bluuebunny/crossref_metadata_2025 huggingface dataset:
Conceptualizing in Assembly Tasks
Authors: Baggett Patricia , Ehrenfeucht Andrzej
Published: July 2017

A method is presented to determine a person's hypothetical conceptualization of an object—its breakdown into subassemblies, sub-subassemblies, and so on—from the person's sequence of requests for pieces used in constructing it. Also, a technique is provided to determine whether, given a group of conceptualizations, there is a typical one. Results of the experiments showed that assembly instructions presenting a typical conceptualization yielded better structural and functional performance than did instructions presenting a minority conceptualization. Conceptualizations were derived from objects built from memory (and incorrectly) by people who first studied typical or minority instructions. A new distance measure was used to determine how far these conceptualizations were from those presented in the instructions. Typical instructions yielded typical conceptualizations; importantly, minority instructions also yielded typical conceptualizations, although they were significantly less typical than those from typical instructions. The results are discussed in terms of both their theoretical and methodological significance and their practical significance in the design of procedural instructions.
Reading Self-Paced Moving Text on a Computer Display
Authors: Chen Hsuan-Chih , Chan Kin-Tong , Tsoi Kam-Cheong
Published: July 2017

Readability of text moved horizontally along a single line on a computer display was studied as a function of two line lengths and three jump lengths. In the experiment text was advanced in continuous jumps of one or several characters at a time and the speed of text display was controlled in real time by subjects via a control knob. The results showed that jump lengths of five and nine character spaces resulted in a higher reading rate than the one-character jump condition. Furthermore, text appearing in 20-character windows was read as fast as text in 40-character windows. However, when text was advanced one character space at a time, the small window condition resulted in higher comprehension than the large window condition. Implications of these results for reading self-paced computer displays are discussed.
Improper Shoulder Belt Use by Maryland Drivers
Authors: Ciccone Michael A. , Wells Joann K.
Published: July 2017

This study was undertaken to determine the types and frequency of improper shoulder belt use–with particular emphasis on belt slack—in a state where belt use is mandatory. Motion picture films of drivers approaching stop signs in Maryland were analyzed by a trained panel to ascertain belt use and misuse. Over half the drivers of 1974–1987 model vehicles were observed to be belted. Slack in shoulder belts was the most common type of misuse and was much more prevalent among drivers of domestic cars than of imported cars. For belted drivers of domestic cars, 27% had 25–50 mm of slack in their belts, and 8% had 75 mm or more. By contrast, only 5% of belted drivers of imported cars had 25–50 mm of slack, and none had 75 mm or more. The window shade slack mechanism, found only in domestic vehicles, was most often associated with the slack.
An Exploratory Study of the Use of Movement-Correlated Cues in an Auditory Head-Up Display
Authors: Sorkin Robert D. , Wightman Frederic L. , Kistler Doris S. , Elvers Greg C.
Published: July 2017

An auditory head-up display (AHUD) can provide a pilot with information about target azimuth and elevation. The AHUD presents headphone stimuli whose apparent position is fixed relative to the cockpit and invariant with respect to head movement. In normal (movement-linked) operation the AHUD samples the head position and then corrects the headphone stimuli so that they are perceived to be at fixed positions in physical space. This experiment tested the ability of observers to localize targets with an AHUD under different movement conditions. After listening to a sequence of three signals, the observer had to indicate the target's location. Three different conditions relating the observer's head movement to the target's spatial position were tested: (a) target fixed in physical space (normal AHUD mode), (b) no head movement allowed, and (c) target fixed in position relative to the observer's head. Azimuthal localization was much better when the position of the stimulus was veridically correlated with head movement, demonstrating the contribution of visual, kinesthetic, and vestibular cues to sound localization.
Entry and Selection Methods for Specifying Dates
Authors: Gould John D. , Boies Stephen J. , Meluson Antonia , Rasamny Marwan , Vosburgh Ann Marie
Published: July 2017

Experienced and inexperienced computer users specified event dates using seven different human-computer interaction methods (three entry and four selection methods). Both groups were faster and more accurate when using the three entry methods than the four selection methods. The rank order of performance with these methods was about the same for both groups of participants. The number of keystrokes required by each method was a good predictor of participants' performance time. It was found that decomposing selection tasks into separate fields is advisable.
Perception of Risk in Automotive Systems
Authors: Macgregor Donald G. , Slovic Paul
Published: July 2017

Thirty subsystems constituting a functioning motor vehicle, including brake, steering, suspension, engine, electrical, and fuel systems, were evaluated by individuals on a set of risk characteristic scales. These included overall vehicle riskiness, manufacturer's anticipatory knowledge of system defects during vehicle design, likelihood of severe consequences in the event of system failure, controllability of the vehicle, and observability of impending failure. An analysis of the resulting judgments revealed two composite factors, one representing the controllability of consequences and the other representing observability. Both factors were highly related to judgments of risk, desire for risk regulation, and anticipated recall compliance. A comparison of risk judgments with accident data suggested that for some vehicle systems, particularly those serving a communication function in the driving task, drivers may underestimate the actual risk they face when system performance has degraded.
Effect of Prior Headlighting Experience on Ratings of Discomfort Glare
Authors: Sivak Michael , Olson Paul L. , Zeltner Kristine A.
Published: July 2017

This study investigated the effects of prior headlighting experience on ratings of discomfort glare from headlamps in an actual driving situation. Specifically, discomfort glare ratings given by West Germans who had recently arrived in the United States and were, presumably, used to the relatively low levels of glare associated with head lamps in West Germany were compared with ratings given by U.S.-born subjects. The West German subjects reported significantly more discomfort than did the U.S. subjects. This finding is in agreement with the so-called range effect, in which subjective judgments are affected by the range of available stimuli. Consequently, the present findings support the hypothesis that discomfort glare ratings are affected by prior visual experience.
Effects of Handle Angle and Work Orientation on Hammering: II. Muscle Fatigue and Subjective Ratings of Body Discomfort
Authors: Schoenmarklin Richard W. , Marras William S.
Published: July 2017

This research investigated how changes in hammer handle angle and hammering orientation affected muscle fatigue in the forearm and subjective ratings of body discomfort. Forearm muscle fatigue and discomfort ratings were not significantly affected by handle angle, but they were significantly higher in the wall hammering orientation than in the bench orientation. The research in this article and in the companion article (Part I) reveal that for novices, hammers with handles angled in the range of 20-40 deg are advantageous because (1) they reduce ulnar deviation and may possibly decrease the incidence of hand/wrist disorders, and (2) they do not significantly affect hammering performance in the bench conditions, forearm muscle fatigue, or subjective ratings of body discomfort.
Influence of Experience on Age Differences in Cognitive Functioning
Authors: Salthouse Timothy A.
Published: July 2017

To the extent that adult age differences in measures of cognitive performance have implications for functioning outside the psychological laboratory, the question of the role of experience as a potential moderator of these differences becomes extremely important. Three categories of research relevant to this issue are reviewed, and methodological limitations of each type of research are discussed. Although it is frequently asserted that experience minimizes cognitive differences associated with aging, the evidence currently available does not appear consistent with a strong experiential moderation of age-related effects in cognitive performance. However, the paucity of relevant studies and the methodological weaknesses of those that do exist preclude a definitive conclusion at the present time. Additional research with improved methodology is necessary before strong conclusions can be reached concerning effects of experience on age differences in cognition.
Self-Reported Visual Problems of Older Drivers
Authors: Kosnik William D. , Sekuler Robert , Kline Donald W.
Published: July 2017

We conducted a survey in order to gain insights into the reasons older persons decide to give up driving. Our survey focused on vision. We probed the relationship between visual deficiencies and driving status by asking older people about the problems they encountered while performing routine visual tasks. The results showed that older persons who had recently given up driving reported more visual problems than did their driving counterparts. These problems related to difficulties in dynamic vision, visual processing speed, visual search, light sensitivity, and near vision. The results suggested that older persons are sensitive to their own visual deficits and that this awareness influences decisions about driving.
Coefficient of Friction and Subjective Assessment of Slippery Work Surfaces
Authors: Swensen Eric E. , Purswell Jerry L. , Schlegel Robert E. , Stanevich Ronald L.
Published: July 2017

Research was conducted to determine how well subjects could distinguish between surfaces with different coefficient of friction (COF) values and to evaluate how well subjective ratings of slipperiness correlated with the actual COF values. Thirty-three ironworkers experienced in working and walking on steel surfaces and 23 university students inexperienced with these tasks participated in the study. Subjective slipperiness ratings for a variety of climbing and walking conditions were obtained from the subjects. It was found that subjects could identify differences in the slipperiness of four types of steel coatings tested in the study. There was a high correlation between the subjective ratings and the measured COF values. Subjects did not slip at a COF of 0.41 but did lose footing at a COF of 0.20.
Entry and Selection-Based Methods of Human-Computer Interaction
Authors: Greene Sharon L. , Gould John D. , Boies Stephen J. , Rasamny Marwan , Meluson Antonia
Published: July 2017

The merits of entry and selection interaction methods were compared using an airline flight reservation scenario with a relatively small data base. For both experienced and inexperienced users, the most effective method was entry combined with autocompletion (i.e., string completion). Users took the least amount of time to carry out tasks with this method and also preferred it over both entry without autocompletion and selection from either a one-item menu or an N-item menu. Entry with autocompletion was not affected by increases in the underlying data base size. Both the entry with autocompletion methods and the selection method were not affected by the spelling difficulty level involved in making a reservation, but the unaided entry methods were. The results are discussed in the context of the Interactive Transaction System (ITS) project, which is a user-interface management system that separates the content of the user interface from the style of the interface.
Masking in Three-Dimensional Auditory Displays
Authors: Doll Theodore J. , Hanna Thomas E. , Russotti Joseph S.
Published: July 2017

The extent to which simultaneous inputs in a three-dimensional (3D) auditory display mask one another was studied in a simulated sonar task. The minimum signal-to-noise ratio (SNR) required to detect an amplitude-modulated SOO-Hz tone in a background of broadband noise was measured using a loudspeaker array in a free field. Three aspects of the 3D array were varied: angular separation of the sources, degree of correlation of the background noises, and listener head movement. Masking was substantially reduced when the sources were uncorrelated. The SNR needed for detection decreased with source separation, and the rate of decrease was significantly greater with uncorrelated sources than with partially or fully correlated sources. Head movement had no effect on the SNR required for detection. Implications for the design and application of 3D auditory displays are discussed.
A Dyadic Protocol for Training Complex Skills
Authors: Shebilskem Wayne L. , Regian J. Wesley , Arthur Winfred , Jordan Jeffrey A.
Published: July 2017

We tested a dyadic training protocol derived from cognitive and social theories of complex skill acquisition. Forty undergraduates practiced Space Fortress, a video game-like research tool, for 10 sessions of eight practice and two test games. Half of them practiced and tested alone; the others had identical tests but dyadic practice, in which they controlled part of each practice while being interlocked with a partner who controlled the rest. Subjects practiced both parts and their connections by alternating roles and by modeling their partners. Trainer time and resources were half for the dyadic group, and performance was equivalent. We discuss applied and basic implications of this 100% increase in training efficiency.
Using the Stereokinetic Effect to Convey Depth: Computationally Efficient Depth-from-Motion Displays
Authors: Kaiser Mary K. , Proffitt Dennis R.
Published: July 2017

Recent developments in microelectronics have encouraged the use of 3D data bases to create compelling volumetric renderings of graphical objects. However, even with the computational capabilities of current-generation graphical systems, real-time displays of such objects are difficult, particularly when dynamic spatial transformations are involved. In this paper we discuss a type of visual stimulus (the stereokinetic effect display) that is computationally far less complex than a true three-dimensional transformation but yields an equally compelling depth impression, often perceptually in discriminable from the true spatial transformation. Several possible applications for this technique are discussed (e.g., animating contour maps and air traffic control displays so as to evoke accurate depth percepts).
Redundant Use of Luminance and Flashing with Shape and Color as Highlighting Codes in Symbolic Displays
Authors: van Orden Karl F. , Divita Joseph , Shim Matthew J.
Published: July 2017

Three visual search experiments evaluated the benefits and distracting effects of using luminance and flashing to highlight subclasses of symbols coded by shape and color. Each of three general shape/color classes (circular/blue, diamond/red, square/yellow) was divided into three subclasses by presenting the upper half, lower half, or entire symbol. Increasing the luminance of a subclass by a factor of two did not result in a significant improvement in search performance. Flashing a subclass at a rate of 3 Hz resulted in a significantly shorter mean search time (48% improvement). Increasing the luminance of one subclass (by a factor of five) while simultaneously flashing another significantly improved search times by 31% and 43% respectively, compared with nonhighlighted search conditions. In each experiment, the search times for nonhighlighted target subclasses were not affected by the presence of brighter and flashing targets. The failure of the initial experiment to find a significant performance improvement caused by increasing symbol luminance suggested that a larger luminance increase was necessary for this code to be effective. The overall results suggest that using luminance and flashing to highlight subclasses of color-and shape-coded symbols can reduce search times for these subclasses without producing a distraction effect by way of a concomitant increase in the search times for unhighlighted symbols.
Operation of Controls on Consumer Products by Physically Impaired Users
Authors: Kanis H.
Published: July 2017

The self-reliance of the physically impaired can be seriously jeopardized by their inability to operate everyday products, especially if both upper extremities are impaired. To determine the difficulties impaired users encounter in operating consumer product controls, on-site video recordings were made of subjects suffering from arthritis or a muscular disease. Subjects' force exertion was compared with that of a group of nonimpaired users. The resulting inventory allowed the analysis of the manipulation problems faced by impaired subjects and the development of design recommendations. In this study the force exerted by the subjects and that required to operate the controls were measured. A comparison of the results of these force measurements led to a number of conclusions. This study led to the following design recommendations: the amount of force required to operate controls should be kept as low as possible; the user should not be required to make two manipulations at the same time. such as simultaneously pushing and rotating a control device; pushing is preferable to rotating; and there should be a great degree of freedom to manipulate controls.
Cockpit Checklists: Concepts, Design, and Use
Authors: Degani Asaf , Wiener Earl L.
Published: July 2017

Although the aircraft checklist has long been regarded as a foundation of pilot standardization and cockpit safety, it has escaped the scrutiny of the human factors profession. The improper use, or nonuse, of the normal checklist by flight crews is often cited as a major contributing factor to aircraft accidents. This paper reports the results of a field study of flight deck checklists and examines this seemingly mundane yet critical device from several perspectives: its functions, format, design, length, and usage, and the limitations of the humans who must interact with it. Certain sociotechnical factors, such as the airline "culture," cockpit resource management, and production pressures that influence the design and use of this device, are also discussed. Finally, a list of design guidelines for normal checklists is provided. Although the focus of this paper is on the air transport industry, most of the principles discussed apply equally well to other high-risk industries, such as maritime transportation, power production, weapons systems, space flight, and medical care.
A Memorandum
Authors: LePan D. V.
Published: July 2017

Not all the messages to the Department of External Affairs in Ottawa from its officers abroad deal with issues of foreign policy or with matters under negotiation between the Canadian and other Governments. Sometimes they are more impressionistic. What follows is a memorandum prepared in October 1947 by Mr D V LePan when he was a First Secretary on the staff of the Canadian High Commissioner in London after a trip to the Continent with the Hon. D. C Abbott, who was at that time Canadian Minister of Finance. The memorandum has been released for publication by the Department of External Affairs with only a few excisions.
The Lockerbie Case Law
Authors: Shiels Robert
Published: July 2017

The destruction of an aircraft while it was in flight over Lockerbie in Scotland in 1988 led to a criminal trial 12 years later. That trial took place in The Netherlands within a specially constituted court where the law applied was that of Scotland. This article describes and considers the nine reported cases that have so far resulted from the arrest and prosecution of those accused of the Lockerbie bombing.
Provocation: The Ongoing Subservience of Principle to Tradition
Authors: Neal Luke , Bagaric Mirko
Published: July 2017

The defence of provocation has been highly criticised. Most commentators argue that the defence is misguided. There does not appear to be any community pressure to preserve the defence. Despite this, legislatures are reluctant to abolish provocation as a partial defence to murder. This article examines the underlying rationale for the defence. It concludes that the defence is founded on a flawed assumption about human nature—that people are captive to some of their emotional states. It is also argued that the convoluted and confusing (if not confused) test for provocation is evidence of the unsound nature of the defence—it is simply a case of not being able to develop a feasible (and candid) principle for a doctrine that is devoid of a sound justification.
Reinnervation of Teeth Following Segmental Osteotomy in the Cat
Authors: Robinson P. P.
Published: July 2017

Reinnervation of teeth following osteotomy has been investigated in cats using electrophysiological techniques. Theingrowing nerve fibers were derived from the regenerating ipsilateral inferior alveolar nerve, the ipsilateral mental and lingual nerves, and the contralateral lingual nerve. The regenerating fibers conducted more slowly and were fewer than normal.
Local Immunity to Bacteroides gingivalis in Periodontal Disease
Authors: Kagan Jonathan M.
Published: July 2017

The histopathologic status of gingival tissue was assessed according to the criteria of Page and Schroeder. Rhodamine-labeled bacteria were used to assess the antigenic specificity of plasma cells in the tissue. Examination of tissue sections revealed that 31.6% of plasma cells in the advanced lesions bound the labeled bacterium, compared with only 3.1% of the cells in the early lesions. These results indicate that local immunity to Bacteroides gingivalis is greater in the more advanced than in the earlier forms of periodontal disease.
Use of Human Minor Salivary Glands in Basic and Applied Secretion Research
Authors: Izutsu K.T. , Schubert M.M. , Truelove E.L. , Johnson D.E.
Published: July 2017

Previous findings from studies utilizing human labial and palatine minor salivary glands are reviewed. These studies took histopathological, biochemical, and ultrastructural approaches, and focused on control and diseased glands. Disease-oriented summarizations are used, and control results are discussed in the context of disease-related findings. Findings are reviewed separately for electrolytes, macromolecules, and ultrastructure. In control subjects, minor gland salivary electrolyte concentrations are dependent on flow rate, and this dependence may be altered by diseases such as cystic fibrosis as-well as by inflammatory situations such as graft-versus-host disease. There is also evidence that salivary electrolyte secretion processes are not similar in labial and palatine minor glands. Studies of salivary macromolecular composition are reviewed for control subjects and for patients with graft-versus-host disease and Sjögren's syndrome. The findings indicate that the macromolecular contents of labial and palatine gland saliva are similar, but that both are significantly different from that for major gland saliva. Finally, studies attempting to measure disease-related changes in intracellular composition are reviewed. It is concluded that the minor salivary glands are important models for the study of exocrine gland physiology and pathophysiology in man.
The Rheology of Saliva
Authors: Schwarz W. H.
Published: July 2017

The rheology of saliva affects the coating and lubrication of oral surfaces and the consistency of ingested foods. Salivary gland dysfunction can cause tissue damage and dysphagia. Therefore, we have considered the problem of designing a synthetic saliva for medical management. Also, we have measured certain rheological properties [shear-dependent viscosity η (k)] and the frequency-dependent moduli [G′(f) and η′(f)] of normal stimulated whole saliva. Analysis of the rheological data and consideration of requirements for using artificial saliva have resulted in a better understanding of the rheological functions of natural saliva and the desirable characteristics of synthetic saliva. In addition, we have measured rheological properties of two commercial saliva substitutes for comparison.
Immunologic Approaches to the Therapy of Auto-Immune Salivary Gland Disease
Authors: Lane H.C. , Fauci A.S.
Published: July 2017

A variety of immunologic mechanisms may theoretically give rise to disease in the salivary glands. Among them are abnormal antibody production, hyper-reactive T-lymphocytes, and mono- or oligoclonal expansions of B-lymphocytes, While it is not clear which, if any, of these mechanisms are of prime importance in the immunopathology of salivary gland disease, they provide a framework, within which to discuss theoretical approaches to the treatment of auto-immune salivary gland disease. Among the techniques used to decrease antibody-induced damage are non-steroidal anti-inflammatory agents, plasmapheresis, and corticosteroids. Cyclosporin, monoclonal antibodies, and biologic response-modifiers may be used to modulate T-cell function, and anti-idiotype antibodies or immunosuppressive agents may be used to treat malignant expansions of B-cells. Although the generally benign nature of auto-immune salivary gland disease precludes the use of many of the potentially toxic treatment regimens discussed here, the appreciation of these approaches to immunomodulation provides a basis upon which to develop new and innovative therapeutic strategies.
Correlation between the BANA Test and Oral Malodor Parameters
Authors: Kozlovsky A. , Gordon D. , Gelernter I. , Loesche WJ , Rosenberg M.
Published: July 2017

The purpose of the present investigation was to test the association between the BANA test (Perioscan®, Oral-B), and oral malodor parameters. The subject population consisted of 52 Israeli adults, 43 of whom complained of oral malodor. Oral malodor measurements consisted of peak and steady-state volatile sulphide measurement by a portable sulphide monitor (Interscan Corp., model 1170), as well as organoleptic measurements of malodor from whole mouth, tongue, and saliva. Samples for the BANA test were obtained from four loci (shallow pocket, deep pocket, tongue dorsum, saliva); results were scored as negative (0), weak (1), or strong (2). BANA scores were significantly associated with odor-judge ratings, with the highest association obtained when BANA saliva scores and odor-judge saliva assessment were compared (r = 0.500; p < 0.001). BANA tests from the different loci were not significantly associated with sulphide monitor levels. Stepwise multiple-regression analysis of odor-judge measurements in terms of sulphide levels and average BANA scores showed that both log peak sulphide levels as well as BANA scores were significantly factored into the equations, yielding, in all cases, highly significant correlations (multiple r = 0.57, 0.50, and 0.59, respectively, with significance levels of 0.0001, 0.001, and < 0.0001, for whole mouth, tongue, and saliva malodor, respectively). The results suggest that the BANA scores are associated with a component of oral malodor which is independent of volatile sulphide measurements and suggest its use as an adjunct test to volatile sulphide measurement.
SEM Evaluation of the Resin-Dentin Interface with Proprietary Bonding Agents in Human Subjects
Authors: Walshaw P.R. , McComb D.
Published: July 2017

Laboratory studies on dentin bonding do not replicate physiological reality. This study examined with SEM the attachment produced in vivo under clinical conditions. Forty-four cavities were prepared in buccal/ lingual surf aces of 16 premolar teeth scheduled for extraction and assigned randomly for treatment with: All-Bond 2 (Bisco) (A) with and (B) without dentin etch, (C) Scotchbond 2 (3M), (D) Scotchbond Multi-Purpose (3M), and (E) controls, using Enamel Bond (Kulzer) with dentin etch. After atraumatic extraction, restorations were split transversely by freeze-fracture and acid-treated. SEM examination of A revealed significant areas of gap-f ree attachment, with evidence of an acid-resistant hybrid layer (5-8 μm), often with resin tags of various lengths. Resin-reinforced collagen fibers were seen. Gap formation was coincident with lack of bonding resin layer over primed dentin. Attachment with B was less effective; a hybrid layer was infrequently seen and few resin tags. Pooled bonding resin at internal line angles appeared to favor an effective bond. Treatment C resulted in large areas of detachment, leaving an adherent primed dentin layer with short resin tags. Treatment D revealed significant areas of gap-f ree attachment and evidence of a hybrid layer. Controls (E) showed total bond failure. Attachment with A and D was secure, restorations remaining in situ even after freeze-fracture. This study confirmed that brief acid pre-treatment of dentin, allowing diffusion of resin-dentin primers, appeared conducive to development of an effective bond i n vi vo, similar to that reported in vitro.
The Reliability of Clinical Methods for Recording Temporomandibular Joint Sounds
Authors: Wabeke K.B. , Spruijt R.J. , van der Zaag J.
Published: July 2017

Measurement errors in recording temporomandibular joint sounds may originate from variation between observers and from variation in the phenomenon. Laboratory settings enable various procedures to be used to minimize both sources of variation. These procedures yield some excellent intra- and inter-examiner reliabilities, but this does not imply that dentists in a clinical setting are likely to evaluate temporomandibular joint sounds in a comparable way. This study was designed to evaluate clinical joint sound assessment methods (palpation and stethoscopy) without using special precautions to minimize variance. An attempt was made to quantify the signal variance. Within- and between-examiners agreement is estimated for both methods in a sample of 44 non-patients. The results show that two clinically experienced craniomandibular disorders specialists were able to reach fair to good agreement on the identification of (the number of) temporomandibular joint sounds. There was some disagreement with respect to the number of reciprocal clicks. Compared with the palpation technique, stethoscopy is more sensitive, especially with regard to crepitation. Based on the electronically recorded sounds, both examiners appeared to be overconsistent. It is concluded that the use of both palpation and stethoscopy in clinical settings can be justified but that both methods have limitations. When, in a given clinical setting, these limitations are acceptable, there appears to be no need for extra-sensitive but expensive electronic recording devices.
Tensile Properties of Mineralized and Demineralized Human and Bovine Dentin
Authors: Sano H. , Ciucchi B. , Matthews W.G. , Pashley D.H.
Published: July 2017

The relative contribution of the matrix of dentin to the physical properties of dentin is unknown but thought to be small. The objective of this study was to test the hypothesis that the demineralized matrix of dentin contributes little to the strength of dentin by measuring and comparing the ultimate tensile strength and modulus of elasticity of mineralized and demineralized dentin. Small slabs (4 x 0.5 x 0.5 mm) of bovine and human dentin were tested in a microtensile testing device in vitro. Human coronal mineralized dentin gave a mean ultimate tensile strength (UTS) of 104 MPa. Bovine incisor coronal dentin exhibited a UTS of 91 MPa, and bovine root dentin failed at 129 MPa. The modulus of elasticity of mineralized bovine and human dentin varied from 13 to 15 MPa. When dentin specimens were demineralized in EDTA, the UTS and modulus of elasticity fell to 26-32 MPa and 0.25 GPa, respectively, depending on dentin species. The results indicate that collagen contributes about 30% of the UTS of mineralized dentin, which is higher than was expected.
Isothermal Anneal Effect on Microcrack Density around Leucite Particles in Dental Porcelain
Authors: Mackert J.R. , Rueggeberg EA , Lockwood P.E. , Evans A.L. , Thompson W.O.
Published: July 2017

Because of the large differential in thermal expansion coefficient between leucite and the surrounding glass matrix, microcracks form around the leucite crystallites during the manufacture of dental porcelain frits. These microcracks decouple leucite from the surrounding glass matrix and affect the bulk thermal expansion of the porcelain frit (Binns, 1983). The purpose of this study was to determine if the microcrack density in a dental porcelain decreased as a result of isothermal heat treatment. Ten specimens of a commercial dental porcelain that had previously exhibited an increase in thermal expansion as a function of isothermal heat treatment were prepared and divided into two groups. The experimental group was heated to 750°C and held for 16 minutes at that temperature. The control group received no anneal. The mean microcrack densities were determined by quantitative stereology to be 575 cm2/cm 3 ± 75 cm2/cm3 (mean ± SEM) for the control group (no anneal) and 231 cm2/cm3 ± 25 cm2/cm3 for the experimental group (16-minute anneal at 750'C). The specimens annealed at 750°C had a significantly lower microcrack density (p < 0.001) than those that received no anneal. A model was developed to estimate the effect of microcracking on thermal expansion of the porcelain, and a 6% increase in the coefficient of thermal expansion of the porcelain was predicted from this model as a result of this decrease in microcrack density.
Matrix Metalloproteinases (MMP-2 and MMP-9) of the Oral Cavity: Cellular Origin and Relationship to Periodontal Status
Authors: Makela M. , Salo T. , Uitto V.-J. , Larjava H.
Published: July 2017

Proteolytic enzymes released by the host cells are associated with the tissue destruction in periodontal diseases. Matrix metalloproteinases (MMPs) have the primary role in this process, since, in concert, they can degrade most of the extracellular matrix components. In the present study, we investigated MMP-2 and MMP-9 in oral fluids of healthy subjects and periodontitis patients and the contributions of different oral cells to the enzyme production. The enzymograms revealed that the main gelatinase in oral rinses, crevicular fluid, and whole saliva migrated at 92 kDa. Activity was also detected at 200 kDa and 130 kDa and minor activity at 86 kDa, 72 kDa, and 40 kDa. Traces of gelatinolytic activity were also detected in pure parotid secretions. The 92-kDa enzyme was identified to MMP-9 and the 200-kDa gelatinase to MMP-2, by means of specific anti-72-kDa antiserum. Gingival keratinocytes produced mainly MMP-9, while gingival and granulation tissue fibroblasts expressed MMP-2. Glandular tissue contained mainly MMP-9, and mRNA for MMP-9 was also found in acinar epithelial cells. Periodontitis patients had significantly higher levels of MMP-9 than healthy subjects. Also, MMP-2 was elevated in periodontitis patients. Periodontal treatment reduced the amount of gelatinases dramatically. This study shows that gelatinases are produced by various cells in the oral cavity. The amount of gelatinases is elevated during periodontal disease, while conventional periodontal treatment efficiently reduces the levels these enzymes. We suggest that MMP-2 and MMP-9 could participate in tissue destruction in periodontitis.
Incorporation of Bacterial Inhibitor into Resin Composite
Authors: Imazato S. , Torii M. , Tsuchitani Y. , McCabe J.F. , Russell R.R.B.
Published: July 2017

Attempts to produce resin composite with antibacterial properties by incorporation of an antibacterial agent such as chlorhexidine have been reported, but problems can arise due to release of the inhibitory agent from the composite. Such problems may include toxic effects, influence on mechanical properties, and loss of effectiveness. A new monomer, methacryloyloxydodecylpyridinium bromide (MDPB), was synthesized by combining an antibacterial agent and methacryloyl group. The monomer was incorporated into resin composite to develop a non-releasing antibacterial composite. The ability of composite incorporating MDPB to inhibit growth and plaque accumulation by Streptococcus mutans in vitro was assayed, elution of antibacterial components from the material was investigated, and the influence of incorporation of MDPB on the mechanical properties of composite was studied. Uncured MDPB revealed antibacterial activity against S. mutans and six other species of oral streptococci, with the minimum inhibitory concentration for S. mutans being comparable with that of triclosan. After composite incorporating MDPB was cured, no elution of the antibacterial components was observed from the material, even after 90 days' immersion in water or other solvents. Growth of S. mutans on agar under specimens of MDPBcontaining composite was inhibited compared with controls. In a bacterial accumulation study, S. mutans accumulated to a lesser degree on the surface of composite incorporating MDPB (p < 0.05) than on control. Incorporation of MDPB had no significant influence on the mechanical properties of the composite.
Effect of Grinding and Fluoride-gel Exposure on Strength of Ion-exchanged Porcelain
Authors: Anusavice K.J. , Hojjatie B. , Chang T.-C.
Published: July 2017

Strengthening of dental porcelain through a diffusion heat treatment at 450°C of a potassium-enriched, ion-exchange surface coating has been demonstrated in several recent studies. However, little attention has been focused on the potential strength reduction of these materials when the treated surfaces are ground or etched under clinically simulated conditions. The objective of this study was to test the hypothesis that partial removal of the surface layers of ion-exchanged porcelains by grinding or exposure to acidulated fluoride gel will significantly reduce their flexure strength. Nine groups of body porcelain disks were ion-exchanged at 450'C for 30 min. One of these groups was subjected to ion exchange and no further surface treatment. Eight specimen groups were subjected to the following procedures after ion exchange: grinding to depths of 50 μm, 100 μm, 150 μm, 200 μm, and 250 μm, and exposure to acidulated fluoride for 30 min, 60 min, and 300 min. A tenth group (FC) was fired at 960°C and fast-cooled in air, but the disks were not subjected to the ion-exchange treatment. Surface stress was calculated from measured values of cracks induced in the treated surfaces. Fluoride exposure for up to 60 min resulted in a significant decrease in surface compression (P ≤ 0.05), although this treatment had no effect on strength. Grinding to a depth of from 100 μm to 250 μm caused a significant decrease in strength, while removal of a 50-μm layer caused no significant change (P > 0.05).
The Effects of Ion Sputtering on Dentin and its Relation to Depth Profiling
Authors: Miller R.G. , Bowles C.Q. , Gutshall P.L. , Eick J.D.
Published: July 2017

Characterization of the dentin surface and the dentin/adhesive interface is fundamental to investigations concerning adhesive bonding to dentin. It has been shown that good adhesive bonding depends on both the structure and composition of the dentin surface. A combination of ion sputter etching and Auger electron spectroscopy can be used to obtain surface composition and elemental depth profiles at interfaces. This investigation was conducted to examine the changes induced in human dentin by ion sputtering under conditions commonly encountered during depth profiling. The sputtering was conducted with argon ions at 7.5 keV and an ion flux ranging from 1018-1019 ions/m 2s. The amount of material sputtered was calculated from profilometer measurements of the sample surface. The surface composition was monitored by Auger electron spectroscopy. The results indicate that, under these conditions, collagen was removed at a much faster rate than hydroxyapatite, causing the surface composition of dentin to change during the sputtering process. The sputter yields for hydroxyapatite and collagen were found to be 5 and 28 atoms/ion, respectively, at a sputter angle of 45°. At a sputter angle of 29°, the yields were 2 and 25 atoms/ion, respectively. Both the changes in composition of dentin and the measured sputter rates are in agreement with the behavior predicted by a theoretical model for two phase materials (Blaise, 1978; Blaise et al., 1978).
Theology and the researching professional
Authors: Bennett Zoë
Published: July 2017

This article seeks to give a brief account and evaluation of an innovative collaborative project in theological eduation in the UK — the Professional Doctorate in Practical Theology (DPT), on which there are currently some fifty students in three universities (Anglia Ruskin with the Cambridge Theological Federation, Birmingham and Manchester. The University of Wales Lampeter has validated but currently not recruited). After a brief introduction describing the project, now in its third year, the article addresses three questions — why this work is ‘theological’, what we have learned in doing it about the appropriate supervision of candidates, and how such professional research can be subversive.
Do you understand what you are reading?
Authors: Moltmann Jürgen
Published: July 2017

The paper published here is the full text of the Charles Moule Lecture given at Ridley Hall, Cambridge on 10 June 2009. In the spirit of entering into a colloquium with the theological legacy of C. F. D. Moule, the paper asks the question: 'What do New Testament scholars have to say to the theologians, and what do theologians have to say to the New Testament scholars when they read the Scriptures together?' It concludes that, though in the past century New Testament scholars and theologians have sometimes allowed themselves to be pushed apart, it is both possible and important that they work together to understand what the Bible is saying today.
The wrong conclusion
Authors: Oakeshott Philip
Published: July 2017

Four points are made, with examples, challenging the literary arguments in favour of Mark 16.8 being the Gospel’s intended ending. First, the passage is full of unexplained loose ends such as ancient authors were careful to explain. Then, it lacks the closure given to ancient narrative of every genre. Third, Kelber’s ‘parabolic style’ does not fit: parables do often close abruptly, but not ambiguously, and always with a strong final line. Last, the early Church never from the first accepted 16.8 as the ending; Matthew and Luke not only tidy Mark’s loose ends but finish the narrative properly.
Being called out
Authors: Green Brutus
Published: July 2017

This paper seeks to criticize the model of ministerial training as formation, which continues to be defended in certain parts of the Church of England. Against the ideology of clericalism and submission that undergirds priestly ontology, and the damaging consequences of its impact upon training, Anglicanism has at its disposal resources for a far richer account of priesthood through the language of vocation and relation. It is the argument of this paper that such an understanding possesses far more scope for transforming priests and transforming priesthood.
What Sort of a God is to be Found in dementia?
Authors: Kevern Peter
Published: July 2017

Although a great deal has been written on pastoral responses to dementia, some of the theological questions it raises remain relatively unexplored. In this paper, the author argues that the widespread experience of living with someone with dementia has the potential to reshape our understanding of God's relation to humanity. He goes on to survey some key contributions to the existing theological literature on this subject and so to suggest directions for further theological work.
Is your resurrection too small?
Authors: Hovey Craig
Published: July 2017

This article asks about the kind of knowledge appropriate to Christ's resurrection and attempts to preserve its mystery against modern habits of knowing. Such habits inscribe a distance from the resurrection as event, tempting theology to enlist the resurrection in a larger set of arguments and proofs of something else like the reliability of Scripture's witness. As such, they diminish more generally all witness to contingent history. In contrast, this article finds a resource in Thomas Aquinas' claim that the resurrection is ‘fitting’, a judgement that Christians can only claim after the fact and perform in the work of worship and liturgy.
Revelation freshly erupting?
Authors: Shanks Andrew
Published: July 2017

Can modern poetry be said to have a ‘revelatory’ quality, in theological terms? Arguably the strongest candidate for such an accolade is the work of Nelly Sachs. Here is ‘poetry after Auschwitz’, by a Holocaust escapee, of unique religious intensity. Sachs was awarded the Nobel Prize for her poetry in 1966. And yet her work remains almost completely unknown in the English-speaking world, a state of affairs that surely needs remedying.
Unity in reconciled diversity
Authors: Carter David
Published: July 2017

This essay traces the development of the ecumenical concept of unity in reconciled diversity from its origins in the 1970s. It looks at ways in which it has subsequently been interpreted, received and critiqued. It makes suggestions as to how the concept might be further refined and tightened up in order to meet such criticism and lead to growth in authentic unity.
Addressing uncertainties about the effects of treatments offered to NHS patients: whose responsibility?
Authors: Chalmers Iain
Published: July 2017

‘You must work with colleagues and patients to maintain and improve the quality of your work and promote patient safety. In particular you must … help to resolve uncertainties about the effects of treatments.’

General Medical Council 1
Age-related macular degeneration: what do patients find on the internet?
Authors: Rennie Christina A , Hannan Shabeeba , Maycock Nick , Kang Chee
Published: July 2017

Objective

To assess the quality of information and readability of the top internet sites for age-related macular degeneration (AMD).

Design

An examination of the technical information provision, quality and readability of websites found during an internet search for ‘age-related macular degeneration’.

Setting

Six internet search engines were used to find 26 unique sites on AMD.

Main outcome measures

Technical information and quality were assessed using a simple grading system. Readability was assessed using a Simple Measure Of Gobbledygook (SMOG) rating.

Results

Twelve organizational, seven academic and seven commercial sites were identified. The average technical scores were 82.3%, 67.9% and 65.2% for each type of site, respectively ( P=0.097, one way ANOVA). The average quality scores were 62.2%, 62.6%, and 49.5% for each type of site, respectively ( P=0.356, one-way ANOVA). The average SMOG ratings were 16.3, 16.1, and 16.2 for each type of site, respectively ( P=0.983, one-way ANOVA). Fifteen of the sites provided details of new and emerging treatments, with seven providing a detailed discussion.

Conclusions

Many websites are now meeting the challenge of providing comprehensive information about AMD and its new treatments. Quality scores were disappointing, with sites needing to provide more evidence of authorship and attribution of information. The majority of sites had SMOG scores above 10, making them difficult for the average person to understand. As physicians we need to help design and direct patients to sites that provide high quality, current information.