Newborn response to auditory stimulus discrepancy     

M J Weiss  P R Zelazo  I U Swain 《Child development》1988,59(6):1530-1541

Newborns were assessed for their recovery of head turning toward laterally presented auditory stimuli (titi) that varied from a familiar standard on 1 of 5 levels of fundamental frequency. Following habituation to repeated standard trials, newborns recovered to 14% and 21%, but not to 0%, 7%, or 28% discrepancies, indicating that recovery was a quadratic function of the degree of stimulus-schema discrepancy. Moreover, newborns reliably turned away from the standard stimulus during posthabituation no-change control trials, indicating that the neural network associated with that stimulus was not fatigued. Infants in every condition showed recovery of head turning to a novel posttest stimulus (papa). These data are interpreted with a dual processing model postulated to include both reflexive (context-independent) orientation and stimulus-schema comparison process (context-dependent) orientation.  相似文献   

The relationship between leg preference and knee mechanics during sidestepping in collegiate female footballers     

Scott R. Brown  Henry Wang  D. Clark Dickin  Kaitlyn J. Weiss 《Sports biomechanics / International Society of Biomechanics in Sports》2014,13(4):351-361

This study examined the relationship between leg preference and knee mechanics in females during sidestepping. Three-dimensional data were recorded on 16 female collegiate footballers during a planned 45° sidestep manoeuvre with their preferred and non-preferred kicking leg. Knee kinematics and kinetics during initial contact, weight acceptance, peak push-off, and final push-off phases of sidestepping were analysed in both legs. The preferred leg showed trivial to small increases (ES = 0.19–0.36) in knee flexion angle at initial contact, weight acceptance, and peak push-off, and small increases (ES = 0.21–0.34) in peak power production and peak knee extension velocity. The non-preferred leg showed a trivial increase (ES = 0.10) in knee abduction angle during weight acceptance; small to moderate increases (ES = 0.22–0.64) in knee internal rotation angle at weight acceptance, peak push-off, and final push-off; a small increase (ES = 0.22) in knee abductor moment; and trivial increases (ES = 0.09–0.14) in peak power absorption and peak knee flexion velocity. The results of this study show that differences do exist between the preferred and non-preferred leg in females. The findings of this study will increase the knowledge base of anterior cruciate ligament injury in females and can aid in the design of more appropriate neuromuscular, plyometric, and strength training protocols for injury prevention.  相似文献   

Sport commitment among competitive female gymnasts: a developmental perspective     

Weiss WM  Weiss MR 《Research quarterly for exercise and sport》2007,78(2):90-102

The purpose of this study was to examine age and competitive level differences in the relationship between determinants and level of sport commitment. Gymnasts (N = 304) comprised three age groups (8-11, 11-14.5, and 14.5-18 years) and two competitive levels (Levels 5-6 and 8-10). Multiple regression analyses revealed: (a) perceived costs and social constraints from parents and best friends were the strongest predictors of commitment for the youngest gymnasts, (b) perceived costs, personal investments, and parent social constraints predicted commitment for 11-14.5-year-old gymnasts, and (c) perceived competence and costs predicted commitment for the oldest gymnasts. Competitive level differences also emerged; for Level 5-6 gymnasts, personal investments, perceived costs, coach social support, and social constraints by coach, best friend, and teammates were predictors of commitment. Personal investments and teammate social constraints were significant predictors for Level 8-10 gymnasts. Developmental factors and additional determinants are important to consider in further studies of the sport commitment model.  相似文献   

A new class of gels for the conservation of painted surfaces     

Emiliano Carretti  Luigi Dei  Richard G. Weiss  Piero Baglioni   《Journal of Cultural Heritage》2008,9(4):386-393

The application of a new class of organogels as cleaning tools for painted surfaces is described. It combines some of the most attractive features of cleaning liquids and normal gels while diminishing the deleterious characteristics of both. Thus, the ‘latent’ gellant, polyethyleneimine (PEI), reacts with CO₂ at room temperature in solutions of several organic liquids to produce an ammonium carbamate form (PEICO₂). This charged species organizes itself into 3D polymer networks which immobilize the liquids as gels. The properties of the original solution (i.e. a free-flowing liquid) are re-established immediately after addition of a small amount of a weak acid which displaces the CO₂ molecules and makes the PEI chains positively charged. The visual changes are substantiated by rheological analyses. Results from analytical tests to determine the utility of these gels as cleaning tools for painted surfaces of historical and artistic interest, have been obtained from contact angle and FTIR measurements as well as visual comparisons of the surfaces before and after application of the gels. The analyses indicate that the PEICO₂-based organogels were very effective in removing different surface patinas from painted supports. A surface layer of dammar was completely removed from a test canvas with oil paint, an aged painting from the XIX century, and a XV century oil-on-wood panel attributed to Mariotto di Cristoforo. Finally, a surface acrylic polymeric resin (used in a restoration performed during the 1960s) was also successfully removed from Renaissance wall paintings decorating the Santa Maria della Scala Sacristy in Siena, Italy. The isothermally rheoreversible gel approach described in this work represents a new, highly versatile, and very efficient method for removing aged surface patinas from works of art.  相似文献   

A new family of high viscosity polymeric dispersions for cleaning easel paintings     

Emiliano Carretti  Irene Natali  Caterina Matarrese  Paola Bracco  Richard G. Weiss  Piero Baglioni  Antonella Salvini  Luigi Dei   《Journal of Cultural Heritage》2010,11(4):1555-380

The procedures for making and applying a new family of high viscosity aqueous polymeric dispersions based on poly(vinyl alcohol)-borax (PVA-borax) matrices are presented. A specific system of this type has been used to remove an oxidized varnish coating from the surface of “Coronation of the Virgin with Saints”, a 15th century egg tempera painting on wood by Neri di Bicci (Florence, 1418–1492). FTIR spectra showed that the oxidized varnish was constituted of highly aged shellac resin. Good cleaning performance was attained when the liquid portion of the dispersion consisted of a mixture of water and acetone. Rheological investigations indicate that the acetone content does not affect the mechanical properties of the polymeric dispersion. Those mechanical properties permit easy removal of the cleaning agent simply by peeling it from the surface by means of a forceps or spatula once it has carried out its cleaning function. Optical microscopic and FTIR investigations show that the cleaning agent is able to remove the oxidized varnish coating from the surface of the Neri di Bicci painting without leaving detectable residues.  相似文献