Improved Hole Transport by p-InxGa1-xN Layer in Multiple Quantum Wells of Visible LEDs

Studied is the effect of indium (In) mole fraction in p-InxGa(1-x)N: Mg layers with 0 <= x(In) <= 0.035 on hole injection and transport behaviors in InGaN/GaN multiple quantum wells (MQWs) using dual-wavelength and triple-wavelength active regions. Electro-optical characteristics of light-emitting diodes containing p-layers with different In content and with silicon doping in selected QW barriers (QWBs) are compared to evaluate hole transport in the active region. The results show that enhanced hole transport and corresponding more uniform distribution of holes across the MQW region are achieved by increasing x(In) in the p-InxGa1-xN:Mg layer, possibly due to modification in energy of holes by a potential barrier between the p-InGaN and GaN QWB

Comparative Value of Four Measures of Retention in Expert Care in Predicting Clinical Outcomes and Health Care Utilization in HIV Patients

This study compared the ability of four measures of patient retention in HIV expert care to predict clinical outcomes. This retrospective study examined Veterans Health Administration (VHA) beneficiaries with HIV (ICD-9-CM codes 042 or V08) receiving expert care (defined as HIV-1 RNA viral load and CD4 cell count tests occurring within one week of each other) at VHA facilities from October 1, 2006, to September 30, 2008. Patients were ≥18 years old and continuous VHA users for at least 24 months after entry into expert care. Retention measures included: Annual Appointments (≥2 appointments annually at least 60 days apart), Missed Appointments (missed ≥25% of appointments), Infrequent Appointments (>6 months without an appointment), and Missed or Infrequent Appointments (missed ≥25% of appointments or >6 months without an appointment). Multivariable nominal logistic regression models were used to determine associations between retention measures and outcomes. Overall, 8,845 patients met study criteria. At baseline, 64% of patients were virologically suppressed and 37% had a CD4 cell count >500 cells/mm3. At 24 months, 82% were virologically suppressed and 46% had a CD4 cell count >500 cells/mm3. During follow-up, 13% progressed to AIDS, 48% visited the emergency department (ED), 28% were hospitalized, and 0.3% died. All four retention measures were associated with virologic suppression and antiretroviral therapy initiation at 24 months follow-up. Annual Appointments correlated positively with CD4 cell count >500 cells/mm3. Missed Appointments was predictive of all primary and secondary outcomes, including CD4 cell count ≤500 cells/mm3, progression to AIDS, ED visit, and hospitalization. Missed Appointments was the only measure to predict all primary and secondary outcomes. This finding could be useful to health care providers and public health organizations as they seek ways to optimize the health of HIV patients