Hydrothermal carbon release to the ocean and atmosphere from the eastern equatorial Pacific during the last glacial termination

Arguably among the most globally impactful climate changes in Earth's past million years are the glacial terminations that punctuated the Pleistocene epoch. With the acquisition and analysis of marine and continental records, including ice cores, it is now clear that the Earth's climate was responding profoundly to changes in greenhouse gases that accompanied those glacial terminations. But the ultimate forcing responsible for the greenhouse gas variability remains elusive. The oceans must play a central role in any hypothesis that attempt to explain the systematic variations in pCO2 because the Ocean is a giant carbon capacitor, regulating carbon entering and leaving the atmosphere. For a long time, geological processes that regulate fluxes of carbon to and from the oceans were thought to operate too slowly to account for any of the systematic variations in atmospheric pCO2 that accompanied glacial cycles during the Pleistocene. Here we investigate the role that Earth's hydrothermal systems had in affecting the flux of carbon to the ocean and ultimately, the atmosphere during the last glacial termination. We document late glacial and deglacial intervals of anomalously old 14C reservoir ages, large benthic-planktic foraminifera 14C age differences, and increased deposition of hydrothermal metals in marine sediments from the eastern equatorial Pacific (EEP) that indicate a significant release of hydrothermal fluids entered the ocean at the last glacial termination. The large 14C anomaly was accompanied by a ~4-fold increase in Zn/Ca in both benthic and planktic foraminifera that reflects an increase in dissolved [Zn] throughout the water column. Foraminiferal B/Ca and Li/Ca results from these sites document deglacial declines in [${{{\rm{CO}}}_{3}}^{2-}$] throughout the water column; these were accompanied by carbonate dissolution at water depths that today lie well above the calcite lysocline. Taken together, these results are strong evidence for an increased flux of hydrothermally-derived carbon through the EEP upwelling system at the last glacial termination that would have exchanged with the atmosphere and affected both Δ14C and pCO2. These data do not quantify the amount of carbon released to the atmosphere through the EEP upwelling system but indicate that geologic forcing must be incorporated into models that attempt to simulate the cyclic nature of glacial/interglacial climate variability. Importantly, these results underscore the need to put better constraints on the flux of carbon from geologic reservoirs that affect the global carbon budget.We gratefully acknowledge the support by the National Science Foundation through a grant to Stott (MG&G 1558990) and WiSE (women in science and engineering at USC) to Harazi

Analysis and modelling of muscles motion during whole body vibration

The aim of the study is to characterize the local muscles motion in individuals undergoing whole body mechanical stimulation. In this study we aim also to evaluate how subject positioning modifies vibration dumping, altering local mechanical stimulus. Vibrations were delivered to subjects by the use of a vibrating platform, while stimulation frequency was increased linearly from 15 to 60Hz. Two different subject postures were here analysed. Platform and muscles motion were monitored using tiny MEMS accelerometers; a contra lateral analysis was also presented. Muscle motion analysis revealed typical displacement trajectories: motion components were found not to be purely sinusoidal neither in phase to each other. Results also revealed a mechanical resonant-like behaviour at some muscles, similar to a second-order system response. Resonance frequencies and dumping factors depended on subject and his positioning. Proper mechanical stimulation can maximize muscle spindle solicitation, which may produce a more effective muscle activation

Perception of Vibrotactile Cues in Musical Performance

We suggest that studies on active touch psychophysics are needed to inform the design of haptic musical interfaces and better understand the relevance of haptic cues in musical performance. Following a review of the previous literature on vibrotactile perception in musical performance, two recent experiments are reported. The first experiment investigated how active finger-pressing forces affect vibration perception, finding significant effects of vibration type and force level on perceptual thresholds. Moreover, the measured thresholds were considerably lower than those reported in the literature, possibly due to the concurrent effect of large (unconstrained) finger contact areas, active pressing forces, and long-duration stimuli. The second experiment assessed the validity of these findings in a real musical context by studying the detection of vibrotactile cues at the keyboard of a grand and an upright piano. Sensitivity to key vibrations in fact not only was highest at the lower octaves and gradually decreased toward higher pitches; it was also significant for stimuli having spectral peaks of acceleration similar to those of the first experiment, i.e., below the standard sensitivity thresholds measured for sinusoidal vibrations under passive touch conditions

Abstracts from the 20th International Symposium on Signal Transduction at the Blood-Brain Barriers

https://deepblue.lib.umich.edu/bitstream/2027.42/138963/1/12987_2017_Article_71.pd

Estimation of occupational and health risk connected with exposure to hand-arm vibration

W artykule przedstawiono trzy rodzaje oceny ryzyka: ocenę zawodowego ryzyka opartego na wartościach NDN ocenę ryzyka zdrowotnego opartego na modelu matematycznym, a także ocenę ryzyka zdrowotnego weryfikowanego badaniami medycznymi.This study discusses three kinds of risk assessment: occupational risk assessment based on threshold limit values, health risk assessment based on the dose-response model and health risk assessment verified by medical examinations

New TLV values for vibration at workstations

Najwyższe dopuszczalne wartości (NDN) ogólnych oraz miejscowych drgań mechanicznych zostały przygotowane na podstawie analizy: piśmiennictwa światowego, projektów normatywów ISO, propozycji wartości NDN Komisji Unii Europejskiej i projektów opracowywanych w innych krajach. Jako wielkość normatywną drgań mechanicznych przyjęto ważoną częstotliwościowo skuteczną wartość sumy wektorowej przyspieszeń w odniesieniu do 8 godzinnego działania wibracji w ciągu zmiany roboczej. Dla ogólnych drgań mechanicznych przyjęto dopuszczalną dla 8 godzin wartość sumy wektorowej przyspieszeń wynoszącą 0,8 ms,2 i odpowiednio 3,2 m/s2 dla ekspozycji trwających 30 minut i krócej. Dla miejscowych drgań mechanicznych przyjęto dopuszczalną dla 8 godzin wartość sumy wektorowej przyspieszeń wynoszącą 2,8 m/s2 i odpowiednio 11,2 m/s2 dla ekspozycji trwających 30 minut i krócej.Threshold limit values (TLVs) for whole-body vibration and tor hand-arm vibration were prepared on the basis of an analysis of data published in literature, ISO standards, TLV drafts of the European Union and regulations used in other countries. The exposure limit for 8-hour energy equivalent frequency-weighted acceleration sum was officially accepted. The TLV for this vector sum for 8-hour exposure to whole-body vibration equals 0.8 m/s2, arid for 30-minute and shorter exposure 1 equals 3.2 m/s2. The TLV for the vector sum for 8-hour exposure to hand-arm vibrahon equals 2.8 m/s 2 , and for 30-minute and shorter exposure it equals 11.2 m/s2

Measuring Coupling Forces Woodcutters Exert on Saws in Real Working Conditions

Prolonged exposure to hand–arm vibration (HAV) generated by chainsaws can cause HAV syndrome, i.e., disorders in the upper extremities of forestry workers. Progress of HAV syndrome depends on the intensity of mechanical vibration transmitted throughout the body, which is directly proportional to coupling forces applied by the woodcutter to a vibrating tool. This study aimed to establish a method of measuring coupling forces exerted by chainsaw workers in real working conditions. Coupling forces exerted by workers with their right and left hands were measured with a hydro-electronic force meter. Wood hardness, the type of chainsaw and the kind of forest operation, i.e., felling, cross-cutting or limbing, were considered