Optimal Light Beams and Mirror Shapes for Future LIGO Interferometers

We report the results of a recent search for the lowest value of thermal noise that can be achieved in LIGO by changing the shape of mirrors, while fixing the mirror radius and maintaining a low diffractional loss. The result of this minimization is a beam with thermal noise a factor of 2.32 (in power) lower than previously considered Mesa Beams and a factor of 5.45 (in power) lower than the Gaussian beams employed in the current baseline design. Mirrors that confine these beams have been found to be roughly conical in shape, with an average slope approximately equal to the mirror radius divided by arm length, and with mild corrections varying at the Fresnel scale. Such a mirror system, if built, would impact the sensitivity of LIGO, increasing the event rate of observing gravitational waves in the frequency range of maximum sensitivity roughly by a factor of three compared to an Advanced LIGO using Mesa beams (assuming all other noises remain unchanged). We discuss the resulting beam and mirror properties and study requirements on mirror tilt, displacement and figure error, in order for this beam to be used in LIGO detectors.Comment: 9 pages, 11 figure

Building Community Partnerships in Support of a Postsecondary Completion Agenda

This report highlights key lessons from the Bill & Melinda Gates Foundation's Community Partnerships portfolio evaluation. It assesses the communities' progress over the course of the investment, and describes their work in the areas of building public commitment, using data, building and sustaining partnerships, and aligning policies and practices. The OMG Center served as the national evaluator of this initiative and the report also discusses the steps these communities can take to sustain their programs

A review of social protection in Latin America

This paper reviews social protection trends and policy responses in Latin America as part of a global scoping study on social protection commissioned by Ford Foundation (See Appendix One for ToR for this paper). The paper is organised as follows (following the paper contents as described in Appendix One): Section 1 identifies the main trends in poverty and vulnerability in the region, with particular references to rural-urban and life course poverty incidence. Section 2 provides a review of social protection trends. It discusses the two main areas of change and innovation in the last two decades: the reform of social insurance provision and the rapid expansion of social assistance schemes. Section 3 identifies some potential points of engagement between Ford Foundation work and the social protection policy agenda in the region

Thermal distortions of non-Gaussian beams in Fabry–Perot cavities

Thermal effects are already important in currently operating interferometric gravitational wave detectors. Planned upgrades of these detectors involve increasing optical power to combat quantum shot noise. We consider the ramifications of this increased power for one particular class of laser beams—wide, flat-topped, mesa beams. In particular we model a single mesa beam Fabry–Perot cavity having thermoelastically deformed mirrors. We calculate the intensity profile of the fundamental cavity eigenmode in the presence of thermal perturbations, and the associated changes in thermal noise. We also outline an idealized method of correcting for such effects. At each stage we contrast our results with those of a comparable Gaussian beam cavity. Although we focus on mesa beams the techniques described are applicable to any azimuthally symmetric system

The Gender Dimensions of Pension Systems: Policies and Constraints for the Protection of Older Women

This paper documents the pervasiveness of women's lack of income security in old age across a large number of countries, but also points to a number of important policy measures that can be taken to address gender pension gaps. It focuses on how pension systems interact with other social and labour market conditions over women's life courses to increase or decrease gender inequalities in old age. It reviews pension systems to pinpoint the key sources of gender inequality in they way they are structured. The paper shows that crucial policy choices for the protection of women must take into account the conditions for entitlements in pension systems, the types of transfers that are promoted between women and men, the policy tools available to offset gender differences in paid work, earnings and unpaid work and the protection of the most vulnerable social groups through redistributive benefits. The paper concludes with some recommendations to make pension systems more gender equitable and suggests that policies aimed at achieving gender equality in pension rights and benefits need to work on several complementary fronts (including measures regarding pension system design, but also labour market regulation and the reconciliation of work and family life) and consider the diversity of women's situation across social strata as well as across countries. This paper was produced for UN Women's flagship report Progress of the World's Women 2015-2016 to be released as part of the UN Women discussion paper series

Response of Fresh Food Suppliers to Sustainable Supply Chain Management of Large European Retailers

This article analyses new supply chain management (SCM) strategies of the largest retail distribution chains in Europe within the context of differing sustainability concepts and approaches. An analysis is carried out of the strategic plans of such retailers, as well as recent developments in the sector. We begin by identifying the priority actions of retailers and then evaluating, by means of a survey, how small horticultural marketing firms (mainly cooperatives) in southeast Spain respond to the needs of these retailers. Subsequently, an analysis is carried out on these small marketing firm exporters to identify the relative weight which they assign to the variables assessed, while also considering the existing relationships between said weighted variables and business profits. Our results show that retailers tend to establish more simplified supply chains (that is, shorter and more vertical), essentially demonstrating their interpretation of a sustainable supply chain. In contrast, horticultural marketing firms have concentrated more on tactical and operational issues, thereby neglecting environmental, social and logistics management. Thus, their success rate in meeting the sustainability demands of their customers can be considered medium-low, requiring a more proactive attitude. Improved and collaborative relations, and the integration of sustainability concepts between suppliers (marketing firms) and their clients could contribute to successfully meeting sustainability demands. From the point of view of the consumer, close supplier–retail relationships have solved food safety issues, but the implementation of sustainability in other supply chain activities and processes is a pending issue. We propose strategic approximation and collaboration to bridge the gap between the varying sustainability demands in the supplier–retail relationship within perishable supply chains. Although this article specifically addresses fresh vegetable supply chains, the results may be extrapolated to other agri-food chains with a similar structure

Ge-on-Si single-photon avalanche diode detectors: design, modeling, fabrication, and characterization at wavelengths 1310 and 1550 nm

The design, modeling, fabrication, and characterization of single-photon avalanche diode detectors with an epitaxial Ge absorption region grown directly on Si are presented. At 100 K, a single-photon detection efficiency of 4% at 1310 nm wavelength was measured with a dark count rate of ~ 6 megacounts/s, resulting in the lowest reported noise-equivalent power for a Ge-on-Si single-photon avalanche diode detector (1×10-14 WHz-1/2). The first report of 1550 nm wavelength detection efficiency measurements with such a device is presented. A jitter of 300 ps was measured, and preliminary tests on after-pulsing showed only a small increase (a factor of 2) in the normalized dark count rate when the gating frequency was increased from 1 kHz to 1 MHz. These initial results suggest that optimized devices integrated on Si substrates could potentially provide performance comparable to or better than that of many commercially available discrete technologies

The Architecture of Communal Living: Lessons from Arcosanti in Arizona

Paolo Soleri's arcology model (architecture + ecology addresses issues of sustainability by advocating living in a balanced relationship between urban morphology and performance within dense, integrated and compact structures. Within these structures material recycling, waste reduction and the use of renewable energy sources are adopted as part of a sustainable strategy aimed at reducing the flow of resources and energy through the urban system. Today, as governments, eager to deliver major environmental improvements, press on with as yet untried and largely untested 'centrist' policies of urban living, there is a need to research relevant models of the 'compact city' approach. Issues involved with the intensification in the use of space, higher residential densities, centralisation, compactness, the integration of land uses and aspects of self-containment need to be examined. Over the last ten years, as the criteria of sustainability have become more widely accepted and understood, the relevance of the Soleri's urban model has become clearer. Arcosanti, begun in 1970, offers a laboratory for testing the validity of Soleri's ideas. This paper examines arcology and Arcosanti within the context of sustainability. Since the energy crisis of the mid 1970s, efforts at Arcosanti have been directed toward the definition and testing of various architectural effects on a community-wide scale that could offer a response to many of today's environmental problems. But progress is painstakingly slow. Lacking the level of funding and resources that would enable it to be convincing, Arcosanti now represents not so much a specific prototypal solution, but an activist-engaged strategy that advocates the possibility of building our dreams and visions. In a world plagued by so many problems and so few alternatives, it nevertheless continues to offer a beacon of hope on the threshold of a new millennium

Arcology and arcosanti: towards a sustainable built environment

Does theory arcology and practice (the Arcosanti Project) respond to the overlapping challenges in the movement toward more sustainable built environments