267 research outputs found
White Beam Synchrotron X-Ray Topography of Gallium Arsenide
The defect structure of gallium arsenide is being examined using white beam transmission topography. The specimens under examination are cut-and-polished, three inch diameter, single crystal substrates from various suppliers in the âas receivedâ condition. The goal of this continuing program is to first document the existence of various crystallographic defect structures and then to establish their effect on the performance of microwave integrated circuits subsequently fabricated on the wafers. Success in establishing such a correlation might permit the use of an x-ray diffraction measurement to screen incoming material, eliminating marginal substrates and achieving a corresponding increase in yield
Avaliação da duração do desemprego nas regiÔes metropolitanas de Salvador e de São Paulo
Unusual effects of anisotropy on the specific heat of ceramic and single crystal MgB2
The two-gap structure in the superconducting state of MgB_2 gives rise to
unusual thermodynamic properties which depart markedly from the isotropic
single-band BCS model, both in their temperature- and field dependence. We
report and discuss measurements of the specific heat up to 16 T on ceramic, and
up to 14 T on single crystal samples, which demonstrate these effects in the
bulk. The behavior in zero field is described in terms of two characteristic
temperatures, a crossover temperature Tc_pi ~ 13 K, and a critical temperature
Tc = Tc_sigma ~ 38 K, whereas the mixed-state specific heat requires three
characteristic fields, an isotropic crossover field Hc2_pi ~ 0.35 T, and an
anisotropic upper critical field with extreme values Hc2_sigma_c ~ 3.5 T and
Hc2_sigma_ab ~ 19 T, where the indexes \pi and \sigma refer to the 3D and 2D
sheets of the Fermi surface. Irradiation-induced interband scattering tends to
move the gaps toward a common value, and increases the upper critical field up
to ~ 28 T when Tc = 30 K.Comment: 31 pages, 9 figures. Accepted in the Physica C special issue on MgB
The production and reproduction of inequality in the UK in times of austerity
Inequality appears to be back on the intellectual and political agenda. This paper provides a commentary on this renewed interest, drawing on an empirical discussion of inequality in the UK. The paper argues that inequality should be seen as produced in the inherently unequal social relations of production, drawing attention to the role of social struggle in shaping dynamics of inequality. However, inequality is not just produced in dynamic class struggle in the formal economy, but also through the social reproduction of labour power on a day-to-day and inter-generational basis. As such, inequalities of household resources at any point in time may be reproductive of greater future inequality. It is argued that inequality has risen in the UK over recent decades because of changes in the social relations of production in the formal economy and social reproduction in the domestic sector, both of which have witnessed significant state interventions that have increased structural inequalities. It is argued that, absent of significant change, the underpinning structural dynamics in the UK will lead to further increases in inequality over the short and longer-term. Given this, we might expect to see an already emergent âNew Politics of Inequalityâ intensifying in the coming decades.n/
Explaining the U-Shape of the Referral Hiring Pattern in a Search Model with Heterogeneous Workers
Using Unexpected Recalls to Examine the Long-Term Earnings Effects of Job Displacement
Does Money Buy Higher Schooling? Evidence from Secondary School Track Choice in Germany
- âŠ