235 research outputs found
Cognitive impairment in older persons with bipolar disorder
No full textBeekman, A.T.F. [Promotor]Stek, M.L. [Copromotor]Comijs, H.C. [Copromotor
Cross cultural comparison of depressive symptoms in Europe does not support sterotypes of aging
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Studies of emittance growth in the ATF
No full textSeveral different mechanisms of emittance growth in the Accelerator Test Facility (ATF) at KEK are investigated: the author calculates rise times of the fast beam-ion instability for the damping ring (DR), and discusses the emittance growth caused by coherent synchrotron radiation in the beam-transport line (BT), the effect of quadrupole wake fields in the injector linac, and, finally, a single-bunch head-tail ion effect that can occur in both the DR and the BT. A first attempt to measure the quadrupole wake on the real machine is also reported
A risk profile for identifying community-dwelling elderly with a highrisk of recurrent falling: results of a 3-year prospective study
No full textIntroduction: The aim of the prospective study reported here was to develop a risk profile that can be used to identify community-dwelling elderly at a high risk of recurrent falling. Materials and methods: The study was designed as a 3-year prospective cohort study. A total of 1365 community-dwelling persons, aged 65 years and older, of the population-based Longitudinal Aging Study Amsterdam participated in the study. During an interview in 1995/1996, physical, cognitive, emotional and social aspects of functioning were assessed. A follow-up on the number of falls and fractures was conducted during a 3-year period using fall calendars that participants filled out weekly. Recurrent fallers were identified as those who fell at least twice within a 6-month period during the 3-year follow-up. Results: The incidence of recurrent falls at the 3-year follow-up point was 24.9% in women and 24.4% in men. Of the respondents, 5.5% reported a total of 87 fractures that resulted from a fall, including 20 hip fractures, 21 wrist fractures and seven humerus fractures. Recurrent fallers were more prone to have a fall-related fracture than those who were not defined as recurrent fallers (11.9% vs. 3.4%; OR: 3.8; 95% CI: 2.3-6.1). Backward logistic regression analysis identified the following predictors in the risk profile for recurrent falling: two or more previous falls, dizziness, functional limitations, weak grip strength, low body weight, fear of falling, the presence of dogs/cats in the household, a high educational level, drinking 18 or more alcoholic consumptions per week and two interaction terms (high educationx18 or more alcohol consumptions per week and two or more previous falls x fear of falling) (AUC=0.71). Discussion: At a cut-off point of 5 on the total risk score (range 0-30), the model predicted recurrent falling with a sensitivity of 59% and a specificity of 71%. At a cut-off point of 10, the sensitivity and specificity were 31% and 92%, respectively. A risk profile including nine predictors that can easily be assessed seems to be a useful tool for the identification of community-dwelling elderly with a high risk of recurrent falling. © International Osteoporosis Foundation and National Osteoporosis Foundation 2006
ATF-4 and hydrogen sulfide signalling mediate longevity from inhibition of translation or mTORC1 [preprint]
No full textThis article is a preprint. Preprints are preliminary reports of work that have not been certified by peer review.
Full author list omitted for brevity. For the full list of authors, see article.Inhibition of mTORC1 (mechanistic target of rapamycin 1) slows ageing, but mTORC1 supports fundamental processes that include protein synthesis, making it critical to elucidate how mTORC1 inhibition increases lifespan. Under stress conditions, the integrated stress response (ISR) globally suppresses protein synthesis, resulting in preferential translation of the transcription factor ATF-4. Here we show in C. elegans that the ATF-4 transcription program promotes longevity and that ATF-4 upregulation mediates lifespan extension from mTORC1 inhibition. ATF-4 activates canonical anti-ageing mechanisms but also increases expression of transsulfuration enzymes to promote hydrogen sulfide (H2S) production. ATF-4-induced H2S production mediates longevity and stress resistance from C. elegans mTORC1 suppression, and ATF4 drives H2S production in mammalian dietary restriction. This H2S boost increases protein persulfidation, a protective modification of redox-reactive cysteines. Increasing H2S levels, or enhancing mechanisms that H2S modulates through persulfidation, may represent promising strategies for mobilising therapeutic benefits of the ISR or mTORC1 inhibition
Psychiatrische diagnostiek: Per definitie gepersonaliseerd = Psychiatric diagnosis: Personalised by definition
No full textComparative study of ATF for a CANDU lattice
No full textMcMaster University MASTER OF APPLIED SCIENCES (2017) Hamilton, Ontario (Engineering Physics)
TITLE: Comparative study of accident-tolerant fuel for a CANDU lattice AUTHOR: Simon Younan, B.Eng. (McMaster University) SUPERVISOR: Dr. David Novog NUMBER OF PAGES: xiii, 120Since the Fukushima accident in 2011, there have been an increasing number of studies on the use of accident-tolerant fuel (ATF) in light water reactors to mitigate the consequences of a future severe accident, by better retaining fission products and/or providing operators more time to implement emergency measures.
However, few studies exist for CANDU reactors in this regard. The goal of this study is to determine how different types of ATF are expected to behave in a CANDU lattice when compared to the current UO2 fuels. In particular, this study focuses on neutronic parameters calculated using the Serpent 2 code, but also models heat transfer and stylized accident scenarios. The ATF concepts tested include UO2-SiC composites, UN and UN-based composites, U-9Mo, and fully ceramic microencapsulated (FCM) fuel, along with SiC and SS-coated cladding. Four general conclusions can be drawn:
1. Fuel temperature are lower for ATF as compared to traditional fuels. UO2-SiC composite fuel exhibits a moderate temperature reduction compared to UO2, particularly for fresh fuel. Other ATF fuel materials exhibit a substantial decrease in fuel temperature compared to UO2. The lower fuel temperatures are also accompanied by lower melting temperatures for some fuels, hence each design requires specific assessments on safety.
2. As most ATF have a poorer neutron economy compared to standard fuel designs, enrichment is required to use ATF in a CANDU, particularly for UN and FCM fuel compositions. Coolant void reactivity (CVR) is lowest with FCM fuel and highest with U-9Mo fuel. Fuel temperature coefficient (FTC) is most negative for fuel containing UN or U-9Mo.
3. Changing the cladding material from zircaloy to SiC slightly improves neutron economy, while a FeCrAl surface layer impairs neutron economy. The impact of many ATF sheath materials is to greatly reduce or eliminate hydrogen production in some severe accidents. A specific assessment on hydrogen production was not performed in this study.
4. In stylized accident scenarios, all fuels exhibit only a small temperature spike due to the reactivity insertion of the LOCA as the reactor shutdown limits the power excursion. For cases where Emergency Core Cooling functions as designed, fuel and channel failures are precluded for both traditional fuels and ATF. For cases with impairment of ECC, most ATF fuels show lower fuel temperatures than UO2 fuels and adequate heat removal to the pressure-calandria tube fuel channel. The exception would be Mo-based fuels that reach the melting point prior to establishing an adequately high sheath temperature to sustain radiative heat removal to the PT-CT assembly.ThesisMaster of Applied Science (MASc)Since the Fukushima accident in 2011, there have been an increasing number of studies on the use of accident-tolerant fuel in nuclear reactors to mitigate the consequences of a future severe accident, reducing the likelihood and severity of a radiation release. Canadian reactors are of the CANDU design, which differs greatly from the reactors most recent studies have focused on. The goal of this study is to determine the feasibility of using accident-tolerant fuel in CANDU reactors, studying different types.
In general, the goal of accident-tolerant fuels in CANDU reactors would be to reduce fuel temperatures and improve fission product retention, reducing the likelihood/magnitude of radioactive releases in a severe accident. However, nearly all types of accident-tolerant fuel would also require the uranium to be slightly enriched as opposed to the current fuel which is based on naturally-occurring uranium. This study outlines the results obtained by computer modelling of accident-tolerant fuel in a CANDU reactor, including the enrichment requirements, changes to important reactivity feedbacks, and impacts on accident performance
Psychiatrische diagnostiek: Per definitie gepersonaliseerd = Psychiatric diagnosis: Personalised by definition
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