OBJECTIVE The aim was to investigate the in vitro fluoride release from fluoride varnishes under acidic conditions. STUDY DESIGN Poly(methyl methacrylate) blocks (Perspex, n=3 per group) were painted with 80 ± 5 mg fluoride varnish (n=10) and placed into artificial saliva for 30 min. Then, blocks were placed into either 1% citric acid (pH 2.27) or 0.3% citric acid (pH 3.75) solutions (n=3 per...

An impairment in learning to inhibit prepotent responses to positive stimuli is associated with damage to the orbitofrontal cortex (OFC) in rats, monkeys, and humans performing discrimination reversal, extinction, and detour reaching tasks. In contrast, a recent study showed that OFC-lesioned rhesus monkeys could learn to select the smaller of 2 quantities of food reward in order to receive the...

Propulsive activity of the human colon was measured with radiopaque markers (shapes), radiotelemetering capsules, Perspex capsules containing (51)Cr, or with free (51)Cr sodium chromate. Propulsive activity can be readily detected by these techniques, none of which requires the use of radiological contrast media. With capsules containing (51)Cr or with free (51)Cr repeated observations can be m...

1. The e.e.g. potentials are picked up by stainless steel screws inserted in the skull and are led via a multi-channel miniature electrical connector (ITT Cannon, Basingstoke) to the recorder. 2. The intraventricular cannula described by Hayden, Johnson & Maickel (1966) for use in the rat proved equally suitable for the rabbit. Constructed of Perspex, its lighter weight compared with that of co...

Conditions of Electrophoresis.-The apparatus used was similar to that described by Franglen (1953). It consisted of a flat shallow " perspex " box in which a sheet of Whatman No. 1 paper was stretched horizontally with the ends dipping into the electrode solutions. The paper was first wetted with electrolyte, blotted, and placed in position in the apparatus. Serum (10lI.) was then applied from ...

Introduction: Three physical conditions caused an external beam designated as a small field. The first is the loss of lateral charged particle equilibrium. The second is the effect of collimators on the primary photon source occlusion. The third condition is the size of the detector which is large compared to the field size. The most obvious perturbation effects in last condit...

We studied the capability of one male and one female harbour seal Phoca vitulina to discriminate diameter differences of circular discs by means of active touch with their mystacial vibrissae. To prevent the animals from perceiving visual information, they were blindfolded during trials. In a two-alternative forced-choice procedure, the seals were required to choose the larger of two Perspex di...

T he dynamics of the bottom zone of a narrow fluidized bed, from bubbling to turbulent regimes, was studied in a cold model of 0.1 m i.d. and 1.3 m high. Tested distributor types were perforated perspex plates, with six different perforation grids, metallic mesh and porous ceramic, with pressures drops ranging from 0.05 to 350 kPa, corresponding to superficial air velocities from 0.1 to 2.3 m s...

Extrinsic staining of teeth is a side-effect of some antiseptic mouthrinses. However, few of the many rinse products available to the general public have been investigated for their propensity to cause staining. Dietary factors play an aetiological role in staining and have been used in vitro to study and compare the activity of rinses. The aim of this study was to assess rinse products for sta...

Brachial artery ultrasound is commonly employed for noninvasive assessment of endothelial function. However, analysis is observer dependent and susceptible to errors. We describe studies on a computerized edge-detection and wall-tracking software program to allow more accurate and reproducible measurement. In study 1, three purpose-built Perspex phantom arteries, 3.00, 4.00, and 6.00 mm in diam...