Language, Employment and Earnings in the United States: Spanish-English Differentials from 1970 to 1990

This paper analyzes employment and earnings differentials between Spanish speakers and English speakers in the United States, using data from the 1970, 1980, and 1990 U.S. censuses. The results show that Spanish speakers, both men and women, do not perform as well in the labor market as English speakers. The results also reveal that Spanish-English earnings and unemployment differentials increased slightly in the 1970s, most likely because of rapid growth in the number of Spanish speakers. By contrast, these differentials increased sharply in the 1980s, also a period of rapidly increasing supply. However, there is no evidence that the widening of differentials in the 1980s reflects an increase in the labor market rewards to English language proficiency. Rather, they appear to be the result of Spanish speakers having relatively little of those labor market characteristics, most notably education, whose market value increased dramatically during the 1980s.

Models of Firm Behavior Under Minimum Wage Legislation

This paper sets out three simple models of firm behavior under minimum wage legislation. The key feature of these models is that they account for important aspects of the government's mechanism for monitoring and enforcing compliance with the minimum wage law. The major results of the paper are (1) that minimum wage legislation does not generally lead to upward movements along labor demand curves but rather, that it often leads to movements off, and to the left, of the labor demand curve; (2) that minimum wage legislation is likely to have a positive effect on the distribution of wages paid to workers who would earn less than the minimum in the absence of the legislation, but is not likely to bring all of those workers up to the minimum; and (3) that imposing additional penalties on second offenders promotes compliance by firms with no previous violations. The paper considers the implications of these results for empirical work on the adverse employment effects of minimum wage legislation andfor the design of government compliance mechanisms.

Double-walled carbon nanotube-based polymer composites for electromagnetic protection.

In this paper, we present a microwave absorber based on carbon nanotubes (CNT) dispersed inside a BenzoCycloButenw (BCB) polymer. The high aspect ratio and remarkable conductive characteristics of CNT give rise to good absorbing properties for electromagnetic protecting in microelectronic devices with very low concentration. In this article, nanocomposites are prepared using a solution-mixing method and are then evaluated and modeled by means of coplanar test structures. First, CNT concentrations are quantified by image processing. The nanocomposites implemented with coplanar test waveguides are then characterized using a vector network analyzer from 40 MHz to 20 GHz. An algorithm is developed to calculate the propagation constant "γ" constant "α", and relative effective complex permittivity (εreff = εreff' - jεreff'') for each CNT concentration. The extracted effective parameters are verified using the electromagnetic FEM-based Ansoft’s® high frequency structure simulator (HFSS). Power absorption (PA) of 7 dB at 15 GHz is obtained with only 0.37 weight percent of CNT concentration in the polymer matrix. The resulting engineerable and controllable composite provides consequently a novel degree of freedom to design and optimize innovative microwave components

The Changing Labor Market Position of Canadian Immigrants

This paper uses pooled 1971, 1981, and 1986 Canadian census data to evaluate the extent to which (1) the earnings of Canadian immigrants at the time of immigration fall short of the earnings of comparable Canadian-born individuals, and (2) immigrants' earnings grow more rapidly over time than those of the Canadian-born. Variations in the labor market assimilation of immigrants according to their gender and country of origin are also analyzed. The results suggest that recent immigrant cohorts have had more difficulty being assimilated into the Canadian labor market than earlier ones, an apparent consequence of recent changes in Canadian immigration policy, labor market discrimination against visible minorities, and the prolonged recession of the early 1980s.

Language, Employment, and Earnings in the United States: Spanish-English Differentials from 1970 to 1990

This paper analyzes employment and earnings differentials between Spanish speakers and English speakers in the United States, using data from the 1970, 1980, and 1990 U.S censuses. The results show that Spanish speakers, both men and women, do not perform as well in the labor market as English speakers. The results also reveal that Spanish-English earnings and unemployment differentials increased slightly in the 1970s, most likely because of rapid growth in the number of Spanish speakers. By contrast, these differentials increased sharply in the 1980s, also a period of rapidly increasing supply. However, there is no evidence that the widening of differentials in the 1980s reflects an increase in the labor market rewards to English language proficiency. Rather, they appear to be the result of Spanish speakers having relatively little of those labor market characteristics, most notably education, whose market value increased dramatically during the 1980s

Millimeter wave carbon nanotube gas sensor

This Letter reports experimental observations regarding the significant changes in the transmission modulus and phase of the propagating microwave signals up to 110 GHz in a micromachined coplanar waveguide supported on a dielectric membrane with a thickness of 1.4 m filled with a mixture of carbon nanotubes when exposed to nitrogen gas. These large shifts of amplitude and phase of microwave signals due to gas absorption represent the experimental basis on which a miniature wireless gas sensor could be implemented

Experimental determination of microwave attenuation and electrical permittivity of double-walled carbon nanotubes

The attenuation and the electrical permittivity of the double-walled carbon nanotubes (DWCNTs) were determined in the frequency range of 1–65 GHz. A micromachined coplanar waveguide transmission line supported on a Si membrane with a thickness of 1.4 µm was filled with a mixture of DWCNTs. The propagation constants were then determined from the S parameter measurements. The DWCNTs mixture behaves like a dielectric in the range of 1–65 GHz with moderate losses and an abrupt change of the effective permittivity that is very useful for gas sensor detection. ©2006 American Institute of Physic

The Changing Labor Market Position of Canadian Immigrants

This paper uses pooled 1971, 1981, and 1986 Canadian census data to evaluate the extent to which (1) the earnings of Canadian immigrants at the time of immigration fall short of the earnings of comparable Canadian-Born Individuals, and (2) immigrants' earnings grow more rapidly over time than those of the Canadian-born. Variations in the labor market assimilation of immigrants according to their gender and country of origin are also analyzed. The results suggest that recent immigrant cohorts have had more difficulty being assimilated into the Canadian labor market than earlier ones, an apparent consequence of recent changes in Canadian immigration policy, labor market discrimination against visible minorities, and the prolonged recession of the early 1980s

Dissociation between morphine-induced spinal gliosis and analgesic tolerance by ultra-low-dose α2-adrenergic and cannabinoid CB1-receptor antagonists.

Long-term use of opioid analgesics is limited by tolerance development and undesirable adverse effects. Paradoxically, spinal administration of ultra-low-dose (ULD) G-protein-coupled receptor antagonists attenuates analgesic tolerance. Here, we determined whether systemic ULD α2-adrenergic receptor (AR) antagonists attenuate the development of morphine tolerance, whether these effects extend to the cannabinoid (CB1) receptor system, and if behavioral effects are reflected in changes in opioid-induced spinal gliosis. Male rats were treated daily with morphine (5 mg/kg) alone or in combination with ULD α2-AR (atipamezole or efaroxan; 17 ng/kg) or CB1 (rimonabant; 5 ng/kg) antagonists; control groups received ULD injections only. Thermal tail flick latencies were assessed across 7 days, before and 30 min after the injection. On day 8, spinal cords were isolated, and changes in spinal gliosis were assessed through fluorescent immunohistochemistry. Both ULD α2-AR antagonists attenuated morphine tolerance, whereas the ULD CB1 antagonist did not. In contrast, both ULD atipamezole and ULD rimonabant attenuated morphine-induced microglial reactivity and astrogliosis in deep and superficial spinal dorsal horn. So, although paradoxical effects of ULD antagonists are common to several G-protein-coupled receptor systems, these may not involve similar mechanisms. Spinal glia alone may not be the main mechanism through which tolerance is modulated