The representation of space in mental models derived from text.

Mental models of text are representations of what the text is about (i.e., situations), rather than representations of the text itself. Many mental model theories propose that mental models, like real situations, are played out in a medium analogous to a Euclidean space so that distance has functional consequences. For example, when one mentally manipulates one element of the representation, one will notice other elements that are spatially close to it, and this will enhance their short-term accessibility. In a test of this noticing hypothesis, participants read texts that described the object-by-object construction of a spatial layout. According to the text, a critical object ended up close to a target object (in the spatial layout) or far from the target object. In neither case, however, was the relation between the critical object and the target object explicitly described in the text. The noticing hypothesis predicts that the accessibility of the target object will be enhanced when the critical object is close to it. We tested this prediction in seven experiments in which we also manipulated the number of objects described, whether the description was accompanied by a diagram, the presentation modality of the description, the number of dimensions in the spatial layout, and the measurement of accessibility. We failed to find consistent support for the noticing hypothesis. The data compel the conclusions that (1) spatial representations can be formed when one is reading, (2) these representations do not support automatic noticing of implicit spatial relations, (3) it is likely that the spatial representation is more topological or functional than Euclidean.

Fetal bradycardia resulting from maternal hypoglycemia. A report of two cases.

Two term-pregnant women presented in the obstetric unit with marked diaphoresis and tremulousness. Fetal heart rate monitoring revealed severe bradycardia. Both mothers had blood glucose levels consistent with the diagnosis of hypoglycemia. In both cases the fetal heart rate normalized with improvement in the mothers' glycemic state. The presence of maternal hypoglycemia should always be considered as a potential cause of fetal bradycardia.

You can treat the chemotherapy patient.

Increased numbers of cancer patients are treated with chemotherapy. Patients who receive antineoplastic agents can be at serious risk from dental infections and should be provided appropriate dental care. In many instances, indicated treatment can be accomplished by the patient's private dentist. Certain precautions, however, are necessary when treating dental patients medically compromised by chemotherapy. Dental conditions which may increase morbidity are identified and treatment recommendations are made. Guidelines for dental intervention before, during, and after chemotherapy are discussed with emphasis on the hematologic parameters necessary for safe dental care. The cyclic relationship between chemotherapy and oral complications is also reviewed.

Dental implants and chemotherapy complications.

The cancer patient receiving chemotherapy often suffers severe oral complications related to the administration of antineoplastic drugs. Cancer patients who also have transmucosal or endosseous dental implants pose special problems for medical oncologists and dentists, both when planning for chemotherapy and when providing supportive care during the course of treatment. The relationship between dental implants and cancer chemotherapy is described and complications experienced by implant patients treated with chemotherapy at The University of Texas M.D. Anderson Cancer Center are reviewed. Recommendations on various aspects of management involving implant evaluation and the removal or retention of dental implants are discussed.

Seal integrity of hollow-bulb obturators.

Five techniques using various materials were evaluated for their ability to produce a watertight seal between obturator and lid. Leakage was determined by an increase in sample weight above that attributed to sorption and by visualization of water inside the clear acrylic resin samples. A watertight seal was obtained for some samples in each of the test groups. Only the two-flask technique sealed with heat-processed acrylic resin produced a watertight seal in all samples. It was determined that pressure up to 30 psi for 1 hour does not rupture a sealed hollow bulb and immersion under pressure is required to detect leakage of a bulb in a short period of time.

The labial plate major connector in the partial mandibulectomy patient.

The indications, design, and advantages of the labial plate major connector as compared with the labial and lingual bar major connector are reviewed. The mechanical principles of increased rigidity and strength are discussed. The article suggests that the labial plate major connector may have an advantage over the labial bar major connector and should be considered when a labial connector is indicated.

Backscatter radiation at bone-titanium interface from high-energy X and gamma rays.

Occasionally head and neck cancer patients treated with high-energy X rays and gamma rays have titanium metal dental implants in their maxillae or mandibles. The resulting effect of the bone-metal interface on the radiation dose is of interest. Ionization measurements for 60Co gamma rays and 6 MV and 25 MV X rays were made. A thin-window parallel-plate chamber was used to determine the magnitude of the dose enhancement that was due to the backscattered electrons from titanium. The results showed that for 60Co there is a 15% increase in dose to solid bone at the entrance side of the titanium. For higher energy X rays, the increase in dose was about the same or slightly lower than for 60Co. Monte Carlo calculations substantiated the measurements. This increase in dose fell off rapidly and became negligible at 1-2 mm from the interface. This backscattered dose should be taken into account when planning radiation therapy treatment for patients with dental implants.

Cranial implant modification.

This technique combines the heat-cured resin system with an autopolymerizing resin system (Cranioplast). Cranioplast has been used since the early 1950s. Clinical trials have shown that it evoked the least severe inflammatory response when compared with other autopolymerizing methyl methacrylate systems. The advantage inherent in this technique is the ability to go to the operating room with a prefabricated heat-cured acrylic resin prosthesis and alter the implant with Cranioplast for excellent adaptation to the defect. The technique provides a well-fitting cranial implant prosthesis with good cosmetic results.

Claspless chrome-cobalt transitional removable partial dentures.

Many of the acrylic resin and bent-wire temporary partial dentures in use today produce pathologic changes in the oral mucosa. A method is outlined for the use of chrome-cobalt, instead of acrylic resin, to produce temporary prostheses. The resulting temporary partial dentures are esthetically pleasing and biologically acceptable to the oral tissues.

Eosinophilic gastroenteritis.

Four patients with eosinophilic gastroenteritis are presented to illustrate the protean manifestations of this disorder. While the cause is unknown, the complications many, and the differential diagnosis often challenging, the treatment is simple and consists of low-dose, alternate-day administration of corticosteroids. Diagnosis depends on gastrointestinal biopsy, which usually can be obtained without surgery.