922 resultados para Upper limbs
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http://www.archive.org/details/missionarypionee00stewrich
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The purpose of this study is to explore aspects of social organisation during the Upper Palaeolithic and Mesolithic periods using craniometric data. Different hypotheses were tested using geometric morphometrics, alongside traditional craniometric data. The clustering of individuals from the same site, as well as a correspondence to an isolation-by-distance model—particular in the Mesolithic samples—points to population structure within these groups. Moreover, discontinuities in cranial traits between the early Upper Palaeolithic and later periods could suggest that the Last Glacial Maximum had a disruptive effect on populations in Europe. Differences in social organisation can often result from cultural norms regarding post-marital residence. Such differences can be tested by comparing cranial data to that of geographic information. Greater variation in male cranial traits relative to females, after controlling for location, suggests that the overall pattern of residence during the Upper Palaeolithic and Mesolithic was one of matrilocality. It has been suggested that coastal occupation was density dependent and these populations show a greater degree of sedentism than their inland counterparts. Moreover, it has been proposed that coastal areas were not continuously occupied until the Late Pleistocene due to spatial restrictions that would adversely affect reproductive opportunities. This study corroborates the pattern seen in cranial traits corresponded with that of a more sedentary population. The results are consistent with the hypothesis that coastal populations are more sedentary than inland populations during these periods. This study adds new information regarding the social dynamics of prehistoric populations in Europe and sheds light on some of the conditions that may have paved the way for the transition to agriculture
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Limb, trunk, and body weight measurements were obtained for growth series of Milne-Edwards's diademed sifaka, Propithecus diadema edwardsi, and the golden-crowned sifaka, Propithecus tattersalli. Similar measures were obtained also for primarily adults of two subspecies of the western sifaka: Propithecus verreauxi coquereli, Coquerel's sifaka, and Propithecus verreauxi verreauxi, Verreaux's sifaka. Ontogenetic series for the larger-bodied P. d. edwardsi and the smaller-bodied P. tattersalli were compared to evaluate whether species-level differences in body proportions result from the differential extension of common patterns of relative growth. In bivariate plots, both subspecies of P. verreauxi were included to examine whether these taxa also lie along a growth trajectory common to all sifakas. Analyses of the data indicate that postcranial proportions for sifakas are ontogenetically scaled, much as demonstrated previously with cranial dimensions for all three species (Ravosa, 1992). As such, P. d. edwardsi apparently develops larger overall size primarily by growing at a faster rate, but not for a longer duration of time, than P. tattersalli and P. verreauxi; this is similar to results based on cranial data. A consideration of Malagasy lemur ecology suggests that regional differences in forage quality and resource availability have strongly influenced the evolutionary development of body-size variation in sifakas. On one hand, the rainforest environment of P. d. edwardsi imposes greater selective pressures for larger body size than the dry-forest environment of P. tattersalli and P. v. coquereli, or the semi-arid climate of P. v. verreauxi. On the other hand, as progressively smaller-bodied adult sifakas are located in the east, west, and northwest, this apparently supports suggestions that adult body size is set by dry-season constraints on food quality and distribution (i.e., smaller taxa are located in more seasonal habitats such as the west and northeast). Moreover, the fact that body-size differentiation occurs primarily via differences in growth rate is also due apparently to differences in resource seasonality (and juvenile mortality risk in turn) between the eastern rainforest and the more temperate northeast and west. Most scaling coefficients for both arm and leg growth range from slight negative allometry to slight positive allometry. Given the low intermembral index for sifakas, which is also an adaptation for propulsive hindlimb-dominated jumping, this suggests that differences in adult limb proportions are largely set prenatally rather than being achieved via higher rates of postnatal hindlimb growth.(ABSTRACT TRUNCATED AT 400 WORDS)
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The correlation between diet and dental topography is of importance to paleontologists seeking to diagnose ecological adaptations in extinct taxa. Although the subject is well represented in the literature, few studies directly compare methods or evaluate dietary signals conveyed by both upper and lower molars. Here, we address this gap in our knowledge by comparing the efficacy of three measures of functional morphology for classifying an ecologically diverse sample of thirteen medium- to large-bodied platyrrhines by diet category (e.g., folivore, frugivore, hard object feeder). We used Shearing Quotient (SQ), an index derived from linear measurements of molar cutting edges and two indices of crown surface topography, Occlusal Relief (OR) and Relief Index (RFI). Using SQ, OR, and RFI, individuals were then classified by dietary category using Discriminate Function Analysis. Both upper and lower molar variables produce high classification rates in assigning individuals to diet categories, but lower molars are consistently more successful. SQs yield the highest classification rates. RFI and OR generally perform above chance. Upper molar RFI has a success rate below the level of chance. Adding molar length enhances the discriminatory power for all variables. We conclude that upper molar SQs are useful for dietary reconstruction, especially when combined with body size information. Additionally, we find that among our sample of platyrrhines, SQ remains the strongest predictor of diet, while RFI is less useful at signaling dietary differences in absence of body size information. The study demonstrates new ways for inferring the diets of extinct platyrrhine primates when both upper and lower molars are available, or, for taxa known only from upper molars. The techniques are useful in reconstructing diet in stem representatives of anthropoid clade, who share key aspects of molar morphology with extant platyrrhines.
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This paper reports on research work undertaken for the European Commission funded study GMA2/2000/32039 Very Large Transport Aircraft (VLTA) Emergency Requirements Research Evacuation Study (VERRES). A particular focus of VERRES was on evacuation issues and several large-scale evacuation trials were conducted in the CRANFIELD simulator. This paper addresses part of the research undertaken for Work Package 3 by the University of Greenwich with a focus on the analysis of the data concerning passenger use of stairs and passenger exit hesitation time analysis for upper deck slides.
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This study investigates the oceanic behavior of the lithogenic trace elements Al and Ti in the upper 200 m of the Atlantic Ocean. The distribution of both metals in the dissolved and particulate phases was assessed along an E-W transect in the eastern tropical North Atlantic (December 2009) and along a meridional Atlantic transect (April-May 2010). The surface water concentrations of particulate and dissolved Al and Ti reflected the previously observed pattern of atmospheric inputs into the Atlantic Ocean. Subsurface minima at stations with pronounced fluorescence maxima were observed, suggesting a link between biological productivity and the removal of both dissolved and particulate Al and Ti. This may include uptake mechanisms, adsorption and aggregation processes on biogenic particle surfaces and the formation of large, fast sinking biogenic particles, e.g., fecal pellets. Residence times in the upper water column (100 m) of the tropical and subtropical North Atlantic were estimated to range in the order of days to weeks in the particulate phases (Al: 3-22 days, Ti: 4-37 days) and were 0.9-3.8 years for Al and 10-31 years for Ti in the dissolved phases. Longer residence times in both phases in the South Atlantic are consistent with lower biological productivity and decreased removal rates. In the upper water column, Al was predominantly present in the dissolved form, whereas Ti mostly occurred in the particulate form. Largest deviations in the partition coefficients between the particulate and dissolved phases were found in the surface waters, together with excess dissolved Al over Ti compared to the crustal source. This likely reflects elevated dissolution of Al compared to Ti from atmospheric mineral particles.