| 731. |
- Dahlqvist, Camilla, et al.
(författare)
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Comparing two methods to record maximal voluntary contractions and different electrode positions in recordings of forearm extensor muscle activity : refining risk assessments for work-related wrist disorders
- 2018
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Ingår i: Work. - : IOS Press. - 1051-9815. ; 59:2, s. 231-242
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Tidskriftsartikel (refereegranskat)abstract
- Background: Wrist disorders are common in force demanding industrial repetitive work. Visual assessment of force demands have a low reliability, instead surface electromyography (EMG) may be used as part of a risk assessment for work-related wrist disorders. For normalization of EMG recordings, a power grip (hand grip) is often used as maximal voluntary contraction (MVC) of the forearm extensor muscles. However, the test-retest reproducibility is poor and EMG amplitudes exceeding 100% have occasionally been recorded during work. An alternative MVC is resisted wrist extension, which may be more reliable.Objective: To compare hand grip and resisted wrist extension MVCs, in terms of amplitude and reproducibility, and to examine the effect of electrode positioning.Methods: Twelve subjects participated. EMG from right forearm extensors, from four electrode pairs, was recorded during MVCs, on three separate occasions.Results: The group mean EMG amplitudes for resisted wrist extension were 1.2-1.7 times greater than those for hand grip. Resisted wrist extension showed better reproducibility than hand grip.Conclusions: The results indicate that the use of resisted wrist extension is a more accurate measurement of maximal effort of wrist extensor contractions than using hand grip and should increase the precision in EMG recordings from forearm extensor muscles, which in turn will increase the quality of risk assessments that are based on these.
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| 732. |
- Dahlqvist, Camilla, et al.
(författare)
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Self-recordings of upper arm elevation during cleaning - comparison between analyses using a simplified reference posture and a standard reference posture
- 2018
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Ingår i: BMC Musculoskeletal Disorders. - : BMC. - 1471-2474. ; 19
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Tidskriftsartikel (refereegranskat)abstract
- Background To reduce ergonomic risk factors in terms of awkward and constrained postures and high velocities, it is important to perform adequate risk assessments. Technical methods provide objective measures of physical workload. These methods have so far mainly been used by researchers. However, if written instructions how to apply the sensors and how to adopt the reference posture are provided, together with triaxial accelerometers, it may be possible for employees to record their own physical workload. The exposure in terms of e.g. upper arm elevations could then easily be assessed for all workers in a workplace. The main aims of this study were: 1) to compare analyses for self-recording of upper arm elevation during work using a simplified reference posture versus using a standard reference posture, and 2) to compare the two reference postures.MethodsTwenty-eight cleaners attached an accelerometer to their dominant upper arm and adopted a simplified reference according to a written instruction. They were thereafter instructed by a researcher to adopt a standard reference. Upper arm elevations were recorded for 2 or 3 days. Each recording was analysed twice; relative to the simplified reference posture and relative to the standard reference posture. The group means of the differences in recorded upper arm elevations between simplified and standard reference analyses were assessed using Wilcoxon signed ranks test. Furthermore, we calculated the group mean of the differences between the simplified reference posture and the standard reference posture.ResultsFor arm elevation during work (50(th) percentile), the group mean of the differences between the two analyses was 0.2 degrees (range-7 - 10 degrees). The group mean of the differences between the two references was 9 degrees (range 1-21 degrees). The subjects were able to follow the instructions in the protocol and performed self-recording of upper arm elevation and velocity.ConclusionsThe small difference between the two analyses indicates that recordings performed by employees themselves are comparable, on a group level, with those performed by researchers. Self-recordings in combination with action levels would provide employers with a method for risk assessment as a solid basis for prevention of work-related musculoskeletal disorders.
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| 733. |
- Dahlqvist, Camilla, et al.
(författare)
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Validity of a small low-cost triaxial accelerometer with integrated logger for uncomplicated measurements of postures and movements of head, upper back and upper arms
- 2016
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Ingår i: Applied Ergonomics. - : Elsevier. - 0003-6870 .- 1872-9126. ; 55, s. 108-116
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Tidskriftsartikel (refereegranskat)abstract
- Repetitive work and work in constrained postures are risk factors for developing musculoskeletal disorders. Low-cost, user-friendly technical methods to quantify these risks are needed. The aims were to validate inclination angles and velocities of one model of the new generation of accelerometers with integrated data loggers against a previously validated one, and to compare meaurements when using a plain reference posture with that of a standardized one. All mean (n = 12 subjects) angular RMS-differences in 4 work tasks and 4 body parts were <2.5° and all mean median angular velocity differences <5.0 °/s. The mean correlation between the inclination signal-pairs was 0.996. This model of the new generation of triaxial accelerometers proved to be comparable to the validated accelerometer using a data logger. This makes it well-suited, for both researchers and practitioners, to measure postures and movements during work. Further work is needed for validation of the plain reference posture for upper arms.
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| 734. |
- Dahlstedt, Magnus, et al.
(författare)
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Longing to belong : Stories of (non)belonging in multi-ethnic Sweden
- 2017
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Ingår i: Nordic Journal of Migration Research. - : De Gruyter Open. - 1799-649X. ; 7:4, s. 197-204
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Tidskriftsartikel (refereegranskat)abstract
- The aim of this article is to contribute to an understanding of contemporary processes of negotiations concerning belonging and non-belonging to the Swedish social community. Taking on a theoretical approach on belonging inspired by Yuval-Davis and Jacobsen, the article analyses three individual stories of women who have migrated to Sweden. Out of this analysis, focusing on how these women claim their belonging to a Swedish social community at the same time as they in different ways are denied such belonging by others, we may conclude that although each of the stories told is unique and articulates an individual experience, there are striking similarities in how their claims of belonging, with its related implications for belonging, are not acknowledged by others. In a way, these individual stories tell us something about some of the crucial challenges regarding belonging in contemporary multi-ethnic Sweden, as well as Europe.
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| 735. |
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| 736. |
- Dalarsson, Mariana, et al.
(författare)
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Absorption and optimal plasmonic resonances for small ellipsoidal particles in lossy media
- 2017
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Ingår i: Journal of Physics D. - : Institute of Physics (IOP). - 0022-3727 .- 1361-6463. ; 50:34
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Tidskriftsartikel (refereegranskat)abstract
- A new simplified formula is derived for the absorption cross section of small dielectric ellipsoidal particles embedded in lossy media. The new expression leads directly to a closed form solution for the optimal conjugate match with respect to the surrounding medium, i.e. the optimal permittivity of the ellipsoidal particle that maximizes the absorption at any given frequency. This defines the optimal plasmonic resonance for the ellipsoid. The optimal conjugate match represents a metamaterial in the sense that the corresponding optimal permittivity function may have negative real part (inductive properties), and can not in general be implemented as a passive material over a given bandwidth. A necessary and sufficient condition is derived for the feasibility of tuning the Drude model to the optimal conjugate match at a single frequency, and it is found that all the prolate spheroids and some of the (not too flat) oblate spheroids can be tuned into optimal plasmonic resonance at any desired center frequency. Numerical examples are given to illustrate the analysis. Except for the general understanding of plasmonic resonances in lossy media, it is also anticipated that the new results can be useful for feasibility studies with e.g. the radiotherapeutic hyperthermia based methods to treat cancer based on electrophoretic heating in gold nanoparticle suspensions using microwave radiation.
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| 737. |
- D'Alisa, Giacomo, et al.
(författare)
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Rethink Campania's toxic-waste scandal
- 2014
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Ingår i: Nature. - : Springer Science and Business Media LLC. - 0028-0836 .- 1476-4687. ; 509:7501, s. 427-427
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Tidskriftsartikel (refereegranskat)
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| 738. |
- Darabi, H., et al.
(författare)
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Development of a novel hybrid multi-boosting neural network model for spatial prediction of urban flood
- 2021
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Ingår i: Geocarto International. - : Taylor and Francis Ltd.. - 1010-6049 .- 1752-0762.
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Tidskriftsartikel (refereegranskat)abstract
- In this study, a new hybridized machine learning algorithm for urban flood susceptibility mapping, named MultiB-MLPNN, was developed using a multi-boosting technique and MLPNN. The model was tested in Amol City, Iran, a data-scarce city in an ungauged area which is prone to severe flood inundation events and currently lacks flood prevention infrastructure. Performance of the hybridized model was compared with that of a standalone MLPNN model, random forest and boosted regression trees. Area under the curve, efficiency, true skill statistic, Matthews correlation coefficient, misclassification rate, sensitivity and specificity were used to evaluate model performance. In validation, the MultiB-MLPNN model showed the best predictive performance. The hybridized MultiB-MLPNN model is thus useful for generating realistic flood susceptibility maps for data-scarce urban areas. The maps can be used to develop risk-reduction measures to protect urban areas from devastating floods, particularly where available data are insufficient to support physically based hydrological or hydraulic models.
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| 739. |
- De Gracia Triviño, Juan Angel, et al.
(författare)
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Complete Active Space Methods for NISQ Devices: The Importance of Canonical Orbital Optimization for Accuracy and Noise Resilience
- 2023
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Ingår i: Journal of Chemical Theory and Computation. - : American Chemical Society (ACS). - 1549-9618 .- 1549-9626. ; 19:10, s. 2863-2872
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Tidskriftsartikel (refereegranskat)abstract
- To avoid the scaling of the number of qubits with the size of the basis set, one can divide the molecular space into active and inactive regions, which is also known as complete active space methods. However, selecting the active space alone is not enough to accurately describe quantum mechanical effects such as correlation. This study emphasizes the importance of optimizing the active space orbitals to describe correlation and improve the basis-dependent Hartree-Fock energies. We will explore classical and quantum computation methods for orbital optimization and compare the chemically inspired ansatz, UCCSD, with the classical full CI approach for describing the active space in both weakly and strongly correlated molecules. Finally, we will investigate the practical implementation of a quantum CASSCF, where hardware-efficient circuits must be used and noise can interfere with accuracy and convergence. Additionally, we will examine the impact of using canonical and noncanonical active orbitals on the convergence of the quantum CASSCF routine in the presence of noise.
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| 740. |
- de Rezende, Susanna F., et al.
(författare)
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Exponential resolution lower bounds for weak pigeonhole principle and perfect matching formulas over sparse graphs
- 2020
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Ingår i: CCC '20: Proceedings of the 35th Computational Complexity Conference 2020. - : Schloss Dagstuhl–Leibniz-Zentrum für Informatik. - 1868-8969. - 9783959771566 ; 169, s. 28-1
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Konferensbidrag (refereegranskat)abstract
- We show exponential lower bounds on resolution proof length for pigeonhole principle (PHP) formulas and perfect matching formulas over highly unbalanced, sparse expander graphs, thus answering the challenge to establish strong lower bounds in the regime between balanced constant-degree expanders as in [Ben-Sasson and Wigderson'01] and highly unbalanced, dense graphs as in [Raz'04] and [Razborov'03,'04]. We obtain our results by revisiting Razborov's pseudo-width method for PHP formulas over dense graphs and extending it to sparse graphs. This further demonstrates the power of the pseudo-width method, and we believe it could potentially be useful for attacking also other longstanding open problems for resolution and other proof systems.
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