scholarly journals POLOS STABILITY EFFECT OF BLOCK DENSITY AND WAIST THICKNESS

1982 ◽  
Vol 1 (18) ◽  
pp. 121
Author(s):  
D.J.P. Scholtz ◽  
J.A. Zwamborn ◽  
M. Van Niekerk

Model tests were done with dolosse having the same shape and volume, but with different block densities, to determine the effect of block density on stability and to check whether the theoretical third-power relationship between block volume and relative block density is valid. From these tests it can be concluded that the higher the density of the block material the greater the stability becomes. Although the individual scatter is appreciable, the average results indicate that the stability of dolosse is inversely proportional to a power of about 2,3 of the relative density, which is significantly less than the theoretical power of 3. Model tests were also carried out on dolosse having the same mass and volume but with different waist-to-height ratios to determine the effect of waist-to-height ratio on the stability of a dolos armour. From the results of these tests it can be concluded that the stability of the armour decreases with increasing waist thickness, particularly for relatively high waist ratios.

1986 ◽  
Vol 1 (20) ◽  
pp. 157
Author(s):  
Hans Werner Pertenscky ◽  
John Rutte ◽  
Reinold Schmidt

As a result of the large-scale failure of the rubblemound breakwater at SINES, Portugal in 1978 a number of research programs were begun. At present, however, very little information is available from technical publications regarding new design criteria, recommendations, or test procedures for model tests of rubblemound breakwaters. The need still exists, therefore, for economically practical model tests and standardized test procedures so that more tests can be conducted and reproducible results from different institutions can be compared. At the same time, a number of factors related to the stability of rubblemound surface elements, and the interrelationships between those factors, have not been adequately examined or explained. Apparently without extensive model tests, for example, it has been suggested that greater stability can be obtained by using elements with greater unit weights (comparing elements of the same absolute weight) , either by adding scrap metal or denser materials, such as granite, to the concrete. Furthermore, susceptibility to breakage is of major importance to the long-term stability of armour layer units, particularly for dolos and similar less massive element types. This aspect has been generally neglected in laboratory tests, however, and attempts to simulate the lower ultimate strength of elements in reduced-scale model tests appear extremely difficult, as well as costly in terms of time and materials. Several other factors which can significantly affect the stability of an armour layer include the surface roughness of the individual elements, as well as boundary conditions such as the beach slope.


Methodology ◽  
2006 ◽  
Vol 2 (4) ◽  
pp. 142-148 ◽  
Author(s):  
Pere J. Ferrando

In the IRT person-fluctuation model, the individual trait levels fluctuate within a single test administration whereas the items have fixed locations. This article studies the relations between the person and item parameters of this model and two central properties of item and test scores: temporal stability and external validity. For temporal stability, formulas are derived for predicting and interpreting item response changes in a test-retest situation on the basis of the individual fluctuations. As for validity, formulas are derived for obtaining disattenuated estimates and for predicting changes in validity in groups with different levels of fluctuation. These latter formulas are related to previous research in the person-fit domain. The results obtained and the relations discussed are illustrated with an empirical example.


2020 ◽  
Vol 35 (2) ◽  
pp. 111-118
Author(s):  
Md Rizwanul Ahsan ◽  
Sabrina Makbul ◽  
Probir Kumar Sarkar

Background: Now a days unhealthy lifestyle primarily responsible for the dramatic increase obesity among children and adolescents. Objective: The purpose of the study is to see the effects of a multidisciplinary lifestyle intervention to reduce obese children and adolescents. The main outcome was cardiometabolic risk based on the waist-to-height ratio (WHTR) measurement. Secondary outcomes were (1) changes in body composition; (2) adherence to a Mediterranean diet; and (3) physical performance. Methods: The study involved 64 overweight/obese children or adolescents conducted at Dhaka Shishu Hospital from October 2017 to September 2018. The intervention was multidisciplinary including nutrition, exercise, and psychological aspects based on a family-based approach; it was delivered for six months for children and three months for adolescents. Before and after the intervention, several anthropometric measures height, body weight, body mass index (BMI), waist circumference, and body composition, cardiometabolic risk index waist-to-height ratio (WHTR), and dietary habits of the participants and their families were evaluated. In addition, a set of functional motor fitness tests was performed to evaluate physical performance measures. Results: After the intervention both children and adolescents showed a significant reduction in body weight, BMI, waist circumference, fat mass, and WHTR index and an improvement of fat-free mass, adherence to the Mediterranean diet, and physical fitness performance. Conclusion: A short term family-based multidisciplinary approach is effective in ameliorating the health status, dietary habits, and physical performance in children and adolescents. DS (Child) H J 2019; 35(2) : 111-118


Author(s):  
Luisa Lampignano ◽  
Roberta Zupo ◽  
Rossella Donghia ◽  
Vito Guerra ◽  
Fabio Castellana ◽  
...  

Background: There is moderate-to-high evidence that the Mediterranean diet prevents increases in body weight and waist circumference in non-obese individuals but less is known about its effects in subjects with overweight and obesity. The present study was focused on exploring the cross-sectional association among the adherence to Mediterranean diet and the most commonly used variables of metabolic and cardiovascular risk factors in a cohort of overweight subjects from a typical Mediterranean region, Apulia, in Southern Italy. Methods:: The study was performed in a cohort of 1214 individuals, all with overweight or obesity but no other clinical condition. We investigated the association among adherence to Mediterranean diet, assessed with the PREDIMED score, and anthropometric parameters [namely body mass index (BMI), WC, waist to height ratio (WHtR) and neck circumference (NC)], fasting serum levels of glucose, insulin, uric acid and lipids (triglycerides, total cholesterol, HDL cholesterol and LDL cholesterol), and blood pressure and insulin resistance, measured by HOMA-IR. Results:: The waist to height ratio was negatively associated to a PREDIMED score ≥7 (p<0.04), whereas HDL cholesterol was positively associated to a PREDIMED score ≥7 (p<0.04) Conclusion: This study suggests that body fat distribution and HDL-cholesterol are the parameters most strongly influenced by MedDiet in Apulian subjects.


Author(s):  
Sally Sonia Simmons ◽  
John Elvis Hagan ◽  
Thomas Schack

Hypertension is a major public health burden in Bangladesh. However, studies considering the underlying multifaceted risk factors of this health condition are sparse. The present study concurrently examines anthropometric parameters and intermediary factors influencing hypertension risk in Bangladesh. Using the 2018 World Health Organisation (WHO) STEPwise approach to non-communicable disease risk factor surveillance (STEPS) study conducted in Bangladesh and involving 8019 nationally representative adult respondents, bivariate and multivariate logistic regression analyses were performed to determine the association between anthropometrics, other intermediary factors and hypertension. The regression results were presented using the odds ratio (OR) and adjusted odds ratio (AOR) at 95% confidence intervals (CIs). The risk of hypertension was higher among females and males who were 40 years and older. However, among females, those who were age 60 years and older were more than twice and thrice more likely to be hypertensive compared to those in the younger age groups (18–39, 40–59). Females who were obese (body mass index [BMI], waist to hip ratio [WHR], waist to height ratio [WHtR]) or had high waist circumference [WC] were twice as likely to be hypertensive. Males and females who were physically active, consuming more fruits and vegetables daily and educated had lower odds of developing hypertension. Key findings suggest that the association between anthropometric indices (body mass index [BMI], waist to hip ratio [WHR], waist to height ratio [WHtR]), waist circumference [WC]), other intermediary determinants (e.g., education, physical activity) and hypertension exist across gender and with increasing age among adults in Bangladesh. Developing appropriate public health interventions (e.g., regular assessment of anthropometric parameters) for early identification of the risk and pattern of hypertension through appropriate screening and diagnosis is required to meet the specific health needs of the adult Bangladesh population.


2020 ◽  
Vol 26 (3) ◽  
pp. 223-244
Author(s):  
W. John Thrasher ◽  
Michael Mascagni

AbstractIt has been shown that when using a Monte Carlo algorithm to estimate the electrostatic free energy of a biomolecule in a solution, individual random walks can become entrapped in the geometry. We examine a proposed solution, using a sharp restart during the Walk-on-Subdomains step, in more detail. We show that the point at which this solution introduces significant bias is related to properties intrinsic to the molecule being examined. We also examine two potential methods of generating a sharp restart point and show that they both cause no significant bias in the examined molecules and increase the stability of the run times of the individual walks.


2019 ◽  
Vol 39 (2) ◽  
pp. 330-336 ◽  
Author(s):  
Jing Dong ◽  
Si-si Wang ◽  
Xi Chu ◽  
Jing Zhao ◽  
Ying-zhi Liang ◽  
...  

2020 ◽  
Vol 33 (8) ◽  
pp. 983-993 ◽  
Author(s):  
Muhammad Asif ◽  
Muhammad Aslam ◽  
Saima Altaf ◽  
Sajid Mustafa

AbstractObjectivesChildren from different countries and with different ethnic backgrounds have a distinct pattern of central fat deposition. Therefore, it is essential to develop population-specific percentiles of waist circumference (WC), waist-to-height ratio (WHtR) and waist-to-height ratio exponent (WHtR (exp)) for the evaluation of central obesity. The objective of this study was to develop age-and-gender-specific smoothed WC and WHtR percentile curves for the Pakistani children and adolescents aged 2–18 years.MethodsA cross-sectional data-set from a multi-ethnic anthropometric survey was considered. A sample of 10,668 healthy subjects (boys = 51.92%; and girls = 48.08%), aged 2–18 years was studied. Height (cm) and WC (cm) of each subject was measured under standard procedure and WHtR & WHtR (exp) were calculated. Age-and-gender-specific smoothed curves were obtained using the lambda-mu-sigma (LMS) method and compared with percentile curves obtained from different countries.ResultsExcept few early ages, the WC values increased with age in both sexes. Both boys and girls had approximately similar WC during 6–11 years of age and after age of 11, the boys had larger WC than the girls had. For WHtR, the centile curves showed a continuous decrease by 16 years of age and then increased gradually. WHtR of the girls in various ages were having similar or higher than those of the boys. In comparison of WC 50th and 90th percentiles with other countries, it was found that except few ages, the Pakistani children had larger WC than the other reference populations and the results of WHtR were also comparable to the other nations.ConclusionsWe present new reference data of WC, WHtR and WHtR (exp) using a representative sample of the Pakistani children aged 2–18 years. These reference values can be used provisionally for early detection of central obesity and its associated risks in the Pakistani children.


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