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| 2. |
- Islam, Fhokrul, et al.
(författare)
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Systematics of electronic and magnetic properties in the transition metal doped Sb2Te3 quantum anomalous Hall platform
- 2018
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Ingår i: Physical Review B. - : American Physical Society. - 2469-9950 .- 2469-9969. ; 97:15
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Tidskriftsartikel (refereegranskat)abstract
- The quantum anomalous Hall effect (QAHE) has recently been reported to emerge in magnetically doped topological insulators. Although its general phenomenology is well established, the microscopic origin is far from being properly understood and controlled. Here, we report on a detailed and systematic investigation of transition metal (TM) doped Sb2Te3. By combining density functional theory calculations with complementary experimental techniques, i.e., scanning tunneling microscopy, resonant photoemission, and x-raymagnetic circular dichroism, we provide a complete spectroscopic characterization of both electronic and magnetic properties. Our results reveal that the TM dopants not only affect the magnetic state of the host material, but also significantly alter the electronic structure by generating impurity-derived energy bands. Our findings demonstrate the existence of a delicate interplay between electronic and magnetic properties in TM doped topological insulators. In particular, we find that the fate of the topological surface states critically depends on the specific character of the TM impurity: while V-and Fe-doped Sb2Te3 display resonant impurity states in the vicinity of the Dirac point, Cr and Mn impurities leave the energy gap unaffected. The single-ion magnetic anisotropy energy and easy axis, which control the magnetic gap opening and its stability, are also found to be strongly TM impurity dependent and can vary from in plane to out of plane depending on the impurity and its distance from the surface. Overall, our results provide general guidelines for the realization of a robust QAHE in TM doped Sb2Te3 in the ferromagnetic state.
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- Proctor, D.N, et al.
(författare)
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Longitudinal changes in physical functional performance among the oldest old: insight from a study of Swedish twins
- 2006
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Ingår i: Aging Clinical and Experimental Research. ; 18:6, s. 517-530
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Tidskriftsartikel (refereegranskat)abstract
- The primary purpose was to characterize mean and individual-level patterns of change in physical functional performance over eight years (2 year intervals) in a community dwelling sample of Swedish twins (579 men and women aged 79-96 years at baseline). RESULTS: Mixed linear models revealed linear rates of decline for handgrip strength (grip) and time to complete five chair stands, and accelerating decline for peak expiratory flow rate (PEFR) for both sexes. Significant random effects were found for intercept and time for grip and PEFR tests, indicating differences between participants initially and over time. Individual differ-ences in chairstand performance were significant for initial status only. Age at baseline was predictive of initial status in grip, PEFR and chair performance (women only), but not rate of change. Measures of body size at baseline were predictive of individual variation in initial grip (height), PEFR (weight in men, height in women), and chair performance (height), but had less consistent associations with changes in test performance over time. In the deceased sub-sample (85% of participants), having been further from death was related to less steep de-clines in grip, but not PEFR or chair performance. Twins from the same pair were related in initial status (twin level variance ~30-70%), but they were not generally related in rate of change. CONCLUSIONS: These results indicate that changes in physical functional perform-ance in an elderly, community dwelling population vary across individuals in a test and sex-dependent manner. Constitutional variables (age, sex, body size) are predictive of baseline performance, but explain little variance in change over time. Initial status and rate of change in grip strength had the strongest association with proximity from death, indicating that while PEFR and repeated chair stand time are useful tests to assess function, grip strength appears to be a particularly useful biomarker in the oldest- old.
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- Braungart Fauth, E, et al.
(författare)
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Physical, cognitive, and psychosocial variables from the Disablement Process Model predict patterns of independence and the transition into disability for the oldest-old
- 2007
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Ingår i: Gerontologist. ; 47:5, s. 613-624
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Tidskriftsartikel (refereegranskat)abstract
- PURPOSE: This study used the Disablement Process Model to predict whether a sample of the oldest-old maintained their disability or disability-free status over a 2- and 4-year follow-up, or whether they transitioned into a state of disability during this time. DESIGN AND METHODS: We followed a sample of 149 Swedish adults who were 86 years of age or older over a period of 4 years; we grouped them by ability in activities of daily living as being functional survivors (nondisabled over time), increasingly disabled (initially nondisabled but later disabled), chronically disabled (disabled at all waves), or deceased. We used variables from baseline to predict group membership into these four longitudinal outcome groups. RESULTS: Results indicated that demographic factors, physical impairments, physical and cognitive limitations, and psychosocial variables at baseline predicted membership into the functional survivor group after 2 years and most continued to distinguish between functional survivors and other groups after 4 years. IMPLICATIONS: These findings indicate key variables that may be useful in predicting shorter term longitudinal changes in disability. By understanding the physical, cognitive, and psychological variables that predict whether a person develops a disability within the next 2 or 4 years, we may be better able to plan for care or implement appropriate interventions.
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| 6. |
- Dahl, Anna, 1975-, et al.
(författare)
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Body Mass Index, Change in Body Mass Index, and Survival in Old and Very Old Persons
- 2013
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Ingår i: Journal of The American Geriatrics Society. - : Wiley. - 0002-8614 .- 1532-5415. ; 61:4, s. 512-518
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Tidskriftsartikel (refereegranskat)abstract
- Objectives To examine how body mass index (BMI) and change in BMI are associated with mortality in old (7079) and very old (80) individuals. Design Pooled data from three multidisciplinary prospective population-based studies: OCTO-twin, Gender, and NONA. Setting Sweden. Participants Eight hundred eighty-two individuals aged 70 to 95. Measurements BMI was calculated from measured height and weight as kg/m2. Information about survival status and time of death was obtained from the Swedish Civil Registration System. Results Mortality hazard was 20% lower for the overweight group than the normalunderweight group (relative risk (RR)=0.80, P=.011), and the mortality hazard for the obese group did not differ significantly from that of the normalunderweight group (RR=0.93, P=.603), independent of age, education, and multimorbidity. Furthermore, mortality hazard was 65% higher for the BMI loss group than for the BMI stable group (RR=1.65, P<.001) and 53% higher for the BMI gain group than for the BMI stable group (RR=1.53, P=.001). Age moderated the BMI change differences. That is, the higher mortality risks associated with BMI loss and gain were less severe in very old age. Conclusion Old persons who were overweight had a lower mortality risk than old persons who were of normal weight, even after controlling for weight change and multimorbidity. Persons who increased or decreased in BMI had a greater mortality risk than those who had a stable BMI, particularly those aged 70 to 79. This study lends further support to the belief that the World Health Organization guidelines for BMI are overly restrictive in old age.
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| 8. |
- Jones, J. W., et al.
(författare)
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Longitudinal correspondence between subjective and objective memory in the oldest old: A parallel process model by gender
- 2019
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Ingår i: European Journal of Ageing. - : Springer Science and Business Media LLC. - 1613-9372 .- 1613-9380. ; 16:3, s. 317-326
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Tidskriftsartikel (refereegranskat)abstract
- Subjective memory and objective memory performance have predictive utility for clinically relevant outcomes in older adults. Previous research supports certain overlap between objective performance and subjective ratings of memory. These studies are typically cross-sectional or use baseline data only to predict subsequent change. The current study uses a parallel process model to examine concurrent changes in objective memory and subjective memory. We combined data from two population-based Swedish studies of individuals aged 80 + years, assessed every 2years (OCTO—3 measurement occasions, OCTO-Twin—5 measurement occasions) yielding 607 participants (66% female). The results confirmed that both objective and subjective memory declined over time. The association between the slope of objective memory and subjective memory was statistically significant for women but not for men. This pattern remained after accounting for age and depressive symptoms. Our findings suggest that, in population-based samples of the oldest old, women seem to show better metacognitive abilities in detecting and reporting changes in memory. Memory changes for men may be better identified by objective performance as their self-assessment of memory changes is not associated with actual change in memory performance. © 2019, Springer Nature B.V.
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