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.

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.

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.

Role of the medial part of the intraparietal sulcus in implementing movement direction

The contribution of the posterior parietal cortex (PPC) to visually guided movements has been originally inferred from observations made in patients suffering from optic ataxia. Subsequent electrophysiological studies in monkeys and functional imaging data in humans have corroborated the key role played by the PPC in sensorimotor transformations underlying goal-directed movements, although the exact contribution of this structure remains debated. Here, we used transcranial magnetic stimulation (TMS) to interfere transiently with the function of the left or right medial part of the intraparietal sulcus (mIPS) in healthy volunteers performing visually guided movements with the right hand. We found that a "virtual lesion" of either mIPS increased the scattering in initial movement direction (DIR), leading to longer trajectory and prolonged movement time, but only when TMS was delivered 100-160 ms before movement onset and for movements directed toward contralateral targets. Control experiments showed that deficits in DIR consequent to mIPS virtual lesions resulted from an inappropriate implementation of the motor command underlying the forthcoming movement and not from an inaccurate computation of the target localization. The present study indicates that mIPS plays a causal role in implementing specifically the direction vector of visually guided movements toward objects situated in the contralateral hemifield

The Thermal Evolution of the Donors in AM CVn Binaries

(Abridged) We calculate the full stellar-structural evolution of donors in AM CVn systems formed through the WD channel coupled to the binary's evolution. Contrary to assumptions made in prior modelling, these donors are not fully convective over much of the AM CVn phase and do not evolve adiabatically under mass loss indefinitely. Instead, we identify three distinct phases of evolution: a mass transfer turn-on phase (during which the orbital period continues to decrease even after contact, the donor contracts, and the mass transfer rate accelerates to its maximum), a phase in which the donor expands adiabatically in response to mass loss, and a cooling phase beginning at orbital periods of approximately 45--55 minutes during which the donor contracts. The physics that determines the behaviour in the first and third phases, both of which are new outcomes of this study, are discussed in some detail. We find the overall duration of the turn-on phase to be between $\sim 10^4$-$10^6$ yrs, significantly longer than prior estimates. We predict the donor's luminosity and effective temperature. During the adiabatic expansion phase (ignoring irradiation effects), the luminosity is approximately $10^{-6}$--$10^{-4} L_\odot$ and the effective temperature is approximately 1000--1800 K. However, the flux generated in the accretion flow dominates the donor's intrinsic light at all times. The impact of irradiation on the donor extends the phase of adiabatic expansion to longer orbital periods and alters the donor's observational characteristics. Irradiated donors during the adiabatic phase can attain a surface luminosity of up to $\approx10^{-2} L_\odot$. We argue that the turn-on and cooling phases both will leave significant imprints on the AM CVn population's orbital period distribution.Comment: (20 pages, 20 figures, accepted to the Monthly Notices of the Royal Astronomical Society

Phonon-phonon interactions in transition metals

In this paper the phonon self energy produced by anharmonicity is calculated using second order many body perturbation theory for all bcc, fcc and hcp transition metals. The symmetry properties of the phonon interactions are used to obtain an expression for the self energy as a sum over irreducible triplets, very similar to integration in the irreducible part of the Brillouin zone for one particle properties. The results obtained for transition metals shows that the lifetime is on the order of 10^10 s. Moreover the Peierls approximation for the imaginary part of the self energy is shown to be reasonable for bcc and fcc metals. For hcp metals we show that the Raman active mode decays into a pair of acoustic phonons, their wave vector being located on a surface defined by conservation laws.Comment: 14 pages, 3 figure

A follow-up study of 100 reading disability cases, now adults, who were associated with the Boston University Education Clinic between 1936-1948

Thesis (Ed.M.)--Boston Universit