Optical properties of digital-alloy InGaAlAs grown by molecular-beam epitaxy were parametrically investigated by 10-K-photoluminescence (PL) study on (In0.53Ga0.47As)n/(In0.52Al0.48As)n short-period superlattices (SPSs) in the range of n=1–5 monolayers. Two different peaks are resolved in PL spectra, and the higher energy peak (H) results from an excitonic transition while the lower energy peak (L) is related to a phonon-assisted transition. The H peak energies decrease monotonously as n increases, and it is in good agreement with the band-gap calculation with transfer matrix methods. It is found that two monolayer-period length (n=2) is the optimum one, where the PL intensity is largest and the ratio of L peak to H peak intensity is lowest. The various compositions (z) of digital-alloy In(Ga1−zAlz)As are prepared and their optical properties are investigated for z=0.2, 0.4, 0.6, and 0.8. The linewidths of 9-K-PL spectra for various z values are within the range of 10–15 meV, which are comparable to the best analog-alloy InGaAlAs.

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Background Low formal education level (EDUC), an indicator of socioeconomic status, is an established risk factor to develop rheumatoid arthritis (RA) as well as many other diseases,1 and low EDUC is associated with poor clinical status in RA according to patient questionnaires, joint counts and laboratory tests.2 Formal studies of possible associations of EDUC with more severe status in FM have not been reported. The diagnosis of FM depends primarily on a patient history of extensive pain and other symptoms, so clinical status might be best addressed by patient-reported outcomes (PROs) on self-report questionnaires. Objectives To investigate possible associations of EDUC, as well as age, duration of disease (DUR) and body mass index (BMI), with PRO scores in Korean patients with FM. Methods Responses of Korean patients with FM on the widespread pain index (WPI), symptom severity scale (SS), fibromyalgia impact questionnaire (FIQ), and multidimensional health assessment questionnaire/routine assessment of patient index data (MDHAQ/RAPID3) were analyzed. Statistical significance was tested using Spearman correlations of PROS with EDUC, age, DUR and BMI. A series of multivariate regressions was computed for each PRO as a dependent variable, and for age, DUR, BMI and EDUC as independent variables. Results In univariate correlations (data not shown) EDUC was correlated significantly with WPI (rho=-0.41, p=0.01), SS (rho=-0.47, p<0.01), FIQ-symptoms (rho=-0.39, p<0.02), FIQ-total score (rho=-0.35, p=0.03) and MDHAQ pain (rho=-0.33, p=0.04), generally at higher levels than age, DUR or BMI with these variables. Age also was correlated significantly with FIQ-overall impact, FIQ-symptoms, FIQ-total score, MDHAQ-PATGL and RAPID3; DUR also was correlated significantly with FIQ-overall impact, FIQ-symptoms and FIQ-total score (data not shown). No significant correlations were seen with BMI. In multivariate regressions (Table), EDUC was significantly and independently associated with SS, FIQ-symptoms, FIQ-total score, MDHAQ pain, RAPID3. Age also was significant in regressions, generally at lower beta coefficients than EDUC; DUR and BMI were not significant (Table 1). Table 1. Beta coefficient (p value) of regressions including 4 possible independent variables to explain variation in PRO domains in FM PRO domain Independent variables, Beta coefficient (p value) R 2 Age DUR BMI EDUC WPI −0.17 (0.12) 0.21 (0.15) 0.28 (0.46) −0.55 (0.05) 0.29 SS −0.11 (0.04) 0.01 (0.96) 0.13 (0.49) −0.27 (<0.05) 0.25 FIQ-function −0.02 (0.11) 0.03 (0.77) 0.05 (0.84) −0.05 (0.75) 0.08 FIQ-overall impact −0.24 (<0.01) 0.14 (0.21) 0.21 (0.47) −0.17 (0.43) 0.29 FIQ-symptoms −1.07 (<0.01) 0.81 (0.11) 0.70 (0.59) −2.26 (0.02) 0.40 FIQ-total score −1.42 (<0.01) 0.97 (0.13) 0.96 (0.57) −2.48 (<0.05) 0.37 MDHAQ-function −0.04 (0.137) −0.01 (0.76) 0.11 (0.21) −0.07 (0.24) 0.17 MDHAQ-pain −0.14 (0.01) −0.01 (0.95) −0.23 (0.25) −0.38 (0.01) 0.29 MDHAQ-patient global −0.14 (0.02) −0.02 (0.77) 0.16 (0.41) −0.20 (0...