Monitoring the dielectric response of single cells following mitochondrial adenosine triphosphate synthase inhibition by oligomycin using a dielectrophoretic cytometer

One of the main uses of adenosine triphosphate (ATP) within mammalian cells is powering the Na⁺/K⁺ ATPase pumps used to maintain ion concentrations within the cell. Since ion concentrations determine the cytoplasm conductivity, ATP concentration is expected to play a key role in controlling the cytoplasm conductivity. The two major ATP production pathways within cells are via glycolysis within the cytoplasm and via the electron transport chain within the mitochondria. In this work, a differential detector combined with dielectrophoretic (DEP) translation in a microfluidic channel was employed to observe single cell changes in the cytoplasm conductivity. The DEP response was made sensitive to changes in cytoplasm conductivity by measuring DEP response versus media conductivity and using double shell models to choose appropriate frequencies and media conductivity. Dielectric response of Chinese hamster ovary (CHO) cells was monitored following inhibition of the mitochondria ATP production by treatment with oligomycin. We show that in CHO cells following exposure to oligomycin (8 μg/ml) the cytoplasm conductivity drops, with the majority of the change occurring within 50 min. This work demonstrates that dielectric effects due to changes in ATP production can be observed at the single cell level.     

Teachers' goal orientations for teaching: Associations with instructional practices,interest in teaching,and burnout

Two studies (one longitudinal) were designed to extend Butler's model of teachers' goal orientations for teaching. In Study 1, results from 281 teachers in Germany confirmed the predicted four-factor model comprising mastery, ability-approach, ability-avoidance, and work-avoidance goal orientations. As expected, mastery orientation and work avoidance emerged as positive and negative predictors, respectively, of adaptive patterns of instruction (mastery-oriented practices and cognitive stimulation) and high interest in teaching and low burnout; associations for both ability orientations were less consistent. In Study 2, 69 Israeli teachers completed the measures of instructional practices, interest in teaching and burnout several months after reporting their goal orientations. Results were very similar to those of Study 1. The two studies confirm that research on teachers' goal orientation is promising and has implications for understanding how teacher motivation might influence both teachers and their students.     

Diverse Colleges of Origin of African American Doctoral Recipients, 2001–2005: Historically Black Colleges and Universities and Beyond

The contribution of HBCUs as “colleges of origin,” i.e., where Black doctorates earned their bachelors’ degrees, remains of interest, given the historical role of HBCUs and the current desire to increase the percentage of doctorates awarded to African Americans in all fields. Using national survey data from multiple sources, we estimated which college characteristics predicted later doctoral degree attainment in all fields. We took into account the large number of Black graduates from HBCUs, which make them likely to be colleges of origin, and controlled for standardized test scores, Carnegie classification, and student/faculty ratio. HBCUs were associated with doctorate production more than twice the expected level based on their other average characteristics. In addition, colleges with low student/faculty ratios, higher SAT scores, and historical Carnegie classifications of research universities and selective liberal arts colleges were also associated with a higher percentage of Black graduates later earning doctoral degrees.     

Sex Differences in Goals for Supportive Interactions

One explanation for sex differences in supportive behavior is that men and women pursue different goals in supportive interactions. Sex differences in goals may themselves be explained by personality traits such as expressivity and supportive self‐efficacy, or situational factors such as target responsibility. The current study examined sex differences in the pursuit of eight supportive goals, and the extent to which differences were explained by personality and situational factors. Participants (254 men, 386 women) read hypothetical scenarios involving a distressed friend who was depicted as responsible or not responsible for his or her problematic situation, and responded to measures of supportive goals and personality traits. Results indicate that women are somewhat more likely to pursue a range of goals that are likely to result in effective supportive messages (e.g., emotional support, problem‐solving). Many of the sex differences in goal pursuit were mediated by the personality traits of expressivity and supportive self‐efficacy.