2,111 research outputs found

    On the Validity of the 0-1 Test for Chaos

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    In this paper, we present a theoretical justification of the 0-1 test for chaos. In particular, we show that with probability one, the test yields 0 for periodic and quasiperiodic dynamics, and 1 for sufficiently chaotic dynamics

    Considering the impact of situation-specific motivations and constraints in the design of naturally ventilated and hybrid buildings

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    A simple logical model of the interaction between a building and its occupants is presented based on the principle that if free to do so, people will adjust their posture, clothing or available building controls (windows, blinds, doors, fans, and thermostats) with the aim of achieving or restoring comfort and reducing discomfort. These adjustments are related to building design in two ways: first the freedom to adjust depends on the availability and ease-of-use of control options; second the use of controls affects building comfort and energy performance. Hence it is essential that these interactions are considered in the design process. The model captures occupant use of controls in response to thermal stimuli (too warm, too cold etc.) and non-thermal stimuli (e.g. desire for fresh air). The situation-specific motivations and constraints on control use are represented through trigger temperatures at which control actions occur, motivations are included as negative constraints and incorporated into a single constraint value describing the specifics of each situation. The values of constraints are quantified for a range of existing buildings in Europe and Pakistan. The integration of the model within a design flow is proposed and the impact of different levels of constraints demonstrated. It is proposed that to minimise energy use and maximise comfort in naturally ventilated and hybrid buildings the designer should take the following steps: 1. Provide unconstrained low energy adaptive control options where possible, 2. Avoid problems with indoor air quality which provide motivations for excessive ventilation rates, 3. Incorporate situation-specific adaptive behaviour of occupants in design simulations, 4. Analyse the robustness of designs against variations in patterns of use and climate, and 5. Incorporate appropriate comfort standards into the operational building controls (e.g. BEMS)

    Submission in Response to the Australian Productivity Commission's Inquiry into IP Arrangements Draft Report

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    This Submission by nine intellectual property academics responds to the Draft Report in the Inquiry into IP Arrangements published by the Australian Productivity Commission on 29 April 2016 ('Draft Report'). In broad terms, the submission supports many of the goals of, and recommendations of, the Productivity Commission expressed in the Draft Report, but expresses concerns that some recommendations may not achieve the overall goals of the Commission, or reflect misunderstandings of the statutory framework. The submission addresses many of the Commission's draft recommendations concerning copyright, patents, trade marks and geographical indicators, IP and public institutions, and IP's institutional and governance arrangements

    Anisotropic thermodynamics of d-wave superconductors in the vortex state

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    We show that the density of states and the thermodynamic properties of a 2D d-wave superconductor in the vortex state with applied magnetic field H\bf H in the plane depend on the angle between H\bf H and the order parameter nodes. Within a semiclassical treatment of the extended quasiparticle states, we obtain fourfold oscillations of the specific heat, measurement of which provides a simple probe of gap symmetry. The frequency dependence of the density of states and the temperature dependence of thermodynamic properties obey different power laws for field in the nodal and anti-nodal direction. The fourfold pattern is changed to twofold when orthorhombicity is considered.Comment: 5 pages, figures included, minor changes, published versio

    On the universal AC optical background in graphene

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    The latest experiments have confirmed the theoretically expected universal value πe2/2h\pi e^2/2h of the ac conductivity of graphene and have revealed departures of the quasiparticle dynamics from predictions for the Dirac fermions in idealized graphene. We present analytical expressions for the ac conductivity in graphene which allow one to study how it is affected by interactions, temperature, external magnetic field and the opening of a gap in the quasiparticle spectrum. We show that the ac conductivity of graphene does not necessarily give a metrologically accurate value of the von Klitzing constant h/e2h/e^2, because it is depleted by the electron-phonon interaction. In a weak magnetic field the ac conductivity oscillates around the universal value and the Drude peak evolves into a peak at the cyclotron frequency.Comment: 18 pages, 4 figures; v2: to match New J. Phys. (Focus on Graphene issue

    Two-years Postradiotherapy Biopsies: Lessons from MRC RT01 Trial

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    Background: The importance of 2-yr postradiotherapy prostate biopsy status remains uncertain. Objective: To assess the value of 2 year post treatment biopsies in a randomised trial of radiotherapy dose escalation. Design, setting, and participants: Between 1998 and 2001, 843 men with localised prostate cancer were randomised to receive either control-64 Gy or escalated-74 Gy conformal radiotherapy (CFRT) in the MRC RT01 trial in combination with 3–6-mo neoadjuvant androgen deprivation therapy. Prostate biopsies were planned at 2 yr from start of CFRT in suitable men. Outcome measurements and statistical analysis: Prostate biopsy results and prostate-specific antigen (PSA) levels performed at 2 yr post-CFRT were evaluated with long-term biochemical progression free survival (bPFS) and overall survival. Outcome measures were timed from the 2-yr biopsy using a landmark approach. Results and limitations: A 2-yr biopsy was performed in 312/843 patients. One hundred and seventy-seven patients were included in the per-protocol group with median follow-up of 7.8 yr from biopsy. Median PSA at biopsy was 0.5 ng/ml. Sixty-four bPFS events were reported: 46/145 (32%) in patients with negative, 6/18 (33%) suspicious, and 12/14 (86%) positive biopsies. A positive biopsy was prognostic of worse bPFS, going forward, compared with negative and suspicious biopsies, hazard ratio (HR) = 4.81 (95% confidence interval [CI]: 2.50–9.26, p < 0.001). The estimate for survival was HR = 1.58 (95% CI: 0.52–4.78, p = 0.42). PSA values at 2 yr between 1.01 ng/ml and 2.09 ng/ml were also associated with subsequent PSA failures (HR = 2.71, 95% CI: 1.98–3.71), bPFS events (HR = 2.45, 95% CI: 1.81–3.32), and prostate cancer-specific survival (HR = 2.87, 95% CI: 1.08–7.64) compared with PSA ≤1.0 ng/ml. Conclusions: Two-year postradiotherapy prostate biopsies have limited value in patients with PSA control but both positive biopsy and higher PSA status are strongly associated with future bPFS events. A policy of selected biopsy may provide an opportunity for early salvage interventions. Patient summary: Routine 2-yr postradiotherapy biopsy is not recommended but can be considered in selected patients with unfavourable post-treatment prostate-specific antigen levels who are suitable for early salvage treatments

    Temporal sampling helps unravel the genetic structure of naturally occurring populations of a phytoparasitic nematode. 1. Insights from the estimation of effective population sizes

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    International audienceThe sustainability of modern agriculture relies on strategies that can control the ability of pathogens to overcome chemicals or genetic resistances through natural selection. This evolutionary potential, which depends partly on effective population size (Ne), is greatly influenced by human activities. In this context, wild pathogen populations can provide valuable information for assessing the long-term risk associated with crop pests. In this study, we estimated the effective population size of the beet cyst nematode, Heterodera schachtii, by sampling 34 populations infecting the sea beet Beta vulgaris spp. maritima twice within a one-year period. Only 20 populations produced enough generations to analyze the variation in allele frequencies, with the remaining populations showing a high mortality rate of the host plant after only one year. The 20 analyzed populations showed surprisingly low effective population sizes, with most having Ne close to 85 individuals. We attribute these low values to the variation in population size through time, systematic inbreeding, and unbalanced sex- ratios. Our results suggest that H. schachtii has low evolutionary potential in natural environments. Pest control strategies in which populations on crops mimic wild populations may help prevent parasite adaptation to host resistance

    High-pressure structural, elastic and electronic properties of the scintillator host material, KMgF_3

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    The high-pressure structural behaviour of the fluoroperovskite KMgF_3 is investigated by theory and experiment. Density functional calculations were performed within the local density approximation and the generalized gradient approximation for exchange and correlation effects, as implemented within the full-potential linear muffin-tin orbital method. In situ high-pressure powder x-ray diffraction experiments were performed up to a maximum pressure of 40 GPa using synchrotron radiation. We find that the cubic Pm\bar{3}m crystal symmetry persists throughout the pressure range studied. The calculated ground state properties -- the equilibrium lattice constant, bulk modulus and elastic constants -- are in good agreement with experimental results. By analyzing the ratio between the bulk and shear modulii, we conclude that KMgF_3 is brittle in nature. Under ambient conditions, KMgF_3 is found to be an indirect gap insulator with the gap increasing under pressure.Comment: 4 figure
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