689 research outputs found

    Application of various water soluble polymers in gas hydrate inhibition

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    Formation of hydrates in gas transmission lines due to high pressures and low temperatures is a serious problem in the oil and gas industry with potential hazards and/or economic losses. Kinetic hydrate inhibitors are water soluble polymeric compounds that prevent or delay hydrate formation. This review presents the various types of water soluble polymers used for hydrate inhibition, including conventional and novel polymeric inhibitors along with their limitations. The review covers the relevant properties of vinyl lactam, amide, dendrimeric, fluorinated, and natural biodegradable polymers. The factors affecting the performance of these polymers and the structure-property relationships are reviewed. A comprehensive review of the techniques used to evaluate the performance of the polymeric inhibitors is given. This review also addresses recent developments, current and future challenges, and field applications of a range of polymeric kinetic hydrate inhibitors. 2016 Elsevier Ltd. All rights reserved.This research is supported by Saudi Aramco through project # CPM 2297. Authors would like to thank the Center for Integrative Petroleum Research , King Fahd University of Petroleum & Minerals for supporting this research.Scopu

    Mentalizing the body: spatial and social cognition in anosognosia for hemiplegia

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    Following right-hemisphere damage, a specific disorder of motor awareness can occur called anosognosia for hemiplegia, i.e. the denial of motor deficits contralateral to a brain lesion. The study of anosognosia can offer unique insights into the neurocognitive basis of awareness. Typically, however, awareness is assessed as a first person judgement and the ability of patients to think about their bodies in more ‘objective’ (third person) terms is not directly assessed. This may be important as right-hemisphere spatial abilities may underlie our ability to take third person perspectives. This possibility was assessed for the first time in the present study. We investigated third person perspective taking using both visuospatial and verbal tasks in right-hemisphere stroke patients with anosognosia ( n = 15) and without anosognosia ( n = 15), as well as neurologically healthy control subjects ( n = 15). The anosognosic group performed worse than both control groups when having to perform the tasks from a third versus a first person perspective. Individual analysis further revealed a classical dissociation between most anosognosic patients and control subjects in mental (but not visuospatial) third person perspective taking abilities. Finally, the severity of unawareness in anosognosia patients was correlated to greater impairments in such third person, mental perspective taking abilities (but not visuospatial perspective taking). In voxel-based lesion mapping we also identified the lesion sites linked with such deficits, including some brain areas previously associated with inhibition, perspective taking and mentalizing, such as the inferior and middle frontal gyri, as well as the supramarginal and superior temporal gyri. These results suggest that neurocognitive deficits in mental perspective taking may contribute to anosognosia and provide novel insights regarding the relation between self-awareness and social cognition

    Testosterone administration in women increases the size of their peripersonal space

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    Peripersonal space (PPS) is the space immediately surrounding the body, conceptualised as a sensory-motor interface between body and environment. PPS size differs between individuals and contexts, with intrapersonal traits and states, as well as social factors having a determining role on the size of PPS. Testosterone plays an important role in regulating social-motivational behaviour and is known to enhance dominance motivation in an implicit and unconscious manner. We investigated whether the dominance-enhancing effects of testosterone reflect as changes in the representation of PPS in a within-subjects testosterone administration study in women (N = 19). Participants performed a visuo-tactile integration task in a mixed-reality setup. Results indicated that the administration of testosterone caused a significant enlargement of participants’ PPS, suggesting that testosterone caused participants to implicitly appropriate a larger space as their own. These findings suggest that the dominance-enhancing effects of testosterone reflect at the level of sensory-motor processing in PPS

    Toward Psycho-robots

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    We try to perform geometrization of psychology by representing mental states, >, by points of a metric space, >. Evolution of ideas is described by dynamical systems in metric mental space. We apply the mental space approach for modeling of flows of unconscious and conscious information in the human brain. In a series of models, Models 1-4, we consider cognitive systems with increasing complexity of psychological behavior determined by structure of flows of ideas. Since our models are in fact models of the AI-type, one immediately recognizes that they can be used for creation of AI-systems, which we call psycho-robots, exhibiting important elements of human psyche. Creation of such psycho-robots may be useful improvement of domestic robots. At the moment domestic robots are merely simple working devices (e.g. vacuum cleaners or lawn mowers) . However, in future one can expect demand in systems which be able not only perform simple work tasks, but would have elements of human self-developing psyche. Such AI-psyche could play an important role both in relations between psycho-robots and their owners as well as between psycho-robots. Since the presence of a huge numbers of psycho-complexes is an essential characteristic of human psychology, it would be interesting to model them in the AI-framework

    Landau-Ginzburg method applied to finite fermion systems: Pairing in Nuclei

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    Given the spectrum of a Hamiltonian, a methodology is developed which employs the Landau-Ginsburg method for characterizing phase transitions in infinite systems to identify phase transition remnants in finite fermion systems. As a first application of our appproach we discuss pairing in finite nuclei.Comment: 14 pages, 4 figure

    On the Degree of Team Cooperation in CD Grammar Systems.

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    In this paper, we introduce a dynamical complexity measure, namely the degree of team cooperation, in the aim of investigating "how much" the components of a grammar system cooperate when forming a team in the process of generating terminal words. We present several results which strongly suggest that this measure is trivial in the sense that the degree of team cooperation of any language is bounded by a constant. Finally, we prove that the degree of team cooperation of a given cooperating/distributed grammar system cannot be algorithmically computed and discuss a decision problem

    Remembering, imagining, false memories & personal meanings

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    The Self-Memory System encompasses the working self, autobiographical memory and episodic memory. Specific autobiographical memories are patterns of activation over knowledge structures in autobiographical and episodic memory brought about by the activating effect of cues. The working self can elaborate cues based on the knowledge they initially activate and so control the construction of memories of the past and the future. It is proposed that such construction takes place in the remembering–imagining system – a window of highly accessible recent memories and simulations of near future events. How this malfunctions in various disorders is considered as are the implication of what we term the modern view of human memory for notions of memory accuracy. We show how all memories are to some degree false and that the main role of memories lies in generating personal meanings

    Drafting a composite indicator of validity for regulatory models and legal systems

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    The aim of this paper is to lay the groundwork for the creation of a composite indicator of the validity of regulatory systems. The composite nature of the indicator implies a) that its construction is embedded in the long-standing theoretical debate and framework of legal validity; b) that it formally contains other sub-indicators whose occurrence is essential to the determination of validity. The paper suggests, in other words, that validity is a second-degree property, i.e., one that occurs only once the justice, efficiency, effectiveness, and enforceability of the system have been checked

    A Neuropsychoanalytical approach to the hard problem of consciousness

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    A neuropsychoanalytical approach to the ‘hard problem’ of consciousness revolves around the distinction between the subject and objects of consciousness. In contrast to the mainstream of cognitive science, neuropsychoanalysis prioritises the subject. The subject of consciousness is the indispensable page upon which its objects are inscribed. This has implications for our conception of the mental. The subjective being of consciousness is not registered in the classical exteroceptive modalities; it is not a cognitive representation, not a memory trace. Cognitive representations are ‘mental solids,’ embedded within subjective consciousness, and their tangible and visible (etc.) properties are projected onto reality. It is important to recognise that mental solids (e.g. the body-as-object) are no more real than the subjective being they are represented in (the body-as-subject). Moreover, pure subjectivity is not without content or quality. This aspect of consciousness is conventionally described quantitatively as the level of consciousness, ‘wakefulness’. But it feels like something to be awake. The primary modality of this aspect of consciousness is affect. Some implications of this frame of reference are discussed here, in broad brush strokes. This is an electronic version of an article published as Journal of Integrative Neuroscience, Volume 13, Issue 2, 2014, pp. 173-185. DOI: http://dx.doi.org/10.1142/S0219635214400032, © World Scientific Publishing Company, http://www.worldscientific.com/worldscinet/jin
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