Charge-Inhomogeneity doping relations in YBCO detected by Angle Dependent Nuclear Quadrupole Resonance

The origin of charge inhomogeneity in YBa_{2}Cu_{3}O_{y} is investigated using a new experimental method designed to determine the nuclear quadrupole resonance (NQR) asymmetry parameter eta for very wide NQR lines at different positions on the line. The method is based on the measurement of the echo intensity as a function of the angle between the radio frequency field H1 and the principal axis of the electric field gradient. Static charge inhomogeneity deduced from eta>0 are found in this compound, but only in conjunction with oxygen deficiency. This limits considerably the possible forms of charge inhomogeneity in bulk YBa_{2}Cu_{3}O_{y}.Comment: To be published in Phys. Rev. B; Revised version with a correction to figure

Are experienced drivers more likely than novice drivers to benefit from driving simulations with a wide field of view?

This study aimed to further our understanding of the impact of a restricted field of view on visual search and hazard perception, by comparing novice and experienced driver performance in a driving simulator as a function of the available field of view. Participants encountered a series of virtual hazards during their drive while viewing the world under narrow or wide field of view conditions. The results showed that all drivers were more likely to avoid the hazards when presented with a wide view, even though the hazards only occurred in an area of the screen that was visible in both the wide and narrow view conditions. Experienced drivers also tended to have fewer crashes, and this appeared to be related to a greater speed reduction 10 metres before the hazard. This speed reduction was greatest in the wide field of view condition suggesting that additional information from wider eccentricities was useful in safely navigating the hazardous events. Gaze movement recording revealed that only experienced drivers made overt use of wider eccentricities, and this was typically in advance of any visual cues that might help identify the hazard. This suggests that either early overt attention to wider eccentricities, or continuous covert attention to these extra-foveal regions on approach to the hazard, is responsible for the safer behaviour of experienced drivers when presented with a wide field of view. We speculate about the possible underlying mechanism and discuss possible consequences for HP tests

Information about the Integer Quantum Hall Transition Extracted from the Autocorrelation Function of Spectral Determinants

The Autocorrelation function of spectral determinants (ASD) is used to probe the sensitivity of a two-dimensional disordered electron gas to the system's size L. For weak magnetic fields ASD is shown to depend only trivially on L, which is a strong indication that all states are localized. From nontrivial dependence of ASD on L for infinite L at a Hall conductance of 1/2 e^2/h we deduce the existence of critical wave functions at this point, as long as the disorder strength does not exceed a critical value.Comment: 4 pages, one citation correcte

Limb kinematics, kinetics and muscle dynamics during the sit-to-stand transition in greyhounds

Standing up from a prone position is a critical daily activity for animals: failing to do so effectively may cause an injurious fall or increase predation susceptibility. This sit-to-stand behaviour (StS) is biomechanically interesting because it necessitates transitioning through near-maximal joint motion ranges from a crouched (i.e., poor mechanical advantage) to a more upright posture. Such large joint excursions should require large length changes of muscle-tendon units. Here we integrate experimental and musculoskeletal simulation methods to quantify the joint motions, limb forces, and muscle fibre forces, activations and length changes during StS in an extreme athlete – the greyhound – which has large hindlimb muscles bearing short-fibred distal muscles and long tendons. Study results indicate that hindlimb anti-gravity muscle fibres operate near their ~50% limits of length change during StS; mostly by starting at highly lengthened positions. StS also requires high muscle activations (>50%), in part due to non-sagittal motions. Finally, StS movements require passive non-muscular support in the distal hindlimb where short-fibred muscles are incapable of sustaining StS themselves. Non-locomotor behaviours like StS likely impose important trade-offs between muscle fibre force capacity and length changes, as well as active and passive mechanisms of support, that have been neglected in locomotor biomechanics studies

Reducing the risk of cognitive decline and dementia: WHO recommendations

With population ageing worldwide, dementia poses one of the greatest global challenges for health and social care in the 21st century. In 2019, around 55 million people were affected by dementia, with the majority living in low- and middle-income countries. Dementia leads to increased costs for governments, communities, families and individuals. Dementia is overwhelming for the family and caregivers of the person with dementia, who are the cornerstone of care and support systems throughout the world. To assist countries in addressing the global burden of dementia, the World Health Organisation (WHO) developed the Global Action Plan on the Public Health Response to Dementia 2017–2025. It proposes actions to be taken by governments, civil society, and other global and regional partners across seven action areas, one of which is dementia risk reduction. This paper is based on WHO Guidelines on risk reduction of cognitive decline and dementia and presents recommendations on evidence-based, multisectoral interventions for reducing dementia risks, considerations for their implementation and policy actions. These global evidence-informed recommendations were developed by WHO, following a rigorous guideline development methodology and involved a panel of academicians and clinicians with multidisciplinary expertise and representing geographical diversity. The recommendations are considered under three broad headings: lifestyle and behaviour interventions, interventions for physical health conditions and specific interventions. By supporting health and social care professionals, particularly by improving their capacity to provide gender and culturally appropriate interventions to the general population, the risk of developing dementia can be potentially reduced, or its progression delayed

A Fast and Reliable Solution to PnP, Using Polynomial Homogeneity and a Theorem of Hilbert

One of the most-extensively studied problems in three-dimensional Computer Vision is “Perspective-n-Point” (PnP), which concerns estimating the pose of a calibrated camera, given a set of 3D points in the world and their corresponding 2D projections in an image captured by the camera. One solution method that ranks as very accurate and robust proceeds by reducing PnP to the minimization of a fourth-degree polynomial over the three-dimensional sphere S3. Despite a great deal of effort, there is no known fast method to obtain this goal. A very common approach is solving a convex relaxation of the problem, using “Sum Of Squares” (SOS) techniques. We offer two contributions in this paper: a faster (by a factor of roughly 10) solution with respect to the state-of-the-art, which relies on the polynomial’s homogeneity; and a fast, guaranteed, easily parallelizable approximation, which makes use of a famous result of Hilbert

Motorcyclists’ and car drivers’ responses to hazards

This study assessed the degree to which hazardous vignettes are perceived as dangerous and realistic by car drivers and motorcycle riders (Exp. 1) and whether riders could be distinguished from drivers on their performance in a commercial motorcycle simulator during safe and hazardous riding situations using the same hazards (Exp. 2). In Experiment 1, car drivers and motorcyclists received a questionnaire which consisted of short descriptions of the scenarios used in the simulator. Half of the car drivers and half of the motorcyclists were told to imagine they were driving a car through the scenario. The other halves were told to imagine they were riding a motorcycle. Respondents with the mindset of a motorcyclist rated the scenarios as more realistic than respondents with a car driver’s mindset. Real-life riders however reported the scenarios as more dangerous than real-life drivers, suggesting that their specific motorcycle experience influenced their criterion for danger. In Experiment 2, naïve participants navigated a simulated route with the same hazards. Performance was coded on objective (e.g., crashes) and subjective (e.g., riding safety and skill) criteria. Experiential differences on some of the measures (and the absence of such differences on other measures) suggest that the simulator is useful for distinguishing riders from drivers during safe periods of riding but not necessarily during hazardous periods of riding. The implications of why hazard vignettes discriminate but the same simulated hazards do not are discussed, with emphasis on the crucial elements required to design a successful simulated hazard

Riding a Motorcycle Simulator: How Do Visual and Non-Visual Cues Contribute to the Illusion of Leaning in a Bend

Since all motion bases of simulator involve intrinsic physical limits, the lack of coupling between visual and inertial cues may be responsible for visuo-vestibular conflict, lowering presence in the virtual environment and increasing simulator sickness. In order to proportion the movements of the motion base and of the visual scenery, the present study aimed at characterizing the coupling between visual and inertial cues that generates a believable and realistic illusion of roll movement in a motorcycle simulator. In the experiment, participants (n=29) actively tuned the visual and physical tilt to achieve the best sensation of leaning, while the theoretical tilt of a real motorcycle (in a similar situation), the road curvature as well as the horizontal field of view (ie,, 60deg vs. 180deg) were manipulated. The results revealed different patterns of use of the visual scenery among riders (eg,, in tilting the visual horizon in the same or in the opposite direction of the displayed curve, or in keeping the visual horizon straight). The results are discussed in terms of the differential roles of tilting the visual and physical dimensions in creating a reliable illusion of riding among motorcyclists