BACKGROUND：Similar to handedness, hand clasping and arm folding are also lateral preferences. Previous studies showed a variation frequency for hand clasping and arm folding among different populations. OBJECTIVE： T...BACKGROUND：Similar to handedness, hand clasping and arm folding are also lateral preferences. Previous studies showed a variation frequency for hand clasping and arm folding among different populations. OBJECTIVE： To investigate the relationship between patterns of lateral preferences （hand clasping or arm folding） and academic performance of middle school students. DESIGN, TIME AND SETTINGS： Cross-sectional investigation. The data were collected in the Beijing Zhongguancun High School in Beijing in May 2007. Data analysis was performed in the State Key Laboratory of Cognitive Neuroscience and Learning, Beijing Normal University during June to July 2007. PARTICIPANTS： A total of 102 senior-grade students from Beijing Zhongguancun High School, including 58 males and 44 females, were selected for this study. METHODS： Different forms of hand clasping and arm folding were recorded. More specifically, hand clasping was either right-thumb-top or left-thumb-top, and arm folding was either right-arm-top or left-arm-top. Students with congruent preference used right-thumb-top-right-arm-top or left-thumb-top-left-arm-top, and incongruent preference was displayed by right-thumb-top-left-arm-top or left-thumb-top-right-arm-top. Academic performances were collected from midterm exams in six subjects （Chinese, Mathematics, English, Physics, Chemistry, and Biology）, with a total points = 100 for each. A three-way （hand clasping, arm folding, and sex） ANOVA was performed to determine the effect on academic performances. MAIN OUTCOME MEASURES： The relationship between hand clasping, arm folding, sex, and academic performance of students. RESULTS： （1） There was no significant difference in distribution frequency between right-thumb-top and left-thumb-top （P 〉 0.05）, or between right-arm-top and left-arm-top （P 〉 0.05）. The distribution frequency difference between boys and girls was not significant for any subtype （P 〉 0.05）. （2） hand clasping had no significant main effect on any of the six subjects （P 〉 0.05）. The right-arm-top students received significantly higher points in Chinese, Physics, Chemistry, and Biology, compared with the left-arm-top students （P 〈 0.05）. A significant sexual difference was detected in academic performance in Chinese and English; girls had higher scores than the boys （P 〈 0.05）. The students with congruent preference scored higher in English, compared with those with incongruent preference （P 〈 0.05）. CONCLUSION： The arm folding form of lateral preference had a significant effect on academic performance of middle school students, implying that this human laterality index is of great functional importance.展开更多
It is reported in this article that the mandibular unilateral distal-extension remova-ble partial dentures with wrvught wtre retentive clasp arm,cast circumferential retentive arm andI-bar retentive arm were tested un...It is reported in this article that the mandibular unilateral distal-extension remova-ble partial dentures with wrvught wtre retentive clasp arm,cast circumferential retentive arm andI-bar retentive arm were tested under vertical loading,and the stresses around the root of thetooth adjacent to the extension base were ovserved by means of photoeiastic stress analysis.The results showed that the retentive clasp arm or reciprocal clasp arm in distal-extension remov-able partial denture does not affect the magnitude and direction of the abutment tooth force,that there is no obvious difference among the wrought wire clasp arm,cast circumferential clasparm and I-bar clasp on the abutment tooth force,and that the force created due to loading of re-movable partial denture is transmitted to the primary abutment tooth mainly through theocclusal rest.展开更多
C lasp-pass移动是Habiro1993年在定向链环上引入的一个局部移动的概念.研究了几乎相邻的图,得到以下结论:对于一个几乎相邻图G,若它不包含价为1的顶点,则G的空间嵌入上的任意clasp-pass移动都可通过Δ-同伦来实现.作为推论,有:设f,g:G...C lasp-pass移动是Habiro1993年在定向链环上引入的一个局部移动的概念.研究了几乎相邻的图,得到以下结论:对于一个几乎相邻图G,若它不包含价为1的顶点,则G的空间嵌入上的任意clasp-pass移动都可通过Δ-同伦来实现.作为推论,有:设f,g:G→S3是价为3的几乎相邻图G的两个顶点同伦的嵌入,若对于任意(1;3)阶有限型A3-等价不变量φ,φ(f)=φ(g),则f和g一定是de lta顶点同伦的.展开更多
基金the National Natural Science of China, No. 30621130074
文摘BACKGROUND：Similar to handedness, hand clasping and arm folding are also lateral preferences. Previous studies showed a variation frequency for hand clasping and arm folding among different populations. OBJECTIVE： To investigate the relationship between patterns of lateral preferences （hand clasping or arm folding） and academic performance of middle school students. DESIGN, TIME AND SETTINGS： Cross-sectional investigation. The data were collected in the Beijing Zhongguancun High School in Beijing in May 2007. Data analysis was performed in the State Key Laboratory of Cognitive Neuroscience and Learning, Beijing Normal University during June to July 2007. PARTICIPANTS： A total of 102 senior-grade students from Beijing Zhongguancun High School, including 58 males and 44 females, were selected for this study. METHODS： Different forms of hand clasping and arm folding were recorded. More specifically, hand clasping was either right-thumb-top or left-thumb-top, and arm folding was either right-arm-top or left-arm-top. Students with congruent preference used right-thumb-top-right-arm-top or left-thumb-top-left-arm-top, and incongruent preference was displayed by right-thumb-top-left-arm-top or left-thumb-top-right-arm-top. Academic performances were collected from midterm exams in six subjects （Chinese, Mathematics, English, Physics, Chemistry, and Biology）, with a total points = 100 for each. A three-way （hand clasping, arm folding, and sex） ANOVA was performed to determine the effect on academic performances. MAIN OUTCOME MEASURES： The relationship between hand clasping, arm folding, sex, and academic performance of students. RESULTS： （1） There was no significant difference in distribution frequency between right-thumb-top and left-thumb-top （P 〉 0.05）, or between right-arm-top and left-arm-top （P 〉 0.05）. The distribution frequency difference between boys and girls was not significant for any subtype （P 〉 0.05）. （2） hand clasping had no significant main effect on any of the six subjects （P 〉 0.05）. The right-arm-top students received significantly higher points in Chinese, Physics, Chemistry, and Biology, compared with the left-arm-top students （P 〈 0.05）. A significant sexual difference was detected in academic performance in Chinese and English; girls had higher scores than the boys （P 〈 0.05）. The students with congruent preference scored higher in English, compared with those with incongruent preference （P 〈 0.05）. CONCLUSION： The arm folding form of lateral preference had a significant effect on academic performance of middle school students, implying that this human laterality index is of great functional importance.
文摘It is reported in this article that the mandibular unilateral distal-extension remova-ble partial dentures with wrvught wtre retentive clasp arm,cast circumferential retentive arm andI-bar retentive arm were tested under vertical loading,and the stresses around the root of thetooth adjacent to the extension base were ovserved by means of photoeiastic stress analysis.The results showed that the retentive clasp arm or reciprocal clasp arm in distal-extension remov-able partial denture does not affect the magnitude and direction of the abutment tooth force,that there is no obvious difference among the wrought wire clasp arm,cast circumferential clasparm and I-bar clasp on the abutment tooth force,and that the force created due to loading of re-movable partial denture is transmitted to the primary abutment tooth mainly through theocclusal rest.
