The structure of conversations with 6- to 10-year-old deaf children

In stage 1 classroom conversations between sixteen teachers and their pre-lingually deaf children were videotaped and analysed to examine both the styles used by teachers in controlling conversation and the functions pursued in dialogue. In stage 2 a sub-sample of four teachers with twenty children of known hearing losses and non-verbal intelligence was analysed in greater detail to examine relationships between these factors, teaching styles and the child's performance in dialogue. The analyses show that deaf children respond in a similar fashion to young hearing children in the way they react to different styles of teacher talk; that teachers differ in the functions they pursue in conversation; and that functions change as a consequence of the child's hearing loss but not mental age. The implications of the findings for linguistic development in pre-lingually deaf children are explored.

Use of FITC-protein A in place of fluorescein-conjugated anti-gammaglobulins for rapid virus diagnosis by immunofluorescence

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Endocrine correlates of behavioural oestrus in the female giant panda (Ailuropoda melaneleuca) and associated hormonal changes in the male

Urinary excretion of oestrogens and androgens by a pair of giant pandas was monitored by radioimmunoassay during behavioural oestrus through two successive breeding seasons. The excretion of oestrogens by the female was at a maximum during the proceptive period and lower during the period of receptivity. In the first breeding season studied, elevated androgen excretion in the male coincided with peak receptivity in the female. The study indicates that accurate timing of natural mating or artificial insemination could be achieved by monitoring oestrogen excretion in the female.

Brain-to-blood and saliva-to-blood mepivacaine ratios in rats

Mepivacaine hydrochloride, 25 and 50 mg/kg sc (with sacrifice at 15 min) produced higher (p less than 0.005) drug levels in neonate (24--36-hr-old) rat brain and blood than in adult rat brain and blood; however, there was no significant difference in the brain-to-blood ratio of the drug between neonates and adults at either dose level. Intraarterial infusion of mepivacaine hydrochloride (20 micrograms/min) in adult rats resulted in measurable (GLC) mepivacaine base levels in pilocarpine-induced parotid salivary secretions collected throughout 30- and 45-min infusion periods. The saliva-to-blood ratios (+/- SEM) of mepivacaine base were 0.64 +/- 0.13 after a 30-min infusion and 2.13 +/- 0.48 after a 45-min infusion.

Mortality patterns among workers in a gray iron foundry

The long-term mortality experience of 2861 men employed for at least one month in the period 1938 to 1967 in a gray iron foundry was examined to determine if they experienced unusual death rates for specific causes indicative of exposure to hazardous materials in the work environment. Both white and non-white workers experienced favorable mortality for most major disease categories compared to general population rates, even men employed five or more years. No deaths from pneumoconiosis were observed nor were deaths from other chronic respiratory diseases in excess. Analysis of detailed cancer sites showed no significant departures from expectation overall. However, in the subgroup of men who achieved five or more years employment prior to 1938, a twofold increase in mortality from digestive cancer (14 observed deaths vs. 7.4 expected) and respiratory cancer (8 observed deaths vs. 4.0 expected) was seen. Absence of information on specific foundry jobs held by the subjects and associated exposures limits full interpretation of the findings. However, the excess observed for respiratory cancer among long-term employees followed for 30 years is consistent with previous reports.

Development of a spin assay for reserve bilirubin loading capacity of human serum

The capacity of human serum albumin to bind bilirubin is of paramount importance in the prevention of neurological damage due to hyperbilirubinemia in the neonate. Currently, there is no rapid, reliable method to determine the reserve bilirubin loading capacity of serum albumin. A method using electron spin resonance spectroscopy with a dianionic spin-label molecular probe [1-N-(2,2,6,6-tetramethyl-1-oxyl-4-piperidinyl)-5-N-(1-aspartate)-2,4-dinitrobenzene] is presented which yields the reserve binding capacity of the bilirubin high-affinity binding site on human serum albumin and reserve bilirubin loading capacity of serum in mg/dl. Clinical validation of this spin assay may improve the neonatal care of jaundiced newborns.

Effect of temperature and protonation upon the conformation of 2'-o-methyladenosine. Correlation of conformational parameters in purine nucleosides

Proton magnetic resonance studies of 2'-o-methyladenosine in 2H2O have been carried out at variable temperature and p2H. The chemical shifts and H-H coupling constants are discussed in terms of the molecular conformation. Comparison of the data with those of adenosine reveals that 2'-O-methylation has little influence on the conformation. At neutral p2H where the adenine base is not protonated, the molecules favor a 2' endo, gauche-gauche conformation. Protonation of the base at the N(1) position leads to a decrease in the 2' endo, gauche-gauche bias. The data for 2'-O-methyladenosine and adenosine, as well as for several other purine derivatives, reveal the presence of a correlation between the sugar pucker and the C(5')-C(4') conformer distribution which is the inverse of the correlation previously reported for pyrimidine derivatives.

Stereochemistry of Hexahydrocarbazoles; the Temperature-dependent Nuclear Magnetic Resonance Spectra of N-Acetyl Derivatives

The configuration of certain substituted hexahydrocarbazoles 2, of significance in connection with earlier work, has been established. A study of the temperature dependence of the n.m.r. spectra of N-acetyl derivatives, initiated with the intention of distinguishing between cis- and trans-fused isomers, has led to the conclusion that the distinction could not be made on this basis since all of the temperature-dependent phenomena, even in cases where the cis-fusion had been established by other means, could be associated with rotational isomerism of the N-acetyl group and no observable effects in the temperature range studied could be related to conformational mobility of the ring system. Nevertheless, the results obtained provide information of value and interest regarding the stereochemistry of hexahydrocarbazoles.

Nuclear Magnetic Resonance Evidence Concerning the Effect of Remote Polar Substituents upon Conformational Equilibrium in Substituted Ethanes

The vicinal coupling constants of 1-(4-X-phenyl)-1,2-dibromoethanes vary with substituent. The coupling constants correlate with parameters which measure the polarity of the C—X bond. It is concluded that the observed changes in coupling constants with substituent are due to electrostatic interactions between the C—X and C2—Br bonds. Two different types of electrostatic calculations confirm that this interaction should stabilize the rotamers in which the phenyl and C2—Br groups are in a gauche orientation when the C—X group has polarity Cδ+—Xδ−.

Effect of Solvent Upon the Vicinal Proton Coupling Constants of Complex Substituted Ethanes. II. Anomalous Results for 1-Phenyl-1,2,2-trihaloethanes

The n.m.r. spectra of 11 tetra-substituted ethanes have been obtained in a number of solvents. Changes in the vicinal coupling constants of 1-phenyl-1,2,2-trihaloethanes with solvent do not fit the electrostatic model for solvent effects. It is concluded that the theory breaks down because solute–solvent hydrogen bonding specifically favors the trans rotamers of these compounds. The conditions under which the theory would be expected to break down are also discussed in more general terms.

A Boundary-Layer Theory for Transient Viscous Losses in Turbulent Flow

A laminar boundary-layer model is proposed to account for viscous losses during the transient turbulent flow of a liquid in a tube. In this model, inviscid slug flow is assumed for the core and all viscous effects are assumed to occur in the boundary layer. The transient boundary-layer velocity distribution is determined as a function of a prescribed variation in core velocity and the associated pressure gradient. Both analytical and numerical solutions are presented. This transient flow information is used to calculate local and integrated energy dissipation rates which are then combined, with one-dimensional energy analyses. The result is a prediction of the decrease in pressure-wave magnitude due to viscous dissipation, and a comparison is made with experimental data for rapid flow extinction. Good agreement between the observed and predicted results is obtained.

Effect of solvent and temperature upon the rotationally averaged vicinal coupling constants of some substituted 1,2-dibromoethanes

The solvent dependence of vicinal coupling constants has been investigated for (1,2-dibromoethyl)-benzene and three of its 4-substituted derivatives and for threo- and erythro(1,2-dibromopropyl)benzene. The temperature dependence of the vicinal coupling constants of three of the compounds has also been investigated. The difference between the two vicinal coupling constants of (1,2-dibromoethyl)benzene is dependent upon solution dielectric constant (in non-aromatic solvents) while the sum of coupling constants remains constant. The relative stabilities of its three rotamers are deduced from this information. A polar substituent in the 4-position does not affect the rotational equilibrium in any predictable manner. The vicinal coupling constant of threo(1,2-dibromopropyl)benzene is strongly solvent dependent. The relative stabilities of its three rotamers are deduced from the observation that the vicinal coupling constant is temperature independent. The most stable rotamer of erythro(1,2-dibromopropyl)-benzene is deduced from the observation that the vicinal coupling constant is large and independent of solvent. Factors affecting conformational preference are deduced. It is concluded that dipolar interactions are as important as steric interactions.