The growing investment by governments and electric utilities in energy efficiency programs highlights the need for simple tools to help assess and explain the size of the potential resource.One technique that is commonly used in this effort is to characterize electricity savings in terms of avoided power plants, because it is easier for people to visualize a power plant than it is to understand an abstraction such as billions of kilowatt-hours.Unfortunately, there is no standardization around the characteristics of such power plants.In this letter we define parameters for a standard avoided power plant that have physical meaning and intuitive plausibility, for use in back-of-the-envelope calculations.For the prototypical plant this article settles on a 500 MW existing coal plant operating at a 70% capacity factor with 7% T&D losses.Displacing such a plant for one year would save 3 billion kWh/year at the meter and reduce emissions by 3 million metric tons of CO 2 per year.The proposed name for this metric is the Rosenfeld, in keeping with the tradition among scientists of naming units in honor of the person most responsible for the discovery and widespread adoption of the underlying scientific principle in question-Dr Arthur H Rosenfeld.
The investigation of serious injury and fatal accidents in the mining industry is mandated by 30 CFR 50 under the Federal Mine Safety and Health Act of 1977. The information derived from investigations can be put to important use in formulating training programs. Analysis of accident reports can result in information that points out contributing factors to accidents which not only can be modified or eliminated via administrative and/or design controls, but which can be addressed through training. This paper describes the use of accident reports to determine the relative necessity for development of training programs for mobile mining equipment operators.
Gait rehabilitation following incomplete spinal cord injury (iSCI) often aims to enhance speed and stability. Concurrently increasing both may be difficult though as certain stabilization strategies will be compromised at faster speeds. To evaluate the interaction between speed and lateral stability, we examined individuals with ( n = 12) and without ( n = 12) iSCI as they performed straight walking and lateral maneuvers at Preferred and Fast treadmill speeds. To better detect the effects of speed on stability, we challenged lateral stability with a movement amplification force field. The Amplification field, created by a cable-driven robot, applied lateral forces to the pelvis that were proportional to the real-time lateral center of mass (COM) velocity. While we expected individuals to maintain stability during straight walking at the Fast speed in normal conditions, we hypothesized that both groups would be less stable in the Amplification field at the Fast speed compared to the Preferred. However, we found no effects of speed or the interaction between speed and field on straight-walking stability [Lyapunov exponent or lateral margin of stability (MOS)]. Across all trials at the Fast speed compared to the Preferred, there was greater step width variability ( p = 0.031) and a stronger correlation between lateral COM state at midstance and the subsequent lateral foot placement. These observations suggest that increased stepping variability at faster speeds may be beneficial for COM control. We hypothesized that during lateral maneuvers in the Amplification field, MOS on the Initiation and Termination steps would be smaller at the Fast speed than at the Preferred. We found no effect of speed on the Initiation step MOS within either field ( p > 0.350) or group ( p > 0.200). The Termination step MOS decreased at the Fast speed within the group without iSCI ( p < 0.001), indicating a trade-off between lateral stability and forward walking speed. Unexpectedly, participants took more steps and time to complete maneuvers at the Fast treadmill speed in the Amplification field. This strategy prioritizing stability over speed was especially evident in the group with iSCI. Overall, individuals with iSCI were able to maintain lateral stability when walking fast in balance-challenging conditions but may have employed more cautious maneuver strategies.
A longstanding anxiety management service was redeveloped from a traditional weekly group format into a three-stage approach. The aim was to offer more patient choice, diversity, improve attendance, provide an effective use of clinician time and manage waiting lists. The development of the service is discussed alongside outcome, evaluation and experiences over a four-year period.
Background Common locomotor deficits observed in people poststroke include decreased speeds and abnormal kinematics, characterized by altered symmetry, reduced sagittal-plane joint excursions, and use of compensatory frontal-plane behaviors during the swing phase of gait. Conventional interventions utilized to mitigate these deficits often incorporate low-intensity, impairment-based or functional exercises focused on normalizing kinematics, although the efficacy of these strategies is unclear. Conversely, higher-intensity training protocols that provide only stepping practice and do not focus on kinematics have demonstrated gains in walking function, although minimal attention toward gait quality may be concerning and has not been assessed.
Objective The present study evaluated changes in spatiotemporal and joint kinematics following experimental, high-intensity stepping training compared with conventional interventions.
Design Kinematic data were combined from a randomized controlled trial comparing experimental and conventional training and from a pilot experimental training study.
Methods Individuals with gait deficits 1 to 6 months poststroke received up to 40 sessions of either high-intensity stepping training in variable contexts or conventional lower-intensity interventions. Analyses focused on kinematic changes during graded treadmill testing before and following training.
Results Significant improvements in speed, symmetry, and selected sagittal-plane kinematics favored experimental training over conventional training, although increases in compensatory strategies also were observed. Changes in many kinematic patterns were correlated with speed changes, and increased compensatory behaviors were associated with both stride length gains and baseline impairments.
Limitations Limitations include a small sample size and use of multiple statistical comparisons.
Conclusions Improved speeds and selected kinematics were observed following high-intensity training, although such training also resulted in increased use of compensatory strategies. Future studies should explore the consequences of utilizing these compensatory strategies despite the observed functional gains.
2078 Exercise-induced oxidative stress has been studied extensively however, physical inactivity via immobilization and/or hypokinetic behavior have also been associated with both general and oxidative stress. PURPOSE: The purpose of this study was to compare markers of stress (general, oxidative, and endothelial) in rats that had different access to physical activity over approximately 75% of their maximum life span potential. METHODS: 72 male Sprague-Dawley rats were randomly separated into three groups: 1) sedentary, 2) twice weekly physical activity, and 3) regular voluntary wheel running. At age 16 months, half the animals in each group were sacrificed at rest and the other half after swimming to exhaustion. Blood levels of total nitrite, prolactin, and intercellular adhesion molecule (I-CAM) were measured. RESULTS: Acute exercise resulted in higher levels of prolactin (general stress) and total nitrite (oxidative stress). Mean resting prolactin levels were lowest in the wheel running group (4.18+0.61 vs. 6.17 + 0.95 ng/ml in the activity group and 9.9 + 2.38 ng/ml in the sedentary group, p <0.05). Following exercise, prolactin levels increased 136%, 141%, and 50% in the running, activity group and sedentary group, respectively. Resting total nitrite did not differ among the three groups. Exercise resulted in an average 350% increase (p<0.05) in total nitrite for all groups with no differences among the groups: sedentary = 138+21mM, activity box = 116+22 mM, and running group:111+ 34 mM. Resting I-CAM was highest in the sedentary group (21656+3750 vs. 14075+1191 activity box and 19331+1933+1370 mU/ml in the running group) and decreased following exercise only in the sedentary group (p<0.05). CONCLUSION: Animals with access to a running wheel demonstrated the lowest resting stress levels (low prolactin) and animals with no access to physical activity had the highest endothelial stress levels (I-CAM levels). Oxidative stress as measured by total nitrites, was less affected by access to physical activity. Supported by NIH Grant 1 R15 AG 20526–01A1.
Abstract Background Common locomotor deficits observed in people poststroke include decreased speeds and abnormal kinematics, characterized by altered symmetry, reduced sagittal-plane joint excursions, and use of compensatory frontal-plane behaviors during the swing phase of gait. Conventional interventions utilized to mitigate these deficits often incorporate low-intensity, impairment-based or functional exercises focused on normalizing kinematics, although the efficacy of these strategies is unclear. Conversely, higher-intensity training protocols that provide only stepping practice and do not focus on kinematics have demonstrated gains in walking function, although minimal attention toward gait quality may be concerning and has not been assessed. Objective The present study evaluated changes in spatiotemporal and joint kinematics following experimental, high-intensity stepping training compared with conventional interventions. Design Kinematic data were combined from a randomized controlled trial comparing experimental and conventional training and from a pilot experimental training study. Methods Individuals with gait deficits 1 to 6 months poststroke received up to 40 sessions of either high-intensity stepping training in variable contexts or conventional lower-intensity interventions. Analyses focused on kinematic changes during graded treadmill testing before and following training. Results Significant improvements in speed, symmetry, and selected sagittal-plane kinematics favored experimental training over conventional training, although increases in compensatory strategies also were observed. Changes in many kinematic patterns were correlated with speed changes, and increased compensatory behaviors were associated with both stride length gains and baseline impairments. Limitations Limitations include a small sample size and use of multiple statistical comparisons. Conclusions Improved speeds and selected kinematics were observed following high-intensity training, although such training also resulted in increased use of compensatory strategies. Future studies should explore the consequences of utilizing these compensatory strategies despite the observed functional gains.
