This study investigated the location of the axis of rotation in sagittal plane movement of the spine in a free sitting condition to adjust the kinematics of a mobile seat for a dynamic chair.
Dynamic ...office chairs are designed to avoid continuous isometric muscle activity, and to facilitate increased mobility of the back during sitting. However, these chairs incorporate increased upper body movement which could distract office workers from the performance of their tasks. A chair with an axis of rotation above the seat would facilitate a stable upper back during movements of the lower back. The selection of a natural kinematic pattern is of high importance in order to match the properties of the spine.
Twenty-one participants performed four cycles of flexion and extension of the spine during an upper arm hang on parallel bars. The location of the axis of rotation relative to the seat was estimated using infrared cameras and reflective skin markers.
The median axis of rotation across all participants was located 36 cm above the seat for the complete movement and 39 cm for both the flexion and extension phases, each with an interquartile range of 20 cm.
There was no significant effect of the movement direction on the location of the axis of rotation and only a weak, non-significant correlation between body height and the location of the axis of rotation. Individual movement patterns explained the majority of the variance.
The axis of rotation for a spinal flexion/extension movement is located above the seat. The recommended radius for a guide rail of a mobile seat is between 36 cm and 39 cm.
•This study investigated the location of the axis of rotation in sagittal plane movement of the spine during the development of a new dynamic office chair design.•The average axis of rotation is independent of movement direction and located between 36 cm and 39 cm above the seat.•A novel dynamic chair containing this axis of rotation is currently developed.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
The effect of acute increase in temperature on oxygen partial pressure (Po2) was measured in the gill arches of Atlantic cod Gadus morhua between 10 and 19° C by use of oxygen microoptodes. Oxygen ...saturation of the gill blood under control conditions varied between 90 and 15% reflecting a variable percentage of arterial or venous blood in accordance with the position of each optode in the gill arch. The data obtained suggested that arterial Po2 remained more or less constant and arterial oxygen uptake did not become limiting during warming. A progressive drop in venous Po2, however, was observed at >10° C indicating that excessive oxygen uptake from the blood is not fully compensated for by circulatory performance, until finally, Po2 levels fully collapse. In a second set of experiments energy and acid–base status of white muscle of Atlantic cod in vivo was measured by magnetic resonance (31P‐NMR) spectroscopy in unanaesthetized and unimmobilized fish in the temperature range between 13 and 21° C. A decrease in white muscle intracellular pH (pHi) with temperature occurred between 10 and 16° C (ΔpH per ° C = −0·025 per ° C). In white muscle temperature changes had no influence on high‐energy phosphates such as phosphocreatine (PCr) or ATP except during exposure to high critical temperatures (>16° C), indicating that white muscle energy status appears to be relatively insensitive to thermal stress if compared to the thermal sensitivity of the whole animal. The data were consistent with the hypothesis of an oxygen limitation of thermal tolerance in animals, which is set by limited capacity of oxygen supply mechanisms. In the case of Atlantic cod circulatory rather than ventilatory performance may be the first process to cause oxygen deficiency during heat stress.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
The Anthropology of Learning in Childhood offers a large, mural-like portrait of childhood across time, culture, species, and environment. Even a casual reading of the literature on childhood will ...persuade one that learning is a very important topic that commands the attention of tens of thousands of scholars and practitioners. Yet, anthropological research on children has exerted relatively little influence on this community. This book will change that. The book demonstrates that anthropologists studying childhood can offer a description and theoretically sophisticated account of children's learning and its role in their development, socialization, and enculturation. Further, it demonstrates the particular contribution that children's learning makes to the construction of society and culture as well as the role that culture-acquiring children play in human evolution. Chapters have been contributed in archaeology, primatology, biological and cultural anthropology, and cross-cultural psychology.
A rapid method for efficiently generating site-directed mutations on a clean sequence background is described. This modification of the megaprimer PCR mutagenesis approach can be performed in one ...tube in less than 4.5 hours, and does not require purification of intermediate products. High fidelity of DNA sequence replication is obtained by employing Pfu DNA polymerase and limiting the total number of amplification cycles to 30. The mutagenesis efficiency of the procedure is high enough to allow rapid, direct identification of mutants by restriction digest or sequencing techniques.
The iron oxide magnetite, Fe
O
, is a promising conversion type lithium ion battery anode material due to its high natural abundance, low cost and high theoretical capacity. While the close packing ...of ions in the inverse spinel structure of Fe
O
enables high energy density, it also limits the kinetics of lithium ion diffusion in the material. Nanosizing of Fe
O
to reduce the diffusion path length is an effective strategy for overcoming this issue and results in improved rate capability. However, the impact of nanosizing on the multiple structural transformations that occur during the electrochemical (de)lithiation reaction in Fe
O
is poorly understood. In this study, the influence of crystallite size on the lithiation-conversion mechanisms in Fe
O
is investigated using complementary X-ray techniques along with transmission electron microscopy (TEM) and continuum level simulations on electrodes of two different Fe
O
crystallite sizes. In situ X-ray diffraction (XRD) measurements were utilized to track the changes to the crystalline phases during (de)lithiation. X-ray absorption spectroscopy (XAS) measurements at multiple points during the (de)lithiation processes provided local electronic and atomic structural information. Tracking the crystalline and nanocrystalline phases during the first (de)lithiation provides experimental evidence that (1) the lithiation mechanism is non-uniform and dependent on crystallite size, where increased Li
diffusion length in larger crystals results in conversion to Fe
metal while insertion of Li
into spinel-Fe
O
is still occurring, and (2) the disorder and size of the Fe metal domains formed when either material is fully lithiated impacts the homogeneity of the FeO phase formed during the subsequent delithiation.
Four techniques were evaluated to sample windblown splash from canker-infected citrus plants. Two volumetric cyclone samplers (PAS450 and Burkard Cyclone) and two passive samplers (funnels and ...panels) were evaluated. The PAS450 collected no detectable bacteria in any trial. The Burkard cyclone consistently collected spray, but was found to do so even when the power was turned off. Thus, the Burkard cyclone essentially functioned passively, negating the advantage of a volumetric sampler for this application. Panels collected the greatest volume of splash followed by funnel samplers. CFU of Xanthomonas axonopodis pv. citri per ml collected were significantly different between Burkards and panel samplers, but panels and funnels collected similar concentrations (Burkards, funnels, and panels collected 1,182, 1,426, and 2,667 CFU per ml, respectively). Positive correlations were found between the volume and the total X. axonopodis pv. citri collected, and between CFU per ml and total collected for panel and funnel samples. However, there was no correlation between CFU per ml and volume collected for either sampler. The Burkard sample showed a strong positive correlation (P < 0.01) between volume collected, total number of X. axonopodis pv. citri collected, and CFU per ml. The CFU per ml collected by the panels and funnels were similar (coefficient of determination, R2 = 0.97), compared with the relationship between the Burkard and panel catches (R2 = 0.68), or between the Burkard and funnel catches (R2 = 0.62). Panels collected the greatest volume, and effectively collected bacteria-laden windblown splash. The greater sampling area of the panels allowed a more representative sample than the other methods tested.
Lung cancer is the leading cause of cancer mortality worldwide. There have been only slight improvements in early diagnosis and survival, reflecting limited advances in screening and treatment for ...lung cancer. The identification of host differences in susceptibility to lung carcinogens, in particular to cigarette smoke, is essential in predicting who is at highest risk. Susceptibility differences in the form of rare, high-penetrance genes are suggested from studies of familial aggregation of lung cancer and a linkage study. Studies focused on more common, low-penetrance genes in the tobacco smoke metabolism pathways (phase I and phase II enzymes) and DNA repair pathways are reviewed, as are inflammation and cell cycle-related genes and DNA adducts as intermediate biomarkers. Also reviewed are studies of epigenetic mechanisms, such as methylation, as alternative sources of variation in host susceptibility. Studies of molecular epidemiology in lung cancer survival are discussed briefly. In the future, studies that focus on complex interactions between multiple genes and environmental exposures within pertinent pathways are needed. New technological advances in genotyping will help move the field forward.
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