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Middle Levels (middle + level)
Selected AbstractsMechanical properties of femoral cortical bone following cemented hip replacementJOURNAL OF ORTHOPAEDIC RESEARCH, Issue 11 2007G.X. Ni Abstract Femoral bone remodeling following total hip replacement is a big concern and has never been examined mechanically. In this study, six goats underwent unilateral cemented hip hemiarthroplasty with polymethyl methacrylate (PMMA) bone cement. Nine months later animals were sacrificed, and the femoral cortical bone slices at different levels were analysed using microhardness testing and microcomputed tomography (micro-CT) scanning. Implanted femurs were compared to contralateral nonimplanted femurs. Extensive bone remodeling was demonstrated at both the proximal and middle levels, but not at the distal level. Compared with the nonimplanted side, significant decreases were found in the implanted femur in cortical bone area, bone mineral density, and cortical bone hardness at the proximal level, as well as in bone mineral density and bone hardness at the middle level. However, no significant difference was observed in either variable for the distal level. In addition, similar proximal-to-distal gradient changes were revealed both in cortical bone microhardness and bone mineral density. From the mechanical point of view, the results of the present study suggested that stress shielding is an important mechanical factor associated with bone adaptation following total hip replacement. © 2007 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 25:1408,1414, 2007 [source] Response Surface Designs for Experiments in BioprocessingBIOMETRICS, Issue 2 2006Steven G. Gilmour Summary Many processes in the biological industries are studied using response surface methodology. The use of biological materials, however, means that run-to-run variation is typically much greater than that in many experiments in mechanical or chemical engineering and so the designs used require greater replication. The data analysis which is performed may involve some variable selection, as well as fitting polynomial response surface models. This implies that designs should allow the parameters of the model to be estimated nearly orthogonally. A class of three-level response surface designs is introduced which allows all except the quadratic parameters to be estimated orthogonally, as well as having a number of other useful properties. These subset designs are obtained by using two-level factorial designs in subsets of the factors, with the other factors being held at their middle level. This allows their properties to be easily explored. Replacing some of the two-level designs with fractional replicates broadens the class of useful designs, especially with five or more factors, and sometimes incomplete subsets can be used. It is very simple to include a few two- and four-level factors in these designs by excluding subsets with these factors at the middle level. Subset designs can be easily modified to include factors with five or more levels by allowing a different pair of levels to be used in different subsets. [source] The spatial pattern of summertime subtropical anticyclones over Asia and Africa: A climatological reviewINTERNATIONAL JOURNAL OF CLIMATOLOGY, Issue 2 2010Azar Zarrin Abstract The National Centers for Environmental Prediction-National Center for Atmospheric Research (NCEP-NCAR) monthly mean reanalysis dataset has been used to analyze spatial variations of summertime subtropical anticyclones over the Asia,Africa region. The geopotential height and zonal wind components of 1000, 500, 200, and 100 hPa in a 30-year period (1971,2000) have been used to determine the spatial and temporal variations of the anticyclone centres, their monthly frequency and latitudinal axis variations during April,October. The results revealed that there is a clear difference in the location of the summer anticyclone centres in lower, middle and upper levels of the troposphere. In the lower levels, the Azores subtropical anticyclone is located at the east of North Atlantic. In the middle levels, the frequencies of anticyclone centre are concentrated over the northwest of Africa, Arabian Peninsula and Iranian Plateau. In the upper troposphere, the geographical location of the anticyclone centres and their frequencies in the summer season exhibit a scattered pattern from south of China up to western Iran at 200 hPa, and a bimodal pattern over the Tibetan and the Iranian Plateaus at 100 hPa. In fact, in the entire study domain, the Iranian Plateau is a preferable location of the middle and upper troposphere anticyclones. The highest observed latitude of the subtropical anticyclone at 100, 200 and 500 hPa levels have been seen over north of Tibetan plateau, a large area from east to west of Asia and Iran during August, July,August and July, respectively. The maximum monthly variation in the latitude of the ridgeline is seen at 500, 200, and 100 hPa from June to July which goes even up to 10 degrees at some longitudes. Copyright © 2009 Royal Meteorological Society [source] An analysis of late twentieth century trends in Australian rainfallINTERNATIONAL JOURNAL OF CLIMATOLOGY, Issue 6 2009Andréa S. Taschetto Abstract Trends in Australian precipitation from 1970 to 2006 are examined using a daily rainfall dataset. Results suggest a linkage between changes in the monsoon trough and rainfall trends over northwestern Australia. The late twentieth century drought observed along the Queensland coast is a response to changes in the atmospheric circulation that generates anomalous subsidence at high and middle levels of the atmosphere, thus inhibiting convection over the region. In addition, an anomalous anticyclonic circulation at low levels over Queensland tends to weaken the easterlies in the tropical western Pacific, thus diminishing the transport of moist air onto the coast. Trends in the frequency and magnitude of different rainfall events are also examined. This reveals that changes in total rainfall are dominated by trends in very heavy rainfall events across Australia. For example, some parts of western Australia reveal an increase in heavy rainfall events that are not accompanied by a rise in modest rainfall events, resulting in changes in the shape of the distribution towards a more skewed precipitation distribution. On the other hand, the frequency of extreme rainfall events along the Queensland coast has declined during summer and autumn consistently with the total rainfall decrease, indicating changes in the position of the precipitation distribution rather than its shape. Copyright © 2008 Royal Meteorological Society [source] Mechanical properties of femoral cortical bone following cemented hip replacementJOURNAL OF ORTHOPAEDIC RESEARCH, Issue 11 2007G.X. Ni Abstract Femoral bone remodeling following total hip replacement is a big concern and has never been examined mechanically. In this study, six goats underwent unilateral cemented hip hemiarthroplasty with polymethyl methacrylate (PMMA) bone cement. Nine months later animals were sacrificed, and the femoral cortical bone slices at different levels were analysed using microhardness testing and microcomputed tomography (micro-CT) scanning. Implanted femurs were compared to contralateral nonimplanted femurs. Extensive bone remodeling was demonstrated at both the proximal and middle levels, but not at the distal level. Compared with the nonimplanted side, significant decreases were found in the implanted femur in cortical bone area, bone mineral density, and cortical bone hardness at the proximal level, as well as in bone mineral density and bone hardness at the middle level. However, no significant difference was observed in either variable for the distal level. In addition, similar proximal-to-distal gradient changes were revealed both in cortical bone microhardness and bone mineral density. From the mechanical point of view, the results of the present study suggested that stress shielding is an important mechanical factor associated with bone adaptation following total hip replacement. © 2007 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 25:1408,1414, 2007 [source] Patterns of positional behavior in mixed-species troops of Callimico goeldii, Saguinus labiatus, and Saguinus fuscicollis in northwestern BrazilAMERICAN JOURNAL OF PRIMATOLOGY, Issue 1 2001P.A. Garber Abstract We present the results of a 4-month field investigation of positional behavior, vertical ranging, and species differences in limb proportions and body mass in a mixed-species troop of Saguinus fuscicollis, Saguinus labiatus, and Callimico goeldii in northwestern Brazil. Despite certain similarities in overall positional repertoire, patterns of positional behavior varied significantly between species. Travel in Callimico occurred principally in the lowest levels of the canopy, and was characterized by an exaggerated form of hindlimb-dominated bounding (bounding-hop), and leaping to and from vertical trunks (55.1% of leaps). In contrast, saddle-back tamarins traveled in the lower and middle levels of the canopy, and engaged in a range of leaping behaviors, including stationary leaps (37.3%), acrobatic leaps (31.3%), and trunk-to-trunk leaps (20%). Red-bellied tamarins exploited the highest levels of the arboreal canopy. Travel in this species was dominated by quadrupedal bounding and acrobatic leaps (67% of leaps) that began and ended on thin, flexible supports. Species differences in positional behavior correlated with species differences in limb proportions and locomotor anatomy, and provide a framework for understanding niche partitioning in mixed-species troops of Saguinus and Callimico. Am. J. Primatol. 54:17,31, 2001. © 2001 Wiley-Liss, Inc. [source] | ||||||||||