| 231. |
- Gustafsson, Stefan, et al.
(författare)
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Electromagnetic dispersion modeling and measurements for HVDC power cables
- 2014
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Ingår i: IEEE Transactions on Power Delivery. - : IEEE Press. - 0885-8977 .- 1937-4208. ; 29:6, s. 2439-2447
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Tidskriftsartikel (refereegranskat)abstract
- This paper provides a general framework for electromagnetic (EM) modeling, sensitivity analysis, computation, and measurements regarding the wave propagation characteristics of high-voltage direct-current (HVDC) power cables. The modeling is motivated by the potential use with transient analysis, partial-discharge measurements, fault localization and monitoring, and is focused on very long (10 km or more) HVDC power cables with transients propagating in the low-frequency regime of about 0-100 kHz. An exact dispersion relation is formulated together with a discussion on practical aspects regarding the computation of the propagation constant. Experimental time-domain measurement data from an 80-km-long HVDC power cable are used to validate the electromagnetic model, and a mismatch calibration procedure is devised to account for the connection between the measurement equipment and the cable. Quantitative sensitivity analysis is devised to study the impact of parameter uncertainty on wave propagation characteristics. The sensitivity analysis can be used to study how material choices affect the propagation characteristics, and to indicate which material parameters need to be identified accurately in order to achieve accurate fault localization. The analysis shows that the sensitivity of the propagation constant due to a change in the conductivity in the three metallic layers (the inner conductor, the intermediate lead shield, and the outer steel armor) is comparable to the sensitivity with respect to the permittivity of the insulating layer. Hence, proper modeling of the EM fields inside the metallic layers is crucial in the low-frequency regime of 0-100 kHz.
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| 232. |
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| 233. |
- Gustafsson, Susanne, et al.
(författare)
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Swedish health care professionals' view of frailty in older persons
- 2012
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Ingår i: Journal of Applied Gerontology. - : Sage Publications. - 0733-4648 .- 1552-4523. ; 31:5, s. 622-640
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Tidskriftsartikel (refereegranskat)abstract
- There is a paucity of research literature concerning frailty in older persons from the health care professionals' perspective. Consequently, the purpose of this study was to elucidate health care professionals' view of frailty in older persons. An explorative, qualitative design was selected and four focus groups comprising 21 health care professionals were conducted, audiotaped, transcribed verbatim, and analyzed. Frailty was found to consist of seven dimensions: "being bodily weak and ill," "being negatively influenced by personal qualities," "lacking balance in everyday activities," "being dependent in everyday life," "not being considered important," "being hindered by the physical milieu and defective community service," and "having an inadequate social network." The results showed that health care professionals' view of frailty in older persons differed from the current state of knowledge on frailty. This implies that the seven dimensions found to constitute frailty could contribute to a more comprehensive understanding of the concept.
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| 234. |
- Görman, Ulf, et al.
(författare)
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Ethical Considerations in Nutrigenetics and Nutrigenomics
- 2020
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Ingår i: Principles of Nutrigenetics and Nutrigenomics : Fundamentals for Individualized Nutrition - Fundamentals for Individualized Nutrition. - London : Elsevier. - 9780128045725 - 9780128045879 ; , s. 543-548
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Bokkapitel (refereegranskat)abstract
- Ethics is the study of the normative dimensions of human relations and experiences. This chapter discusses such questions in relation to basic values in modern society. The normative foundations for the analysis are the values of human dignity, autonomy, freedom, equality, and solidarity, as well as the responsibilities of society toward its citizens, including freedom, security, and justice. The questions that are brought up touch on how implementing nutrigenetics and nutrigenomics in personalized nutrition services relates to these values.Health and food are primary human needs. The choice of food can contribute to the support of health, but it can also come into conflict with health. Personalized nutrition may be seen as part of a wider trend toward early preventive actions to treat susceptibility to disease. If personalization of nutrition can contribute to eating habits that support health instead of threatening it, this will be beneficial for the individual, but it may also be good for society as a whole. As a consequence, pressure on societal expenses for health care may be reduced.Personalized nutrition, as well as the wider concept of precision nutrition, have stimulated expectations and are often described as having great potential, but it has also been difficult to realize them. Studies indicate that there is widespread optimism among researchers engaged in nutrigenetics and nutrigenomics regarding at least its long-term benefits, whereas there are divergent viewpoints within the wider research community. In this situation, ethical concerns need to receive attention.
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| 235. |
- Hacker, R Scott, et al.
(författare)
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A Test for Multivariate ARCH Effects
- 2005
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Ingår i: Applied Economics Letters. - : Informa UK Limited. - 1350-4851 .- 1466-4291. ; 12:7, s. 411-417
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Tidskriftsartikel (refereegranskat)abstract
- This paper extends Engle's LM test for ARCH affects to multivariate cases. The size and power properties of this multivariate test for ARCH effects in VAR models are investigated based on asymptotic and bootstrap distributions. Using the asymptotic distribution, deviations of actual size from nominal size do not appear to be very excessive. Nevertheless, there is a tendency for the actual size to overreject the null hypothesis when the nominal size is 1% and underreject the null when the nominal size is 5% or 10%. It is found that using a bootstrap distribution for the multivariate LM test is generally superior in achieving the appropriate size to using the asymptotic distribution when (1) the nominal size is 5%; (2) the sample size is small (40 observations) and/or the VAR system is stable. With a small sample, the power of the test using the bootstrap distribution also appears better at the 5% nominal size.
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| 236. |
- Hacker, R Scott, 1964-, et al.
(författare)
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Optimal lag-length choice in stable and unstable VAR models under situations of homoscedasticity and ARCH
- 2008
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Ingår i: Journal of Applied Statistics. - : Routledge. - 0266-4763 .- 1360-0532. ; 35:6, s. 601-615
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Tidskriftsartikel (refereegranskat)abstract
- The performance of different information criteria - namely Akaike, corrected Akaike (AICC), Schwarz-Bayesian (SBC), and Hannan-Quinn - is investigated so as to choose the optimal lag length in stable and unstable vector autoregressive (VAR) models both when autoregressive conditional heteroscedasticity (ARCH) is present and when it is not. The investigation covers both large and small sample sizes. The Monte Carlo simulation results show that SBC has relatively better performance in lag-choice accuracy in many situations. It is also generally the least sensitive to ARCH regardless of stability or instability of the VAR model, especially in large sample sizes. These appealing properties of SBC make it the optimal criterion for choosing lag length in many situations, especially in the case of financial data, which are usually characterized by occasional periods of high volatility. SBC also has the best forecasting abilities in the majority of situations in which we vary sample size, stability, variance structure (ARCH or not), and forecast horizon (one period or five). frequently, AICC also has good lag-choosing and forecasting properties. However, when ARCH is present, the five-period forecast performance of all criteria in all situations worsens.
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| 237. |
- Hacker, R Scott, et al.
(författare)
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Tests for Causality between Integrated Variables Using Asymptotic and Bootstrap Distributions : Theory and Application
- 2006
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Ingår i: Applied Economics. - : Informa UK Limited. - 0003-6846 .- 1466-4283. ; 38:13, s. 1489-1500
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Tidskriftsartikel (refereegranskat)abstract
- Causality tests in the Granger's sense are increasingly applied in empirical research. Since the unit root revolution in time-series analysis, several modifications of tests for causality have been introduced in the literature. One of the recent developments is the Toda-Yamamoto modified Wald (MWALD) test, which is attractive due to its simple application, its absence of pre-testing distortions, and its basis on a standard asymptotical distribution irrespective of the number of unit roots and the cointegrating properties of the data. This study investigates the size properties of the MWALD test and finds that in small sample sizes this test performs poorly on those properties when using its asymptotical distribution, the chi-square. It is suggested that use be made of a leveraged bootstrap distribution to lower the size distortions. Monte Carlo simulation results show that an MWALD test based on a bootstrap distribution has much smaller size distortions than corresponding cases when the asymptotic distribution is used. These results hold for different sample sizes, integration orders, and error term processes (homoscedastic or ARCH). This new method is applied to the testing of the efficient market hypothesis
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| 238. |
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| 239. |
- Hallgren, Jenny, 1978-, et al.
(författare)
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Factors associated with increased hospitalisation risk among nursing home residents in Sweden : a prospective study with a three-year follow-up
- 2016
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Ingår i: International Journal of Older People Nursing. - : John Wiley & Sons. - 1748-3735 .- 1748-3743. ; 11:2, s. 130-139
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Tidskriftsartikel (refereegranskat)abstract
- BackgroundHospitalisation of nursing home residents might lead to deteriorating health.AimTo evaluate physical and psychological factors associated with hospitalisation risk among nursing home residents.DesignProspective study with three years of follow-up.MethodsFour hundred and twenty-nine Swedish nursing home residents, ages 65–101 years, from 11 nursing homes in three municipalities were followed during three years. The participants' physical and psychological status was assessed at baseline. A Cox proportional hazards model was used to evaluate factors associated with hospitalisation risk using STATA.ResultsOf the 429 participants, 196 (45.7%) were hospitalised at least once during the three-year follow-up period, and 109 (25.4%) during the first six months of the study. The most common causes of hospitalisation were cardiovascular diseases or complications due to falls. A Cox regression model showed that residents who have had previous falls (P < 0.001), are malnourished (P < 0.001), use a greater number of drugs (P < 0.001) and have more diseases (P < 0.001), are at an increased risk of hospitalisation.ConclusionNursing home residents are frequently hospitalised, often due to falls or cardiovascular diseases. Study results underscore the relationships between malnutrition, previous falls, greater numbers of drugs and diseases and higher risk of hospitalisation.Implications for practicePreventive interventions aimed at malnutrition and falls at the nursing home could potentially reduce the number of hospitalisations. With improved education and support to nurses concerning risk assessment at the nursing homes, it may be possible to reduce the numbers of avoidable hospitalisation among nursing home residents and in the long run improve quality of life and reduce suffering.
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| 240. |
- Hallgren, Mats, et al.
(författare)
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Exercise and internet-based cognitive-behavioural therapy for depression : Multicentre randomized controlled trial with 12-month follow-up
- 2016
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Ingår i: British Journal of Psychiatry. - : Cambridge University Press. - 0007-1250 .- 1472-1465. ; 209:5, s. 414-420
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Tidskriftsartikel (refereegranskat)abstract
- Background Evidence-based treatment of depression continues to grow, but successful treatment and maintenance of treatment response remains limited.Aims To compare the effectiveness of exercise, internet-based cognitive-behavioural therapy (ICBT) and usual care for depression.Method A multicentre, three-group parallel, randomised controlled trial was conducted with assessment at 3 months (posttreatment) and 12 months (primary end-point). Outcome assessors were masked to group allocation. Computer-generated allocation was performed externally in blocks of 36 and the ratio of participants per group was 1:1:1. In total, 945 adults with mild to moderate depression aged 18-71 years were recruited from primary healthcare centres located throughout Sweden. Participants were randomly assigned to one of three 12-week interventions: supervised group exercise, clinician-supported ICBT or usual care by a physician. The primary outcome was depression severity assessed by the Montgomery-Åsberg Depression Rating Scale (MADRS).Results The response rate at 12-month follow-up was 84%. Depression severity reduced significantly in all three treatment groups in a quadratic trend over time. Mean differences in MADRS score at 12 months were 12.1 (ICBT), 11.4 (exercise) and 9.7 (usual care). At the primary end-point the group x time interaction was significant for both exercise and ICBT. Effect sizes for both interventions were small to moderate.Conclusions The long-term treatment effects reported here suggest that prescribed exercise and clinician-supported ICBT should be considered for the treatment of mild to moderate depression in adults.
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