The effects of stimulus modality and task integrality: Predicting dual-task performance and workload from single-task levels

The influence of stimulus modality and task difficulty on workload and performance was investigated. The goal was to quantify the cost (in terms of response time and experienced workload) incurred when essentially serial task components shared common elements (e.g., the response to one initiated the other) which could be accomplished in parallel. The experimental tasks were based on the Fittsberg paradigm; the solution to a SternBERG-type memory task determines which of two identical FITTS targets are acquired. Previous research suggested that such functionally integrated dual tasks are performed with substantially less workload and faster response times than would be predicted by suming single-task components when both are presented in the same stimulus modality (visual). The physical integration of task elements was varied (although their functional relationship remained the same) to determine whether dual-task facilitation would persist if task components were presented in different sensory modalities. Again, it was found that the cost of performing the two-stage task was considerably less than the sum of component single-task levels when both were presented visually. Less facilitation was found when task elements were presented in different sensory modalities. These results suggest the importance of distinguishing between concurrent tasks that complete for limited resources from those that beneficially share common resources when selecting the stimulus modalities for information displays

The Identification of cis-II, I2-Methylene-2-hydroxyoctadecanoic Acid from \u3ci\u3eThiobacillus thiooxidans\u3c/i\u3e

A polar fatty acid has been observed as a component of an ornithine-containing lipid of Thiobacillus thiooxidans. A comparison of thin layer chromatographic mobilities of reference compounds to those of the natural acid and its derivatives suggested that the acid was a 2-hydroxy fatty acid. The presence of a cyclopropane function in the acid was indicated by l4e-Iabeling experiments and infrared spectroscopy. Mass spectrometry of the methyl ester and the acetylated methyl ester of the natural acid provided a molecular weight for the acid. Equivalent chain lengths were determined for the natural acid, the acid obtained by oxidative decarboxylation of the natural acid with permanganate, and the acids derived through reductive ring cleavage of the cyclopropane group in the ester of the oxidatively decarboxylated natural acid. The mass spectral data, the equivalent chain length determinations, and the permanganate oxidation study clearly indicated that the acid possessed an 18- carbon chain with a methylene bridge and a 2-hydroxyl function. The equivalent chain length determinations further suggested that the cyclopropane group had the cis configuration. Mass spectrographic analysis of the branched chain esters obtained by reductive cleavage of the ester which was in turn derived through oxidative decarboxylation of the natural acid allowed the assignment of the 11,12 position for the cyclopropane group. Based on these data, the polar acid is proposed to be cis-ll, 12-methylene-2- hydroxyoctadecanoic acid

Phospholipids of \u3ci\u3eThiobacillus thiooxidans\u3c/i\u3e

Cells and spent growth media from sulfur- and thiosulfate-grown cultures of Thiobacillus thiooxidans were analyzed. The phosphatides were examined by thinlayer chromatography, and the products of their hydrolysis by hydrochloric acid and methanolic potassium hydroxide were separated by paper chromatography. The phospholipids in both cells and spent growth media were identified as phosphatidyl ethanolamine, phosphatidyl N-monomethylethanolamine, phosphatidyl glycerol, and diphosphatidyl glycerol. These comprised about 97% of the total lipid phosphorus. Lyso-phosphatidyl-N-monomethylethanolamine and lysophosphatidylglycerol accounted for the remaining 3%. The percentage of the total lipid phosphorus accounted for by each phospholipid depended on the age of the culture

Professionalizing TA Training: Commitment to Teaching or Rhetorical Response to Market Crisis?

Although English Studies as a discipline is often seen as fractured and contentious, there is one subject about which most of us can agree: the job market for new PhDs in English is bad and not likely to improve any time soon. In Bettina Huber’s widely cited survey of the results of the 1993-1994 job search, only 45.9% of candidates found tenure-track jobs. The recent report from the MLA Committee on Professional Employment projects similar figures for the foreseeable future. The fact that the number of graduate students with PhDs in English—especially those with concentrations in literary studies or creative writing—far exceeds the number of jobs available has led to such competition among prospective job candidates that “wise” graduate students begin putting together a professional career from the moment they are accepted into graduate school, and those who work with graduate students are admonished to support them in this professionalizing process (Mangum, Pemberton, Wolfsom). Analyses of the job crisis differ, as do proposed solutions, but again, most commentators agree that if new PhDs want to have a chance at tenure-track employment, then everyone—graduate students and their mentors—needs to do more and do it better. The “more” that graduate students need to do usually refers to activities associated with being a research scholar such as publishing articles and giving conference presen¬tations. But there is some recognition that professionalization should go beyond publication of research to include the professional representation of one’s teaching, administrative work, and academic service. Because we recognize the highly contingent nature of graduate students’ experiences with professionalization at the different institutions in which they work and those they seek to enter, we hesitate to make sweeping recommendations about the role TA training should play in preparing graduate students to be professionals. What we would like to offer, rather, are some cautions. First, we believe that WPAs and those who work with graduate students need to recognize that calls for increased professional¬ization often implicitly—if unintentionally—lay blame on graduate students rather than on the market economy in which there are too few jobs. While it may be true that some graduate students are unprepared for the professional duties required of newly hired tenure-track faculty, our experiences suggest that graduate students generally are professionals, especially in their classrooms, even though they are often not rewarded as such. WPAs also should be wary of how arguments for professional development for graduate students can be used to dismantle TA preparation programs that emphasize pedagogy. There must be a balance between inviting other faculty to participate in the professionalization of graduate students and maintaining spaces for discussions about pedagogy that focus on teacher professionalism. Lastly, those who do genuinely seek to professionalize TA training on the basis of public calls for reform need to acknowledge that utilizing the language of research, while perhaps persuasive to members of a particular institution, might not go far enough in addressing the public’s larger concerns. While rhetoric is reality, the rhetoric of educational decline which speaks to a wide audience seems ultimately more powerful than the rhetoric of professionalization, addressed to a much narrower audience of academics with, some might say, overly narrow concerns. Until there is more critical engagement about what the professionalization of teaching is for, what it seeks to do, and how it benefits students in the classroom, the discourses of professionalization will seem more a rhetorical response to a market crisis than a genuine expression of a commitment to teaching. Perhaps the most important contribution WPAs can make to graduate students’ professional development is to provide them with opportunities for such critical engagement

Excitonic pairing between nodal fermions

We study excitonic pairing in nodal fermion systems characterized by a vanishing quasiparticle density of states at the pointlike Fermi surface and a concomitant lack of screening for long-range interactions. By solving the gap equation for the excitonic order parameter, we obtain a critical value of the interaction strength for a variety of power-law interactions and densities of states. We compute the free energy and analyze possible phase transitions, thus shedding further light on the unusual pairing properties of this peculiar class of strongly correlated systems.Comment: 9 pages, 7 figures, minor revisions made, final versio

An integrated approach to rotorcraft human factors research

As the potential of civil and military helicopters has increased, more complex and demanding missions in increasingly hostile environments have been required. Users, designers, and manufacturers have an urgent need for information about human behavior and function to create systems that take advantage of human capabilities, without overloading them. Because there is a large gap between what is known about human behavior and the information needed to predict pilot workload and performance in the complex missions projected for pilots of advanced helicopters, Army and NASA scientists are actively engaged in Human Factors Research at Ames. The research ranges from laboratory experiments to computational modeling, simulation evaluation, and inflight testing. Information obtained in highly controlled but simpler environments generates predictions which can be tested in more realistic situations. These results are used, in turn, to refine theoretical models, provide the focus for subsequent research, and ensure operational relevance, while maintaining predictive advantages. The advantages and disadvantages of each type of research are described along with examples of experimental results

Analysis of microstrip patch antennas with nonzero surface resistance

The scattering properties of a microstrip patch antenna with nonzero surface impedance are examined. The electric field integral equation for a current element on a grounded dielectric slab is developed for a rectangular geometry by using Galerkin's technique with subdomain piecewise linear basis functions. The integral equation includes a resistive boundary condition on the surface of the patch. The incident field on the patch is expressed as a function of incidence angle. The resulting system of equations is then solved for the unknown current modes on the patch, and the radar cross section is calculated for a given scattering angle. Theoretical results in the form of radar cross section as a function of frequency are compared with results measured at the NASA Langley Research Center

The Effects of a Remote Control Tactile Feedback System on Conversation Skills in Children with Autism.

A few studies have examined the effects of a remote control tactile device (RCT) as an unobtrusive prompting method used to promote skills such as verbal initiations and play behaviors in children with autism. To date, however, no published studies have investigated the effects of the RCT as a consequence to increase and maintain conversation skills. This study was designed to determine whether the RCT, in conjunction with common training techniques (i.e. roleplays, visual feedback, and sibling coaching), could be used as a discrete and unobtrusive feedback system to promote conversation skills in high functioning children with autism. Results found that the RCT and training packages were effective in initially increasing rates of target responses. The effects however, did not always maintain with a return to baseline. Programming "naturally" maintaining communities of reinforcement was found to be a critical factor in the maintenance of the conversational responses