Categorical methods in graded ring theory

Let G be a group, R a G-graded ring and X a right G-set . We study functors between categories of modules graded by G-sets, continuing the work of [M]. As an application we obtain generalizations of Cohen-Montgomery Duality Theorems by categorical methods. Then we study when some functors introduced in [M] (which generalize some functors ocurring in [D1], [D2] and [NRV]) are separable. Finally we obtain an application to the study of the weak dimension of a group graded ring

Ergonomics processes: implementation guide and tools for the mining industry

"Research has shown that an ergonomics process that identifies risk factors, devises solutions to reduce musculoskeletal disorders (MSDs), and evaluates the effectiveness of the solutions can lower worker exposure to risk factors and MSDs and improve productivity. A review of the Mine Safety and Health Administration (MSHA) injury/illness database indicated that 46% of illnesses in 2004 were associated with repetitive trauma and 35% of nonfatal lost days involved material handling during 2001- 2004. Even though these statistics show that MSDs significantly contribute to occupational illnesses and injuries in the U.S. mining industry, few mining companies have implemented an ergonomics process. Despite the many unique challenges in the mining environment, three mining companies partnered with the MSD Prevention Team at the National Institute for Occupational Safety and Health's Pittsburgh Research Laboratory to demonstrate that an ergonomics process could be systematically implemented and effectively integrated with existing safety and health programs. Because these three mining companies were very different in organization, culture, and size, the ergonomics processes had to be modified to meet the needs of each company. A description of how these three companies applied ergonomics and the tools and training used to implement their processes is given. Prior to discussing the case studies, general information on the elements of an ergonomics process is provided.' - NIOSHTIC-21. Introduction: Ergonomics and risk management -- 2. Ergonomics processes: case studies -- 3. Process effectiveness -- 4. Implementation tools -- 5. Training -- References -- Appendix: Ergonomics processes: beyond traditional safety and health programsby Janet Torma-Krajewski, Lisa J. Steiner, Robin Burgess-Limerick."February 2009."Also available via the World Wide Web.Includes bibliographical references

Prevalence of Total Tooth Loss, Dental Caries, and Periodontal Disease in Mexican-American Adults: Results from the Southwestern HHANES

The Southwestern portion of the Hispanic Health and Nutrition Examination Survey (HHANES) was conducted by the National Center for Health Statistics (NCHS) in 1982 and 1983. The survey population was Mexican-Americans residing in five Southwestern states. This report presents data on the prevalence of total tooth loss, dental caries, and periodontal diseases in 3860 Mexican-American adults aged from 18 to 74. Results show that 4.3% of this group was edentulous. Among the dentate, Mexican-Americans had lower overall DMF scores but higher numbers of untreated decayed teeth than did residents of the same region seen in the NHANES I survey in 1971-1974. Caries of the smooth surfaces in both posterior and anterior teeth was more pronounced in the older than in the younger age groups. Mexican-Americans had more gingivitis but fewer periodontal pockets than did the general population in the Western states during NHANES 1. The caries pattern in the Mexican-Americans suggests that caries among adults may remain a problem in the future, with the possibility of increased involvement with the aging, although modest, of smooth tooth surfaces.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/68143/2/10.1177_00220345870660061801.pd

The Application of major hazard risk assessment (MHRA) to eliminate multiple fatality occurrences in the U.S. minerals industry

"Major Hazard Risk Assessment (MHRA) is used to help prevent major hazards, e.g., fire, explosion, wind-blast, outbursts, spontaneous combustion, roof instability and chemical and hazardous substances, etc., from injuring miners. The structured process associated with MHRA helps to characterize the major hazards and evaluate engineering, management and work process factors that impact how a mine mitigates its highest risk. The National Institute for Occupational Safety and Health (NIOSH) studied the application of this technique to US mining conditions through a field-oriented pilot project. Risk assessment teams used in the pilot project were primarily composed of mining company personnel. Ten case studies were performed over a wide cross-section of mines. These mines were representative of the important mining commodities in the US minerals industry, i.e. coal, metal, non-metal, and aggregate. Also, the sizes of the mines ranged from small to large and were located across the country. The ten case studies demonstrate that most US mines have the capability to successfully implement an MHRA and that the MHRA methodology produced additional prevention controls and recovery measures to lessen the risk associated with a select population of major mining hazards. The basic ingredient for a successful MHRA is the desire to become more proactive in dealing with the risks associated with events that can cause multiple fatalities. A successful outcome is marked by a thorough examination of existing prevention controls and recovery measures. When pressed to consider more controls to further mitigate the risk, a well-staffed risk assessment team was able to identify additional controls. For these mining operations, it was important to add additional controls, even if they were not required by existing mining regulations, to lower the risks associated with the major hazards under consideration. If a mining operation is not willing to commit its best people to an MHRA or will not provide them with sufficient time to see the process through to its conclusion, the MHRA output may prove to be useless. Additionally, if a mining operation is not prepared to discuss its major hazards in an open and honest fashion and to present the findings of the risk assessment in a written report, the MHRA output will be unclear, and attempts to monitor or audit important controls may not be possible. A MHRA is most effective when the mining operation possesses 1) a proper understanding of its hazards, 2) experience with informal and basic-formal risk assessment techniques, 3) proper facilities, machinery and equipment, 4) suitable systems and procedures that represent industry Best Practice, 5) appropriate organizational support with adequate staff, communications and training, 6) a formal and thorough plan for emergency response, and 7) a safety risk management approach that is promoted and supported at all levels of the organization." - NIOSHTIC-2by A. Iannacchione, F. Varley and T. Brady."October 2008."Also available via the World Wide Web.Includes bibliographical references (p. 121-122)

Full-scale testing of the float dust deposition meter

"Coal dust and float coal dust, produced during normal mining operations, in underground coal mines, are carried from the point of origin downstream by the ventilating air, where it deposits on the surfaces of the mine entry. In an explosion, this dust is lifted from the surfaces by the aerodynamic disturbances and, if of sufficient quantity, can continue to propagate the explosion. To prevent the surface coal dust from contributing, it must be inerted, typically by spreading pulverized limestone, i.e., rock dust, over the coal dust surface. To facilitate the dusting operation, the National Institute for Occupational Safety and Health (NIOSH), Pittsburgh Research Laboratory (PRL), developed an automated system that continuously monitors the accumulation of coal dust. This system could activate a rock-dusting machine that disperses rock dust into the ventilation air when dangerous deposits accumulate and deactivate the machine when sufficient inert has been deposited on top of the coal dust. The system consists of a microprocessor-controlled optical float dust deposition meter. This device measures the light intensity reflected from a deposited layer of dust. A standard cap lamp is used as a fixed- position light source. From the reflected light signal, the microprocessor determines the hazard level of the deposited layer and performs the appropriate action. " - NIOSHTIC-2Robert A. Cortese and Henry E. Perlee.Also available via the World Wide Web.Includes bibliographical references

Strategies for escape and rescue from underground coal mines

"Section 2 of the Mine Improvement and New Emergency Response Act of 2006 (2006 MINER Act), Public Law 109-236, [MINER Act 2006] directed operators of underground coal mines to improve accident preparedness and response. This report summarizes the findings of research conducted by the National Institute for Occupational Safety and Health (NIOSH) between December 2007 and March 2009 to identify the attributes of an improved escape and rescue system. This report focuses on specific guidelines for escape and rescue from underground coal mines during fire and explosion incidents and contains an investigation of United States and worldwide mine practices. The basic elements of a mine emergency response system (escape, rescue, and incident command) are addressed. Further, knowledge gaps, training, human behavior, and technology challenges are also identified. This report presents a strategy of self-escape and safe-rescue including incident command as an integrated system with consideration given to U.S. underground coal mine demographics. The findings are intended to facilitate the evolution of all miners' capabilities and support institutions so that they will have a greater chance of successfully managing abnormal incidents without injury or fatalities." - NIOSHTIC-2by Danrick W. Alexander, Susan B. Bealko, Michael J. Brnich, Kathleen M. Kowalski-Trakofler, Robert H. Peters."February 2010."Available on the internet at the cdc.giv website; verified 3-17-10.Includes bibliographical references (p. 47-51

Prediction of longwall methane emissions: an evaluation of the influence of mining practices on gas emissions and methane control systems

"The primary purpose of this field study was to predict the methane emission consequences of mining longwall panels of greater face width in the Pochontas No. 3 Coalbed in Virginia. Mines were to be increased from 229 to 305 m (750 to 1,000 ft). However, since historically high methane emissions from the longwall face and gobs were already being experienced, there was a concern for further increases in methane emission rates. If preferables from a safety perspective to be prepared in advance, either with increased ventilation airflow, or with additional methane drainage. The bleeder and methane drainage systems associated with the two study panels were also evaluated to fully characterize the methane liberation patterns and control system performance for each study area. " - NIOSHTIC-2William P. Diamond and Fred Garcia."October 1999."Includes bibliographical references (p. 32)

Miner training simulator: user's guide and scripting language documentation

"A training software package for new mine employees, called Miner Training Simulator (MTS), has been developed by researchers at the National Institute for Occupational Safety and Health. MTS is a computer-based tool that allows a trainee to enter a simulated mine and interact with his/her surroundings in order to learn basic mining concepts, safety procedures, mine layouts, and escape routes. The training simulator software and instructions for its use are described in this report. Also, each mine using the software will have different requirements with regard to safety training. To customize the simulator for these differences, an interpreted scripting language is used to define interactions between the trainee and the virtual mine and objects in it. The scripting language, called Tool Command Language, uses simple commands to control various actions in the simulation, such as sounds, safety messages, hazards, and movement of objects. The basics of the scripting language are described here, along with many examples and instructions for building a script for MTS." - NIOSHTIC-2by Todd M. Ruff."June 2001."Also available via the World Wide Web.Includes bibliographical references (p. 11)

A Performance evaluation of two overhead power line proximity warning devices

"Accidental contact of overhead electrical power lines by mobile equipment is a leading cause of occupational fatalities in the United States, accounting for 20% of on-the-job electrocutions. Overhead electrical power line proximity warning devices (PWDs) are intended to warn personnel if mobile equipment moves within some preselected minimum distance of an energized overhead electrical power line. Two commercially available PWDs were tested at the National Institute for Occupational Safety and Health's (NIOSH) Pittsburgh Research Laboratory (PRL). The objective of the tests was to document performance capabilities and limitations for these PWDs by identifying factors that can influence their operation. The two PWDs evaluated in this research are the SIGALARM Model 210 marketed by Allied Safety Systems, LLC, and the ASE Model 2100 from Allied Safety Engineering. Both of these devices operate by measuring the electric field present around energized power lines. The PWDs were installed on a government-owned 22-st (20-mt) rough terrain crane. A purpose-built test site used for this research at PRL allowed operation of the crane near a variety of power line configurations operating at up to 25 kV. Most of the tests involved positioning the crane adjacent to one or more overhead power lines, adjusting sensitivities of the PWDs to alarm when the crane boom was approximately 20 ft (6.1 m) from the power lines, swinging the crane boom toward the lines under a wide variety of test conditions, and finally, for each unique set of test conditions, documenting the deviation from 20 ft (6.1 m) for actual alarm activation. Test results show that several factors can adversely affect PWD performance. PWD alarm accuracy generally deteriorated when operating with a boom position significantly different than that used for the device's last sensitivity adjustment. Another factor that can affect PWD performance is configuration of the overhead power line(s) involved. Accuracy of alarm activation distances was best for simple single-circuit installations, but degraded for multiple circuits on the same poles. This degradation was slightly greater for installations with different voltage levels and/or a combination of vertical and horizontal conductor arrangements. Performance also degraded for crane operation between two intersecting power line installations, especially for intersecting lines at different voltages. An additional aspect of power line configuration shown to influence PWD accuracy was phase sequence on the power line circuit(s). Specific phase conductor arrangements and combinations, particularly in multiple circuit installations, resulted in either improved or degraded accuracy. Tests were also conducted to evaluate the PWDs as "early warning devices" for situations such as moving a mobile crane into an unfamiliar work area. Results showed that the SIGALARM Model 210 could detect energized 13-kV power lines at a distance of 75-88 ft (22.9-26.8 m). This alarm distance would allow an operator to take preventive measures before the crane is in a position from which it could contact nearby power lines. " - NIOSHTIC-2by Gerald T. Homce, James C. Cawley, and Michael R. Yenchek."November 2008.""CDC workplace safety and health"--Cover.Also available via the World Wide Web.Includes bibliographical references (p. 36)

Nitrogen dioxide calibration standards for portable monitors

"Mine operators and Mine Safety and Health Administration inspectors use portable gas monitors in underground mines to measure worker exposure to various gases such as methane, carbon monoxide, and nitrogen dioxide (NO2). Even in relatively small concentrations, NO2 can produce harmful side effects in underground workers. Mines using equipment powered by diesel engines, carrying out explosive blasting operations, and performing extensive arc welding and/or cutting work will have measurable quantities of NO2 released by these processes. Workers in these areas often use gas monitors to warn of excessive gas concentrations and to help them determine when to increase ventilation air that will dilute these gases, thus minimizing exposures to this gas. Portable gas monitors, used to measure NO2 levels, must be calibrated before each use. Calibration is typically performed using a small portable pressurized cylinder containing a certified gas mixture. The certified NO2 standard mixture, usually 10 ppm NO2 concentration, is diluted with either air or nitrogen gas. To determine the stability of commercially available portable gas standards, two different cylinders containing NO2 in nominal 10-ppm concentrations were examined. One cylinder was diluted in air, the other, in nitrogen. Baseline NO2 mixtures were generated using a standard liquid NO2 permeation tube operated at a constant temperature. Final dilutions of the test gas mixtures were made with air or with nitrogen using a mass flow-controlled gas dilution system. This study showed that, when a permeation-type NO2 generator is used, the electrochemical sensors in portable NO2 monitors provide identical results for gas mixtures whether they are diluted with air or with nitrogen. Two different gas monitors, one with a two-electrode sensor and one with a three-electrode sensor, were used to measure gas concentrations in the two commercially available cylinders. One month after the cylinders were delivered, the NO2-in-nitrogen cylinder, stated to contain 10 ppm NO2, measured 8.13 ppm. The NO2-in-air cylinder, also stated to hold 10 ppm NO2, measured 6.88 ppm. Therefore, before using NO2 gas cylinders to calibrate monitors, it is recommended that their concentrations be verified either by manufacturer recertification or by comparing the stated cylinder gas concentrations to a laboratory-based permeation tube-generated standard. " - NIOSHTIC-2by Joseph E. Chilton, Robert J. Timko, and Edward J. Chuhta."December 2005."Also available via the World Wide Web.Includes bibliographical references (p. 8)