743 research outputs found

    Integrated waveguides and deterministically positioned nitrogen vacancy centers in diamond created by femtosecond laser writing

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    Diamond's nitrogen vacancy (NV) center is an optically active defect with long spin coherence times, showing great potential for both efficient nanoscale magnetometry and quantum information processing schemes. Recently, both the formation of buried 3D optical waveguides and high quality single NVs in diamond were demonstrated using the versatile femtosecond laser-writing technique. However, until now, combining these technologies has been an outstanding challenge. In this work, we fabricate laser written photonic waveguides in quantum grade diamond which are aligned to within micron resolution to single laser-written NVs, enabling an integrated platform providing deterministically positioned waveguide-coupled NVs. This fabrication technology opens the way towards on-chip optical routing of single photons between NVs and optically integrated spin-based sensing

    Cephalic salt gland evolution in Mesozoic pelagic crocodylomorphs

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    Secondarily marine tetrapod lineages have independently evolved osmoregulatory adaptations for life in salt water but inferring physiological changes in extinct marine tetrapods is difficult. The Mesozoic crocodylomorph clade Thalattosuchia is unique in having both direct evidence from natural endocasts and several proposed osteological correlates for salt exocrine glands. Here, we investigate salt gland evolution in thalattosuchians by creating endocranial reconstructions from CT scans of eight taxa (one basal thalattosuchian, one teleosauroid, two basal metriorhynchoids and four metriorhynchids) and four outgroups (three extant crocodylians and the basal crocodyliform Protosuchus) to identify salt gland osteological correlates. All metriorhynchoids show dorsolateral nasal cavity expansions corresponding to the location of nasal salt glands in natural casts, but smaller expansions in teleosauroids correspond more with the cartilaginous nasal capsule. The different sizes of these expansions suggest the following evolutionary sequence: (1) plesiomorphically small glands present in semi-aquatic teleosauroids draining through the nasal vestibule; (2) moderately sized glands in the basalmost metriorhynchoid Pelagosaurus; and (3) hypertrophied glands in the clade comprising Eoneustes and metriorhynchids, with a pre-orbital fenestra providing a novel exit for salt drainage. The large gland size inferred from basal metriorhynchoids indicates advanced osmoregulation occurred while metriorhynchoids were semi-aquatic. This pattern does not precisely fit into current models of physiological evolution in marine tetrapods and suggests a unique sequence of changes as thalattosuchians transitioned from land to sea.Fil: Cowgill, T.. University of Edinburgh; Reino UnidoFil: Young, M.. University of Edinburgh; Reino UnidoFil: Schwab, J.. University of Edinburgh; Reino UnidoFil: Walsh, S.. National Museum Of Scotland; Reino UnidoFil: Witmer, Lawrence. Ohio University; Estados UnidosFil: Herrera, Laura Yanina. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. División Paleontología Vertebrados; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata; ArgentinaFil: Dollman, K.. University of the Witwatersrand; SudáfricaFil: Turner, A. H.. State University of New York. Stony Brook University; Estados UnidosFil: Brusatte, S.. University of Edinburgh; Reino Unid

    Fatigue evaluation in maintenance and assembly operations by digital human simulation

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    Virtual human techniques have been used a lot in industrial design in order to consider human factors and ergonomics as early as possible. The physical status (the physical capacity of virtual human) has been mostly treated as invariable in the current available human simulation tools, while indeed the physical capacity varies along time in an operation and the change of the physical capacity depends on the history of the work as well. Virtual Human Status is proposed in this paper in order to assess the difficulty of manual handling operations, especially from the physical perspective. The decrease of the physical capacity before and after an operation is used as an index to indicate the work difficulty. The reduction of physical strength is simulated in a theoretical approach on the basis of a fatigue model in which fatigue resistances of different muscle groups were regressed from 24 existing maximum endurance time (MET) models. A framework based on digital human modeling technique is established to realize the comparison of physical status. An assembly case in airplane assembly is simulated and analyzed under the framework. The endurance time and the decrease of the joint moment strengths are simulated. The experimental result in simulated operations under laboratory conditions confirms the feasibility of the theoretical approach

    Braincase of panphagia protos (dinosauria, sauropodomorpha)

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    We describe a partial braincase of the basal sauropodomorph Panphagia protos from the Upper Triassic (midCarnian) horizons of the Ischigualasto Formation. The disarticulated braincase from a subadult individual includes one frontal, both parietals, one prootic, and the supraoccipital. The frontal is longer anteroposteriorly than it is wide transversely, has a small anterolateral process, and an elongate oval depression for the olfactory bulb. The supraoccipital is broader transversely than it is deep dorsoventrally and lacks a pronounced median nuchal eminence. Some braincase features that characterize more derived basal sauropodomorphs are not present in Panphagia, including a broader frontal and reduced anterior tympanic and floccular recesses. Panphagia appears to represent an early stage in the evolution of sauropodomorph dinosaurs.Describimos la caja craneana parcial del sauropodomorfo basal Panphagia protos proveniente de horizontes del Triásico superior (Carniano medio) de la Formación Ischigualasto. La caja craneana desarticulada es de un individuo sub-adulto e incluye un frontal, dos parietales, un proótico y el supraoccipital. El frontal es más largo anteroposteriormente que ancho transversalmente, tiene un pequeño proceso anterolateral y una depresión alargada oval para el bulbo olfatorio. El supraoccipital es transversalmente más ancho que dorsoventralmente alto y carece de una eminencia nucal media pronunciada. Algunas de las características que caracterizan los neurocráneos de sauropodomorfos basales más derivados no están presentes en Panphagia, incluyendo el frontal ancho y la reducción de las cavidades timpánica anterior y flocular. Panphagia parece representar una etapa temprana en la evolución de los dinosaurios sauropodomorfos.Fil: Martínez, Ricardo Néstor. Universidad Nacional de San Juan. Facultad de Ciencias Exactas, Fisicas y Naturales. Instituto y Museo de Ciencias Naturales; ArgentinaFil: Haro, Jose Augusto. Universidad Nacional de San Juan. Facultad de Ciencias Exactas, Fisicas y Naturales. Instituto y Museo de Ciencias Naturales; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Apaldetti, Graciela Cecilia. Universidad Nacional de San Juan. Facultad de Ciencias Exactas, Fisicas y Naturales. Instituto y Museo de Ciencias Naturales; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin

    Are chimpanzees really so poor at understanding imperative pointing? Some new data and an alternative view of canine and ape social cognition

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    There is considerable interest in comparative research on different species’ abilities to respond to human communicative cues such as gaze and pointing. It has been reported that some canines perform significantly better than monkeys and apes on tasks requiring the comprehension of either declarative or imperative pointing and these differences have been attributed to domestication in dogs. Here we tested a sample of chimpanzees on a task requiring comprehension of an imperative request and show that, though there are considerable individual differences, the performance by the apes rival those reported in pet dogs. We suggest that small differences in methodology can have a pronounced influence on performance on these types of tasks. We further suggest that basic differences in subject sampling, subject recruitment and rearing experiences have resulted in a skewed representation of canine abilities compared to those of monkeys and apes

    The plight of the sense-making ape

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    This is a selective review of the published literature on object-choice tasks, where participants use directional cues to find hidden objects. This literature comprises the efforts of researchers to make sense of the sense-making capacities of our nearest living relatives. This chapter is written to highlight some nonsensical conclusions that frequently emerge from this research. The data suggest that when apes are given approximately the same sense-making opportunities as we provide our children, then they will easily make sense of our social signals. The ubiquity of nonsensical contemporary scientific claims to the effect that humans are essentially--or inherently--more capable than other great apes in the understanding of simple directional cues is, itself, a testament to the power of preconceived ideas on human perception

    CD34 marks angiogenic tip cells in human vascular endothelial cell cultures

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    The functional shift of quiescent endothelial cells into tip cells that migrate and stalk cells that proliferate is a key event during sprouting angiogenesis. We previously showed that the sialomucin CD34 is expressed in a small subset of cultured endothelial cells and that these cells extend filopodia: a hallmark of tip cells in vivo. In the present study, we characterized endothelial cells expressing CD34 in endothelial monolayers in vitro. We found that CD34-positive human umbilical vein endothelial cells show low proliferation activity and increased mRNA expression of all known tip cell markers, as compared to CD34-negative cells. Genome-wide mRNA profiling analysis of CD34-positive endothelial cells demonstrated enrichment for biological functions related to angiogenesis and migration, whereas CD34-negative cells were enriched for functions related to proliferation. In addition, we found an increase or decrease of CD34-positive cells in vitro upon exposure to stimuli that enhance or limit the number of tip cells in vivo, respectively. Our findings suggest cells with virtually all known properties of tip cells are present in vascular endothelial cell cultures and that they can be isolated based on expression of CD34. This novel strategy may open alternative avenues for future studies of molecular processes and functions in tip cells in angiogenesis
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