294 research outputs found

    Flow distributed oscillation, flow velocity modulation and resonance

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    We examine the effects of a periodically varying flow velocity on the standing and travelling wave patterns formed by the flow-distributed oscillation (FDO) mechanism. In the kinematic (or diffusionless) limit, the phase fronts undergo a simple, spatiotemporally periodic longitudinal displacement. On the other hand, when the diffusion is significant, periodic modulation of the velocity can disrupt the wave pattern, giving rise in the downstream region to travelling waves whose frequency is a rational multiple of the velocity perturbation frequency. We observe frequency locking at ratios of 1:1, 2:1 and 3:1, depending on the amplitude and frequency of the velocity modulation. This phenomenon can be viewed as a novel, rather subtle type of resonant forcing.Comment: submitted to Phys. Rev.

    Can commitments cause counterpreferential choices?

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    Commitments are crucial for our lives but there is no consensus on how commitments and preferences relate to each other. In this paper, we present three empirical studies that provide evidence that people sometimes choose a less preferred option when they have made a commitment

    Finding Homogeneity in Heterogeneity—A New Approach to Quantifying Landscape Mosaics Developed for the Lao PDR

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    A key challenge for land change science in general and research on swidden agriculture in particular, is linking land cover information to human-environment interactions over larger spatial areas. In Lao PDR, a country facing rapid and multi-level land change processes, this hinders informed policy- and decision-making. Crucial information on land use types and people involved is still lacking. This article proposes an alternative approach for the description of landscape mosaics. Instead of analyzing local land use combinations, we studied land cover mosaics at a meso-level of spatial scale and interpreted these in terms of human-environmental interactions. These landscape mosaics were then overlaid with population census data. Results showed that swidden agricultural landscapes, involving 17% of the population, dominate 29% of the country, while permanent agricultural landscapes involve 74% of the population in 29% of the territory. Forests still form an important component of these landscape mosaic

    Not more than a feeling: An experimental investigation into the folk concept of happiness

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    Affect-based theorists and life satisfaction theorists disagree about the nature of happiness, but agree about this methodological principle: a philosophical theory of happiness should be in line with the folk concept HAPPINESS. In this article, we present two empirical studies indicating that it is affect-based theories that get the folk concept HAPPINESS right: competent speakers judge a person to be happy if and only if that person is described as feeling pleasure/good most of the time. Our studies also show that the judgement that a person is feeling pleasure/good most of the time reliably brings about the judgement that they are satisfied with their life, even if that person is described as not satisfied. We suggest that this direct causal relation between the concepts POSITIVE AFFECT and LIFE SATISFACTION might explain why many philosophers have been attracted to life satisfaction theories

    The varying rationality of weakness of the will: an empirical investigation and its challenges for a unified theory of rationality

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    Weakness of the will remains a perplexing issue. Though philosophers have made substantial progress in homing in on what counts as a weak will, there is little agreement on whether weakness of the will is irrational, and if so, why. In this paper, we take an empirical approach towards the rationality of weakness of the will. After introducing the philosophical debate, we present the results of an empirical study that reveals that people take a “dual sensitivity”, as we shall put it, towards assessing the rationality of weak-willed behavior. Put succinctly, intending X against your value judgements is assessed irrational; yet, in the same situation, intending X is assessed significantly less irrational if you judge X as something you ought to do. After discussing this result, we turn to the question of whether there is a plausible theory of rationality than can account for the dual sensitivity of the rationality assessments. We show that a success-based account can make sense of the dual sensitivity our empirical results reveal

    Reduced incidence of atrial fibrillation after cardiac surgery by continuous wireless monitoring of oxygen saturation on the normal ward and resultant oxygen therapy for hypoxia

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    Objective: Monitoring of cardiac surgical patients after transfer from the intensive care unit to the normal ward is incomplete. Undetected hypoxia, however, is known to be a risk factor for occurrence of atrial fibrillation. We have utilized Auricall® for continuous wireless monitoring of oxygen saturation and heart rate until discharge. The object of the study was to analyze if oxygen therapy as a result of Auricall® alerts of hypoxia can decrease the incidence of postoperative atrial fibrillation. Methods: Auricall® is a wireless portable pulse oximeter. An alert is generated depending on preset threshold values (heart rate, oxygen saturation). Over a period of 6 months, 119 patients were monitored with the Auricall® following coronary artery bypass graft and/or valve surgery. Oxygen therapy was started subsequent to an oxygen saturation below 90%. These patients were compared with a cohort of 238 patients from the time period before availability of Auricall®. The patient characteristics were comparable in both groups. In a retrospective study, the incidence of atrial fibrillation was measured in both groups. Results: The postoperative AF was observed in 22/119 patients (18%) in group I and in 66/238 patients (28%) in group II. This difference between the two groups approached significance (p=0.056). In the subgroup of patients with coronary artery bypass graft with our without simultaneous valve surgery (n=312), Auricall® monitoring resulted in a significantly reduced incidence of atrial fibrillation (14% vs 26%, p=0.016). Conclusions: Continuous monitoring of oxygen saturation on the normal ward and subsequent oxygen therapy for hypoxia can reduce the incidence of atrial fibrillation in a subgroup of patients after cardiac surgery. Prospective randomized trials are warranted to confirm these dat

    Socio-Economic Perspectives on Shifting Cultivation Landscapes in Northern Laos

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    Despite the rapid agricultural transition that has occurred in the past decade, shifting cultivation remains a widespread agricultural practice in the northern uplands of Lao PDR. Little information is available on the basic socio-economic situation and respective possible patterns in shifting cultivation landscapes on a regional level. On the basis of a recent approximation of the extent of shifting cultivation landscapes for two time periods and disaggregated village level census data, this paper characterizes these landscapes in terms of key socioeconomic parameters for the whole of northern Laos. Results showed that over 550,000 people live in shifting cultivation regions. The poverty rate of this population of 46.5% is considerably higher than the national rural rate. Most shifting cultivation landscapes are located in remote locations and a high share of the population comprises ethnic minorities, pointing to multi-dimensional marginality of these areas. We discuss whether economic growth and increased market accessibility are sufficient to lift these landscapes out of povert

    Comparability of Pulmonary Nodule Size Measurements among Different Scanners and Protocols: Should Diameter Be Favorized over Volume?

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    BACKGROUND: To assess the impact of the lung cancer screening protocol recommended by the European Society of Thoracic Imaging (ESTI) on nodule diameter, volume, and density throughout different computed tomography (CT) scanners. METHODS: An anthropomorphic chest phantom containing fourteen different-sized (range 3-12 mm) and CT-attenuated (100 HU, -630 HU and -800 HU, termed as solid, GG1 and GG2) pulmonary nodules was imaged on five CT scanners with institute-specific standard protocols (PS_{S}) and the lung cancer screening protocol recommended by ESTI (ESTI protocol, PE_{E}). Images were reconstructed with filtered back projection (FBP) and iterative reconstruction (REC). Image noise, nodule density and size (diameter/volume) were measured. Absolute percentage errors (APEs) of measurements were calculated. RESULTS: Using PE_{E}, dosage variance between different scanners tended to decrease compared to PS_{S}, and the mean differences were statistically insignificant (p = 0.48). PS_{S} and PE(REC)_{E(REC)} showed significantly less image noise than PE(FBP)_{E(FBP)} (p < 0.001). The smallest size measurement errors were noted with volumetric measurements in PE(REC)_{E(REC)} and highest with diametric measurements in PE(FBP)_{E(FBP)}. Volume performed better than diameter measurements in solid and GG1 nodules (p < 0.001). However, in GG2 nodules, this could not be observed (p = 0.20). Regarding nodule density, REC values were more consistent throughout different scanners and protocols. CONCLUSION: Considering radiation dose, image noise, nodule size, and density measurements, we fully endorse the ESTI screening protocol including the use of REC. For size measurements, volume should be preferred over diameter

    Not more than a feeling: An experimental investigation into the folk concept of happiness

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    Affect-based theorists and life satisfaction theorists disagree about the nature of happiness, but agree about this methodological principle: a philosophical theory of happiness should be in line with the folk concept HAPPINESS. In this article, we present two empirical studies indicating that it is affect-based theories that get the folk concept HAPPINESS right: competent speakers judge a person to be happy if and only if that person is described as feeling pleasure/good most of the time. Our studies also show that the judgement that a person is feeling pleasure/good most of the time reliably brings about the judgement that they are satisfied with their life, even if that person is described as not satisfied. We suggest that this direct causal relation between the concepts POSITIVE AFFECT and LIFE SATISFACTION might explain why many philosophers have been attracted to life satisfaction theories

    Fully automated deep learning powered calcium scoring in patients undergoing myocardial perfusion imaging

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    BACKGROUND To assess the accuracy of fully automated deep learning (DL) based coronary artery calcium scoring (CACS) from non-contrast computed tomography (CT) as acquired for attenuation correction (AC) of cardiac single-photon-emission computed tomography myocardial perfusion imaging (SPECT-MPI). METHODS AND RESULTS Patients were enrolled in this study as part of a larger prospective study (NCT03637231). In this study, 56 Patients who underwent cardiac SPECT-MPI due to suspected coronary artery disease (CAD) were prospectively enrolled. All patients underwent non-contrast CT for AC of SPECT-MPI twice. CACS was manually assessed (serving as standard of reference) on both CT datasets (n = 112) and by a cloud-based DL tool. The agreement in CAC scores and CAC score risk categories was quantified. For the 112 scans included in the analysis, interscore agreement between the CAC scores of the standard of reference and the DL tool was 0.986. The agreement in risk categories was 0.977 with a reclassification rate of 3.6%. Heart rate, image noise, body mass index (BMI), and scan did not significantly impact (p=0.09 - p=0.76) absolute percentage difference in CAC scores. CONCLUSION A DL tool enables a fully automated and accurate estimation of CAC scores in patients undergoing non-contrast CT for AC of SPECT-MPI
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