The influence of familiarization sessions on the stability of ramp and ballistic isometric torque in older adults

Ramp isometric contractions determine peak torque (PT) and neuromuscular activation (NA), and ballistic contractions can be used to evaluate rate of torque development (RTD) and electrical mechanical delay (EMD). The purposes of this study were to assess the number of sessions required to stabilize ramp and ballistic PT and to compare PT and NA between contractions in older adults. Thirty-five older men and women (age 63.7 ± 3.7 yr, body mass 64.3 ± 10.7 kg, height 159.2 ± 6.6 cm) performed 4 sessions of unilateral ramp and ballistic isometric knee extension, 48 hr apart. PT significantly increased (main time effect p < .05) from the first to the third session, with no further improvements thereafter. There was a trend toward higher PT in ballistic than in ramp contractions. No difference between contraction types on EMG values was observed. Therefore, the authors suggest that 3 familiarization sessions be performed to correctly assess PT. In addition, PT, NA, RTD, and EMD can be assessed with ballistic contraction in older adults.     

地层压力实时监测系统的设计

介绍了一种实用的地层压力实时监测系统，其中利用PS2101进行压力数据采集，并由计算机对数据实时分析处理，从而及时控制钻探过程．文章给出了系统硬件结构总框图和软件设计程序流程图，并作了较详细的分析．     

Comparing Fits of Latent Trait and Latent Class Models Applied to Sparse Binary Data: An Illustration with Human Resource Management Data

This paper addresses the problem of comparing the fit of latent class and latent trait models when the indicators are binary and the contingency table is sparse. This problem is common in the analysis of data from large surveys, where many items are associated with an unobservable variable. A study of human resource data illustrates: (1) how the usual goodness-of-fit tests, model selection and cross-validation criteria can be inconclusive; (2) how model selection and evaluation procedures from time series and economic forecasting can be applied to extend residual analysis in this context.     

Dropout from exercise programs for seniors: a prospective cohort study

This study examines dropout incidence, moment of dropout, and switching behavior in organized exercise programs for seniors in the Netherlands, as determined in a prospective cohort study (with baseline measurements at the start of the exercise program and follow-up after 6 months; N = 1,725, response rate 73%). Participants were community-living individuals 50+ who participated in different forms of organized exercise programs. The average dropout incidence was 0.15 per 6 months, which is lower than that for the general population. The dropout incidence and the timing of dropout differed substantially between the exercise programs. In total, 31% of people who dropped out of one type of exercise program switched to another type of exercise. The type of program and exercise had a strong effect on differences in this switching behavior. It is recommended that switching behavior be monitored in future studies.     

From River God to Research Grunt: Identity,Emotions, and the River Guide

Leisure identities and occupational identities are often assumed to be opposites. Drawing on two ethnographic studies, evidence is provided to illustrate how organizational contexts (or lack thereof) both interrupt and influence the social construction of identities. River running is but one activity that provides participants with opportunities to achieve a desired identity using situated emotion cues. In this study river guides are examined to highlight the negotiations they must employ as they attempt to establish a “river” identity in contexts that distinguish their work and leisure roles.     

由VFC构成ADC的高精度电量测试系统

介绍了一种由V／F变换实现模数转换（A／D）的测试系统，其中利用了多功能同步V／F转换器AD652，测试直流电压的精度高达十万分之三左右。     

Manipulated Masculinities: Agribusiness,Deskilling, and the Rise of the Businessman‐Farmer in the United States

In this study we examine how the agribusiness industry works to manipulate conventional farming masculinities in the United States to facilitate agricultural deskilling, a process that has serious implications for the future of sustainable agriculture uptake among American farmers. Through analyzing one year's worth of advertisements in three conventional farming magazines and through conducting participant observation and interviews at the second largest indoor farming show in the United States, we examine the ways in which agribusiness companies, such as chemical, seed, and farm machinery manufacturers, represent farmers and farming masculinities in their advertisements and marketing materials. We observe a shift occurring among certain agribusiness sectors away from representations of a rugged, strong, solitary farmer, who dominates nature through his manual labor, to depictions of a “businessman” farmer, who farms in collaboration with certain qualified partners (i.e., company representatives). We ultimately argue that these new representations of farming masculinity aim to more deeply entrench conventional farmers' dependence on chemical inputs and agribusiness products by promoting a process of deskilling, effectively alienating the farmer from the land.