Interoperability between WiMAX and broadband mobile space networks

In several countries manufacturers, operators, and public authorities look at WiMAX system as a viable technology to fill the "digital divide," providing broadband services mainly in suburban and rural areas, but also in densely populated areas. Nevertheless, as a standalone system it will never offer global services, and to complement its capabilities, the utilization of broadband space-based access shared among users represents a scalable and cost-effective solution to offer wider area coverage, improved performance in terms of QoS, service continuity in case of terrestrial network failure, and long-range user mobility. Integration between WiMAX and a space-based infrastructure, composed of a combination of satellites and high altitude platforms, can be pursued in several ways. The simplest solution is based on connecting a WiMAX network by means of a terrestrial network terminating at a hub station connected to the space infrastructure. A more flexible solution should allow the WiMAX subscriber station or base station to directly access the space infrastructure. This article addresses the identification of suitable scenarios and a feasibility analysis presenting link budget results related to a subset of the identified solutions

Relative price riddles in international business cycle theory: Are transport costs the explanation?

We study relative price behavior in an international business cycle model with specialization in production, in which a goods market friction is introduced through transport costs. The transport technology allows for flexible transport costs. We analyze whether this extension can account for the striking differences between theory and data as far as the moments of terms of trade and real exchange rates are concerned. We find that transport costs increase both the volatility of the terms of trade and the volatility of the real exchange rate. However, unless the transport technology is specified by a Leontief technology, transport costs do not resolve the quantitative discrepancies between theory and data. A surprising result is that transport costs may actually lower the persistence of the real exchange rate, a finding that is in contrast to much of the emphasis of the empirical literature.International business cycles, terms of trade, real exchange rates, transport costs

Use of maize silage in beef cattle feeding during the finishing period

The research investigated the use of maize silage (MS) in beef cattle diets during the finishing period by monitoring a sample of 406 commercial farms located in the Po Valley. Farms were selected in order to cover the most diverse rearing situations, in terms of farm size and cattle genotype, in which MS was fed to beef cattle during the finishing period. Each farm was visited to collect information about the feeding regimen and representative samples of total mixed ration (TMR) and MS were collected for chemical and physical analysis. Two specific classification factors of the farm population were created for statistical analysis of experimental data. The former considered the quantity of MS included in the TMR and the latter was based on the content of long particles of MS (>13 mm). Regardless of chop length, the quality of MS population was satisfactory both by a nutritional and a preservation standpoint, as indicated by the dry matter (DM) (350 ± 38 g/kg of fresh weight) and the high starch content (310 ± 28 g/kg DM) and lactic acid concentration (49 ± 12 g/kg DM). Physical analysis of MS samples showed a wide range of particle size, as result of the different chopping lengths during harvest. The average content of long particles retained by a 13-mm screen was 143 ± 73 g/kg of fresh weight. On average, MS accounted for 33.4% to the total dietary DM but a large standard deviation (11.4%) was observed across farms. The decision about the amount of MS to be included in the TMR has shown to be independent on both chemical composition and particle size of the roughage. In diets with a high quantity of MS the risk of occurrence of rumen acidosis due to the additional starch brought by this silage is balanced either by a significant reduction in the amount of other starch sources or by the higher NDF content and the coarser size of the dietary particles which should promote a prolonged rumination. The analysis of TMR particle size showed that in more than 30% of the farms MS was damaged during diet preparation with a loss of long particles. A logistic analysis demonstrated that the relative risk of MS damage was significantly increased either by a larger inclusion of the roughage in the TMR or by the use of silage with coarse particles

Performance evaluation of indoor localization techniques based on RF power measurements from active or passive devices

The performance of networks for indoor localization based on RF power measurements from active or passive devices is evaluated in terms of the accuracy, complexity, and costs. In the active device case, the terminal to be located measures the power transmitted by some devices inside its coverage area. To determine the terminal position in the area, power measurements are then compared with the data stored in an RF map of the area. A network architecture for localization based on passive devices is presented. Its operations are based on the measure of the power retransmitted from local devices interrogated by the terminal and on their identities. Performance of the two schemes is compared in terms of the probability of localization error as a function of the number (density) of active or passive devices. Analysis is carried out through simulation in a typical office-like environment whose propagation characteristics have been characterized experimentally. Considerations obtained in this work can be easily adapted to other scenarios. The procedure used for the analysis is general and can be easily extended to other situations

growth performance and behaviour of finishing beef cattle illegally treated with growth promoters

The study aimed at evaluating growth performance, feeding and social behaviour of finishing beef cattle treated with Dexamethasone per os alone or in association with Estradiol. Twenty-four French cross-bred beef bulls were allotted to 3 balanced treatment groups: Control (C); Dexamethasone (D) and Dexamethasone + Estradiol (D+E). All the bulls received the same diet and the experimental period lasted 43 days. All the productive traits and eating behaviour were similar among treatments. Bulls provided with D+E showed a prolonged rumination during the 8 h following diet distribution but this behaviour was partially performed in standing position, since lying was significantly reduced in both treated groups as compared to Control. However, difference in behaviour were too limited to be considered a reliable indicator of these illegal treatments

MEAT QUALITY FROM CHAROLAIS BULLS FED DIETS WITH DIFFERENT LEVELS OF CORN SILAGE INCLUSION

A sample of 6 intensive beef farms was selected according to the feeding plan adopted during the fattening period of Charolais bulls. Two farms did not include any corn silage in the diet (CS0), while corn silage represented 22% of the dietary DM in the second group of 2 farms (CS22), and it raised up to 44% of the dietary DM in the last 2 farms (CS44). Five bulls were randomly selected from each farm to be slaughtered in the same abattoir. Bulls age was similar across treatments but the CS44 bulls had a lower carcass weight (396 kg) than the other two treatments (436 and 446 kg for CS0 and CS22, respectively). Carcass fleshiness (SEUROP) and fatness scores were not affected by the level of corn silage in the diet. Meat quality was evaluated on a joint sample of the m. Longissimus thoracis, excised from the 5th to the 9th rib of each right half carcass 24 h post-mortem, after an ageing period of 10 d vacuum packaged at 4°C. Meat chemical analysis showed no variations in pH, DM, intramuscular fat and protein content due to the different silage inclusion in the diet. Only the cholesterol content was progressively reduced in the meat of bulls fed increasing quantities of corn silage according to a significant negative linear trend. Meat colour, cooking losses and shear force values were not affected by the diet. Therefore, based on these findings there are no substantial arguments against the use of a large amount of corn silage in the fattening diets of Charolais bulls

Analysing and Visualizing Tweets for U.S. President Popularity

In our society we are continually invested by a stream of information (opinions, preferences, comments, etc.). This shows how Twitter users react to news or events that they attend or take part in real time and with interest. In this context it becomes essential to have the appropriate tools in order to be able to analyze and extract data and information hidden in their large number of tweets. Social networks are a source of information with no rivals in terms of amount and variety of information that can be extracted from them. We propose an approach to analyze, with the help of automated tools, comments and opinions taken from social media in a real time environment. We developed a software system in R based on the Bayesian approach for text categorization. We aim of identifying sentiments expressed by the tweets posted on the Twitter social platform. The analysis of sentiment spread on social networks allows to identify the free thoughts, expressed authentically. In particular, we analyze the sentiments related to U.S President popularity by also visualizing tweets on a map. This allows to make an additional analysis of the real time reactions of people by associating the reaction of the single person who posted the tweet to his real time position in Unites States. In particular, we provide a visualization based on the geographical analysis of the sentiments of the users who posted the tweets