Steady-state entanglement between distant quantum dots in photonic crystal dimers

We show that two spatially separated semiconductor quantum dots under resonant and continuous-wave excitation can be strongly entangled in the steady-state, thanks to their radiative coupling by mutual interaction through the normal modes of a photonic crystal dimer. We employ a quantum master equation formalism to quantify the steady-state entanglement by calculating the system {\it negativity}. Calculations are specified to consider realistic semiconductor nanostructure parameters for the photonic crystal dimer-quantum dots coupled system, determined by a guided mode expansion solution of Maxwell equations. Negativity values of the order of 0.1 ($20\%$ of the maximum value) are shown for interdot distances that are larger than the resonant wavelength of the system. It is shown that the amount of entanglement is almost independent of the interdot distance, as long as the normal mode splitting of the photonic dimer is larger than their linewidths, which becomes the only requirement to achieve a local and individual qubit addressing. Considering inhomogeneously broadened quantum dots, we find that the steady-state entanglement is preserved as long as the detuning between the two quantum dot resonances is small when compared to their decay rates. The steady-state entanglement is shown to be robust against the effects of pure dephasing of the quantum dot transitions. We finally study the entanglement dynamics for a configuration in which one of the two quantum dots is initially excited and find that the transient negativity can be enhanced by more than a factor of two with respect to the steady-state value. These results are promising for practical applications of entangled states at short time scales.Comment: 10 pages, 7 figure

Modelação estatística dos índices de sinistralidade, aplicados ao setor da construção

Face ao quadro problemático das estatísticas de sinistralidade e considerando a Segurança na construção uma missão vital e de primordial significado para a sociedade, pretendeu-se com o presente estudo desenvolver modelos matemáticos, com capacidade explicativa do comportamento dos índices de sinistralidade em função de variáveis setoriais e globais como a taxa de desemprego e a taxa de crescimento do PIB de Portugal. Foram utilizados dados oficiais relativos a uma amostra de conveniência composta por 58 empresas do setor da construção, referente ao período de 6 anos. Foi efetuado o tratamento estatístico dos dados e desenhados modelos com base em regressões lineares. No final, dois dos modelos desenvolvidos apresentaram capacidade explicativa. Sendo que nestes aparecem como variáveis relevantes, a taxa de desemprego e os custos de formação por trabalhador. Apesar da capacidade explicativa dos modelos e da possibilidade da sua utilização pelas empresas do setor, como ferramenta potenciadora da Prevenção dos acidentes ocupacionais, é ainda questionada a eventual falta de consistência dos dados e a qualidade da formação ministrada nas empresas

Developing a set of strategies, in Portugal, to monitor and prevent damages in animal housing, due to hot climate conditions

In Portugal, animal production (mainly meat and milk) represents 32% of the Agriculture Domestic Product and, in some regions, its socio-economic importance is quite relevant. Located in Southwestern Europe, Portugal has a mediterranean climate: Winter is cold and wet. Summer is hot and dry particularly in Alentejo and northeastern regions. Significantly high temperatures combined with dry air (or even wet air) may bring about serious problems or damage to livestock and losses to the farmer. In Portugal, it is estimated that 20% of the annual losses in animal production are due to adverse climatic factors or deficient regulation in indoor climatization of animal housing. The situation is most problematic in summer when very high temperatures occur. According to the HWDI (Heat Wave Duration Index) since 2000, in Portugal three heat waves have occurred, with temperatures over 40 degrees C. Generally, in all regions, these periods of very high temperatures are combined with dry air (low relative humidity). In most cases, the buildings are not suitable for animal housing under high temperatures. They lack appropriate equipment to control indoor environmental conditions. To minimize the effects of these adverse climatic situations on animal production, in Portugal, we intend to carry out a work project to tackle this problem. For that purpose, we intend to develop a set of strategies aiming at: - collecting information about animal breeding and animal housing; - identifying the climatic factors that affect livestock, in all portuguese regions; - evaluating the effects of the climatic factors on animal production, in different regions; - studying strategies and methods to help farmers cope with the problem; - establishing a web page to spread information; To carry out this work we have to organize a multidisciplinary team in order to embrace all different fields of interest related to this problem

Strategies to minimize effects of hot climate conditions on livestock in Portugal. A regional approach

In Portugal, animal production is of major significance, both economically and socially. Livestock are especially important to those regions in which agriculture is the main economic activity. Situated in Southwestern Europe, Portugal has a Mediterranean climate with hot and dry Summer. Livestock farmers have to deal with high temperatures and with their effects on animal production. In most cases, breeders are not prepared to handle animals under high temperatures; they lack facilities and/or knowledge about this problem. We have begun work with the aim of developing strategies to monitor and prevent harm to animals (housed or raised outdoors) during the summer months. We need to identify the Portuguese regions most seriously affected by this problem, as well as where and for how long high temperatures occur most frequently. Both individual days with very high temperatures and heat waves are becoming more and more common in Portugal. The past four summers have been among the hottest ever registered. Since 2003, eight heat waves have occurred. We chose two locations in Portugal's Northeast to carry out a preliminary study in order to evaluate the occurrence of hot climate conditions in recent years; to develop methods of obtaining that data; and to learn how climatic factors (mainly temperature) evolve over the course of the summer. We can conclude that in this region livestock are commonly exposed to high temperatures for long periods. It becomes clear that it is necessary to develop strategies to protect animals from the effects of such conditions

Monitorização, prevenção, comunicação e resolução dos riscos climáticos no sector pecuário. Estabelecimento de estratégias de implementação de um serviço de alerta e de combate ao problema

Na Europa do Sul ou nas regiões mediterrâneas, as temperaturas muito elevadas podem provocar dificuldades e danos na produção animal e aos produtores. Os fenómenos de ondas de calor ou de temperaturas muito elevadas, causam prejuízos avultados e perdas significativas na produção animal. Em Portugal, verificamos que são cada vez mais frequentes a ocorrência de situações com condições climáticas adversas, devidas a períodos de temperaturas elevadas. Verificaram-se, também, diversas ondas de calor, de acordo com o HWDI (Heat Wave Duration Index). Atendendo a estas questões e porque as ondas de calor coincidem com algumas regiões do país onde estão concentradas as actividades de produção animal, estamos a desenvolver um trabalho que pretende estudar e acompanhar estes fenómenos, no intuito de minimizar o seu impacto nas explorações pecuárias. Pretende-se identificar os factores climáticos que, nas diferentes regiões, podem afectar os animais; identificar a diversidade climática em cada região; avaliar os efeitos diferenciados da diversidade climática na produção animal. Para isso, preparou-se um conjunto de medidas e estratégias, envolvendo um trabalho interdisciplinar, para fazer face a este problema. In the South of Europe or mediterranean regions, significant high temperatures combined with dry air (or even wet air) may produce serious problems or damages to livestock and to the farmer. To understand and minimize the effects of this situation in Portugal, we intend to carry out a work project aiming to identify the climatic factors that affect livestock in all portuguese regions; the climatic diversity of the several regions; to evaluate the effects of the climatic factors in livestock; and to develop strategies to face these problems

Performance Assessment of ESP8266 Wireless Mesh Networks

This paper presents a wireless mesh network testbed based on ESP8266 devices using painlessMesh library. It evaluates its feasibility and potential effectiveness as a solution to monitor perishable goods, such as fresh fruit and vegetables, which are often stored and transported inside refrigerated containers. Performance testing experiments with different numbers of nodes and traffic loads and different message payload sizes are conducted under unicast transmission. The impact on network performance is evaluated in terms of delivery ratio and delivery delay, which, consequently, affect the energy consumption and, hence, network lifetime. The results of this investigation are an important contribution to help researchers to propose mechanisms, schemes, and protocols to improve performance in such challenging networks.info:eu-repo/semantics/publishedVersio

Diurnal Variation in Forage Nutrient Composition and Metabolic Parameters of Horses Grazing Warm-Season, Perennial Grass-Legume Mixed Pastures

Although warm-season, grass-legume mixed pastures have improved nutritive value and may reduce negative environmental impacts relative to nitrogen-fertilized grass monocultures, no study has been done to evaluate their effect on diurnal variation of non-structural carbohydrates (NSC) and other nutrients, and on the metabolic responses observed in horses’ blood and fecal samples. This 2-yr study aimed to investigate the circadian variation in nutrient composition and the fecal and blood metabolic responses in horses grazing these pastures. Forage, fecal, and blood samples were collected every 28 days at 0600, 1200, 1800, and 0000 h, in two years, for measurement of diurnal variation in forage nutrient composition and fecal and blood metabolites. Forage nutrient composition was affected by time of the day, with digestible energy (DE) and NSC increasing at 1800 h, crude protein decreasing after 1200 h and the fiber components increasing at 1200 h. Fecal lactate and blood insulin were also affected by time of the day. Fecal lactate increased from 0600 to 1200 h. Insulin levels were greater at 1800 than at 0600 h. The increased insulin level followed the increased concentration of NSC in the forage. In conclusion, warm-season, grass-legume mixed pastures show a diurnal pattern in forage nutrient composition, with increased NSC later in the afternoon. However, the metabolic responses observed in this study were not sufficient to predispose horses to metabolic dysregulation. The results also indicate that restricting grazing to the morning may reduce the forage nutritive value, with decreased concentration of DE and increased concentrations of the fiber components, which may decrease diet digestibility

Herbage Responses and Performance of Mature Horses Grazing Warm-Season Perennial Grass-Legume Mixed Pastures

Legume-grass mixtures may be a useful alternative to nitrogen-fertilized grass monocultures, but pasture and animal responses have not been assessed for pastures grazed by horses in Florida. This 2-yr study compared pasture and horse responses of continuously stocked, mixed pastures of rhizoma peanut (RP, Arachis glabrata Benth) and bahiagrass (BG, Paspalum notatum Flüggé) receiving 30 kg nitrogen (N)/ha (RP-BG) compared with BG pastures fertilized with 120 kg/N ha (BG-N) or with no N (BG-No N). Herbage mass was similar among treatments in 2020 and for most evaluation days in 2019. In 2019, stocking rate (AU/ha) was greater in BG-N (3.9) than in RP-BG (3.7) and BG-No N (3.1). In 2020, BG-No N (2.6) had the lesser stocking rate compared with BG-N (2.9) and RP-BG (2.9), with RP-BG not differing from BG-N. Herbage crude protein (CP) and digestible energy were similar across treatments in 2020, but they were greater for BG-N and RP-BG than BG-No N at some evaluation days in 2019. Except for CP, treatment did not affect nutrient digestibility by horses. Digestibility of CP was greatest for RP-BG in the late season. In the RP-BG treatment, proportion of RP in the pasture (~29%) was not affected by sampling date, and RP comprised 18.4% of the diet. Nonetheless, no differences were observed among treatments for body weight and condition score. The results indicate that intercropping legumes into warm-season perennial pastures can improve some measures of nutritive value and maintain horses’ body condition with similar stocking rate as N-fertilized bahiagrass pastures, while contributing to development of sustainable grazing systems for horses with reduced off-farm nitrogen inputs

Assessment of polymeric flow in micromouldings coated with nanocrystalline diamond

With the increased production of microcomponents, it is necessary to overcome various technological challenges existing in the micro-injection moulding process: the wear of the microfeatured moulding tool; the perfect filling of high aspect ratio paths; the rheology and heat transfer mechanism in such conditions; among other factors. To address some of these challenges, appropriate moulding surface coatings, displaying high hardness, high thermal conductivity, high thermal shock capacity and low friction coefficient may be of great importance. In this work, a moulding insert was coated with nanocrystalline diamond films. This insert, especially designed to evaluate the flow front of two pathways, was then used for the production of polypropylene microparts with the scope of analysing the relative position of the welding line, and therefore, evaluate the polymeric melt flow in the microimpressions. The morphology, quality and stress developed in the obtained diamond film was analysed, showing an average grain size of about 100 nm, in which their crystals are homogeneous, forming a coalescent film. The coatings present a typical Raman spectrum. Through the moulding path with the diamond coating, it was found that the melt temperature is the variable that has the greatest influence on the advance of the front flow. The front flow appears to benefit from the coating, leading to a more controlled filling process, replicating the findings presented formerly. It is suggested that the diamond coating can act as a heat buffer, weakening the heat transfer mechanism in the polymer/ mould interface at the flow stage, reducing the importance of the design of the temperature control system

An Eco-Energetic performance comparison of dehumidification systems in High-Moisture indoor environments

This study discusses the choice of dehumidification systems for high-moisture indoor environments, such as indoor swimming pools, supported by an eco-energetic performance comparison. Initially, the causes of the high relative humidity and condensation in these spaces are reported, as well as the available dehumidification technologies. Two different solutions are described: desiccant wheel dehumidification and re-cooling. The energy demand required by a refrigeration system is lower than the desiccant wheel; however, the former system requires less maintenance and does not require refrigerant fluid. An eco-energetic comparison is performed between the two systems in two countries with different energy matrices (Brazil and USA). In Brazil, the desiccant wheel is the best choice for the past 10 years, with a predicted 351,520 kgCO2 of CO2 emissions, which is 38% lower than the refrigeration system. In the USA, the best option is the refrigeration system (1,463,350 kgCO2), a 12% more efficient option than desiccant wheels. This model can be considered for energy and CO2 emissions assessment, predicting which system has better energy efficiency and lower environmental impact, depending on the refrigerant type, location and environmental conditions.info:eu-repo/semantics/publishedVersio