Students' self-efficacy for science in different school systems

The important role of self-efficacy (SE) in students' motivation, engagement, persistence, and academic achievements has been reconfirmed by ample research, both in general and for STEM disciplines. As most studies focused on traditional school systems, additional research is needed on how science SE develops in different educational environments, which was the goal of this study. Data were collected from 1979 students in Grades 5–9 from 19 traditional, Waldorf, and democratic schools in Israel. Students completed a questionnaire that assessed their science self-efficacy (SSE), general and academic self-efficacy (GASE), and the sources of their SSE: teachers', parents', and peers' social persuasions, vicarious experiences and mastery experiences. Results revealed that SSE and GASE differed in their levels and in the way they changed with grade. These differences, and variations in the roles of the various sources of SSE, appeared to be influenced by the schools' cultures and curricula. Quantitative results are accompanied by verbal illustrative examples from interviews with students and teachers.     

Tilted post arrays for separating long DNA

Recent simulations by Chen and Dorfman [Electrophoresis 35, 405–411 (2014)] suggested that “tilting” the electric field with respect to the lattice vectors of a hexagonal post array would lead to a substantial improvement in electrophoretic DNA separations therein. We constructed such an array where the electric field is applied at an angle equidistant between the two lattice vectors. This tilted array leads to (i) baseline resolution of 20 kbp DNA and λ DNA (48.5 kbp) in a 4 mm channel and (ii) measurable separation resolutions for electric fields up to 50 V/cm, both of which are improvements over untilted post arrays of the same post density. The predicted time required to reach a resolution of unity is approximately 5 min, independent of electric field. The separations are more reproducible at higher fields.     

Onset of channeling during DNA electrophoresis in a sparse ordered post array

The “channeling hypothesis” of DNA electrophoresis in sparse, ordered arrays of posts predicts that the DNA will move through the array relatively unhindered if (i) the spacing between the posts is larger than the DNA coil and (ii) the electric field lines are straight. We tested this hypothesis by studying the electrophoretic separation of a small plasmid DNA (pUC19, 2686 base pairs) and a large, linear DNA (λ-DNA, 48 500 base pairs) in a hexagonal array of 1 μm diameter posts with a pitch of 7 μm. At low electric field strengths, these DNAs are separated due to the long-lived, rope-over-pulley collisions of λ-DNA with the posts. The resolution is lost as the electric field increases due to the onset of channeling by the λ-DNA. Using a diffusive model, we show that channeling arises at low electric fields due to the finite size of the array. This channeling is not intrinsic to the system and is attenuated by increasing the size of the array. Higher electric fields lead to intrinsic channeling, which is attributed to the disparate time scales for a rope-over-pulley collision and transverse diffusion between collisions. The onset of channeling is a gradual process, in agreement with extant Brownian dynamics simulation data. Even at weak electric fields, the electrophoretic mobility of λ-DNA in the array is considerably higher than would be expected if the DNA frequently collided with the posts.     

Emeritus professors: Correlates of professional activity in retirement II

Dorfman (1980b) investigated correlates of professional activity in retirement of professors at a major state university who continued to reside in their academic community during the entire year. This follow-up study extends that research to the total population of emeriti by including emeriti who left the University community after retirement and emeriti who continued to live in the University community for part of the year. Interviews were conducted with 113 University of Iowa emeritus professors. There was consistency between level of professional activity during the preretirement career and level of professional activity in retirement for the entire group, with stayers more consistent than leavers. Significant correlates of professional activity in retirement for the entire group included rated importance of consulting and University service, strength of ties to colleagues and professional organizations outside the University, contacts with former students, and perceived rapidity of changes in knowledge in respondents' fields. Multiple regression results showed that the strongest predictors of professional activity in retirement were level of professional activity during the preretirement career and strength of ties to professional organizations outside the University.     

A faculty views its retirement benefit plan: An empirical observation and analysis

What is the level of a faculty's knowledge of its pension plan, and what are its attitudes toward and opinions of its benefit plan? A questionnaire solicited data from one faculty in order to investigate these questions, as well as to measure the effect of marital status, the number of years employed, and proximity to retirement on the responses.     

Evaluation of the Kirkwood approximation for the diffusivity of channel-confined DNA chains in the de Gennes regime

We use Brownian dynamics with hydrodynamic interactions to calculate both the Kirkwood (short-time) diffusivity and the long-time diffusivity of DNA chains from free solution down to channel confinement in the de Gennes regime. The Kirkwood diffusivity in confinement is always higher than the diffusivity obtained from the mean-squared displacement of the center-of-mass, as is the case in free solution. Moreover, the divergence of the local diffusion tensor, which is non-zero in confinement, makes a negligible contribution to the latter diffusivity in confinement. The maximum error in the Kirkwood approximation in our simulations is about 2% for experimentally relevant simulation times. The error decreases with increasing confinement, consistent with arguments from blob theory and the molecular-weight dependence of the error in free solution. In light of the typical experimental errors in measuring the properties of channel-confined DNA, our results suggest that the Kirkwood approximation is sufficiently accurate to model experimental data.     

Measurements of DNA barcode label separations in nanochannels from time-series data

We analyzed time-series data for fluctuations of intramolecular segments of barcoded E. coli genomic DNA molecules confined in nanochannels with sizes near the persistence length of DNA. These dynamic data allowed us to measure the probability distribution governing the distance between labels on the DNA backbone, which is a key input into the alignment methods used for genome mapping in nanochannels. Importantly, this dynamic method does not require alignment of the barcode to the reference genome, thereby removing a source of potential systematic error in a previous study of this type. The results thus obtained support previous evidence for a left-skewed probability density for the distance between labels, albeit at a lower magnitude of skewness. We further show that the majority of large fluctuations between labels are short-lived events, which sheds further light upon the success of the linearized DNA genome mapping technique. This time-resolved data analysis will improve existing genome map alignment algorithms, and the overall idea of using dynamic data could potentially improve the accuracy of genome mapping, especially for complex heterogeneous samples such as cancer cells.     

Reactions of professors to retirement: A comparison of retired faculty from three types of institutions

Dorfman et al. (1982) compared the professional activities of retired professors from liberal arts colleges, a comprehensive university, and a major research university. This companion piece based on the same survey compares the professors' reactions to retirement. Results show that a majority of faculty from all types of institutions plan for retirement, are positive about retirement, and give suggestions for institutional retirement policy. The retired professors recommend the following: (1) help in planning, (2) more information about retirement, (3) support for continued work, (4) gradual retirement. Major differences among institutions are the following: (1) comprehensive university faculty plan for retirement more than do faculty from the other institutions, (2) faculty from both universities begin financial planning at a younger age than do faculty from the liberal arts colleges, (3) research university faculty miss work and like having time to spend on professional activities more than do faculty from the other institutions.     

Ten Years Later: A Follow-Up Study of Professors Still Working After Age 70

Little is known about the impact of the end of mandatory retirement on professors over the long term. This follow-up study investigated the ten-year experience of professors who chose not to retire from a major research university after the elimination of the age 70 mandatory retirement in 1994. The initial interview study was conducted in 1998 (Dorfman, 2000 Dorfman , L. T. ( 2000 ). Still working after age 70: Older professors in academe . Educational Gerontology , 26 , 695 – 713 .[Taylor & Francis Online], [Web of Science ®] , [Google Scholar], 2002 Dorfman , L. T. ( 2002 ). Stayers and leavers: Professors in an era of no mandatory retirement . Educational Gerontology , 28 , 15 – 33 .[Taylor & Francis Online], [Web of Science ®] , [Google Scholar]). All surviving professors (n = 13; age 80–84) agreed to be reinterviewed in 2007. The study investigated major reasons for continuing to work or retire, professional and nonprofessional activities, perceptions of departmental and institutional atmosphere and student and faculty attitudes toward older faculty, and preparation and plans for retirement. Content analysis of the tape-recorded open-ended questions revealed that employed professors continued to work mainly because they enjoyed it. Retired professors retired mainly because of age or felt it was time to retire. Retired professors as well as their employed counterparts continued professional activities, primarily research. Both groups reported mixed reactions to the overall atmosphere in their departments and university as well as to student and faculty attitudes toward older faculty, with one-third of retirees reporting departmental or institutional pressures to retire. The major type of planning for retirement was financial.