Using the SRQ–20 factor structure to examine changes in mental distress following typhoon exposure

Empirical research is limited regarding postdisaster assessment of distress in developing nations. This study aimed to evaluate the factor structure of the 20-item Self-Reporting Questionnaire (SRQ–20) before and after an acute trauma, Typhoon Xangsane, in order to examine changes in mental health symptoms in an epidemiologic sample of Vietnamese adults. The study examined a model estimating individual item factor loadings, thresholds, and a latent change factor for the SRQ–20’s single “general distress” common factor. The covariates of sex, age, and severity of typhoon exposure were used to evaluate the disaster-induced changes in SRQ–20 scores while accounting for possible differences in the relationship between individual measurement scale items and the latent mental health construct. Evidence for measurement noninvariance was found. However, allowing sex and age effects on the pre-typhoon and post-typhoon factors accounted for much of the noninvariance in the SRQ–20 measurement structure. A test of no latent change failed, indicating that the SRQ–20 detected significant individual differences in distress between pre- and post-typhoon assessment. Conditioning on age and sex, several typhoon exposure variables differentially predicted levels of distress change, including evacuation, personal injury, and peri-event fear. On average, females and older individuals reported higher levels of distress than males and younger individuals, respectively. The SRQ–20 is a valid and reasonably stable instrument that may be used in postdisaster contexts to assess emotional distress and individual changes in mental health symptoms

Deep-level transient spectroscopy and electrical characterization of ion-implanted p-n junctions into undoped InP

Current-voltage, small-signal measurements, and deep-level transient spectroscopy (DLTS) spectra of p-n junctions made by Mg implantation into undoped InP are described. The I-V characteristics show that the dominant conduction mechanism at forward bias is recombination in the space-charge zone, whereas a thermally activated tunneling mechanism involving a trap at 0.32 eV dominates at reverse bias. Five deep levels located in the upper-half of the band gap were detected in the junctions by DLTS measurements, three of which (at 0.6, 0.45, and 0.425 eV) were found to appear due to rapid thermal annealing. The origin of the other two levels, at 0.31 and 0.285 eV, can be ascribed to implantation damage. Admittance spectroscopy measurements showed the presence of three levels at 0.44, 0.415, and 0.30 eV, all in agreement with those found by DLTS. The DLTS measurements showed that the concentration of deep levels decreased after longer annealing times, and that the concentration of deep levels due to the implantation increased after additional P or Si implantations. This explains the influence of annealing time and additional implantations on the I-V characteristics of the junctions