The effects of mid-flight whole-body and trunk rotation on landing mechanics: implications for anterior cruciate ligament injuries     

Meghan L. Critchley  Daniel J. Davis  Michaela M. Keener  Jacob S. Layer  Margaret A. Wilson  Qin Zhu 《Sports biomechanics / International Society of Biomechanics in Sports》2020,19(4):421-437

ABSTRACT

The purpose was to quantify the effects of mid-flight whole-body and trunk rotation on knee mechanics in a double-leg landing. Eighteen male and 20 female participants completed a jump-landing-jump task in five conditions: no rotation, testing leg ipsilateral or contralateral (WBRC) to the whole-body rotation direction, and testing leg ipsilateral (TRI) or contralateral to the trunk rotation direction. The WBRC and TRI conditions demonstrated decreased knee flexion and increased knee abduction angles at initial contact (2.6 > Cohen’s dz > 0.3) and increased peak vertical ground reaction forces and knee adduction moments during the 100 ms after landing (1.7 > Cohen’s dz > 0.3). The TRI condition also showed the greatest knee internal rotation angles at initial contact and peak knee abduction and internal rotation angles and peak knee extension moments during the 100 ms after landing (2.0 > Cohen’s dz > 0.5). Whole-body rotation increased contralateral knee loading because of its primary role in decelerating medial-lateral velocities. Trunk rotation resulted in the greatest knee loading for the ipsilateral knee due to weight shifting and mechanical coupling between the trunk and lower extremities. These findings may help understand altered trunk motion in anterior cruciate ligament injuries.  相似文献   

Prosodic correlates of stress in babbling: an acoustical study     

Davis BL  MacNeilage PF  Matyear CL  Powell JK 《Child development》2000,71(5):1258-1270

Prelinguistic babbling often seems remarkably speech-like, not because it has recognizable words but because it seems to have adult-like prosody. To quantify this impression, we compared disyllabic sequences from five infants and five adults in terms of the use of frequency, intensity, and duration to mark stress. Significantly larger values for the three acoustic variables were observed on stressed than on unstressed syllables independent of syllable position for both groups. Adults showed the correlates of utterance final syllables--lower f0, lower intensity, and longer duration; infants showed only decrease in intensity. Ratios for stressed to unstressed syllables and participation of the three variables in stress production in individual disyllables were highly similar in both groups. No bias toward the English lexical trochaic stress pattern was observed. We conclude that infants in English environments produce adult-like stress patterns before they produce lexical items, which specify stress. Acoustic and perceptual analyses are used to explore stress marking by prelinguistic infants in an English language environment. Results show that infants employ the three acoustic correlates of stress in individual syllables in a manner largely similar to that of adult speakers, although they do not show second-syllable declination effects or an English language trochaic stress bias.  相似文献   

Effects of organizational pictures and modality as a feedback strategy on learner comprehension and satisfaction     

Albert D. Ritzhaupt  Raymond Pastore  Jiahui Wang  Robert O. Davis 《Educational technology research and development : ETR & D》2018,66(5):1069-1086

One of the strongest instructional interventions documented in educational literature is the use of feedback to influence learning outcomes. However, there is lack of empirical research specifically pertaining to the use of multimedia in the feedback message. The purpose of this research was to test whether organizational pictures and modality as a feedback strategy had an effect on learner comprehension and satisfaction. The research design was a 2 Multimedia (Picture Present vs. Picture Absent) × 2 Modality (Narration vs. On-screen Text) × Trial (Trial 1 vs. Trial 2) with Multimedia and Modality serving as between-subject conditions and Trial serving as a repeated measure. One-hundred fifteen university students participated in the study. Findings show statistically significant increases in comprehension scores from Trial 1 to Trial 2 assessments for all four treatment conditions. Learners in the Picture present conditions were statistically more satisfied with the learning experience. Additionally, we used eye-tracking to verify the extent to which the pictures were used in the feedback message. A discussion and recommendations for future research and feedback design are provided.  相似文献   

Using conjoint analysis to examine bias in referral to a behavior intervention program     

Amity Noltemeyer  Claire Kunesh  Erin Harper  Darrel R. Davis 《Psychology in the schools》2021,58(1):89-106

Research in the United States suggests that teachers view Black students' misbehavior as more likely to reoccur, but such research has not disentangled the effect of race from related factors. We used conjoint analysis to experimentally test the effect of multiple student characteristics on the chances of being referred for a behavior intervention program. Although preservice teacher participants were not more likely to refer Black students, they were more likely to refer students who had lower grades, lived in poverty, lived with a single mother, and had been retained. We interpret these results and highlight directions for future research and practice.  相似文献   

Word recognition versus sentence comprehension on a speechreading task     

J E Dancer  P N Davis  J O'Neil 《American annals of the deaf》1987,132(1):43-45

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Fear potentiation of the acoustic startle reflex using noises of various spectral frequencies as conditioned stimuli     

Serge Campeau  Michael Davis 《Learning & behavior》1992,20(2):177-186

The effectiveness of noise of various intensities and frequencies in modulating the amplitude of the acoustic startle reflex was evaluated, as a preliminary test of the capacity of these noises to produce consistent and reliable fear-potentiated startle in rats. It was determined that bands of noise containing high frequencies (greater than 10 kHz) tend to unconditionally reduce acoustic startle responses, probably by masking the high-frequency startle-eliciting stimulus. Noise containing high frequencies produced reliable fear-potentiated startle only when its estimated unconditioned startle suppression was subtracted from the enhancement obtained after pairing it with footshocks. Noises devoid of high frequencies produced modest-unconditioned startle enhancements and the most robust and reliable fear-potentiated startle when they were paired with footshocks. A nonmonotonic relationship between training shock intensity and the level of fear-potentiated startle was also exhibited when a low-frequency noise was used as a conditioned stimulus, a finding consistent with previous studies in which a visual stimulus was used. Finally, a differential Pavlovian conditioning procedure indicated that rats could readily discriminate between two different low-frequency bands of noise. The outcome of these experiments indicates that it is easier to employ low-frequency bands of noise to obtain auditory fear-potentiated startle with high-frequency startle-eliciting stimuli.  相似文献   

Raising Reading Standards: What is the Headteacher's Role?     

Eve Bearne 《Literacy》1996,30(1):2-8

The role of the headteacher has been identificed as one of the key characteristics of schools which achieve high standards of reading. Eve Bearne here presents the findings of an evaluation which reveals ways in which headteachers influence reading standards, particularly through in-service provision. The evaluation's aim was to assess the effectiveness of in-service courses in raising standards of achievement in reading and to consider the implications for school provision and future in-service arrangements. One factor which emerged strongly was the importance of the headteacher's role in managing reading provision in the primary school. It appeared that where the headteacher had taken a proactive role, developments were likely to be more firmly and permanently established and staff more secure in extending their practice.  相似文献   

Deaf college students' comprehension of relational language in arithmetic compare problems     

Kelly RR  Lang HG  Mousley K  Davis SM 《Journal of deaf studies and deaf education》2003,8(2):120-132

In this study of deaf college students' performance solving compare word problems, relational statements were either consistent or inconsistent with the arithmetic operation required for the solutions. The results support the consistency hypothesis Lewis and Mayer (1987) proposed based on research with hearing students. That is, deaf students were more likely to miscomprehend a relational statement and commit a reversal error when the required arithmetic operation was inconsistent with the statement's relational term (e.g., having to add when the relational term was less than). Also, the reversal error effect with inconsistent word problems was magnified when the relational statement was a marked term (e.g., a negative adjective such as less than) rather than an unmarked term (e.g., a positive adjective such as more than). Reading ability levels of deaf students influenced their performance in a number of ways. As predicted, there was a decrease in goal-monitoring errors, multiple errors, and the number of problems left blank as the reading levels of students increased. Contrary to expectations, higher reading skills did not affect the frequency of reversal errors.  相似文献   

Better beware: comparing metacognition for phishing and legitimate emails     

Canfield  Casey Inez  Fischhoff  Baruch  Davis  Alex 《Metacognition and Learning》2019,14(3):343-362

Metacognition and Learning - Every electronic message poses some threat of being a phishing attack. If recipients underestimate that threat, they expose themselves, and those connected to them, to...  相似文献   

Characteristics of poor readers of Korean hangul: Auditory,visual and phonological processing     

Kim  Jeesun  Davis  Chris 《Reading and writing》2004,17(1-2):153-185

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