56,053 research outputs found
The importance of accounting for the area of the medullary cavity in cross-sectional geometry: A test based on the femoral midshaft
No full textIn cross-sectional geometric (CSG) studies, both the subperiosteal and endosteal contours are considered important factors in determining bone bending rigidity. Recently, regression equations predicting CSG properties from a section's external dimensions were developed in a world-wide sample of human long bones. The results showed high correlations between some subperiosteally derived and actual CSG parameters. We present a theoretical model that further explores the influence of endosteal dimensions on CSG properties. We compare two hypothetical femoral midshaft samples with the same total subperiosteal area but with percentages of cortical bone at the opposite ends of published human variation for population sample means. Even in this relatively uncommon scenario, the difference between the samples in the resultant means for predicted femoral polar second moment of area (J) appears to be modest: power analysis indicates that a minimum sample size of 61 is needed to detect the difference 90% of the time via a t-test. Moreover, endosteal area can be predicted-although with substantial error-from periosteal area. Despite this error, including this relationship in subperiosteally derived estimates of J produces sample mean estimates close to true mean values. Power analyses reveal that when similar samples are used to develop prediction equations, a minimum sample of hundreds or more may be needed to distinguish a predicted mean J from the true mean J. These results further justify the use of regression equations estimating J from periosteal contours when analyzing behaviorally induced changes in bone rigidity in ancient populations, when it is not possible to measure endosteal dimensions. However, in other situations involving comparisons of individual values, growth trends, and senescence, where relative cortical thickness may vary greatly, inclusion of endosteal dimensions is still important
Behavioral Differences Between Near Eastern Neanderthals and the Early Modern Humans from Skhul and Qafzeh: An Assessment Based on Comparative Samples of Holocene Humans
No full textThe differences and similarities between Near Eastern Neanderthals and the early modern humans from Skhul and Qafzeh in Israel have long been a point of study and debate. Conclusions about the magnitude and especially the implications of the differences have served as evidence to support or refute competing hypotheses about their cultural and biological differences. Here we revisit the controversy by assessing the midshaft shapes and robusticity of the femur, tibial, humerus, and radius of these Middle Paleolithic samples in comparison to European Neanderthals, Gravettian modern humans, several modern individuals from other late Pleistocene cultures in Europe and Israel, and a diverse set of Holocene humans from around the globe. The results show that the Near Eastern Neanderthals resemble European Neanderthals as well as a diverse array of modern agriculturalists and intensive foragers. In contrast, the people from Skhul and Qafzeh are much more distinct from recent samples but bear a degree of resemblance to Khoesan and Zulu males and females, Amud 1, and Ohalo 2. Additional insights emerge when the upper and lower limb are considered separately, but the result remains that the early moderns rather than Neanderthals seem to have faced an unusual, or at least uncommon, set of mechanical demands in comparison to most of the more recent groups
Changes in skeletal robusticity in an iron age agropastoral group: The samnites from the Alfedena necropolis (Abruzzo, Central Italy)
No full textCross-sectional geometrical (CSG) properties of an Iron Age Samnite group from the Alfedena necropolis (Abruzzo, Italy, 2600-2400 B. P.) are compared with a Ligurian Neolithic sample (6000-5500 B. P.). In the period under examination, Samnites were organized in a tribal confederation led by patrilinear aristocracies, indicating incipient social stratification. In comparison, Neolithic society lacked clear signs of social hierarchy. The subsistence of both groups was mainly based on pastoralism and agriculture, but changes in habitual behavior are expected due to the socio-economic transformations that characterized the Iron Age. The Samnites' warlike ideology suggests that unimanual weapon-use and training would have become frequent for males. The intensification of agriculture and the adoption of transhumant pastoralism, performed by a smaller subset of the population, likely led to a lower average level of logistic mobility. The strongly genderized ideology of the period suggests a strict sexual division of labor, with women primarily performing sedentary tasks. CSG properties based on periosteal contours were calculated for humeri, femora, and tibiae (N = 61). Results corroborated the expectations: Alfedena males show substantial humeral bilateral asymmetry, indicating prevalent use of one arm, likely due to weapon training. In both sexes lower limb results indicate reduced mobility with respect to the Neolithic group. Sexual dimorphism is significant in both humeral asymmetry and lower limb indicators of mobility. Although both groups could be broadly defined as agropastoral based on archeological and historical evidence, CSG analysis confirmed important differences in habitual behavior. Am J Phys Anthropol 144:119-130, 2011. (C) 2010 Wiley-Liss, Inc
Portrait of Alan Pearson in his Lyttelton abode.
No full textLower right (l.r.) with brush: M.D.S. 91; verso in crayon in Alan Pearson’s hand: Portrait of Alan Pearson in his Lyttelton abode 1991 by M. Smither
Geologic atlas of the United States : topography, areal geology, economic geology, structure sections / 118 Greeneville Folio : Tennesse - North Carolina
No full textHenry Gannett ; Gilbert Thompson ; W. C. Kerr ; S. S: Gannett ; F. M. Pearson ; R. O. Gordon ; R. L. LongstreetList of Sheets: Topography, Areal Geology, Structure-SectionIndirektes handschriftliches Exlibris: "1906, 509", das ist United States Geological Survey Washington Exemplar der ETH-BI
An integrated operational system to reduce O&M cost of offshore wind farms
No full textOffshore wind is a relatively new industry and it is generally more expensive to generate electricity than many alternative renewable sources. Operation & Maintenance (O&M) makes up a significant part of the overall cost of running Offshore Wind Turbines (OWT). Since the O&M associated responsibility is shared among turbine manufacturers, wind farm operators and the offshore transmission owners, this has inevitably led to lack of information, duplication of effort and less efficiency. Big data analytics is one great technique that will drive future growth. In this paper, an integrated operational system of offshore wind farm is proposed deploying big data analytics. Firstly, the current state of the O&M of offshore wind farm and the big data analytics are introduced. Afterwards, a predictive maintenance model and a maintenance implementation model are proposed, and an integrated operational system is developed incorporating those two models in order to optimize maintenance planning and implementation. Finally, the possible contribution of such a system to a more effective O&M of offshore wind farm is discussed.Green Open Access added to TU Delft Institutional Repository 'You share, we take care!' - Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Transport Engineering and Logistic
Dispelling the Myths Behind First-author Citation Counts
No full textWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
The long-wavelength view of GG Tau A: rocks in the ring world
No full textWe present the first detection of GG Tau A at centimetre wavelengths, made with the Arcminute Microkelvin Imager Large Array at a frequency of 16 GHz (λ = 1.8 cm). The source is detected at >6 σrms with an integrated flux density of S16GHz = 249 ± 45 µJy. We use these new centimetre-wave data, in conjunction with additional measurements compiled from the literature, to investigate the long-wavelength tail of the dust emission from this unusual protoplanetary system. We use an MCMC-based method to determine maximum likelihood parameters for a simple parametric spectral model and consider the opacity and mass of the dust contributing to the microwave emission. We derive a dust mass of Md ~ 0.1 Msun, constrain the dimensions of the emitting region and find that the opacity index at λ > 7 mm is less than unity, implying a contribution to the dust population from grains exceeding ~4 cm in size. We suggest that this indicates coagulation within the GG Tau A system has proceeded to the point where dust grains have grown to the size of small rocks with dimensions of a few centimetres. Considering the relatively young age of the GG Tau association in combination with the low derived disc mass, we suggest that this system may provide a useful test case for rapid core accretion planet formation models
The synthesis and infrared spectra of some group VA chalcogenides
No full textThe preparation of compounds having the general formula R���MX, where R is an alkyl group, M is P, As or Sb and X is O, S, Se or Te has been carried put previously. The fundamental stretching frequency, ��[subscript S](M=X), has also been determined for P=O, P=S, P=Se, As=O, As=S and As=Se bonds. In the present work the assignment of the M=X stretching frequencies has been extended to include 20 or more compounds, including the alkyl stibine oxides [��[subscript S](Sb=O) at 450=680 cm�����], alkyl stibine sulfides [��[subscript S](Sb=S) at 420-450 cm�����], alkyl stibine selenides [��[subscript S](Sb=Se) at 270-300 cm�����] and alkyl phosphine tellurides [��[subscript S](P=Te) at 400-520 cm�����]. A correlation has been observed which related the location of these frequencies to the total mass of the molecule and the masses and electronegativities of the respective atoms, M and X. A regression analysis was carried out for the series of R���MX compounds, while maintaining R constant. The correlation coefficients and the standard deviations for the regression equations were of the same order of magnitude for all the series. For example, in the case of R=butyl, the following relationship was found: ��[subscript S](M=X)(cm�����) = 121.62 + 215.09 (��m/m[subscript M]m[subscript X])[superscript 1/2]E[subscript M]E[subscript X] with a correlation coefficient of 0.987 and a standard deviation of 43 cm�����. ��m = total mass, m[subscript M] = mass of M, m[subscript X] = mass of X; ��[subscript M] and ��[subscript X], the electronegativities of M and X, respectively. The absolute integrated absorption intensities for five trialkylstibine sulfides were determined. These values were all of the same order of magnitude. For triethylstibine sulfide A = 6.1 x 10�� 1/mol cm��. It was also found that the absolute intensities were linearly dependent with Taft's polar and steric parameters
Goodness of fit by Neyman-Pearson testing
No full textThe Neyman–Pearson strategy for hypothesis testing can be employed for goodness of fit if the alternative hypothesis is selected from data by exploring a rich parametrised family of models, while controlling the impact of statistical fluctuations. The New Physics Learning Machine (NPLM) methodology has been developed as a concrete implementation of this idea, to target the detection of new physical effects in the context of high energy physics collider experiments. In this paper we conduct a comparison of this approach to goodness of fit with others, in particular with classifier-based strategies that share strong similarities with NPLM. From our comparison, NPLM emerges as the more sensitive test to small departures of the data from the expected distribution and not biased towards detecting specific types of anomalies. These features make it suited for agnostic searches for new physics at collider experiments. Its deployment in other scientific and industrial scenarios should be investigated
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