Preconditioned iterative methods for convection diffusion and related boundary value problems

AbstractWe develop and analyze preconditioners for the iterative solution of the system of equations arising from the discretization of multi-dimensional singularity perturbed boundary value problems. This includes a class of convection diffusion models. The choice of preconditioner is crucial for the efficient solution of the system of equations. In particular, it is necessary to choose a preconditioner that substantially reduces the condition number κ both for small grid size h and for large values of the parameter K multiplying the convection terms. A class of preconditioners is analyzed that is inexpensive to implement and for which κ = 0(1) as h→0 and κ = (1 + K12) as K → ∞ for some convection diffusion problems with positive definite symmetric part. This result is then used to develop an algorithm with work estimate 0(1 + K12as K → ∞ for a more general class of convection diffusion problems including those with indefinite symmetric part. Numerical experiments using a symmetric multigrid preconditioner demonstrate the effectiveness of the numerical method even for large problems

Skeletal anomalies in the Neandertal family of El Sidron (Spain) support a role of inbreeding in Neandertal extinction

Neandertals disappeared from the fossil record around 40,000 bp, after a demographic history of small and isolated groups with high but variable levels of inbreeding, and episodes of interbreeding with other Paleolithic hominins. It is reasonable to expect that high levels of endogamy could be expressed in the skeleton of at least some Neandertal groups. Genetic studies indicate that the 13 individuals from the site of El Sidrón, Spain, dated around 49,000 bp, constituted a closely related kin group, making these Neandertals an appropriate case study for the observation of skeletal signs of inbreeding. We present the complete study of the 1674 identified skeletal specimens from El Sidrón. Altogether, 17 congenital anomalies were observed (narrowing of the internal nasal fossa, retained deciduous canine, clefts of the first cervical vertebra, unilateral hypoplasia of the second cervical vertebra, clefting of the twelfth thoracic vertebra, diminutive thoracic or lumbar rib, os centrale carpi and bipartite scaphoid, tripartite patella, left foot anomaly and cuboid-navicular coalition), with at least four individuals presenting congenital conditions (clefts of the first cervical vertebra). At 49,000 years ago, the Neandertals from El Sidrón, with genetic and skeletal evidence of inbreeding, could be representative of the beginning of the demographic collapse of this hominin phenotype

Response to Comment on "The growth pattern of Neandertals, reconstructed from a juvenile skeleton from El Sidrón (Spain)".

This is the author’s version of the work. It is posted here by permission of the AAAS for personal use, not for redistribution. The definitive version was published in Rosas, A., et al. (2018). "Response to Comment on “The growth pattern of Neandertals, reconstructed from a juvenile skeleton from El Sidrón (Spain)”." Science 359(6380). on Science 09 Mar 2018: Vol. 359, Issue 6380, eaar3820, DOI: 10.1126/science.aar3820The comment by DeSilva challenges our suggestion that brain growth of the El Sidrón J1 Neandertal was still incomplete at 7.7 years of age. Evidence suggests that endocranial volume is likely to represent less than 90% adult size at El Sidrón as well as Neandertal male plus Krapina samples, in line with further evidence from endocranial surface histology and dural sinus groove size

La Cueva de El Sidrón (Piloña Asturias)

Estado de las excavaciones y estudios en la Cueva de El Sidrón (PIloña, Asturias)

El grupu neandertal de la Cueva d' El Sidrón (Borines, Piloña)

El artículo está en la lengua asturianaPeer reviewe

Age and date for early arrival of the Acheulian in Europe (Barranc de la Boella, la Canonja, Spain)

The first arrivals of hominin populations into Eurasia during the Early Pleistocene are currently considered to have occurred as short and poorly dated biological dispersions. Questions as to the tempo and mode of these early prehistoric settlements have given rise to debates concerning the taxonomic significance of the lithic assemblages, as trace fossils, and the geographical distribution of the technological traditions found in the Lower Palaeolithic record. Here, we report on the Barranc de la Boella site which has yielded a lithic assemblage dating to ,1 million years ago that includes large cutting tools (LCT). We argue that distinct technological traditions coexisted in the Iberian archaeological repertoires of the late Early Pleistocene age in a similar way to the earliest sub-Saharan African artefact assemblages. These differences between stone tool assemblages may be attributed to the different chronologies of hominin dispersal events. The archaeological record of Barranc de la Boella completes the geographical distribution of LCT assemblages across southern Eurasia during the EMPT (Early-Middle Pleistocene Transition, circa 942 to 641 kyr). Up to now, chronology of the earliest European LCT assemblages is based on the abundant Palaeolithic record found in terrace river sequences which have been dated to the end of the EMPT and later. However, the findings at Barranc de la Boella suggest that early LCT lithic assemblages appeared in the SW of Europe during earlier hominin dispersal episodes before the definitive colonization of temperate Eurasia took place.The research at Barranc de la Boella has been carried out with the financial support of the Spanish Ministerio de Economı´a y Competitividad (CGL2012- 36682; CGL2012-38358, CGL2012-38434-C03-03 and CGL2010-15326; MICINN project HAR2009-7223/HIST), Generalitat de Catalunya, AGAUR agence (projects 2014SGR-901; 2014SGR-899; 2009SGR-324, 2009PBR-0033 and 2009SGR-188) and Junta de Castilla y Leo´n BU1004A09. Financial support for Barranc de la Boella field work and archaeological excavations is provided by the Ajuntament de la Canonja and Departament de Cultura (Servei d’Arqueologia i Paleontologia) de la Generalitat de Catalunya. A. Carrancho’s research was funded by the International Excellence Programme, Reinforcement subprogramme of the Spanish Ministry of Education. I. Lozano-Ferna´ndez acknowledges the pre-doctoral grant from the Fundacio´n Atapuerca. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript

Diet and cultural diversity in Neanderthals and modern humans from dental macrowear analyses

Neanderthals have been traditionally described to be at the very top of the food chain, with a diet consisting almost exclusively of meat. On the other hand, anatomically modern humans (AMH) are thought to be a more flexible species with the exploitation of various food sources. Here we analyze dental macrowear of a large sample of Neanderthal and AMH postcanine teeth from different chronological and geographical areas of Europe and the Near East, applying a well-established method called occlusal fingerprint analysis (OFA). This digital approach is based on the identification and analysis of attrition and abrasive occlusal wear facets (defined as polished homologous areas with well-defined borders) with the aim to reconstruct the jaw movements responsible for their formation. Thus, it enables to obtain information on dietary and non-dietary habits of these populations. Wear facet size and distribution seem to correlate well with diet, showing a large variation within Neanderthals and AMH, which mostly depends on the habitats they inhabited. We found ecomorphological signals distinguishing populations who lived in cold habitats from those who inhabited warm climatic conditions, suggesting an increase in meat consumption at the northern latitudes. In contrast, wear facet inclination is strongly influenced by the environmental abrasiveness accidentally introduced in the mouth through food preparation methods. In addition, we have also identified non-dietary wear on the postcanine dentition in Mediterranean populations that suggests the use of teeth as tools for daily task activities

How much musculoskeletal variability did Neandertals accumulate? The study of the lower limbs entheses of the Neandertal sample from El Sidr\uf3n

Rarely have entheses been systematically utilized in the field of human evolution, but investigation of their morphological variability (robusticity) could provide new insights on their evolutionary meaning in the European Neandertal populations. The aim of this work is to study the entheses and joint features of the lower limbs of El Sidr\uf3n Neandertals (Spain; 49kyrs), utilizing scoring standardized methods developed on modern samples. Paleobiology, growth and development of both El Sidr\uf3n juveniles and adults are explored and compared with those of Krapina Neandertals (Croatia, 130 Kyrs) and European modern humans. The morphological patterns of the gluteus maximus and vastus intermedius entheses of El Sidr\uf3n, Krapina and modern humans are different from one another. Both Neandertal groups show a definite enthesis design for the gluteus maximus, with little intrapopulation variability with respect to modern humans, that display a wider range of morphological variability. The gluteus maximus enthesis of El Sidr\uf3n shows the osseous features of fibrous entheses, as in modern humans, while the Krapina sample shows the aspects of fibrocartilaginous ones. The morphology and anatomical pattern of this enthesis is already established during growth in all of the three human groups. One out of two and three out of five adult femurs of El Sidr\uf3n and Krapina, respectively, show the imprint of m. vastus intermedius, absent in their juvenile specimens and in the modern samples. The little intra-population and evident inter-population variability of the two Neandertal samples is likely due to long-term history of small, isolate populations with high levels of inbreeding also living in different ecological conditions. The comparison of different anatomical entheseal pattern (fibruous vs. fibrocartilagineous) of the Neandertals and modern humans opens new functional perspectives

How much musculoskeletal variability did Neandertals accumulate? The study of the lower limbs entheses of the Neandertal sample from El Sidrón, Asturias, Spain.

Rarely have entheses been systematically utilized in the field of human evolution, but investigation of their morphological variability (robusticity) could provide new insights on their evolutionary meaning in the European Neandertal populations. The aim of this work is to study the entheses and joint features of the lower limbs of El Sidr\uf3n Neandertals (Spain; 49kyrs), utilizing scoring standardized methods developed on modern samples. Paleobiology, growth and development of both El Sidr\uf3n juveniles and adults are explored and compared with those of Krapina Neandertals (Croatia, 130 Kyrs) and European modern humans. The morphological patterns of the gluteus maximus and vastus intermedius entheses of El Sidr\uf3n, Krapina and modern humans are different from one another. Both Neandertal groups show a definite enthesis design for the gluteus maximus, with little intrapopulation variability with respect to modern humans, that display a wider range of morphological variability. The gluteus maximus enthesis of El Sidr\uf3n shows the osseous features of fibrous entheses, as in modern humans, while the Krapina sample shows the aspects of fibrocartilaginous ones. The morphology and anatomical pattern of this enthesis is already established during growth in all of the three human groups. One out of two and three out of five adult femurs of El Sidr\uf3n and Krapina, respectively, show the imprint of m. vastus intermedius, absent in their juvenile specimens and in the modern samples. The little intra-population and evident inter-population variability of the two Neandertal samples is likely due to long-term history of small, isolate populations with high levels of inbreeding also living in different ecological conditions. The comparison of different anatomical entheseal pattern (fibruous vs. fibrocartilagineous) of the Neandertals and modern humans opens new functional perspectives

The growth pattern of Neandertals, reconstructed from a juvenile skeleton from El Sidron (Spain)

Ontogenetic studies help us understand the processes of evolutionary change. Previous studies on Neandertals have focused mainly on dental development and inferred an accelerated pace of general growth. We report on a juvenile partial skeleton (El Sidrón J1) preserving cranio-dental and postcranial remains. We used dental histology to estimate the age at death to be 7.7 years. Maturation of most elements fell within the expected range of modern humans at this age. The exceptions were the atlas and mid-thoracic vertebrae, which remained at the 5- to 6-year stage of development. Furthermore, endocranial features suggest that brain growth was not yet completed. The vertebral maturation pattern and extended brain growth most likely reflect Neandertal physiology and ontogenetic energy constraints rather than any fundamental difference in the overall pace of growth in this extinct human