4,802 research outputs found

    Splicing of concurrent upper-body motion spaces with locomotion

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    In this paper, we present a motion splicing technique for generating concurrent upper-body actions occurring simultaneously with the evolution of a lower-body locomotion sequence. Specifically, we show that a layered interpolation motion model generates upper-body poses while assigning different actions to each upper-body part. Hence, in the proposed motion splicing approach, it is possible to increase the number of generated motions as well as the number of desired actions that can be performed by virtual characters. Additionally, we propose an iterative motion blending solution, inverse pseudo-blending, to maintain a smooth and natural interaction between the virtual character and the virtual environment; inverse pseudo-blending is a constraint-based motion editing technique that blends the motions enclosed in a tetrahedron by minimising the distances between the end-effector positions of the actual and blended motions. Additionally, to evaluate the proposed solution, we implemented an example-based application for interactive motion splicing based on specified constraints. Finally, the generated results show that the proposed solution can be beneficially applied to interactive applications where concurrent actions of the upper-body are desired

    The Complexity of the Homotopy Method, Equilibrium Selection, and Lemke-Howson Solutions

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    We show that the widely used homotopy method for solving fixpoint problems, as well as the Harsanyi-Selten equilibrium selection process for games, are PSPACE-complete to implement. Extending our result for the Harsanyi-Selten process, we show that several other homotopy-based algorithms for finding equilibria of games are also PSPACE-complete to implement. A further application of our techniques yields the result that it is PSPACE-complete to compute any of the equilibria that could be found via the classical Lemke-Howson algorithm, a complexity-theoretic strengthening of the result in [Savani and von Stengel]. These results show that our techniques can be widely applied and suggest that the PSPACE-completeness of implementing homotopy methods is a general principle.Comment: 23 pages, 1 figure; to appear in FOCS 2011 conferenc

    Self-tuning and the derivation of the Fab Four

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    We have recently proposed a special class of scalar tensor theories known as the Fab Four. These arose from attempts to analyse the cosmological constant problem within the context of Horndeski's most general scalar tensor theory. The Fab Four together give rise to a model of self-tuning, with the relevant solutions evading Weinberg's no-go theorem by relaxing the condition of Poincare invariance in the scalar sector. The Fab Four are made up of four geometric terms in the action with each term containing a free potential function of the scalar field. In this paper we rigorously derive this model from the general model of Horndeski, proving that the Fab Four represents the only classical scalar tensor theory of this type that has any hope of tackling the cosmological constant problem. We present the full equations of motion for this theory, and give an heuristic argument to suggest that one might be able to keep radiative corrections under control. We also give the Fab Four in terms of the potentials presented in Deffayet et al's version of Horndeski.Comment: 25 pages, 1 figur

    Rethinking shortest path: an energy expenditure approach

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    Considering that humans acting in constrained environments do not always plan according to shortest path criteria; rather, they conceptually measure the path which minimises the amount of expended energy. Hence, virtual characters should be able to execute their paths according to planning methods based not on path length but on the minimisation of actual expended energy. Thus, in this paper, we introduce a simple method that uses a formula for computing vanadium dioxide (VO2) levels, which is a proxy for the energy expended by humans during various activities

    Setting up a rapid diagnostic clinic for patients with vague symptoms of cancer: a mixed method process evaluation study

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    Background The study sought to evaluate the impact of a Rapid Diagnostic Clinic (RDC) service designed to improve general practitioner (GP) referral processes for patients who do not meet existing referral criteria yet present with vague - but potentially concerning - symptoms of cancer. We sought to investigate how well the RDC has performed in the views of local GPs and patients, and through analysis of its activity and performance in the first two years of operation.MethodsThe study setting was a single, hospital-based RDC clinic in a University Health Board in South Wales. We used a mixed-method process evaluation study, including routinely collected activity and diagnosis data. All GPs were invited to participate in an online survey (34/165 responded), and a smaller group (n = 8) were interviewed individually. Two focus groups with patients and their carers (n = 7) provided in-depth personal accounts of their experiences.ResultsThe focus groups revealed high rates of patient satisfaction with the RDC. GPs were also overwhelmingly positive about the value of the RDC to their practice. There were 574 clinic attendances between July 2017 and March 2019; the mean age of attendees was 68, 57% were female, and approximately 30% had three or more vague symptoms. Of those attending, we estimated between 42 to 71 (7.3% and 12.3%) received preliminary cancer diagnoses. Median time from GP referral to RDC appointment was 12 days; from GP referral to cancer diagnosis was 34 days. Overall, 73% of RDC patients received either a new diagnosis (suspected cancer 23.2%, non-cancer 35.9%) or an onward referral to secondary care for further investigation with no new diagnosis (13.9%), and 27% were referred to primary care with no new diagnosis.ConclusionsThe RDC appears to enable a good patient experience in cancer diagnosis. Patients are seen in timely fashion, and the service is highly regarded by them, their carers, and referring GPs. Although too early to draw conclusions about long-term patient outcomes, there are strong indications to suggest that this model of service provision can set higher standards for a strongly patient-centred service. <br/

    Origin of modulated phases and magnetic hysteresis in TmB_4

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    We investigate the low temperature magnetic phases in TmB_4, a metallic quantum magnet on the geometrically frustrated Shastry-Sutherland lattice, using co-ordinated experimental and theoretical studies. Our results provide an explanation for the appearance of the intriguing fractional plateau in TmB_4 and accompanying magnetic hysteresis. Together with observation of the bump in the half-plateau, our results support the picture that the magnetization plateau structure in TmB_4 is strongly influenced by the zero-field modulated phases. We present a phenomenological model to explain the appearance of the modulated phases and a microscopic Hamiltonian that captures the complete magnetic behavior of TmB_4.Comment: 7 pages, 5 figure

    Hysteretic magnetoresistance and unconventional anomalous Hall effect in the frustrated magnet TmB_4

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    We study TmB_4, a frustrated magnet on the Archimedean Shastry-Sutherland lattice, through magnetization and transport experiments. The lack of anisotropy in resistivity shows that TmB_4 is an electronically three-dimensional system. The magnetoresistance (MR) is hysteretic at low-temperature even though a corresponding hysteresis in magnetization is absent. The Hall resistivity shows unconventional anomalous Hall effect (AHE) and is linear above saturation despite a large MR. We propose that complex structures at magnetic domain walls may be responsible for the hysteretic MR and may also lead to the AHE

    Sequential epiretinal membrane removal with internal limiting membrane peeling in brilliant blue G-assisted macular surgery

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    Purpose To assess the selectivity of brilliant blue G (BBG) staining by analysing the morphological components of unstained and stained tissue obtained during epiretinal membrane (ERM) removal with internal limiting membrane (ILM) peeling in BBG-assisted macular surgery. Methods Twenty-six surgical specimens were removed from 13 eyes with epiretinal gliosis during vitrectomy using BBG for ERM and ILM peeling. We included eyes with idiopathic macular pucker, idiopathic macular hole and vitreomacular traction syndrome. The dye was injected into the fluid-filled globe. Unstained and stained epiretinal tissue was harvested consecutively and placed into separate containers. All specimens were processed for conventional transmission electron microscopy. Results The first surgical specimen of all eyes showed no intraoperative staining with BBG and corresponded to masses of cells and collagen. The second surgical specimen demonstrated good staining characteristics and corresponded to the ILM in all patients included. In seven eyes, the ILM specimens were seen with minor cell proliferations such as single cells or a monolayer of cells. Myofibroblasts, fibroblasts and astrocytes were present. In five cases, native vitreous collagen fibrils were found at the ILM. In six of the eyes, ILM specimens were blank. Conclusion Our clinicopathological correlation underlines the selective staining properties of BBG. The residual ILM is selectively stained by BBG even when a small amount of cells and collagen adheres to its vitreal side. To reduce the retinal exposure to the dye, the surgeon might choose to remove the ERM without using the dye, followed by a BBG injection to identify residual ILM

    Deubiquitinating enzymes at the crossroads of lipid metabolism and cancer

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    Deregulated lipid metabolism has been recognized as a critical alteration that supports the development and growth of various types of tumors. Changes in lipid metabolism enable reprogramming of energetics and availability of synthetic intermediates and signaling mediators that can have pleiotropic effects in cellular physiology. The identification of critical factors that reshape lipid metabolism during oncogenesis can provide targets for the development of novel therapeutic protocols. Enzymes are an attractive class of molecules for the development of therapeutic compounds. This review focuses on deubiquitinating enzymes (DUBs) that have been implicated both in lipid and cellular homeostatic processes. In certain cases, a causative link between the two processes is mediated by the deubiquitinating enzyme whereas in other cases we present evidence that support a possible role for the DUB as the underlying linker of lipid content and cell growth deregulation. Collectively, our report highlights critical nodes of deubiquitination-dependent metabolic and growth regulatory processes that can be interrogated further for a detailed understanding of cancer promoting mechanisms and therapeutic exploitation
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