4,867 research outputs found

    Construction and Software Design for a Microcomputer Controlled pH/Ion Titrator

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    The construction of an automated titration device is described. The major components include an Apple II+ Microcomputer and 8-bit parallel interface. Fisher Accumet, Model 520 Digital pH/lon Meter, Gilmont Micrometer Buret of 2.5 mL capacity, Sigma stepper motor, power supply and driver to operate the buret, and a constant temperature bath of ± 0.005 °C stability. The limitations of the system are 0.001 pH/0.1 mv for the pH/ion sensing system, and 0.125 μL per step for the buret. The system as described is designed to determine equilibrium constants for metal ion-amino acid complexes. By changing the software a variety of different pH and redox titration experiments may be performed. A computer program used to operate the stepper motor driven syringe buret and record the pH from a digital pH meter is described. The program uses both Apple BASIC and assembly language. This is a closed loop operation in which the data from the pH meter is used to control the amount of reagent delivered by the buret. The results are displayed graphically as the titration proceeds. The variance of the pH readings are calculated using an assembly language subroutine and the calculations are done with zero round-off error

    Opening the Policy Window to Mobilize Action Against Corruption in the Health Sector; Comment on “We Need to Talk About Corruption in Health Systems”

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    Corruption in the health sector has been a “dirty secret” in the health policy and international development community, but recent global activities point to a day when it will no longer be neglected as a key determinant of health. To further explore next steps forward, this commentary applies the Kingdon’s multiple-streams framework (MSF) to assess what opportunities are available to mobilize the global agenda to combat health corruption. Based on this analysis, it appears that Kingdon’s problem, policy, and political streams are coalescing to create a policy window opportunity that can be leveraged based on recent developments in the global health and international development community around corruption. This includes the recent formation of the Global Network on Anti-Corruption, Transparency and Accountability (GNACTA) led by the World Health Organization (WHO), the Global Fund, and the United Nations Development Programme in 2019. It also includes bridging shared goals of addressing corruption in order to make progress towards health-specific goals in the United Nations (UN) Sustainable Development Goals (SDGs) and for achieving universal health coverage

    What Has Mathematics Done for Biology?

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    Chemical evolution of star clusters

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    I discuss the chemical evolution of star clusters, with emphasis on old globular clusters, in relation to their formation histories. Globular clusters clearly formed in a complex fashion, under markedly different conditions from any younger clusters presently known. Those special conditions must be linked to the early formation epoch of the Galaxy and must not have occurred since. While a link to the formation of globular clusters in dwarf galaxies has been suggested, present-day dwarf galaxies are not representative of the gravitational potential wells within which the globular clusters formed. Instead, a formation deep within the proto-Galaxy or within dark-matter minihaloes might be favoured. Not all globular clusters may have formed and evolved similarly. In particular, we may need to distinguish Galactic halo from Galactic bulge clusters.Comment: 27 pages, 2 figures. To appear as invited review article in a special issue of the Phil. Trans. Royal Soc. A: Ch. 6 "Star clusters as tracers of galactic star-formation histories" (ed. R. de Grijs). Fully peer reviewed. LaTeX, requires rspublic.cls style fil

    Particle Impact Analysis of Bulk Powder During Pneumatic Conveyance

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    Fragmentation of powders during transportation is a common problem for manufacturers of food and pharmaceutical products. We illustrate that the primary cause of breakage is due to inter-particle collisions, rather than particle-wall impacts, and provide a statistical mechanics model giving the number of collisions resulting in fragmentation

    Microbial and biogeochemical responses to projected future nitrate enrichment in the California upwelling system

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    Coastal California is a dynamic upwelling region where nitrogen (N) and iron (Fe) can both limit productivity and influence biogeochemistry over different spatial and temporal scales. With global change, the flux of nitrate from upwelling is expected to increase over the next century, potentially driving additional oceanic regions toward Fe limitation. In this study we explored the effect of changes in Fe/N ratio on native phytoplankton from five currently Fe-replete sites near the major California upwelling centers at Bodega Bay and Monterey Bay using nutrient addition incubation experiments. Despite the high nitrate levels (13–30 μ M) in the upwelled water, phytoplankton at three of the five sites showed increased growth when 10 μ M nitrate was added. None of the sites showed enhanced growth following addition of 10 nM Fe. Nitrate additions favored slow sinking single-celled diatoms over faster sinking chain-forming diatoms, suggesting that future increases in nitrate flux could affect carbon and silicate export and alter grazer populations. In particular, solitary cells of Cylindrotheca were more abundant than the toxin-producing genus Pseudonitzschia following nitrate addition. These responses suggest the biogeochemistry of coastal California could change in response to future increases in nitrate, and multiple stressors like ocean acidification and hypoxia may further result in ecosystem shifts

    Unitary representations of nilpotent super Lie groups

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    We show that irreducible unitary representations of nilpotent super Lie groups can be obtained by induction from a distinguished class of sub super Lie groups. These sub super Lie groups are natural analogues of polarizing subgroups that appear in classical Kirillov theory. We obtain a concrete geometric parametrization of irreducible unitary representations by nonnegative definite coadjoint orbits. As an application, we prove an analytic generalization of the Stone-von Neumann theorem for Heisenberg-Clifford super Lie groups

    Governing Noncommunicable Diseases Through Political Rationality and Technologies of Government: A Discourse Analysis

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    In the last two decades, global action to address noncommunicable diseases (NCDs) has accelerated, but policy adoption and implementation at the national level has been inadequate. This analysis examines the role of rationalities of governing, or governmentality, in national-level adoption of global recommendations. Critical discourse analysis was conducted using 49 formal institutional and organizational documents obtained through snowball sampling methodology. Text were coded using a framework of five forms of governmentality and analyzed to describe the order of discourse which has emerged within the global NCD policy domain. The dominant political rationality used to frame NCDs is rooted in risk governmentality. Recommendations for tobacco control and prevention of harmful alcohol use rely on a governmentality of police mixed with discipline. The promotion of physical activity relies heavily on disciplinary governmentality, and the prevention of unhealthy diet mixed disciplinary measures, discipline, and neoliberal governmentalities. To translate global NCD prevention and control strategies to national action, acceptability for the political rationalities embodied in policy options must be nurtured as new norms, procedures, and institutions appropriate to the political rationalities of specific interventions are developed
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