629 research outputs found

    Response to comments on "Differential Sensitivity to Human Communication in Dogs, Wolves, and Human Infants."

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    The comments by Fiset and Marshall-Pescini et al. raise important methodological issues and propose alternative accounts for our finding of perseverative search errors in dogs. Not denying that attentional processes and local enhancement are involved in such object search tasks, we provide here new evidence and argue that dogs’ behavior is affected by a combination of factors, including specific susceptibility to human communicative signals

    Nanomechanical Characterization of Osteogenic Differentiation of Mesenchymal Stem Cells on Bioactive Peptide Nanofiber Hydrogels

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    Stem cell differentiation is known to be influenced by the mechanical properties of the surrounding extracellular matrix (ECM); however, little is known about the mechanical phenotypes of differentiating stem cells within the ECM. Here, this study uses osteoinductive, ECM-mimetic peptide nanofibers to investigate the changes in the mechanical properties of rat mesenchymal stem cells (rMSCs) during osteogenic differentiation. In addition, octafluorocyclobutane (C4F8)-coated atomic force microscopy (AFM) cantilevers are developed to minimize tip–sample adhesion during the nanomechanical characterization of rMSCs, and osteogenic differentiation is monitored through molecular analysis in conjunction with AFM measurements. rMSCs cultured on osteoinductive peptide nanofibers differentiate at substantially higher rates, form osteogenic cell clusters, deposit calcium to the surrounding matrix, and strikingly increase their Young's moduli throughout the osteogenic differentiation process compared to controls. These results show that the elasticity profiles of differentiating rMSCs may change significantly depending on environmental factors and especially the degree of biomineralization, and that the natural elasticity responses of cells cultured on scaffolds may be considerably different from those observed on non-bioactive surfaces. This is important for the identification of cell elasticity as a biophysical marker of osteogenic differentiation of MSCs, and indicates that biomineralization might have a predominant role on cell mechanics. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinhei

    Exploiting Native Al2O3 for Multispectral Aluminum Plasmonics

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    Aluminum, despite its abundance and low cost, is usually avoided for plasmonic applications due to losses in visible/infrared regimes and its interband absorption at 800 nm. Yet, it is compatible with silicon CMOS processes, making it a promising alternative for integrated plasmonic applications. It is also well known that a thin layer of native Al2O3 is formed on aluminum when exposed to air, which must be taken into account properly while designing plasmonic structures. Here, for the first time we report exploitation of the native Al2O3 layer for fabrication of periodic metal-insulator-metal (MIM) plasmonic structures that exhibit resonances spanning a wide spectral range, from the near-ultraviolet to mid-infrared region of the spectrum. Through fabrication of silver nanoislands on aluminum surfaces and MIM plasmonic surfaces with a thin native Al2O3 layer, hierarchical plasmonic structures are formed and used in surface-enhanced infrared spectroscopy (SEIRA) and surface-enhanced Raman spectrocopy (SERS) for detection of self-assembled monolayers of dodecanethiol. (Chemical Equation Presented). © 2014 American Chemical Society

    Anisotropy of mechanical properties of pinctada margaritifera mollusk shell

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    The mechanical properties such as compressive strength and nanohardness were investigated for Pinctada margaritifera mollusk shells. The compressive strength was evaluated through a uniaxial static compression test performed along the load directions parallel and perpendicular to the shell axis, respectively, while the hardness and Young modulus were measured using nanoindentation. In order to observe the crack propagation, for the first time for such material, the in-situ X-ray microscopy (nano-XCT) imaging (together with 3D reconstruction based on the acquired images) during the indentation tests was performed. The results were compared with these obtained during the micro-indentation test done with the help of conventional Vickers indenter and subsequent scanning electron microscopy observations. The results revealed that the cracks formed during the indentation start to propagate in the calcite prism until they reach a ductile organic matrix where most of them are stopped. The obtained results confirm a strong anisotropy of both crack propagation and the mechanical strength caused by the formation of the prismatic structure in the outer layer of P. margaritifera shell.The research was co-financed by the European Union from the resources of the European Social Fund (Project No.WND-POWR.03.02.00-00-I043/16), the DAAD program. A.C. acknowledges project CGL2017-85118-P of the Spanish Ministerio de Ciencia e Innovación for funding

    Do Dogs (Canis lupus familiaris) Make Counterproductive Choices Because They Are Sensitive to Human Ostensive Cues?

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    Dogs appear to be sensitive to human ostensive communicative cues in a variety of situations, however there is still a measure of controversy as to the way in which these cues influence human-dog interactions. There is evidence for instance that dogs can be led into making evaluation errors in a quantity discrimination task, for example losing their preference for a larger food quantity if a human shows a preference for a smaller one, yet there is, so far, no explanation for this phenomenon. Using a modified version of this task, in the current study we investigated whether non-social, social or communicative cues (alone or in combination) cause dogs to go against their preference for the larger food quantity. Results show that dogs' evaluation errors are indeed caused by a social bias, but, somewhat contrary to previous studies, they highlight the potent effect of stimulus enhancement (handling the target) in influencing the dogs' response. A mild influence on the dog's behaviour was found only when different ostensive cues (and no handling of the target) were used in combination, suggesting their cumulative effect. The discussion addresses possible motives for discrepancies with previous studies suggesting that both the intentionality and the directionality of the action may be important in causing dogs' social biases

    Fabrication of Supramolecular n/p-Nanowires via Coassembly of Oppositely Charged Peptide-Chromophore Systems in Aqueous Media

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    Fabrication of supramolecular electroactive materials at the nanoscale with well-defined size, shape, composition, and organization in aqueous medium is a current challenge. Herein we report construction of supramolecular charge-transfer complex one-dimensional (1D) nanowires consisting of highly ordered mixed-stack π-electron donor-acceptor (D-A) domains. We synthesized n-type and p-type β-sheet forming short peptide-chromophore conjugates, which assemble separately into well-ordered nanofibers in aqueous media. These complementary p-type and n-type nanofibers coassemble via hydrogen bonding, charge-transfer complex, and electrostatic interactions to generate highly uniform supramolecular n/p-coassembled 1D nanowires. This molecular design ensures highly ordered arrangement of D-A stacks within n/p-coassembled supramolecular nanowires. The supramolecular n/p-coassembled nanowires were found to be formed by A-D-A unit cells having an association constant (KA) of 5.18 × 105 M-1. In addition, electrical measurements revealed that supramolecular n/p-coassembled nanowires are approximately 2400 and 10 times more conductive than individual n-type and p-type nanofibers, respectively. This facile strategy allows fabrication of well-defined supramolecular electroactive nanomaterials in aqueous media, which can find a variety of applications in optoelectronics, photovoltaics, organic chromophore arrays, and bioelectronics. © 2017 American Chemical Society

    A new generic open pit mine planning process with risk assessment ability

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    Conventionally, mining industry relies on a deterministic view, where a unique mine plan is determined based on a single resource model. A major shortfall of this approach is the inability to assess the risk caused by the well-known geological uncertainty, i.e. the in situ grade and tonnage variability of the mineral deposit. Despite some recent attempts in developing stochastic mine planning models which have demonstrated promising results, the industry still remains sceptical about this innovative idea. With respect to unbiased linear estimation, kriging is the most popular and reliable deterministic interpolation technique for resource estimation and it appears to remain its popularity in the near future. This paper presents a new systematic framework to quantify the risk of kriging-based mining projects due to the geological uncertainties. Firstly, conditional simulation is implemented to generate a series of equally-probable orebody realisations and these realisations are then compared with the kriged resource model to analyse its geological uncertainty. Secondly, a production schedule over the life of mine is determined based on the kriged resource model. Finally, risk profiles of that production schedule, namely ore and waste tonnage production, blending grade and Net Present Value (NPV), are constructed using the orebody realisations. The proposed model was applied on a multi-element deposit and the result demonstrates that that the kriging-based mine plan is unlikely to meet the production targets. Especially, the kriging-based mine plan overestimated the expected NPV at a magnitude of 6.70% to 7.34% (135 Mto151 M to 151 M). A new multivariate conditional simulation framework was also introduced in this paper to cope with the multivariate nature of the deposit. Although an iron ore deposit is used to prove the concepts, the method can easily be adapted to other kinds of mineral deposits, including surface coal mine

    Textiloma: a case of foreign body mimicking a spinal mass

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    Items such as cotton or gauze pads can be mistakenly left behind during operations. Such foreign materials (called textilomas or gossypibomas) cause foreign body reaction in the surrounding tissue. The complications caused by these foreign bodies are well known, but cases are rarely published because of medico-legal implications. Some textilomas cause infection or abscess formation in the early stage, whereas others remain clinically silent for many years. Here, we describe a case of textiloma in which the patient presented with low-back pain 4 years after lumbar discectomy. Imaging revealed an abcess-like mass in the lumbar epidural space
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