Effects of portable computing devices on posture,muscle activation levels and efficiency

Very little research exists on ergonomic exposures when using portable computing devices. This study quantified muscle activity (forearm and neck), posture (wrist, forearm and neck), and performance (gross typing speed and error rates) differences across three portable computing devices (laptop, netbook, and slate computer) and two work settings (desk and computer) during data entry tasks. Twelve participants completed test sessions on a single computer using a test–rest–test protocol (30 min of work at one work setting, 15 min of rest, 30 min of work at the other work setting). The slate computer resulted in significantly more non-neutral wrist, elbow and neck postures, particularly when working on the sofa. Performance on the slate computer was four times less than that of the other computers, though lower muscle activity levels were also found. Potential or injury or illness may be elevated when working on smaller, portable computers in non-traditional work settings.     

Utilizing linguistically enhanced keystroke dynamics to predict typist cognition and demographics

Entering information on a computer keyboard is a ubiquitous mode of expression and communication. We investigate whether typing behavior is connected to two factors: the cognitive demands of a given task and the demographic features of the typist. We utilize features based on keystroke dynamics, stylometry, and “language production”, which are novel hybrid features that capture the dynamics of a typists linguistic choices. Our study takes advantage of a large data set (~350 subjects) made up of relatively short samples (~450 characters) of free text. Experiments show that these features can recognize the cognitive demands of task that an unseen typist is engaged in, and can classify his or her demographics with better than chance accuracy. We correctly distinguish High vs. Low cognitively demanding tasks with accuracy up to 72.39%. Detection of non-native speakers of English is achieved with F₁=0.462 over a baseline of 0.166, while detection of female typists reaches F₁=0.524 over a baseline of 0.442. Recognition of left-handed typists achieves F₁=0.223 over a baseline of 0.100. Further analyses reveal that novel relationships exist between language production as manifested through typing behavior, and both cognitive and demographic factors.     

基于C#的打字测试软件研究与开发

信息时代下,掌握和熟练操作计算机成为社会对现代人的基本要求.文字录入的快慢在一定程度上影响着工作效率.开发一套较完善的打字测试软件来公平公正的考核学生的打字水平成为必要.基于C#语言开发的打字测试软件具有界面简捷、组织测试方便、评分精确合理、成绩回收容易、统计成绩方便.学生水平分析准确等优点.     

Wrist and forearm postures and motions during typing

Awkward upper extremity postures and repetitive wrist motions have been identified by some studies as risk factors for upper extremity musculoskeletal disorders during keyboard work. However, accurate body postures and joint motions of typists typing on standardized workstations are not known. A laboratory study was conducted to continuously measure wrist and forearm postures and motions of 25 subjects while they typed for 10 – 15 min at a standard computer workstation adjusted to the subjects' anthropometry. Electrogoniometers continuously recorded wrist and forearm angles. Joint angular velocities and accelerations were calculated from the postural data. The results indicate that wrist and forearm postures during typing were sustained at non-neutral angles; mean wrist extension angle was 23.4 ± 10.9 degrees on the left and 19.9 ± 8.6 degrees on the right. Mean ulnar deviation was 14.7 ± 10.1 degrees on the left and 18.6 ± 5.8 degrees on the right. More than 73% of subjects typed with the left or right wrist in greater than 15 degrees extension and more than 20% typed with the left or right wrist in greater than 20 degrees ulnar deviation. Joint angles and motions while typing on an adjusted computer workstation were not predictable based on anthropometry or typing speed and varied widely between subjects. Wrist motions are rapid and are similar in magnitude to wrist motions of industrial workers performing jobs having a high risk for developing cumulative trauma disorders. The magnitude of the dynamic components suggests that wrist joint motions may need to be evaluated as a risk factor for musculoskeletal disorders during typing.     

Effects of psychosocial and individual factors on physiological risk factors for upper extremity musculoskeletal disorders while typing

Psychosocial factors are hypothesized to contribute to work-related musculoskeletal disorder (WMSD) development, although previous research has been largely epidemiological or has focused primarily on the shoulders, back and neck. The objective of this study was to quantify the effects of mental workload and time pressure on perceived workload and physiological responses of the distal upper extremity. A total of 18 typists completed nine 5-min typing sessions representing three levels of time pressure and mental workload. Levels were manipulated by adjusting typing speed and by requiring participants to perform arithmetic tasks while typing. Outcomes were measured in muscle activation levels, wrist postures and movements, key strike force and subjective assessments of workload. In general, increased time pressure increased muscle activation, key strike force and wrist deviations; and increased mental workload increased key strike force. Mental workload and time pressure mediated physical risk factors during typing to increase WMSD risk for the distal upper extremity.     

Development of a monitoring system for keyboard users' performance

To precisely evaluate the typing performance of a VDT user, a program named KBlog was developed to record the typing activity under the Microsoft Windows operating system. This program is small and simply framed in order to avoid overloading of the operating system. Without interfering with the typing task, this program can record the time of every pressing and releasing movement of each keystroke at the millisecond level. The accuracy and reliability of KBlog was tested by comparing time intervals recorded by KBlog to time intervals of keyboard output electrical signals recorded by an oscilloscope. In the regression analysis on these two indicators, results of high correlation coefficients of almost 1.000 and intercepts within acceptable levels of around 1 ms indicated sufficient accuracy and reliability of this program. Further applications are discussed in this paper concerning both laboratory and field researches.     

关于三株新血清型菌株补充绿脓杆菌国际抗原分型系统(IATS)的建议

作者在研制绿脓杆菌(PA)国际抗原分型系统(IATS)的基础上,收集了600余株绿脓杆菌,经生物学特性鉴定,交叉凝集试验和凝集素吸收试验,筛选出 CMCC-10117、PA-87、NO.446、PA-26、PS-1135株菌株(其中 NO.446、PA-26和 PS-113 3株为同型)系 IATS 不能包括的新血清型菌株。根据其抗原特异性从中选取了3株加入 IATS 中,使 IATS 由17个血清型发展为20个血清型。以新选出的MCC-10117作为 IATS-18型,PA-87作为 IATS-19型,NO.446作为 IATS-20型,经用468株临床分离的绿脓杆菌分型考核,分型率为99.4%。     

Wrist motion in computer keyboard typing

The purpose of this study is to define how wrist motion is affected by different postures and supporting devices and to discover functional range of wrist motion for keyboard typing. The range of wrist motion (ROM) needed for fourteen experienced typists to type on a computer keyboard was measured by flexible and biaxial electrogoniometers. The most frequent wrist motion during typing was in extended and ulnarly deviated positions in both wrists. Range of wrist motion was similar in both wrists. The average ROM for keyboard typing with the typists’ own posture was about 39° in flexion/extension (FEM) and 29° in radial/ulnar deviation (RUD) in both wrists. The range of wrist motion was significantly reduced to 30° in FEM and 27° in RUD with use of either wrist or forearm supporting devices, which suggests that these devices might help to relieve fatigue, discomfort, or pain during and/or after typing. Results of this study will be of interest to clinicians and helpful to those who are professionally or nonprofessionally involved in typing.     

Prevalence of Clostridium difficile in retailed meat in the Netherlands

Recent reports indicate that a large proportion of community-acquired Clostridium difficile infections (CA-CDI) are not linked to recent antibiotic therapy, older age, significant comorbidity or previous hospitalization. Possible community sources for CA-CDI include animals and food, and therefore a surveillance study on the prevalence of C. difficile in meat was performed. Samples of different meat species were collected from the retail trade and analyzed for the presence of C. difficile using a method that included selective enrichment in C. difficile broth, subsequent alcohol shock-treatment and plating onto C. difficile selective medium. C. difficile isolates were tested for the presence of toxin genes and were typed using PCR ribotyping. Of 500 samples tested, 8 (1.6%) were positive for the presence of C. difficile: 1 from lamb (6.3%) and 7 from chicken meat (2.7%). The isolated strains belonged to PCR ribotypes different from those that are currently most frequently found in patients with CDI in the Netherlands, except for C. difficile PCR ribotype 001 which was found in one chicken meat sample. This observation suggests that other matrices than meat may serve as a source for CA-CDI.     

傅立叶变换红外光谱技术对6种致病性大肠埃希氏菌快速分型的研究

目的建立肠致病性大肠埃希氏菌(Enteropathogenic E.coli,EPEC)、肠产毒性大肠埃希氏菌(Enterotoxigenic E.coli,ETEC)、肠侵袭性大肠埃希氏菌(Enteroinvasive E.coli,EIEC)、肠黏附性大肠埃希氏菌(Enteroadhesive E.coli,EAEC)、肠出血性大肠埃希氏菌(Enterohmorrhagic E.coli,EHEC)、弥散粘附性大肠埃希氏菌(Diffusely adherent E.coli,DAEC)6种致病性大肠埃希氏菌的傅立叶变换红外光谱(Fourier transform infrared spectroscopy,FT-IR)数据库及FT-IR分型方法。方法应用FT-IR技术对6种致病性大肠埃希氏菌进行指纹图谱数据采集并对其进行基线校正、归一化等处理,应用化学计量学方法对光谱数据进行分析。结果本研究建立了6种致病性大肠埃希氏菌的FT-IR光谱数据库,实现了对6种可疑目标大肠埃希氏菌鉴定;建立了主成分分析(principal component analysis,PCA)和分级聚类分析(hierarchical cluster analysis,HCA)2种模型,成功实现了对6种致病性大肠埃希氏菌的快速分型。结论 FT-IR分析方法快速、简便、易操作,结果重现性好,是一种鉴定6种致病性大肠埃希氏菌的有效方法。