Hysteresis, Avalanches, and Noise: Numerical Methods

In studying the avalanches and noise in a model of hysteresis loops we have developed two relatively straightforward algorithms which have allowed us to study large systems efficiently. Our model is the random-field Ising model at zero temperature, with deterministic albeit random dynamics. The first algorithm, implemented using sorted lists, scales in computer time as O(N log N), and asymptotically uses N (sizeof(double)+ sizeof(int)) bits of memory. The second algorithm, which never generates the random fields, scales in time as O(N \log N) and asymptotically needs storage of only one bit per spin, about 96 times less memory than the first algorithm. We present results for system sizes of up to a billion spins, which can be run on a workstation with 128MB of RAM in a few hours. We also show that important physical questions were resolved only with the largest of these simulations

The perception of food products in adolescents, lay adults, and experts: A psychometric approach

Almost 40% of global mortality is attributable to an unhealthy diet, and adolescents and young adults are particularly affected by growing obesity rates. How do (young) people conceptualize and judge the healthiness of foods and how are the judgments embedded in people’s mental representations of the food ecology? We asked respondents to rate a large range of common food products on a diverse set of characteristics and then applied the psychometric paradigm to identify the dimensions structuring people’s mental representations of the foods. Respondents were also asked to rate each food in terms of its healthiness, and we used the foods’ scores on the extracted dimensions to predict the healthiness judgments. We compared three groups of respondents: adolescents, lay adults, and nutrition experts. Naturalness levels (e.g., processing, artificial additives) and cholesterol and protein content emerged as the two central dimensions structuring respondents’ mental representations of the foods. Relative to the other two groups, the adolescents’ representations were less differentiated. Judged food healthiness was determined by multiple factors, but naturalness was the strongest predictor across all groups. Overall, the adolescents’ responses showed considerable heterogeneity, suggesting a lack of solid food knowledge and the need for tailored nutrition education on specific food products and content characteristics.publishedVersionPaid open acces

Simulation of throttle flow with two phase and single phase homogenous equilibrium model

This paper aims to compare the results of two commonly used methods for the simulation of cavitating flows; one is the two phase mass transfer approach and the other is a homogenous equilibrium model. Both methodologies are compared in a shock tube and a throttle flow, which resembles the constrictions in Diesel injector passages. The mass transfer rate in the two phase model plays the fundamental role in affecting how close to equilibrium the model is; by increasing the mass transfer the two phase model comes close to the homogenous equilibrium model

Colour polymorphic Gouldian finches avoid complex backgrounds but prefer simple camouflage colours over white backgrounds

Many animals blend in well with their environment known as camouflage which is a successful predator avoidance strategy. However, captive environments often do not allow for camouflage and may result in stress and reduced welfare. We investigated whether colour polymorphic Gouldian finches use background matching or complex backgrounds as a camouflage strategy. Birds were tested in unfamiliar cages with half of the cage with one background and the other half with another background. The time spent in front of each background was measured. The first experiment compared a simple green background versus a complex patterned background consisting of red, green and black shapes, whereas the second experiment compared a simple green background against a white background which is often used in cages. Backgrounds were swapped after 10 days to control for site preferences (phase 1 and 2). In both experiments all birds clearly preferred the simple green background. Diverting habituation processes were observed in the second experiment with black-headed birds visiting the white background more during phase 1 than phase 2, whereas the opposite was the case for the red-headed birds. In the first experiment, preference for open habitats may have interfered with optimal background matching. The second experiment showed that white backgrounds are aversive for the birds. Different habituation speeds are consistent with differences in exploration and risk-taking between the head colour morphs. The results show that 2D background colours are a simple but effective enrichment to increase welfare in birds

Self-organized criticality in the hysteresis of the Sherrington - Kirkpatrick model

We study hysteretic phenomena in random ferromagnets. We argue that the angle dependent magnetostatic (dipolar) terms introduce frustration and long range interactions in these systems. This makes it plausible that the Sherrington - Kirkpatrick model may be able to capture some of the relevant physics of these systems. We use scaling arguments, replica calculations and large scale numerical simulations to characterize the hysteresis of the zero temperature SK model. By constructing the distribution functions of the avalanche sizes, magnetization jumps and local fields, we conclude that the system exhibits self-organized criticality everywhere on the hysteresis loop.Comment: 4 pages, 4 eps figure

Antiplatelet agents for chronic kidney disease

To evaluate the benefits and harms of antiplatelet therapy in patients with any form of kidney disease, including patients with CKD not receiving renal replacement therapy (RRT), patients receiving any form of dialysis, and kidney transplant recipients

Initiation of the SGLT2 inhibitor canagliflozin to prevent kidney and heart failure outcomes guided by HbA1c, albuminuria, and predicted risk of kidney failure

Background: Sodium glucose co-transporter-2 (SGLT2) inhibitors reduce the risk of kidney and heart failure events independent of glycemic effects. We assessed whether initiation of the SGLT2 inhibitor canagliflozin guided by multivariable predicted risk based on clinical characteristics and novel biomarkers is more efficient to prevent clinical outcomes compared to a strategy guided by HbA1c or urinary-albumin-creatinine ratio (UACR) alone. Methods: We performed a post-hoc analysis of the CANVAS trial including 3713 patients with available biomarker measurements. We compared the number of composite kidney (defined as a sustained 40% decline in eGFR, chronic dialysis, kidney transplantation, or kidney death) and composite heart failure outcomes (defined as heart failure hospitalization or cardiovascular (CV) death) prevented per 1000 patients treated for 5 years when canagliflozin was initiated in patients according to HbA1c ≥ 7.5%, UACR, or multivariable risk models consisting of: (1) clinical characteristics, or (2) clinical characteristics and novel biomarkers. Differences in the rates of events prevented between strategies were tested by Chi2-statistic. Results: After a median follow-up of 6.1 years, 144 kidney events were recorded. The final clinical model included age, previous history of CV disease, systolic blood pressure, UACR, hemoglobin, body weight, albumin, estimated glomerular filtration rate, and randomized treatment assignment. The combined biomarkers model included all clinical characteristics, tumor necrosis factor receptor-1, kidney injury molecule-1, matrix metallopeptidase-7 and interleukin-6. Treating all patients with HbA1c ≥ 7.5% (n = 2809) would prevent 33.0 (95% CI 18.8 to 43.3) kidney events at a rate of 9.6 (95% CI 5.5 to 12.6) events prevented per 1000 patients treated for 5 years. The corresponding rates were 5.8 (95% CI 3.4 to 7.9), 16.6 (95% CI 9.5 to 22.0) (P < 0.001 versus HbA1c or UACR approach), and 17.5 (95% CI 10.0 to 23.0) (P < 0.001 versus HbA1c or UACR approach; P = 0.54 versus clinical model). Findings were similar for the heart failure outcome. Conclusion: Initiation of canagliflozin based on an estimated risk-based approach prevented more kidney and heart failure outcomes compared to a strategy based on HbA1c or UACR alone. There was no apparent gain from adding novel biomarkers to the clinical risk model. These findings support the use of risk-based assessment using clinical markers to guide initiation of SGLT2 inhibitors in patients with type 2 diabetes

High sensitivity cardiac troponin T and N-terminal pro-BNP predict cardiovascular events and death in patients with type 2 diabetes mellitus

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