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| 2. |
- Hegre, Håvard, 1964-, et al.
(författare)
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Can We Predict Armed Conflict? : How the First 9 Years of Published Forecasts Stand Up to Reality
- 2021
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Ingår i: International Studies Quarterly. - : Oxford University Press. - 0020-8833 .- 1468-2478. ; 65:3, s. 660-668
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Tidskriftsartikel (refereegranskat)abstract
- Can we predict civil war? This article sheds light on this question by evaluating 9 years of, at the time, future predictions made by Hegre et al. (2013) in 2011. We evaluate the ability of this study to predict observed conflicts in the 2010–2018 period, using multiple metrics. We also evaluate the original performance evaluation, i.e., whether the performance measures presented by Hegre et al. hold in this new 9-year window. Overall, we conclude that Hegre et al. were able to produce meaningful and reasonably accurate predictions of armed conflict. Of course, they did not always hit the mark. We find that the model has performed worse in predicting low level incidence of conflict than in predicting major armed conflict. The model also failed to predict some important broader regional shifts. These, however, represent important insights for future research and illustrate the utility in predictive models for both testing and developing theory.
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| 3. |
- Langmann, Edwin
(författare)
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An explicit solution of the (quantum) elliptic Calogero-Sutherland model
- 2005
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Ingår i: SPT 2004. - : WORLD SCIENTIFIC. - 9812560912 ; , s. 159-174
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Konferensbidrag (refereegranskat)abstract
- We present explicit formulas for the eigenvalues and eigenfunctions of the elliptic Calogero-Sutherland (eCS) model as formal power series to all orders in the nome of the elliptic functions, for arbitrary values of the (positive) coupling constant and particle number. Our solution gives explicit formulas for an elliptic deformation of the Jack polynomials.
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| 5. |
- Anveden Berglind, I, et al.
(författare)
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Occupational skin exposure to water : a population-based study.
- 2008
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Ingår i: The British journal of dermatology. - : Oxford University Press (OUP). - 1365-2133 .- 0007-0963.
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Tidskriftsartikel (refereegranskat)abstract
- Background Occupational exposure to skin irritants, in particular to water, is an important risk factor for hand eczema. Objectives To assess occupational skin exposure to water in the general population. Methods As part of a public health survey in Stockholm, Sweden, 18 267 gainfully employed individuals aged 18-64 years completed a questionnaire with previously validated questions regarding occupational skin exposure to water. Results Altogether 16% reported exposure to water for (1/2) h or more a day, and 13% reported exposure to water more than 10 times a day. Furthermore, 7% reported water exposure of more than 2 h and 6% of more than 20 times a day. Women reported more water exposure than men and many female-dominated occupations were seen to comprise water exposure. Women were also more exposed than men within the same jobs. Young adults were more exposed than older. A total of 18% were employed in high-risk occupations for hand eczema. Fifty-nine per cent of individuals employed in high-risk occupations reported water exposure at work, compared with 11% in low-risk occupations. Conclusions A total of 20% of the population of working age acknowledged occupational skin exposure to water, which was found to be more common in young adults and women. Using job title as a proxy for water exposure gives an underestimation due to misclassification. In assessing occupational skin exposure to water, both exposure time and frequency should be considered.
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- Barber, J.R., et al.
(författare)
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Shakedown in frictional contact problems
- 2007
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Ingår i: 2007 Proceedings of the ASME/STLE International Joint Tribology Conference. - 0791838110 - 0791848108 ; , s. 517-519
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- If a linear elastic system with frictional interfaces is subjected to periodic loading, any slip which occurs generally reduces the tendency to slip during subsequent cycles and in some circumstances the system ‘shakes down’ to a state without slip. It has often been conjectured that a frictional Melan’s theorem should apply to this problem — i.e. that the existence of a state of residual stress sufficient to prevent further slip is a sufficient condition for the system to shake down. Here we discuss recent proofs that this is indeed the case for ‘complete’ contact problems if there is no coupling between relative tangential displacements at the interface and the corresponding normal contact tractions. By contrast, when coupling is present, the theorem applies only for a few special two-dimensional discrete cases. Counter-examples can be generated for all other cases. These results apply both in the discrete and the continuum formulation.
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| 8. |
- Bentayeb, M, et al.
(författare)
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Adverse respiratory effects of outdoor air pollution in the elderly
- 2012
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Ingår i: The International Journal of Tuberculosis and Lung Disease. - : International Union Against Tuberculosis and Lung Disease. - 1027-3719 .- 1815-7920. ; 16:9, s. 1149-1161
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Tidskriftsartikel (refereegranskat)abstract
- Compared to the rest of the population, the elderly are potentially highly susceptible to the effects of outdoor air pollution due to normal and pathological ageing. The purpose of the present review was to gather data on the effects on respiratory health of outdoor air pollution in the elderly, on whom data are scarce. These show statistically significant short-term and chronic adverse effects of various outdoor air pollutants on cardiopulmonary morbidity and mortality in the elderly. When exposed to air pollution, the elderly experience more hospital admissions for asthma and chronic obstructive pulmonary disease (COPD) and higher COPD mortality than others. Previous studies also indicate that research on the health effects of air pollution in the elderly has been affected by methodological problems in terms of exposure and health effect assessments. Few pollutants have been considered, and exposure assessment has been based mostly on background air pollution and more rarely on objective measurements and modelling. Significant progress needs to be made through the development of 'hybrid' models utilising the strengths of information on exposure in various environments to several air pollutants, coupled with daily activity exposure patterns. Investigations of chronic effects of air pollution and of multi-pollutant mixtures are needed to better understand the role of air pollution in the elderly. Lastly, smoking, occupation, comorbidities, treatment and the neighbourhood context should be considered as confounders or modifiers of such a role. In this context, the underlying biological, physiological and toxicological mechanisms need to be explored to better understand the phenomenon through a multidisciplinary approach.
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| 9. |
- Brandau, Benedikt
(författare)
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Spectral analysis in laser powder bed fusion
- 2022
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This thesis is about the investigation of the spectral interaction of electromagnetic radiation with metal powders. For this purpose, spectral data of powders for laser powder bed fusion processes are investigated in three papers using different techniques. In paper A the spectral radiation behavior of the laser interaction zone is considered, in paper B and C the absorbance behavior of different metal powders depending on their state and measurement method. Paper A investigates the spectral signal of the process light generated by laser material interaction in laser powder bed fusion. The detection is performed by a coaxially guided measuring beam and a quasi-coaxial measuring beam simultaneously guided by another scanning optics. The signal characteristics depend on the angle of incidence of the measuring beam to the laser material interaction zone. Using high-speed recordings and optical simulations, a model for describing the signal behavior could be determined. The measured spectral intensity distribution representing the degree for energy coupling can be corrected with a correction factor over the whole field for solid materials. This correction includes a function describing the numerical aperture of the measuring channel and the laser intensity on the working field. For the investigated powder, the measurement signal fluctuated strongly and no transferable model could be formed. The reason for this was the different absorbance behavior of the powders investigated. Paper B therefore deals in detail with the spectral absorbance behavior of metal powders for additive manufacturing. Using a high-precision spectrometer, 39 powders were measured reflectively over a wide spectral range and the absorbance determined. By varying the degree of use, aging, grain size and impurities, various influence parameters are determined experimentally and discussed theoretically. Based on 20 derived laser wavelengths, technically usable wavelengths with better process efficiency and stability are proposed. From the obtained absorbance, the efficiency of energy coupling can be estimated and form a broad data base for the optimization of laser parameters. In order to perform the absorbance determinations also in situ in a laser powder bed fusion system paper C describes a possibility of an inline absorbance determination by high resolution coaxial imaging. A method is discussed for geometrically correct and gapless imaging of the processing plane, recorded through the laser optics. By imaging at six different wavelengths, metal powders can be distinguished by their absorbance spectrum and impurities can be detected. In an experimental implementation the functionality of the method is proven. The results are validated by optical simulations, ray tracing and comparative measurements with a high-precision spectrometer.
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