1,784 research outputs found

    Older people’s emotional connections with their physical urban environment

    Get PDF
    ncreasing urbanization of human society is a universal trend and one that is likely to affect global levels of health and well-being. Rapid expansion of urban living opens new opportunities for people, but also creates significant challenges. We do not always understand how people interact with and connect to their environment, how they experience it and what meaning they attach to certain aspects of it. However, this knowledge can be essential for better understanding of the impact these aspects of the environment can have on their mental health and well-being. In this photo essay, we explore older people’s perceptions of their urban living environment in a highly densely populated urban area; the city of Amsterdam. Participants took photos of salient aspects of their living environment that as they believed influenced their mental health and well-being. Participants searched their living environment for tranquility, peace, beauty, memories and meaning. Listening to the experiences and stories of older adults makes us more aware of their emotional world in this time of global urbanization

    Designing image segmentation studies: Statistical power, sample size and reference standard quality.

    Get PDF
    Segmentation algorithms are typically evaluated by comparison to an accepted reference standard. The cost of generating accurate reference standards for medical image segmentation can be substantial. Since the study cost and the likelihood of detecting a clinically meaningful difference in accuracy both depend on the size and on the quality of the study reference standard, balancing these trade-offs supports the efficient use of research resources. In this work, we derive a statistical power calculation that enables researchers to estimate the appropriate sample size to detect clinically meaningful differences in segmentation accuracy (i.e. the proportion of voxels matching the reference standard) between two algorithms. Furthermore, we derive a formula to relate reference standard errors to their effect on the sample sizes of studies using lower-quality (but potentially more affordable and practically available) reference standards. The accuracy of the derived sample size formula was estimated through Monte Carlo simulation, demonstrating, with 95% confidence, a predicted statistical power within 4% of simulated values across a range of model parameters. This corresponds to sample size errors of less than 4 subjects and errors in the detectable accuracy difference less than 0.6%. The applicability of the formula to real-world data was assessed using bootstrap resampling simulations for pairs of algorithms from the PROMISE12 prostate MR segmentation challenge data set. The model predicted the simulated power for the majority of algorithm pairs within 4% for simulated experiments using a high-quality reference standard and within 6% for simulated experiments using a low-quality reference standard. A case study, also based on the PROMISE12 data, illustrates using the formulae to evaluate whether to use a lower-quality reference standard in a prostate segmentation study

    Nanoscale superconducting gap variations, strong coupling signatures and lack of phase separation in optimally doped BaFe1.86Co0.14As2

    Full text link
    We present tunneling data from optimally-doped, superconducting BaFe1.86Co0.14As2 and its parent compound, BaFe2As2. In the superconductor, clear coherence-like peaks are seen across the whole field of view, and their analysis reveals nanoscale variations in the superconducting gap value, Delta. The average magnitude of 2Delta is ~7.4 kBTC, which exceeds the BCS weak coupling value for either s- or d-wave superconductivity. The characteristic length scales of the deviations from the average gap value, and of an anti-correlation discovered between the gap magnitude and the zero bias conductance, match well with the average separation between the Co dopant ions in the superconducting FeAs planes. The tunneling spectra themselves possess a peak-dip-hump lineshape, suggestive of a coupling of the superconducting electronic system to a well-defined bosonic mode of energy 4.7 kBTC, such as the spin resonance observed recently in inelastic neutron scattering.Comment: 4 figures, corrected typos, reduced size of image

    Virtual-pion and two-photon production in pp scattering

    Full text link
    Two-photon production in pp scattering is proposed as a means of studying virtual-pion emission. Such a process is complementary to real-pion emission in pp scattering. The virtual-pion signal is embedded in a background of double-photon bremsstrahlung. We have developed a model to describe this background process and show that in certain parts of phase space the virtual-pion signal gives significant contribution. In addition, through interference with the two-photon bremsstrahlung background, one can determine the relative phase of the virtual-pion process

    Higher education reform and the landscape diversity of higher education institutions in the Kyrgyz Republic, 1991–2015

    Get PDF
    Following its independence from the Soviet Union in 1991, Kyrgyzstan experienced processes of change across all areas of social, political and economic life. Higher education reform has been central to this agenda, and between 1991 and today the Soviet-era system of state-funded and Communist Party controlled higher education institutions (HEIs) in Kyrgyzstan has been transformed into an expansive, diverse, unequal, semi-privatized and marketized higher education (HE) landscape. Mindful of arguments that the marketization of higher education does not necessarily generate institutional diversification, that government regulation does not necessarily lead to homogenization among institutions, and that universities’ own institutional strategies and responses to environmental changes shape processes of structural reform in complex ways, this paper assesses the specific character of these changes to the higher education landscape in post-Soviet Kyrgyzstan. After briefly describing the structure and financing of higher education in the Kirgiz Soviet Socialist Republic from 1917–1991, we consider some key factors which have shaped patterns of the differentiation and diversification of HE in the post-Soviet period. These include the historical legacies of Soviet HE infrastructures, new legal and political frameworks for HE governance and finance, changes to regulations for the licensing of institutions and academic credentials, the introduction of new multinational policy agendas for higher education in the Central Asian region, changes in the relationship between higher education and labor, the introduction of a national university admissions examination, and the adoption of certain principles of the European Bologna Process. The picture of HE reform that emerges from this analysis is one in which concurrent processes of diversification and homogenization are not driven wholly by either state regulation or forces of market competition, but mediated by universities’ strategic negotiations of these forces in the context of historical institutional formations in Kyrgyzstan

    Wall roughness induces asymptotic ultimate turbulence

    Get PDF
    Turbulence is omnipresent in Nature and technology, governing the transport of heat, mass, and momentum on multiple scales. For real-world applications of wall-bounded turbulence, the underlying surfaces are virtually always rough; yet characterizing and understanding the effects of wall roughness for turbulence remains a challenge, especially for rotating and thermally driven turbulence. By combining extensive experiments and numerical simulations, here, taking as example the paradigmatic Taylor-Couette system (the closed flow between two independently rotating coaxial cylinders), we show how wall roughness greatly enhances the overall transport properties and the corresponding scaling exponents. If only one of the walls is rough, we reveal that the bulk velocity is slaved to the rough side, due to the much stronger coupling to that wall by the detaching flow structures. If both walls are rough, the viscosity dependence is thoroughly eliminated in the boundary layers and we thus achieve asymptotic ultimate turbulence, i.e. the upper limit of transport, whose existence had been predicted by Robert Kraichnan in 1962 (Phys. Fluids {\bf 5}, 1374 (1962)) and in which the scalings laws can be extrapolated to arbitrarily large Reynolds numbers

    (Meta-)stable reconstructions of the diamond(111) surface: interplay between diamond- and graphite-like bonding

    Get PDF
    Off-lattice Grand Canonical Monte Carlo simulations of the clean diamond (111) surface, based on the effective many-body Brenner potential, yield the (2×1)(2\times1) Pandey reconstruction in agreement with \emph{ab-initio} calculations and predict the existence of new meta-stable states, very near in energy, with all surface atoms in three-fold graphite-like bonding. We believe that the long-standing debate on the structural and electronic properties of this surface could be solved by considering this type of carbon-specific configurations.Comment: 4 pages + 4 figures, Phys. Rev. B Rapid Comm., in press (15Apr00). For many additional details (animations, xyz files) see electronic supplement to this paper at http://www.sci.kun.nl/tvs/carbon/meta.htm

    Thermal bremsstrahlung probing the thermodynamical state of multifragmenting systems

    Full text link
    Inclusive and exclusive hard-photon (Eγ>_\gamma > 30 MeV) production in five different heavy-ion reactions (36^{36}Ar+197^{197}Au, 107^{107}Ag, 58^{58}Ni, 12^{12}C at 60{\it A} MeV and 129^{129}Xe+120^{120}Sn at 50{\it A} MeV) has been studied coupling the TAPS photon spectrometer with several charged-particle multidetectors covering more than 80% of 4π\pi. The measured spectra, slope parameters and source velocities as well as their target-dependence, confirm the existence of thermal bremsstrahlung emission from secondary nucleon-nucleon collisions that accounts for roughly 20% of the total hard-photon yield. The thermal slopes are a direct measure of the temperature of the excited nuclear systems produced during the reaction.Comment: 4 pages, 3 figures, Proceedings CRIS 2000, 3rd Catania Relativistic Ion Studies, "Phase Transitions in Strong Interactions: Status and Perspectives", Acicastello, Italy, May 22-26, 2000 (to be published in Nuc. Phys. A

    Pseudogap-less high Tc_{c} superconductivity in BaCox_{x}Fe2x_{2-x}As2_{2}

    Get PDF
    The pseudogap state is one of the peculiarities of the cuprate high temperature superconductors. Here we investigate its presence in BaCox_{x}Fe2x_{2-x}As2_{2}, a member of the pnictide family, with temperature dependent scanning tunneling spectroscopy. We observe that for under, optimally and overdoped systems the gap in the tunneling spectra always closes at the bulk Tc_{c}, ruling out the presence of a pseudogap state. For the underdoped case we observe superconducting gaps over large fields of view, setting a lower limit of tens of nanometers on the length scale of possible phase separated regions.Comment: 5 pages, 3 figure

    Sensitivity of the Atlantic meridional overturning circulation to South Atlantic freshwater anomalies

    No full text
    The sensitivity of the Atlantic Meridional Overturning Circulation (AMOC) to changes in basin integrated net evaporation is highly dependent on the zonal salinity contrast at the southern border of the Atlantic. Biases in the freshwater budget strongly affect the stability of the AMOC in numerical models. The impact of these biases is investigated, by adding local anomaly patterns in the South Atlantic to the freshwater fluxes at the surface. These anomalies impact the freshwater and salt transport by the different components of the ocean circulation, in particular the basin-scale salt-advection feedback, completely changing the response of the AMOC to arbitrary perturbations. It is found that an appropriate dipole anomaly pattern at the southern border of the Atlantic Ocean can collapse the AMOC entirely even without a further hosing. The results suggest a new view on the stability of the AMOC, controlled by processes in the South Atlantic. <br/
    corecore