1,598 research outputs found

    General education in the royal air force 1910 - 1961

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    Effects of Growth Pattern on Muscle Growth, Nuclei Number, Protein Accretion, and Body Composition in Heifers

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    The effects of compensatory growth on accretion of muscle mass, protein mass, and nuclei number of the supraspinatus and semitendinosus muscles were evaluated using seven serial slaughter groups of Angus x Limousin heifer calves (n = 28, BW 270 2 9.5 kg). Fractional growth rates of carcass protein and fat were also evaluated. To achieve compensatory growth, energy intake was restricted for 88 days (Phase 1) followed by adlibitum feeding of a high energy diet (Phase2) [LH]. Controls were allowed continuous ad libitum access to the high energy diet (HH). Muscle weights, body composition samples, and muscle biopsies were collected at various weight (465 vs 500 kg) or age (88 vs 186 days) constants. Phase 1 energy restriction limited body weight, carcass weight, carcass protein mass, and carcass fat mass (P\u3c.05). This was the result of the limited tissue fractional growth rates. The fractional growth rate of protein for heifers exhibiting compensatory growth was not increased but was maintained until maximum carcass protein mass was attained. Maximum carcass protein mass was attained by a weight of 465 kg. Any further increase in carcass weight was primarily attributed to an increase of carcass fat mass regardless of previous management. Energy restriction limited muscle, protein, and nuclei accretion rates. Heifers exhibiting compensatory growth sustained a linear growth potential until maximum muscle mass occurred at an end point similar to cattle not exhibiting compensatory growth. Muscle nuclei maintained a constant relationship to muscle mass independent of nutritional treatment, muscle type (supraspinatus vs semitendinosus), or days on feed. These data indicate compensatory growth alters the growth curve without affecting the mechanisms of growth

    Water use and water availability constraints to decarbonised electricity systems

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    Analysis of numerous low carbon electricity strategies have been shown to have very divergent water requirements, normally needed for cooling of thermoelectric power stations. Our regional river-basin scale analysis of water use for future UK electricity strategies shows that, whilst in the majority of cases freshwater use is expected to decline, pathways with high levels of carbon capture and storage (CCS) will result in significantly elevated and concentrated water demands in a few key river basins. Furthermore, these growing demands are compared to both current water availability, and our expected regional water availability under the impacts of climate change. We identify key freshwater constraints to electricity strategies with high levels of CCS and show how these risks may be mitigated with higher levels of hybrid cooling and alternative cooling water sources

    The Dynamics of Internet Traffic: Self-Similarity, Self-Organization, and Complex Phenomena

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    The Internet is the most complex system ever created in human history. Therefore, its dynamics and traffic unsurprisingly take on a rich variety of complex dynamics, self-organization, and other phenomena that have been researched for years. This paper is a review of the complex dynamics of Internet traffic. Departing from normal treatises, we will take a view from both the network engineering and physics perspectives showing the strengths and weaknesses as well as insights of both. In addition, many less covered phenomena such as traffic oscillations, large-scale effects of worm traffic, and comparisons of the Internet and biological models will be covered.Comment: 63 pages, 7 figures, 7 tables, submitted to Advances in Complex System

    Cubic Curves, Finite Geometry and Cryptography

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    Some geometry on non-singular cubic curves, mainly over finite fields, is surveyed. Such a curve has 9,3,1 or 0 points of inflexion, and cubic curves are classified accordingly. The group structure and the possible numbers of rational points are also surveyed. A possible strengthening of the security of elliptic curve cryptography is proposed using a `shared secret' related to the group law. Cubic curves are also used in a new way to construct sets of points having various combinatorial and geometric properties that are of particular interest in finite Desarguesian planes.Comment: This is a version of our article to appear in Acta Applicandae Mathematicae. In this version, we have corrected a sentence in the third paragraph. The final publication is available at springerlink.com at http://www.springerlink.com/content/xh85647871215644

    Sexual exploitation in children: Nature, prevalence and distinguishing characteristics reported in young adulthood

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    The aim of this study was to explore the nature and extent of sexual exploitation in a university student sample, whilst being clear that sexual exploitation is sexual abuse. Overall, 47% of participants (96 out of 204) reported having been approached by an adult in a sexual manner when they were under the age of 16. The study predicted that a number of individual characteristics would increase a young person’s vulnerability for sexual exploitation. These included low self-esteem, external locus of control, social loneliness and insecure attachment. Results indicated lower levels of self-esteem among those who had been approached sexually, although it is not clear in terms of causality. There were no differences in scores for locus of control or loneliness. Relationship anxiety was significantly linked with children having engaged in sexual behaviours with an adult. The implications of these findings are discussed in terms of emerging individual characteristics relating to a risk of sexual exploitation

    Collective Decision Dynamics in the Presence of External Drivers

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    We develop a sequence of models describing information transmission and decision dynamics for a network of individual agents subject to multiple sources of influence. Our general framework is set in the context of an impending natural disaster, where individuals, represented by nodes on the network, must decide whether or not to evacuate. Sources of influence include a one-to-many externally driven global broadcast as well as pairwise interactions, across links in the network, in which agents transmit either continuous opinions or binary actions. We consider both uniform and variable threshold rules on the individual opinion as baseline models for decision-making. Our results indicate that 1) social networks lead to clustering and cohesive action among individuals, 2) binary information introduces high temporal variability and stagnation, and 3) information transmission over the network can either facilitate or hinder action adoption, depending on the influence of the global broadcast relative to the social network. Our framework highlights the essential role of local interactions between agents in predicting collective behavior of the population as a whole.Comment: 14 pages, 7 figure

    Fluctuation-driven capacity distribution in complex networks

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    Maximizing robustness and minimizing cost are common objectives in the design of infrastructure networks. However, most infrastructure networks evolve and operate in a highly decentralized fashion, which may significantly impact the allocation of resources across the system. Here, we investigate this question by focusing on the relation between capacity and load in different types of real-world communication and transportation networks. We find strong empirical evidence that the actual capacity of the network elements tends to be similar to the maximum available capacity, if the cost is not strongly constraining. As more weight is given to the cost, however, the capacity approaches the load nonlinearly. In particular, all systems analyzed show larger unoccupied portions of the capacities on network elements subjected to smaller loads, which is in sharp contrast with the assumptions involved in (linear) models proposed in previous theoretical studies. We describe the observed behavior of the capacity-load relation as a function of the relative importance of the cost by using a model that optimizes capacities to cope with network traffic fluctuations. These results suggest that infrastructure systems have evolved under pressure to minimize local failures, but not necessarily global failures that can be caused by the spread of local damage through cascading processes
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