249 research outputs found

    Development and implementation of the verification process for the shuttle avionics system

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    The background of the shuttle avionics system design and the unique drivers associated with the redundant digital multiplexed data processing system are examined. With flight software pervading to the lowest elements of the flight critical subsystems, it was necessary to identify a unique and orderly approach of verifying the system as flight ready for STS-1. The approach and implementation plan is discussed, and both technical problems and management issues are dealt with

    The politics of the teaching of reading

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    Historically, political debates have broken out over how to teach reading in primary schools and infant classrooms. These debates and “reading wars” have often resulted from public concerns and media reportage of a fall in reading standards. They also reflect the importance placed on learning to read by parents, teachers, employers, and politicians. Public and media-driven controversies over the teaching of reading have resulted in intense public and professional debates over which specific methods and materials to use with beginning readers and with children who have reading difficulties. Recently, such debates have led to a renewed emphasis on reading proficiency and “standardized” approaches to teaching reading and engaging with literacy. The universal acceptance of the importance of learning to read has also led to vested interests in specific methods, reading programmes, and early literacy assessments amongst professional, business, commercial, and parental lobbying groups. This article traces these debates and the resulting growing support for a quantitative reductionist approach to early-reading programmes

    The ATLAS SCT Optoelectronics and the Associated Electrical Services

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    The requirements for the optical links of the ATLAS SCT are described. From the individual detector modules to the first patch panel, the electrical services are integrated with the optical links to aid in mechanical design, construction and integration. The system architecture and critical elements of the system are described. The optical links for the ATLAS SCT have been assembled and mounted onto the carbon fibre support structures. The performance of the system as measured during QA is summarised and compared to the final performance obtained after mounting modules onto the support structures

    Transport of Pb and Zn by carboxylate complexes in basinal ore fluids and related petroleum-field brines at 100°C: the influence of pH and oxygen fugacity

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    It is well established through field observations, experiments, and chemical models that oxidation (redox) state and pH exert a strong influence on the speciation of dissolved components and the solubility of minerals in hydrothermal fluids. log [Image: see text] –pH diagrams were used to depict the influence of oxygen fugacity and pH on monocarboxylate- and dicarboxylate-transport of Pb and Zn in low-temperature (100°C) hydrothermal ore fluids that are related to diagenetic processes in deep sedimentary basins, and allow a first-order comparison of Pb and Zn transport among proposed model fluids for Mississippi Valley-type (MVT) and red-bed related base metal (RBRBM) deposits in terms of their approximate pH and [Image: see text] conditions. To construct these diagrams, total Pb and Zn concentrations and Pb and Zn speciation were calculated as a function of log [Image: see text] and pH for a composite ore-brine with concentrations of major elements, total sulfur, and total carbonate that approximate the composition of MVT and RBRBM model ore fluids and modern basinal brines. In addition to acetate and malonate complexation, complexes involving the ligands Cl(-), HS(-), H(2)S, and OH(- )were included in the model of calculated total metal concentration and metal speciation. Also, in the model, Zn and Pb are competing with the common-rock forming metals Ca, Mg, Na, Fe, and Al for the same ligands. Calculated total Pb concentration and calculated total Zn concentration are constrained by galena and sphalerite solubility, respectively. Isopleths, in log [Image: see text] –pH space, of the concentration of Pb and concentration of Zn in carboxylate (acetate + malonate) complexes illustrate that the oxidized model fluids of T. H. Giordano (in Organic Acids in Geological Processes, ed. E. D. Pittman and M. D. Lewan, Springer-Verlag, New York, 1994, pp. 319–354) and G. M. Anderson (Econ. Geol., 1975, 70, 937–942) are capable of transporting sufficient amounts of Pb (up to 10 ppm) and Zn (up to 100 ppm) in the form of carboxylate complexes to form economic deposits of these metals. On the other hand, the reduced ore fluid models of D. A. Sverjensky (Econ. Geol., 1984, 79, 23–37) and T. H. Giordano and H. L. Barnes (Econ. Geol., 1981, 76, 2200–2211) can at best transport amounts of Pb and Zn, as carboxylate complexes, that are many orders of magnitude below the 1 to 10 ppm minimum required to form economic deposits. Lead and zinc speciation (mol% of total Pb or Zn) in the model ore fluid was calculated at specific log [Image: see text] –pH conditions along the 100, 0.01, and 0.001 ppm total Pb and total Zn isopleths. Along the 100 ppm isopleth conditions are oxidized (∑SO(4 )>> ∑H(2)S) with Pb and Zn predominantly in the form of chloride complexes under acid to mildly alkaline conditions (pH from 3 to approximately 7.5), while hydroxide complexes dominate Pb and Zn speciation under more alkaline conditions. Sulfide complexes are insignificant under these oxidized conditions. For more reduced conditions along the 0.01 and 0.001 ppm isopleths chloride complexes dominate Pb and Zn speciation in the SO(4)(2- )field and near the SO(4)(2-)-reduced sulfur boundary from pH = 4 to approximately 7.5, while hydroxide complexes dominate Pb and Zn speciation under alkaline conditions above pH = 7.5 in the SO(4)(2- )field. In the most reduced fluids (∑H(2)S >> ∑SO(4)) along the 0.01 and 0.001 isopleths, sulfide complexes account for almost 100% of the Pb and Zn in the model fluid. Acetate (monocarboxylate) complexation is significant only under conditions of chloride and hydroxide complex dominance and its effect is maximized in the pH range 5 to 7, where it complexes 2 to 2.6% of the total Pb and 1 to 1.25% of the total Zn. Malonate (dicarboxylate) complexes are insignificant along all isopleths. The speciation results from this study show that deep formation waters characterized by temperatures near 100°C, high oxidation states and ∑H(2)S < 0.03 mg L(-1 )([Image: see text] < 10(-6)), high chlorinities (~ 100000 mg L(-1)), and high but reasonable concentrations of carboxylate anions can mobilize up to 3% of the total Pb and up to 1.3% of the total Zn as carboxylate complexes. Furthermore, these percentages, under the most favorable conditions, correspond to approximately 1 to 100 ppm of these metals in solution; concentrations that are adequate to form economic deposits of these metals. However, the field evidence suggests that all of these optimum conditions for carboxylate complexation are rarely met at the same time. A comparison of the composite ore fluid compositions from this study and modern brine data shows that the ore brines, corresponding to log [Image: see text] –pH conditions based on the Anderson (1975) and Giordano (1994) model fluids, are similar in many respects to modern, high trace-metal petroleum-field brines. The principal differences between modern high trace-metal brines and the composite ore fluids of Anderson (1975) and Giordano (1994) relate to their carboxylate anion content. The reported concentrations of monocarboxylate anions (∑monocbx) and dicarboxylate anions (Edicbx) in high trace-metal petroleum-field brines (< 1 to 300 mg L(-1 )and < 1 mg L(-1), respectively) are significantly lower than the concentrations assumed in the modelled brines of this study (∑monocbx = 7 700 mg L(-1 )and ∑dicbx = 300 mg L(-1)). There are also major differences in the corresponding total chloride to carboxylate ratio (∑m(Cl)/∑m(cbx)) and monocarboxylate to dicarboxylate ratio (∑m(monocbx)/∑m(dicbx)). Modern high trace-metal brines have much higher ∑m(Cl)/∑m(cbx )values and, therefore, the contribution of carboxylate complexes to the total Pb and Zn content in these modern brines is likely to be significantly less than the 1 to 3 percent for the composite ore fluids of Anderson (1975) and Giordano (1994). The composite ore-brine based on the Giordano and Barnes (1981) MVT ore fluid is comparable to the high salinity (> 170 000 mg L(-1 )TDS) subset of modern brines characterized by low trace-metal content and high total reduced sulfur (∑H(2)S). A comparison of the Sverjensky (1984) composite ore-brine with modern petroleum-field brines in terms of ∑H(2)S and Zn content, reveals that this ore fluid corresponds to a "border-type" brine, between modern high trace-metal brines and those with low trace-metal content and high ∑H(2)S. A brine of this type is characterized by values of ∑H(2)S, ∑Zn, and/or ∑Pb within or near the 1 to 10 mg L(-1 )range. Based on brine-composition data from numerous references cited in this paper, border-type brines do exist but are rare. The model results and field evidence presented in this study are consistent with other chemical simulation studies of carboxylate complexation in modern petroleum-field brines. Thus, it appears that carboxylate complexation plays a minor, if not insignificant, role as a transport mechanism for Pb and Zn in high salinity Na–Cl and Na–Ca–Cl basinal brines and related ore fluids

    Sexual violence in the protracted conflict of DRC programming for rape survivors in South Kivu

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    BACKGROUND: Despite international acknowledgement of the linkages between sexual violence and conflict, reliable data on its prevalence, the circumstances, characteristics of perpetrators, and physical or mental health impacts is rare. Among the conflicts that have been associated with widespread sexual violence has been the one in the Democratic Republic of the Congo (DRC). METHODS: From 2003 till to date Malteser International has run a medico-social support programme for rape survivors in South Kivu province, DRC. In the context of this programme, a host of data was collected. We present these data and discuss the findings within the frame of available literature. RESULTS: Malteser International registered 20,517 female rape survivors in the three year period 2005-2007. Women of all ages have been targeted by sexual violence and only few of those - and many of them only after several years - sought medical care and psychological help. Sexual violence in the DRC frequently led to social, especially familial, exclusion. Members of military and paramilitary groups were identified as the main perpetrators of sexual violence. CONCLUSION: We have documented that in the DRC conflict sexual violence has been - and continues to be - highly prevalent in a wide area in the East of the country. Humanitarian programming in this field is challenging due to the multiple needs of rape survivors. The easily accessible, integrated medical and psycho-social care that the programme offered apparently responded to the needs of many rape survivors in this area

    Moving Forward in Fostering Humour: Towards Training Lighter Forms of Humour in Multicultural Contexts

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    The following theoretical position paper has the aim to outline two important future directions of humour intervention research. Firstly, existing humour trainings have not differentiated explicitly between different uses of humour or humour that may be virtuous or not. Within the realm of Positive Psychology, all virtuous forms of humour need to be identified and interventions developed that aim at fostering these benevolent/lighter forms. Secondly, most humour trainings have been adapted and conducted in one cultural context. Future trainings should consider cross-cultural perspectives to allow for comparative research and practice. Thus, the current paper first gives an overview on the extant literature on the distinction between lighter and darker forms of humour, as well as showing how humour can serve the virtues proposed by Peterson and Seligman (2004). Then, we elaborate on the findings on humour and well-being, as well as findings on existing humour interventions. The second section starts with open questions and hypotheses on how a new generation of trainings targeting lighter forms of humour could look like. Then, we discuss (potential) cultural differences in humour and how this may affect the design of interventions. When aiming for cross-cultural adaptations of the same humour program, several challenges have to be overcome, such as the term “humour” not having the same meaning in every culture, and cultural rules on what can be laughed at
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