Micromethod for Estimation of the Degree of Crosslinking in Elastomers from Compression Modulus of Swollen Vulcanizates

1969 ◽  
Vol 42 (2) ◽  
pp. 580-588
Author(s):  
Derek A. Smith
Keyword(s):  
Compression Modulus ◽  
Active Network ◽  
Small Samples ◽  
Equilibrium Stress ◽  
Physically Active ◽  
Network Chain ◽  
Swelling Agent ◽  
Hydrocarbon Solvents ◽  
Swollen Vulcanizates ◽  
Better Than

Abstract The method uses small specimens (of volume less than 0.1 cc) which swell to diffusion equilibrium in hydrocarbon solvents within 8 hr. Measurements of deflection to better than one μ are made with a modified Wallace microhardness tester, which is described. The name “reticulometer” is proposed for this instrument. Using peroxide-crosslinked natural rubbers swollen to equilibrium νr values of about 0.23 in n-decane or in benzene, values for the concentration of physically active network chains determined by the present method were not greatly different from those determined by conventional “equilibrium” stress—strain measurements in tension on the same samples. Detailed differences are discussed. The chief advantages of the microcompression method are: (a) the use of small samples of shape and size convenient for carrying out other conventional measurements of network chain density; (b) the rapid attainment of diffusion equilibrium encouraging the use of fully swollen specimens and minimizing the risk of inhomogeneous distribution of swelling agent; and (c) the rapidity of testing compared with tension measurements.

The Application of Improved SVM in Mixed Circuit

2012 ◽  
Vol 224 ◽  
pp. 493-496 ◽  
Author(s):  
Huai Long Wang ◽  
Qiang Pan ◽  
Hong Liu
Keyword(s):  
Wavelet Transform ◽  
Fault Diagnosis ◽  
Small Samples ◽  
Lifting Wavelet Transform ◽  
Fault Features ◽  
Diagnosis Method ◽  
Lifting Wavelet ◽  
Current Characteristics ◽  
Mixed Circuit ◽  
Better Than

In order to improve the speed and the rate of fault diagnosis in mixed circuit, this paper introduces a new fault diagnosis method. Through extracting fault features of current characteristics effectively and applying to Improved SVM, the ability of pattern recognition will be better than the traditional BP Neural Network and Single SVM, especially in small samples or non-linear cases. Meanwhile, this paper presents the lifting wavelet transform in order to obtain the feature information accurately. The accuracy of fault diagnosis can greatly enhance by discussing the Improved SVM combined with lifting wavelet transform in a specific monostable trigger. That points out a new direction for the fault diagnosis of mixed circuit.

scholarly journals Quantitative spectrographic analysis of biological material. I-A method for the determination of lead in cerebrospinal fluid

1936 ◽  
Vol 120 (819) ◽  
pp. 380-380
Keyword(s):  
Cerebrospinal Fluid ◽  
Biological Material ◽  
Spectroscopic Method ◽  
Previous Treatment ◽  
Small Samples ◽  
Spectrographic Analysis ◽  
Better Than

A quantitative spectroscopic method of the determination of small concentrations of lead in certain biological material is described. It is valid for concentrations between 1 x 10 -8 and 2 x 10 -5 gm/cc, and the precision of a determination is better than 15%. The ability to make determinations with very small samples, and to use the material without previous treatment, are important features of the method.

The Relationship Between Postural Control and Self-Reported Engagement in Physical Activity in Young and Older Age

2016 ◽  
Vol 24 (2) ◽  
pp. 196-200 ◽  
Author(s):  
Bożena Wojciechowska-Maszkowska ◽  
Dorota Borzucka ◽  
Aleksandra Maria Rogowska ◽  
Michał Kuczyński
Keyword(s):  
Physical Activity ◽  
Postural Control ◽  
Force Plate ◽  
Physical And Mental Health ◽  
Physically Active ◽  
Beneficial Effects ◽  
Eyes Open ◽  
The Relationship ◽  
Postural Performance ◽  
Better Than

Physical activity is known to have beneficial effects on a host of factors related to physical and mental health, and positively affects postural control. However, there is no agreement on which measures of postural control and to what extent they are dependent on the past and present physical activity in older adults. To answer this question we compared the postural performance in a 20-s quiet stance with eyes open on a Kistler force plate in 38 subjects, aged 60–92, who were formerly and are currently physically active (AA) with those who were always inactive (II) and those who were either formerly (AI) or are currently (IA) active. Results indicated that only current activity promoted better postural control while former activity was ineffective. Postural control in AA and IA was very similar and much better than in II and AI who, in contrast, displayed similarly deteriorated postural control.

scholarly journals Comparison of Functional Fitness and Self-esteem among Elderly Women Engaging Different Exercise Programs: Walking, Low Impact Aerobic, and Chi-kung

2007 ◽  
Vol 13 (2) ◽  
pp. 49-55
Author(s):  
Gladys Shuk Fong LI ◽  
Hsiu Hua WANG ◽  
Chen Yu HUANG
Keyword(s):  
Elderly Women ◽  
The Elderly ◽  
Self Esteem ◽  
Measuring Instruments ◽  
Functional Fitness ◽  
Exercise Programs ◽  
Physically Active ◽  
The Mean ◽  
Chi Kung ◽  
Better Than

LANGUAGE NOTE | Document text in Chinese; abstract also in English. Purposes: 1) Elderly females engaging different exercise programs (walking, low impact aerobic, chi-kung) and sedentary elderly women were compared on self-esteem and functional fitness; 2) The predictability of the 6 functional fitness variables to self-esteem was also tested. Methods: 256 elderly females (55-75 years old) were selected from each of the 3-exercised group (walking, low-impact aerobic, and chi-kung class) and sedentary group respectively. Measuring instruments included Functional Fitness Test and Rosenberg Self-Esteem Scale (RSES). One-way ANOVA was utilized to compare the three exercised-group of subjects on the overall self-esteem score (Rosenberg, 1965), and the multiple regression analysis was utilized to determine whether the 6 functional fitness predictors add to a linear function of self-esteem. Results: ‘Flexibility' was found to be significant (p < .05) predictor of self-esteem. Self-esteem , ‘BMI', ‘FLEX', ‘BAL', and ‘AGIL' of the physically active elderly women were significantly (p<.05) better than the non-exercised women. Furthermore, Self-esteem , ‘BMI', ‘FLEX', ‘BAL', ‘MUSCU', and ‘AGIL' scores of the elderly women of low impact aerobic exercised-group was significantly higher than those of the walking and Chi-kung group. However, no significant differences (p>.05) were found among the three groups in the mean‘ CARDIO' scores. Conclusion: Elderly females engaging in low impact aerobic have higher self-esteem and better functional fitness. Furthermore, Flexibility is the most important predictor of self-esteem in elderly females. 目的：比較從事步行、低衝擊有氧、及氣功，與久坐生活形態之中老年婦女，其自尊值和功能性體適能之差異。同時評估六項功能性體適能指標對於自尊值的預測能力。方法：以256位自願參與，年齡介於55歲到77歲之中老年婦女為受測者，其中49位為久坐生活形態的中老年婦女，85位從事氣功；35位從事步行，以及87位從事低衝擊有氧運動。本研究之測量包括功能性體適能測驗以及羅斯伯格自尊心之測量。結果：一、功能性體適能中柔軟度為自尊程度的顯著(p<.05)預測用變項；二、從事規律運動的中老年婦女之自尊值、身體質量指數、柔軟度、平衡、及敏捷性顯著(p<.05)高於沒有從事規律運動的中老年婦女；三、從事低衝擊有氧運動之中老年婦女的自尊程度和功能性體適能顯著(p<.05)高於從事步行、氣功的中老年婦女。結論：從事低衝擊有氧運動的參與者有較高的自尊及較好的功能性體適能狀況。除此之外，柔軟度是「自尊」之重要預測用變項。

Magnetic properties of unrusted steel drums from laboratory and field‐magnetic measurements

Geophysics ◽  
1996 ◽  
Vol 61 (5) ◽  
pp. 1325-1335 ◽  
Author(s):  
Dhananjay Ravat
Keyword(s):  
Magnetic Properties ◽  
Magnetic Measurements ◽  
Magnetic Anomalies ◽  
Point Of View ◽  
Small Samples ◽  
Environmental Investigation ◽  
Bulk Magnetization ◽  
Steel Drums ◽  
Study Laboratory ◽  
Better Than

Laboratory‐derived magnetic properties from samples of steel drums appear to be lower than bulk magnetic properties required to produce observed magnetic anomalies over the same drums. The origin of this discrepancy is perhaps in the shape demagnetization experienced by samples used in the laboratory study. Laboratory observations of magnetic susceptibility in different directions suggest that the demagnetization mechanism may have significantly attenuated the laboratory‐derived magnetization values from small samples of drums. Field observations and computer modeling indicate that even though the effect of demagnetization is important for drum‐shaped objects, demagnetization is less pronounced in the shape of the drum than in the samples cut for laboratory measurements. Therefore, laboratory‐derived magnetizations from samples of steel drums cannot be used to model magnetic anomalies of steel drums. If laboratory‐derived magnetizations were used to model steel drums, the models would underestimate the resulting magnetic anomalies considerably and, in turn, would overestimate the number of buried drums at an environmental investigation site. Apparent bulk magnetization values for unrusted vertically oriented 55 and 30 gallon drums have been calculated (i.e., the values corrected for the effect of shape demagnetization of the drums). These range from ∼90 to ∼125 SI units (∼7 to ∼10 cgs units) for volume susceptibility and from ∼325 to ∼2750 A/m (∼0.325 to [Formula: see text]) for remanent magnetization (based on eight 55 gallon and four 30 gallon drums). Further deviations in these values could arise from the type and thickness of the steel and variations in manufacturing conditions affecting magnetizations. From the point of view of modeling the drums, at most source‐to‐observation distances applicable to environmental investigations, the equivalent source method is able to approximate the observed anomalies of steel drums better than the 3-D modeling method. With two years of rusting, magnetic anomalies of some of the drums have reduced, while in other drums, they have slightly increased. The overall magnetic changes caused by rusting appear to be more complex than anticipated, at least in the initial phase of rusting.

9. Physically active elderly women sleep more and better than sedentary women

2009 ◽  
Vol 120 (1) ◽  
pp. e3
Author(s):  
L.H.C.T. Guimaraes ◽  
L.B.C. Carvalho ◽  
G.F. Prado
Keyword(s):  
Elderly Women ◽  
Physically Active ◽  
Sedentary Women ◽  
Better Than

Determination of the Number of Common Stochastic Trends under Conditional Heteroskedasticity

2021 ◽  
Vol 28 (3) ◽  
pp. 519-552
Author(s):  
Giuseppe Cavaliere ◽  
Anders Rahbek ◽  
A. M. Robert Taylor
Keyword(s):  
Small Samples ◽  
Wild Bootstrap ◽  
Financial Variables ◽  
Finite Samples ◽  
Stochastic Trends ◽  
Sequential Procedures ◽  
Bootstrap Tests ◽  
The Business Cycle ◽  
Better Than

Permanent-transitory decompositions and the analysis of the time series properties of economic variables at the business cycle frequencies strongly rely on the correct detection of the number of common stochastic trends (co-integration). Standard techniques for the determination of the number of common trends, such as the well-known sequential procedure proposed in Johansen (1996), are based on the assumption that shocks are homoskedastic. This contrasts with empirical evidence which documents that many of the key macro-economic and financial variables are driven by heteroskedastic shocks. In a recent paper, Cavaliere et al., (2010, Econometric Theory) demonstrate that Johansen's (LR) trace statistic for co-integration rank and both its i.i.d. and wild bootstrap analogues are asymptotically valid in non-stationary systems driven by heteroskedastic (martingale difference) innovations, but that the wild bootstrap performs substantially better than the other two tests in finite samples. In this paper we analyse the behaviour of sequential procedures to determine the number of common stochastic trends present based on these tests. Numerical evidence suggests that the procedure based on the wild bootstrap tests performs best in small samples under a variety of heteroskedastic innovation processes.

Physically active elderly women sleep more and better than sedentary women

2008 ◽  
Vol 9 (5) ◽  
pp. 488-493 ◽  
Author(s):  
Laiz Helena de Castro Toledo Guimaraes ◽  
Luciane Bizari Coin de Carvalho ◽  
Gianni Yanaguibashi ◽  
Gilmar Fernandes do Prado
Keyword(s):  
Elderly Women ◽  
Physically Active ◽  
Sedentary Women ◽  
Better Than

Prevalence, Measurement, and Experience of Eating Disorders in Sport and Retirement

2018 ◽  
Author(s):  
Trent A. Petrie
Keyword(s):  
Eating Disorders ◽  
Diagnostic Criteria ◽  
Female Athletes ◽  
Self Report ◽  
Small Samples ◽  
Physically Active ◽  
Clinical Interviews ◽  
Not Otherwise Specified ◽  
Sport Type ◽  
Track Athletes

Although the specific prevalence rates may vary, eating disorders (ED) affect male and female athletes regardless of sport type and competitive level. Generally, rates of subclinical disorders are much higher than clinical ones, with the most frequent clinical classification being Eating Disorders Not Otherwise Specified. Further, EDs occur not only among active athletes, but are also found in samples of retired athletes as well. Existing research on the prevalence of EDs in athletes, however, has been limited due to its reliance on out-of-date diagnostic criteria, sometimes small samples, and a focus on point prevalence to the exclusion of examining how rates might change over time. Central to prevalence research and clinical assessments is the ability to accurately assess EDs in athletes. Although structured clinical interviews represent the most valid approach, they are time consuming and not often used in determining prevalence. Researchers have relied on self-report measures instead. Such measures include those developed initially in nonathletes, but used to study athletes (e.g., Questionnaire for Eating Disorder Diagnosis; Mintz, O’Halloran, Mulholland, & Schneider, 1997), and those specifically for athletes (e.g., Athletic Milieu Direct Questionnaire; Nagel, Black, Leverenz, & Coster, 2000). Most of these measures, though having adequate psychometric properties, are based on diagnostic criteria that are no longer in use, so additional research that employs prevalence measures that reflect DSM-5 criteria is needed with athletes. Most ED research in sport has used samples of active athletes; few studies have considered how the transition out of sport might affect athletes’ perceptions of their bodies, their relationship to food, and their approaches to exercise and being physically active. Retirement from sport generally is considered to be a developmental stressor and thus may exacerbate ED symptoms and body image concerns in some athletes. Yet, for other athletes, retirement may represent a positive transition in which they emerge from a sport culture, focused on weight and appearance, to reclaim themselves and their bodies. Initial qualitative findings appear to support each hypothesis in part, though longitudinal quantitative studies that track athletes from active competition through retirement are needed to understand the changes athletes experience in relation to their bodies, food, and exercise, and when such changes are most likely to occur.

scholarly journals Rasch Versus Classical Equating in the Context of Small Sample Sizes

2019 ◽  
Vol 80 (3) ◽  
pp. 499-521
Author(s):  
Ben Babcock ◽  
Kari J. Hodge
Keyword(s):  
Item Difficulty ◽  
Real Data ◽  
Past Research ◽  
Small Sample ◽  
Small Samples ◽  
Sample Sizes ◽  
Certification Exam ◽  
Small Sample Sizes ◽  
The Rasch Model ◽  
Better Than

Equating and scaling in the context of small sample exams, such as credentialing exams for highly specialized professions, has received increased attention in recent research. Investigators have proposed a variety of both classical and Rasch-based approaches to the problem. This study attempts to extend past research by (1) directly comparing classical and Rasch techniques of equating exam scores when sample sizes are small ( N≤ 100 per exam form) and (2) attempting to pool multiple forms’ worth of data to improve estimation in the Rasch framework. We simulated multiple years of a small-sample exam program by resampling from a larger certification exam program’s real data. Results showed that combining multiple administrations’ worth of data via the Rasch model can lead to more accurate equating compared to classical methods designed to work well in small samples. WINSTEPS-based Rasch methods that used multiple exam forms’ data worked better than Bayesian Markov Chain Monte Carlo methods, as the prior distribution used to estimate the item difficulty parameters biased predicted scores when there were difficulty differences between exam forms.

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