2,598 research outputs found

    Progress in the development of an 88-mm bore 10 Tn3Sn dipole magnet

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    A 10 T, 2-layer cos(&thetas;)-dipole model magnet with an 88 mm clear bore utilizing an advanced powder-in-tube Nb3Sn conductor is being developed for the LHC. A dedicated conductor development program has resulted in a well performing Rutherford cable containing strands that uniquely exhibit both an overall current density of 600 A/mm2 @ 11 T and filaments with a diameter of 20 ¿m. The resistance between crossing strands amounts to 30-70 ¿¿ by insertion of a stainless steel core. After being exposed to a transverse pressure of 200 MPa identical cables show negligible permanent degradation of the critical current. The mechanical support structure is further optimized in order to reduce the peak stress in the mid-plane to below 130 MPa at full excitation and to control the pre-stress build-up during system assembly. Prior to the manufacturing of the final coils a dummy 2-layer pole is wound, heat-treated at 675°C and vacuum resin impregnated. This paper presents the current status of the magnet development program and highlights in particular the successful conductor developmen

    Overview of wave energy converter devices and the development of a new multi-axis laboratory prototype

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    The first part of the article provides an overview of both single-axis and multi-axis wave energy converter (WEC) technology, with a particular focus on present and past prototype devices. The second part of the article considers a multi-axis concept device that has been developed and tank tested at Lancaster University by successive Master of Engineering project teams. TALOS is a point absorber-style device, built as a 1/100th scale representation, with a solid outer hull containing all the moving parts inside. The internal power take-off system is made up of an inertial mass with hydraulic cylinders, which attach it to the hull. The mass makes up a significant proportion of the mass of the device, hence it moves around as the hull is pushed by various wave motions i.e. an inertial mass power take-off approach. The latest design has proven to be successful in wave tank testing, in that the power take-off system yields a smooth output in response to time varying inputs from the waves. An analytical model was developed to combine data from the hull model and hydraulic rig, yielding a predicted power output of up to 3.2 kW

    Understanding intra-community disparity in food and nutrition security in a generally food insecure part of eastern Africa

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    Food and nutrition insecurity continues to be one of the major development challenges in sub-Saharan Africa and other developing regions of the world. Karamoja sub-region, located in northern Uganda, is one of the poorest and most food insecure part of Eastern Africa. Previous studies have generalized the sub-region as food insecure. However, limited attention has been paid to locational differences in the food and nutrition security situation within this culturally and ecologically diverse part of the country. A crosssectional study design was used to examine at a community level, disparity in food and nutrition security situation among communities in Kotido and Moroto districts of the Karamoja sub-region. The study investigated the status of agricultural production, dietary habits and food security situation using individual household survey, focus group discussions, key informant interviews, household food insecurity access scale (HFIAS) and food insecurity coping strategy index (CSI). Data were analyzed using descriptive statistics, analysis of variance, and correlation and regression methods, at 5 % level of significance. The results showed that irrespective of ethnic differences, majority of households (78.8%) consumed less than 3 meals 24 hours preceding the interview. Generally, agricultural production was inadequate to support household food security and less than 30% of the households had adequate calorie intake. However, calorie intake adequacy was at least three (3) times higher in Kotido than in Moroto district. Plant foods were more frequently consumed than animal-source foods. At least 57% and 73% of households in Kotido and Moroto districts, respectively, never consumed fish. Food security was generally predicted by household size, ownership of food stores, occupation of household caregivers, number of livestock (especially goats) owned by households, time taken to fetch water (related to distance to water source) and sorghum production. Whereas it is generally known that Karamoja sub-region is highly food insecure, this study has demonstrated that communities in Moroto district are worse-off than those in Kotido district. Therefore, community-level characteristics ought to be an essential baseline consideration in designing food and nutrition interventions in Karamoja, and indeed in food insecure localities in general.Keywords: Karamoja, Eastern Africa, dietary practices, coping strategies, animal source food

    Vacuum production of OTFTs by vapour jet deposition of dinaphtho[2,3-b:2′,3′-f]thieno[3,2-b]thiophene (DNTT) on a lauryl acrylate functionalised dielectric surface

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    Roll-to-roll (R2R) production of organic transistors and circuits require patterned deposition of organic layers at high deposition rate. Here we demonstrate a vapour-jet process for the rapid deposition of the organic semiconductor dinaphtho[2,3-b:2',3'-f]thieno[3,2-b]thiophene (DNTT). The deposition rate achieved, equivalent to ~200 nm/s onto a stationary substrate, was several orders of magnitude faster than ordinary thermal evaporation. Nevertheless, transistor yield was 100% with an average mobility of 0.4 cm2/Vs in a single pass deposition onto a substrate moving at 0.15 m/min. We also demonstrate a vacuum, high rate R2R-compatible process for surfacefunctionalising a gate dielectric layer with lauryl acrylate which enabled an all-vacuum route to the fabrication of a five-stage ring oscillator

    NONDESTRUCTIVE EXAMINATION OF FUEL PLATES FOR THE RERTR FUEL DEVELOPMENT EXPERIMENTS

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    Nuclear fuel is the core component of reactors that is used to produce the neutron flux required for irradiation research purposes as well as commercial power generation. The development of nuclear fuels with low enrichments of uranium is a major endeavor of the RERTR program. In the development of these fuels, the RERTR program uses nondestructive examination (NDE) techniques for the purpose of determining the properties of nuclear fuel plate experiments without imparting damage or altering the fuel specimens before they are irradiated in a reactor. The vast range of properties and information about the fuel plates that can be characterized using NDE makes them highly useful for quality assurance and for analyses used in modeling the behavior of the fuel while undergoing irradiation. NDE is also particularly useful for creating a control group for post-irradiation examination comparison. The two major categories of NDE discussed in this paper are X-ray radiography and ultrasonic testing (UT) inspection/evaluation. The radiographic scans are used for the characterization of fuel meat density and homogeneity as well as the determination of fuel location within the cladding. The UT scans are able to characterize indications such as voids, delaminations, inclusions, and other abnormalities in the fuel plates which are generally referred to as debonds as well as to determine the thickness of the cladding using ultrasonic acoustic microscopy methods. Additionally, the UT techniques are now also being applied to in-canal interim examination of fuel experiments undergoing irradiation and the mapping of the fuel plate surface profile to determine fuel swelling. The methods used to carry out these NDE techniques, as well as how they operate and function, are described along with a description of which properties are characterized

    Dynamical percolation on general trees

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    H\"aggstr\"om, Peres, and Steif (1997) have introduced a dynamical version of percolation on a graph GG. When GG is a tree they derived a necessary and sufficient condition for percolation to exist at some time tt. In the case that GG is a spherically symmetric tree, H\"aggstr\"om, Peres, and Steif (1997) derived a necessary and sufficient condition for percolation to exist at some time tt in a given target set DD. The main result of the present paper is a necessary and sufficient condition for the existence of percolation, at some time tDt\in D, in the case that the underlying tree is not necessary spherically symmetric. This answers a question of Yuval Peres (personal communication). We present also a formula for the Hausdorff dimension of the set of exceptional times of percolation.Comment: 24 pages; to appear in Probability Theory and Related Field

    LpL^p-Spectral theory of locally symmetric spaces with QQ-rank one

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    We study the LpL^p-spectrum of the Laplace-Beltrami operator on certain complete locally symmetric spaces M=Γ\XM=\Gamma\backslash X with finite volume and arithmetic fundamental group Γ\Gamma whose universal covering XX is a symmetric space of non-compact type. We also show, how the obtained results for locally symmetric spaces can be generalized to manifolds with cusps of rank one

    Breaking up prolonged sitting time with walking does not affect appetite or gut hormone concentrations but does induce an energy deficit and suppresses postprandial glycaemia in sedentary adults

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    Breaking up periods of prolonged sitting can negate harmful metabolic effects but the influence on appetite and gut hormones is not understood and is investigated in this study. Thirteen sedentary (7 female) participants undertook three 5-h trials in random order: (i) uninterrupted sitting (SIT), (ii) seated with 2-min bouts of light-intensity walking every 20 min (SIT + LA), and (iii) seated with 2-min bouts of moderate-intensity walking every 20 min (SIT + MA). A standardised test drink was provided at the start of each trial and an ad libitum pasta test meal provided at the end of each trial. Subjective appetite ratings and plasma acylated ghrelin, peptide YY, insulin, and glucose were measured at regular intervals. Area under the curve (AUC) was calculated for each variable. AUC values for appetite and gut hormone concentrations were unaffected in the activity breaks conditions compared with uninterrupted sitting (linear mixed modelling: p > 0.05). Glucose AUC was lower in SIT + MA than in SIT + LA (p = 0.004) and SIT (p = 0.055). There was no difference in absolute ad libitum energy intake between conditions (p > 0.05); however, relative energy intake was lower in SIT + LA (39%; p = 0.011) and SIT + MA (120%; p < 0.001) than in SIT. In conclusion, breaking up prolonged sitting does not alter appetite and gut hormone responses to a meal over a 5-h period. Increased energy expenditure from activity breaks could promote an energy deficit that is not compensated for in a subsequent meal

    Coercive redistribution and public agreement: re-evaluating the libertarian challenge of charity

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    In this article, we evaluate the capacity of liberal egalitarianism to rebut what we call the libertarian challenge of charity. This challenge states that coercive redistributive taxation is neither needed nor justified, since those who endorse redistribution can give charitably, and those who do not endorse redistribution cannot justifiably be coerced. We argue that contemporary developments in liberal political thought render liberalism more vulnerable to this libertarian challenge. Many liberals have, in recent years, sought to recast liberalism such that it is more hospitable to cultural, religious, and ethnic diversity. This move has resulted in increased support for the claim that liberalism should be understood as a political rather than comprehensive doctrine, and that liberal institutions should draw their legitimacy from agreements made among members of an appropriately conceived deliberative community, rather than from controversial liberal principles like individual autonomy. We argue that, while this move may indeed make liberalism more compatible with cultural diversity, it also makes it more vulnerable to the libertarian challenge of charity. Not all versions of liberalism are troubled by the challenge, but those that are troubled by it are increasingly dominant. We also discuss G. A. Cohen’s claim that liberal equality requires an ‘egalitarian ethos’ and argue that, if Cohen is right, it is difficult to see how there can be an adequate response to the libertarian challenge of charity. In general, our argument can be summarised as follows: the more that liberalism is concerned accurately to model the actual democratic wishes and motivations of the people it governs, the less it is able to justify coercively imposing redistributive principles of justice
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