The Effects of a Reduced Force Aerial Bucket Control on Upper Extremity Muscular Demands as Assessed with Surface Electromyography

A common control for operating aerial bucket trucks for utility companies in North America is called a pistol grip control. Based upon many anecdotal reports of forearm muscle fatigue from workers using this control, Prof. Richard Marklin began an EPRI-sponsored study in 2016 using EMG to determine muscle fatigue of workers while they used the pistol grip. Muscle activity recorded by EMG is a measure of the magnitude of muscle force under controlled conditions. This study confirmed the reports of muscle fatigue in extensor digitorum communis (EDC) muscle in the right forearm. The next phase of the study was to design and build a self-contained, battery-powered replacement for the pistol grip that could reduce the required input force and therefore muscle fatigue in the EDC. This new design is called the reduced-force pistol grip. The reduced-force pistol grip was then tested in a 20-participant laboratory study using EMG to quantify the reduction in muscle fatigue of the right arm. This laboratory study showed that there was a decrease in muscle activity of the right EDC while using the reduced force (50% reduced force) pistol grip as compared to a conventional force pistol grip currently used on utility trucks. The results of the truck to line full trials, which are the most representative of actual movements of the pistol grip in the field, showed that the reduction of 50% required input force produced a meaningful reduction in muscle activity of 5.6%. EMG results provide evidence that the reduced force pistol grip decreases the risk of muscle fatigue of line workers who operate the pistol grip. EMG results also corroborate reports of muscle fatigue from utility line workers who operate the pistol grip with conventional force levels. This study was the first to quantify muscular loading of an aerial bucket pistol grip control and results of the redesigned pistol grip show promise for improving the occupational health of electric utility line workers

Applied Force and sEMG Muscle Activity Required To Operate Pistol Grip Control in an Electric Utility Aerial Bucket

Electric utility line workers report high levels of fatigue in forearm muscles when operating a conventional pistol grip control in aerial buckets. This study measured the applied force and surface electromyographic (sEMG) signals from four upper extremity muscles required to operate the pistol grip control in two tasks. The first task was movement of the pistol grip in six directions (up/down, forward/rearward, clockwise/counter-clockwise), and the second task was movement of the bucket from its resting position on the truck bed to an overhead conductor on top of a 40 ft tall pole. The force applied to the pistol grip was measured in 14 aerial bucket trucks, and sEMG activity was measured on eight apprentice line workers. The applied force required to move the pistol grip control in the six directions ranged from 12 to 15 lb. The sEMG activity in the extensor digitorum communis (EDC) forearm muscle was approximately twice as great or more than the other three muscles (flexor digitorum superficialis, triceps, and biceps). Line workers exerted 14 to 30% MVCEMG to move the pistol grip in the six directions. Average %MVCEMG of the EDC to move the bucket from the truck platform to an overhead line ranged from 26 to 30% across the four phases of the task. The sEMG findings from this study provide physiologic evidence to support the anecdotal reports of muscle fatigue from line workers after using the pistol grip control for repeated, long durations

New Pistol Grip Control for an Electric Utility Aerial Bucket Reduces Risk of Forearm Muscle Fatigue

Overhead line workers have anecdotally reported elevated levels of fatigue in forearm muscles when operating the pistol grip control that maneuvers an aerial bucket on a utility truck. Previous research with surface electromyographic (sEMG) recordings of forearm muscles corroborated these reports of muscle fatigue. A new pistol grip was designed that reduces the applied force by 50% in all directions of movement. In laboratory testing, sEMG signals were recorded from the upper extremity muscles of twenty subjects, who operated a conventional-force pistol grip and the 50% reduced-force control to move a 1/15 scale model of an aerial truck boom. The muscle that resulted in the greatest sEMG activity (extensor digitorum communis (EDC)) was the muscle that workers typically pointed to when they reported forearm muscle fatigue from using the control. The reduced-forced pistol grip decreased EDC sEMG by an average of 5.6%, compared to the conventional control, increasing the maximum endurance time by 38% according to muscle fatigue models. This study was the first to quantify muscular activity of a new aerial bucket pistol grip control and the results show promise for improving the occupational health of electric utility overhead line workers, specifically reducing muscle fatigue. Before the new design of the pistol grip can be commercialized, it must be tested in the field on actual equipment

Turicella otitidis and Corynebacterium auris: 20 years on

Turicella otitidis and Corynebacterium auris, described as new species 20 years ago, have been isolated mainly from the external ear canal and middle ear fluid. While their taxonomic position has been clearly established, their diagnosis in the routine laboratory is difficult. The question of their pathogenic potential in otitis is still open but might be elucidated better if corynebacteria are speciated more often

Leg 209 Summary: Processes in a 20-km-Thick Conductive Boundary Layer beneath the Mid-Atlantic Ridge, 14°-16°NProceedings of the Ocean Drilling Program, 209 Scientific Results

This paper provides a summary of postcruise scientific results from Ocean Drilling Program (ODP) Leg 209 available to date, building upon shipboard observations and syntheses summarized in the Leg 209 Initial Results volume. During Leg 209, 19 holes were drilled at 8 sites along the Mid-Atlantic Ridge from 14°43´ to 15°44´N, mainly in residual mantle peridotite intruded by gabbroic rocks, in order to understand the tectonic and structural processes responsible for formation of oceanic lithosphere with abundant residual peridotite exposed on the seafloor coupled with a relatively low proportion of volcanic rocks.Based on proportions of recovered lithologies, the entire area may be underlain by mantle peridotite with ~20%–40% gabbroic intrusions and impregnations. Impregnated peridotites with olivine + two pyroxenes + plagioclase + spinel that apparently formed in equilibrium probably record crystallization from primitive mid-ocean-ridge basalt at pressures of 0.5–0.6 GPa. Metamorphic equilibria record isobaric cooling to ~1100°C at this pressure. Thus, the conductively cooled thermal boundary layer beneath the Mid-Atlantic Ridge in this region is >15 km thick.Combined crystallization and reaction with residual peridotite formed a series of impregnated peridotites recording increasing Na content at nearly constant Mg#; this process could explain some of the variation in fractionation-corrected Na (e.g., Na = 8.0) observed in mid-ocean-ridge basalts. Clinopyroxene textures and compositions record such impregnation processes, and they are particularly well documented for Site 1274. Other Leg 209 gabbroic rocks formed from extensive crystallization of highly evolved melts, indicating that a substantial proportion of melt entering the thermal boundary layer crystallizes entirely beneath the seafloor, with no volcanic equivalent.Alteration of peridotites occurred over a range of temperatures and is the result of three distinct processes: rock-dominated serpentinization with formation of brucite in olivine-rich lithologies, fluid-dominated serpentinization with formation of magnetite and no brucite, and fluid-dominated talc alteration with addition of SiO2 as well as H2O and oxygen. The latter two processes also exhibit detectable trace element metasomatism that is distinct in its character from the igneous impregnation described in the previous paragraph.Microstructures show that most residual peridotites were not ductilely deformed at temperatures less than ~1200°C. Structural and paleomagnetic data require tectonic rotations of relatively undeformed blocks; some rotations probably exceeded 60° around nearly horizontal axes parallel to the rift axis. Rotations occurred along several generations of high-temperature mylonitic shear zones extending deeper than 15 km depth and numerous faults at lower temperature. Early formed shear zones and faults were passively rotated around later features; such a process could have produced low-angle fault surfaces without slip on low-angle faults. This region provides end-member examples of processes that are common at many or most slow-spreading ridges.Osmium isotope ratios indicate an ancient history of depletion for residual peridotites from the 14°–16°N region along the Mid-Atlantic Ridge. Though depleted Os isotope ratios in peridotite have been reported elsewhere along the global ridge system, the values from this region are among the most depleted. In general, Os isotope ratios from mid-ocean-ridge basalts are systematically more radiogenic than Os isotope ratios from ridge peridotite samples, suggesting a polygenetic heterogeneous source for mid-ocean-ridge basalts.Geochemical studies of zircons from Leg 209 gabbroic rocks and impregnated peridotites, together with other ridge and arc-related zircons, indicate that ridge zircons have systematically lower fractionation-corrected U and Th concentrations compared to arc zircons. This observation provides a tool for interpreting the tectonic provenance of ancient detrital zircons and indicates an arclike provenance for Hadean detrital zircons.Geobiological studies and aerobiological studies were also undertaken during Leg 209. The geobiological work found no measurable microbial enhancement of olivine dissolution rate, possibly because the samples from Leg 209 were sterile. The aerobiological study determined that dust from North Africa, collected from the derrick of the JOIDES Resolution during Leg 209, contains a variety of abundant microorganisms

Proceedings of the Ocean Drilling Program, Initial Reports, Volume 209, Drilling mantle peridotite along the Mid-Atlantic Ridge from 14 degrees to 16 degrees N, Sites 1269-1275

Leg 209 was devoted to drilling mantle peridotites and associatedgabbroic rocks along the Mid-Atlantic Ridge from 14° to 16°N. This area was identified at the 1996 Workshop on Oceanic Lithosphere and Scientific Drilling into the 21st Century (OL Workshop) as the ideal region for drilling of a strike line of short holes to sample the upper mantle in a “magma-starved” portion of a slow-spreading ridge (spreading rate = ~25 km/m.y.). In this area, igneous crust is locally absent and the structureand composition of the mantle can be determined at sites morethan ~100 km apart along strike.A central paradigm of Ridge Interdisciplinary Global Experiments(RIDGE) studies is the hypothesis that mantle flow, or melt extraction, or both, are focused in three dimensions toward the centers of magmatic ridge segments, at least at slow-spreading ridges such as the Mid- Atlantic Ridge. This hypothesis has essentially reached the status of accepted theory, but it has never been subject to a direct test. A strike line of oriented mantle peridotite samples extending for a significant distancewithin magmatic segments offers the possibility of directly testingthis hypothesis. Continued dredging and submersible studies cannot provide the spatial information required to make such a test.The primary aim of drilling was to characterize the spatial variation of mantle deformation patterns, residual peridotite composition, melt migration features, plutonic rocks, and hydrothermal alteration along axis. Hypotheses for focused solid or liquid upwelling beneath ridge segments make specific predictions regarding the spatial variation of mantle lineation or the distribution of melt migration features. These predictions were directly tested by drilling. We discovered that penetrativemantle deformation fabrics are weak at every site where mantle peridotite was sampled from 14°43′N to 15°39′N. Instead, at all of these sites, deformation was localized along high-temperature shear zones and later brittle faults. Intact blocks of peridotite with high-temperature, protogranular fabrics were preserved between these zones of localized deformation and underwent substantial tectonic rotation, perhaps as much as 90° around horizontal, ridge-parallel rotation axes in some places.At most sites, drilling recovered substantial proportions of gabbroic rocks intrusive into mantle peridotite. Some of these rocks have mineral assemblages that are probably indicative of crystallization at depths of 12–20 km beneath the Mid-Atlantic Ridge. Localized deformation at several of these sites occurred preferentially within contact zones between peridotite and these gabbroic intrusions. Abundant gabbroic intrusions were found close to the 15°20' Fracture Zone, at Site 1271, and far from the fracture zone at Sites 1270, 1268, and 1275. Conversely, some holes intersected very little gabbroic material; these were at Site 1272, very close to the fracture zone, and Site 1274, far from the fracture zone. Thus, there is little evidence from the results of this leg for focusing of melt distribution away from the fracture zone and toward the centers of volcanically active ridge segments

ODP Leg 209 drills into mantle peridotite along the mid-Atlantic ridge from 14°N to 16°N

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Thrombotic and hemorrhagic complications of COVID-19 in adults hospitalized in high-income countries compared with those in adults hospitalized in low- and middle-income countries in an international registry

Background: COVID-19 has been associated with a broad range of thromboembolic, ischemic, and hemorrhagic complications (coagulopathy complications). Most studies have focused on patients with severe disease from high-income countries (HICs). Objectives: The main aims were to compare the frequency of coagulopathy complications in developing countries (low- and middle-income countries [LMICs]) with those in HICs, delineate the frequency across a range of treatment levels, and determine associations with in-hospital mortality. Methods: Adult patients enrolled in an observational, multinational registry, the International Severe Acute Respiratory and Emerging Infections COVID-19 study, between January 1, 2020, and September 15, 2021, met inclusion criteria, including admission to a hospital for laboratory-confirmed, acute COVID-19 and data on complications and survival. The advanced-treatment cohort received care, such as admission to the intensive care unit, mechanical ventilation, or inotropes or vasopressors; the basic-treatment cohort did not receive any of these interventions. Results: The study population included 495,682 patients from 52 countries, with 63% from LMICs and 85% in the basic treatment cohort. The frequency of coagulopathy complications was higher in HICs (0.76%-3.4%) than in LMICs (0.09%-1.22%). Complications were more frequent in the advanced-treatment cohort than in the basic-treatment cohort. Coagulopathy complications were associated with increased in-hospital mortality (odds ratio, 1.58; 95% CI, 1.52-1.64). The increased mortality associated with these complications was higher in LMICs (58.5%) than in HICs (35.4%). After controlling for coagulopathy complications, treatment intensity, and multiple other factors, the mortality was higher among patients in LMICs than among patients in HICs (odds ratio, 1.45; 95% CI, 1.39-1.51). Conclusion: In a large, international registry of patients hospitalized for COVID-19, coagulopathy complications were more frequent in HICs than in LMICs (developing countries). Increased mortality associated with coagulopathy complications was of a greater magnitude among patients in LMICs. Additional research is needed regarding timely diagnosis of and intervention for coagulation derangements associated with COVID-19, particularly for limited-resource settings