The impact of ICT on work–life experiences among university Teaching Assistants

Email is now commonplace in the university environment, but little research has addressed the impact of this technology on the work–life experiences of Teaching Assistants (TAs). These workers are of interest as they are typically responsible for most day-to-day, routine interaction with undergraduates, for ensuring students understand lectures and other course materials, and for assessing student work. In the summer of 2006, we undertook a web-based survey of Teaching Assistants at a major Canadian university. We wanted to examine the impact of and experience with information and communication technologies (ICTs) – in this case, the ubiquitous email. We found that these academic workers made extensive use of email, and that their experiences and attitudes were mixed. While relatively few expressed a desire to completely eliminate email use in their practice, problems such as feeling ‘overburdened’ by student email were common. Respondents who had set in-person office hours were twice as likely to assert that email increased their workload, that they felt overburdened by student email, and that they preferred not to communicate with students over email. There were also unexpected differences among TAs in the arts/social sciences compared to those in the math/science disciplines. Our data calls into question the largely optimistic orientation common in research reporting at the nexus point of education and ICTs, and suggests that an approach that is both critical and constructive is warranted when thinking about technology and academic work–life.     

Optimization of a lattice Boltzmann computation on state-of-the-art multicore platforms

We present an auto-tuning approach to optimize application performance on emerging multicore architectures. The methodology extends the idea of search-based performance optimizations, popular in linear algebra and FFT libraries, to application-specific computational kernels. Our work applies this strategy to a lattice Boltzmann application (LBMHD) that historically has made poor use of scalar microprocessors due to its complex data structures and memory access patterns. We explore one of the broadest sets of multicore architectures in the high-performance computing (HPC) literature, including the Intel Xeon E5345 (Clovertown), AMD Opteron 2214 (Santa Rosa), AMD Opteron 2356 (Barcelona), Sun T5140 T2+ (Victoria Falls), as well as a QS20 IBM Cell Blade. Rather than hand-tuning LBMHD for each system, we develop a code generator that allows us to identify a highly optimized version for each platform, while amortizing the human programming effort. Results show that our auto-tuned LBMHD application achieves up to a 15 times improvement compared with the original code at a given concurrency. Additionally, we present a detailed analysis of each optimization, which reveals surprising hardware bottlenecks and software challenges for future multicore systems and applications.     

A powerful combinatorial screen to identify high-affinity terbium(III)-binding peptides

Lanthanide-binding tags (LBTs) are protein fusion partners consisting of encoded amino acids that bind lanthanide ions with high affinity. Herein, we present a new screening methodology for the identification of new LBT sequences with high affinity for Tb(3+) ions and intense luminescence properties. This methodology utilizes solid-phase split-and-pool combinatorial peptide synthesis. Orthogonally cleavable linkers allow an efficient two-step screening procedure. The initial screen avoids the interference caused by on-bead screening by photochemically releasing a portion of the peptides into an agarose matrix for evaluation. The secondary screen further characterizes each winning sequence in a defined aqueous solution. Employment of this methodology on a series of focused combinatorial libraries yielded a linear peptide sequence of 17 encoded amino acids that demonstrated a 140-fold increase in affinity (57 nM dissociation constant, K(D)) over previously reported lanthanide-binding peptides. This linear sequence was macrocyclized by introducing a disulfide bond between flanking cysteine residues to produce a peptide with a 2-nM apparent dissociation constant for Tb(3+) ions.Supporting information for this article is available on the WWW under http://www.chemphyschem.org or from the author.     

Use of sex pheromone, 2,6-dichlorophenol,to disrupt mating by american dog tickDermacentor variabilis (SAY)

Treatment ofD. variabilis-infested dogs with formulations of the sex pheromone, 2,6-dichlorophenol, significantly reduced mating by the attached ticks. Aqueous emulsions of a gelatin microcapsule-xylene slurry and a pheromone-loaded, molecular-sieve powder were used. Concentration was an important variable influencing product efficacy. Such formulations combined with an acaricide may prove effective in reducing tick populations on livestock and pets.Supported by grants, AI 10,986 and AI 10,987 from the Institute of Allergy and Infectious Diseases, National Institute of Health, U.S. Public Health Service, DHEW, Bethesda, Maryland 20205.     

A comparison of the biological properties of of androst-5-en-3β-ol,a series of (20R)-n-alkylpregn-5-en-3β-ols and 21-isopentylcholesterol with those of cholesterol

The Δ⁵-sterol, androst-5-en-3β-ol, which has no side chain at C-17, did not permit molting of the insectHeliothis zea, growth of either the protozoanTetrahymena pyriformis, or the yeastSaccharomyces cerevisiae adapted to anaerobic conditions, nor was the sterol esterified by a mammalian microsomal ACAT preparation. However, the sterol did form a liposome with egg lecithin and, when fed to mice, did inhibit hepatic cholesterol synthesis. 21-Isopentylcholesterol also formed a liposome but neither supported the growth of the yeast nor was metabolized by the protozoan. When sterols, 20(R)-n-alkylpregn-5-en-3β-ols, with side chains of varying lengths were added to the medium of the protozoan, maximal esterification with fatty acids occurred with the 20(R)-n-pentyl derivative, and maximal inhibition of tetrahymanol formation occurred with then-butyl,n-pentyl andn-hexyl derivatives. In all of the assays, cholesterol showed a positive response, either permitting molting or growth, being metabolized, inhibiting sterol or tetrahymanol synthesis, or forming a liposome.     

Errors in the heat of battle: taking a closer look at shared cognition breakdowns through teamwork

OBJECTIVE: We developed a theoretically based taxonomy for classifying shared cognition breakdowns related to teamwork which contribute to fratricide incidents. BACKGROUND: Fratricide on the battlefield is an inescapable cost of war. A number of technological advancements have been made in terms of combat identification systems to reduce the risk of these incidents. However, fratricide continues to occur at alarming rates. METHOD: We take a human-centered approach to understanding errors leading to fratricide incidents by focusing on shared cognition. We turn to the literature and provide the theoretical foundations for an error classification taxonomy to improve understanding of why fratricide incidents occur. RESULTS: Based on our review of the literature, we identified a number of problem areas leading to fratricide incidents. However, many of the cited contributing factors were broad terms (e.g., poor coordination) and did little to tell us why the breakdown occurred and where improvements are needed. Therefore, we chose to focus on one specific area--teamwork breakdowns--and discuss in depth how these breakdowns contribute to fratricide. CONCLUSION: In this paper, we take a first step toward proposing a taxonomy that allows for the diagnostic assessment of what causes teamwork breakdowns in fratricide. We understand that a taxonomy is only as good as the data available and encourage richer case studies from which to learn. APPLICATION: To apply this taxonomy in an operational setting, we provide a set of behavioral markers that can be used to identify teamwork breakdowns on the battlefield.     

A statistics-based approach to binary image registration with uncertainty analysis

A new technique is described for the registration of edge-detected images. While an extensive literature exists on the problem of image registration, few of the current approaches include a well-defined measure of the statistical confidence associated with the solution. Such a measure is essential for many autonomous applications, where registration solutions that are dubious (involving poorly focused images or terrain that is obscured by clouds) must be distinguished from those that are reliable (based on clear images of highly structured scenes). The technique developed herein utilizes straightforward edge pixel matching to determine the "best" among a class of candidate translations. A well-established statistical procedure, the McNemar test, is then applied to identify which other candidate solutions are not significantly worse than the best solution. This allows for the construction of confidence regions in the space of the registration parameters. The approach is validated through a simulation study and examples are provided of its application in numerous challenging scenarios. While the algorithm is limited to solving for two-dimensional translations, its use in validating solutions to higher-order (rigid body, affine) transformation problems is demonstrated     

The Growth‐Inhibiting Effects of Beef Fatty Acids on MCF‐7 Cells Are Influenced Mostly by the Depot Location and Inconsistently by the Biohydrogenation Intermediate Content

Biohydrogenation intermediates (BHI) including conjugated linoleic acid (CLA) isomers are formed during ruminal biohydrogenation of polyunsaturated fatty acids (PUFA) in ruminants. Although many studies have examined the anticarcinogenic effects of CLA, few studies have reported the anticarcinogenic properties of BHI in their natural form found in dairy and beef fats. The present study compared the growth‐inhibitory effects of fatty acids from beef perirenal fat (PRF) or subcutaneous fat (SCF) with low or high levels of BHI in MCF‐7 human breast cancer cells. Cells were exposed for 72 h to media containing increasing doses (50 to 400 μM) of different beef fat treatments. Fatty‐acid analysis showed that BHI were readily incorporated into cell phospholipids (PL) in a treatment‐dependent manner, but higher BHI in PL did not consistently inhibit growth. Culturing with low‐BHI PRF or high‐BHI PRF did not lead to growth inhibition, but low‐BHI SCF inhibited growth, and inhibition was further increased by high‐BHI SCF. Other classes of fatty acids may, therefore, be interacting with BHI resulting in differential effects on growth inhibition in human breast cancer cells.     

Peroxidation reactions in plant membranes: Effects of free fatty acids

Free fatty acids accumulate in plant membranes after exposure of plants to environmental stress, such as freezing and desiccation. Fatty acid accumulation has been linked to various biophysical changes and to the occurrence of lipid peroxidation, but the relationships appear complex and inconsistent. The interactions between oxygen free radicals, free fatty acids and lipid peroxidation in plant membranes were examined further by studying peroxidation reactions in a model membrane system composed of a complex mixture of plant phospholipids, including various free fatty acids. Multilamellar liposomes were treated with oxygen free radicals generated from iron ascorbate. Increased concentrations of free palmitic acid up to 10 mol% (fatty acid/phospholipid) reduced the production of aldehydes detected by the thiobarbituric acid assay, but enhanced the production of fluorescent products. By contrast, increased concentrations of free linolenic acid increased aldehyde production and reduced the formation of fluorescent products. The two free fatty acids both enhanced the susceptibility of phospholipids to degradation as shown by the reduced recovery of esterified polyunsaturated fatty acids (linoleic and linolenic). The free radical reactions with or without free fatty acid additions catalyzed the selective degradation of phospholipids in the order phosphatidylethanolamine > phosphatidylcholine > phosphatidylinositol > phosphatidylglycerol. Selective degradation of phospholipids is often observed after periods of environmental stress or during senescence of plants, and has been cited as evidence for the involvement of phospholipases in these degenerative processes. The results indicate that selectivity is not a criterion for eliminating the involvement of oxygen free radicals in these degenerative processes. Furthermore, the results suggest that modifications of lipid composition during a plant's acclimation to adverse environments may determine the types of free radical reactions that occur due to stress.     

Iterative design of a semi-autonomous social telepresence robot research platform: a chronology

Our research focuses on how a telepresence robot operator, the people with the robot, and the robot itself collaborate so that the operator reaches his/her intended destination. Our research requires higher levels of autonomous navigation so that the robot can, for example, go to a specified destination and follow a person. However, commercial telepresence robots are primarily teleoperated, and only a few provide assisted navigation around obstacles. Our system must include sensors and processing to enable these capabilities. We present the chronology of our iterative design for augmenting two VGo Communications’ VGo robots, Hugo and Margo, over a period of 3 years. We detail the requirements and design constraints encountered while developing our telepresence robot platforms.