Sub-Kelvin resistance thermometer

A device capable of accurate temperature measurement down to 0.01 K of a particular object is discussed. The device is comprised of the following: a heat sink wafer; a first conducting pad bonded near one end of the heat sink wafer; a second conducting pad bonded near the other end of the heat sink wafer; and an oblong doped semiconductor crystal such as germanium. The oblong doped semiconductor crystal has a third conducting pad bonded on its bottom surface with the oblong doped semiconductor crystal bonded to the heat sink wafer by having the fourth conducting pad bonded to the first conducting pad. A wire is bonded between the second and third conducting pads. Current and voltage wires bonded to the first and second conducting pads measure the change in resistance of the oblong doped semiconductor crystal; this indicates the temperature of the object whose temperature is to be measured

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

Trends in Asylum Migration to Industrialized Countries: 1990-2001

asylum migration, industrialized countries, root causes, statistical trends

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

Decentralization and the post-war political economy

This paper uses cross-national data for 21 OECD nations to examine whether there is any evidence of a connection between measures of political and fiscal decentralization and the major, long-term, performance parameters of the post-war political economy. The findings of what is necessarily an exploratory analysis of a wide rage of policy outcomes suggest that low levels of fiscal centralization appear to have restrained post-war inflationary pressures and gone along with higher rates of post-war economic growth. However, no evidence is found to link fiscal decentralization with post-war labour market performance. While the balance of evidence indicates that measures of political decentralization do not have any significant impact on macroeconomic outcomes, the study confirms the standard finding in the literature that federalism and other decentralized constitutional arrangements impede the expansion of the socially protective state

The learning migration nexus: towards a conceptual understanding

Learning and identity formation are inescapable facets of the upheavals accompanying migration; movement across social space inevitably involves reflection, questioning and the need to learn new ways of being and new identities. Although migration is characterised by complexity and diversity, this paper suggests that we can identify key learning perspectives which illuminate the nexus between learning and migration. It argues for an approach which grounds learning in an understanding of socio-cultural space, and highlights the significance of policy discourses surrounding migration and integration. Within the conceptual framework suggested, the nature of learning is seen as multifaceted, and as having the potential to have both positive and negative outcomes for migrants

A sceptic looks at "housing theory"

A sceptic looks at "housing theory