456 research outputs found

    The spatial evolution of the British automobile industry

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    This paper aims to describe and explain the spatial evolution of the automobile sector in Great Britain from an evolutionary perspective. This analysis is based on a unique database of all entries and exits in this sector during the period 1895-1968, collected by the authors. Cox regressions show that spinoff dynamics, localization economies and time of entry have had a significant effect on the survival rate of automobile firms during the period 1895-1968.evolutionary economics, automobile industry, entry, exit

    Fence-sitters Protect Cooperation in Complex Networks

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    Evolutionary game theory is one of the key paradigms behind many scientific disciplines from science to engineering. In complex networks, because of the difficulty of formulating the replicator dynamics, most of previous studies are confined to a numerical level. In this paper, we introduce a vectorial formulation to derive three classes of individuals' payoff analytically. The three classes are pure cooperators, pure defectors, and fence-sitters. Here, fence-sitters are the individuals who change their strategies at least once in the strategy evolutionary process. As a general approach, our vectorial formalization can be applied to all the two-strategies games. To clarify the function of the fence-sitters, we define a parameter, payoff memory, as the number of rounds that the individuals' payoffs are aggregated. We observe that the payoff memory can control the fence-sitters' effects and the level of cooperation efficiently. Our results indicate that the fence-sitters' role is nontrivial in the complex topologies, which protects cooperation in an indirect way. Our results may provide a better understanding of the composition of cooperators in a circumstance where the temptation to defect is larger.Comment: an article with 6 pages, 3 figure

    Emergence of Cooperation in Non-scale-free Networks

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    Evolutionary game theory is one of the key paradigms behind many scientific disciplines from science to engineering. Previous studies proposed a strategy updating mechanism, which successfully demonstrated that the scale-free network can provide a framework for the emergence of cooperation. Instead, individuals in random graphs and small-world networks do not favor cooperation under this updating rule. However, a recent empirical result shows the heterogeneous networks do not promote cooperation when humans play a Prisoner's Dilemma. In this paper, we propose a strategy updating rule with payoff memory. We observe that the random graphs and small-world networks can provide even better frameworks for cooperation than the scale-free networks in this scenario. Our observations suggest that the degree heterogeneity may be neither a sufficient condition nor a necessary condition for the widespread cooperation in complex networks. Also, the topological structures are not sufficed to determine the level of cooperation in complex networks.Comment: 6 pages, 5 figure

    Timing matters: impact of anticonvulsant drug treatment and spikes on seizure risk in benign epilepsy with centrotemporal spikes

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    OBJECTIVE: Benign epilepsy with centrotemporal spikes (BECTS) is a common, self-limited epilepsy syndrome affecting school-age children. Classic interictal epileptiform discharges (IEDs) confirm diagnosis, and BECTS is presumed to be pharmacoresponsive. As seizure risk decreases in time with this disease, we hypothesize that the impact of IEDs and anticonvulsive drug (ACD) treatment on the risk of subsequent seizure will differ based on disease duration. METHODS: We calculate subsequent seizure risk following diagnosis in a large retrospective cohort of children with BECTS (n = 130), evaluating the impact of IEDs and ACD treatment in the first, second, third, and fourth years of disease. We use a Kaplan-Meier survival analysis and logistic regression models. Patients were censored if they were lost to follow-up or if they changed group status. RESULTS: Two-thirds of children had a subsequent seizure within 2 years of diagnosis. The majority of children had a subsequent seizure within 3 years despite treatment. The presence of IEDs on electroencephalography (EEG) did not impact subsequent seizure risk early in the disease. By the fourth year of disease, all children without IEDs remained seizure free, whereas one-third of children with IEDs at this stage had a subsequent seizure. Conversely, ACD treatment corresponded with lower risk of seizure early in the disease but did not impact seizure risk in later years. SIGNIFICANCE: In this cohort, the majority of children with BECTS had a subsequent seizure despite treatment. In addition, ACD treatment and IEDs predicted seizure risk at specific points of disease duration. Future prospective studies are needed to validate these exploratory findings.Published versio

    Time-Delayed Integration–Spectral Flow Cytometer (TDI-SFC) for Low-Abundance-Cell Immunophenotyping

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    This document is the Accepted Manuscript version of a Published Work that appeared in final form in Analytical Chemistry, copyright © American Chemical Society after peer review and technical editing by the publisher. To access the final edited and published work see http://doi.org/10.1021/acs.analchem.9b00021.We describe a unique flow cytometer (TDI-SFC) for the immunophenotyping of low-abundance cells, particularly when cell counts are sample-limited and operationally difficult for analysis by fluorescence microscopy (>100 cells) or multiparameter flow cytometry (MFC, <10 000 cells). TDI-SFC combines the high spectral resolution of spectral flow cytometry (SFC) with a CCD operated in time-delayed integration (TDI) for improved duty cycle and sensitivity. Cells were focused with a 1D-sheathing microfluidic device, and fluorescence emission generated from a 488 nm laser was collected by epi-illumination and dispersed along one axis of a CCD by a spectrograph. Along the other axis, the CCD’s shift rate was clocked at a rate that closely matched the cells’ velocity through the field of view. This TDI-SFC format allowed the CCD shutter to remain open during signal acquisition, providing a duty cycle ∼100% and assurance that ∼95% cells were interrogated. We used fluorescent beads to optimize synchronization of TDI clocking with the sheathed-cell velocity and to improve sensitivity via the excitation intensity, epi-illumination numerical aperture, and integration time. TDI achieved integrated signals of 106 counts at a signal-to-noise ratio (SNR) of 610 for beads corresponding to a load of 4 × 105 antibodies. We also evaluated multiplexing capabilities by spectral deconvolution and undertook a proof-of-concept application to immunophenotype low-abundance cells; the demonstration consisted of immunophenotyping a model cell line, in this case SUP-B15 cells representing B-cell acute lymphoblastic leukemia (B-ALL). The B-ALL cell line was stained against a leukemic marker (terminal deoxynucleotidyl transferase, TdT), and we successfully used spectral unmixing to discriminate TdT(+) cells from TdT(−) cells even at low cell counts (∼100 cells). The TDI-SFC could potentially be used in any application requiring the immunophenotyping of low-abundance cells, such as in monitoring measurable residual disease in acute leukemias following affinity enrichment of circulating leukemia cells from peripheral blood

    Interpersonal functioning in hoarding : an investigation of the link between hoarding symptoms and social support, social anhedonia, and social rewards

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    Background: One of the key areas of functional impairment in hoarding is interpersonal difficulties, with burgeoning evidence suggesting that these social difficulties are a component of the psychopathology observed in hoarding. The specific nature of these interpersonal difficulties, however, has yet to be fully elucidated. The aim of the current study was to investigate the contribution of social support and motivation to socialise, specifically social anhedonia and rewards from social stimuli, to hoarding symptom severity. Method: A total of 278 participants recruited via the crowd-sourcing website MTurk completed questionnaires assessing hoarding symptoms, social support, social anhedonia, and response to social rewards. Results: Results for social reward processing indicated that hoarding symptoms were associated with finding both negative and positive behaviours towards others more rewarding. Social anhedonia also positively predicted hoarding symptoms. Furthermore, social integration, a component of social support, was inversely associated with hoarding symptoms. These associations remained significant when controlling for depressive symptoms. These results suggest that hoarding may be linked to decreased social support and reduced social motivation, particularly, dysregulated reward processing of social stimuli, and greater social anhedonia. Limitations: Limitations of the current study include utilising an unselected sample, use of self-report measures, and analyses being correlational in nature. Future research utilising longitudinal or experimental research methods in a clinical population may further delineate the clinical conceptualisation of social difficulties in hoarding disorder. Conclusions: Current findings may inform interpersonal conceptualisations for hoarding disorder and suggest additional treatment avenues

    Informing a risk prediction model for binary outcomes with external coefficient information

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    Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/146799/1/rssc12306-sup-0001-SupInfo.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/146799/2/rssc12306_am.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/146799/3/rssc12306.pd

    The stellar halo of isolated central galaxies in the Hyper Suprime-Cam imaging survey

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    We study the faint stellar halo of isolated central galaxies, by stacking galaxy images in the HSC survey and accounting for the residual sky background sampled with random points. The surface brightness profiles in HSC rr-band are measured for a wide range of galaxy stellar masses (9.2<log10M/M<11.49.2<\log_{10}M_\ast/M_\odot<11.4) and out to 120 kpc. Failing to account for the stellar halo below the noise level of individual images will lead to underestimates of the total luminosity by 15%\leq 15\%. Splitting galaxies according to the concentration parameter of their light distributions, we find that the surface brightness profiles of low concentration galaxies drop faster between 20 and 100 kpc than those of high concentration galaxies. Albeit the large galaxy-to-galaxy scatter, we find a strong self-similarity of the stellar halo profiles. They show unified forms once the projected distance is scaled by the halo virial radius. The colour of galaxies is redder in the centre and bluer outside, with high concentration galaxies having redder and more flattened colour profiles. There are indications of a colour minimum, beyond which the colour of the outer stellar halo turns red again. This colour minimum, however, is very sensitive to the completeness in masking satellite galaxies. We also examine the effect of the extended PSF in the measurement of the stellar halo, which is particularly important for low mass or low concentration galaxies. The PSF-corrected surface brightness profile can be measured down to \sim31 mag/arcsec2\mathrm{mag}/\mathrm{arcsec}^2 at 3-σ\sigma significance. PSF also slightly flattens the measured colour profiles.Comment: accepted by MNRAS - Significant changes have been made compared with the first version, including discussions on the extended PSF wings, robustness of our results to source detection and masking thresholds and more detailed investigations on the indications of positive colour gradient

    A supervised texton based approach for automatic segmentation and measurement of the fetal head and femur in 2D ultrasound images

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    This paper presents a supervised texton based approach for the accurate segmentation and measurement of ultrasound fetal head (BPD, OFD, HC) and femur (FL). The method consists of several steps. First, a non-linear diffusion technique is utilized to reduce the speckle noise. Then, based on the assumption that cross sectional intensity profiles of skull and femur can be approximated by Gaussian-like curves, a multi-scale and multi-orientation filter bank is designed to extract texton features specific to ultrasound fetal anatomic structure. The extracted texton cues, together with multi-scale local brightness, are then built into a unified framework for boundary detection of ultrasound fetal head and femur. Finally, for fetal head, a direct least square ellipse fitting method is used to construct a closed head contour, whilst, for fetal femur a closed contour is produced by connecting the detected femur boundaries. The presented method is demonstrated to be promising for clinical applications. Overall the evaluation results of fetal head segmentation and measurement from our method are comparable with the inter-observer difference of experts, with the best average precision of 96.85%, the maximum symmetric contour distance (MSD) of 1.46 mm, average symmetric contour distance (ASD) of 0.53 mm; while for fetal femur, the overall performance of our method is better than the inter-observer difference of experts, with the average precision of 84.37%, MSD of 2.72 mm and ASD of 0.31 mm
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