Pneumatic system for controlling and actuating pneumatic cyclic devices

Pneumatic system for cyclic control of fluid flow in pneumatic devic

Spool valve cycles at controlled frequency

Spool valve accurately controls the cycle of a pneumatically-actuated system over long periods. Regulation of pressure from the external source, positioning of the adjusting plugs, and magnet selection, together afford wide variation in cyclic timing and speed of closure in either direction

Competition between Pressure and Gravity Confinement in Lyman-Alpha Forest Observations

A break in the distribution function of Ly$\alpha$ clouds (at a typical redshift of $2.5$) has been reported by Petitjean et al. (1993). This feature is what would be expected from a transition between pressure confinement and gravity confinement (as predicted in Charlton, Salpeter, and Hogan (1993)). The column density at which the feature occurs has been used to determine the external confining pressure, $\sim 10 {\rm cm}^{-3} {\rm K}$, which could be due to a hot, intergalactic medium. For models that provide a good fit to the data, the contribution of the gas in clouds to $\Omega$ is small. The specific shape of the distribution function at the transition (predicted by models to have a non-monotonic slope) can serve as a diagnostic of the distribution of dark matter around Ly$\alpha$ forest clouds, and the present data already eliminate certain models.Comment: 10 pages plain TeX, 2 figures available upon request, submitted to ApJ Letters, PSU-jc-

The Revealing Dust: Mid-Infrared Activity in Hickson Compact Group Galaxy Nuclei

We present a sample of 46 galaxy nuclei from 12 nearby (z<4500 km/s) Hickson Compact Groups (HCGs) with a complete suite of 1-24 micron 2MASS+Spitzer nuclear photometry. For all objects in the sample, blue emission from stellar photospheres dominates in the near-IR through the 3.6 micron IRAC band. Twenty-five of 46 (54%) galaxy nuclei show red, mid-IR continua characteristic of hot dust powered by ongoing star formation and/or accretion onto a central black hole. We introduce alpha_{IRAC}, the spectral index of a power-law fit to the 4.5-8.0 micron IRAC data, and demonstrate that it cleanly separates the mid-IR active and non-active HCG nuclei. This parameter is more powerful for identifying low to moderate-luminosity mid-IR activity than other measures which include data at rest-frame lambda<3.6 micron that may be dominated by stellar photospheric emission. While the HCG galaxies clearly have a bimodal distribution in this parameter space, a comparison sample from the Spitzer Nearby Galaxy Survey (SINGS) matched in J-band total galaxy luminosity is continuously distributed. A second diagnostic, the fraction of 24 micron emission in excess of that expected from quiescent galaxies, f_{24D}, reveals an additional 3 nuclei to be active at 24 micron. Comparing these two mid-IR diagnostics of nuclear activity to optical spectroscopic identifications from the literature reveals some discrepancies, and we discuss the challenges of distinguishing the source of ionizing radiation in these and other lower luminosity systems. We find a significant correlation between the fraction of mid-IR active galaxies and the total HI mass in a group, and investigate possible interpretations of these results in light of galaxy evolution in the highly interactive system of a compact group environment.Comment: 20 pages, 17 figures (1 color), uses emulateapj. Accepted for publication by Ap

Prevalence of household food poverty in South Africa: results from a large, nationally representative survey

Household food insecurity is a major determinant of undernutrition, yet there is little information on its prevalence in the South African population. This paper assesses household food insecurity in South Africa using a quantitative and objective measure, known as food poverty, and provides prevalence estimates by geographic area and socio-economic condition. Secondary data analysis combining two sources: Statistics South Africa's household-based 1995 Income and Expenditure Survey; and the University of Port Elizabeth's Household Subsistence Level series, a nationally-conducted, market-based survey. South Africa. A nationally representative sample of the entire country – stratified by race, province, and urban and non-urban areas – consisting of 28 704 households. A household is defined to be in food poverty when monthly food spending is less than the cost of a nutritionally adequate very low-cost diet. The prevalence of food poverty in South Africa in 1995 was 43%. Food poverty rates were highest among households headed by Africans, followed by coloureds, Indians and whites. Higher food poverty rates were found with decreasing income, increasing household size, and among households in rural areas or those headed by females. The widespread nature of household food insecurity in South Africa is documented here. Prevalence rates by geographic and socio-economic breakdown provide the means for targeting of nutritional interventions and for monitoring progress in this field. The corroboration of these findings with both internal validation measures and external sources suggests that food poverty is a useful, objective measure of household food insecurity

The Development Round of Trade Negotiations in the Aftermath of Cancun: A report for the Commonwealth Secretariat

The development focus of the Doha Round emerged from a renewed spirit of responsibility for the challenges faced by poor countries and the perceived inequities generated by previous rounds of trade negotiations. This study presents an alternative way forward for the Doha Round based on principles of social justice and economic analysis. It looks at the trade negotiation agenda from the perspective of first principles, presenting prodevelopment priorities that should form the core of the Doha Round agreements if there is to be widespread support for the continuing agenda for trade reform and liberalization

Common Values for the Development Round

In this paper we make a contribution to this debate by considering several fundamental questions: What are the appropriate boundaries for the agenda of the WTO? What would constitute a "fair" agreement? What are the characteristics of a "fair" negotiating process? There are no universal answers to these questions, but there are answers that derive legitimacy from commonly agreed values implemented in a democratic process. This paper presents a set of values with a Rawlsian flavor, which we believe is consistent with the development focus of this round and a concern for social justice. In some cases we make the implications of these principles for the outcome of the negotiations explicit, however in most cases we refer the reader to more detailed discussion in Stiglitz and Charlton (2004). Note: The opinions expressed in these papers represent those of the author(s) and not The Initiative for Policy Dialogue. These papers are unpublished and have not been peer reviewed. Please do not cite without explicit permission from the author(s)