制动盘表面螺旋纹理的消除方法

创新要点：提出以冲刷代替传统磨削过程对制动盘进行抛光;研究扶取规定表面质晕下的最优冲刷条件。     

Effective body water and body mass changes during summer ultra-endurance road cycling

Because body mass change (ΔM_b) does not represent all water losses and gains, the present field investigation determined if (a) ΔM_b equalled the net effective body water change during ultra-endurance exercise and (b) ground speed and exercise duration influenced these variables. Thirty-two male cyclists (age range, 35–52 years) completed a 164-km event in a hot environment, were retrospectively triplet matched and placed into one of three groups based on exercise duration (4.8, 6.3, 9.6 h). Net effective body water loss was computed from measurements (body mass, total fluid intake and urine excreted) and calculations (water evolved and mass loss due to substrate oxidation, solid food mass and sweat loss), including (ΔEBW_gly) and excluding (ΔEBW) water bound to glycogen. With all cyclists combined, the mean ΔM_b (i.e. loss) was greater than that of ΔEBW_gly by 1200 ± 200 g (P = 1.4 × 10^–18), was similar to ΔEBW (difference, 0 ± 200 g; P = .21) and was strongly correlated with both (R² = .98). Analysis of equivalence indicated that ΔM_b was not equivalent to ΔEBW_gly, but was equivalent to ΔEBW. Due to measurement complexity, we concluded that (a) athletes will not calculate the effective body water calculations routinely and (b) body mass change remains a useful field-expedient estimate of net effective body water change.     

Is university internationalization bad for performance? Examining two different types of diversity

While most studies on diverse organizations have been directed at business organizations, the academic sector has also become increasingly international and heterogeneous. Few large-scale studies have investigated multicultural academic departments and none of those have dealt with diversity and group processes. Therefore, a survey was directed towards academics in 16 science departments in three large universities in Denmark. Results based on the response from 489 academics showed that cultural diversity, as a deep level heterogeneity, was positively related to performance and satisfaction, whereas gender diversity, as a surface level heterogeneity, was negatively associated with satisfaction. Implications of these findings are discussed in detail.     

Between the estate and the state: struggling to be a ‘good’ mother

The paper draws on an ESRC‐funded study of 70 families in two London locations. It focuses on a set of contemporary and contradictory political discourses that work on and through the lives of working‐class mothers and thereby create tensions and impossibilities within their lives. We illustrate the ways in which these women are positioned by and within these discourses in ways that leave them vulnerable to political and media criticisms.     

Local links,local knowledge: Choosing care settings and schools

This article draws on data from two recently completed Economic and Social Research Council funded projects in order to examine class differences and similarities in choice of school and choice of childcare. The authors argue that there is every reason to believe that in many circumstances, within its particular mechanisms and practices, choice produces specific and pervasive forms of inequity. The processes by which working‐class parents in one study chose care settings and schools could be seen as less skilled, less informed, less careful than the decision making of many of the middle‐class respondents. However, this is not an argument that the authors advance, noting instead that the practices and meanings of choice are subject to significant social, cultural and economic variations in terms of who gets to choose, who gets their choices, and what, how and why people choose when they are able to. The authors argue that there are alternative sets of priorities in play for the working‐class respondents, involving attachments to the communal and the local.     

Influence of bench angle on upper extremity muscular activation during bench press exercise

This study compared the muscular activation of the pectoralis major, anterior deltoid and triceps brachii during a free-weight barbell bench press performed at 0°, 30°, 45° and –15° bench angles. Fourteen healthy resistance trained males (age 21.4 ± 0.4 years) participated in this study. One set of six repetitions for each bench press conditions at 65% one repetition maximum were performed. Surface electromyography (sEMG) was utilised to examine the muscular activation of the selected muscles during the eccentric and concentric phases. In addition, each phase was subdivided into 25% contraction durations, resulting in four separate time points for comparison between bench conditions. The sEMG of upper pectoralis displayed no difference during any of the bench conditions when examining the complete concentric contraction, however differences during 26–50% contraction duration were found for both the 30° [122.5 ± 10.1% maximal voluntary isometric contraction (MVIC)] and 45° (124 ± 9.1% MVIC) bench condition, resulting in greater sEMG compared to horizontal (98.2 ± 5.4% MVIC) and –15 (96.1 ± 5.5% MVIC). The sEMG of lower pectoralis was greater during –15° (100.4 ± 5.7% MVIC), 30° (86.6 ± 4.8% MVIC) and horizontal (100.1 ± 5.2% MVIC) bench conditions compared to the 45° (71.9 ± 4.5% MVIC) for the whole concentric contraction. The results of this study support the use of a horizontal bench to achieve muscular activation of both the upper and lower heads of the pectoralis. However, a bench incline angle of 30° or 45° resulted in greater muscular activation during certain time points, suggesting that it is important to consider how muscular activation is affected at various time points when selecting bench press exercises.     

Margarita glasses and high heels: How attention to shape,age, and vocabulary impacts children's recognition of typical and atypical exemplars

Children's ability to recognize object shape is foundational for successful early word learning. However, the prototypical shape of objects may not be easily accessible—take margarita glasses, for instance. The current study examined 304 U.S. children 17- to 42-month-old (152 females) from 2017 to 2020, asking how shape, age, and vocabulary abilities predict recognition of everyday objects. Children's ability to recognize objects increases with age and vocabulary, replicating prior work. Moreover, performance was partially moderated by object's typicality and shape features, and children's own attention to shape (shape bias) may mediate the effect, especially with prototypically shaped objects. The current study highlights how both child-specific variables and context features interact to shape language abilities, underscoring the emergent and multi-causal nature of word learning.