Dynamic photoconductive gain effect in shallow-etched AlGaAs/GaAs quantum wires

We report on a dynamic photoconductive gain effect in quantum wires which are lithographically fabricated in an AlGaAs/GaAs quantum well via a shallow-etch technique. The effect allows resolving the one-dimensional subbands of the quantum wires as maxima in the photoresponse across the quantum wires. We interpret the results by optically induced holes in the valence band of the quantum well which shift the chemical potential of the quantum wire. The non-linear current-voltage characteristics of the quantum wires also allow detecting the photoresponse effect of excess charge carriers in the conduction band of the quantum well. The dynamics of the photoconductive gain are limited by the recombination time of both electrons and holes

THE EFFECTS OF ACTIVE LEARNING TECHNOLOGY ON INSTRUCTORS’ PRACTICES AND STUDENTS’ ENGAGEMENT AND GRADES: A MIXED METHODS STUDY

Partly in response to university teachers’ changing pedagogies marked by flipping instruction, lecture capture technologies are evolving into active learning systems. Little published research exists on the effects of active learning technology on either teachers or students. This two-phase sequential explanatory mixed methods study details the effects that active learning systems have on instructor practices and on student grades and engagement. Phase one combined quantitative data collection with instructor interviews. Phase one findings show higher student engagement levels correlate with the use of the active learning system only in the presence of very specific, flipped classroom practices. Phase two, a multiple case study, contextualizes those findings by detailing the students’ experiences. Focus groups held within each of three bounded cases yielded multiple themes, which, coupled with the phase one results, led to five key findings. Primary among these findings are: 1) Active learning technology only correlates to higher engagement or grades when the teacher advocates frequently for the system’s use and students use it often, and 2) students have positive perceptions of active learning technology, use it primarily to prepare for exams, and on occasion change their note taking or attendance behaviors. Three recommendations for future research and practice follow a discussion of these findings. Advisor: Allen Steckelber

Adaptive colour change and background choice behaviour in peppered moth caterpillars is mediated by extraocular photoreception

Light sensing by tissues distinct from the eye occurs in diverse animal groups, enabling circadian control and phototactic behaviour. Extraocular photoreceptors may also facilitate rapid colour change in cephalopods and lizards, but little is known about the sensory system that mediates slow colour change in arthropods. We previously reported that slow colour change in twig-mimicking caterpillars of the peppered moth (Biston betularia) is a response to achromatic and chromatic visual cues. Here we show that the perception of these cues, and the resulting phenotypic responses, does not require ocular vision. Caterpillars with completely obscured ocelli remained capable of enhancing their crypsis by changing colour and choosing to rest on colour-matching twigs. A suite of visual genes, expressed across the larval integument, likely plays a key role in the mechanism. To our knowledge, this is the first evidence that extraocular colour sensing can mediate pigment-based colour change and behaviour in an arthropod

Interview with Fred Hof by Brien Williams

Biographical NoteFrederic C. Hof was born on July 14, 1947, to Alice and Frederic Hof in Brooklyn, New York. Before he was school-age his family moved to Port Washington, New York, on Long Island. In the summer of 1964, after his junior year of high school, he participated in an exchange program and went to Damascus, Syria. He completed high school in Port Washington and then attended the Georgetown University School of Foreign Service. At Georgetown he participated in ROTC and was commissioned as a second lieutenant in the Army. He spent 1970 in Vietnam with the 101st Air Mobile Division (now the 101st Airborne), and returned to teach in the Civil Affairs School. He then entered the Foreign Area Officer Program to specialize in the Middle East, and as part of that program he attended the Defense Language Institute in Monterey, California, and the Foreign Service Institute in Tunis to learn Arabic. He served as the Army attaché in Beirut, Lebanon, and in 1982 he was wounded while crossing the Green Line and was awarded a Purple Heart. He worked in the office of the secretary of defense in the International Security Affairs office. He retired from the Army and took a position at the State Department. He and Richard Armitage opened Armitage Associates, LLC in 1993. In late 2000, he was asked to join the Sharm el-Sheikh Fact-Finding Committee and served on that committee from January 2001 until it completed its report the following May. SummaryInterview includes discussion of: Hof’s education; Hof’s exchange program experience in Damascus, Syria; relations between Americans and Syrians; Hof’s military career in Vietnam, teaching in the Civil Affairs School, the Foreign Area Officer Program, and Lebanon; the role of the Defense Language Institute; working in the office of the secretary of defense; getting wounded in Lebanon and receiving the Purple Heart; working on the commission to investigate the bombing of the barracks in Beirut; working for the State Department under Secretary Baker and Richard Armitage; the effects of transitioning from the first Bush administration to the Clinton administration, and to the second Bush administration in 2001; opening Armitage Associates, LLC; being asked by Laurence Pope to join the Sharm el-Sheikh Fact-Finding Committee; Pope’s reasons for leaving the project; the goals of the fact-finding committee; Hof’s role in the fact-finding committee, the relationship among the members and Mitchell’s role; working with the Israeli government and the change in that relationship when Sharon succeeded Barak; the approach that the working group took to meeting with principal people on both sides; setting up the committee’s visit; Hof’s contact with the Office of the Vice President; security in Gaza; the atmosphere of the visit; writing the Mitchell report; Mitchell’s ability to reconcile different views within the report and achieve a consensus within the group; a sense of a lost opportunity when there was little follow-through on the committee’s recommendations; Mitchell’s appointment to be special envoy to the Middle East; the prospects of a two-state solution and America’s role in it; and Mitchell’s political skill and optimism and how that can be brought to bear in international peacemaking

Wirkung des Gemengeanbaus mit Körnerleguminosen sowie der Standraumzuteilung und der Saatstärke auf Kornertrag und Kornproteingehalt von Winterweizen

In stockless organic farms it is difficult to produce winter wheat (Triticum aestivum L.) with high protein content. The objective of this study was to evaluate the effects of intercropping of (i) winter wheat with either winter field bean (Vicia faba L.) or winter pea (Pisum sativum L.), (ii) the spatial arrangement (mixed, row or row-strip intercrop) and (iii) the seeding rate of the wheat (100 or 20 %) on yield formation and grain protein content. Monocropped wheat planted at a seeding rate of 20 % significantly out-yielded monocropped wheat at 100 % seeding rate because of a more efficient use of the mineral nitrogen (N) in soil. A gradient in the spatial and temporal use of mineral soil N by the wheat was found. N was available in particular from deeper soil layers during the grain filling phase in row strip intercrop trials, resulting in a higher grain protein content of the wheat. Monocropped wheat achieved mean protein content levels of 9,9 and 9,4 % at two different sites and protein content increased significantly in mixture (mean: 12,8 and 11,4 %). The highest protein content of 15,4 % was achieved with the row strip intercrop of field bean

A clinical delineation of Tachyphemia (cluttering)

Cluttering constitutes one of the most important disorders of speech, language and communication in general. The majority of c1utterers are themselves unaware of the disorder. The problems of definition, symptomatology, aetiology and relationship to stuttering and hereditary aspects, are discussed. A preliminary case report of a family in which cluttering appears to follow a dominant mode of inheritance, is given. It is concluded that the major symptoms underlying the general cluttering syndrome in the family described, are related to some form of psychoneurological dysfunction with emphasis on a central language imbalance.S. Afr. Med. J., 48, 1624 (1974

Career changers in teaching jobs: A case study based on the Swiss vocational education system

This study investigates the determinants and motives of professionals who change career to vocational teaching. The framework for this study is the Swiss vocational education system, which requires that teachers of vocational subjects must have a prior career in that specific field. Thus, to work in teaching, every vocational teacher has to change his or her initial career. This paper focuses on the relevance of monetary motives for changing a career to teaching. Using a unique data set of trainee teachers, we show that professionals who change their careers to teaching earned on average more in their first career than comparable workers in the same occupation. Our findings additionally demonstrate that the average career changer still expects to earn significantly more as a teacher than in the former career. However, the study shows substantial heterogeneity and a zero wage elasticity of the teacher supply, suggesting that non-monetary motives are more relevant for career change than monetary factors

Salmonella typhimurium strains carrying hemolysin plasmids and cloned hemolysin. genes from Escherichia coli

Like all other Salmonella typhimurium strains examined, the smooth variants SF1397 (L T2) and 1366 and also their semi-rough and rough derivatives are non-haemolytic. Nevertheless, two haemolysin (Hly) plasmids of E. coli belonging to the inc groups incFllI,lv (pSU316) and incIz (pHly152) were able to be introduced into these strains by conjugation and stably maintained. A considerable percentage of the Hly+ transconjugants obtained had lost parts of their O-side chains, a result of selection for the better recipient capability of « semi-rough» variants rather than the direct influence of the Hly+ plasmids themselves. In contrast to the incF1lI1V plasmid pSU316, which exhibited higher conjugation rates with rough recipients, the incIz plasmid pHly152 was accepted best by smooth strains. Transformation with cloned E. coli haemolysin (hly) determinant was inefficient ( <10-8) for smooth strains, but 102-103 times higher for rough recipients, and was increased by the use of Salmonella-modified DNA. The transform ants and transconjugants were relatively stable and showed the same haemolytic activity as the E. coli donor strains. The virulence of the Hly+ smooth, semi-rough and rough S. typhimurium strains was tested in two mouse models, and neither the mortality rate nor the ability to multiply within the mouse spleen was influenced by the hly determinants

The TRPM4 channel inhibitor 9-phenanthrol

The phenanthrene-derivative 9-phenanthrol is a recently identified inhibitor of the transient receptor potential melastatin (TRPM) 4 channel, a Ca2+-activated non-selective cation channel whose mechanism of action remains to be determined. Subsequent studies performed on other ion channels confirm the specificity of the drug for TRPM4. In addition, 9-phenanthrol modulates a variety of physiological processes through TRPM4 current inhibition and thus exerts beneficial effects in several pathological conditions. 9-Phenanthrol modulates smooth muscle contraction in bladder and cerebral arteries, affects spontaneous activity in neurons and in the heart, and reduces lipopolysaccharide-induced cell death. Among promising potential applications, 9-phenanthrol exerts cardioprotective effects against ischaemia-reperfusion injuries and reduces ischaemic stroke injuries. In addition to reviewing the biophysical effects of 9-phenanthrol, here we present information about its appropriate use in physiological studies and possible clinical applications

The Place of the Hoplocarida in the Malacostracan Pantheon

The stomatopod body plan is highly specialized for predation, yet the Superorder Hoplocarida originated from something other than the lean, mean, killing machine seen today. The fossil record of the group indicates that it originated early on from a non-raptorial ancestor, with the specialized predatory morphology developing much later. The Recent Hoplocarida have been variously positioned within the Malacostraca, from a Subclass equal in rank to the Eumalacostraca (= Caridoida) to being placed as a Superorder within the Eumalacostraca. Consideration of the early fossil morphology, especially of the form of the carapace, of the position and functioning of the articles in the last three pairs of thoracopods, and of other features, suggests that hoplocarids are early derivatives of a basal eumalacostracan stock that was shrimp-like in form. The enhancement of an abdominal respiratory system most likely allowed the development of the anterior thorax into the specialized raptorial system present today