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Evaluating the impact of muon-induced cosmogenic 39Ar and 37Ar underground production on groundwater dating with field observations and numerical modeling.
No full textGroundwater dating by radioactive cosmogenic tracers such as 39Ar relies on the decay rate from a known initial atmospheric activity (100%modern). Thereby, it is assumed that cosmogenic 39Ar production in the subsurface is negligible at depths below the water table and that contributions from natural rock radioactivity are minor or missing. Here we present 39Ar data from aquifers located in quaternary glacial sediments and tertiary limestones in Denmark, which unequivocally demonstrate that cosmogenic production can induce considerable age biases. 39Ar values larger than 100%modern are observed at relatively shallow groundwater depths in non-radiogenic rocks. These activities are compared to calculations based on previously assessed depth-dependent production rates in rocks and realistic estimates of the emanated fractions to the water phase. The water residence time distribution with depth, which was determined by numerical flow modeling and particle tracking, underpinned the significance of muon-induced 39Ar production. The short-lived isotope 37Ar is produced by similar processes as 39Ar and demonstrated its usefulness as an indicator of local underground production in an aquifer. The significance of cosmogenic underground production in other possible recharge scenarios was then assessed by explicitly simulating the radioargon accumulation and decay in a 2D synthetical numerical model. These simulations demonstrated that underground production is negligible when the water infiltrates freely in a porous aquifer. However, in the presence of a confining layer impeding the infiltration at shallow depths (100%modern) may occur. The age concluded from the dissolved activities is then possibly biased towards young values. Special attention should thus be paid to the recharge rates when using 39Ar for dating groundwater. 37Ar activities provide complementary information about the strength and mechanisms of underground production
In situ synchrotron radiation μCT indentation of cortical bone: Anisotropic crack propagation, local deformation, and fracture.
No full textThe development of treatment strategies for skeletal diseases relies on the understanding of bone mechanical properties in relation to its structure at different length scales. At the microscale, indention techniques can be used to evaluate the elastic, plastic, and fracture behaviour of bone tissue. Here, we combined in situ high-resolution SRμCT indentation testing and digital volume correlation to elucidate the anisotropic crack propagation, deformation, and fracture of ovine cortical bone under Berkovich and spherical tips. Independently of the indenter type we observed significant dependence of the crack development due to the anisotropy ahead of the tip, with lower strains and smaller crack systems developing in samples indented in the transverse material direction, where the fibrillar bone ultrastructure is largely aligned perpendicular to the indentation direction. Such alignment allows to accommodate the strain energy, inhibiting crack propagation. Higher tensile hoop strains generally correlated with regions that display significant cracking radial to the indenter, indicating a predominant Mode I fracture. This was confirmed by the three-dimensional analysis of crack opening displacements and stress intensity factors along the crack front obtained for the first time from full displacement fields in bone tissue. The X-ray beam significantly influenced the relaxation behaviour independent of the tip. Raman analyses did not show significant changes in specimen composition after irradiation compared to non-irradiated tissue, suggesting an embrittlement process that may be linked to damage of the non-fibrillar organic matrix. This study highlights the importance of three-dimensional investigation of bone deformation and fracture behaviour to explore the mechanisms of bone failure in relation to structural changes due to aging or disease. STATEMENT OF SIGNIFICANCE: : Characterising the three-dimensional deformation and fracture behaviour of bone remains essential to decipher the interplay between structure, function, and composition with the aim to improve fracture prevention strategies. The experimental methodology presented here, combining high-resolution imaging, indentation testing and digital volume correlation, allows us to quantify the local deformation, crack propagation, and fracture modes of cortical bone tissue. Our results highlight the anisotropic behaviour of osteonal bone and the complex crack propagation patterns and fracture modes initiating by the intricate stress states beneath the indenter tip. This is of wide interest not only for the understanding of bone fracture but also to understand other architectured (bio)structures providing an effective way to quantify their toughening mechanisms in relation to their main mechanical function
Correction to: Low-dose radiotherapy for greater trochanteric pain syndrome-a single-centre analysis.
Get PDFSleep Capital: Linking Brain Health to Wellbeing and Economic Productivity Across the Lifespan.
No full textINTRODUCTION AND FRAMEWORK
Sleep capital contributes to individual and societal wellbeing, productivity, and economic outcomes and involves a novel aspect of brain capital. It encompasses the quality and quantity of sleep as integral components that influence cognitive abilities, mental and brain health, and physical health, affecting workplace productivity, learning, decision-making, and overall economic performance. Here, we bring a framework to understand the complex relationship between sleep quality, health, wellbeing, and economic productivity. Then we outline the multilevel impact of sleep on cognitive abilities, mental/brain health, and economic indicators, providing evidence for the substantial returns on investment in sleep health initiatives. Moreover, sleep capital is a key factor when considering brain health across the lifespan, especially for the aging population.
DISCUSSION
We propose specific elements and main variables to develop specific indexes of sleep capital to address its impacts on health, wellbeing and productivity.
CONCLUSION
Finally, we suggest policy recommendations, workplace interventions, and individual strategies to promote sleep health and brain capital. Investing in sleep capital is essential for fostering a healthier, happier, fairer and more productive society
An enzymatically crosslinked collagen type II/hyaluronic acid hybrid hydrogel: A biomimetic cell delivery system for cartilage tissue engineering.
No full textThis study presents new injectable hydrogels based on hyaluronic acid and collagen type II that mimic the polysaccharide-protein structure of natural cartilage. After collagen isolation from chicken sternal cartilage, tyramine-grafted hyaluronic acid and collagen type II (HA-Tyr and COL-II-Tyr) were synthesized. Hybrid hydrogels were prepared with different ratios of HA-Tyr/COL-II-Tyr using horseradish peroxidase and noncytotoxic concentrations of hydrogen peroxide to encapsulate human bone marrow-derived mesenchymal stromal cells (hBM-MSCs). The findings showed that a higher HA-Tyr content resulted in a higher storage modulus and a lower hydrogel shrinkage, resulting in hydrogel swelling. Incorporating COL-II-Tyr into HA-Tyr hydrogels induced a more favorable microenvironment for hBM-MSCs chondrogenic differentiation. Compared to HA-Tyr alone, the hybrid HA-Tyr/COL-II-Tyr hydrogel promoted enhanced chondrocyte adhesion, spreading, proliferation, and upregulation of cartilage-related gene expression. These results highlight the promising potential of injectable HA-Tyr/COL-II-Tyr hybrid hydrogels to deliver cells for cartilage regeneration
Comparing DAPSA, DAPSA28 and DAS28-CRP in patients with psoriatic arthritis initiating a first TNF-inhibitor across nine European countries.
No full textObjectives: Since 66/68 joint counts are not always performed in routine care, we aimed to determine which of a. the modified 28‐joint disease activity index for psoriatic arthritis (DAPSA28), or b. 28‐joint disease activity score with C‐reactive protein (DAS28‐CRP) should be preferred for monitoring disease activity in psoriatic arthritis (PsA), when the original DAPSA (66/68 joints) is not available.
Methods: Prospectively collected real‐world data of European bio‐naïve PsA patients initiating a first tumor necrosis factor inhibitor (TNFi) were pooled. Remission and response status were evaluated at 6 months by: remission; DAPSA≤4, DAPSA28≤4, DAS28‐CRP<2.6, response; 75% improvement for DAPSA and DAPSA28, and combined EULAR good/moderate responses for DAS28‐CRP. Logistic regression analyses on multiple imputed data were used to identify baseline predictors.
Results: Remission and response cohorts included 3,159 and 1,866 patients, respectively. Six‐month proportions achieving remission/response were: DAPSA: 27%/44%, DAPSA28: 28%/44% and DAS28‐CRP: 59%/80%. Of 14 possible baseline predictors, 11 predicted both DAPSA and DAPSA28 remission, (eight of which also predicted their response, indicated by*): longer disease duration*, male sex* and higher CRP* were positive, while older age*, higher body mass index*, patient fatigue* and global, physician global, health assessment questionnaire score*, tender and swollen* joint counts were negative predictors. Eight and five of these predicted DAS28‐CRP remission and response, respectively.
Conclusion: In patients with PsA, DAPSA28 should be preferred over DAS28‐CRP as a substitute for DAPSA when 66/68 joint counts are not available, due to the large overlap in remission and response status and in predictors between DAPSA and DAPSA28
Risk factors for falls among hospitalized medical patients - A systematic review and meta-analysis.
Get PDFOBJECTIVE
To identify and quantify risk factors for in-hospital falls in medical patients.
DATA SOURCES
Six databases (MEDLINE, Embase, Cochrane Database of Systematic Reviews, Cochrane Central Register of Controlled Trials, CINAHL, and Google Scholar) were systematically screened until April 11, 2023, to identify relevant articles.
STUDY SELECTION
All titles and abstracts of the retrieved articles were independently screened by two researchers who also read the full texts of the remaining articles. Quantitative studies that assessed risk factors for falls among adult patients acutely hospitalized were included in the review. Publications that did not capture internal medicine patients or focused on other specific populations were excluded.
DATA EXTRACTION
Information on study characteristics and potential risk factors were systematically extracted. Risk of bias was assessed using the Quality in Prognosis Studies (QUIPS) tool. PRISMA and MOOSE guidelines were followed for reporting.
DATA SYNTHESIS
The main outcome was any in-hospital falls. Using a random-effects meta-analysis model, association measures for each risk factor reported in five or more studies were pooled. Separate analyses according to effect measure and studies adjusted for sex and age at least were performed. Of 5,067 records retrieved, 119 original publications from 25 countries were included. In conclusion, 23 potential risk factors were meta-analyzed. Strong evidence with large effect sizes was found for a history of falls (OR 2.54; 95% CI 1.63- 3.96; I2 91%), antidepressants (pooled OR 2.25; 95% confidence interval [95% CI] 1.92-2.65; I2 0%), benzodiazepines (OR 1.97; 95% CI 1.68-2.31; I2 0%), hypnotics-sedatives (OR 1.90; 95% CI 1.53-2.36; I2 46%), and antipsychotics (OR 1.61; 95% CI 1.33-1.95; I2 0%). Furthermore, evidence of associations with male sex (OR 1.22, 95% CI 0.99-1.50, I2 65%) and age (OR 1.17, 95% CI 1.02-1.35, I2 72%) were found, but effect sizes were small.
CONCLUSIONS
The comprehensive list of risk factors, which specifies the strength of evidence and effect sizes, could assist in the prioritization of preventive measures and interventions
Fracture prediction in a Swiss cohort.
No full textFracture prediction is essential in managing patients with osteoporosis, and is an integral component of many fracture prevention guidelines. We aimed to identify the most relevant clinical fracture risk factors in contemporary populations by training and validating short- and long-term fracture risk prediction models in two cohorts. We used traditional and machine learning survival models to predict risks of vertebral, hip and any fractures on the basis of clinical risk factors, T-scores and treatment history among participants in a nationwide Swiss osteoporosis registry (N = 5944 postmenopausal women, median follow-up of 4.1 years between January 2015 and October 2022; a total of 1190 fractures during follow-up). The independent validation cohort comprised 5474 postmenopausal women from the UK Biobank with 290 incident fractures during follow-up. Uno's C-index and the time-dependent area under the receiver operating characteristics curve were calculated to evaluate the performance of different machine learning models (Random survival forests and eXtreme Gradient Boosting). In the independent validation set, the C-index was 0.74 [0.58, 0.86] for vertebral fractures, 0.83 [0.7, 0.94] for hip fractures and 0.63 [0.58, 0.69] for any fractures at year 2, and these values further increased for longer estimations of up to 7 years. In comparison, the 10-year fracture probability calculated with FRAX® Switzerland was 0.60 [0.55, 0.64] for major osteoporotic fractures and 0.62 [0.49, 0.74] for hip fractures. The most important variables identified with Shapley additive explanations (SHAP) values were age, T-scores and prior fractures, while number of falls was an important predictor of hip fractures. Performances of both traditional and machine learning models showed similar C-indices. We conclude that fracture risk can be improved by including the lumbar spine T-score, trabecular bone score, numbers of falls and recent fractures, and treatment information has a significant impact on fracture prediction
Error climate and alienation from teachers: A longitudinal analysis in primary school.
Get PDFBACKGROUND
Dealing with errors in the classroom is a crucial aspect of instructional quality and has multiple consequences for students' own dealing with errors, their learning and their achievement. The available literature on error climate indicates a paucity of research on the effects of perceived error climate on social aspects such as student-teacher relationships.
AIMS
The aim of this longitudinal study was to examine the relationship between error climate and alienation from teachers.
SAMPLES
We conducted a study with two measurement points in primary school (Grade 5 in 2017 and Grade 6 in 2018) and two samples (N = 406 students in 29 classes in Switzerland and N = 345 students in 39 classes in Luxembourg).
METHODS
For scrutinizing the effect of error climate at T1 on alienation from teachers at T2, we used hierarchical linear modelling (students nested within classrooms).
RESULTS
For both samples, the results indicated that a positive error climate at T1 predicted less alienation from teachers at T2. We also found an effect of the shared error climate on alienation from teachers.
CONCLUSIONS
The findings provide empirical evidence of the importance of improving how errors are handled in the classroom to prevent students' alienation from their teachers
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