bluuebunny/crossref_metadata_2025 huggingface dataset:
A murine respiratory-inducing niche displays variable efficiency across human and mouse embryonic stem cell species
Authors: Denham Mark , Conley Brock J. , Olsson Fredrik , Gulluyan Lerna , Cole Timothy J. , Mollard Richard
Published: January 2007

Human embryonic stemlike cells (hESCs) are pluripotent cells derived from blastocysts. Differentiating hESCs into respiratory lineages may benefit respiratory therapeutic programs. We previously demonstrated that 24% of all mouse embryonic stem cell (mESC) derivatives cocultured with embryonic day 11.5 (E11.5) mouse lung rudiments display immunoreactivity to the pneumonocyte II specific marker surfactant-associated protein C (Sftpc). Here we further investigate the effects of this inductive niche in terms of its competence to induce hESC derivative SFTPC immunoreactivity and the expression of other markers of terminal lung secretory units. When hESCs were cocultured as single cells, clumps of ∼10 cells or embryoid bodies (EBs), hESC derivatives formed pan-keratin-positive epithelial tubules at high frequency (>30% of all hESC derivatives). However, human-specific SFTPC immunoreactivity associated with tubule formation only at low frequency (<0.1% of all hESC derivatives). Human-specific SFTPD and secretoglobin family 1A member 1 ( SCGB1A1, also known as CC10) transcripts were detected by PCR after prolonged culture. Expression of other terminal lung secretory unit markers ( TITF1, SFTPA, and SFTPB) was not detected at any time point analyzed. On the other hand, hESC derivatives cultured as plated EBs in media previously demonstrated to induce Sftpc expression in isolated mouse fetal tracheal epithelium expressed all terminal lung secretory unit markers examined. mESCs and hESCs thus display fundamental differences in their response to the E11.5 mouse lung inductive niche, and these data provide an important step in the delineation of signaling mechanisms capable of efficiently inducing hESC differentiation into terminal secretory units of the lung.
Yin Yang 1 enhancescyclooxygenase-2gene expression in macrophages
Authors: Joo Myungsoo , Wright Jeffrey G. , Hu Ning Ning , Sadikot Ruxana T. , Park Gye Young , Blackwell Timothy S. , Christman John W.
Published: January 2007

Expression of cyclooxygenase-2 (COX-2) is associated with the pathogenesis of inflammation and various cancers, including lung cancer. Yin Yang 1 (YY1) is a zinc-finger transcription factor that interacts with histone acetyltransferases and deacetylases for its transcriptional activity and also is involved in inflammation and tumorigenesis. We investigated whether YY1 regulates COX-2 expression. We located a possible YY1 binding site proximal to the transcription initiation site of the COX-2 promoter. Electrophoretic mobility shift assays show that YY1 bound to the putative YY1 site in vitro. To show biological relevance, we performed chromatin immunoprecipitation assays showing that lipopolysaccharide (LPS) treatment induced YY1 binding to the cognate site in the endogenous COX-2 promoter. Overexpression of YY1 in macrophages treated with either LPS or live Pseudomonas aeruginosa increased COX-2 transcriptional activity. Furthermore, YY1 enhanced COX-2 protein expression and prostaglandin D2production elicited by LPS treatment. Mechanistically, we observed that LPS treatment resulted in disruption of an interaction between YY1 and p300, a histone acetyltransferase, but did not affect the interaction between YY1 and histone deacetylase 1/2. These data suggest that in response to LPS, YY1 dissociates from p300 and binds to the COX-2 promoter, contributing to COX-2 expression in an inflammatory milieu.
Kinetic Painting: The Lumidyne System
Authors: Malina Frank J.
Published: January 2007

The paper discusses briefly kinetic painting systems that have been devised for producing a pictorial composition on a transluscent flat surface that changes with time without resorting to the projection of light through film in a darkened room. The Lumidyne system developed by the author in 1956 is described in detail. Basic principles of its design, together with variations of the system, are given as well as the method of painting used by the author. Examples of several works are shown. The picture produced by the system is considered from the point of view of real motion and of change of transparent colour with time. The need for aesthetic guide lines for the kinetic painter is stressed. The author concludes that the Lumidyne system, after ten years of experience with it, as a practical, controllable and economical artistic medium.
Papermaking properties of the ECF-bleached kraft pulps from first-thinning Scots pine (Pinus sylvestris L.)
Authors: Rautiainen Riikka , Alén Raimo
Published: January 2007

First-thinning Scots pine (Pinus sylvestris) and the outer (containing long fibers) and inner (containing short fibers) parts of its stem wood were delignified on a laboratory scale by kraft pulping followed by oxygen-alkali delignification and bleaching with D0(EO)D1(EP)D2. The aim was to evaluate the potential use of the bleached pulps as reinforcing material in various mechanical and chemical pulps. The physical and optical properties of the pulps indicated that only the “outer part pulp”, with rather similar properties to those of a reference softwood kraft pulp, seemed suitable for this purpose. In contrast, materials from first-thinning stem wood and its inner part resulted in lower yields as early as the kraft pulping stage. Rather mediocre strength properties were obtained, but the bleached kraft pulps prepared from the two first thinning-based materials had good optical properties.
Syntheses and properties of liquefied products of ozone treated wood/epoxy resins having high wood contents
Authors: Asano Toshiyuki , Kobayashi Masahiko , Tomita Bunichiro , Kajiyama Mikio
Published: January 2007

Liquefied products with high wood content were prepared by pretreating wood with ozone before liquefaction. As a result, the ratio of wood to polyhydric alcohol (W/P ratio) used as solvent could be increased to 2:1. Resin blends were prepared by mixing liquefied products with ethylene glycol diglycidyl ether (EGDGE, water-soluble) and diglycidyl ether of bisphenol A (DGEBA, oily consistency). The wood content of the resin blend could be increased to 53%. The resins were cured by citric acid or triethylene tetramine (TETA), and their mechanical properties were evaluated. Dynamic mechanical measurements revealed that the former had higher glass transition temperatures than the latter. It was found that the resin with DGEBA cured by citric acid had almost the same level of tensile strength as commercial plastics.
Dynamic mechanical analysis of dry wood: Linear viscoelastic response region and effects of minor moisture changes
Authors: Sun Nanjian , Das Sudipto , Frazier Charles E.
Published: January 2007

The dynamic mechanical analysis (DMA) of wood with moisture content (MC) below 1% has not yet been described. Aiming at this low MC range, the linear viscoelastic response region (LVR) of thoroughly dried wood was studied in single-cantilever bending. The LVR limit was determined as a function of grain orientation and temperature using yellow-poplar (Liriodendron tulipifera) and southern yellow pine(Pinusspp.). The LVR limit for dry wood ranged from approximately 0.03% to 0.16% strain. The LVR limit was greater for bending perpendicular to the grain than for parallel to the grain, suggesting that DMA signal quality would be better in the former case. Southern pine generally exhibited a greater LVR limit than yellow-poplar. The LVR anisotropy was greater in yellow-poplar than in southern pine. These findings suggest that detailed LVR analysis might be useful for wood analysis, or at least that regular LVR analysis is required for reliable wood DMA. The effects of wood moisture changes (between 0% and 1%) were observed in low-temperature secondary relaxations, consistent with the previous findings of others. Yellow-poplar specimens exhibited a significant storage modulus increase over a 250°C temperature range when specimen moisture increased from 0% to ∼0.7%.
Penetration of amino-silicone micro- and macro-emulsions into Scots pine sapwood and the effect on water-related properties
Authors: Weigenand Oliver , Militz Holger , Tingaut Philippe , Sèbe Gilles , de Jeso Bernard , Mai Carsten
Published: January 2007

An amino-silicone in the form of a micro- and a macro-emulsion (average particle size 40 and 120 nm, respectively) was tested in impregnation of solid wood. During vacuum-pressure impregnation, the uptake of 5% emulsions was only slightly reduced compared to water up-take. At 15% concentration, a significant reduction in emulsion uptake was observed, particularly in the radial and tangential directions of the wood. The penetration of silicone into the cell wall was dependent on the particle size of the emulsion. Applied as a macro-emulsion, a maximum of only 14% of the total silicone penetrated the cell wall, whereas 25–35% of the silicone was found in the cell wall when applied as a micro-emulsion. The degree of cell wall penetration of silicone for the micro-emulsion was confirmed by X-ray micro-analysis (SEM-EDX). The penetrated silicone caused bulking and dimensional stability. 1H NMR relaxometry T
2 distributions were determined for dried and moisture-conditioned wood samples. The silicone-treated specimens displayed spin-spin interactions of protons from water and silicones (or their emulsifiers). Conditioning of samples at 25°C and 65% relative humidity appeared to cause a decrease in the mobility of the non-water protons of the silicone and/or emulsifier. Freezing to -5°C caused separation of protons from bound water and from the silicone at low relaxation times. It is assumed that treatment with the micro-emulsion reduced water sorption due to micro-pore blocking in the cell wall. The formation of a sandwich complex is postulated, which comprises cell wall polymers, water molecules and a layer of silicone.
Search for a relationship between stress wave velocity and internal stresses in eucalypts and radiata pine
Authors: Chauhan Shakti S. , Entwistle Kenneth M. , Walker John C.F.
Published: January 2007

The relation between growth stress and stress wave velocity has been investigated on standing trees of Eucalyptus nitens. Longitudinal growth stress and the stress wave velocity were measured at breast height on 155 trees. Large variation in both growth strain and acoustic velocity was observed. The initial investigation with 34 trees showed good correlation (R2=0.68). Measurements on all 155 trees revealed no reliable relationship (R2=0.05). The influence of internal stress on acoustic velocity has also been investigated on radiata pine boards loaded in bending and tension. It was observed that the resonance frequencies were influenced by the position of loaded supports in bending, but were not affected by the bending load. In boards under tensile stresses, there was no change in acoustic velocity measured by the pulse transit time. The two experimental series, one on standing trees with water-filled lumens and the other on air-dried boards, failed to reveal any dependence of the stress wave velocity on growth stress. No valid basis therefore exists for the use of stress wave velocity to determine growth stress levels in either standing trees or in seasoned wood.
Kiln-drying lumber quality of hybrid poplar clones
Authors: Kang Kyu-Young , Bradic Slobodan , Avramidis Stavros , Mansfield Shawn D.
Published: January 2007

Hybrid poplars are currently used in North America primarily for the production of pulp fibre and in the manufacture of engineered solid wood products. Recently, the deployment of poplars as a short-rotation fibre crop has been of interest to mitigate the increasing amount of plantation-grown short fibre resources (hardwoods) derived from the Southern Hemisphere, as well as in the context of global climate change, both as a means to rapidly sequester carbon and as a feedstock for potential bioenergy production. Knowledge on the utility of hybrid poplars in the value-added secondary wood-processing sector, however, is very limited. To improve this situation, the variation in kiln-drying quality of five hybrid poplar genotypes of similar age, harvested from a common site in British Columbia, Canada, was evaluated for three different kiln-drying schedules. The results clearly demonstrate that the drying schedule has a greater effect on grade recovery and the degree of deformation than the hybrid poplar genotype. Furthermore, it was shown that many of the deformations inherently associated with wood derived from fast-grown trees can be reduced or removed with drying, in particular with an aggressive drying schedule.
Heat and mass transfer in wood composite panels during hot pressing: Part 4. Experimental investigation and model validation
Authors: Dai Chunping , Yu Changming , Xu Changyan , He Guangbo
Published: January 2007

The effects of panel density and strand size on the temperature and gas pressure inside strand mats during hot pressing has been experimentally investigated. The results show good agreement with model predictions. Strand dimensions have a strong effect on the core temperature and gas pressure when the mat/panel density is relatively high. At lower density, the temperature and gas pressure are controlled only by the panel density. Comparison between the model predictions and experimental results also reveals the need for further characterisation of the basic mat properties, especially conductivity and permeability.
Dielectric relaxation of water adsorbed on wood and charcoal
Authors: Sugimoto Hiroyuki , Kanayama Kozo , Norimoto Misato
Published: January 2007

The dielectric relaxation due to motions of water molecules adsorbed on wood treated at various temperatures up to 550°C was investigated based on the relationships between activation enthalpy (ΔH) and entropy (ΔS) in relaxation. The relationships indicated two straight lines with different slopes, depending on the treatment temperature. Given the same ΔS, ΔHvalues for water molecules adsorbed on wood treated at temperatures below 400°C were greater than for those treated above 450°C. It was considered that before heat treatment, water molecules were adsorbed mainly on hydroxyl groups by strong hydrogen bonds and formed ice-like structures. On the other hand, hydroxyl groups were not detected in wood after heat treatments above 400°C. We assume that water molecules are condensed in nanometer-scale micropores that are formed during the carbonization of wood. The relationship between ΔHand ΔSfor the motion of water adsorbed on wood treated above 450°C was similar to the value extrapolated from that for bulk water at temperatures below 0°C. We suggest that water molecules are adsorbed on charcoal in a supercooled state.
Workplace Changes Associated with a Reduction in Musculoskeletal Symptoms in Office Workers
Authors: Nelson Nancy A. , Silverstein Barbara A.
Published: January 2007

The purpose of this study was to identify factors associated with reductions observed in musculoskeletal symptoms when office workers were moved to a new building. A questionnaire including items regarding symptoms and aspects of the work environment was administered to 577 office workers before and after they were moved from nine buildings to a single new facility in 1992. Employees working in two reference buildings, where they remained throughout the study period, were also surveyed. Two musculoskeletal outcomes, hand/arm and neck/shoulder/back, were selected for study. In matched multivariate analyses, the reduction in hand/arm symptoms from 1992 to 1993 was associated with improved satisfaction with the physical workstation (odds ratio [OR] = 2.0); the reduction in neck/shoulder/back symptoms was associated with improved chair comfort (OR = 1.8), fewer housekeeping responsibilities (OR = 3.6), female gender (OR = 1.8), and low pay range (OR = 1.7). Longitudinal results suggested that changes in workstations resulted in decreased symptoms. Results of this investigation might be used to develop workplace changes that result in reductions of musculoskeletal disorders
Effects of Practice and Learner Control on Short-and Long-Term Gain and Efficiency
Authors: Shute Valerie J. , Gawlick Lisa A. , Gluck Kevin A.
Published: January 2007

This study investigated the effects of practice opportunities and learner control on short- and long-term learning from a computer-based introductory statistics curriculum. In all, 380 participants were assigned to one of five conditions. The first four conditions differed in terms of the number of problems to solve per problem set. The fifth condition allowed learners to choose the amount of practice. A subset (n = 120) of the original participants returned for testing following a six-month interval. Overall, the fixed-practice conditions showed learning gains that varied in relation to the amount of practice (i.e., more was better). The data from the learner-control condition was unexpected, showing learning gains comparable with the most extended practice condition yet the fastest tutor-completion times. We discuss implications of these findings in relation to the design of efficacious instruction. Actual or potential applications of this research include the modification of computer-based instruction that can enhance individuals′ learning efficiency and outcome scores.
Comprehension of Pictorial Symbols: Effects of Context and Test Method
Authors: Wolff Jennifer Snow , Wogalter Michael S.
Published: January 2007

This research examined two factors involved in the evaluation of pictorial symbol comprehension: context (absence vs. presence of photographs depicting the probable environments where a symbol would be seen) and test method (multiple-choice with less vs. more plausible distractor alternatives vs. open-ended). We tested 33 pictorial symbols from various sources. The results showed that the multiple-choice test with less plausible distractors inflated comprehension scores by an average of 30% compared with the other two tests, which did not differ. The presence of context increased symbol comprehension in the open-ended test and in the multiple-choice test that had more plausible distractors. Extensive preliminary procedures demonstrated the difficulty of forming a multiple-choice test with plausible distractor alternatives. This fact, combined with multiple-choice tests′ low ecological validity in reflecting the real-world task of symbol comprehension, suggests that this test should be avoided in favor of an open-ended testing procedure. It is suggested that context provides ecologically valid cues that limit the range of possible constructs that the pictorial symbol could be, raising comprehension scores. The use of context may help reduce the costs (money, time, effort) of producing pictorial symbols with acceptable, above-criterion comprehension levels.
Use of the Critical Decision Method to Elicit Expert Knowledge: A Case Study in the Methodology of Cognitive Task Analysis
Authors: Hoffman Robert R. , Crandall Beth , Shadbolt Nigel
Published: January 2007

The Critical Decision Method (CDM) is an approach to cognitive task analysis. The method involves multiple-pass event retrospection guided by probe questions. The CDM has been used in the elicitation of expert knowledge in diverse domains and for applications including system development and instructional design. The CDM research illustrates the sorts of knowledge representation products that can arise from cognitive task analysis (e.g., Situation Assessment Records, time lines, decision requirements). The research also shows how one can approach methodological issues surrounding cognitive task analysis, including questions about data quality and method reliability, efficiency, and utility. As cognitive task analysis is used more widely in the elicitation, preservation, and dissemination of expert knowledge and is used more widely as the basis for the design of complex cognitive systems, and as projects move into even more field applications and real-world settings, the issues we discuss become increasingly critical.
Effects of a Split Keyboard Design and Wrist Rest on Performance, Posture, and Comfort
Authors: Smith Michael J. , Karsh Ben-Tzion , Conway Frank T. , Cohen William J. , James Craig A. , Morgan Jay J. , Sanders Katherine , Zehel David J.
Published: January 2007

The purpose of this study was to examine differences in experienced typists′ performance, posture, and musculoskeletal pain when using a split, adjustable (SA) computer keyboard and when using a standard flat keyboard. In addition, the use of a wrist rest was examined for performance, posture, and musculoskeletal pain effects. Eighteen participants were exposed to the SA keyboard and a flat keyboard in a laboratory study of text typing for four consecutive hours on five days. The results indicated that after just 2 h of orientation and practice, the participants could perform as well on the SA keyboard as on the flat keyboard. The SA keyboard provided advantages for reduced wrist/hand pronation. There was no difference between the keyboards in the level of musculoskeletal pain reported by participants after typing. However, they reported increased pain in the back, neck, shoulders, and wrists from the beginning to the end of each of the experimental periods for both keyboards
Cognitive Factors in the Close Visual and Magnetic Particle Inspection of Welds Underwater
Authors: Leach John , Morris Peter E.
Published: January 2007

Underwater close visual inspection (CVI) and magnetic particle inspection (MPI) are major components of the commercial diver's job of nondestructive testing and the maintenance of subsea structures. We explored the accuracy of CVI in Experiment 1 and that of MPI in Experiment 2 and observed high error rates (47% and 24%, respectively). Performance was strongly correlated with embedded figures and visual search tests and was unrelated to length of professional diving experience, formal inspection qualification, or age. Cognitive tests of memory for designs, spatial relations, dotted outlines, and block design failed to correlate with performance. Actual or potential applications of this research include more reliable inspection reporting, increased effectiveness from current inspection techniques, and directions for the refinement of subsea inspection equipment.
Continuous Haptic Information in Target Tracking from a Moving Platform
Authors: Korteling J. E. , Van Emmerik M. L.
Published: January 2007

The present study was conducted to gain insight into the effects of different forms of continuous haptic information (CHI) on operator performance with a moving unmanned platform. In a simulator experiment, participants tracked a moving target with a disturbed viewfinder (moving platform). While the participants performed this combined pursuit and compensatory tracking task, haptic information was provided to them concerning translatory disturbances of the platform. Two steering variables were manipulated between participants: presence or absence of CHI provided at the control device and automated or manual stabilization of the platform. The other factors were image degradation, motor task load, and visual task load. Haptic information was generated by movements of an active joystick that was used for steering the platform. It was shown that both CHI and platform stabilization substantially reduced tracking error. These effects were not additive; CHI improved tracking performance only when the platform was not stabilized, and it did not significantly degrade pursuit tracking performed with a stabilized viewfinder. The magnitude of the CHI effect was independent of image degradation, motor load, and visual load. CHI at the joystick improves tracking performance when it involves relevant control information; when it provides other information, tracking performance is only marginally degraded. Actual or potential applications of this research include performance of missions in environments that are difficult to access, potentially harmful to humans, or both, such as reconnaissance behind enemy lines, tracing of environmental pollution at sea, and assessment of damage in nuclear disaster areas.
Navigational Checking Using 3D Maps: The Influence of Elevation Angle, Azimuth, and Foreshortening
Authors: Schreiber Brian T. , Wickens Christopher D. , Renner Goetz J. , Alton Jeffrey D. , Hickox Joseph C.
Published: January 2007

Maps help navigators determine their position in the world. We define navigational checking as an aviator's task of continually comparing a map with the forward field of view (FFOV). We report two experiments using static three-dimensional (3D) images as the map and FFOV. Participants were asked to judge as quickly and accurately as possible whether the map and FFOV matched or mismatched. Elevation angle, azimuth angle, type of mismatch trial, and image complexity were manipulated; both response time and accuracy were recorded. Results were generally as predicted. Of greatest interest, we found a fairly linear performance decrement associated with the difference in foreshortening between the two views (a trigonometric conversion of elevation angle disparity), a somewhat nonlinear performance decrement associated with azimuth angle disparity, and no interaction between the two. Finally, we address how elevation and azimuth might influence 3D map display design.
Work Schedule and Task Factors in Upper-Extremity Fatigue
Authors: Rosa Roger R. , Bonnet Michael H. , Cole Libby L.
Published: January 2007

We tested the combined effects of work schedule and task factors on upper-extremity fatigue in the laboratory during 8-h and 12-h shift schedules. Participants performed a simulated manual assembly task at three repetition rates and three torque loads and self-adjusted their work cycle duration to maintain fatigue at moderate levels. Work cycle durations decreased with increases in both load level and repetition rate. Fatigue was observed more quickly with increasing time on shifts and during night shifts compared with day shifts. Work schedule effects were most apparent at lighter workloads, with minimal differences at higher workloads. The highest fatigue levels were observed during 12-h night shifts, with similar levels reached by the end of both the week of 8-h night shifts and the week of 12-h day shifts. Overall durations were 20%–30% shorter than in previous short-term studies, which was likely a result of the more realistic work schedules used in this study. Results from this study could be applied to the design of work-rest schedules for manual tasks involving the upper extremities.
Sound Localization: Information Theory Analysis
Authors: Wallace John S. , Fisher Donald L.
Published: January 2007

Sound localization has been studied extensively. Curiously, although much is known about factors that affect errors, little is known about factors that influence response time. Three experiments were performed in an attempt to identify the separate influence of each of several different factors. All trials used a single broadband noise signal emanating from one of a subset of six loudspeakers equally spaced around the participant in the azimuthal plane. Both the size of the subset and the balance of relative probabilities from speaker to speaker were altered to evaluate the relationship between information content and the dependent variable, choice reaction time. Choice reaction time was found to be related to the information content of the sound stimulus in all cases. It was also found to be related to the presence of pairs of speakers that were symmetrically opposed in front of and behind the participant. Models of choice reaction time in a sound localization task have clear implications for practice. For example, they suggest that multiple auditory collision warnings may endanger drivers.
Effects of Text Structure and Prior Knowledge of the Learner on Navigation in Hypertext
Authors: McDonald Sharon , Stevenson Rosemary J.
Published: January 2007

In this study we examined the effects of 3 hypertext topologies—hierarchical, nonlinear, and mixed (hierarchical structure with cross referential links)—on the navigation performance of participants with high and low prior knowledge of the text topic. After reading the text, participants used the document to find the answers to 10 questions. After a filled distraction period, participants returned to the document to answer 10 more questions. The results showed that participants in the mixed condition performed better than those in the other 2 conditions and that the performance of knowledgeable participants was superior to that of nonknowledgeable participants. These results are discussed in relation to the ways in which text structure interacts with background knowledge of the user in enhancing or impeding performance. Actual or potential applications of this research include the design and implementation of hypertext systems for users with different levels of familiarity with the subject matter of the text.
The Impact of Cross-Training and Workload on Team Functioning: A Replication and Extension of Initial Findings
Authors: Cannon-Bowers Janis A. , Salas Eduardo , Blickensderfer Elizabeth , Bowers Clint A.
Published: January 2007

Although previous research has shown that cross-training team members improves team performance, a number of questions remain concerning the nature of cross-training. The current study provides an extension of previous cross-training research by investigating two theoretical issues: the nature of cross-training and the joint impact of cross-training and workload on team functioning. The study examined 40 three-person teams performing a simulated radar task. Results indicated that positional rotation was an effective cross-training method for highly interdependent tasks, that cross-trained teams developed a greater degree of interpositional knowledge than did teams that were not cross-trained, and that cross-training was important only under high-workload performance conditions. The current study suggests that the type of cross-training necessary to improve team performance may be related to the nature of the task and that cross-training may be effective in allowing teams to coordinate implicitly—that is, without the need to communicate overtly. Taken together with previous work, the results of this study indicate strong support for the efficacy of cross-training as a means to help teams perform well. Potential applications of this research include training for military, medical, and aviation teams
Levels of Expertise and Instructional Design
Authors: Kalyuga Slava , Chandler Paul , Sweller John
Published: January 2007

Cognitive load theory assumes that information should be structured to eliminate any avoidable load on working memory in order to enhance learning. We hypothesized that the appropriate type of structure may depend on the learner's level of expertise. Less expert learners using a diagram might require the diagram to be physically integrated with related text-based information in order to reduce cognitive load. However, the same diagram might be intelligible in isolation by more experienced learners, who might require the elimination of redundant text to reduce cognitive load. The results of three experiments indicated that as level of expertise increased, the best instructional designs changed from ones in which diagrams and text were physically integrated to ones in which the text was eliminated.
Functional Limitations to Daily Living Tasks in the Aged: A Focus Group Analysis
Authors: Rogers Wendy A. , Meyer Beth , Walker Neff , Fisk Arthur D.
Published: January 2007

We assessed constraints on daily living of 59 healthy, active adults 65–88 years of age in focus group interviews. Individual comments about specific problems were coded along the dimensions of (a) the locus of the problem (motor, visual, auditory, cognitive, external, or health limitations); (b) the activity involved (e.g., transportation, leisure, housekeeping); (c) whether the problem was attributable to task difficulty or the perception of risk; and (d) response to limitations (perseverance, cessation, compensation, or self-improvement). The data provide information about the types of difficulties encountered in everyday activities as well as the way in which individuals respond to such difficulties. Each comment was also coded in terms of whether it was remediable via training, design changes, or some combination of the two. More than half of the problems that were reported had the potential to be improved in some way, thus providing direction for future research in human factors and aging. Actual or potential applications of this research include identifying problems and difficulties that older adults encounter in daily activities such as transportation and leisure; more specifically, determining the degree to which such problems are potentially remediable by human factors solutions. Applications of this research also include understanding the types of systems, products, and technologies that older adults interact with currently, or are interested in learning to use.
Binocular Virtual Reality Displays: When Problems Do and Don't Occur
Authors: Mon-Williams Mark , Wann John P.
Published: January 2007

It has been demonstrated that a stereoscopic virtual reality system can cause deficits of binocular vision but that a well-engineered bi-ocular (nonstereoscopic) display can avoid causing stress to the visual system. The stereoscopic depth information present in binocular displays has been hypothesized to be a contributing factor to visual stress. We undertook research to determine the effect of stereoscopic depth in virtual reality displays on the visual system and found that stereoscopic depth does not, per se, cause problems to binocular vision over short (10-min) viewing periods. However, 10 min of viewing a display that required constant ocular focus with changing vergence eye movements was sufficient to cause deficits of binocular vision.
Guidelines for Presenting Quantitative Data in HFES Publications
Authors: Gillan Douglas J. , Wickens Christopher D. , Hollands J. G. , Carswell C. Melody
Published: January 2007

This article provides guidelines for presenting quantitative data in papers for publication. The article begins with a reader-centered design philosophy that distills the maxim “know thy user” into three components: (a) know your users′ tasks, (b) know the operations supported by your displays, and (c) match user's operations to the ones supported by your display. Next, factors affecting the decision to present data in text, tables, or graphs are described: the amount of data, the readers′ informational needs, and the value of visualizing the data. The remainder of the article outlines the design decisions required once an author has selected graphs as the data presentation medium. Decisions about the type of graph depend on the readers′ experience and informational needs as well as characteristics of the independent (predictor) variables and the dependent (criterion) variable. Finally, specific guidelines for the design of graphs are presented. The guidelines were derived from empirical studies, analyses of graph readers′ tasks, and practice-based design guidelines. The guidelines focus on matching the specific sensory, perceptual, and cognitive operations required to read a graph to the operations that the graph supports.
Multiple perspectives on preparing teachers to teach reading
Authors: BARONE DIANE , MORRELL ERNEST
Published: January 2007

Book reviewed in this article:

Knowledge to Support the Teaching of Reading: Preparing Teachers for a Changing World. Catherine Snow, Peg Griffin, & M. Susan Burns. (Eds.). 2005.
Design of highly efficient cellulase mixtures for enzymatic hydrolysis of cellulose
Authors: Gusakov Alexander V. , Salanovich Tatyana N. , Antonov Alexey I. , Ustinov Boris B. , Okunev Oleg N. , Burlingame Richard , Emalfarb Mark , Baez Marco , Sinitsyn Arkady P.
Published: January 2007

An extremely highly active cellobiohydrolase (CBH IIb or Cel6B) was isolated from Chrysosporium lucknowense UV18‐25 culture filtrate. The CBH IIb demonstrated the highest ability for a deep degradation of crystalline cellulose amongst a few cellobiohydrolases tested, including C. lucknowense CBH Ia, Ib, IIa, and Trichoderma reesei CBH I and II. Using purified C. lucknowense enzymes (CBH Ia, Ib, and IIb; endoglucanases II and V; β‐glucosidase, xylanase II), artificial multienzyme mixtures were reconstituted, displaying an extremely high performance in a conversion of different cellulosic substrates (Avicel, cotton, pretreated Douglas fir wood) to glucose. These mixtures were much or notably more effective in hydrolysis of the cellulosic substrates than the crude multienzyme C. lucknowense preparation and other crude cellulase samples produced by T. reesei and Penicillium verruculosum. Highly active cellulases are a key factor in bioconversion of plant lignocellulosic biomass to ethanol as an alternative to fossil fuels. Biotechnol. Bioeng. 2007; 97: 1028–1038. © 2007 Wiley Periodicals, Inc.
Natural cellulose fibers from switchgrass with tensile properties similar to cotton and linen
Authors: Reddy Narendra , Yang Yiqi
Published: January 2007

We report the production and characteristics of natural cellulose fibers obtained from the leaves and stems of switchgrass. In this paper, the composition, structure and properties of fibers obtained from the leaves and stem of switchgrass have been studied in comparison to the common natural cellulose fibers, such as cotton, linen and kenaf. The leaves and stems of switchgrass have tensile properties intriguingly similar to that of linen and cotton, respectively. Fibers were obtained from the leaves and stems of switchgrass using a simple alkaline extraction and the structure and properties of the fibers were studied. Fibers obtained from switchgrass leaves have crystallinity of 51%, breaking tenacity of 5.5 g per denier (715 MPa) and breaking elongation of 2.2% whereas the corresponding values for fibers obtained from switchgrass stems are 46%, 2.7 g per denier and 6.8%, respectively. Switchgrass is a relatively easy to grow and high yield biomass crop that can be source to partially substitute the natural and synthetic fibers currently in use. We hope that this research will stimulate interests in using switchgrass as a novel fiber crop in addition to being promoted as a potential source for biofuels. Biotechnol. Bioeng. 2007; 97: 1021–1027. © 2007 Wiley Periodicals, Inc.
Dibutyl phthalate biodegradation by the white rot fungus, Polyporus brumalis
Authors: Lee Soo‐Min , Lee Jae‐Won , Koo Bon‐Wook , Kim Myung‐Kil , Choi Don‐Ha , Choi In‐Gyu
Published: January 2007

In this study, white rot fungus, Polyporus brumalis, was applied to degrade dibutyl phthalate (DBP), a major environmental pollutant. The degradation potential and resulting products were evaluated with HPLC and GC/MS. As DBP concentration increased to 250, 750, and 1,250 µM, the mycelial growth of P. brumalis was inhibited. However, growth was still observed in the 1,250 µM concentration. DBP was nearly eliminated from culture medium of P. brumalis within 12 days, with 50% of DBP adsorbed by the mycelium. Diethyl phthalate (DEP) and monobutyl phthalate (MBP) were detected as intermediate degradation products of DBP. In culture medium, the concentration of DEP was higher than that of MBP during the incubation period. After 12–15 days, the concentrations of both decreased rapidly in the culture medium. The primary final degradation product of DBP in culture medium was phthalic acid anhydride, as well as trace amounts of aromatic compounds, such as α‐hydroxyphenylacetic acid, benzyl alcohol, and O‐hydroxyphenylacetic acid. According to these results, the degradation of DBP in culture medium by the white rot fungus, P. brumalis, may be completed through two pathways—transesterification and de‐esterification—which successively combine into an intracellular degradation pathway. Biotechnol. Bioeng. 2007; 97: 1516–1522. © 2007 Wiley Periodicals, Inc.
Effect of Impurities on the Nucleation of ADP from Aqueous Solution
Authors: Nagalingam S. , Vasudevan S. , Ramasamy P.
Published: January 2007

The nucleation study has been made with the saturated solution of Ammonium dihydrogen orthophosphate over the temperature range 25–40 °C. In the absence of impurities, classical nucleation theory predicts rates reasonably well only at the expense of some adjustable parameters like surface energy term. This has been attributed to the difficulties associated with the application of equilibrium thermodynamics to a process of kinetic origin. The presence of soluble impurities reduces the solubility and hence decreases the induction period. In our present work the amount of soluble impurity added has influenced the induction period. Actvation energies and surface free energies were determined for ADP solution relative to the impurities.
Some Factors Influencing the Rate of Heterogeneous Nucleation of Strontium Sulphate
Authors: Söhnel O.
Published: January 2007

The effect of the agitation intensity on nucleation, agglomeration, ripening, and recrystallization of SrSO4 crystals prepared by batch precipitation of equimolar solutions of SrCl2 and Na2SO4 (0.01, 0.015, and 0.02 M) at 25 °C was investigated. The dependence of the SrSO4 crystals shape and number on the time of the suspension ageing was also studied.
Possible Inaccuracies Involved in the Crystal Population Balance Method and their Elimination
Authors: Nývlt J. , Žáček St.
Published: January 2007

The analysis of crystal size distribution using the method of population density balance is aggravated by two sources of possible errors: the uncertainty in calculating the population densities (numbers of crystals) from weight amounts of crystals and the necessity of extrapolating the population densities into the range of very small sizes in order to obtain the nuclei population density. Employment of cummulative weight distribution data overcomes both of these difficulties and serves results suitable for design purposes. The comparison of both methods is shown using experimental data on continuous potash alum precipitation.
Influence of Dislocations in KDP Crystals on Laser Damage Threshold
Authors: Endert H. , Melle W.
Published: January 2007

The dislocation density in KDP crystals has been determined by X‐ray diffraction topography (LANG method). A method for determining the laser damage thresholds in dependence on dislocation density is described. It is found that dislocations with a density about 103 cm−2 reduce the laser damage threshold up to a factor of two compared with perfect regions. It is shown that experimentally measured damage results can be explained theoretically.
Etching Studies on Potassium Dichromate (KBC) Crystals
Authors: Sangwal K. , Szurgot M.
Published: January 2007

An investigation of the revelation of dislocations in potassium dichromate (KBC) crystals by etching in water, alcohls, and in inorganic acids mixes with acetone and alcohols is carried out. It is observed that several solutions including water, alcohols and organic acids produce disslocation etch pits on various faces of KBC crystals. Observations of twining and dissolution anisotorpy of (001) faces are also presented. Etching of (001) cleavage faces of same crystals in an etchant composed from 1 part HNO3 and 3 parts acetone indicates the possible growth of another phase at low temperatures.
EBIC/TEM Studies on the Relation between Electrical Properties, Crystallographic Structure, and Interaction with Point Defects of Epitaxial Stacking Faults in Silicon
Authors: Kittler M. , Bugiel E.
Published: January 2007

Only after annealing, EBIC investigations on epitaxial layer defects partly gave contrasts. More information on the crystallographic structure of these defects was obtained in subsequent HVEM investigations. Experimental results confirmed the supposition that only the decoration of the crystallographic defects with additional recombination centres (impurity atoms), and not existence of the defects themselves, results in a detectable EBIC contrast. The observed getter efficiency of the various defect types is discussed. This efficiency is growing with increasing lattice distortion.
Double‐crystal Topographic Investigation of the Shape of Silicon Wafers after Oxidation
Authors: Zaumseil P.
Published: January 2007

The shape of silicon wafers plastically deformed by slip band production during an oxidation process is investigated with double‐crystal topography. In dependence on the Burgers vector of the slip band dislocations the tilt of parts of the wafer, especially between crossed slip bands, is observed and the wafer is curved in general. A local quantitative determination of the radius of curvature is possible.
Crystal Growth in Magnetic Fields (I) Crystallization of Me (NH4)2(SO4)2 · 6 H2O (Me = Zn, Cu, Ni, Fe) from Aqueous Solutions in Moderate Magnetic Fields
Authors: Kuschel F. , König AN , Gropp R.
Published: January 2007

There are several reports in the literature concerning the study of the influence of magnetic fields on nucleation and crystal growth. Because of the partially opposite findings, the question whether the application of magnetic fields especially for mass crystallization processes may be of advantage has not been cleared yet. Therefore, the displacement rates of [110] and [001] single crystal faces of four Tutton's salts Me(NH4)2(SO4)2 · 6 H2O (Me = Zn, Cu, Ni, Fe) from supersaturated aqueous solutions in a transversal direct magnetic field (B ≦ 1.4 T) has been measured and compared. Within the detection limit no reproducible effect was observed with Me = Zn, Cu, and Fe. A small growth acceleration occured in case of Ni(NH4)2(SO4)2 · 6 H2O. The results which will be completed by measurements at higher magnetic flux densities, support the viewpoint that the application of magnetic fields on crystallization of diamagnetic substances from solutions offers no real advantage.
Sintering as a result of defect structure
Authors: Schatt W. , Friedrich E.
Published: January 2007

Experimental results are presented and conceptions are developed for the qualitative understanding of the fast densification which is frequently observed in the shrinkage stage during the sintering of disperse one‐component compacts. They are based on a dislocation multiplication in the powder particle contact regions which is temporarily connected with the contact growth. Thus, a defect structure state is developed due to which it seems possible that the powder particles as a whole move into the pore space through alternating sliding and deformation processes and get densely packed.
Helical dislocations produced by low temperature thermocycling in a Ti–Al Alloy
Authors: Lavrentev F. F. , Pokhil YU. A. , Dudko P. P.
Published: January 2007

By transmission electron microscopy (TEM), the structural state of a Ti–Al alloy subjected to low temperature thermocycling from 300 to 77 K has been investigated. As the result of this observation, helical dislocations were revealed with the density 109 cm−3. These were generated mainly by grain boundaries or subboundaries. Their formation is thought to be associated with thermomechanical stresses arising during thermocycling. Thermomechanical stresses at the interface of neighbouring grains, estimated with making allowance for the anisotropy of the linear expansion coefficient, appeared to be about 7 kg/mm2. It is assumed that helical dislocation formation is one of the ways in which local internal stresses are relieved.
Dielectric behaviour of the smectic I phase
Authors: Kresse H. , Buka A.
Published: January 2007

The dielectric behaviour of 4‐n‐butyl‐4′‐n‐dodecyloxyazobenzene was investigated in the smectic A, C and I phases from 102 to 3 ṁ 106 Hz. In all phases a dielectric relaxation process could be found which is connected with the reorientation of the molecules around their short molecular axes. At the phase transition SC/SI a step of one decade was observed in the relaxation frequencies.