Self-paced hard work comparing men and women

Six fit male subjects (23 years, 171 cm, 67 kg, maximal V?O₂ = 2.25mmol kg^?1 min^?1 (50.3ml kg^?1min^?1)) and six fit female subjects (22 years, 163 cm, 57 kg, maximal V?O₂= l.83mmol kg^?1 min^?1(41.1 mlkg^?1 min^?1)) performed self-paced hard work while walking over four different terrains carrying no external load, 10 kg and 20 kg. Time on each course for individual subjects was used to determine speed and energy expenditure; heart rate was recorded as each subject completed each course. Walking speed and energy expenditure of the males were found to be significantly greater (p< 005) than those of the females overall terrains (blacktop road, 1.6 km; dirt road, 1.8 km; light brush, 1.4 km; and heavy brush, 1.3 km) and for each load carriage condition. Relative energy expenditures of the males and females for all conditions were very similar(p>0.05) and remarkably constant at a value close to 45% V?O₂max, These data indicate that the voluntary hard work rate is dependent upon maximal aerobic power. The best predictor of speed for self-paced hard work of males and females for 1 to 2 hours in duration appears to be based on 45% of maximal aerobic power.     

Why security testing is hard

Software testing fairly readily detects a program's failure to do what it is designed to do, but does not detect all of the other things that it may do in the process. Some of these may compromise security. The article discusses the development of methods and software tools to deal with these bugs.     

Improving known solutions is hard

In this paper, we study the complexity of computing better solutions to optimization problems given other solutions. We use a model of computation suitable for this purpose, the counterexample computation model. We first prove that, if PH _P ³ , polynomial time transducers cannot compute optimal solutions for many problems, even givenn ^1– non-trivial solutions, for any >0. These results are then used to establish sharp lower bounds for several problems in the counterexample model. We extend the model by defining probabilistic counterexample computations and show that our results hold even in the presence of randomness.     

Higher mental stimulation at work is associated with improved cognitive functioning in both young and older workers

The study examined whether mental stimulation received in the workplace positively affects cognitive functioning and rate of cognitive change. Data taken from the VISAT (ageing, health and work) longitudinal study concerned 3237 workers who were seen three times (in 1996, 2001 and 2006) and who were aged between 32 and 62 years at baseline. Measures of cognitive stimulation both at work and outside work were available at baseline. Cognitive efficiency was assessed on the three occasions through episodic verbal memory, attention and processing speed tests. Greater cognitive stimulation (at work and outside work) was associated with higher levels of cognitive functioning and a more favourable change over the 10-year follow-up. These results were obtained after adjustment for age, education, sex and a variety of medical, physical and psychosocial confounders. The study thus supports the hypothesis that exposure to jobs that are mentally demanding and that offer learning opportunities increases the level of cognitive functioning and possibly attenuates age-related decline. STATEMENT OF RELEVANCE: The effect of occupational activity on cognitive functioning is under-researched. This paper reports results from a substantive longitudinal study, with findings indicating that exposure to jobs that are mentally demanding are beneficial in increasing levels of cognitive functioning and possibly attenuating age-related decline.     

Physical fitness and mental performance during and after work

Two groups of subjects who differed in physical fitness (24 well-trained and 24 less well-trained male students) participated in an experiment concerned with mental performance during and after physical work. The physical work was matched between the groups in terms of the percentage of maximal work capacity. Three mental tasks were used: task I involved high information load, placing great demands on continuous concentration and switching of attention as well as on short-term memory; task 2 involved paired associate learning with recall following short and long retention delays; task 3 was a multiplication task with great demands on concentration and on short-term memory. Tasks 1 and 2 were performed during the four different work-load conditions and task 3 after the physical work. As expected, heart rate during physical work was about the same in both groups. No intergroup difference was found in mental performance during physical work. However, recovery rate in terms of heart rate was faster, and mental performance after physical work was significantly better in the fit group than in the unfit group. The results indicate that, even though physical work loads were matched between the groups to make subjective effort equal, the fit subjects were more able to resist the negative after-effects of physical effort.     

Higher mental stimulation at work is associated with improved cognitive functioning in both young and older workers

The study examined whether mental stimulation received in the workplace positively affects cognitive functioning and rate of cognitive change. Data taken from the VISAT (ageing, health and work) longitudinal study concerned 3237 workers who were seen three times (in 1996, 2001 and 2006) and who were aged between 32 and 62 years at baseline. Measures of cognitive stimulation both at work and outside work were available at baseline. Cognitive efficiency was assessed on the three occasions through episodic verbal memory, attention and processing speed tests. Greater cognitive stimulation (at work and outside work) was associated with higher levels of cognitive functioning and a more favourable change over the 10-year follow-up. These results were obtained after adjustment for age, education, sex and a variety of medical, physical and psychosocial confounders. The study thus supports the hypothesis that exposure to jobs that are mentally demanding and that offer learning opportunities increases the level of cognitive functioning and possibly attenuates age-related decline.

Statement of Relevance: The effect of occupational activity on cognitive functioning is under-researched. This paper reports results from a substantive longitudinal study, with findings indicating that exposure to jobs that are mentally demanding are beneficial in increasing levels of cognitive functioning and possibly attenuating age-related decline.     

Psychosocial work environment and mental health among construction workers

We assessed psychosocial work environment, the prevalence of mental health complaints and the association between these two among bricklayers and construction supervisors. For this cross-sectional study a total of 1500 bricklayers and supervisors were selected. Psychosocial work characteristics were measured using the Dutch Questionnaire on the Experience and Evaluation of Work and compared to the general Dutch working population. Mental health effects were measured with scales to assess fatigue during work, need for recovery after work, symptoms of distress, depression and post-traumatic stress disorder. The prevalence of self-reported mental health complaints was determined using the cut-off values. Associations between psychosocial work characteristics and self-reported mental health complaints were analysed using logistic regression.     

敏捷外包的14条原则

突如其来的金融海啸,使得全球的软件外包产业不得不重新洗牌;这对中国的软件外包企业可以算是千载难逢的机会。本文提出的基于敏捷的软件外包原则,希望能够给我们的软件人一些建议和思考。     

Why is science hard to learn?

Abstract This paper argues that science's reputation as a 'hard' subject can be attributed to four intrinsic features of science and/or learners: that science knowledge provides, for many learners, insufficient 'pay off' for the effort involved in understanding; that learning science involves reconstructions of meaning; that the tension between science as consensually agreed knowledge and science as enquiry is confusing and eventually alienating for many learners; and because science is abstract. The reasons for a link between abstraction and difficulty are briefly explored. It is suggested that certain extrinsic features of science education, resulting from choices by science educators, exacerbate these intrinsic difficulties.     

Training a single sigmoidal neuron is hard

We first present a brief survey of hardness results for training feedforward neural networks. These results are then completed by the proof that the simplest architecture containing only a single neuron that applies a sigmoidal activation function sigma: kappa --> [alpha, beta], satisfying certain natural axioms (e.g., the standard (logistic) sigmoid or saturated-linear function), to the weighted sum of n inputs is hard to train. In particular, the problem of finding the weights of such a unit that minimize the quadratic training error within (beta - alpha)(2) or its average (over a training set) within 5(beta - alpha)(2)/ (12n) of its infimum proves to be NP-hard. Hence, the well-known backpropagation learning algorithm appears not to be efficient even for one neuron, which has negative consequences in constructive learning.     

Railway-controller-perceived mental work load,cognitive failure and risky commuting

This questionnaire study tests cognitive failures as a mediator of the potential influence of mental work demands and conscientiousness on risky commuting. Participants were 104 railway-controllers (19% female). Failure of memory, attention regulation and action execution were assessed with the Workplace Cognitive Failure (WCF) scale. Mental work demands were measured by the Instrument for Stress-Oriented Task Analysis (ISTA). A structural equation model testing WCF as the mediator of (1) the relationship between mental work demands and risky commuting (p < 0.05) and (2) the link between conscientiousness and risky commuting (p < 0.05) fitted well with empirical data. In railway-controllers frequent interruptions, time pressure, and high concentration demands are likely to increase cognitive load and thereby boost WCF during work and also during commuting, thereby reducing commuting safety. The results underline the need for work redesign to improve commuting safety.

Practitioner Summary: Commuting accidents occur frequently and at high cost. This study shows that mental work demands of railway staff are related to cognitive failure and risky commuting behaviour such as failing to give way and overlooking stop signs. Primary prevention of commuting accidents should include reduction of mental workload.     

Why is technology transfer so hard?

If you were the vice president of software in a company with 10,000 software personnel, what would you do to make sure your software team had state-of-the-art tools and methodologies? At a more fundamental level, how would you and your staff even find out what they are and whether your current tools and methodologies are good, bad, or average? That is the crux of two major challenges to the software community: How do we evaluate tools and methods for effectiveness? How do we deploy better tools and methods once they have been identified? Unfortunately, the software industry lacks standard measurements and benchmarks for evaluating the effectiveness of programming tools and languages, design approaches, or almost any other kind of technology. Purchasing and acquisition decisions are often made on the basis of unsubstantiated vendor claims. Moreover, once a new tool or methodology is acquired, deployment is often slow. Tools are acquired without considering training needs, or if training is considered, it's not readily available due to schedule pressures     

Mutilated chessboard problem is exponentially hard for resolution

Mutilated chessboard principle CB_n says that it is impossible to cover by domino tiles the chessboard 2n×2n with two diagonally opposite corners removed. We prove lower bound on the size of minimal resolution refutation of CB_n.