272 research outputs found
Interaction of a glow discharge with an ion beam
The aim is to derive a fluid model, of hydrodynamic/diffusion type, describing the interaction of a glow discharge with an ion beam at atmospheric pressure
Diffusion limits of the Lorentz model: Asymptotic preserving schemes
This paper deals with the diffusion limit of a kinetic equation where the collisions are modeled by a Lorentz type operator. The main aim is to construct a discrete scheme to approximate this equation which gives for any value of the Knudsen number, and in particular at the diffusive limit, the right discrete diffusion equation with the same value of the diffusion coefficient as in the continuous case. We are also naturally interested with a discretization which can be used with few velocity discretization points, in order to reduce the cost of computation
Something fishy in the Great Lakes?:The reappraisal of early pottery use in north-eastern North America.
Lipid residue analysis has recently been applied to investigate the adoption of pottery by Early Woodland hunter-gatherers in north-eastern North America. Results, however, have proven contradictory, especially regarding the extent towhich early ceramics were used for processing aquatic resources. Here, the authors argue that this inconsistency is due to the use of different analytical procedures and criteria for identifying aquatic organisms, rather than anyactual variations in pottery use. By applying robust analytical criteria and methods to Early Woodland pottery from the Great Lakes region, the authors present evidence supporting their hypothesis that such pottery was indeed used for processing aquatic resource
O efeito dos alongamentos na espasticidade, marcha e equilĂbrio em crianças com paralisia cerebral espástica: revisĂŁo bibliográfica
Projeto de Graduação apresentado Ă Universidade Fernando Pessoa como parte dos requisitos para obtenção do grau de Licenciada em FisioterapiaObjetivo: Verificar os efeitos dos alongamentos sobre na espasticidade, a marcha e o equilĂbrio em crianças com paralisia cerebral espástica. Metodologia: Foi realizada uma pesquisa nas bases de dados PubMed, PEDro e Web of Science com a utilização de palavras-chaves. Apenas estudos randomizados controlados foram incluĂdos no estudo. Os estudos foram analisados usando a Physiotherapy Evidence Database scoring scale (PEDro). Resultados: Nesta revisĂŁo foram incluĂdos 6 artigos que cumpriam os critĂ©rios de elegibilidade com score medio de 5,5/10 na escala de PEDro. ConclusĂŁo: Os estudos incluĂdos nesta revisĂŁo sugerem que os alongamentos isoladamente nĂŁo tĂŞm efeitos benĂ©ficos significativos na melhoria da espasticidade, da marcha e do equilĂbrio.Objective: To verify the effects of stretching on spasticity, gait and balance in children with spastic cerebral palsy. Methodology: A search was conducted in the PubMed, PEDro and Web of Science databases using keywords. Only randomized controlled studies were included in the study. The studies were analysed using Physiotherapy Evidence Database scoring scale (PEDro). Results: Six articles meeting the eligibility criteria with a median score of 5,5/10 on the PEDro scale were included in this review. Conclusion: The studies included in this review suggest that stretching alone has no significant beneficial effects on improving spasticity, gait and balance.N/
First lipid residue analysis of Early Neolithic pottery from Swifterbant (the Netherlands, ca. 4300–4000 BC)
This paper focuses on the functional analysis of Swifterbant pottery from North-western Europe (ca. 4300–4000 BC) through lipid residue analysis. The main aim is to understand the role of pottery in terms of its relation to hunter-fisher-gatherer lifestyle, and the change in available food resources brought about by the arrival of domesticated animal and plant products. We conducted lipid residue analysis of 62 samples from three Swifterbant sites S2, S3 and S4. A combined approach using both GC-MS and GC-C-IRMS of residues absorbed into the ceramic was employed to identify their context. Our results demonstrate that Swifterbant ceramics were used exclusively for processing aquatic resources. We also found no evidence of inter-site variation in the use of pottery or variation based on both typological and technological features of the pottery. We found no evidence for any domesticated resources despite their presence in the faunal and botanical assemblages
Resource Processing, Early Pottery and the Emergence of Kitoi Culture in Cis-Baikal:Insights from Lipid Residue Analysis of an Early Neolithic Ceramic Assemblage from the Gorelyi Les Habitation Site, Eastern Siberia
In the early Holocene, Mesolithic hunter-gatherer communities inhabiting the Cis-Baikal region of Eastern Siberia were participating in a series of important cultural changes. These included the establishment of large cemeteries in the Angara Valley and on the Southwest shores of Lake Baikal, culminating in the formation of the distinctive Early Neolithic Kitoi cultural pattern ca. 7560 cal. BP. Around the same time, the appearance of clay pots in a few Kitoi graves and at some contemporary habitation sites marks the formal transition to the Early Neolithic, which is defined in Russian archaeology by the emergence of pottery (and not the transition to farming). Little is known about how this early pottery was used, and why it was first adopted into the region. This pilot-study presents lipid-residue analysis of a selection of sherds from the oldest and relatively well-dated pottery assemblage in the Cis-Baikal region, which was recovered from the Gorelyi Les habitation site. The results indicate that the pots had been used to process a broad spectrum of food resources, including ruminants, fish and plants, and possibly resin and other by-products derived from pine trees, suggesting that the vessels were being used as general-purpose cooking containers. We conclude that there is scope for a much larger-scale investigation of diversity and change in prehistoric pottery use in Cis-Baikal, and that this research would improve current understandings of the diet, health and subsistence strategies of the Kitoi and other prehistoric populations
Investigating the function of prehistoric stone bowls and griddle stones in the Aleutian Islands by lipid residue analysis
The earliest durable cooking technologies found in Alaska are stone bowls and griddle stones recovered from the Aleutian Islands. This article aims to identify the function of these artefacts. Molecular and chemical analyses of carbonised residues found on their surfaces confirm that these artefacts were used to process marine resources. Both artefacts have high lipid content and C:N ratios, suggesting they were used to process oily substances. Stable isotope results of individual lipids suggest that they were used to process different sets of resources within the aquatic spectrum as griddle stones have slightly more 13C-depleted lipids than stone bowls, possibly indicating more variable use. Integration of these results with archaeological and ethnographic data leads us to infer that griddle stones were used for cooking a diversity of aquatic resources, possibly with the addition of plant foods, whereas stone bowls were specifically used to render marine mammal fats. We further hypothesize that a sudden peak in stone bowl frequencies at 4000–3000 cal yr BP was connected to a Neoglacial cold spell bringing sea ice conditions to the Aleutian Islands. This may have led to new subsistence strategies in which the rendering of marine mammal fats played a central role
The use of Lapita pottery : results from the first analysis of lipid residues
Biomolecular and isotopic characterisation of absorbed organic residues have been performed on eight dentate-stamped and two plain Lapita potsherds from the site of Teouma, in Vanuatu. Lipid profiles associated with decorated pots are homogenous, suggesting that similar food types or mixtures of food types were placed in these vessels. This suggests a high degree of consistency in the use of Lapita decorated pots, irrespective of the morphological and stylistic variation of these vessels. Data obtained from single-compound isotope analysis are also not consistent with marine resources as potential food sources for Lapita vessels. The absence of such commonly consumed, ubiquitous and easily accessible resources in Lapita vessels suggests that these pots were not manufactured to be used for ordinary occasions and day-to-day food consumption. This is the first time tangible data related to the use of these vessels are provided to support this claim in addition to contextual inferences
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