Design of an adiabatic demagnetization refrigerator for studies in astrophysics

An adiabatic demagnetization refrigerator was designed for cooling infrared bolometers for studies in astrophysics and aeronomy. The design was tailored to the requirements of a Shuttle sortie experiment. The refrigerator should be capable of maintaining three bolometers at 0.1 K with a 90% cycle. The advantage are of operations the bolometer at 0.1K. greater sensitivity, faster response time, and the ability to use larger bolometer elements without compromising the response time. The design presented is the first complete design of an ADR intended for use in space. The most important of these specifications are to survive a Shuttle launch, to operate with 1.5 K - 2.0 K space-pumped liquid helium as a heat sink, to have a 90% duty cycle, and to be highly efficient

Design concepts for the ASTROMAG cryogenic system

Described is a proposed cryogenic system used to cool the superconducting magnet for the Space Station based ASTROMAG Particle Astrophysics Facility. This 2-meter diameter superconducting magnet will be cooled using stored helium II. The paper presents a liquid helium storage concept which would permit cryogenic lifetimes of up to 3 years between refills. It is proposed that the superconducting coil be cooled using superfluid helium pumped by the thermomechanical effect. It is also proposed that the storage tank be resupplied with helium in orbit. A method for charging and discharging the magnet with minimum helium loss using split gas-cooled leads is discussed. A proposal to use a Stirling cycle cryocooler to extend the storage life of the cryostat will also be presented

Report of the sensor cooler technology panel

The Sensor Cooler Technology Panel identified three major areas in which technology development must be supported in order to meet the system performance requirements for the Astrotech 21 mission set science objectives. They are: long life vibration free refrigerators; mechanical refrigeration for 2 K to 5 K; and flight testing of emerging prototype refrigerators. A development strategy and schedule were recommended for each of the three areas

Portuguese emigration today

Portuguese emigration increased ever since its interruption by the 1974 revolution, especially since Portugal became a member of the then European Economic Community. This increase was underpinned by the regime of free movement of people within the European Union, which has helped transform Europe into the lead destination of Portuguese emigration. The effects of the 2008 financial crisis on this migratory dynamic have proven complex. In the first instance, the fact that this crisis was global prompted a downturn in emigration. However, in a second phase, there was new and very marked growth in the rate of Portuguese emigration coupled with changes to the hierarchy of destinations. The greatest of these alterations was the abrupt decline in the numbers departing for Spain, which was overtaken by the United Kingdom as the main destination for emigration. From a comparative perspective, the joint effects of the growth in emigration and the stagnation of immigration mean that Portugal is today among the least attractive countries in EU. As a consequence, international migratory patterns in Portugal today – as in the 1960s – are exacerbating rather than countering the population decline in the country with the lowest fertility rate in Europe.info:eu-repo/semantics/publishedVersio

Transnationalism and Social Work Education

Transnational movements, networks, and relationships are everywhere in this “world on the move” (Williams & Graham, 2014, p. i1). Transnational peoples maintain relationships of interdependence and support with families and communities in their places of origin, often returning regularly, while starting new lives and making new connections. Transnationalism is characterized by mobilities and networks, by social integration, and by extended and extensive relationship ties of family, neighborhood, religious faith, or combinations thereof (Valtonen, 2008). While disciplines across the world including sociology, human geography, and cultural anthropology engage with the implications of transnationalism (Bauböck & Faist, 2010), social work in England and mainland Europe has not achieved similar levels of engagement. As Cox and Geisen state: “the social world is being transformed by migration and social work is playing catch-up” (2014, p. i162)