780 research outputs found

    Post-Turing Methodology: Breaking the Wall on the Way to Artificial General Intelligence

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    This article offers comprehensive criticism of the Turing test and develops quality criteria for new artificial general intelligence (AGI) assessment tests. It is shown that the prerequisites A. Turing drew upon when reducing personality and human consciousness to ā€œsuitable branches of thoughtā€ re-flected the engineering level of his time. In fact, the Turing ā€œimitation gameā€ employed only symbolic communication and ignored the physical world. This paper suggests that by restricting thinking ability to symbolic systems alone Turing unknowingly constructed ā€œthe wallā€ that excludes any possi-bility of transition from a complex observable phenomenon to an abstract image or concept. It is, therefore, sensible to factor in new requirements for AI (artificial intelligence) maturity assessment when approaching the Tu-ring test. Such AI must support all forms of communication with a human being, and it should be able to comprehend abstract images and specify con-cepts as well as participate in social practices

    Multiple essential functions of Plasmodium falciparum actin-1 during malaria blood-stage development

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    Background: The phylum Apicomplexa includes intracellular parasites causing immense global disease burden, the deadliest of them being the human malaria parasite Plasmodium falciparum, which invades and replicates within erythrocytes. The cytoskeletal protein actin is well conserved within apicomplexans but divergent from mammalian actins, and was primarily reported to function during host cell invasion. However, novel invasion mechanisms have been described for several apicomplexans, and specific functions of the acto-myosin system are being reinvestigated. Of the two actin genes in P. falciparum, actin-1 (pfact1) is ubiquitously expressed in all life-cycle stages and is thought to be required for erythrocyte invasion, although its functions during parasite development are unknown, and definitive in vivo characterisation during invasion is lacking. Results: Here we have used a conditional Cre-lox system to investigate the functions of PfACT1 during P. falciparum bloodstage development and host cell invasion. We demonstrate that PfACT1 is crucially required for segregation of the plastid-like organelle, the apicoplast, and for efficient daughter cell separation during the final stages of cytokinesis. Surprisingly, we observe that egress from the host cell is not an actin-dependent process. Finally, we show that parasites lacking PfACT1 are capable of microneme secretion, attachment and formation of a junction with the erythrocyte, but are incapable of host cell invasion. Conclusions: This study provides important mechanistic insights into the definitive essential functions of PfACT1 in P. falciparum, which are not only of biological interest, but owing to functional divergence from mammalian actins, could also form the basis for the development of novel therapeutics against apicomplexans

    Extracellular matrix components modulate different stages in Ī²2-microglobulin amyloid formation.

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    Amyloid deposition of wild-type human Ī²2-microglobulin (WT-hĪ²2m) in the joints of long-term hemodialysis patients is the hallmark of dialysis-related amyloidosis (DRA). In vitro, WT-hĪ²2m does not form amyloid fibrils at physiological pH and temperature unless co-solvents or other reagents are added. Therefore, understanding how fibril formation is initiated and maintained in the joint space is important for elucidating WT-hĪ²2m aggregation and DRA onset. Here, we investigated the roles of collagen I and the commonly administered anticoagulant, low-molecular-weight (LMW) heparin, in the initiation and subsequent aggregation phases of WT-hĪ²2m in physiologically relevant conditions. Using thioflavin T (ThT) fluorescence to study the kinetics of amyloid formation, we analyzed how these two agents affect specific stages of WT-hĪ²2m assembly. Our results revealed that LMW-heparin strongly promotes WT-hĪ²2m fibrillogenesis during all stages of aggregation. However, collagen I affected WT-hĪ²2m amyloid formation in contrasting ways: decreasing the lag time of fibril formation in the presence of LMW-heparin and slowing the rate at higher concentrations. We found that in self-seeded reactions, interaction of collagen I with WT-hĪ²2m amyloid fibrils attenuates surface-mediated growth of WT-hĪ²2m fibrils, demonstrating a key role of secondary nucleation in WT-hĪ²2m amyloid formation. Interestingly, collagen I fibrils did not suppress surface-mediated assembly of WT-hĪ²2m monomers when cross-seeded with fibrils formed from the N-terminally truncated variant Ī”N6-hĪ²2m. Together, these results provide detailed insights into how collagen I and LMW-heparin impact different stages in the aggregation of WT-hĪ²2m into amyloid which lead to dramatic effects on the time course of assembly

    Collagen I weakly interacts with the Ī²-sheets of Ī²2-microglobulin and enhances conformational exchange to induce amyloid formation

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    Amyloidogenesis is significant in both protein function and pathology. Amyloid formation of folded, globular proteins is commonly initiated by partial or complete unfolding. However, how this unfolding event is triggered for proteins that are otherwise stable in their native environments is not well understood. The accumulation of the immunoglobulin protein Ī²2-microglobulin (Ī²2m) into amyloid plaques in the joints of long-term hemodialysis patients is the hallmark of Dialysis Related Amyloidosis (DRA). While Ī²2m does not form amyloid unassisted near neutral pH in vitro, the localization of Ī²2m deposits to joint spaces suggests a role for the local extracellular matrix (ECM) proteins, specifically collagens, in promoting amyloid formation. Indeed, collagen and other ECM components have been observed to facilitate Ī²2m amyloid formation, but the large size and anisotropy of the complex, combined with the low affinity of these interactions, has limited atomic-level elucidation of the amyloid-promoting mechanism(s) by these molecules. Using solution NMR approaches that uniquely probe weak interactions in large molecular weight complexes, we are able to map the binding interfaces on Ī²2m for collagen I and detect collagen I-induced Ī¼sā€“ms timescale dynamics in the Ī²2m backbone. By combining solution NMR relaxation methods and 15N-dark state exchange saturation transfer experiments, we propose a model in which weak, multimodal collagen Iā€“Ī²2m interactions promote exchange with a minor population of amyloid-competent species to induce fibrillogenesis. The results portray the intimate role of the environment in switching an innocuous protein into an amyloid-competent state, rationalizing the localization of amyloid deposits in DRA

    Chemical pavement modifications to reduce ice adhesion

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    The formation of ice and snow on road pavement surfaces is a recurring problem, creating hazardous driving conditions, restricting public mobility as well as having adverse economic effects. It would be desirable to develop new and improved ways of modifying the pavement surface, to prevent or at least delay the build-up of ice and to weaken the pavementā€“ice bond, and making the ice which forms easier to remove. This development could lead to economic, environmental and safety benefits for winter service providers and road users. This paper describes how environmental scanning electron microscopy was used to examine the mechanism by which de-icing chemicals, added as a filler replacement to bituminous materials, can be transferred to the pavement surface. The paper assesses the potential for chemical modifications to reduce the adhesion between ice and the pavement surface by means of work of adhesion calculations, based on surface energy parameters and a new physical ice bond test. The paper also examines the influence that the chemical modifications have on the durability of the pavement surface course

    Building social capital through breastfeeding peer support: Insights from an evaluation of a voluntary breastfeeding peer support service in North-West England

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    Background: Peer support is reported to be a key method to help build social capital in communities. To date there are no studies that describe how this can be achieved through a breastfeeding peer support service. In this paper we present findings from an evaluation of a voluntary model of breastfeeding peer support in North-West England to describe how the service was operationalized and embedded into the community. This study was undertaken from May, 2012 to May, 2013. Methods: Interviews (group or individual) were held with 87 participants: 24 breastfeeding women, 13 peer supporters and 50 health and community professionals. The data contained within 23 monthly monitoring reports (January, 2011 to February 2013) compiled by the voluntary peer support service were also extracted and analysed. Results: Thematic analysis was undertaken using social capital concepts as a theoretical lens. Key findings were identified to resonate with ā€™bondingā€™, ā€˜bridgingā€™ and ā€˜linkingā€™ forms of social capital. These insights illuminate how the peer support service facilitates ā€˜bondsā€™ with its members, and within and between women who access the service; how the service ā€˜bridgesā€™ with individuals from different interests and backgrounds, and how ā€˜linksā€™ were forged with those in authority to gain access and reach to women and to promote a breastfeeding culture. Some of the tensions highlighted within the social capital literature were also identified. Conclusions: Horizontal and vertical relationships forged between the peer support service and community members enabled peer support to be embedded into care pathways, helped to promote positive attitudes to breastfeeding and to disseminate knowledge and maximise reach for breastfeeding support across the community. Further effort to engage with those of different ethnic backgrounds and to resolve tensions between peer supporters and health professionals is warranted
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