The value of preplacement screening radiography of the low back.

Because there has not been a randomized controlled trial on the validity of preplacement screening radiography of the low back, the author assesses this procedure indirectly by reviewing empirical evidence concerning its usefulness in industrial settings and by evaluating it against the basic requirements of a successful screening test.

Detection of the traversability of surfaces by crawling and walking infants.

In four studies we investigated the perception of the affordance for traversal of a supporting surface. The surface presented was either rigid or deformable, and this property was specified either optically, haptically, or both. In Experiment 1A, crawling and walking infants were presented with two surfaces in succession: a standard surface that both looked and felt rigid and a deforming surface that both looked and felt nonrigid.

What does infant perception tell us about theories of perception?

The article begins with a summary of eight well-substantiated conclusions drawn from research on perception in infants that have implications for theories of perception. The following section examines several traditional and modern theories of perception in the light of these conclusions. Finally, some "big issues" that have divided perceptual and cognitive theories are discussed, with the suggestion that research on infants can help reconcile the divided camps.

Mineralogical studies of sulfide samples and volatile concentrations of basalt glasses from the southern Juan de Fuca Ridge.

Sulfide samples obtained from the U.S. Geological Survey's DSRV Alvin dives on the southern Juan de Fuca Ridge closely resemble those from the same area described by Koski et al.

A pyrolysis/gas chromatographic method for the determination of hydrogen in solid samples.

A method is described for the determination of hydrogen in solid samples. The sample is heated under vacuum after which the evolved gases are separated by gas chromatography with a helium ionization detector. The system is calibrated by injecting known amounts of hydrogen, as determined manometrically.

Use of central and peripheral optical flow in stance and locomotion in young walkers.

Young walkers (up to 5 years of age) were presented with optical flow in a moving room. Flow was global or was restricted to either the center or the periphery of the visible optic array. On standing trials the response rate was greatest when peripheral flow was available.

Acquired protein appetite in rats: dependence on a protein-specific need state.

Rats are shown to acquire a preference for protein-predictive olfactory cues which depends on a state of mild deficit in protein intake--i.e. a learned protein-specific appetite.

The mutagenicity of emissions from eight binder systems used in steel foundries.

Emissions generated when molten steel was poured into sand molds fabricated with eight different binder systems were collected separately and tested for mutagenic activity using the Ames Salmonella assay. The sampling device consisted of an initial 8 X 10 in. glass fiber filter in a custom fabricated apparatus through which air was drawn using a Hi-Vol motor and fan.

Topical therapy for oropharyngeal symptoms of myasthenia gravis.

Inhibitors of acetylcholinesterase are commonly used in the treatment of myasthenia gravis. We studied a patient with mainly bulbar myasthenia gravis who did not tolerate oral pyridostigmine despite a clear clinical response. Treatment with nebulized pyridostigmine reduced her symptoms without systemic side effects.

Gastromotor mechanism of fenfluramine anorexia.

A gastric slowing effect of fenfluramine accounts for most of the drug's suppressant effect on food intake in freely feeding rats. It is conceivable on the evidence to date that this gastromotor action of fenfluramine explains all its effects on appetite and metabolism, but additional peripheral and central effects--such as motor inhibition--are likely. Rate of gastric emptying is quantitatively the dominant physiological control of appetite: it determines the duration for which absorption of a meal sustains metabolic satiety; it also influences gastric distension, which can be a source of innate satiation and of learned carbohydrate-specific satiation.

The company doctor: an endangered species.

Company doctors are both managers and clinicians. They are responsible for managing human resources, occupational health professionals, technicians, and clerical staff. They are involved in prevention programs, and are expected to advise management of changes in occupational health, workers' compensation, and human rights legislation.

Sulfur in achondritic meteorites.

Total sulfur abundances have been measured for 48 achondrites. For twenty eucrites they ranged from 370 to 3700 micrograms S/g with a median sulfur content of 1180 micrograms S/g. Sulfur abundances for howardites ranged from 1490 to 3240 micrograms S /g and had a median sulfur concentration of 2340 micrograms S/g.

Norepinephrine-facilitated eating: reduction in saccharin preference and conditioned flavor preferences with increase in quinine aversion.

Paraventricular (PVN) hypothalamic norepinephrine (NE) injections which facilitated feeding were nonetheless found to reduce both the unconditioned preference for saccharin and starch-conditioned preferences for almond odor and lemon taste, as well as enhancing aversion to quinine. These results add to the evidence that PVN NE elicits eating by attenuating a satiety signal.

Identification of polycyclic aromatic compounds in mutagenic emissions from steel casting.

Workers in ferrous foundries show increased risk of lung cancer. In the steel casting process hot metal is poured into sand moulds solidified with organic binders, producing a plume of smoke containing a variety of organic compounds and showing strong mutagenicity in the Salmonella/S9 assay. We have collected the emissions produced when steel is poured into an experimental sand mould solidified with oil, clay and cereal, a widely used binder system.

Spectral and other physicochemical properties of submicron powders of hematite (alpha-Fe2O3), maghemite (gamma-Fe2O3), magnetite (Fe3O4), goethite (alpha-FeOOH), and lepidocrocite (gamma-FeOOH).

Spectral and other physicochemical properties were determined for a suite of submicron powders of hematite (alpha-Fe2O3), maghemite (gamma-Fe2O3), magnetite (Fe3O4), goethite (alpha-FeOOH), and lepidocrocite (gamma-FeOOH). The spectral reflectivity measurements were made between 0.35 and 2.

Fluid inclusions in stony meteorites--a cautionary note.

Newly discovered fluid inclusions in thin sections of Bjurbole chondrules, shergottite EETA79001, lunar meteorite ALHA81005, and Apollo 16 glasses possess physical properties similar to those fluid inclusions found in thin sections of five stony meteorites recently described by Warner et al. (1983). The distribution and physical properties of these new fluid inclusions indicate they may be artifacts of thin section preparation; we suggest that saw coolant was sucked into vacuum vesicles in glasses and minerals through submicroscopic fractures produced during sawing.

Determination of H2O and CO2 concentrations in fluid inclusions in minerals using laser decrepitation and capacitance manometer analysis.

Water and carbon dioxide concentrations within individual and selected groups of fluid inclusions in quartz were analyzed by using laser decrepitation and quantitative capacitance manometer determination. The useful limit of detection (calculated as ten times the typical background level) is about 5 x 10(-10) mol of H2O and 5 x 10(-11) mol of CO2; this H2O content translates into an aqueous fluid inclusion approximately 25 micrometers in diameter. CO2/H2O determinations for 38 samples (100 separate measurements) have a range of H2O amounts of 5.

Does laxative abuse control body weight? A comparative study of purging and vomiting bulimics.

This study examines the daily food intake and eating habits of 30 bulimia nervosa patients of normal weight; 20 vomited daily and 10 purged daily. The aim was to measure and compare food intakes and to examine the belief that laxative abuse is an effective means of controlling body weight. The results indicate that the purgers control their weight by overall dietary restraint, not by the pharmacological action of the laxatives.

Controlling weight by purgation and vomiting: a comparative study of bulimics.

This study assessed the efficacy of self-induced vomiting and purgation, respectively, in attempts at preventing weight gain in patients with bulimia. It was found that the vomiters ate significantly more yet weighed less: the purgers ate less but weighed significantly more. Such findings strongly suggest that excess purgation has little impact on intestinal absorption even at the doses used in bulimia.