique distribution respectively. We also use computational fluid dynamics to learn the spatial correlation of wind. The output of sensor placement is a set of the most informative locations to deploy the wind sensors, based on the readings of which we can accurately predict the wind over the entire reservoir in real time. Ten wind sensors are deployed. The in-field measurement results of more than 3 months suggest that the proposed sensor placement and spatial prediction scheme provides accurate wind measurement that outperforms the state-of-the-art Gaussian model based on interpolation-based approaches.

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During their autumn migratory phase, thrush nightingales (Luscinia luscinia) previously starved for 2 d were allowed to refuel under three different ambient temperature conditions (-7 degrees, 7 degrees, and 22 degrees C). During the refueling period, as well as during the preceding control and starvation periods, food intake, body mass, and feces production were monitored. In addition, daily energy expenditure was measured during the refueling period. The compilation of the energy balance during the refueling period revealed an energy density of the deposited tissue of 33.6 kJ g-1. Assuming that the deposited tissue consists of fat and protein exclusively, with energy densities of 39.6 and 5.5 kJ g-1 wet mass, respectively, we estimated the deposited tissue to consist of 82% fat and 18% wet protein (6% dry protein and 12% water). Nitrogen balances during control, starvation, and refueling phases and during a period of prolonged and complete starvation indicated that 5% of the nutrient stores consisted of dry protein. Our results support recent findings that nutrient stores for migration often contain protein in addition to fat and consequently are 15%-25% less energy rich than pure fat stores. These proteins might be stored as muscle or other functional tissue and may be required to support the extra mass of the stores and/or reflect an incapacity of the metabolic machinery to catabolize far exclusively. Fuel deposition rate was positively related with ambient temperature, whereas food intake rate was unaffected by temperature. These results indicate that the rate of fuel deposition is limited by a ceiling in food intake rate; when this ceiling is reached, fuel deposition rate is negatively affected by daily energy expenditure rate. To a certain extent, the ceiling in food intake rate varies depending on feeding conditions over the previous days. These variations in food intake capacity probably reflect the building and breakdown of gut tissues and/or gut enzyme systems and might be insensible and not evolutionary adaptive. Significant energetic costs, however, are probably associated with the maintenance of gut tissues. It is therefore feasible that changes in digestive capacity are regulated and are directed at energy economization.

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Virtual and augmented environments are often dependent on human intervention for change to occur. However there are times when it would be advantageous for appropriate human-like activity to still occur when there are no humans present. In this paper, we describe the installation art piece Recognition, which uses the movement of human participants to effect change, and the movement of a performing agent when there are no humans present. The agent's Artificial Neural Network has learnt appropriate movements from a dancer and is able to generate suitable movement for the main avatar in the absence of human participants.

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 Malaria parasites remodel erythrocytes for their survival. They passage proteins into the host cell via an export machinery known as PTEX. For the first time, this study shows that different types of parasite-exported proteins use PTEX. Importantly, new drugs can be developed which target PTEX components to eliminate an infection.

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The seafood industry has become increasingly interconnected at a global scale, with fish the most traded commodity worldwide. Travel to the farthest reaches of the oceans for capture is now common practice, and subsequent transport to market can require hundreds to thousands of miles of travel by sea and air. Refrigeration of seafood products is generally required at all stages of the journey from ocean to dinner plate, resulting in substantial energy expenditure. Energy input for aquaculture (including mariculture) products can also be high, namely due to the large amounts of feed required to support fish growth. As a result of these factors, the seafood industry has a substantial carbon footprint. Surprisingly, however, carbon footprints of seafood products are rarely integrated into assessments of their sustainability by eco-labels, sustainability certification, or consumer seafood sustainability guides. Suggestions are provided here for how carbon footprints could be incorporated within seafood sustainability schemes.

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

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This work aimed to establish the importance of maturation and ripeness stages and the use of refrigeration for the conservation of 'Paluma' guavas. Fruit picked at the mature-green and ripe stages were stored at ambient conditions (21 degrees C and 85% RH) and also at 10 degrees C (85% RH). The fruit were evaluated every 2 or 3 days for weight loss, appearance, decay, color, firmness, soluble solids, titratable acidity, ascorbic acid, total polyphenols extractable content and total antioxidant activity. The fruit stored at 21 degrees C had higher weight loss than those stored at 10 degrees C. Mature-green guavas at 21 degrees C remained in good quality for 6 days, but at 10 degrees C, the preservation period increased to 15 days. Ripe fruit were preserved for 4 days at 21 degrees C, which was extended with refrigeration to 6 days. Mature-green fruit at 21 degrees C had decay in 6 days; while at 10 degrees C decay happened in 18 days. The peel color of mature-green fruits, at 21 degrees C, showed increasing values of luminosity, indicating that its color became lighter (change from green to yellow) and at 10 degrees C it showed constant values until the end of storage. Pulp firmness of mature-green fruit declined during storage as a result of ripening. In ripe fruits such reduction occurred more slowly, since they were softer. The color of the pulp became intense red for mature fruits. Soluble solids were lower in ripe fruit at 21 degrees C, while in mature fruits at 10 degrees C, it increased. The titratable acidity increased in fruits stored at 10 degrees C. The fruits kept at 21 degrees C and the mature guavas kept at 10 degrees C showed no changes in ascorbic acid content. The ripe fruit at 10 degrees C maintained their ascorbic acid levels. Mature guavas, stored at 10 degrees C, had the longest shelf life and higher contents of soluble solids and titratable acidity, with no changes in total polyphenols extractable content and total antioxidant activity.

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The combinations of temperature and time which can cause chilling injuries in avocados 'Geada', 'Quintal' and 'Fortuna' were determined. The binomial 4 degrees C/ 28 days was selected to determine the activity of peroxidase (POD), polyphenoloxidase (PPO), polygalacturonase (PG) and methylesterase pectin (PME). The respiratory activity was also evaluated. The fruits were stored at this condition until being transferred to ambient conditions (22 degrees C and 77% RH) until maturity, when they were compared to fruits stored permanently at this environment, after being cleaned (control). In the second part of this work, different hydrothermal treatments were tested to prevent or minimize chilling injuries. Avocados 'Geada', 'Quintal' and 'Fortuna' were treated at 38 degrees C for 0, 30, 60 and 90 minutes before storage at 4 degrees C for 28 days. It was observed that the activity of enzymes associated to browning, POD and PPO, and to maturation, PG and PME, had become greater in fruits stored at 4 degrees C, or when they were transferred to environmental conditions. Fruits subjected to refrigeration, after transferred to environment, presented lower respiratory peak intensity and it occurred earlier than the others. Treatments using 38 degrees C for 60 and 90 min minimized the symptoms of chilling injury in avocados 'Geada' while for 'Quintal' the most efficient was 38 degrees C for 60 min. In 'Fortuna' these treatments did not minimize the damage by cold.

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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

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The indiscriminate management and use of soils without moisture control has changed the structure of it due to the increment of the traffic by agricultural machines through the years, causing in consequence, a soil compaction and yield reduction in the areas of intensive traffic. The purpose of this work was to estimate and to evaluate the performance of preconsolidation pressure of the soil and shear stress as indicators of changes on soil structure in fields cropped with sugarcane, as well as the impact of management processes in an Eutrorthox soil structure located in São Paulo State. The experimental field was located in Piracicaba's rural area (São Paulo State, Brazil) and has been cropped with sugarcane, in the second harvest cycle. The soil was classified by Empresa Brasileira de Pesquisa Agropecuária (EMBRAPA) [Empresa Brasileira de Pesquisa Agropecuária (EMBRAPA), 1999. Centro Nacional de Pesquisa de Solos. Sistema Brasileiro de Classificao de Solos, Empresa Brasileira de Pesquisa Agropecuária (EMBRAPA), Brasilia, 412 pp.] as an Eutrorthox. Undisturbed samples were collected and georeferenced in a grid of 60 m x 60 m from two depths: 0-0.10 m (superficial layer - SL) and in the layer of greatest mechanical resistance (LGMR), previously identified by cone index (CI). The investigated variables were pressure preconsolidation (sigma(p)), apparent cohesion (c) and internal friction angle (phi). The conclusions from the results were that the SLSC was predicted satisfactorily from up as a function of soil moisture; thus, decisions about machinery size and loading (contact pressures) can be taken. Apparent cohesion (c), internal friction angle (phi) and the Coulomb equation were significantly altered by traffic intensity. The sigma(p), c and phi maps were shown to be important tools to localize and visualize soil compaction and mechanical resistance zones. They constitute a valuable resource to evaluate the traffic impact in areas cropped with sugarcane in State of São Paulo, Brazil. (C) 2008 Elsevier B.V. All rights reserved.

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The fuel cell is an emerging cogeneration technology that has been applied successfully in Japan, the USA and some countries in the European Union. This system performs direct conversion of the chemical energy of the oxidation of hydrogen from fuel with atmospheric oxygen into direct current electricity and waste heat via an electrochemical process relying on the use of different electrolytes (phosphoric acid, molten carbonate and solid oxide, depending on operating temperature). This technology permits the recovery of waste heat, available from 200 degreesC up to 1000 degreesC depending on the electrolyte technology, which can be used in the production of steam, hot or cold water, or hot or cold air, depending on the associated recuperation equipment. In this paper, an energy, exergy and economic analysis of a fuel cell cogeneration system (FCCS) is presented. The FCCS is applied in a segment of the tertiary sector to show that it is a feasible alternative for rational decentralized energy production under Brazilian conditions. The technoeconomic analysis shows a global efficiency or fuel utilization efficiency of 86%. Analysis shows that the exergy losses in the fuel cell unit and the absorption refrigeration system are significant. Furthermore, the payback period estimated is about 3 and 5 years for investments in fuel cells of 1000 and 1500 US$/kW, respectively. (C) 2001 Elsevier B.V. Ltd. All rights reserved.

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A novel single-phase voltage source rectifier capable to achieve High-Power-Factor (HPF) for variable speed refrigeration system application, is proposed in this paper. The proposed system is composed by a single-phase high-power-factor boost rectifier, with two cells in interleave connection, operating in critical conduction mode, and employing a soft-switching technique, controlled by a Field Programmable Gate Array (FPGA), associated with a conventional three-phase IGBT bridge inverter (VSI - Voltage Source Inverter), controlled by a Digital Signal Processor (DSP). The soft-switching technique for the input stage is based on zero-current-switching (ZCS) cells. The rectifier's features include the reduction in the input current ripple, the reduction in the output voltage ripple, the use of low stress devices, low volume for the EMI input filter, high input power factor (PF), and low total harmonic distortion (THD) in the input current, in compliance with the EEC61000-3-2 standards. The digital controller for the output stage has been developed using a conventional voltage-frequency control (scalar V/f control), and a simplified stator oriented Vector control, in order to verify the feasibility and performance of the proposed digital controls for continuous temperature control applied at a refrigerator prototype.