33 research outputs found

    Worst-Case Morphs Using Wasserstein ALI and Improved MIPGAN

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    A morph is a combination of two separate facial images and contains the identity information of two different people. When used in an identity document, both people can be authenticated by a biometric face recognition (FR) system. Morphs can be generated using either a landmark-based approach or approaches based on deep learning, such as generative adversarial networks (GANs). In a recent paper, we introduced a worst-case upper bound on how challenging morphing attacks can be for an FR system. The closer morphs are to this upper bound, the bigger the challenge they pose to FR. We introduced an approach with which it was possible to generate morphs that approximate this upper bound for a known FR system (white box) but not for unknown (black box) FR systems. In this paper, we introduce a morph generation method that can approximate worst-case morphs even when the FR system is not known. A key contribution is that we include the goal of generating difficult morphs during training. Our method is based on adversarially learned inference (ALI) and uses concepts from Wasserstein GANs trained with gradient penalty, which were introduced to stabilise the training of GANs. We include these concepts to achieve a similar improvement in training stability and call the resulting method Wasserstein ALI (WALI). We finetune WALI using loss functions designed specifically to improve the ability to manipulate identity information in facial images and show how it can generate morphs that are more challenging for FR systems than landmark- or GAN-based morphs. We also show how our findings can be used to improve MIPGAN, an existing StyleGAN-based morph generator

    Work-related upper extremity disorders: one-year follow-up in an occupational diseases registry

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    To study the course and consequences of work-related upper extremity disorders in the registry of the Netherlands Centre for Occupational Diseases (NCvB). A follow-up study was performed in a sample of consecutive cases of work-related upper extremity disorders notified to the NCvB. Perceived severity was measured with VAS (0-100), quality of life with VAS (0-100) and SF-36, functional impairment with DASH and sickness absence with a questionnaire. Measurements took place directly after notification (T0) and after 3, 6 and 12 months (T1-T3). A linear mixed model was used to compare scores over time. Average age of the 48 consecutive patients (89% response) was 42 years; 48% were men. Perceived severity, functional impairment and sickness absence decreased statistically significant during the follow-up period, and quality of life scores improved. Patients older than 45 years scored worse on perceived severity of the disease, functional impairment and quality of life than did younger patients. The role of registries of occupational diseases for preventive policy can be extended by creating longitudinal data in sample projects. In the sample from our registry, work-related upper extremity disorders had a favourable cours

    Information and feedback to improve occupational physicians’ reporting of occupational diseases: a randomised controlled trial

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    To assess the effectiveness of supplying occupational physicians (OPs) with targeted and stage-matched information or with feedback on reporting occupational diseases to the national registry in the Netherlands. In a randomized controlled design, 1076 OPs were divided into three groups based on previous reporting behaviour: precontemplators not considering reporting, contemplators considering reporting and actioners reporting occupational diseases. Precontemplators and contemplators were randomly assigned to receive stage-matched, stage-mismatched or general information. Actioners were randomly assigned to receive personalized or standardized feedback upon notification. Outcome measures were the number of OPs reporting and the number of reported occupational diseases in a 180-day period before and after the intervention. Precontemplators were significantly more male and self-employed compared to contemplators and actioners. There was no significant effect of stage-matched information versus stage-mismatched or general information on the percentage of reporting OPs and on the mean number of notifications in each group. Receiving any information affected reporting more in contemplators than in precontemplators. The mean number of notifications in actioners increased more after personalized feedback than after standardized feedback, but the difference was not significant. This study supports the concept that contemplators are more susceptible to receiving information but could not confirm an effect of stage-matching this information on reporting occupational diseases to the national registr

    Intervention mapping for the development of a strategy to implement the insurance medicine guidelines for depression

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    <p>Abstract</p> <p>Background</p> <p>This article describes the development of a strategy to implement the insurance medicine guidelines for depression. Use of the guidelines is intended to result in more transparent and uniform assessment of claimants with depressive symptoms.</p> <p>Methods</p> <p>The implementation strategy was developed using the Intervention Mapping (IM) method for alignment with insurance-medical practice. The ASE behavioural explanation model (Attitude, Social Influence and Self-Efficacy) was used as theoretical basis for the development work. A literature study of implementation strategies and interviews with insurance physicians were performed to develop instruments for use with the guideline. These instruments were designed to match the needs and the working circumstances of insurance physicians. Performance indicators to measure the quality of the assessment and the adherence to the guidelines were defined with input from insurance physicians.</p> <p>Results</p> <p>This study resulted in the development of a training course to teach insurance physicians how to apply the guidelines for depression, using the aforementioned instruments. The efficacy of this training course will be evaluated in a Randomized Controlled Trial.</p> <p>Conclusions</p> <p>The use of IM made it possible to develop guideline support instruments tailored to insurance medical practice.</p

    Review on the validity of self-report to assess work-related diseases

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    Self-report is an efficient and accepted means of assessing population characteristics, risk factors, and diseases. Little is known on the validity of self-reported work-related illness as an indicator of the presence of a work-related disease. This study reviews the evidence on (1) the validity of workers' self-reported illness and (2) on the validity of workers' self-assessed work relatedness of an illness. A systematic literature search was conducted in four databases (Medline, Embase, PsycINFO and OSH-Update). Two reviewers independently performed the article selection and data extraction. The methodological quality of the studies was evaluated, levels of agreement and predictive values were rated against predefined criteria, and sources of heterogeneity were explored. In 32 studies, workers' self-reports of health conditions were compared with the "reference standard" of expert opinion. We found that agreement was mainly low to moderate. Self-assessed work relatedness of a health condition was examined in only four studies, showing low-to-moderate agreement with expert assessment. The health condition, type of questionnaire, and the case definitions for both self-report and reference standards influence the results of validation studies. Workers' self-reported illness may provide valuable information on the presence of disease, although the generalizability of the findings is limited primarily to musculoskeletal and skin disorders. For case finding in a population at risk, e.g., an active workers' health surveillance program, a sensitive symptom questionnaire with a follow-up by a medical examination may be the best choice. Evidence on the validity of self-assessed work relatedness of a health condition is scarce. Adding well-developed questions to a specific medical diagnosis exploring the relationship between symptoms and work may be a good strateg

    Matching 3-D textures with measured images

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    Modelling and analysis of true 3-D textures

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    Hand assessment with the E-Cone in rheumatoid arthritis and hand osteoarthritis

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    Background:\ud Rheumatoid arthritis (RA) is a systemic inflammatory, progressive disease resulting in deformities of the hand. Besides synovitis, tenosynovitis of the extrinsic flexor tendons is one of the initial features of RA, leading to friction and consequently to an imbalanced coordination of the hand muscles. This phenomenon is also seen in patients with hand osteoarthritis (HOA).\ud For the treatment of RA and HOA, focused on optimal hand coordination, feedback regarding the coordination of the intrinsic and extrinsic muscles is essential. We have developed a new device to provide this feedback, by means of pressure sensors attached to a cone that register and visualize the distribution of hand pressure on a screen: the E-cone (figure 1). In clinical practice, the E-cone has been successfully used as a treatment device; patients can easily interpret the image on the screen, and use this as cue to improve their handgrip. In order to implement the E-cone as a diagnostic device, inter- and intra-observer reliability has to be determined.\ud \ud Objectives:\ud To assess the reliability of the E-cone in RA or HOA patients and healthy subjects, while assessing the handgrip pattern and pressure distribution.\ud \ud Methods:\ud This study included patients with RA or HOA, treated in the hand rehabilitation team, and healthy subjects without impairments. The subjects raised the E-cone with each hand successively. This assessment was filmed with a webcam. The handgrip pattern and the pressure distribution were assessed twice, using a 5-point Numeric Rating Scale by two independent assessors separately, using the film for the assessment of the handgrip pattern. The inter- and intra-rater reliability were calculated via intra-class correlation (ICC).\ud \ud Results: \ud Fifty participants (9 RA, 17 HOA and 24 healthy subjects) were assessed; mean age 49.8 years (59.8, 64.4 and 35.7), 88% females. The inter- and intra-rater reliability of the handgrip pattern were in moderate agreement with intra-class correlations of 0.48 and 0.49 respectively. The inter- and intra-rater reliability of the pressure distribution were in fair agreement, both with an intra-class correlation of 0.38.\ud \ud Conclusions:\ud Although the E-cone can easily and successfully be used as a treatment device in restoring handgrip coordination and facilitating tendon gliding in stenosing tenosynovitis, the device can not yet be used as a diagnostic tool
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