6,467 research outputs found
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A cryptotephra record from the Lake Victoria sediment core record of holocene palaeoenvironmental change
The sediment record from Lake Victoria is an important archive of regional environmental and climatic conditions, reaching back more than 15,000 cal. years before present (15 ka BP). As the largest lake by area in East Africa, its evolution is key to understanding regional palaeohydrological change during the late Pleistocene and Holocene, including controls on the Nile River flow. As well as important palaeoenvironmental proxies, the lake contains a unique record of explosive volcanism from the central Kenyan Rift, in the form of fine-grained volcanic ash (tephra) layers, interpreted as airfall deposits. In the V95-1P core, collected from the central northern basin of the lake, tephra layers vary in concentration from 10s to 10s of 1000s of glass shards per gram of sediment. None of the tephra are visible to the naked eye, and have only been revealed through careful laboratory processing. Compositional analyses of tephra glass shards has allowed the tephra layers to be correlated to previously unrecognized eruptions of Eburru volcano around 1.2 and 3.8 ka, and Olkaria volcano, prior to 15 ka. These volcanoes lie ~300 km east of the core site in the Kenyan Rift. Our results highlight the potential for developing cryptotephra analysis as a key tool in East African palaeolimnological research. Tephra layers offer opportunities for precise correlation of palaeoenvironmental sequences, as well as windows into the eruption frequency of regional volcanoes and the dispersal of volcanic ash. Leverhulme Trust Early Career Fellowshi
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The Signs of Maize? A Reconsideration of What δ<sup>13</sup>C Values Say about Palaeodiet in the Andean Region
Palaeodietary isotope studies have long assumed C_4 signals in South American archaeological populations to be due to the consumption of maize (Zea mays), which in turn, underlie interpretations important social processes. We presents δ¹³C data from wild plants (n=89) from the south coast of Peru, which may have been significant in the diets of humans and animals in the past. A combination of these with previously published results from domesticates of the Andean region (n=144) brings the proportion of C_4 species likely to have contributed to the human dietary isotopic signal, whether directly or indirectly, to almost one third. This undermines the widespread assumption that maize is the only plant to contribute a C_4 signal to diets. By considering both direct and indirect routes whereby C_4 plants may have contributed to the human isotopic signal we show the need for a reassessment of how palaeodietary studies are interpreted in the Andes, and perhaps elsewhere in the Americas.LC would like to thank the AHRC, the Anthony Wilkins Fund and the Santander Universities Grant for Travel to Latin America for enabling this research. TCO would like to thank the Wellcome Trust.This is the author accepted manuscript. The final version is available from Springer via http://dx.doi.org/10.1007/s10745-012-9509-0
The revision partial knee classification system: understanding the causative pathology and magnitude of further surgery following partial knee arthroplasty.
AIMS: Joint registries classify all further arthroplasty procedures to a knee with an existing partial arthroplasty as revision surgery, regardless of the actual procedure performed. Relatively minor procedures, including bearing exchanges, are classified in the same way as major operations requiring augments and stems. A new classification system is proposed to acknowledge and describe the detail of these procedures, which has implications for risk, recovery, and health economics. METHODS: Classification categories were proposed by a surgical consensus group, then ranked by patients, according to perceived invasiveness and implications for recovery. In round one, 26 revision cases were classified by the consensus group. Results were tested for inter-rater reliability. In round two, four additional cases were added for clarity. Round three repeated the survey one month later, subject to inter- and intrarater reliability testing. In round four, five additional expert partial knee arthroplasty surgeons were asked to classify the 30 cases according to the proposed revision partial knee classification (RPKC) system. RESULTS: Four classes were proposed: PR1, where no bone-implant interfaces are affected; PR2, where surgery does not include conversion to total knee arthroplasty, for example, a second partial arthroplasty to a native compartment; PR3, when a standard primary total knee prosthesis is used; and PR4 when revision components are necessary. Round one resulted in 92% inter-rater agreement (Kendall's W 0.97; p < 0.005), rising to 93% in round two (Kendall's W 0.98; p < 0.001). Round three demonstrated 97% agreement (Kendall's W 0.98; p < 0.001), with high intra-rater reliability (interclass correlation coefficient (ICC) 0.99; 95% confidence interval 0.98 to 0.99). Round four resulted in 80% agreement (Kendall's W 0.92; p < 0.001). CONCLUSION: The RPKC system accounts for all procedures which may be appropriate following partial knee arthroplasty. It has been shown to be reliable, repeatable and pragmatic. The implications for patient care and health economics are discussed. Cite this article: Bone Jt Open 2021;2(8):638-645
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Dating the dead: New radiocarbon dates from the lower Ica Valley, south coast Peru
This article presents radiocarbon dates from human bone samples (n = 13) from seven pre-Columbian cemeteries in the Samaca and Ullujaya Basins of the lower Ica Valley, south coast of Peru, spanning from the end of the Early Horizon to the Inca Late Horizon. These contexts have been severely looted. Yet, in all cases, their putative dating by material culture remains is confirmed by these 14C dates. This shows that such disturbed contexts, sadly typical of the Peruvian coast, can nonetheless still yield valuable bioarchaeological and burial practice data. These dates elaborate upon an emerging picture of the absolute dating of the cultural phases of the wider south coast region, in particular casting new light on the poorly understood Middle Horizon to Late Intermediate period transition. A paucity of archaeological data for this 3-century period has been taken as evidence of some sort of environmentally or socially induced lacuna. Instead, the 14C dates presented here suggest that the basins of the lower Ica Valley were continuously occupied over this period.We thank the Ministerio de Cultural del Perú for granting permission for the fieldwork (No. 0028-2010-VMPCIC-MC) and analysis of samples for dating (No. 369-2011-VMPCIC-MC); Alberto Benavides Ganoza and the people of Samaca for facilitating fieldwork; the Arts and Humanities Research Council for LC's doctoral funding; the NERC Radiocarbon Facility for funding radiocarbon dating (grant number NF/2012/1/7 to TCO’C and LC); and Tom Higham, Diane Baker, Ingmar Unkel and Elmo Leon for their help and advice.This is the final version of the article. It first appeared from University of Arizona via http://dx.doi.org/10.2458/azu_rc.57.1834
Correlation between endometrial dating of luteal phase days 6 and 10 of the same menstrual cycle
CONTEXT: Endometrial maturation, important in the diagnosis of infertile couples, has been evaluated since 1950 using the Noyes criteria. Nevertheless, there is no consensus regarding the most suitable period of the luteal phase for performing the biopsy. OBJETIVE: This study evaluated the correlation between the histological dating of two endometrial biopsies performed in the same menstrual cycle, on luteal phase days six and ten.DESIGN: Prospective study. SETTING: Human Reproduction Division of the Federal University of São Paulo, referral center. PATIENTS:Twenty-five women complaining of infertility had their menstrual cycles monitored by ultrasound and LH plasma levels, to obtain evidence of ovulation. PROCEDURES: Endometrial biopsies were performed on luteal phase days LH+6 and LH+10 (luteal phase day 1 = LH+1 = the day that follows LH peak). Dating was done according to morphometric criteria, in which an endometrium sample is considered out of phase if the minimum maturation delay is one day. On day LH+6, blood was drawn for plasma progesterone level determination. RESULTS: All patients had an ovulatory cycle (mean LH peak: 47.4 U/L; mean follicular diameter on LH peak day: 18.9 mm; mean endometrial thickness on LH peak day: 10.3 mm; mean plasma progesterone level on day LH+6: 14.4 ng/ml). 14 patients had both biopsies in phase; 5 patients had out of phase biopsies only on day LH+6; 3 had out of phase biopsies only on day LH+10 and 3 patients had out of phase biopsies on both days. McNemar's test showed no statistical difference between these data (p>33.36%). CONCLUSIONS: The correlation found between the endometrial datings suggests that biopsies performed on either of these two days are suitable for evaluation of endometrial maturation.CONTEXTO: A verificação da maturidade endometrial, elemento diagnóstico necessário na avaliação do casal com queixa de infertilidade, vem sendo feita desde 1950 através do critério de datação histológica de Noyes. No entanto, não existe um consenso em relação ao perÃodo da fase lútea mais adequado para a colheita. OBJETIVO: Avaliar a correlação entre as datações histológicas de duas amostras de endométrio colhidas nos dias 6 e 10 da fase lútea de um mesmo ciclo menstrual. LOCAL: Setor de Reprodução Humana da Universidade Federal de São Paulo (UNIFESP). TIPO DE ESTUDO: Estudo prospectivo. Constou da comparação entre duas datações de endométrio num mesmo ciclo menstrual. PARTICIPANTES: 25 pacientes com queixa de infertilidade tiveram um ciclo menstrual monitorizado por ultra-sonografia e medida plasmática de LH, para demonstração de ovulação. PROCEDIMENTO: Biópsias de endométrio foram feitas nos dias LH+6 e LH+10 da fase lútea, considerando-se o dia seguinte ao do pico de LH como LH+1. A datação foi feita de acordo com critério morfométrico, considerando-se o endométrio como fora de fase, se o atraso de maturação mÃnimo fosse de um dia. No dia LH+6 foi feita dosagem de progesterona plasmática. RESULTADOS: Todas as pacientes apresentaram ciclos ovulatórios (média dos valores de pico de LH: 47,3 U/L; média dos diâmetros foliculares no dia do pico de LH: 18,9 mm; média das espessuras do endométrio no dia do pico de LH: 10,3 mm; média das concentrações de progesterona plasmática no dia LH+6: 14,4 ng/ml.). Em 14 pacientes, as duas biópsias estavam em fase. Houve atraso de maturação apenas no dia LH+6 em cinco pacientes; apenas no dia LH+10 em três pacientes e, nos dois dias, em três pacientes. Não houve diferença estatÃstica entre esses valores (teste de McNemar, p=33,36%). CONCLUSÕES: Os resultados sugerem que a colheita do endométrio em qualquer dos dias (sexto ou décimo) da fase lútea fornece resultados semelhantes em relação à maturidade endometrial.Universidade Federal de São Paulo (UNIFESP)UNIFESPSciEL
Social Network Characteristics and Psychological Well-Being: A Replication and Extension
This article represents a replication and extension of a previous study by Israel and her colleagues that investigated the relationship between psychological well-being and social network characteristics. The present research included both a comparable sample of white women (N=104) between the ages of 60 and 68 (as in the original study), and a more extensive adult population of men and women (N=718) between the ages of 50 and 95. The network characteristics examined are categorized along three broad dimensions: Structure—linkages in the overall network (size and density); interaction-nature of the linkages themselves (frequency, geographic dispersion, and reciprocity); and functions that networks provide (affective support and instrumental support). The results indicate a predominance of comparable findings for both the replication and extension studies. Of the eight network characteristics examined, the results of five of the regression analyses were the same across all three studies. The network characteristics of size, density, geographic dispersion, reciprocal instrumental support, and instrumental support did not make a significant contribution to the variance in psychological well-being. Of the other three network characteristics, the effect of frequency of interaction varied across the studies, and a pattern of significant results was found for affective support and reciprocal affective support. A discussion of this evidence in light of current literature and implications for practice and research is included.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/67842/2/10.1177_109019818701400406.pd
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Conformal Printing of Graphene for Single- and Multilayered Devices onto Arbitrarily Shaped 3D Surfaces
Printing has drawn a lot of attention as a means of low per-unit cost and high throughput patterning of graphene inks for scaled-up thin-form factor device manufacturing. However, traditional printing processes require a flat surface and are incapable of achieving patterning on to 3D objects. Here, we present a conformal printing method to achieve functional graphene-based patterns on to arbitrarily-shaped surfaces. Using experimental design, we formulate a water-insoluble graphene ink with optimum conductivity. We then print single and multi-layered electrically functional structures on to a sacrificial layer using conventional screen printing. The print is then floated on water, allowing the dissolution of the sacrificial layer, while retaining the functional patterns. The single and multilayer patterns can then be directly transferred on to arbitrarily-shaped 3D objects without requiring any post deposition processing. Using this technique, we demonstrate conformal printing of single and multilayer functional devices that include joule heaters, resistive deformation sensors and proximity sensors on hard, flexible and soft substrates, such as glass, latex, thermoplastics, textiles, and even candies and marshmallows. Our simple strategy offers great promises to add new device and sensing functionalities to previously inert 3D surfaces.EPSRC (EP/L016087/1)
Graphene Flagshi
Conformal Printing of Graphene for Single- and Multilayered Devices onto Arbitrarily Shaped 3D Surfaces
Printing has drawn a lot of attention as a means of low per-unit cost and
high throughput patterning of graphene inks for scaled-up thin-form factor
device manufacturing. However, traditional printing processes require a flat
surface and are incapable of achieving patterning on to 3D objects. Here, we
present a conformal printing method to achieve functional graphene-based
patterns on to arbitrarily-shaped surfaces. Using experimental design, we
formulate a water-insoluble graphene ink with optimum conductivity. We then
print single and multi-layered electrically functional structures on to a
sacrificial layer using conventional screen printing. The print is then floated
on water, allowing the dissolution of the sacrificial layer, while retaining
the functional patterns. The single and multilayer patterns can then be
directly transferred on to arbitrarily-shaped 3D objects without requiring any
post deposition processing. Using this technique, we demonstrate conformal
printing of single and multilayer functional devices that include joule
heaters, resistive strain sensors and proximity sensors on hard, flexible and
soft substrates, such as glass, latex, thermoplastics, textiles, and even
candies and marshmallows. Our simple strategy offers great promises to add new
device and sensing functionalities to previously inert 3D surfaces.EPSRC (EP/L016087/1)
Graphene Flagshi
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