Effects Of Demographic Covariates Research Articles

Integrating high-speed videos in capture-mark-recapture studies of insects.

Capture–mark–recapture (CMR) studies have been used extensively in ecology and evolution. While it is feasible to apply CMR in some animals, it is considerably more challenging in small fast‐moving species such as insects. In these groups, low recapture rates can bias estimates of demographic parameters, thereby handicapping effective analysis and management of wild populations. Here, we use high‐speed videos (HSV) to capture two large dragonfly species, Anax junius and Rhionaeschna multicolor, that rarely land and, thus, are particularly challenging for CMR studies. We test whether HSV, compared to conventional “eye” observations, increases the “resighting” rates and, consequently, improves estimates of both survival rates and the effects of demographic covariates on survival. We show that the use of HSV increases the number of resights by 64% in A. junius and 48% in R. multicolor. HSV improved our estimates of resighting and survival probability which were either under‐ or overestimated with the conventional observations. Including HSV improved credible intervals for resighting rate and survival probability by 190% and 130% in A. junius and R. multicolor, respectively. Hence, it has the potential to open the door to a wide range of research possibilities on species that are traditionally difficult to monitor with distance sampling, including within insects and birds.

Should students have a gap year? Motivation and performance factors relevant to time out after completing school.

Increasingly, school leavers are taking time out from study or formal work after completing high school?often referred to as a (involving structured activities such as volunteer tourism and unstructured activities such as leisure). Although much opinion exists about the merits-or otherwise-of taking time out after completing school, relatively little research has sought to understand the gap year from a psychoeducational perspective. Harnessing the theories of planned behavior and reasoned action and using structural equation modeling, the author examines the academic factors that predict gap year intentions among 2,502 high school students (Study 1) and the academic profile in respect to gap year participation of 338 students in university or college (Study 2). Findings in Study 1 show that postschool uncertainty and lower levels of academic motivation predict gap year intentions, that lower motivation and lower performance predict postschool uncertainty, and that these effects are significant over and above the effects of demographic (gender, age, ethnicity) covariates. Findings in Study 2 show that gap year participation positively predicts academic motivation and that this effect is significant over and above the effects of demographic covariates. The present investigation centrally positions psychoeducational theorizing in relation to the potential yields of a gap year in resolving problematic motivation and performance profiles that may have precipitated students' postschool uncertainty and interest in taking a year out after completing school.

Subregional femorotibial cartilage morphology in women – comparison between healthy controls and participants with different grades of radiographic knee osteoarthritis

To identify subregional differences in femorotibial cartilage morphology between healthy controls and women with different grades of radiographic knee osteoarthritis (OA). 158 women aged > or =40 years were studied. Weight-bearing extended anterior-posterior (AP) and Lyon schuss radiographs were obtained and the Kellgren Lawrence grade (KLG) determined. 97 women had a body mass index (BMI)< or =28, no symptoms, and were AP KLG0. 61 women had a BMI> or =30, symptoms in the target knee, and mild (KLG2=31) to moderate (KLG3=30) medial femorotibial radiographic OA in the AP views. Coronal spoiled gradient echo water excitation sequences were acquired at 3.0 Tesla. Total plate and regional measures of cartilage morphology of the weight-bearing femorotibial joint were quantified. KLG2 participants displayed, on average, thicker cartilage than healthy controls in the medial femorotibial compartment (particularly anterior subregion of the medial tibia (MT) and peripheral [external, internal] subregions of the medial femur), and in the lateral femur. KLG3 participants displayed significantly thinner cartilage than KLG0 participants in the medial weight-bearing femur (central subregion), in the external subregion of the MT, and in the internal subregion of the lateral tibia. These differences were generally unaffected when possible effects of demographic covariates were considered. The results indicate that in femorotibial OA regional cartilage thickening and thinning may occur, dependent on the (radiographic) disease status of the joint. These changes appear to display a heterogeneous spatial pattern, where certain subregions are more strongly affected than others.