298 research outputs found
Combinatorial rigidity for some infinitely renormalizable unicritical polynomials
We prove combinatorial rigidity of infinitely renormalizable unicritical polynomials, P_c :z mapsto z^d+c, with complex c, under the a priori bounds and a certain combinatorial condition . This implies the local connectivity of the connectedness loci (the Mandelbrot set when d = 2) at the corresponding parameters
Investigating the relationship between low serum cholesterol and suicide in attempters with depression
Background & Objective: It has been postulated that depressed individuals with low total cholesterol levels may be more likely to die prematurely from suicide. This study aimed to examine the association between low serum cholesterol and suicide in depressed attempters. Materials & Methods: In this cross-sectional study, 180 suicide attempters, who met the inclusion criteria and were willing to participate in the study, were recruited in 2017. The data was collected using a demographic questionnaire and the Beck Depression Inventory-Second Edition (BDI-II). The blood cholesterol level was measured via an auto-analyzer. Results: The mean age was 26.39±10.75 years. The average cholesterol level in the moderate, severe, and serious depression groups was 151.30±35.23, 145.89±36.32, and 145.15±33.33, respectively. The mean age was higher in the group with a higher depression level, though the difference was not significant (P=0.06). The percentage of suicide attempts in single individuals was significantly higher (P=0.02). The mean cholesterol level in the group with the highest level of depression was the lowest, but the difference was insignificant (r=-.01, P=0.85). Only in females, the level of blood cholesterol showed a nearly significant difference between groups with different severities of depression (P=0.05). Cholesterol had a significant correlation with suicide frequency (P=0.008, r=0.28). Conclusion: Our results revealed no significant association between low serum cholesterol and suicide in attempters with depression; but low total serum cholesterol may be associated with depression and suicide in depressed subjects. Yet, more studies are required for verification of this causality. © 2020, Journal of Advances in Medical and Biomedical Research. All rights reserved
Analytic maps of parabolic and elliptic type with trivial centralisers
We prove that for a dense set of irrational numbers α, the analytic centraliser of the map e^{2πiα} z+ z2 near 0 is trivial. We also prove that some analytic circle diffeomorphisms in the Arnold family, with irrational rotation numbers, have trivial centralisers. These provide the first examples of such maps with trivial centralisers
Patient preferences and willingness-to-pay for a home or clinic based program of chronic heart failure management: findings from the which? trial
BACKGROUND Beyond examining their overall cost-effectiveness and mechanisms of effect, it is important to understand patient preferences for the delivery of different modes of chronic heart failure management programs (CHF-MPs). We elicited patient preferences around the characteristics and willingness-to-pay (WTP) for a clinic or home-based CHF-MP. METHODOLOGY/PRINCIPAL FINDINGS A Discrete Choice Experiment was completed by a sub-set of patients (n = 91) enrolled in the WHICH? trial comparing home versus clinic-based CHF-MP. Participants provided 5 choices between hypothetical clinic and home-based programs varying by frequency of nurse consultations, nurse continuity, patient costs, and availability of telephone or education support. Participants (aged 71±13 yrs, 72.5% male, 25.3% NYHA class III/IV) displayed two distinct preference classes. A latent class model of the choice data indicated 56% of participants preferred clinic delivery, access to group CHF education classes, and lower cost programs (p<0.05). The remainder preferred home-based CHF-MPs, monthly rather than weekly visits, and access to a phone advice service (p<0.05). Continuity of nurse contact was consistently important. No significant association was observed between program preference and participant allocation in the parent trial. WTP was estimated from the model and a dichotomous bidding technique. For those preferring clinic, estimated WTP was ≈AU15-105). CONCLUSIONS/SIGNIFICANCE Patient preferences for CHF-MPs were dichotomised between a home-based model which is more likely to suit older patients, those who live alone, and those with a lower household income; and a clinic-based model which is more likely to suit those who are more socially active and wealthier. To optimise the delivery of CHF-MPs, health care services should consider their patients’ preferences when designing CHF-MPs.Jennifer A. Whitty, Simon Stewart, Melinda J. Carrington, Alicia Calderone, Thomas Marwick, John D. Horowitz, Henry Krum, Patricia M. Davidson, Peter S. Macdonald, Christopher Reid, Paul A. Scuffha
Obesity and male breast cancer: Provocative parallels?
While rare compared to female breast cancer the incidence of male breast cancer (MBC) has increased in the last few decades. Without comprehensive epidemiological studies, the explanation for the increased incidence of MBC can only be speculated. Nevertheless, one of the most worrying global public health issues is the exponential rise in the number of overweight and obese people, especially in the developed world. Although obesity is not considered an established risk factor for MBC, studies have shown increased incidence among obese individuals. With this observation in mind, this article highlights the correlation between the increased incidence of MBC and the current trends in obesity as a growing problem in the 21st century, including how this may impact treatment. With MBC becoming more prominent we put forward the notion that, not only is obesity a risk factor for MBC, but that increasing obesity trends are a contributing factor to its increased incidence
Validation of the Framingham hypertension risk score in a middle eastern population: Tehran lipid and glucose study (TLGS)
Background The Framingham hypertension risk score is a well-known and simple model for predicting hypertension in adults. In the current study, we aimed to assess the predictive ability of this model in a Middle Eastern population.MethodsWe studied 5423 participants, aged 20-69years, without hypertension, who participated in two consecutive examination cycles of the Tehran Lipid and Glucose Study (TLGS). We assessed discrimination based on Harrell's concordance statistic (c-index) and calibration (graphical comparison of predicted vs. observed). We evaluated the original, recalibrated (for intercept and slope), and revised (for beta coefficients) models.ResultsOver the 3-year follow-up period, 319 participants developed hypertension. The Framingham hypertension risk score performed well in discriminating between individuals who developed hypertension and those who did not (c-index=0.81, 95% CI: 0.79-0.83). Initially, there was a systematic underestimation of the original risk score (events predicted), which was readily corrected by a simple model revision.ConclusionsThe revised Framingham hypertension risk score can be used as a screening tool in public health and clinical practice to facilitate the targeting of preventive interventions in high-risk Middle Eastern people.Development and application of statistical models for medical scientific researc
Dynamic temporary blood facility location-allocation during and post-disaster periods
The key objective of this study is to develop a tool (hybridization or integration of different techniques) for locating the temporary blood banks during and post-disaster conditions that could serve the hospitals with minimum response time. We have used temporary blood centers, which must be located in such a way that it is able to serve the demand of hospitals in nearby region within a shorter duration. We are locating the temporary blood centres for which we are minimizing the maximum distance with hospitals. We have used Tabu search heuristic method to calculate the optimal number of temporary blood centres considering cost components. In addition, we employ Bayesian belief network to prioritize the factors for locating the temporary blood facilities. Workability of our model and methodology is illustrated using a case study including blood centres and hospitals surrounding Jamshedpur city. Our results shows that at-least 6 temporary blood facilities are required to satisfy the demand of blood during and post-disaster periods in Jamshedpur. The results also show that that past disaster conditions, response time and convenience for access are the most important factors for locating the temporary blood facilities during and post-disaster periods
Transport time scales in soil erosion modelling
Unlike sediment transport in rivers, erosion of agricultural soil must overcome its cohesive strength to move soil particles into suspension. Soil particle size variability also leads to fall velocities covering many orders of magnitude, and hence to different suspended travel distances in overland flow. Consequently, there is a large range of inherent time scales involved in transport of eroded soil. For conditions where there is a constant rainfall rate and detachment is the dominant erosion mechanism, we use the Hairsine-Rose (HR) model to analyze these timescales, to determine their magnitude (bounds) and to provide simple approximations for them. We show that each particle size produces both fast and slow timescales. The fast timescale controls the rapid adjustment away from experimental initial conditions – this happens so quickly that it cannot be measured in practice. The slow time scales control the subsequent transition to steady state and are so large that true steady state is rarely achieved in laboratory experiments. Both the fastest and slowest time scales are governed by the largest particle size class. Physically, these correspond to the rate of vertical movement between suspension and the soil bed, and the time to achieve steady state, respectively. For typical distributions of size classes, we also find that there is often a single dominant time scale that governs the growth in the total mass of sediment in the non-cohesive deposited layer. This finding allows a considerable simplification of the HR model leading to analytical expressions for the evolution of suspended and deposited layer concentrations
Catchment drainage network scaling laws found experimentally in overland flow morphologies
The scaling relation between the drainage area and stream length (Hack's law), along with exceedance probabilities of drainage area, discharge, and upstream flow network length, is well known for channelized fluvial regions. We report here on a laboratory experiment on an eroding unconsolidated sediment for which no channeling occurred. Laser scanning was used to capture the morphological evolution of the sediment. High-intensity, spatially nonuniform rainfall ensured that the morphology changed substantially over the 16-hr experiment. Based on the surface scans and precipitation distribution, overland flow was estimated with the D8 algorithm, which outputs a flow network that was analyzed statistically. The above-mentioned scaling and exceedance probability relationships for this overland flow network are the same as those found for large-scale catchments and for laboratory experiments with observable channels. In addition, the scaling laws were temporally invariant, even though the network dynamically changed over the course of experiment
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