Psychology and genetics: A happy marriage?

Presents a lecture delivered at the 1980 meeting of the Canadian Psychological Association. The present status of behavior genetics is reviewed. The nature-nurture issue is considered, and research on the genetic–environment interaction is advocated. Many hybrid sciences use reductionism to explain the phenomena of complex systems by the principles of the more basic sciences that deal with the component parts of these systems. A reductionistic view of behavior genetics is rejected; instead, the author prefers an approach that examines how biological factors directly influence behavior. Current trends in behavior genetics are identified. (French abstract) (24 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Neurophysiological development in premature infants following stimulation.

Tactile kinesthetic stimulation was given to 15 premature infants to determine effects on neurophysiological development. The mothers of the Ss were trained to administer the treatment for 15 min 4 times a day for 1 mo, beginning the day the S arrived home from the hospital. When Ss and 14 control Ss were 4 mo old (CA), they were examined by a pediatrician, a psychologist, and a pediatric nurse who had no knowledge of whether the S was experimental or control. The Ss' neurological development, weight, length, head circumference, and mental and motor development (as determined by the Bayley Scales of Infant Development) were assessed. Results indicate that experimental Ss made significant gains in neurological development, in weight gain, and in mental development. Findings suggest that the early and systematic stimulation provided by the mothers can enhance development of premature infants. (24 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Dependence of electrical properties of polycrystalline cvd si films on grain size and impurity doping concentrationa,b

The electrical properties of sets of simultaneously grown p-type polycrystalline Si films, deposited by SiH₄ pyrolysis on polycrystalline high-purity alumina substrates and B-doped during growth, were determined by Hall-effect measurements in the temperature range 77-420K as functions both of impurity doping concentration N (~10^l5 to ~10²⁰cm⁻³) and average grain size (≈1 to ≈125μm) in the film. Room temperature data showed rapidly increasing resistivities and rapidly decreasing free-carrier concentrations for doping below a critical concentration N_m and distinct mobility minima at that concentration, with the value of N_m being larger the smaller the average grain size. Measurements as a function of sample temperature showed the intergrain barrier height E_b, decreasing from a maximum value of ~0.4eV at the critical concentration to very small values (~0.01eV) for concentrations above 10¹⁹cm⁻³, with a functional dependence close to E_b ∝l/N^1/2 and E_b for any given concentration being larger the smaller the average grain size. Results are interpreted in terms of the grain-boundary trapping model. Trapped carrier densities in the grain boundaries were calculated to range from ~5×l0¹¹cm⁻² at N≈N_m to ~5×l0¹²cm⁻² for N>10¹⁹cm⁻³, the density being higher the smaller the grain size, and evidence was found for an energy distribution of traps in the Si bandgap, rather than a fixed density at a single discrete energy level. The observed relationship between N_m and average grain size nearly coincides with that of the model for films with ~lμm grain size but sharply departs from it for larger grain sizes, indicating probable applicability of the model for grain sizes up to that range. ^aThis work was supported by the U.S. Department of Energythrough its San Francisco Operations Office under Contract DE-AC03-79ET23045 and monitored by the Solar Energy Research Institute, Golden, CO. bThese results were first described at the 22nd Electronic Materials Conference, Ithaca, NY, June 21–27, 1980, Paper No. M4.     

Properties of carboxymethylated cotton prepared in nonaqueous media

Mercerized cotton printcloth was converted to sodium cellulosates of various degrees of substitution by reaction with sodium methoxide in methanol. These sodium cellulosates were reacted with sodium monochloroacetate in dimethyl sulfoxide at room temperature. The sodium hydroxide pretreatment affected not only the yield of the sodium cellulosate but also the degree of conversion of cellulosate to carboxymethyl (CM) cellulose. The nonaqueously prepared CM cottons had fabric properties that differed from the properties of CM cottons prepared by conventional aqueous methods. By the nonaqueous method, CM cottons of increased capacity, or degree of substitution (D.S.), were obtained by a one-treatment procedure. These CM cottons in the sodium salt or acid form were insoluble in water and in 23% NaOH. Those of D.S. of about 0.3, when in the acid form, possessed improved wrinkle recovery angles. The salt form of CM cotton acts as a built-in catalyst for the reactions of cotton with methylolated ureas such as dimethylolurea (DMU) and dimethylolethyleneurea (DMEU). However, only DMU was effective in imparting improved conditioned and wet wrinkle recovery to CM cotton. Initial replacement of Na⁺ ions of CM cotton by H⁺ was easily accomplished. After replacement of approximately half of the Na⁺ ions, it was more difficult to replace the remaining half of Na⁺ from CM cottons that had been prepared in nonaqueous media. Affinity of carboxylate ions in CM cottons prepared nonaqueously for cations did not decrease with size of cation even though affinity for H⁺ ions was greatest.     

Hydroxyaliphatic acids in branched copolymers with acyl chloride-terminated long side chains: A new shrink-resist treatment for wool

Two synthetic routes were followed to prepare graft copolymers with long side chains containing acyl chloride terminal groups. In the first of these methods acryloxy aliphatic acyl chlorides were synthesized from ricinoleic acid, 12-hydroxystearic acid and 10-hydroxydecanoic acid and then polymerized with other acrylate ester comonomers. In the second procedure, a prepolymer was formed by copolymerizing acryloyl chloride with acrylate esters. The prepolymer then was treated with 12-hydroxystearic acid or 9(10)-hydroxymethylstearic acid to produce polymers with side chains having terminal carboxylic acid groups. These polymers were made more reactive by conversion to acid chlorides. The active polymers were applied to wool fabrics; the imparted shrink-resistance was durable under an accelerated wash test procedure. An added advantage of the treatment is a soft “hand” or feel resulting from internal plasticization of the polymer coating. No. Market. Nutr. Res. Div., ARS, USDA. W. Market, Nutr. Res. Div. ARS, USDA.     

Modulating functional loop movements: the role of highly conserved residues in the correlated loop motions

Loop flexibility in enzymes plays a vital role in correctly positioning catalytically important residues. This strong relationship between enzyme flexibility and function provides an opportunity to engineer new substrates and inhibitors. It further allows the design of site-directed mutagenesis experiments to explore enzymatic activity through the control of flexibility of a functional loop. Earlier, we described a novel mechanism in which a small loop triggers the motions of a functional loop in three enzymes (beta-1,4-galactosyltransferase, lipase, and enolase) unrelated in sequence, structure, or function. Here, we further address the question of how the interactions between various flexible loops modulate the movements of the functional loop. We examine beta-1,4-galactosyltransferase as a model system in which a Long loop undergoes a large conformational change (moves in space up to 20 A) upon substrate binding in addition to a small loop (Trp loop) that shows a considerably smaller conformational change. Our molecular-dynamics simulations carried out in implicit and explicit solvent show that, in addition to these two loops, two other neighboring loops are also highly flexible. These loops are in contact with either the Long loop or the Trp loop. Analysis of the covariance of the spatial displacement of the residues reveals that coupled motions occur only in one of these two loops. Sequence analysis indicates that loops correlated in their motions also have highly conserved residues involved in the loop-loop interactions. Further, analysis of crystal structures and simulations in explicit water open the possibility that the Trp loop that triggers the movement of the Long loop in the unbound conformation may also play the same role in the substrate-bound conformation through its contact with the conserved and correlated third loop. Our proposition is supported by the observation that four of the five conserved positions in the third loop are at the interface with the Trp loop. Evolution appears to select residues that drive the functional Long loop to a large conformational change. These observations suggest that altering selected loop-loop interactions might modulate the movements of the functional loop.