94 research outputs found

    A gradient system with a wiggly energy and relaxed EDP-convergence

    Get PDF
    If gradient systems depend on a microstructure, we want to derive a macroscopic gradient structure describing the effective behavior of the microscopic effects. We introduce a notion of evolutionary Gamma-convergence that relates the microscopic energy and the microscopic dissipation potential with their macroscopic limits via Gamma-convergence. This new notion generalizes the concept of EDP-convergence, which was introduced in arXiv:1507.06322, and is called "relaxed EDP-convergence". Both notions are based on De Giorgi's energy-dissipation principle, however the special structure of the dissipation functional in terms of the primal and dual dissipation potential is, in general, not preserved under Gamma-convergence. By investigating the kinetic relation directly and using general forcings we still derive a unique macroscopic dissipation potential. The wiggly-energy model of James et al serves as a prototypical example where this nontrivial limit passage can be fully analyzed.Comment: 43 pages, 8 figure

    Protest camps

    Get PDF
    Protest camps are global phenomena, occurring across a wide range of social movements and encompassing a diversity of demands for social change. They are spaces where people come together to imagine alternative worlds and articulate contentious politics, often in confrontation with the state. By taking a closer look at protest camps this book contributes two original insights. Firstly it provides a detailed investigation into the empirical history of protest camps from a global perspective, a story that has never been told before. Protest Camps will discuss a variety of examples of camps, taking the reader across different cultural, political and geographical landscapes of protest. Secondly the book will contribute to the understanding of the role of protest camps in contentious politics. This book argues that protest camps are unique spaces in which activists form collective political identities and enact experimental and experiential forms of democratic politics

    A gradient system with a wiggly energy and relaxed EDP-convergence

    Get PDF
    If gradient systems depend on a microstructure, we want to derive a macroscopic gradient structure describing the effective behavior of the microscopic system. We introduce a notion of evolutionary Gamma-convergence that relates the microscopic energy and the microscopic dissipation potential with their macroscopic limits via Gamma-convergence. We call this notion relaxed EDP-convergence since the special structure of the dissipation functional may not be preserved under Gamma-convergence. However, by investigating the kinetic relation we derive the macroscopic dissipation potential

    Assessment of Non-Invasive Blood Pressure Prediction from PPG and rPPG Signals Using Deep Learning

    Get PDF
    Exploiting photoplethysmography signals (PPG) for non-invasive blood pressure (BP) measurement is interesting for various reasons. First, PPG can easily be measured using fingerclip sensors. Second, camera based approaches allow to derive remote PPG (rPPG) signals similar to PPG and therefore provide the opportunity for non-invasive measurements of BP. Various methods relying on machine learning techniques have recently been published. Performances are often reported as the mean average error (MAE) on the data which is problematic. This work aims to analyze the PPG- and rPPG based BP prediction error with respect to the underlying data distribution. First, we train established neural network (NN) architectures and derive an appropriate parameterization of input segments drawn from continuous PPG signals. Second, we use this parameterization to train NNs with a larger PPG dataset and carry out a systematic evaluation of the predicted blood pressure. The analysis revealed a strong systematic increase of the prediction error towards less frequent BP values across NN architectures. Moreover, we tested different train/test set split configurations which underpin the importance of a careful subject-aware dataset assignment to prevent overly optimistic results. Third, we use transfer learning to train the NNs for rPPG based BP prediction. The resulting performances are similar to the PPG-only case. Finally, we apply different personalization techniques and retrain our NNs with subject-specific data for both the PPG-only and rPPG case. Whilst the particular technique is less important, personalization reduces the prediction errors significantly

    Large characteristic lengths in 3D chiral elastic metamaterials

    Get PDF
    Three-dimensional (3D) chiral mechanical metamaterials enable behaviors not accessible in ordinary materials. In particular, a coupling between displacements and rotations can occur, which is symmetry-forbidden without chirality. In this work, we solve three open challenges of chiral metamaterials. First, we provide a simple analytical model, which we use to rationalize the design of the chiral characteristic length. Second, using rapid multi-photon multi-focus 3D laser microprinting, we manufacture samples with more than 105 micrometer-sized 3D chiral unit cells. This number surpasses previous work by more than two orders of magnitude. Third, using analytical and numerical modeling, we realize chiral characteristic lengths of the order of ten unit cells, changing the sample-size dependence qualitatively and quantitatively. In the small-sample limit, the twist per axial strain is initially proportional to the sample side length, reaching a maximum at the characteristic length. In the thermodynamic limit, the twist per axial strain is proportional to the square of the characteristic length. We show that chiral micropolar continuum elasticity can reproduce this behavior

    Comparative study on optical performance and visual outcomes between two diffractive multifocal lenses: AMO TecnisÂź ZMB00 and AcrySofÂź IQ ReSTORÂź Multifocal IOL SN6AD1

    Full text link
    ABSTRACT Purpose: To compare the optical performance and visual outcomes between two diffractive multifocal lenses: AMO TecnisÂź ZMB00 and AcrySofÂź ReSTORÂź SN6AD1. Methods: This prospective, non-randomized comparative study included the assessment of 74 eyes in 37 patients referred for cataract surgery and candidates for multifocal intraocular lens implants. Exclusion criteria included existence of any other eye disease, previous eye surgery, high axial myopia, preoperative corneal astigmatism of >1.00 cylindrical diopter (D), and intraoperative or postoperative complications. Ophthalmological evaluation included the measurement of uncorrected distance visual acuity (UDVA), corrected distance visual acuity (CDVA), distance-corrected near visual acuity (DCNVA), and distance-corrected intermediate visual acuity (DCIVA), with analysis of contrast sensitivity (CS), wavefront, and visual defocus curve. Results: Postoperative UDVA was 0.09 and 0.08 logMAR in the SN6AD1 and ZMB00 groups, respectively (p=0.868); postoperative CDVA was 0.04 and 0.02 logMAR in the SN6AD1 and ZMB00 groups, respectively (p=0.68); DCIVA was 0.17 and 0.54 logMAR in the SN6AD1 and ZMB00 groups, respectively (p=0.000); and DCNVA was 0.04 and 0.09 logMAR in the SN6AD1 and ZMB00 groups, respectively (p=0.001). In both cases, there was an improvement in the spherical equivalent and UDVA (p<0.05). Under photopic conditions, the SN6AD1 group had better CS at low frequencies without glare (p=0.04); however, the ZMB00 group achieved better sensitivity at high frequencies with glare (p=0.003). The SN6AD1 and ZMB00 lenses exhibited similar behavior for intermediate vision, according to the defocus curve; however, the ZMB00 group showed a shorter reading distance than the SN6AD1 group. There were no significant differences regarding aberrometry between the two groups. Conclusion: Both lenses promoted better quality of vision for both long and short distances and exhibited a similar behavior for intermediate vision. The SN6AD1 and ZMB00 groups showed better results for CS under photopic conditions at low and high spatial frequencies, respectively

    Production of in vivo biotinylated scFv specific to almond (Prunus dulcis) proteins by recombinant Pichia pastoris

    Get PDF
    The methylotropic yeast Pichia pastoris has demonstrated its suitability for large-scale production of recombinant proteins. As an eukaryotic organism P. pastoris presents a series of advantages at expression and processing of heterologous proteins when compared with Escherichia coli. In this work, P. pastoris has been used to express a scFv from a human synthetic library previously shown to bind almond proteins. In order to facilitate purification and post processing manipulations, the scFv was engineered with a C-terminal tag and biotinylated in vivo. After purification, biotinylated scFv were bound to avidin conjugated with HRP producing a multimeric scFv. The multimeric scFv showed to maintain their ability to recognize almond protein when assayed in ELISA, reaching a LOD of 470 mg kg−1. This study describes an easy method to produce large quantities of in vivo biotinylated scFv in P. pastoris. By substituting the enzyme or fluorochromes linked to avidin, it will be possible to generate a diverse number of multimeric scFv as probes to suit different analytical platforms in the detection of almond in food products

    Eddy-resolving simulation of plankton ecosystem dynamics in the California Current System

    Get PDF
    Author Posting. © Elsevier B.V., 2006. This is the author's version of the work. It is posted here by permission of Elsevier B.V. for personal use, not for redistribution. The definitive version was published in Deep Sea Research Part I: Oceanographic Research Papers 53 (2006): 1483-1516, doi:10.1016/j.dsr.2006.06.005.We study the dynamics of the planktonic ecosystem in the coastal upwelling zone within the California Current System using a three-dimensional, eddy-resolving circulation model coupled to an ecosystem/biogeochemistry model. The physical model is based on the Regional Oceanic Modeling System (ROMS), configured at a resolution of 15 km for a domain covering the entire U.S. West Coast, with an embedded child grid covering the central California upwelling region at a resolution of 5 km. The model is forced with monthly mean boundary conditions at the open lateral boundaries as well as at the surface. The ecological/biogeochemical model is nitrogen based, includes single classes for phytoplankton and zooplankton, and considers two detrital pools with different sinking speeds. The model also explicitly simulates a variable chlorophyll-to-carbon ratio. Comparisons of model results with either remote sensing observations (AVHRR, SeaWiFS) or in situ measurements from the CalCOFI program indicate that our model is capable of replicating many of the large-scale, time averaged features of the coastal upwelling system. An exception is the underestimation of the chlorophyll levels in the northern part of the domain, perhaps because of the lack of short-term variations in the forcing from the atmosphere. Another shortcoming is that the modeled thermocline is too diffuse, and that the upward slope of the isolines toward the coast is too small. Detailed time-series comparisons with observations from Monterey Bay reveal similar agreements and discrepancies. We attribute the good agreement between the modeled and observed ecological properties in large part to the accuracy of the physical fields. In turn, many of the discrepancies can be traced back to our use of monthly mean forcing. Analysis of the ecosystem structure and dynamics reveal that the magnitude and pattern of phytoplankton biomass in the nearshore region are determined largely by the balance of growth and zooplankton grazing, while in the offshore region, growth is balanced by mortality. The latter appears to be inconsistent with in situ observations and is a result of our consideration of only one zooplankton size class (mesozooplankton), neglecting the importance of microzooplankton grazing in the offshore region. A comparison of the allocation of nitrogen into the different pools of the ecosystem in the 3-D results with those obtained from a box model configuration of the same ecosystem model reveals that only a few components of the ecosystem reach a local steady-state, i.e. where biological sources and sinks balance each other. The balances for the majority of the components are achieved by local biological source and sink terms balancing the net physical divergence, confirming the importance of the 3-D nature of circulation and mixing in a coastal upwelling system.Most of this work has been made possible by two grants from NASA. Additional support is acknowledged from NSF’s ITR program
    • 

    corecore