SUMMARYPurpose: The purpose of this study was to identify sociodemographic disparities in health care use among epilepsy patients receiving care at different sites and the extent to which the disparities persisted after adjusting for patient characteristics and site of care. Methods: Three months of health care use data were obtained from baseline interviews of approximately 560 patients at four sites. One-half of the patients were from a Houston site and two NYC sites that serve predominantly low-income, minority, publicly insured, or uninsured patients. The other half were at the remaining site in Houston that serves a more balanced racial/ethnic and higher sociodemographic population. Differences in general and specialist visits, hospital emergency room (ER) care, and hospitalizations were associated with race/ethnicity, income, and coverage.Logistic regression was used to assess the extent to which the differences persisted when adjusting for individual patient characteristics and site of care. Results: Compared to whites, blacks and Hispanics had higher rates of generalist visits [odds ratio (OR) = 5.3 and 4.9, p < 0.05), ER care (OR = 3.1 and 2.9, p < 0.05) and hospitalizations (OR = 5.4 and 6.2, p < 0.05), and lower rates of specialist visits (OR = 0.3 and 0.4, p < 0.05). A similar pattern was found related to patient income and coverage. The magnitude and significance of the disparities persisted when adjusting for individual characteristics but decreased substantially or were eliminated when site of care was added to the model. Discussion: There are sociodemographic disparities in health care for people with epilepsy that are largely explained by differences in where patients receive care. KEY WORDS: Epilepsy, Health care utilization, Disparities, Sociodemographics, Race/ethnicity.A number of studies provide evidence that minorities with epilepsy in the United States receive different amounts of health care compared to nonminority whites (see literature reviews by Szaflarski et al., 2006 and Theodore et al., 2006). This is a concern for advocates and policy makers who seek to eliminate inequalities in epilepsy care and improve the health of high-risk populations. However, there are no studies examining the extent to which the disparities can be explained by such factors as differences in individual patient characteristics or variations in provider practices. We are conducting a 1-year longitudinal study of epilepsy care at four sites, two in Houston and two in Answers to such questions are needed to help inform program administrators, providers, and policy makers of the underlying reasons for disparities so that effective strategies might be designed to reduce or eliminate them.This report describes the methods used to conduct the study and provides preliminary results based on initial baseline data from the patient sample.

SUMMARYPurpose: To determine the persistence of disparities in health care use and outcomes in socioeconomically diverse populations of epilepsy patients. Methods: We followed patients for a year at one clinic in Houston and two in New York City that serve predominantly low-income, minority, Medicaid-insured, or uninsured patients, and a fourth clinic in Houston that serves a more balanced racial/ethnic and higher socioeconomic status (SES) population. We interviewed the patients several times regarding health care use, seizures, side effects, and outcomes, and examined differences between the patients at the three low-SES clinics and the patients at the high-SES clinic. Key Findings: After controlling for patients' age, gender, race/ethnicity, marital status, seizures, and side effects we found that low SES patients had consistently higher use of the hospital emergency room and more visits to a general practitioner. Hospitalizations were also consistently higher but the differences were not significant in most periods. Neurologist visits were relatively similar. Patients at the low SES sites also had a greater likelihood of having uncontrolled seizures, drug-related side effects, to be stigmatized, and have a lower overall quality of life throughout the study period. Significance: These findings suggest the persistence of SES-related disparities in health care use and outcomes among patients with epilepsy who are receiving regular care.

We propose the use of Ge1−xSnx heterojunction phototransistors (HPTs) as efficient optical receivers on Si substrates and analyze their performance. Our designs use n-Ge/pGe1−xSnx/n-Ge1−xSnx layers pseudomorphically grown on Si wafers via a Ge virtual substrate, which offers compatibility with complementary metal-oxide-semiconductor (CMOS) technology. By incorporating Sn into the Ge photon-absorbing layer to shrink the bandgap, the photodetection range can be significantly extended to the mid-infrared (MIR) region with a considerably enhanced optical response. The use of HPT structures provides optical conversion gain to further enhance the optical responsivity, thereby enabling efficient photodetection in the shortwave infrared region. We develop theoretical models to calculate the composition-dependent band alignments, the band structures (by taking into account the nonparabolic effect), the absorption coefficient, and the optical responsivity for the proposed GeSn HPTs. As the Sn content increases, the conduction band nonparabolicity becomes increasingly significant and considerably impacts the optical absorption coefficient. Moreover, analysis of the spectral response for the Ge1−xSnx HPTs shows that efficient photodetection covering the entirety of the fiber-optic telecommunication bands, as well as the emerging 2 µm MIR communication band, can be achieved. These results indicate that the proposed Ge1−xSnx HPTs are attractive for use as highresponsivity CMOS-compatible photodetectors in communication applications.

We have solved the continuity equation for electrons in the base of an InGaP-GaAs-GaAs heterojunction bipolar transistor laser (TL) in which the position of an InGaAs quantum well (QW) in GaAs base is variable. The injected minority carrier is related to the two-dimensional carrier in QW via virtual states (VSs). The values for optical gain in the QW are obtained by considering subband energies and envelope functions in presence of strain, polarization dependent momentum matrix element and Lorentzian lineshape. Relating the gain with threshold current and the latter with base current via VS current, the threshold base current and power output from the TL are estimated. Good agreement between the calculated and the experimental threshold base currents is obtained and the match for light output power is satisfactory within experimental uncertainty. Our calculated charge distribution in the base shows similar behaviour as in the charge control analysis of the experimental data.