A Thermodamage Strength Theoretical Model of Ceramic Materials Taking into Account the Effect of Residual Stress

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Weiguo Li

2012-01-01

Full Text Available A thermodamage strength theoretical model taking into account the effect of residual stress was established and applied to each temperature phase based on the study of effects of various physical mechanisms on the fracture strength of ultrahigh-temperature ceramics. The effects of SiC particle size, crack size, and SiC particle volume fraction on strength corresponding to different temperatures were studied in detail. This study showed that when flaw size is not large, the bigger SiC particle size results in the greater effect of tensile residual stress in the matrix grains on strength reduction, and this prediction coincides with experimental results; and the residual stress and the combined effort of particle size and crack size play important roles in controlling material strength.

Importance of Tensile Strength on the Shear Behavior of Discontinuities

Science.gov (United States)

Ghazvinian, A. H.; Azinfar, M. J.; Geranmayeh Vaneghi, R.

2012-05-01

In this study, the shear behavior of discontinuities possessing two different rock wall types with distinct separate compressive strengths was investigated. The designed profiles consisted of regular artificial joints molded by five types of plaster mortars, each representing a distinct uniaxial compressive strength. The compressive strengths of plaster specimens ranged from 5.9 to 19.5 MPa. These specimens were molded considering a regular triangular asperity profile and were designed so as to achieve joint walls with different strength material combinations. The results showed that the shear behavior of discontinuities possessing different joint wall compressive strengths (DDJCS) tested under constant normal load (CNL) conditions is the same as those possessing identical joint wall strengths, but the shear strength of DDJCS is governed by minor joint wall compressive strength. In addition, it was measured that the predicted values obtained by Barton's empirical criterion are greater than the experimental results. The finding indicates that there is a correlation between the joint roughness coefficient (JRC), normal stress, and mechanical strength. It was observed that the mode of failure of asperities is either pure tensile, pure shear, or a combination of both. Therefore, Barton's strength criterion, which considers the compressive strength of joint walls, was modified by substituting the compressive strength with the tensile strength. The validity of the modified criterion was examined by the comparison of the predicted shear values with the laboratory shear test results reported by Grasselli (Ph.D. thesis n.2404, Civil Engineering Department, EPFL, Lausanne, Switzerland, 2001). These comparisons infer that the modified criterion can predict the shear strength of joints more precisely.

PARANOID INDIVIDUALS WITH SCHIZOPHRENIA SHOW GREATER SOCIAL COGNITIVE BIAS AND WORSE SOCIAL FUNCTIONING THAN NON-PARANOID INDIVIDUALS WITH SCHIZOPHRENIA.

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Pinkham, Amy E; Harvey, Philip D; Penn, David L

2016-03-01

Paranoia is a common symptom of schizophrenia that may be related to how individuals process and respond to social stimuli. Previous investigations support a link between increased paranoia and greater social cognitive impairments, but these studies have been limited to single domains of social cognition, and no studies have examined how paranoia may influence functional outcome. Data from 147 individuals with schizophrenia were used to examine whether actively paranoid and non-paranoid individuals with schizophrenia differ in social cognition and functional outcomes. On measures assessing social cognitive bias, paranoid individuals endorsed more hostile and blaming attributions and identified more faces as untrustworthy; however, paranoid and non-paranoid individuals did not differ on emotion recognition and theory of mind tasks assessing social cognitive ability. Likewise, paranoid individuals showed greater impairments in real-world interpersonal relationships and social acceptability as compared to non-paranoid patients, but these differences did not extend to performance based tasks assessing functional capacity and social competence. These findings isolate specific social cognitive disparities between paranoid and non-paranoid subgroups and suggest that paranoia may exacerbate the social dysfunction that is commonly experienced by individuals with schizophrenia.

Leg strength and lean mass symmetry influences kicking performance in Australian football.

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Hart, Nicolas H; Nimphius, Sophia; Spiteri, Tania; Newton, Robert U

2014-01-01

Differential loading patterns during game-based participation may produce or exacerbate strength imbalances between the lower limbs. It is currently unknown whether such imbalances are functionally beneficial or detrimental to performance. This study assessed the influence of lower limb strength and lean mass symmetry on kicking accuracy in Australian Football. Thirty-one Australian footballers were required to perform a kicking assessment, producing ten drop punt kicks over twenty metres to a player target. Athletes were subsequently separated into accurate (n = 15) and inaccurate (n = 16) groups, with lower-body lean mass assessed using whole body DXA scans, and lower-body strength assessed using an isometric protocol. Accurate kickers demonstrated significantly higher relative lean mass (~8% to 16%; p = 0. 001 to 0.004) and significantly lower relative fat mass (~21% to 40%; p = 0.001 to 0.024) than inaccurate kickers. Accurate kickers did not contain any significant difference in lean mass or unilateral strength between lower limbs. Inaccurate kickers displayed significant asymmetry in lean mass (~3%; p ≤ 0.003), producing significant imbalances in strength (~8%; p ≤ 0.002) highlighting a deficiency in their support leg. Greater relative strength and improved lower limb symmetry in strength and muscularity could increase the capacity of an athlete to be technically proficient in favour of greater accuracy. Key PointsStrength deficits in the support leg may lead to inaccurate kicking outcomes.An asymmetry of 3% in lean mass generated an 8% imbalance in leg strength.Greater levels of relative lower-body strength and muscle mass are associated with improved kicking accuracy performance.

Properties analysis of tensile strength, crystallinity degree and microstructure of polymer composite polypropylene-sand

International Nuclear Information System (INIS)

Sudirman; Karo-Karo, Aloma; Ari-Handayani; Bambang-Sugeng; Rukihati; Mashuri

2004-01-01

Materials modification base on polymer toward polymer composite is needed by addition of filler. Mechanical properties such as tensile strength, crystallinity degree and microstructure of polymer composite based on polypropylene with sand filler have been investigated. In this work, the polymer composite has been made by mixing the matrix of polypropylene melt flow 2 (PP MF2) or polypropylene melt flow 10 (PP MF 10) with sand filler in a labo plastomill. The composition of sand filler was varied to 10, 30, 40 and 50 % v/v, a then the composite were casted to the film sheets form. The sheets were characterized mechanically i.e tensile strength, crystallinity degree and microstructure. The result showed that the tensile strength decreased by increasing the volume fraction of sand filler, in accordance with microstructure investigation that the matrix area under zone plastic deformation (more cracks), while the filler experienced elastic deformation, so that the strength mechanism of filler did not achieved with expectation (Danusso and Tieghi theory). For filler more than 30 % of volume fraction, the tensile strength of polypropylene melt flow 10 (PP MF 10) was greater than that polypropylene melt flow 2 (PP MF2). It was caused by plasticities in PP MF 10. The tensile strength of PP MF2 was greater than that PP MF 10 for volume fraction of sand filler less than 30 %. It was caused by PP MF2 to be have more degree of crystallinity

Effect of Protein Intake on Strength, Body Composition and Endocrine Changes in Strength/Power Athletes

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Kang Jie

2006-12-01

Full Text Available Abstract Comparison of protein intakes on strength, body composition and hormonal changes were examined in 23 experienced collegiate strength/power athletes participating in a 12-week resistance training program. Subjects were stratified into three groups depending upon their daily consumption of protein; below recommended levels (BL; 1.0 – 1.4 g·kg-1·day-1; n = 8, recommended levels (RL; 1.6 – 1.8 g·kg-1·day-1; n = 7 and above recommended levels (AL; > 2.0 g·kg-1·day-1; n = 8. Subjects were assessed for strength [one-repetition maximum (1-RM bench press and squat] and body composition. Resting blood samples were analyzed for total testosterone, cortisol, growth hormone, and insulin-like growth factor. No differences were seen in energy intake (3,171 ± 577 kcal between the groups, and the energy intake for all groups were also below the recommended levels for strength/power athletes. No significant changes were seen in body mass, lean body mass or fat mass in any group. Significant improvements in 1-RM bench press and 1-RM squat were seen in all three groups, however no differences between the groups were observed. Subjects in AL experienced a 22% and 42% greater change in Δ 1-RM squat and Δ 1-RM bench press than subjects in RL, however these differences were not significant. No significant changes were seen in any of the resting hormonal concentrations. The results of this study do not provide support for protein intakes greater than recommended levels in collegiate strength/power athletes for body composition improvements, or alterations in resting hormonal concentrations.

Pelvic floor muscle strength in primiparous women according to the delivery type: cross-sectional study

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Edilaine de Paula Batista Mendes

Full Text Available ABSTRACT Objectives: to compare the pelvic floor muscle strength in primiparous women after normal birth and cesarean section, related to the socio-demographic characteristics, nutritional status, dyspareunia, urinary incontinence, perineal exercise in pregnancy, perineal condition and weight of the newborn. Methods: this was a cross-sectional study conducted after 50 - 70 postpartum days, with 24 primiparous women who underwent cesarean delivery and 72 who had a normal birth. The 9301 PeritronTM was used for analysis of muscle strength. The mean muscle strength was compared between the groups by two-way analysis of variance. Results: the pelvic floor muscle strength was 24.0 cmH2O (±16.2 and 25.4 cmH2O (±14.7 in postpartum primiparous women after normal birth and cesarean section, respectively, with no significant difference. The muscular strength was greater in postpartum women with ≥ 12 years of study (42.0 ±26.3 versus 14.6 ±7.7 cmH2O; p= 0.036 and in those who performed perineal exercises (42.6±25.4 11.8±4.9 vs. cmH2O; p = 0.010, compared to caesarean. There was no difference in muscle strength according to delivery type regarding nutritional status, dyspareunia, urinary incontinence, perineal condition or newborn weight. Conclusion: pelvic floor muscle strength does not differ between primiparous women based on the type of delivery. Postpartum women with normal births, with higher education who performed perineal exercise during pregnancy showed greater muscle strength.

Interfacial Shear Strength and Adhesive Behavior of Silk Ionomer Surfaces.

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Kim, Sunghan; Geryak, Ren D; Zhang, Shuaidi; Ma, Ruilong; Calabrese, Rossella; Kaplan, David L; Tsukruk, Vladimir V

2017-09-11

The interfacial shear strength between different layers in multilayered structures of layer-by-layer (LbL) microcapsules is a crucial mechanical property to ensure their robustness. In this work, we investigated the interfacial shear strength of modified silk fibroin ionomers utilized in LbL shells, an ionic-cationic pair with complementary ionic pairing, (SF)-poly-l-glutamic acid (Glu) and SF-poly-l-lysine (Lys), and a complementary pair with partially screened Coulombic interactions due to the presence of poly(ethylene glycol) (PEG) segments and SF-Glu/SF-Lys[PEG] pair. Shearing and adhesive behavior between these silk ionomer surfaces in the swollen state were probed at different spatial scales and pressure ranges by using functionalized atomic force microscopy (AFM) tips as well as functionalized colloidal probes. The results show that both approaches were consistent in analyzing the interfacial shear strength of LbL silk ionomers at different spatial scales from a nanoscale to a fraction of a micron. Surprisingly, the interfacial shear strength between SF-Glu and SF-Lys[PEG] pair with partially screened ionic pairing was greater than the interfacial shear strength of the SF-Glu and SF-Lys pair with a high density of complementary ionic groups. The difference in interfacial shear strength and adhesive strength is suggested to be predominantly facilitated by the interlayer hydrogen bonding of complementary amino acids and overlap of highly swollen PEG segments.

Does bipolar electrocoagulation time affect vessel weld strength?

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Harrison, J D; Morris, D L

1991-01-01

The value of the bipolar electrocoagulator in the haemostasis of bleeding ulcers is controversial. We have therefore investigated the effect of different coagulation times on vessel weld strength achieved by the bipolar device. Welds were then made in vessels of known diameter using a standard 10F endoscopic haemostatic probe at coagulation times of two and 20 seconds. The intravascular temperature achieved at each time was measured. Vessel weld strength achieved by bipolar electrocoagulation was much greater at 20 seconds (approximately twice that at two seconds) and was highly significantly greater at all vessel diameters. There was a gradual reduction in weld strength with increasing vessel diameter, an effect that was seen for both two and 20 seconds of electrocoagulation. Intravascular temperature was significantly higher at 20 seconds than at two seconds. We conclude that vessel weld strength is related to coagulation time and that any future studies comparing the bipolar electrocoagulator with other haemostatic devices should use longer periods of bipolar electrocoagulation and record the coagulation time in order to optimise the clinical value of the device. PMID:1864540

Creep Strength of Discontinuous Fibre Composites

DEFF Research Database (Denmark)

Pedersen, Ole Bøcker

1974-01-01

relation between stress and strain rate. Expressions for the interface stress, the creep velocity profile adjacent to the fibres and the creep strength of the composite are derived. Previous results for the creep strength, sc = aVfs0 ( \\frac[( Î )\\dot] [( Î )\\dot] 0 )1/nr1 + 1/n c=Vf001n1+1n in which[( Î...... )\\dot] is the composite creep rate,V f is the fibre volume fraction,sgr 0,epsi 0 andn are the constants in the matrix creep law. The creep strength coefficient agr is found to be very weakly dependent onV f and practically independent ofn whenn is greater than about 6....

The strength of polyaxial locking interfaces of distal radius plates.

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Hoffmeier, Konrad L; Hofmann, Gunther O; Mückley, Thomas

2009-10-01

Currently available polyaxial locking plates represent the consequent enhancement of fixed-angle, first-generation locking plates. In contrast to fixed-angle locking plates which are sufficiently investigated, the strength of the new polyaxial locking options has not yet been evaluated biomechanically. This study investigates the mechanical strength of single polyaxial interfaces of different volar radius plates. Single screw-plate interfaces of the implants Palmar 2.7 (Königsee Implantate und Instrumente zur Osteosynthese GmbH, Allendorf, Germany), VariAx (Stryker Leibinger GmbH & Co. KG, Freiburg, Germany) und Viper (Integra LifeSciences Corporation, Plainsboro, NJ, USA) were tested by cantilever bending. The strength of 0 degrees, 10 degrees and 20 degrees screw locking angle was obtained during static and dynamic loading. The Palmar 2.7 interfaces showed greater ultimate strength and fatigue strength than the interfaces of the other implants. The strength of the VariAx interfaces was about 60% of Palmar 2.7 in both, static and dynamic loading. No dynamic testing was applied to the Viper plate because of its low ultimate strength. By static loading, an increase in screw locking angle caused a reduction of strength for the Palmar 2.7 and Viper locking interfaces. No influence was observed for the VariAx locking interfaces. During dynamic loading; angulation had no influence on the locking strength of Palmar 2.7. However, reduction of locking strength with increasing screw angulation was observed for VariAx. The strength of the polyaxial locking interfaces differs remarkably between the examined implants. Depending on the implant an increase of the screw locking angle causes a reduction of ultimate or fatigue strength, but not in all cases a significant impact was observed.

HORMONE REPLACEMENT AND STRENGTH TRAINING POSITIVELY INFLUENCE BALANCE DURING GAIT IN POST-MENOPAUSAL FEMALES: A PILOT STUDY

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Stephen D. Perry

2005-12-01

Full Text Available This study examined the effects of hormone replacement combined with strength training on improving dynamic balance control in post-menopausal women. Thirty one participating post-menopausal women were divided into three groups (hormone replacement (HR, non-hormone replacement (NR and control (CR group. HR and NR groups were tested for muscle strength and balance control during gait, prior to training and following a six week lower body strength training program. Quadriceps muscle strength was evaluated as isokinetic peak torque (60°·sec-1 using a CYBEX NORM and balance control was evaluated by center of mass - base of support relationships and ground reaction forces during gait perturbations. Only the HR group showed significantly (p < 0.05 improved balance control during the initial phase of unexpected gait termination and single stance periods while walking across uneven terrain following training. The strength gains in the HR group tended to be greater than in the NR group over the six week training program, although neither group showed statistically significant increases. The CR group showed no significant differences between testing times. HR in post-menopausal females may enhance dynamic balance control when combined with a strength training program, even if no statistically significant gains in strength are achieved

Tensile strength/yield strength (TS/YS) ratios of high-strength steel (HSS) reinforcing bars

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Tavio, Anggraini, Retno; Raka, I. Gede Putu; Agustiar

2018-05-01

The building codes such as American Concrete Institute (ACI) 318M-14 and Standard National Indonesia (SNI) 2847:2013 require that the ratio of tensile strength (TS) and yield strength (YS) should not less than 1.25. The requirement is based on the assumption that a capability of a structural member to develop inelastic rotation capacity is a function of the length of the yield region. This paper reports an investigation on various steel grades, namely Grades 420, 550, 650, and 700 MPa, to examine the impact of different TS/YS ratios if it is less or greater than the required value. Grades 550, 650, and 700 MPa were purposely selected with the intention to examine if these higher grades are still promising to be implemented in special structural systems since they are prohibited by the building codes for longitudinal reinforcement, whereas Grade 420 MPa bars are the maximum limit of yield strength of reinforcing bars that is allowable for longitudinal reinforcement of special structural systems. Tensile tests of these steel samples were conducted under displacement controlled mode to capture the complete stress-strain curves and particularly the post-yield response of the steel bars. From the study, it can be concluded that Grade 420 performed higher TS/YS ratios and they were able to reach up to more than 1.25. However, the High Strength Still (HSS) bars (Grades 550, 600, and 700 MPa) resulted in lower TS/YS ratios (less than 1.25) compared with those of Grade 420 MPa.

The relationship between compressive strength and flexural strength of pavement geopolymer grouting material

Science.gov (United States)

Zhang, L.; Han, X. X.; Ge, J.; Wang, C. H.

2018-01-01

To determine the relationship between compressive strength and flexural strength of pavement geopolymer grouting material, 20 groups of geopolymer grouting materials were prepared, the compressive strength and flexural strength were determined by mechanical properties test. On the basis of excluding the abnormal values through boxplot, the results show that, the compressive strength test results were normal, but there were two mild outliers in 7days flexural strength test. The compressive strength and flexural strength were linearly fitted by SPSS, six regression models were obtained by linear fitting of compressive strength and flexural strength. The linear relationship between compressive strength and flexural strength can be better expressed by the cubic curve model, and the correlation coefficient was 0.842.

American State Gun Law Strength and State Resident Differences in Neuroticism Levels

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Stewart J. H. McCann

2016-04-01

Full Text Available Relations between state gun law strength and state-aggregated levels of Republican leaning, gun ownership, and resident Big Five neuroticism (based on 619,397 residents nationally were determined in a state-level analysis of the 50 American states using multiple regression strategies with state socioeconomic status, white population percent, and urban population percent statistically controlled. In a standard hierarchical model with state gun law strength as the criterion, the three demographic variables accounted for 44.4% of the variance and the Big Five accounted for another 21.9%. When the Big Five entered stepwise after the demographics, neuroticism was the sole significant personality predictor, accounting for another 13.4% of the variance. Greater state gun law strength was associated with higher state resident neuroticism. Further hierarchical regression analyses showed that state Republican leaning and gun ownership could account separately and jointly for significant variance in state gun law strength but not with state resident neuroticism controlled.

Influence of ultraviolet irradiation treatment on porcelain bond strength of titanium surfaces.

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Kumasaka, Tomonari; Ohno, Akinori; Hori, Norio; Hoshi, Noriyuki; Maruo, Katsuichiro; Kuwabara, Atsushi; Seimiya, Kazuhide; Toyoda, Minoru; Kimoto, Katsuhiko

2018-01-26

To determine the effect of titanium (Ti) surface modification by ultraviolet irradiation (UVI) on the bond strength between Ti and porcelain. Grade 2 Ti plates were allotted to five groups: sandblasted (SA), 15 min UVI (UV), SA+5 min UVI (SA+UV5), SA+10 min UVI (SA+UV10), and SA+15 min UVI (SA+UV15). After surface treatment, porcelain was added. A precious metal (MC) was used for comparison with Ti. The effects of 24-h storage at room temperature versus thermal cycling only at 5 and 55°C in water were evaluated. Subsequently, the tensile strength of each sample was tested. Data were analyzed using one-way analysis of variance and the Tukey test. In both the room temperature and thermal cycling groups, the MC and SA+15 min UVI samples showed significantly greater bond strengths than the other samples (pbond strength between porcelain and the Ti surface.

Strengths only or strengths and relative weaknesses? A preliminary study.

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Rust, Teri; Diessner, Rhett; Reade, Lindsay

2009-10-01

Does working on developing character strengths and relative character weaknesses cause lower life satisfaction than working on developing character strengths only? The present study provides a preliminary answer. After 76 college students completed the Values in Action Inventory of Strengths (C. Peterson & M. E. P. Seligman, 2004), the authors randomly assigned them to work on 2 character strengths or on 1 character strength and 1 relative weakness. Combined, these groups showed significant gains on the Satisfaction With Life Scale (E. Diener, R. A. Emmons, R. J. Larsen, & S. Griffin, 1985), compared with a 32-student no-treatment group. However, there was no significant difference in gain scores between the 2-strengths group and the 1-character-strength-and-1-relative-character-weakness group. The authors discuss how focusing on relative character weaknesses (along with strengths) does not diminish-and may assist in increasing-life satisfaction.

Metallurgical/Alloy Optimization of High Strength and Wear Resistant Structural Quench and Tempered Steels

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Stalheim, Douglas G.; Peimao, Fu; Linhao, Gu; Yongqing, Zhang

Structural steels with yield strength requirements greater or equal to 690 MPa can be produced through controlled recrystallization hot rolling coupled with precipitation strengthening or purposeful heat treatment through quench and tempering (Q&T). High strength structural steel and wear/abrasion resistant requirements greater or equal to 360 Brinell hardness (BHN) are produced by the development of microstructures of tempered lower bainite and/or martensite through the Q&T process. While these Q&T microstructures can produce very high strengths and hardness levels making them ideal for 690 MPa plus yield strength or wear/abrasion resistant applications, they lack toughness/ductility and hence are very brittle and prone to cracking. While tempering the microstructures helps in improving the toughness/ductility and reducing the brittleness, strength and hardness can be sacrificed. In addition, these steels typically consist of alloy designs containing boron with carbon equivalents (CE) greater than 0.50 to achieve the desired microstructures. The higher CE has a negative influence on weldability.

Compressive and flexural strength of high strength phase change mortar

Science.gov (United States)

Qiao, Qingyao; Fang, Changle

2018-04-01

High-strength cement produces a lot of hydration heat when hydrated, it will usually lead to thermal cracks. Phase change materials (PCM) are very potential thermal storage materials. Utilize PCM can help reduce the hydration heat. Research shows that apply suitable amount of PCM has a significant effect on improving the compressive strength of cement mortar, and can also improve the flexural strength to some extent.

Isometric and swallowing tongue strength in healthy adults.

Science.gov (United States)

Todd, J Tee; Lintzenich, Catherine Rees; Butler, Susan G

2013-10-01

The tongue contributes to a safe swallow. It facilitates bolus control during mastication, maintains a bolus in the oral cavity to prevent premature entry of the bolus into the hypopharynx, and helps generate pressure in the hypopharynx during swallowing. This study examined isometric tongue strength and tongue pressure measured during swallowing in healthy young and older adults. Prospective group design. One hundred twenty-six healthy individuals who were recruited as part of a larger study on swallowing participated in this study. Participants were divided into three age groups: 20 to 40 years, 41 to 60 years, and ≥61 years. A KayPentax Digital Swallowing Workstation with an air-filled bulb array was placed on the tongue of each participant (anterior to posterior). Participants completed three isometric tongue presses and three swallows. Repeated measures analyses of variance revealed a significant main effect of age (P = .01) and gender by tongue bulb location interaction (P = .02) for isometric tongue strength. That is, older adults had lower isometric tongue strength than young adults, and females had a greater difference between anterior and posterior tongue strength than males. Tongue strength during swallowing yielded significantly greater anterior versus posterior tongue pressure. This study comprises one of the largest in terms of number of healthy participants reported to date and confirms previous findings that isometric tongue strength decreases with age. Furthermore, given young and older adults generate similar swallowing pressures, swallowing is a submaximal strength activity, yet older adults have less functional reserve. 4. Copyright © 2013 The American Laryngological, Rhinological, and Otological Society, Inc.

The contribution of prenatal environment and genetic factors to the association between birth weight and adult grip strength.

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Charlotte L Ridgway

2011-03-01

Full Text Available Low birth weight has been associated with reduced hand grip strength, which is a marker of future physical function and disease risk. The aim of this study was to apply a twin pair approach, using both 'individual' data and 'within-pair' differences, to investigate the influence of birth weight on hand grip strength and whether this association may be mediated through fat free mass (FFM. Participants from the East Flanders Prospective Twin Survey were included if born without congenital abnormalities, birth weight >500 g and ≥22 weeks of gestation. Follow up in adulthood (age: 18-34 year, included anthropometric measures and hand grip (n = 783 individuals, n = 326 same-sex twin pairs. Birth weight was positively associated with hand grip strength (β = 2.60 kg, 95% CI 1.52, 3.67, p<0.001 and FFM (β = 4.2, 95% CI 3.16, 5.24, p<0.001, adjusted for gestational age, sex and adult age. Using 'within-pair' analyses, the birth weight hand grip association was significant in DZ men only (β = 5.82, 95% CI 0.67, 10.97, p = 0.028, which was attenuated following adjustment for FFM. Within-pair birth weight FFM associations were most pronounced in DZ men (β = 11.20, 95% CI 7.18, 15.22, p<0.001. Our 'individual' analyses show that higher birth weight is associated with greater adult hand grip strength, which is mediated through greater adult FFM. The 'within-pair' analyses confirm this observation and furthermore show that, particularly in men, genetic factors may in part explain this association, as birth weight differences in DZ men result in greater differences in adult strength and FFM.

Adaptations in athletic performance after ballistic power versus strength training.

Science.gov (United States)

Cormie, Prue; McGuigan, Michael R; Newton, Robert U

2010-08-01

To determine whether the magnitude of improvement in athletic performance and the mechanisms driving these adaptations differ in relatively weak individuals exposed to either ballistic power training or heavy strength training. Relatively weak men (n = 24) who could perform the back squat with proficient technique were randomized into three groups: strength training (n = 8; ST), power training (n = 8; PT), or control (n = 8). Training involved three sessions per week for 10 wk in which subjects performed back squats with 75%-90% of one-repetition maximum (1RM; ST) or maximal-effort jump squats with 0%-30% 1RM (PT). Jump and sprint performances were assessed as well as measures of the force-velocity relationship, jumping mechanics, muscle architecture, and neural drive. Both experimental groups showed significant (P training with no significant between-group differences evident in either jump (peak power: ST = 17.7% +/- 9.3%, PT = 17.6% +/- 4.5%) or sprint performance (40-m sprint: ST = 2.2% +/- 1.9%, PT = 3.6% +/- 2.3%). ST also displayed a significant increase in maximal strength that was significantly greater than the PT group (squat 1RM: ST = 31.2% +/- 11.3%, PT = 4.5% +/- 7.1%). The mechanisms driving these improvements included significant (P force-velocity relationship, jump mechanics, muscle architecture, and neural activation that showed a degree of specificity to the different training stimuli. Improvements in athletic performance were similar in relatively weak individuals exposed to either ballistic power training or heavy strength training for 10 wk. These performance improvements were mediated through neuromuscular adaptations specific to the training stimulus. The ability of strength training to render similar short-term improvements in athletic performance as ballistic power training, coupled with the potential long-term benefits of improved maximal strength, makes strength training a more effective training modality for relatively weak individuals.

Creep Behavior of High-Strength Concrete Subjected to Elevated Temperatures.

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Yoon, Minho; Kim, Gyuyong; Kim, Youngsun; Lee, Taegyu; Choe, Gyeongcheol; Hwang, Euichul; Nam, Jeongsoo

2017-07-11

Strain is generated in concrete subjected to elevated temperatures owing to the influence of factors such as thermal expansion and design load. Such strains resulting from elevated temperatures and load can significantly influence the stability of a structure during and after a fire. In addition, the lower the water-to-binder (W-B) ratio and the smaller the quantity of aggregates in high-strength concrete, the more likely it is for unstable strain to occur. Hence, in this study, the compressive strength, elastic modulus, and creep behavior were evaluated at target temperatures of 100, 200, 300, 500, and 800 °C for high-strength concretes with W-B ratios of 30%, 26%, and 23%. The loading conditions were set as non-loading and 0.33f cu . It was found that as the compressive strength of the concrete increased, the mechanical characteristics deteriorated and transient creep increased. Furthermore, when the point at which creep strain occurred at elevated temperatures after the occurrence of transient creep was considered, greater shrinkage strain occurred as the compressive strength of the concrete increased. At a heating temperature of 800 °C, the 80 and 100 MPa test specimens showed creep failure within a shrinkage strain range similar to the strain at the maximum load.

Creep Behavior of High-Strength Concrete Subjected to Elevated Temperatures

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Minho Yoon

2017-07-01

Full Text Available Strain is generated in concrete subjected to elevated temperatures owing to the influence of factors such as thermal expansion and design load. Such strains resulting from elevated temperatures and load can significantly influence the stability of a structure during and after a fire. In addition, the lower the water-to-binder (W–B ratio and the smaller the quantity of aggregates in high-strength concrete, the more likely it is for unstable strain to occur. Hence, in this study, the compressive strength, elastic modulus, and creep behavior were evaluated at target temperatures of 100, 200, 300, 500, and 800 °C for high-strength concretes with W–B ratios of 30%, 26%, and 23%. The loading conditions were set as non-loading and 0.33fcu. It was found that as the compressive strength of the concrete increased, the mechanical characteristics deteriorated and transient creep increased. Furthermore, when the point at which creep strain occurred at elevated temperatures after the occurrence of transient creep was considered, greater shrinkage strain occurred as the compressive strength of the concrete increased. At a heating temperature of 800 °C, the 80 and 100 MPa test specimens showed creep failure within a shrinkage strain range similar to the strain at the maximum load.

Repair Strength in Simulated Restorations of Methacrylate- or Silorane-Based Composite Resins.

Science.gov (United States)

Consani, Rafael Leonardo Xediek; Marinho, Tatiane; Bacchi, Atais; Caldas, Ricardo Armini; Feitosa, Victor Pinheiro; Pfeifer, Carmem Silvia

2016-01-01

The study verified the bond strength in simulated dental restorations of silorane- or methacrylate-based composites repaired with methacrylate-based composite. Methacrylate- (P60) or silorane-based (P90) composites were used associated with adhesive (Adper Single Bond 2). Twenty-four hemi-hourglass-shaped samples were repaired with each composite (n=12). Samples were divided according to groups: G1= P60 + Adper Single Bond 2+ P60; G2= P60 + Adper Single Bond 2 + P60 + thermocycling; G3= P90 + Adper Single Bond 2 + P60; and G4= P90 + Adper Single Bond 2 + P60 + thermocycling. G1 and G3 were submitted to tensile test 24 h after repair procedure, and G2 and G4 after submitted to 5,000 thermocycles at 5 and 55 ?#61616;C for 30 s in each bath. Tensile bond strength test was accomplished in an universal testing machine at crosshead speed of 0.5 mm/min. Data (MPa) were analyzed by two-way ANOVA and Tukey's test (5%). Sample failure pattern (adhesive, cohesive in resin or mixed) was evaluated by stereomicroscope at 30?#61655; and images were obtained in SEM. Bond strength values of methacrylate-based composite samples repaired with methacrylate-based composite (G1 and G2) were greater than for silorane-based samples (G3 and G4). Thermocycling decreased the bond strength values for both composites. All groups showed predominance of adhesive failures and no cohesive failure in composite resin was observed. In conclusion, higher bond strength values were observed in methacrylate-based resin samples and greater percentage of adhesive failures in silorane-based resin samples, both composites repaired with methacrylate-based resin.

Comparing strengths of beliefs explicitly

NARCIS (Netherlands)

Ghosh, S.; de Jongh, D.

2013-01-01

Inspired by a similar use in provability logic, formulas p > B q and p ≥ B q are introduced in the existing logical framework for discussing beliefs to express that the strength of belief in p is greater than (or equal to) that in q. Besides its usefulness in studying the properties of the concept

Effect of Resistance Training Frequency on Gains in Muscular Strength: A Systematic Review and Meta-Analysis.

Science.gov (United States)

Grgic, Jozo; Schoenfeld, Brad J; Davies, Timothy B; Lazinica, Bruno; Krieger, James W; Pedisic, Zeljko

2018-05-01

Current recommendations on resistance training (RT) frequency for gains in muscular strength are based on extrapolations from limited evidence on the topic, and thus their practical applicability remains questionable. To elucidate this issue, we conducted a systematic review and meta-analysis of the studies that compared muscular strength outcomes with different RT frequencies. To carry out this review, English-language literature searches of the PubMed/MEDLINE, Scopus, and SPORTDiscus databases were conducted. The meta-analysis was performed using a random-effects model. The meta-analysis models were generated with RT frequencies classified as a categorical variable as either 1, 2, 3, or 4+ times/week, or, if there were insufficient data in subgroup analyses, the training frequencies were categorized as 1, 2, or 3 times/week. Subgroup analyses were performed for potential moderators, including (1) training volume; (2) exercise selection for the 1 repetition maximum (RM) test (for both multi-joint and single-joint exercises); (3) upper and lower body strength gains; (4) training to muscular failure (for studies involving and not involving training to muscular failure); (5) age (for both middle-aged/older adults and young adults); and (6) sex (for men and for women). The methodological quality of studies was appraised using the modified Downs and Black checklist. A total of 22 studies were found to meet the inclusion criteria. The average score on the Downs and Black checklist was 18 (range 13-22 points). Four studies were classified as being of good methodological quality, while the rest were classified as being of moderate methodological quality. Results of the meta-analysis showed a significant effect (p = 0.003) of RT frequency on muscular strength gains. Effect sizes increased in magnitude from 0.74, 0.82, 0.93, and 1.08 for training 1, 2, 3, and 4+ times per week, respectively. A subgroup analysis of volume-equated studies showed no significant effect (p

The influence of cooling forearm/hand and gender on estimation of handgrip strength.

Science.gov (United States)

Cheng, Chih-Chan; Shih, Yuh-Chuan; Tsai, Yue-Jin; Chi, Chia-Fen

2014-01-01

Handgrip strength is essential in manual operations and activities of daily life, but the influence of forearm/hand skin temperature on estimation of handgrip strength is not well documented. Therefore, the present study intended to investigate the effect of local cooling of the forearm/hand on estimation of handgrip strength at various target force levels (TFLs, in percentage of MVC) for both genders. A cold pressor test was used to lower and maintain the hand skin temperature at 14°C for comparison with the uncooled condition. A total of 10 male and 10 female participants were recruited. The results indicated that females had greater absolute estimation deviations. In addition, both genders had greater absolute deviations in the middle range of TFLs. Cooling caused an underestimation of grip strength. Furthermore, a power function is recommended for establishing the relationship between actual and estimated handgrip force. Statement of relevance: Manipulation with grip strength is essential in daily life and the workplace, so it is important to understand the influence of lowering the forearm/hand skin temperature on grip-strength estimation. Females and the middle range of TFL had greater deviations. Cooling the forearm/hand tended to cause underestimation, and a power function is recommended for establishing the relationship between actual and estimated handgrip force. Practitioner Summary: It is important to understand the effect of lowering the forearm/hand skin temperature on grip-strength estimation. A cold pressor was used to cool the hand. The cooling caused underestimation, and a power function is recommended for establishing the relationship between actual and estimated handgrip force. Manipulation with grip strength is essential in daily life and the workplace, so it is important to understand the influence of lowering the forearm/hand skin temperature on grip-strength estimation. Females and the middle range of TFL had greater deviations. Cooling the

Male Astronauts Have Greater Bone Loss and Risk of Hip Fracture Following Long Duration Spaceflights than Females

Science.gov (United States)

Ellman, Rachel; Sibonga, Jean; Bouxsein, Mary

2010-01-01

This slide presentation reviews bone loss in males and compares it to female bone loss during long duration spaceflight. The study indicates that males suffer greater bone loss than females and have a greater risk of hip fracture. Two possible reason for the greater male bone loss are that the pre-menopausal females have the estrogen protection and the greater strength of men max out the exercise equipment that provide a limited resistance to 135 kg.

Practicing the Test Produces Strength Equivalent to Higher Volume Training.

Science.gov (United States)

Mattocks, Kevin T; Buckner, Samuel L; Jessee, Matthew B; Dankel, Scott J; Mouser, J Grant; Loenneke, Jeremy P

2017-09-01

To determine if muscle growth is important for increasing muscle strength or if changes in strength can be entirely explained from practicing the strength test. Thirty-eight untrained individuals performed knee extension and chest press exercise for 8 wk. Individuals were randomly assigned to either a high-volume training group (HYPER) or a group just performing the one repetition maximum (1RM) strength test (TEST). The HYPER group performed four sets to volitional failure (~8RM-12RM), whereas the TEST group performed up to five attempts to lift as much weight as possible one time each visit. Data are presented as mean (90% confidence interval). The change in muscle size was greater in the HYPER group for both the upper and lower bodies at most but not all sites. The change in 1RM strength for both the upper body (difference of -1.1 [-4.8, 2.4] kg) and lower body (difference of 1.0 [-0.7, 2.8] kg for dominant leg) was not different between groups (similar for nondominant). Changes in isometric and isokinetic torque were not different between groups. The HYPER group observed a greater change in muscular endurance (difference of 2 [1,4] repetitions) only in the dominant leg. There were no differences in the change between groups in upper body endurance. There were between-group differences for exercise volume (mean [95% confidence interval]) of the dominant (difference of 11,049.3 [9254.6-12,844.0] kg) leg (similar for nondominant) and chest press with the HYPER group completing significantly more total volume (difference of 13259.9 [9632.0-16,887.8] kg). These findings suggest that neither exercise volume nor the change in muscle size from training contributed to greater strength gains compared with just practicing the test.

Grip Strength and Its Relationship to Police Recruit Task Performance and Injury Risk: A Retrospective Cohort Study.

Science.gov (United States)

Orr, Robin; Pope, Rodney; Stierli, Michael; Hinton, Benjamin

2017-08-21

Suitable grip strength is a police occupational requirement. The aim of this study was to investigate the association between grip strength, task performance and injury risk in a police population. Retrospective data of police recruits (n = 169) who had undergone basic recruit training were provided, including handgrip strength results, occupational task performance measures (consisting of police task simulations [SIM], tactical options [TACOPS] and marksmanship assessments) and injury records. Left hand grip strength (41.91 ± 8.29 kg) measures showed a stronger correlation than right hand grip strength (42.15 ± 8.53 kg) with all outcome measures. Recruits whose grip strength scores were lower were significantly more susceptible to failing the TACOPS occupational task assessment than those with greater grip strength scores, with significant ( p ≤ 0.003) weak to moderate, positive correlations found between grip strength and TACOPS performance. A significant ( p performance, with those performing better in marksmanship having higher grip strength. Left hand grip strength was significantly associated with injury risk ( r = -0.181, p = 0.018) but right hand grip strength was not. A positive association exists between handgrip strength and police recruit task performance (notably TACOPS and marksmanship) with recruits who scored poorly on grip strength being at greatest risk of occupational assessment task failure.

Hormone Replacement and Strength Training Positively Influence Balance During Gait in Post-Menopausal Females: A Pilot Study

Science.gov (United States)

Perry, Stephen D.; Bombardier, Eric; Radtke, Alison; Tiidus, Peter M.

2005-01-01

This study examined the effects of hormone replacement combined with strength training on improving dynamic balance control in post-menopausal women. Thirty one participating post-menopausal women were divided into three groups (hormone replacement (HR), non-hormone replacement (NR) and control (CR) group). HR and NR groups were tested for muscle strength and balance control during gait, prior to training and following a six week lower body strength training program. Quadriceps muscle strength was evaluated as isokinetic peak torque (60°·sec-1) using a CYBEX NORM and balance control was evaluated by center of mass - base of support relationships and ground reaction forces during gait perturbations. Only the HR group showed significantly (p < 0.05) improved balance control during the initial phase of unexpected gait termination and single stance periods while walking across uneven terrain following training. The strength gains in the HR group tended to be greater than in the NR group over the six week training program, although neither group showed statistically significant increases. The CR group showed no significant differences between testing times. HR in post-menopausal females may enhance dynamic balance control when combined with a strength training program, even if no statistically significant gains in strength are achieved. Key Points This study provides evidence that even a short modest strength training program can enhance dynamic balance control in older adult females taking hormone replacement. If potential benefits of hormone replacement therapy extend to enhancing muscle strength then this would be important in designing optimal interventions for both strength and balance for this cohort. Future work should explore the influence of hormone replacement therapy on other dynamic balance or functional tasks. PMID:24501551

Reconnaissance map showing thickness of volcanic ash deposits in the greater Hilo area, Hawaii

Science.gov (United States)

Buchanan-Banks, Jane M.

1983-01-01

This study was undertaken to determine the thickness and distribution of volcanic ash deposits in the greater Hilo area, Hawaii, as a step toward evaluating their susceptibility to failure during earthquake shaking. On several occasions their instability has resulted in serious damage. For example, the 1868 earthquake (m=7+), following a prolonged rainy period, caused a debris flow of hillside ash deposits that killed 31 people in Wood Valley (Bringham, 1869). The 1973 Honomu earthquake (m=6.2) resulted in more damage from shaking to areas underlain by ash deposits in the older part of Hilo than in other areas, and soil slips in ash, as well as rockfalls, were common along the roads north of town (Nielsen and others, 1977). 

Computation of radionuclide particulate finite area fugitive source strengths

Energy Technology Data Exchange (ETDEWEB)

Fields, D E

1983-06-01

Atmospheric source strengths quantifying particulate re-suspension from wind and non-wind disturbance-driven processes are computed for sites of small area. These values are useful in computing downwind air concentration values to evaluate risk to exposed populations. The net source strength for the site is the sum of the wind- and disturbance-driven components. A unified source strength approach includes both classes of re-suspension processes. More research is needed to satisfactorily express the time-dependence of re-suspension parameters, especially in non-arid climates where population densities are greater. (JMT)

Sex matters: females in proestrus show greater diazepam anxiolysis and brain-derived neurotrophin factor- and parvalbumin-positive neurons than males.

Science.gov (United States)

Ravenelle, Rebecca; Berman, Ariel K; La, Jeffrey; Mason, Briana; Asumadu, Evans; Yelleswarapu, Chandra; Donaldson, S Tiffany

2018-04-01

In humans and animal models, sex differences are reported for anxiety-like behavior and response to anxiogenic stimuli. In the current work, we studied anxiety-like behavior and response to the prototypical anti-anxiety drug, diazepam. We used 6th generation outbred lines of adult Long Evans rats with high and low anxiety-like behavior phenotypes to investigate the impact of proestrus on the baseline and diazepam-induced behavior. At three doses of diazepam (0, 0.1, and 1.0 mg/kg, i.p.), we measured anxiogenic responses on the elevated plus maze of adult male and female rats. We assessed parvalbumin and brain-derived neurotrophin protein levels in forebrain and limbic structures implicated in anxiety/stress using immunohistochemistry. At baseline, we saw significant differences between anxiety lines, with high anxiety lines displaying less time on the open arms of the elevated plus maze, and less open arm entries, regardless of sex. During proestrus, high anxiety females showed less anxiety-like behavior at 0.1 mg/kg, while low anxiety females displayed less anxiety-like behavior at 0.1 and 1.0 doses, relative to males. Brain-derived neurotrophin protein was elevated in females in the medial prefrontal cortex and central amygdala, while parvalbumin-immunoreactive cells were greater in males in the medial prefrontal cortex. Parvalbumin-positive cells in high anxiety females were higher in CA2 and dentate gyrus relative to males from the same line. In sum, when tested in proestrus, females showed greater anxiolytic effects of diazepam relative to males, and this correlated with increases in neurotrophin and parvalbumin neuron density in corticolimbic structures. © 2018 Federation of European Neuroscience Societies and John Wiley & Sons Ltd.

Gender Differences in Isokinetic Strength after 60 and 90 d Bed Rest

Science.gov (United States)

English, K. L.; Ploutz-Snyder, R. J.; Cromwell, R. L.; Ploutz-Snyder, L. L.

2010-01-01

Recent reports suggest that changes in muscle strength following disuse may differ between males and females. PURPOSE: To examine potential gender differences in strength changes following 60 and 90 d of experimental bed rest. METHODS: Isokinetic extensor and flexor strength of the knee (60deg and 180deg/s, concentric only), ankle (30deg/s, concentric and eccentric), and trunk (60deg/s, concentric only) were measured following 60 d (males: n=4, 34.5+/-9.6 y; females: n=4, 35.5+/-8.2 y) and 90 d (males: n=10, 31.4+/-4.8 y; females: n=5, 37.6+/-9.9 y) of 6-degree head-down-tilt bed rest (BR; N=23). Subjects were fed a controlled diet (55%/15%/ 30%, CHO/PRO/FAT) that maintained body weight within 3% of the weight recorded on Day 3 of bed rest. After a familiarization session, testing was conducted 6 d before BR and 2 d after BR completion. Peak torque and total work were calculated for the tests performed. To allow us to combine data from both 60- and 90-d subjects, we used a mixed-model statistical analysis in which time and gender were fixed effects and bed rest duration was a random effect. Log-transformations of strength measures were utilized when necessary in order to meet statistical assumptions. RESULTS: Main effects were seen for both time and gender (p<0.05), showing decreased strength in response to bed rest for both males and females, and males stronger than females for most strength measures. Only one interaction effect was observed: females exhibited a greater loss of trunk extensor peak torque at 60 d versus pre-BR, relative to males (p=0.004). CONCLUSION: Sixty and 90 d of BR induced significant losses in isokinetic muscle strength of the locomotor and postural muscles of the knee, ankle, and trunk. Although males were stronger than females for most of the strength measures that we examined, only changes in trunk extensor peak torque were greater for females than males at day 60 of bed rest

Acute Effects of Partial-Body Cryotherapy on Isometric Strength: Maximum Handgrip Strength Evaluation.

Science.gov (United States)

De Nardi, Massimo; Pizzigalli, Luisa; Benis, Roberto; Caffaro, Federica; Micheletti Cremasco, Margherita

2017-12-01

De Nardi, M, Pizzigalli, L, Benis, R, Caffaro, F, and Cremasco, MM. Acute effects of partial-body cryotherapy on isometric strength: maximum handgrip strength evaluation. J Strength Cond Res 31(12): 3497-3502, 2017-The aim of the study was to evaluate the influence of a single partial-body cryotherapy (PBC) session on the maximum handgrip strength (JAMAR Hydraulic Hand dynamometer). Two hundred healthy adults were randomized into a PBC group and a control group (50 men and 50 women in each group). After the initial handgrip strength test (T0), the experimental group performed a 150-second session of PBC (temperature range between -130 and -160° C), whereas the control group stayed in a thermo neutral room (22.0 ± 0.5° C). Immediately after, both groups performed another handgrip strength test (T1). Data underlined that both groups showed an increase in handgrip strength values, especially the experimental group (Control: T0 = 39.48 kg, T1 = 40.01 kg; PBC: T0 = 39.61 kg, T1 = 41.34 kg). The analysis also reported a statistical effect related to gender (F = 491.99, P ≤ 0.05), with women showing lower handgrip strength values compared with men (women = 30.43 kg, men = 52.27 kg). Findings provide the first evidence that a single session of PBC leads to the improvement of muscle strength in healthy people. The results of the study imply that PBC could be performed also before a training session or a sport competition, to increase hand isometric strength.

Family Dynamics and Personal Strengths among Dementia Caregivers in Argentina

Science.gov (United States)

Elnasseh, Aaliah G.; Trujillo, Michael A.; Peralta, Silvina Victoria; Stolfi, Miriam E.; Morelli, Eliana; Perrin, Paul B.

2016-01-01

This study examined whether healthier family dynamics were associated with higher personal strengths of resilience, sense of coherence, and optimism among dementia caregivers in Argentina. Caregivers are usually required to assist individuals with dementia, and family members have typically fulfilled that role. Personal strengths such as resilience, sense of coherence, and optimism have been shown to protect caregivers from some of the negative experiences of providing care, though the family-related variables associated with these personal strengths are largely unknown. Hierarchical multiple regressions investigated the extent to which family dynamics variables are associated with each of the caregiver personal strengths after controlling for demographic and caregiver characteristics. A sample of 105 caregivers from Argentina completed a set of questionnaires during a neurologist visit. Family dynamics explained 32% of the variance in resilience and 39% of the variance in sense of coherence. Greater family empathy and decreased family problems were uniquely associated with higher resilience. Greater communication and decreased family problems were uniquely associated with higher sense of coherence. Optimism was not found to be significantly associated with family dynamics. These results suggest that caregiver intervention research focused on the family may help improve caregiver personal strengths in Argentina and other Latin American countries. PMID:27413574

Family Dynamics and Personal Strengths among Dementia Caregivers in Argentina

Directory of Open Access Journals (Sweden)

Aaliah G. Elnasseh

2016-01-01

Full Text Available This study examined whether healthier family dynamics were associated with higher personal strengths of resilience, sense of coherence, and optimism among dementia caregivers in Argentina. Caregivers are usually required to assist individuals with dementia, and family members have typically fulfilled that role. Personal strengths such as resilience, sense of coherence, and optimism have been shown to protect caregivers from some of the negative experiences of providing care, though the family-related variables associated with these personal strengths are largely unknown. Hierarchical multiple regressions investigated the extent to which family dynamics variables are associated with each of the caregiver personal strengths after controlling for demographic and caregiver characteristics. A sample of 105 caregivers from Argentina completed a set of questionnaires during a neurologist visit. Family dynamics explained 32% of the variance in resilience and 39% of the variance in sense of coherence. Greater family empathy and decreased family problems were uniquely associated with higher resilience. Greater communication and decreased family problems were uniquely associated with higher sense of coherence. Optimism was not found to be significantly associated with family dynamics. These results suggest that caregiver intervention research focused on the family may help improve caregiver personal strengths in Argentina and other Latin American countries.

Differential Effects of Heavy Versus Moderate Loads on Measures of Strength and Hypertrophy in Resistance-Trained Men.

Science.gov (United States)

Schoenfeld, Brad J; Contreras, Bret; Vigotsky, Andrew D; Peterson, Mark

2016-12-01

The purpose of the present study was to evaluate muscular adaptations between heavy- and moderate-load resistance training (RT) with all other variables controlled between conditions. Nineteen resistance-trained men were randomly assigned to either a strength-type RT routine (HEAVY) that trained in a loading range of 2-4 repetitions per set (n = 10) or a hypertrophy-type RT routine (MODERATE) that trained in a loading range of 8-12 repetitions per set (n = 9). Training was carried out 3 days a week for 8 weeks. Both groups performed 3 sets of 7 exercises for the major muscle groups of the upper and lower body. Subjects were tested pre- and post-study for: 1 repetition maximum (RM) strength in the bench press and squat, upper body muscle endurance, and muscle thickness of the elbow flexors, elbow extensors, and lateral thigh. Results showed statistically greater increases in 1RM squat strength favoring HEAVY compared to MODERATE. Alternatively, statistically greater increases in lateral thigh muscle thickness were noted for MODERATE versus HEAVY. These findings indicate that heavy load training is superior for maximal strength goals while moderate load training is more suited to hypertrophy-related goals when an equal number of sets are performed between conditions.

Differential Effects of Heavy Versus Moderate Loads on Measures of Strength and Hypertrophy in Resistance-Trained Men

Directory of Open Access Journals (Sweden)

Brad J. Schoenfeld, Bret Contreras, Andrew D. Vigotsky, Mark Peterson

2016-12-01

Full Text Available The purpose of the present study was to evaluate muscular adaptations between heavy- and moderate-load resistance training (RT with all other variables controlled between conditions. Nineteen resistance-trained men were randomly assigned to either a strength-type RT routine (HEAVY that trained in a loading range of 2-4 repetitions per set (n = 10 or a hypertrophy-type RT routine (MODERATE that trained in a loading range of 8-12 repetitions per set (n = 9. Training was carried out 3 days a week for 8 weeks. Both groups performed 3 sets of 7 exercises for the major muscle groups of the upper and lower body. Subjects were tested pre- and post-study for: 1 repetition maximum (RM strength in the bench press and squat, upper body muscle endurance, and muscle thickness of the elbow flexors, elbow extensors, and lateral thigh. Results showed statistically greater increases in 1RM squat strength favoring HEAVY compared to MODERATE. Alternatively, statistically greater increases in lateral thigh muscle thickness were noted for MODERATE versus HEAVY. These findings indicate that heavy load training is superior for maximal strength goals while moderate load training is more suited to hypertrophy-related goals when an equal number of sets are performed between conditions.

Pullout strength of misplaced pedicle screws in the thoracic and lumbar vertebrae - A cadaveric study

Directory of Open Access Journals (Sweden)

Shyam K Saraf

2013-01-01

Full Text Available Background: The objective of this cadaveric study was to analyze the effects of iatrogenic pedicle perforations from screw misplacement on the mean pullout strength of lower thoracic and lumbar pedicle screws. We also investigated the effect of bone mineral density (BMD, diameter of pedicle screws, and the region of spine on the pullout strength of pedicle screws. Materials and Methods: Sixty fresh human cadaveric vertebrae (D10-L2 were harvested. Dual-energy X-ray absorptiometry (DEXA scan of vertebrae was done for BMD. Titanium pedicle screws of different diameters (5.2 and 6.2 mm were inserted in the thoracic and lumbar segments after dividing the specimens into three groups: a standard pedicle screw (no cortical perforation; b screw with medial cortical perforation; and c screw with lateral cortical perforation. Finally, pullout load of pedicle screws was recorded using INSTRON Universal Testing Machine. Results: Compared with standard placement, medially misplaced screws had 9.4% greater mean pullout strength and laterally misplaced screws had 47.3% lesser mean pullout strength. The pullout strength of the 6.2 mm pedicle screws was 33% greater than that of the 5.2 mm pedicle screws. The pullout load of pedicle screws in lumbar vertebra was 13.9% greater than that in the thoracic vertebra ( P = 0.105, but it was not statistically significant. There was no significant difference between pullout loads of vertebra with different BMD ( P = 0.901. Conclusion: The mean pullout strength was less with lateral misplaced pedicle screws while medial misplaced pedicle screw had more pullout strength. The pullout load of 6.2 mm screws was greater than that of 5.2 mm pedicle screws. No significant correlation was found between bone mineral densities and the pullout strength of vertebra. Similarly, the pullout load of screw placed in thoracic and lumbar vertebrae was not significantly different.

Upper extremity injuries associated with strength training.

Science.gov (United States)

Haupt, H A

2001-07-01

Most injuries sustained during strength training are mild strains that resolve with appropriate rest. More severe injuries include traumatic shoulder dislocations, tendon ruptures of the pectoralis major, biceps, and triceps; stress fractures of the distal clavicle, humerus, radius, and ulna; traumatic fractures of the distal radius and ulna in adolescent weightlifters; and compressive and stretch neuropathies. These more severe injuries are usually the result of improperly performing a strength training exercise. Educating athletes regarding proper strength-training techniques serves to reverse established injury patterns and to prevent these injuries in the first place. Recognizing the association of anabolic steroid use to several of the injury patterns further reinforces the need for medical specialists to counsel athletes against their use. With the increasing use of supplements such as creatine, the incidence and nature of strength-training injuries may change further. Greater emphasis on the competitive performance of younger athletes undoubtedly will generate enthusiasm for strength training at earlier ages in both sexes. The importance of proper supervision of these young athletes by knowledgeable persons will increase. As the popularity of strength training grows, there will be ample opportunity to continue to catalog the injury patterns associated with this activity.

Enhanced shear strength of sodium bentonite using frictional additives

International Nuclear Information System (INIS)

Schmitt, K.E.; Bowders, J.J.; Gilbert, R.B.; Daniel, D.E.

1997-01-01

One of the most important obstacles to using geosynthetic clay liners (GCLs) in landfill cover systems is the low shear strength provided by the bentonitic portion of the GCL. In this study, the authors propose that granular, frictional materials might be added to the bentonite to form an admixture that would have greater shear strength than the bentonite alone while still raining low hydraulic conductivity. Bentonite was mixed with two separate granular additives, expanded shale and recycled to form mixtures consisting of 20-70% bentonite by weight. In direct shear tests at normal stresses of 34.5-103.5 kPa, effective friction angles were measured as 45 degrees for the expanded 36 degrees for the recycled glass, and 7 degrees for the hydrated granular bentonite. The strength of the expanded shale mixtures increased nearly linearly as the percentage shale in the mixture increased, to 44 degrees for a bentonite mixture with 80% shale. The addition of recycled glass showed little effect on the shear strength of the mixtures of glass and bentonite. Hydraulic conductivity measurements for both types of mixtures indicated a linear increase with log(k) as the amount of granular additive increased. For applications involving geosynthetic clay liners for cover systems, a mixture of 40% expanded shale and 60% bentonite is recommended, although further testing must be done. The 40/60 mixture satisfies the hydraulic equivalency requirement, with k = 5.1X10 -9 cm/sec, while increasing the shear strength parameters of the bentonitic mixture to φ' = 17 degrees and c' = 0

INFLUENCE OF STRENGTH TRAINING PROGRAM ON ISOMETRIC MUSCLE STRENGTH IN YOUNG ATHLETES

Directory of Open Access Journals (Sweden)

Dragan Radovanovic

2007-10-01

Full Text Available Strength training, or resistance training, is a form of physical conditioning used to increase the ability to resist force. Since muscular strength is required for success in many sports, it is logical to assume that stronger and more powerful young athletes will achieve better results. The aim of the study was to examine the effects of strength training on young athletes. An eight-week strength training program for developing muscle strength was performed in this study. Training protocol was designed specifically for young adolescent’s athletes. The program consisted of exercises for lower and upper body, abdominal and lower back muscles. The programs did not involve the maximal (1-3 repetitions maximum and other very hard intensity exercises that may had negative effect on young athletes. The results showed that strength training program had positive effects on maximal isometric muscle force (Fmax and motor skill. The increase presents the combined influence of strength training and growth.

Strength, body composition, and functional outcomes in the squat versus leg press exercises.

Science.gov (United States)

Rossi, Fabrício E; Schoenfeld, Brad J; Ocetnik, Skyler; Young, Jonathan; Vigotsky, Andrew; Contreras, Bret; Krieger, James W; Miller, Michael G; Cholewa, Jason

2018-03-01

The purpose of this study was to compare strength, body composition, and functional outcome measures following performance of the back squat, leg press, or a combination of the two exercises. Subjects were pair-matched based on initial strength levels and then randomly assigned to 1 of 3 groups: a squat-only group (SQ) that solely performed squats for the lower body; a leg press-only group (LP) that solely performed leg presses for the lower body, or a combined squat and leg press group (SQ-LP) that performed both squats and leg presses for the lower body. All other RT variables were held constant. The study period lasted 10 weeks with subjects performing 2 lower body workouts per week comprising 6 sets per session at loads corresponding to 8-12 RM with 90- to 120-second rest intervals. Results showed that SQ had greater transfer to maximal squat strength compared to the leg press. Effect sizes favored SQ and SQ-LP versus LP with respect to countermovement jump while greater effect sizes for dynamic balance were noted for SQ-LP and LP compared to SQ, although no statistical differences were noted between conditions. These findings suggest that both free weights and machines can improve functional outcomes, and that the extent of transfer may be specific to the given task.

Influence of superplasticizer on microstructure of a 40 MPa strength concrete

International Nuclear Information System (INIS)

Teixeira, Sandra M.F.; Menezes, Raquel Maria R.O.; Figueiredo, Roberto B.; Aguilar, Maria Teresa P.; Franca, Fabricio Carlos; Bezerra, Augusto Cesar da S.

2016-01-01

The self compacting concrete has high fluidity and deformability. Studies analyze its performance through compressive strength, mortar content and / or water cement factor, which does not allow the evaluation of superplasticante influence the microstructure of these concretes. In this work, we evaluated the influence of superplasticizer comparing the phases present in a self-compacting concrete 40 MPa and at a same conventional compressive strength, same water / cement and mortar content. Therefore, scanning techniques were employed by electron microscope low vacuum using backscattered electrons and thermal analysis. The observed results show no significant differences in the microstructure of the two composites, ie the superplasticizer does not alter the microstructure of the self-compacting concrete. However, thermal analysis indicates that the present self-compacting concrete greater calcium hydroxide content which may suggest a lower content of such dry cement concrete. (author)

Effect of surface treatment of prefabricated teeth on shear bond strength of orthodontic brackets

Science.gov (United States)

Cumerlato, Marina; de Lima, Eduardo Martinelli; Osorio, Leandro Berni; Mota, Eduardo Gonçalves; de Menezes, Luciane Macedo; Rizzatto, Susana Maria Deon

2017-01-01

ABSTRACT Objective: The aim of this in vitro study was to evaluate and compare the effects of grinding, drilling, sandblasting, and ageing prefabricated teeth (PfT) on the shear bond strength (SBS) of orthodontic brackets, as well as the effects of surface treatments on the adhesive remnant index (ARI). Methods: One-hundred-ninety-two PfT were divided into four groups (n = 48): Group 1, no surface treatment was done; Group 2, grinding was performed with a cylindrical diamond bur; Group 3, two drillings were done with a spherical diamond bur; Group 4, sandblasting was performed with 50-µm aluminum oxide. Before the experiment, half of the samples stayed immersed in distilled water at 37oC for 90 days. Brackets were bonded with Transbond XT and shear strength tests were carried out using a universal testing machine. SBS were compared by surface treatment and by ageing with two-way ANOVA, followed by Tukey’s test. ARI scores were compared between surface treatments with Kruskal-Wallis test followed by Dunn’s test. Results: Surface treatments on PfT enhanced SBS of brackets (p< 0.01), result not observed with ageing (p= 0.45). Groups II, III, and IV showed higher SBS and greater ARI than the Group 1 (p< 0.05). SBS was greater in the groups 3 and 4 (drilling, sandblasting) than in the Group 2 (grinding) (p< 0.05). SBS and ARI showed a positive correlation (Spearman’s R2= 0.57; p< 0.05). Conclusion: Surface treatment on PfT enhanced SBS of brackets, however ageing did not show any relevance. Sandblasting and drilling showed greater SBS than grinding. There was a positive correlation between SBS and ARI. PMID:28902249

Effect of surface treatment of prefabricated teeth on shear bond strength of orthodontic brackets

Directory of Open Access Journals (Sweden)

Marina Cumerlato

Full Text Available ABSTRACT Objective: The aim of this in vitro study was to evaluate and compare the effects of grinding, drilling, sandblasting, and ageing prefabricated teeth (PfT on the shear bond strength (SBS of orthodontic brackets, as well as the effects of surface treatments on the adhesive remnant index (ARI. Methods: One-hundred-ninety-two PfT were divided into four groups (n = 48: Group 1, no surface treatment was done; Group 2, grinding was performed with a cylindrical diamond bur; Group 3, two drillings were done with a spherical diamond bur; Group 4, sandblasting was performed with 50-µm aluminum oxide. Before the experiment, half of the samples stayed immersed in distilled water at 37oC for 90 days. Brackets were bonded with Transbond XT and shear strength tests were carried out using a universal testing machine. SBS were compared by surface treatment and by ageing with two-way ANOVA, followed by Tukey’s test. ARI scores were compared between surface treatments with Kruskal-Wallis test followed by Dunn’s test. Results: Surface treatments on PfT enhanced SBS of brackets (p< 0.01, result not observed with ageing (p= 0.45. Groups II, III, and IV showed higher SBS and greater ARI than the Group 1 (p< 0.05. SBS was greater in the groups 3 and 4 (drilling, sandblasting than in the Group 2 (grinding (p< 0.05. SBS and ARI showed a positive correlation (Spearman’s R2= 0.57; p< 0.05. Conclusion: Surface treatment on PfT enhanced SBS of brackets, however ageing did not show any relevance. Sandblasting and drilling showed greater SBS than grinding. There was a positive correlation between SBS and ARI.

Comparison of Flexural Strength of Different CAD/CAM PMMA-Based Polymers.

Science.gov (United States)

Alp, Gülce; Murat, Sema; Yilmaz, Burak

2018-01-28

To compare the flexural strength of different computer-aided design/computer-aided manufacturing (CAD/CAM) poly(methyl methacrylate)-based (PMMA) polymers and conventional interim resin materials after thermocycling. Rectangular-shaped specimens (n = 15, for each material) (25 × 2 × 2 mm 3 ) were fabricated from 3 CAD/CAM PMMA-based polymers (Telio CAD [T]; M-PM-Disc [M]; Polident-PMMA [P]), 1 bis-acrylate composite resin (Protemp 4 [PT]), and 1 conventional PMMA (ArtConcept Artegral Dentine [C]) according to ISO 10477:2004 Standards (Dentistry-Polymer-Based Crown and Bridge Materials). The specimens were subjected to 10,000 thermocycles (5 to 55°C). Three-point flexural strength of the specimens was tested in a universal testing machine at a 1.0 mm/min crosshead speed, and the flexural strength data (σ) were calculated (MPa). The flexural strength values were statistically analyzed using 1-way ANOVA, and Tukey HSD post-hoc test for multiple comparisons (α = 0.05). Flexural strength values ranged between 66.1 ± 13.1 and 131.9 ± 19.8 MPa. There were significant differences among the flexural strengths of tested materials, except for between T and P CAD/CAM PMMA-based polymers (p > 0.05). CAD/CAM PMMA-based polymer M had the highest flexural strength and conventional PMMA had the lowest (p CAD/CAM PMMA-based T and P polymers had significantly higher flexural strength than the bis-acrylate composite resin (p CAD/CAM PMMA-based M (p CAD/CAM PMMA-based polymers was greater than the flexural strength of bis-acrylate composite resin, which had a greater flexural strength compared to conventional PMMA resin. © 2018 by the American College of Prosthodontists.

Immediate effects of kinesiotaping on quadriceps muscle strength: a single-blind, placebo-controlled crossover trial.

Science.gov (United States)

Vercelli, Stefano; Sartorio, Francesco; Foti, Calogero; Colletto, Lorenzo; Virton, Domenico; Ronconi, Gianpaolo; Ferriero, Giorgio

2012-07-01

To investigate the immediate effects on maximal muscle strength of kinesiotaping (KT) applied to the dominant quadriceps of healthy subjects. Single-blind, placebo-controlled crossover trial. "Salvatore Maugeri" Foundation. With ethical approval and informed consent, a convenience sample of 36 healthy volunteers were recruited. Two subjects did not complete the sessions and were excluded from the analysis. Subjects were tested across 3 different sessions, randomly receiving 2 experimental KT conditions applied with the aim of enhancing and inhibiting muscle strength and a sham KT application. Quadriceps muscle strength was measured by means of an isokinetic maximal test performed at 60 and 180 degrees per second. Two secondary outcome measures were performed: the single-leg triple hop for distance to measure limb performance and the Global Rating of Change Scale (GRCS) to calculate agreement between KT application and subjective perception of strength. Compared with baseline, none of the 3 taping conditions showed a significant change in muscle strength and performance (all P > 0.05). Effect size was very low under all conditions (≤0.08). Very few subjects showed an individual change greater than the minimal detectable change. Global Rating of Change Scale scores demonstrated low to moderate agreement with the type of KT applied, but some placebo effects were reported independently of condition. Our findings indicated no significant effect in the maximal quadriceps strength immediately after the application of inhibition, facilitation, or sham KT. These results do not support the use of KT applied in this way to change maximal muscle strength in healthy people.

High strength tungsten heavy alloys with molybdenum additions

International Nuclear Information System (INIS)

Bose, A.; Sims, D.M.; German, R.M.

1987-01-01

Tungsten heavy alloys are candidates for numerous applications based on the unique combination of high density, high strength, and high ductility coupled with excellent machinability. Though there has been considerable research on heavy alloys, the primary focus has been on the ductility. These alloys are well suited for ballistic uses due to their high densities and it is expected that for superior ballistic performance, a high hardness, high strength and moderate ductility alloy would be ideal. The major goal of this investigation was to obtain heavy alloys with hardness greater than HRA 72. It is evident from the phase diagrams that molybdenum, which goes into solution in tungsten, nickel and iron, could act as a potential strengthening addition. With this in view, tungsten heavy alloys with molybdenum additions were fabricated from mixed elemental powders. A baseline composition of 90W-7Ni-3Fe was chosen to its good elongation and moderate strength. The molybdenum additions were made by replacing the tungsten. Compared to the baseline properties with no molybdenum addition, the strength and hardness showed a continuous increase with molybdenum addition. The ductility of the alloy continued to decrease with increasing molybdenum content, but even with 16% wt. % molybdenum of the elongation was still around 6%. An interesting facet of these alloying additions is the grain refinement that is brought about by adding to molybdenum to the system. The grain refinement is related to the lower solubility of tunbsten in the matrix due to partial displacement by molybdenum

Association between muscle strength and metabolic syndrome in older Korean men and women: the Korean Longitudinal Study on Health and Aging.

Science.gov (United States)

Yang, Eun Joo; Lim, Soo; Lim, Jae-Young; Kim, Ki Woong; Jang, Hak Chul; Paik, Nam-Jong

2012-03-01

The objective of the study was to investigate the association between metabolic syndrome (MS) and muscle strength in community-dwelling older men and women in Korea. Korean men and women 65 years and older living in a single, typical South Korean city (n = 647) were enrolled in the Korean Longitudinal Study on Health and Aging study. The diagnosis of MS was evaluated according to the definition of the National Cholesterol Education Program Adult Treatment Panel III. Isokinetic muscle strength of the knee extensors, as determined by peak torque per body weight (newton meter per kilogram) and hand-grip strength per body weight (newton per kilogram), was measured. Participants without MS had greater leg muscle strength and grip strength per weight. The effect of MS on muscle strength was more prominent in men than in women in our study population. Only men showed a significant interaction between MS and age for muscle strength (P = .014), and the effect was greater in men aged 65 to 74 years compared with those older than 75 years (119.2 ± 31.2 vs 134.5 ± 24.3 N m/kg). Participants with MS had weaker knee extensor strength after controlling the covariates (β = -90.80, P = .003), and the interaction term (age × MS × male sex) was significant (β = 1.00, P = .017). Metabolic syndrome is associated with muscle weakness, and this relationship is particularly pronounced in men. Age can modify the impact of MS on muscle strength. Men aged 65 to 74 years with MS need a thorough assessment of muscle strength to prevent disability. Copyright © 2012 Elsevier Inc. All rights reserved.

Effects of Mental Imagery on Muscular Strength in Healthy and Patient Participants: A Systematic Review

Science.gov (United States)

Slimani, Maamer; Tod, David; Chaabene, Helmi; Miarka, Bianca; Chamari, Karim

2016-01-01

The aims of the present review were to (i) provide a critical overview of the current literature on the effects of mental imagery on muscular strength in healthy participants and patients with immobilization of the upper extremity (i.e., hand) and anterior cruciate ligament (ACL), (ii) identify potential moderators and mediators of the “mental imagery-strength performance” relationship and (iii) determine the relative contribution of electromyography (EMG) and brain activities, neural and physiological adaptations in the mental imagery-strength performance relationship. This paper also discusses the theoretical and practical implications of the contemporary literature and suggests possible directions for future research. Overall, the results reveal that the combination of mental imagery and physical practice is more efficient than, or at least comparable to, physical execution with respect to strength performance. Imagery prevention intervention was also effective in reducing of strength loss after short-term muscle immobilization and ACL. The present review also indicates advantageous effects of internal imagery (range from 2.6 to 136.3%) for strength performance compared with external imagery (range from 4.8 to 23.2%). Typically, mental imagery with muscular activity was higher in active than passive muscles, and imagining “lifting a heavy object” resulted in more EMG activity compared with imagining “lifting a lighter object”. Thus, in samples of students, novices, or youth male and female athletes, internal mental imagery has a greater effect on muscle strength than external mental imagery does. Imagery ability, motivation, and self-efficacy have been shown to be the variables mediating the effect of mental imagery on strength performance. Finally, the greater effects of internal imagery than those of external imagery could be explained in terms of neural adaptations, stronger brain activation, higher muscle excitation, greater somatic and

Anisotropic Concrete Compressive Strength

DEFF Research Database (Denmark)

Gustenhoff Hansen, Søren; Jørgensen, Henrik Brøner; Hoang, Linh Cao

2017-01-01

When the load carrying capacity of existing concrete structures is (re-)assessed it is often based on compressive strength of cores drilled out from the structure. Existing studies show that the core compressive strength is anisotropic; i.e. it depends on whether the cores are drilled parallel...

The added value of measuring thumb and finger strength when comparing strength measurements in hypoplastic thumb patients.

Science.gov (United States)

Molenaar, H M Ties; Selles, Ruud W; de Kraker, Marjolein; Stam, Henk J; Hovius, Steven E R

2013-10-01

When interventions to the hand are aimed at improving function of specific fingers or the thumb, the RIHM (Rotterdam Intrinsic Hand Myometer) is a validated tool and offers more detailed information to assess strength of the involved joints besides grip and pinch measurements. In this study, strength was measured in 65 thumbs in 40 patients diagnosed with thumb hypoplasia. These 65 thumbs were classified according to Blauth. Longitudinal radial deficiencies were also classified. The strength measurements comprised of grip, tip, tripod and key pinch. Furthermore palmar abduction and opposition of the thumb as well as abduction of the index and little finger were measured with the RIHM. For all longitudinal radial deficiency patients, grip and pinch strength as well as palmar abduction and thumb opposition were significantly lower than reference values (P<0.001). However, strength in the index finger abduction and the little finger abduction was maintained or decreased to a lesser extent according to the degree of longitudinal radial deficiency. All strength values decreased with increasing Blauth-type. Blauth-type II hands (n=15) with flexor digitorum superficialis 4 opposition transfer including stabilization of the metacarpophalangeal joint showed a trend toward a higher opposition strength without reaching statistical significance (P=0.094),however compared to non-operated Blauth-type II hands (n=6) they showed a lower grip strength (P=0.019). The RIHM is comparable in accuracy to other strength dynamometers. Using the RIHM, we were able to illustrate strength patterns on finger-specific level, showing added value when evaluating outcome in patients with hand related problems. © 2013.

Study on creep of fiber reinforced ultra-high strength concrete based on strength

Science.gov (United States)

Peng, Wenjun; Wang, Tao

2018-04-01

To complement the creep performance of ultra-high strength concrete, the long creep process of fiber reinforced concrete was studied in this paper. The long-term creep process and regularity of ultra-high strength concrete with 0.5% PVA fiber under the same axial compression were analyzed by using concrete strength (C80/C100/C120) as a variable. The results show that the creep coefficient of ultra-high strength concrete decreases with the increase of concrete strength. Compared with ACI209R (92), GL2000 models, it is found that the predicted value of ACI209R (92) are close to the experimental value, and the creep prediction model suitable for this experiment is proposed based on ACI209R (92).

Men exhibit greater fatigue resistance than women in alternated bench press and leg press exercises.

Science.gov (United States)

Monteiro, Estêvão R; Steele, James; Novaes, Jefferson S; Brown, Amanda F; Cavanaugh, Mark T; Vingren, Jakob L; Behm, David G

2017-11-17

The purpose of this study was to evaluate the influence of sex, exercise order, and rest interval on neuromuscular fatigue resistance for an alternated strength training sequence of bench press (BP) and leg press (LP) exercises. Twelve women and 16 men, both recreationally trained, performed four sessions in a random order: 1) BP followed by LP with three-minutes rest (BP+LP with rest), 2) LP followed by BP with three-minutes rest (LP+BP with rest), 3) BP followed by LP without rest interval (BP+LP no rest), and 4) LP followed by BP without rest interval (LP+BP no rest). Participants performed four sets with 100% of 10RM load to concentric failure with the goal of completing the maximum number of repetitions in both exercises. The fatigue index was analyzed from the first and last sets of each exercise bout. A main effect for sex showed that women exhibited 25.5% (p=0.001) and 24.5% (p=0.001) greater BP and LP fatigue than men respectively when performing 10RM. Men exhibited greater BP (p<0.0001; 34.1%) and LP (p<0.0001; 30.5%) fatigue resistance when a rest period was provided. Men did not show an exercise order effect for BP fatigue and exhibited greater (p=0.0003; 14.5%) LP fatigue resistance when BP was performed first. The present study demonstrated the greater fatigue resistance of men when performing 10RM BP and LP exercises. Since men tend to experience less fatigue with the second exercise in the exercise pairing, women's training programs should be adjusted to ensure they do not parallel men's resistance training programs.

The healthy Nordic diet predicts muscle strength 10 years later in old women, but not old men.

Science.gov (United States)

Perälä, Mia-Maria; von Bonsdorff, Mikaela B; Männistö, Satu; Salonen, Minna K; Simonen, Mika; Kanerva, Noora; Rantanen, Taina; Pohjolainen, Pertti; Eriksson, Johan G

2017-07-01

a number of nutrients have been found to be associated with better muscle strength and mass; however, the role of the whole diet on muscle strength and mass remains still unknown. to examine whether the healthy Nordic diet predicts muscle strength, and mass 10 years later among men and women. about 1,072 participants belong to the Helsinki Birth Cohort Study, born 1934-44. Diet was assessed with a validated food-frequency questionnaire during 2001-04. The Nordic diet score (NDS) was calculated. The score included Nordic fruits, vegetables, cereals, ratio of polyunsaturated to saturated fatty acids, low-fat milk, fish, red meat, total fat and alcohol. Higher scores indicated better adherence to the healthy Nordic diet. Hand grip strength, leg strength (knee extension) and muscle mass were measured during the follow-up, between 2011 and 2013. in women, each 1-unit increase in the NDS was related to 1.83 N greater leg strength (95% confidence interval [CI] 0.14-3.51; P = 0.034), and 1.44 N greater hand grip strength (95% CI: 0.04-2.84; P = 0.044). Women in the highest quartile of the NDS had on average 20.0 N greater knee extension results, and 14.2 N greater hand grip results than those in the lowest quartile. No such associations were observed among men. The NDS was not significantly related to muscle mass either in men or women. adherence to the healthy Nordic diet seems to protect from weaker muscle strength in old women. Therefore, the healthy Nordic diet may help to prevent disability. © The Author 2017. Published by Oxford University Press on behalf of the British Geriatrics Society.All rights reserved. For permissions, please email: journals.permissions@oup.com

Influence of the mechanical properties of lime mortar on the strength of brick masonry

OpenAIRE

PAVIA, SARA

2013-01-01

PUBLISHED This paper aims at improving the quality of lime mortar masonry by understanding the mechanics of mortars and masonry and their interaction. It investigates how the mortar?s compressive and flexural strengths impact the compressive and bond strength of clay brick masonry bound with calcium lime (CL) and natural hydraulic lime (NHL) mortars. It concludes that the strength of the bond has a greater impact on the compressive strength of masonry than the mortar?s st...

The ancestral logic of politics: upper-body strength regulates men's assertion of self-interest over economic redistribution.

Science.gov (United States)

Petersen, Michael Bang; Sznycer, Daniel; Sell, Aaron; Cosmides, Leda; Tooby, John

2013-07-01

Over human evolutionary history, upper-body strength has been a major component of fighting ability. Evolutionary models of animal conflict predict that actors with greater fighting ability will more actively attempt to acquire or defend resources than less formidable contestants will. Here, we applied these models to political decision making about redistribution of income and wealth among modern humans. In studies conducted in Argentina, Denmark, and the United States, men with greater upper-body strength more strongly endorsed the self-beneficial position: Among men of lower socioeconomic status (SES), strength predicted increased support for redistribution; among men of higher SES, strength predicted increased opposition to redistribution. Because personal upper-body strength is irrelevant to payoffs from economic policies in modern mass democracies, the continuing role of strength suggests that modern political decision making is shaped by an evolved psychology designed for small-scale groups.

Fish-oil supplementation enhances the effects of strength training in elderly women.

Science.gov (United States)

Rodacki, Cintia L N; Rodacki, André L F; Pereira, Gleber; Naliwaiko, Katya; Coelho, Isabela; Pequito, Daniele; Fernandes, Luiz Cléudio

2012-02-01

Muscle force and functional capacity generally decrease with aging in the older population, although this effect can be reversed, attenuated, or both through strength training. Fish oil (FO), which is rich in n-3 (omega-3) PUFAs, has been shown to play a role in the plasma membrane and cell function of muscles, which may enhance the benefits of training. The effect of strength training and FO supplementation on the neuromuscular system of the elderly has not been investigated. The objective was to investigate the chronic effect of FO supplementation and strength training on the neuromuscular system (muscle strength and functional capacity) of older women. Forty-five women (aged 64 ± 1.4 y) were randomly assigned to 3 groups. One group performed strength training only (ST group) for 90 d, whereas the others performed the same strength-training program and received FO supplementation (2 g/d) for 90 d (ST90 group) or for 150 d (ST150 group; supplemented 60 d before training). Muscle strength and functional capacity were assessed before and after the training period. No differences in the pretraining period were found between groups for any of the variables. The peak torque and rate of torque development for all muscles (knee flexor and extensor, plantar and dorsiflexor) increased from pre- to posttraining in all groups. However, the effect was greater in the ST90 and ST150 groups than in the ST group. The activation level and electromechanical delay of the muscles changed from pre- to posttraining only for the ST90 and ST150 groups. Chair-rising performance in the FO groups was higher than in the ST group. Strength training increased muscle strength in elderly women. The inclusion of FO supplementation caused greater improvements in muscle strength and functional capacity.

Lifting strength in two-person teamwork.

Science.gov (United States)

Lee, Tzu-Hsien

2016-01-01

This study examined the effects of lifting range, hand-to-toe distance, and lifting direction on single-person lifting strengths and two-person teamwork lifting strengths. Six healthy males and seven healthy females participated in this study. Two-person teamwork lifting strengths were examined in both strength-matched and strength-unmatched groups. Our results showed that lifting strength significantly decreased with increasing lifting range or hand-to-toe distance. However, lifting strengths were not affected by lifting direction. Teamwork lifting strength did not conform to the law of additivity for both strength-matched and strength-unmatched groups. In general, teamwork lifting strength was dictated by the weaker of the two members, implying that weaker members might be exposed to a higher potential danger in teamwork exertions. To avoid such overexertion in teamwork, members with significantly different strength ability should not be assigned to the same team.

Increased residual force enhancement in older adults is associated with a maintenance of eccentric strength.

Directory of Open Access Journals (Sweden)

Geoffrey A Power

Full Text Available Despite an age-related loss of voluntary isometric and concentric strength, muscle strength is well maintained during lengthening muscle actions (i.e., eccentric strength in old age. Additionally, in younger adults during lengthening of an activated skeletal muscle, the force level observed following the stretch is greater than the isometric force at the same muscle length. This feature is termed residual force enhancement (RFE and is believed to be a combination of active and passive components of the contractile apparatus. The purpose of this study was to provide an initial assessment of RFE in older adults and utilize aging as a muscle model to explore RFE in a system in which isometric force production is compromised, but structural mechanisms of eccentric strength are well-maintained. Therefore, we hypothesised that older adults will experience greater RFE compared with young adults. Following a reference maximal voluntary isometric contraction (MVC of the dorsiflexors in 10 young (26.1 ± 2.7 y and 10 old (76.0 ± 6.5 y men, an active stretch was performed at 15°/s over a 30° ankle joint excursion ending at the same muscle length as the reference MVCs (40° of plantar flexion. Any additional torque compared with the reference MVC therefore represented RFE. In older men RFE was ~2.5 times greater compared to young. The passive component of force enhancement contributed ~37% and ~20% to total force enhancement, in old and young respectively. The positive association (R(2 = 0.57 between maintained eccentric strength in old age and RFE indicates age-related mechanisms responsible for the maintenance of eccentric strength likely contributed to the observed elevated RFE. Additionally, as indicated by the greater passive force enhancement, these mechanisms may be related to increased muscle series elastic stiffness in old age.

Mapping strengths into virtues: The relation of the 24 VIA-strengths to six ubiquitous virtues

Directory of Open Access Journals (Sweden)

Willibald eRuch

2015-04-01

Full Text Available The Values-in-Action (VIA-classification distinguishes six core virtues and 24 strengths. As the assignment of the strengths to the virtues was done on theoretical grounds it still needs empirical verification. As an alternative to factor analytic investigations the present study utilizes expert judgments. In a pilot study the conceptual overlap among five sources of knowledge (strength’s name including synonyms, short definitions, brief descriptions, longer theoretical elaborations, and item content about a particular strength was examined. The results show that the five sources converged quite well, with the short definitions and the items being slightly different from the other. All strengths exceeded a cut-off value but the convergence was much better for some strengths (e.g., zest than for others (e.g., perspective. In the main study 70 experts (from psychology, philosophy, theology, etc. and 41 laypersons rated how prototypical the strengths are for each of the six virtues. The results showed that 10 were very good markers for their virtues, 9 were good markers, four were acceptable markers, and only one strength failed to reach the cut-off score for its assigned virtue. However, strengths were often markers for two or even three virtues, and occasionally they marked the other virtue more strongly than the one they were assigned to. The virtue prototypicality ratings were slightly positively correlated with higher coefficients being found for justice and humanity. A factor analysis of the 24 strengths across the ratings yielded the six factors with an only slightly different composition of strengths and double loadings. It is proposed to adjust either the classification (by reassigning strengths and by allowing strengths to be subsumed under more than one virtue or to change the definition of certain strengths so that they only exemplify one virtue. The results are discussed in the context of factor analytic attempts to verify the

Fatigue strength of repaired cracks in welded connections made of very high strength steels

NARCIS (Netherlands)

Akyel, A.

2017-01-01

For cyclically loaded structures, fatigue design becomes one of the important design criteria. The state of art shows that with modification of the conventional structural design methodology, the use of very high strength steels may have a positive effect on fatigue strength of welded connections.

Slippage of steel in high and normal strength concrete

International Nuclear Information System (INIS)

Ahmed, K.; Siddiqi, Z.A.; Yousaf, M.

2007-01-01

Composite action of any reinforced concrete member is only possible if sufficient bond strength exists between steel reinforcing bars and concrete, which can adequately transfer shear stress between them. Bond strength is a function of compressive strength of concrete and hence high strength concrete has higher bond strength (1-2). Therefore required development length can be reduced. In order to investigate the effect of development length on bond stress and slip relationships, experimental investigation was carried out. In this experimentation 24 pull-out samples of high strength concrete and normal strength concrete were casted and tested. The results of this investigation revealed that by increasing the development length from 5db to 10db bond strength increases for both high and normal strength concrete as shown in Figure 11, 12 and 13. However in case of normal strength concrete increase in bond strength is more compared to that in high strength concrete as it is clear from Figure 11 and Figure 13. The increase in bond strength is observed even at 10db development length but the extent is less for 19 mm than 16 mm bars as shown in Figure 12 and Figure 13. This is in agreement with the earlier findings of Chen et al (3) and Harajli et al (1). However in case of HSC the total slippage at 10db is 50% greater than at 5db. This may be due to the fact that more no of concrete keys participate in resisting the slippage. (author)

Influence of multiaxial preloading on the strength of concrete

International Nuclear Information System (INIS)

Linse, D.

1975-01-01

In a preliminary study about the influence of the loading direction discs of 20/20/5 cm were loaded at different stress-rates in one direction, then unloaded and loaded up to failure again. Two series of each about 15 specimens were tested: the first series was reloaded in the same direction as it was loaded before. If the preloading was not greater than about 90% of the original short-term uniaxial strength βsub(p), one could achieve in the second loading a higher strength than the strength βsub(p). The second series was reloaded normal to the direction of preloading. By an other series of about 50 specimens the influence of triaxial preloading on the uniaxial strength of concrete was tested. Cubes of 10cm were loaded by brush bearing platens up to a stress which was maximally three times higher than the uniaxial short-term strength βsub(p), then unloaded and tested again under uniaxial compression. The achieved ultimate strength of the cubes at the second loading was obviously dependent upon the stress-state and the stress-rate of the preloading. Multiaxial preloading which is far below the ultimate multiaxial strength can considerably defect the remaining strength of concrete. The decrease in strength was defined by the reduction of the uniaxial strength. It can be assumed that the remaining multiaxial strength is reduced at least to the same rate. Further tests are planned

Effects of different strength training frequencies on maximum strength, body composition and functional capacity in healthy older individuals.

Science.gov (United States)

Turpela, Mari; Häkkinen, Keijo; Haff, Guy Gregory; Walker, Simon

2017-11-01

There is controversy in the literature regarding the dose-response relationship of strength training in healthy older participants. The present study determined training frequency effects on maximum strength, muscle mass and functional capacity over 6months following an initial 3-month preparatory strength training period. One-hundred and six 64-75year old volunteers were randomly assigned to one of four groups; performing strength training one (EX1), two (EX2), or three (EX3) times per week and a non-training control (CON) group. Whole-body strength training was performed using 2-5 sets and 4-12 repetitions per exercise and 7-9 exercises per session. Before and after the intervention, maximum dynamic leg press (1-RM) and isometric knee extensor and plantarflexor strength, body composition and quadriceps cross-sectional area, as well as functional capacity (maximum 7.5m forward and backward walking speed, timed-up-and-go test, loaded 10-stair climb test) were measured. All experimental groups increased leg press 1-RM more than CON (EX1: 3±8%, EX2: 6±6%, EX3: 10±8%, CON: -3±6%, Ptraining frequency would induce greater benefit to maximum walking speed (i.e. functional capacity) despite a clear dose-response in dynamic 1-RM strength, at least when predominantly using machine weight-training. It appears that beneficial functional capacity improvements can be achieved through low frequency training (i.e. 1-2 times per week) in previously untrained healthy older participants. Copyright © 2017 Elsevier Inc. All rights reserved.

Effects of Mental Imagery on Muscular Strength in Healthy and Patient Participants: A Systematic Review

Directory of Open Access Journals (Sweden)

Maamer Slimani, David Tod, Helmi Chaabene, Bianca Miarka, Karim Chamari

2016-09-01

Full Text Available The aims of the present review were to (i provide a critical overview of the current literature on the effects of mental imagery on muscular strength in healthy participants and patients with immobilization of the upper extremity (i.e., hand and anterior cruciate ligament (ACL, (ii identify potential moderators and mediators of the “mental imagery-strength performance” relationship and (iii determine the relative contribution of electromyography (EMG and brain activities, neural and physiological adaptations in the mental imagery-strength performance relationship. This paper also discusses the theoretical and practical implications of the contemporary literature and suggests possible directions for future research. Overall, the results reveal that the combination of mental imagery and physical practice is more efficient than, or at least comparable to, physical execution with respect to strength performance. Imagery prevention intervention was also effective in reducing of strength loss after short-term muscle immobilization and ACL. The present review also indicates advantageous effects of internal imagery (range from 2.6 to 136.3% for strength performance compared with external imagery (range from 4.8 to 23.2%. Typically, mental imagery with muscular activity was higher in active than passive muscles, and imagining “lifting a heavy object” resulted in more EMG activity compared with imagining “lifting a lighter object”. Thus, in samples of students, novices, or youth male and female athletes, internal mental imagery has a greater effect on muscle strength than external mental imagery does. Imagery ability, motivation, and self-efficacy have been shown to be the variables mediating the effect of mental imagery on strength performance. Finally, the greater effects of internal imagery than those of external imagery could be explained in terms of neural adaptations, stronger brain activation, higher muscle excitation, greater somatic

Anthropometric, biomechanical, and isokinetic strength predictors of ball release speed in high-performance cricket fast bowlers.

Science.gov (United States)

Wormgoor, Shohn; Harden, Lois; Mckinon, Warrick

2010-07-01

Fast bowling is fundamental to all forms of cricket. The purpose of this study was to identify parameters that contribute to high ball release speeds in cricket fast bowlers. We assessed anthropometric dimensions, concentric and eccentric isokinetic strength of selected knee and shoulder muscle groups, and specific aspects of technique from a single delivery in 28 high-performance fast bowlers (age 22.0 +/- 3.0 years, ball release speed 34.0 +/- 1.3 m s(-1)). Six 50-Hz cameras and the Ariel Performance Analysis System software were used to analyse the fast and accurate deliveries. Using Pearson's correlation, parameters that showed significant associations with ball release speed were identified. The findings suggest that greater front leg knee extension at ball release (r=0.52), shoulder alignment in the transverse plane rotated further away from the batsman at front foot strike (r=0.47), greater ankle height during the delivery stride (r=0.44), and greater shoulder extension strength (r=0.39) contribute significantly to higher ball release speeds. Predictor variables failed to allow their incorporation into a multivariate model, which is known to exist in less accomplished bowlers, suggesting that factors that determine ball release speed found in other groups may not apply to high-performance fast bowlers.

Older Adults with Weaker Muscle Strength Stand up from a Sitting Position with More Dynamic Trunk Use

Directory of Open Access Journals (Sweden)

Rob C. van Lummel

2018-04-01

Full Text Available The ability to stand up from a sitting position is essential for older adults to live independently. Body-fixed inertial sensors may provide an approach for quantifying the sit-to-stand (STS in clinical settings. The aim of this study was to determine whether measurements of STS movements using body-fixed sensors yield parameters that are informative regarding changes in STS performance in older adults with reduced muscle strength. In twenty-seven healthy older adults, handgrip strength was assessed as a proxy for overall muscle strength. Subjects were asked to stand up from a chair placed at three heights. Trunk movements were measured using an inertial sensor fixed to the back. Duration, angular range, and maximum angular velocity of STS phases, as well as the vertical velocity of the extension phase, were calculated. Backwards elimination using Generalized Estimating Equations was used to determine if handgrip strength predicted the STS durations and trunk kinematics. Weaker subjects (i.e., with lower handgrip strength were slower during the STS and showed a larger flexion angular range and a larger extension angular range. In addition, weaker subjects showed a greater maximum angular velocity, which increased with lower seat heights. Measurements with a single inertial sensor did reveal that older adults with lower handgrip strength employed a different strategy to stand up from a sitting position, involving more dynamic use of the trunk. This effect was greatest when elevating body mass. Trunk kinematic parameters were more sensitive to reduced muscle strength than durations.

Handgrip strength shows no improvements in geriatric patients with persistent inflammation during hospitalization

DEFF Research Database (Denmark)

Norheim, Kristoffer Larsen; Bautmans, Ivan; Kjaer, Michael

2017-01-01

PURPOSE: Hospital-associated deconditioning due to a combination of illness and inactivity is a serious problem for elderly adults. Here we investigate whether persistence in inflammatory status affects changes in physical function during short-term hospitalization. METHODS: This was a prospective...... observational study in elderly medical patients at a geriatric department. Measurements were obtained at admission and one week after admission and included de Morton Mobility Index (DEMMI) test, 30-second chair stand test (30-s CST), 4-m gait speed (4-m GST) test, handgrip strength, activity levels determined...... with ActivPALs, and concentrations of circulating C-reactive protein (CRP) from blood samples. Only patients with inflammation (C-reactive protein levels ≥10mg·L(-1)) at admission were included in this study. They were divided into those with continued inflammation (CI: CRP remained ≥10mg·L(-1)) and those...

The Effect of Body Mass on Eccentric Knee-Flexor Strength Assessed With an Instrumented Nordic Hamstring Device (Nordbord) in Football Players.

Science.gov (United States)

Buchheit, Martin; Cholley, Yannick; Nagel, Mark; Poulos, Nicholas

2016-09-01

To examine the effect of body mass (BM) on eccentric knee-flexor strength using the Nordbord and offer simple guidelines to control for the effect of BM on knee-flexor strength. Data from 81 soccer players (U17, U19, U21, senior 4th French division, and professionals) and 41 Australian Football League (AFL) players were used for analysis. They all performed 1 set of 3 maximal repetitions of the bilateral Nordic hamstring exercise, with the greatest strength measure used for analysis. The main regression equation obtained from the overall sample was used to predict eccentric knee-flexor strength from a given BM (moderate TEE, 22%). Individual deviations from the BM-predicted score were used as a BM-free index of eccentric knee- flexor strength. There was a large (r = .55, 90% confidence limits .42;.64) correlation between eccentric knee-flexor strength and BM. Heavier and older players (professionals, 4th French division, and AFL) outperformed their lighter and younger (U17-U21) counterparts, with the soccer professionals presenting the highest absolute strength. Professional soccer players were the only ones to show strength values likely slightly greater than those expected for their BM. Eccentric knee-flexor strength, as assessed with the Nordbord, is largely BM-dependent. To control for this effect, practitioners may compare actual test performances with the expected strength for a given BM, using the following predictive equation: Eccentric strength (N) = 4 × BM (kg) + 26.1. Professional soccer players with specific knee-flexor-training history and enhanced neuromuscular performance may show higher than expected values.

The assessment of bond strength between heat damaged concrete and high strength fibre reinforced concrete

Science.gov (United States)

Zahid, M. Z. A. Mohd; Muhamad, K.

2017-09-01

The aim of this study is to assess the bond strength between heat damaged concrete and high strength fibre reinforced concrete (HPFRC). Firstly, this paper presents the various steps taken to prepare the HPFRC with self-compacting property. The minimum targeted slump flow is 600 mm and minimum targeted compressive strength is 80 MPa. The key mix variables considered are such as type of superplasticizer, water cement ratio and silica fume content. Then, the bond strength between the heat damaged concrete with HPFRC was examined. The experimental parameters are heating temperature, surface treatment technique and curing method and the results show that, all experimental parameters are significantly affected the bond strength between heat damaged concrete and HPFRC.

Responses to LBNP in men with varying profiles of strength and aerobic capacity: Implications for flight crews

Science.gov (United States)

Convertino, Victor A.; Mathes, Karen L.; Lasley, Mary L.; Tomaselli, Clare Marie; Frey, Mary Anne Bassett; Hoffler, G. Wyckliffe

1993-01-01

Hemodynamic and hormonal responses to lower-body negative pressure (LBNP) were examined in 24 healthy men to test the hypothesis that responsiveness of reflex control of blood pressure during orthostatic stress is associated with strength and/or aerobic capacity. Subjects underwent treadmill tests to determine peak oxygen uptake (peak VO2) and isokinetic dynamo meter tests to determine leg strength. Based on predetermined criteria, the subjects were classified into one of four fitness profiles of six subjects each matched for age, height, and weight: (1) low strength/low aerobic fitness; (2) low strength/high aerobic fitness; (3) high strength/low aerobic fitness; and (4) high strength/high aerobic fitness. Following 90 min of 6 degree head-down tilt (HDT), each subject underwent graded LBNP through -50 mmHg or presyncope, with maximal duration 15 min. All groups exhibited typical hemodynamic, hormonal, and fluid shift responses during LBNP, with no intergroup differences except for catecholamines. Seven subjects, distributed among the four fitness profiles, became presyncopal. Subjects who showed greatest reduction in mean arterial pressure (MAP) during LBNP had greater elevations in vasopressin and lesser increases in heart rate and peripheral resistance. Peak VO2 nor leg strength were correlated with fall in MAP or with syncopal episodes. We conclude that neither aerobic nor strength fitness characteristics are good predictors of responses to LBNP stress.

Compressive strength, flexural strength and water absorption of concrete containing palm oil kernel shell

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Noor, Nurazuwa Md; Xiang-ONG, Jun; Noh, Hamidun Mohd; Hamid, Noor Azlina Abdul; Kuzaiman, Salsabila; Ali, Adiwijaya

2017-11-01

Effect of inclusion of palm oil kernel shell (PKS) and palm oil fibre (POF) in concrete was investigated on the compressive strength and flexural strength. In addition, investigation of palm oil kernel shell on concrete water absorption was also conducted. Total of 48 concrete cubes and 24 concrete prisms with the size of 100mm × 100mm × 100mm and 100mm × 100mm × 500mm were prepared, respectively. Four (4) series of concrete mix consists of coarse aggregate was replaced by 0%, 25%, 50% and 75% palm kernel shell and each series were divided into two (2) main group. The first group is without POF, while the second group was mixed with the 5cm length of 0.25% of the POF volume fraction. All specimen were tested after 7 and 28 days of water curing for a compression test, and flexural test at 28 days of curing period. Water absorption test was conducted on concrete cube age 28 days. The results showed that the replacement of PKS achieves lower compressive and flexural strength in comparison with conventional concrete. However, the 25% replacement of PKS concrete showed acceptable compressive strength which within the range of requirement for structural concrete. Meanwhile, the POF which should act as matrix reinforcement showed no enhancement in flexural strength due to the balling effect in concrete. As expected, water absorption was increasing with the increasing of PKS in the concrete cause by the porous characteristics of PKS

Blind Man Shows His Strength

Institute of Scientific and Technical Information of China (English)

1994-01-01

IN 1992 Huang Wentao, 22, set a world record in the disabled long jump. Before he set this record, his parents had never thought of letting him do sports. He is the second son of Liu Linzhi. When Liu got pregnant again, she felt happy and at ease. She wanted to have a beautiful girl because she thought she would then be satisfied, having one son and one daughter. Of course it would also be all right if she had a second son like her first child. The two brothers could take care of each other and be friends. The child, a good-looking boy, came into the world safely. Like most babies, newborn Huang sometimes cried, sometimes opened his big eyes and

Effects of walking and strength training on walking capacity in individuals with claudication: meta-analysis

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Alessandra de Souza Miranda

2013-06-01

Full Text Available CONTEXT: Over the past few years, several clinical trials have been performed to analyze the effects of exercise training on walking ability in patients with intermittent claudication (IC. However, it remains unclear which type of physical exercise provides the maximum benefits in terms of walking ability. OBJECTIVE: To analyze, by means of a meta-analysis, the effects of walking and strength training on the walking capacity in patients with IC. METHODS: Papers analyzing the effects of walking and strength training programs in patients with IC were browsed on the Medline, Lilacs, and Cochrane databases. Randomized clinical trials scoring >4 on the Physiotherapy Evidence Database (PEDro scale and assessing claudication distance (CD and total walking distance (TWD were included in the review. RESULTS: Walking and strength training yielded increases in CD and TWD (P < 0.05. However, walking training yielded greater increases than strength training (P = 0.02. CONCLUSION: Walking and strength training improve walking capacity in patients with IC. However, greater improvements in TWD are obtained with walking training.

Analysis of the Strength on the Rotor Punching Sheet of Nuclear Reactor Cooling Medium Driving Motor

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GE Bao-jun

2017-02-01

Full Text Available A strong stress is withstood by the rotor punching sheet during the running of nuclear reactor cooling medium driving motor. In order to study the strength on the rotor punching sheet and the influential factor of its stress，the rotor of driving motor was the research object, the three-dimensional rotor model of driving motor is established by the finite element method to obtain the Mires equivalent stress nephogram and check the rotor’s strength with setting parameters and constraints. According to different rotor speeds，the different average temperatures of rotor punching sheet and shaft and the different static magnitude of interference between rotor punching sheet and shaft，the research about how the contact pressure of matching surface between rotor punching sheet and shaft and the Mires equivalent stress are impacted is carried on. The results show that the maximum Miser equivalent stress value of rotor punching sheet emerges on the axial vents，the stress value is beyond the tensile limit of the materialand. The greater the static magnitude of interference and the smaller temperature difference of rotor punching sheet and shaft lead to the greater interface compressive stress of rotor punching sheet and shaft and the greater maximum Mires equivalent stress value of rotor punching sheet. The higher the rotor speed lead to the smaller interface compressive stress of rotor punching sheet and shaft and the greater equivalent stress value of rotor punching sheet.

Personality Strengths as Resilience: A One-Year Multiwave Study.

Science.gov (United States)

Goodman, Fallon R; Disabato, David J; Kashdan, Todd B; Machell, Kyla A

2017-06-01

We examined how personality strengths prospectively predict reactions to negative life events. Participants were 797 community adults from 42 countries. At five points over the course of 1 year, participants completed a series of questionnaires measuring seven personality strengths (hope, grit, meaning in life, curiosity, gratitude, control beliefs, and use of strengths), subjective well-being, and frequency and severity of negative life events. Using hierarchical linear modeling with assessment periods nested within participants, results from lagged analyses found that only hope emerged as a resilience factor. To illustrate the importance of using appropriate lagged analyses in resilience research, we ran nonlagged analyses; these results suggest that all seven personality strengths moderated the effect of negative life events on subjective well-being, with greater strengths associated with healthier outcomes. To provide evidence that personality strengths confer resilience, a prospective examination is needed with the inclusion of events and responses to them. The use of concurrent methodologies and analyses, which is the norm in psychology, often leads to erroneous conclusions. Hope, the ability to generate routes to reach goals and the motivation to use those routes, was shown to be particularly important in promoting resilience. © 2016 Wiley Periodicals, Inc.

The adhesive strength and initial viscosity of denture adhesives.

Science.gov (United States)

Han, Jian-Min; Hong, Guang; Dilinuer, Maimaitishawuti; Lin, Hong; Zheng, Gang; Wang, Xin-Zhi; Sasaki, Keiichi

2014-11-01

To examine the initial viscosity and adhesive strength of modern denture adhesives in vitro. Three cream-type denture adhesives (Poligrip S, Corect Cream, Liodent Cream; PGS, CRC, LDC) and three powder-type denture adhesives (Poligrip Powder, New Faston, Zanfton; PGP, FSN, ZFN) were used in this study. The initial viscosity was measured using a controlled-stress rheometer. The adhesive strength was measured according to ISO-10873 recommended procedures. All data were analyzed independently by one-way analysis of variance combined with a Student-Newman-Keuls multiple comparison test at a 5% level of significance. The initial viscosity of all the cream-type denture adhesives was lower than the powder-type adhesives. Before immersion in water, all the powder-type adhesives exhibited higher adhesive strength than the cream-type adhesives. However, the adhesive strength of cream-type denture adhesives increased significantly and exceeded the powder-type denture adhesives after immersion in water. For powder-type adhesives, the adhesive strength significantly decreased after immersion in water for 60 min, while the adhesive strength of the cream-type adhesives significantly decreased after immersion in water for 180 min. Cream-type denture adhesives have lower initial viscosity and higher adhesive strength than powder type adhesives, which may offer better manipulation properties and greater efficacy during application.

Effect of concrete strength gradation to the compressive strength of graded concrete, a numerical approach

Science.gov (United States)

Pratama, M. Mirza Abdillah; Aylie, Han; Gan, Buntara Sthenly; Umniati, B. Sri; Risdanareni, Puput; Fauziyah, Shifa

2017-09-01

Concrete casting, compacting method, and characteristic of the concrete material determine the performance of concrete as building element due to the material uniformity issue. Previous studies show that gradation in strength exists on building member by nature and negatively influence the load carrying capacity of the member. A pilot research had modeled the concrete gradation in strength with controllable variable and observed that the weakest material determines the strength of graded concrete through uniaxial compressive loading test. This research intends to confirm the recent finding by a numerical approach with extensive variables of strength disparity. The finite element analysis was conducted using the Strand7 nonlinear program. The results displayed that the increase of strength disparity in graded concrete models leads to the slight reduction of models strength. A substantial difference in displacement response is encountered on the models for the small disparity of concrete strength. However, the higher strength of concrete mix in the graded concrete models contributes to the rise of material stiffness that provides a beneficial purpose for serviceability of building members.

Strength training for the warfighter.

Science.gov (United States)

Kraemer, William J; Szivak, Tunde K

2012-07-01

Optimizing strength training for the warfighter is challenged by past training philosophies that no longer serve the modern warfighter facing the "anaerobic battlefield." Training approaches for integration of strength with other needed physical capabilities have been shown to require a periodization model that has the flexibility for changes and is able to adapt to ever-changing circumstances affecting the quality of workouts. Additionally, sequencing of workouts to limit over-reaching and development of overtraining syndromes that end in loss of duty time and injury are paramount to long-term success. Allowing adequate time for rest and recovery and recognizing the negative influences of extreme exercise programs and excessive endurance training will be vital in moving physical training programs into a more modern perspective as used by elite strength-power anaerobic athletes in sports today. Because the warfighter is an elite athlete, it is time that training approaches that are scientifically based are updated within the military to match the functional demands of modern warfare and are given greater credence and value at the command levels. A needs analysis, development of periodized training modules, and individualization of programs are needed to optimize the strength of the modern warfighter. We now have the knowledge, professional coaches and nonprofit organization certifications with continuing education units, and modern training technology to allow this to happen. Ultimately, it only takes command decisions and implementation to make this possible.

Strength development in concrete with wood ash blended cement and use of soft computing models to predict strength parameters.

Science.gov (United States)

Chowdhury, S; Maniar, A; Suganya, O M

2015-11-01

In this study, Wood Ash (WA) prepared from the uncontrolled burning of the saw dust is evaluated for its suitability as partial cement replacement in conventional concrete. The saw dust has been acquired from a wood polishing unit. The physical, chemical and mineralogical characteristics of WA is presented and analyzed. The strength parameters (compressive strength, split tensile strength and flexural strength) of concrete with blended WA cement are evaluated and studied. Two different water-to-binder ratio (0.4 and 0.45) and five different replacement percentages of WA (5%, 10%, 15%, 18% and 20%) including control specimens for both water-to-cement ratio is considered. Results of compressive strength, split tensile strength and flexural strength showed that the strength properties of concrete mixture decreased marginally with increase in wood ash contents, but strength increased with later age. The XRD test results and chemical analysis of WA showed that it contains amorphous silica and thus can be used as cement replacing material. Through the analysis of results obtained in this study, it was concluded that WA could be blended with cement without adversely affecting the strength properties of concrete. Also using a new statistical theory of the Support Vector Machine (SVM), strength parameters were predicted by developing a suitable model and as a result, the application of soft computing in structural engineering has been successfully presented in this research paper.

Porosimetric, Thermal and Strength Tests of Aerated and Nonaerated Concretes

Science.gov (United States)

Strzałkowski, Jarosław; Garbalińska, Halina

2017-10-01

The paper presents the results of porosimetry tests of lightweight concretes, obtained with three research methods. Impact of different porosity structures on the basic thermal and strength properties was also evaluated. Tests were performed, using the pressure gauge method on fresh concrete mixes, as well as using the mercury porosimetry test and optic RapidAir method on specimens prepared from mature composites. The study was conducted on lightweight concretes, based on expanded clay aggregate and fly ash aggregate, in two variants: with non-aerated and aerated cement matrix. In addition, two reference concretes, based on normal aggregate, were prepared, also in two variants of matrix aeration. Changes in thermal conductivity λ and volumetric specific heat cv throughout the first three months of curing of the concretes were examined. Additionally, tests for compressive strength on cubic samples were performed during the first three months of curing. It was found that the pressure gauge method, performed on a fresh mix, gave lowered values of porosity, compared to the other methods. The mercury porosity tests showed high sensitivity in evaluation of pores smaller than 30μm. Unfortunately, this technique is not suitable for analysing pores greater than 300μm. On the other hand, the optical method proves good in evaluation of large pores, greater than 300μm. The paper also presents results of correlation of individual methods of porosity testing. A consolidated graph of the pore structure, derived from both mercury and optical methods, was presented, too. For the all of six tested concretes, differential graphs of porosity, prepared with both methods, show a very broad convergence. The thermal test results indicate usefulness of aeration of the cement matrix of the composites based on lightweight aggregates for the further reduction of the thermal conductivity coefficient λ of the materials. The lowest values of the λ coefficient were obtained for the aerated

Short-term Periodization Models: Effects on Strength and Speed-strength Performance.

Science.gov (United States)

Hartmann, Hagen; Wirth, Klaus; Keiner, Michael; Mickel, Christoph; Sander, Andre; Szilvas, Elena

2015-10-01

least 1-2 days before competition because of the shorter regeneration times and potentiation effects. Compared with ballistic strength training (30% 1 RM), this method has been shown to provide statistically superior gains in maximal strength, peak power, impulse size, and explosive strength during tapering in track-and-field throwers. The speed-strength performance in drop jumps of strength-trained subjects showed potentiation effects 48-148 h after a single strength-power training session. Regarding neuromuscular performance, plyometric exercises can even be performed after strength-power training on the same day if a minimum rest period of 3 h is provided.

modified water-cement ratio law for compressive strength of rice

African Journals Online (AJOL)

user

various types of structures due to its structural stability and strength [1]. ... value of water-cement ratio results in greater pore spaces in .... as well as removing the excess water on the surface of the soil particles. ... and aggregate impact value.

Burst strength of tubing and casing based on twin shear unified strength theory.

Science.gov (United States)

Lin, Yuanhua; Deng, Kuanhai; Sun, Yongxing; Zeng, Dezhi; Liu, Wanying; Kong, Xiangwei; Singh, Ambrish

2014-01-01

The internal pressure strength of tubing and casing often cannot satisfy the design requirements in high pressure, high temperature and high H2S gas wells. Also, the practical safety coefficient of some wells is lower than the design standard according to the current API 5C3 standard, which brings some perplexity to the design. The ISO 10400: 2007 provides the model which can calculate the burst strength of tubing and casing better than API 5C3 standard, but the calculation accuracy is not desirable because about 50 percent predictive values are remarkably higher than real burst values. So, for the sake of improving strength design of tubing and casing, this paper deduces the plastic limit pressure of tubing and casing under internal pressure by applying the twin shear unified strength theory. According to the research of the influence rule of yield-to-tensile strength ratio and mechanical properties on the burst strength of tubing and casing, the more precise calculation model of tubing-casing's burst strength has been established with material hardening and intermediate principal stress. Numerical and experimental comparisons show that the new burst strength model is much closer to the real burst values than that of other models. The research results provide an important reference to optimize the tubing and casing design of deep and ultra-deep wells.

Development of K-Basin High-Strength Homogeneous Sludge Simulants and Correlations Between Unconfined Compressive Strength and Shear Strength

Energy Technology Data Exchange (ETDEWEB)

Onishi, Yasuo; Baer, Ellen BK; Chun, Jaehun; Yokuda, Satoru T.; Schmidt, Andrew J.; Sande, Susan; Buchmiller, William C.

2011-02-20

K-Basin sludge will be stored in the Sludge Transport and Storage Containers (STSCs) at an interim storage location on Central Plateau before being treated and packaged for disposal. During the storage period, sludge in the STSCs may consolidate/agglomerate, potentially resulting in high-shear-strength material. The Sludge Treatment Project (STP) plans to use water jets to retrieve K-Basin sludge after the interim storage. STP has identified shear strength to be a key parameter that should be bounded to verify the operability and performance of sludge retrieval systems. Determining the range of sludge shear strength is important to gain high confidence that a water-jet retrieval system can mobilize stored K-Basin sludge from the STSCs. The shear strength measurements will provide a basis for bounding sludge properties for mobilization and erosion. Thus, it is also important to develop potential simulants to investigate these phenomena. Long-term sludge storage tests conducted by Pacific Northwest National Laboratory (PNNL) show that high-uranium-content K-Basin sludge can self-cement and form a strong sludge with a bulk shear strength of up to 65 kPa. Some of this sludge has 'paste' and 'chunks' with shear strengths of approximately 3-5 kPa and 380-770 kPa, respectively. High-uranium-content sludge samples subjected to hydrothermal testing (e.g., 185 C, 10 hours) have been observed to form agglomerates with a shear strength up to 170 kPa. These high values were estimated by measured unconfined compressive strength (UCS) obtained with a pocket penetrometer. Due to its ease of use, it is anticipated that a pocket penetrometer will be used to acquire additional shear strength data from archived K-Basin sludge samples stored at the PNNL Radiochemical Processing Laboratory (RPL) hot cells. It is uncertain whether the pocket penetrometer provides accurate shear strength measurements of the material. To assess the bounding material strength and

Green options for anti-corrosion of high strength concrete incorporating ternary pozzolan materials

Directory of Open Access Journals (Sweden)

Chen Yuan-Yuan

2017-01-01

Full Text Available This paper applied the densified mixture design algorithm(DMDA method by incorporating ternary pozzolans (fly ash, slag and silica fume; mix I and mix II to design high strength concrete (HSC mixtures with w/cm ratios from 0.24 to 0.30. Concrete without pozzolans was used as a control group (mix III, w/c from 0.24 to 0.30, and silica fume (5% was added as a substitute for part of the cement and set as mix IV. Experiments performed compressive strength, four-point resistance meter to measure the conductivity, and rapid chloride ion penetrability tests (ASTM C1202 were assessed the anti-corrosion. The life cycle inventory of LEED suggested by the PCA indicated the green options for cementitious materials. Results showed that mix I and II indicated cement used, CO2 reduction, raw materials and energy consumption all decreased more 50% than mix III, and mix IV was 5% less. The compressive strength and anti-corrosion levels showed that mix I and II were better than mix III and IV, and with ternary pozzolans could enhance the long-term durability (92 days due to a resistivity greater 20 KΩ-cm and a charge passed lower than 2000 Coulombs. HSC with an appropriate design could reduce the carbon footprint and improve the durability.

Strength capability while kneeling.

Science.gov (United States)

Haslegrave, C M; Tracy, M F; Corlett, E N

1997-12-01

Work sometimes has to be carried out kneeling, particularly where jobs are performed in confined spaces as is common for miners, aircraft baggage handlers and maintenance workers. In order to assess the risks in performing forceful tasks under such conditions, data is needed on strength capabilities of kneeling subjects. A study was undertaken to measure isometric strength in single-handed exertions for male subjects and to investigate the effects on this of task layout factors (direction of force exertion, reach distance, height of the workpiece and orientation relative to the subject's sagittal plane). The data has been tabulated to show the degree to which strength may be reduced in different situations and analysis of the task factors showed their influence to be complex with direction of exertion and reach distance having the greatest effect. The results also suggest that exertions are weaker when subjects are kneeling on two knees than when kneeling on one knee, although this needs to be confirmed by direct experimental comparison.

Strength development in concrete with wood ash blended cement and use of soft computing models to predict strength parameters

Directory of Open Access Journals (Sweden)

S. Chowdhury

2015-11-01

Full Text Available In this study, Wood Ash (WA prepared from the uncontrolled burning of the saw dust is evaluated for its suitability as partial cement replacement in conventional concrete. The saw dust has been acquired from a wood polishing unit. The physical, chemical and mineralogical characteristics of WA is presented and analyzed. The strength parameters (compressive strength, split tensile strength and flexural strength of concrete with blended WA cement are evaluated and studied. Two different water-to-binder ratio (0.4 and 0.45 and five different replacement percentages of WA (5%, 10%, 15%, 18% and 20% including control specimens for both water-to-cement ratio is considered. Results of compressive strength, split tensile strength and flexural strength showed that the strength properties of concrete mixture decreased marginally with increase in wood ash contents, but strength increased with later age. The XRD test results and chemical analysis of WA showed that it contains amorphous silica and thus can be used as cement replacing material. Through the analysis of results obtained in this study, it was concluded that WA could be blended with cement without adversely affecting the strength properties of concrete. Also using a new statistical theory of the Support Vector Machine (SVM, strength parameters were predicted by developing a suitable model and as a result, the application of soft computing in structural engineering has been successfully presented in this research paper.

EFFECTS OF CREATINE, GINSENG, AND ASTRAGALUS SUPPLEMENTATION ON STRENGTH, BODY COMPOSITION, MOOD, AND BLOOD LIPIDS DURING STRENGTH-TRAINING IN OLDER ADULTS

Directory of Open Access Journals (Sweden)

Michael E. Rogers

2006-03-01

Full Text Available The effects of supplemental dietary creatine and a botanical extract consisting of ginseng and astragalus were evaluated in 44 adults aged 55-84 years participating in a 12-week strength-training program. Participants consumed creatine only (Cr, creatine plus botanical extract (CrBE, or placebo (PL, and performed bench press, lat pull down, biceps curl, leg press, knee extension, and knee flexion for 3 sets of 8-12 reps on 3 days per week for 12 weeks. The 1-repetition maximum for each exercise, body composition (full-body DEXA, blood lipids, and mood states were evaluated before and after the intervention. Training improved (p < 0.05 strength and lean mass for all groups, however greater gains were observed with Cr and CrBE compared with placebo (but no difference was found between Cr and CrBE. Only CrBE improved blood lipids and self-reported vigor, and the CrBE group lost significantly more body fat and gained more bench press strength than Cr. These results indicate that strength and lean mass gains achieved by older adults participating in a strength training program can be enhanced with creatine supplementation, and that ginseng and astragalus may provide additional health and psychological benefits. However, these herbs do not appear to have an additive effect on strength and lean mass gains during training

Lean mass influences overnight changes in hydration, blood pressure and strength in community-dwelling older women.

Science.gov (United States)

Benton, Melissa J; Schlairet, Maura C

2016-10-01

We evaluated the hypothesis that greater lean mass promotes better overnight hydration, improved postural blood pressure and greater strength. Thirty women, aged 71 ± 0.9 years (mean ± SE), completed one measurement in a euhydrated state and another the following morning after an overnight fast. Measurements included hydration, lean mass, orthostatic blood pressure and strength. Participants were grouped by fat-free mass index (FFMI), with cut-points defined as low (blood pressure. On day 1, women with low FFMI experienced significant postural systolic blood pressure changes from sitting to standing (-11.3 ± 4.0 mmHg, p postural blood pressure and loss of strength that increases the risk for early morning falls.

Global model for the lithospheric strength and effective elastic thickness

Science.gov (United States)

Tesauro, Magdala; Kaban, Mikhail K.; Cloetingh, Sierd A. P. L.

2013-08-01

Global distribution of the strength and effective elastic thickness (Te) of the lithosphere are estimated using physical parameters from recent crustal and lithospheric models. For the Te estimation we apply a new approach, which provides a possibility to take into account variations of Young modulus (E) within the lithosphere. In view of the large uncertainties affecting strength estimates, we evaluate global strength and Te distributions for possible end-member 'hard' (HRM) and a 'soft' (SRM) rheology models of the continental crust. Temperature within the lithosphere has been estimated using a recent tomography model of Ritsema et al. (2011), which has much higher horizontal resolution than previous global models. Most of the strength is localized in the crust for the HRM and in the mantle for the SRM. These results contribute to the long debates on applicability of the "crème brulée" or "jelly-sandwich" model for the lithosphere structure. Changing from the SRM to HRM turns most of the continental areas from the totally decoupled mode to the fully coupled mode of the lithospheric layers. However, in the areas characterized by a high thermal regime and thick crust, the layers remain decoupled even for the HRM. At the same time, for the inner part of the cratons the lithospheric layers are coupled in both models. Therefore, rheological variations lead to large changes in the integrated strength and Te distribution in the regions characterized by intermediate thermal conditions. In these areas temperature uncertainties have a greater effect, since this parameter principally determines rheological behavior. Comparison of the Te estimates for both models with those determined from the flexural loading and spectral analysis shows that the 'hard' rheology is likely applicable for cratonic areas, whereas the 'soft' rheology is more representative for young orogens.

Vascular Function and Handgrip Strength in Rheumatoid Arthritis Patients

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Mahmoud A. Alomari

2012-01-01

Full Text Available Objective. To examine the relationship of handgrip strength with forearm blood flow (BF and vascular resistance (VR in rheumatoid arthritis (RA patients. Methods. Forearm BF at rest (RBF and after upper arm occlusion (RHBF, and handgrip strength were examined in 78 individuals (RA=42 and controls (CT=36. Subsequently, VR at rest (RVR and after occlusion (RHVR were calculated. Results. The patients’ RBF (P=0.02 and RHBF (P=0.0001 were less, whereas RVR (P=0.002 and RHVR (P=0.0001 were greater as compared to the CTs. Similarly, handgrip strength was lower in the RAs (P=0.0001. Finally, handgrip strength was directly associated with RBF (r=0.43; P=0.0001, and RHBF (r=0.5; P=0.0001, and inversely related to RVR (r=-0.3; P=0.009 and RHVR (r=-0.3; P=0.007. Conclusion. The present study uniquely identifies an association between regional measures of forearm blood flow and handgrip strength in patients and healthy control. In addition, this study confirms the presence of vascular and muscle dysfunction in patients with rheumatoid arthritis, as evidenced by lower forearm blood flow indices, at rest and following occlusion, and lower handgrip strength as compared to healthy individuals.

Influence of strength training intensity on subsequent recovery in elderly

DEFF Research Database (Denmark)

da Rosa Orssatto, Lucas Bet; de Moura, Bruno Monteiro; de Souza Bezerra, Ewertton

2018-01-01

Understanding the influence of strength training intensity on subsequent recovery in elderly is important to avoid reductions in physical function during the days following training. Twenty-two elderly were randomized in two groups: G70 (65.9 ± 4.8 years, n = 11) and G95 (66.9 ± 5.1, n = 11...... in elderly depending on the type of physical function and intensity of training. Higher intensity resulted in greater impairment. Exercise prescription in elderly should take this into account, e.g., by gradually increasing intensity during the first months of strength training. These results have relevance...... for elderly who have to be fit for work or other activities in the days following strength training....

The Character Strengths of Class Clowns

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Willibald F. Ruch

2014-09-01

Full Text Available Class clowns traditionally were studied as a type concept and identified via sociometric procedures. In the present study a variable-centered approach was favored and class clown behaviors were studied in the context of character strengths, orientations to happiness and satisfaction with life. A sample of 672 Swiss children and adolescents filled in an 18 item self-report instrument depicting class clown behaviors. A hierarchical model of class clown behaviors was developed distinguishing a general factor and the four positively correlated dimensions of identified as a class clown, comic talent, disruptive rule-breaker, and subversive joker. Analysis of the general factor showed that class clowns were primarily male, and tended to be seen as class clowns by the teacher. Analyses of the 24 character strengths of the VIA-Youth (Park & Peterson, 2006 showed that class clowns were high in humor and leadership, and low in strengths like prudence, self-regulation, modesty, honesty, fairness, perseverance, and love of learning. An inspection of signature strengths revealed that 75% of class clowns had humor as a signature strength. Furthermore, generally class clown behaviors were shown by students indulging in a life of pleasure, but low life of engagement. The four dimensions yielded different character strengths profiles. While all dimensions of class clowns behaviors were low in temperance strengths, the factors identified as the class clown and comic talent were correlated with leadership strengths and the two negative factors (disruptive rule-breaker, subversive joker were low in other directed strengths. The disruptive rule breaking class clown was additionally low in intellectual strengths. While humor predicted life satisfaction, class clowning tended to go along with diminished satisfaction with life. It is concluded that different types of class clowns need to be kept apart and need different attention by teachers.

The character strengths of class clowns.

Science.gov (United States)

Ruch, Willibald; Platt, Tracey; Hofmann, Jennifer

2014-01-01

Class clowns traditionally were studied as a type concept and identified via sociometric procedures. In the present study a variable-centered approach was favored and class clown behaviors were studied in the context of character strengths, orientations to happiness and satisfaction with life. A sample of 672 Swiss children and adolescents filled in an 18 item self-report instrument depicting class clown behaviors. A hierarchical model of class clown behaviors was developed distinguishing a general factor and the four positively correlated dimensions of "identified as a class clown," "comic talent," "disruptive rule-breaker," and "subversive joker." Analysis of the general factor showed that class clowns were primarily male, and tended to be seen as class clowns by the teacher. Analyses of the 24 character strengths of the VIA-Youth (Park and Peterson, 2006) showed that class clowns were high in humor and leadership, and low in strengths like prudence, self-regulation, modesty, honesty, fairness, perseverance, and love of learning. An inspection of signature strengths revealed that 75% of class clowns had humor as a signature strength. Furthermore, class clown behaviors were generally shown by students indulging in a life of pleasure, but low life of engagement. The four dimensions yielded different character strengths profiles. While all dimensions of class clowns behaviors were low in temperance strengths, the factors "identified as the class clown" and "comic talent" were correlated with leadership strengths and the two negative factors ("disruptive rule-breaker," "subversive joker") were low in other directed strengths. The disruptive rule breaking class clown was additionally low in intellectual strengths. While humor predicted life satisfaction, class clowning tended to go along with diminished satisfaction with life. It is concluded that different types of class clowns need to be kept apart and need different attention by teachers.

Investigations on the tensile strength of high performance concrete incorporating silica fume

International Nuclear Information System (INIS)

Santanu Bhanja; Bratish Sengupta

2005-01-01

Though the literature is rich in reporting on silica fume concrete the technical data on tensile strength is quite limited. The present paper is directed towards developing a better understanding on the isolated contribution of silica fume on the tensile strengths of High Performance Concrete. Extensive experimentation was carried out over water-binder ratios ranging from 0.26 to 0.42 and silica fume binder ratios from 0.0 to 0.3. For all the mixes compressive, flexural and split tensile strengths were determined at 28 days. The results of the present investigation indicate that silica fume incorporation results in significant improvements in the tensile strengths of concrete. It is also observed that the optimum replacement percentage, which led to maximization of strength, is not a constant one but depends on the water- cementitious material ratio of the mix. Compared to split tensile strengths, flexural strengths have exhibited greater percentage gains in strength. Increase in split tensile strength beyond 15% silica fume replacement is almost insignificant whereas sizeable gains in flexural tensile strength have occurred even up to 25% replacements. For the present investigation transgranular failure of concrete was observed which indicate that silica fume incorporation results in significant improvements in the strength of both paste and transition zone. (authors)

Water and saliva contamination effect on shear bond strength of brackets bonded with a moisture-tolerant light cure system.

Science.gov (United States)

Vicente, Ascensión; Mena, Ana; Ortiz, Antonio José; Bravo, Luis Alberto

2009-01-01

To evaluate the effects of water and saliva contamination on shear bond strength of brackets bonded with a moisture-tolerant light cure system. Brackets were bonded to 240 bovine lower incisors divided into 12 groups. Four bonding procedures were evaluated, including (1) TSEP/Transbond XT, (2) TMIP/ Transbond XT, (3) TSEP/Transbond PLUS, and (4) TMIP/Transbond PLUS, each under three different bonding conditions: without contamination, with water contamination, and with saliva contamination. Shear bond strength was measured with a universal testing machine. The adhesive remnant on the teeth was quantified with the use of image analyzing equipment. Without contamination, bond strengths for the four procedures were similar (P > .05). TSEP/Tranbond PLUS and TMIP/Transbond PLUS left significantly less adhesive on the teeth after debonding than TSEP/Transbond XT and TMIP/Transbond XT (P .017), although for TMIP/ Transbond XT, both variables showed significant reductions after contamination (P < .017). TSEP/Transbond PLUS, TMIP/Transbond PLUS, and TSEP/Transbond XT showed greater tolerance to wet conditions than was shown by TMIP/Transbond XT.

Development of high strength hot rolled low carbon copper-bearing steel containing nanometer sized carbides

Energy Technology Data Exchange (ETDEWEB)

Phaniraj, M.P. [High Temperature Energy Materials Research Center, Korea Institute of Science and Technology, Seoul 136-791 (Korea, Republic of); Shin, Young-Min [High Temperature Energy Materials Research Center, Korea Institute of Science and Technology, Seoul 136-791 (Korea, Republic of); Department of Materials Science and Engineering, Korea University, Seoul 136-701 (Korea, Republic of); Lee, Joonho [Department of Materials Science and Engineering, Korea University, Seoul 136-701 (Korea, Republic of); Goo, Nam Hoon [Sheet Product Design Group, Hyundai Steel Co., North Industrial Street 1400, 343-823, DangJin 343-823 (Korea, Republic of); Kim, Dong-Ik; Suh, Jin-Yoo; Jung, Woo-Sang [High Temperature Energy Materials Research Center, Korea Institute of Science and Technology, Seoul 136-791 (Korea, Republic of); Shim, Jae-Hyeok, E-mail: jhshim@kist.re.kr [High Temperature Energy Materials Research Center, Korea Institute of Science and Technology, Seoul 136-791 (Korea, Republic of); Choi, In-Suk, E-mail: insukchoi@kist.re.kr [High Temperature Energy Materials Research Center, Korea Institute of Science and Technology, Seoul 136-791 (Korea, Republic of)

2015-05-01

A low carbon ferritic steel was alloyed with Ti, Mo and Cu with the intention of achieving greater increment in strength by multiple precipitate strengthening. The steel is hot rolled and subjected to interrupted cooling to enable precipitation of Ti–Mo carbides and copper. Thermodynamic calculations were carried out to determine equilibrium phase fractions at different temperatures. Microstructure characterization using transmission electron microscopy and composition analysis revealed that the steel contains ~5 nm size precipitates of (Ti,Mo)C. Precipitation kinetics calculations using MatCalc software showed that mainly body centered cubic copper precipitates of size < 5nm form under the cooling conditions in the present study. The steel has the high tensile strength of 853 MPa and good ductility. The yield strength increases by 420 MPa, which is more than that achieved in hot rolled low carbon ferritic steels with only copper precipitates or only carbide precipitates. The precipitation and strengthening contribution of copper and (Ti,Mo)C precipitates and their effect on the work hardening behavior is discussed.

Predicting hand function in older adults: evaluations of grip strength, arm curl strength, and manual dexterity.

Science.gov (United States)

Liu, Chiung-Ju; Marie, Deana; Fredrick, Aaron; Bertram, Jessica; Utley, Kristen; Fess, Elaine Ewing

2017-08-01

Hand function is critical for independence in activities of daily living for older adults. The purpose of this study was to examine how grip strength, arm curl strength, and manual dexterous coordination contributed to time-based versus self-report assessment of hand function in community-dwelling older adults. Adults aged ≥60 years without low vision or neurological disorders were recruited. Purdue Pegboard Test, Jamar hand dynamometer, 30-second arm curl test, Jebsen-Taylor Hand Function Test, and the Late-Life Function and Disability Instrument were administered to assess manual dexterous coordination, grip strength, arm curl strength, time-based hand function, and self-report of hand function, respectively. Eighty-four adults (mean age = 72 years) completed the study. Hierarchical multiple regressions show that older adults with better arm curl strength (β = -.25, p function test. In comparison, older adults with better grip strength (β = .40, p function. The relationship between grip strength and hand function may be test-specific. Grip strength becomes a significant factor when the test requires grip strength to successfully complete the test tasks. Arm curl strength independently contributed to hand function in both time-based and self-report assessments, indicating that strength of extrinsic muscles of the hand are essential for hand function.

Compressive strength of concrete and mortar containing fly ash

Science.gov (United States)

Liskowitz, John W.; Wecharatana, Methi; Jaturapitakkul, Chai; Cerkanowicz, deceased, Anthony E.

1997-01-01

The present invention relates to concrete, mortar and other hardenable mixtures comprising cement and fly ash for use in construction. The invention includes a method for predicting the compressive strength of such a hardenable mixture, which is very important for planning a project. The invention also relates to hardenable mixtures comprising cement and fly ash which can achieve greater compressive strength than hardenable mixtures containing only concrete over the time period relevant for construction. In a specific embodiment, a formula is provided that accurately predicts compressive strength of concrete containing fly ash out to 180 days. In other specific examples, concrete and mortar containing about 15% to 25% fly ash as a replacement for cement, which are capable of meeting design specifications required for building and highway construction, are provided. Such materials can thus significantly reduce construction costs.

Motor development in individuals with congenital adrenal hyperplasia: strength, targeting, and fine motor skill.

Science.gov (United States)

Collaer, Marcia L; Brook, Charles G D; Conway, Gerard S; Hindmarsh, Peter C; Hines, Melissa

2009-02-01

This study investigated early androgen influence on the development of human motor and visuomotor characteristics. Participants, ages 12-45 years, were individuals with congenital adrenal hyperplasia (CAH), a disorder causing increased adrenal androgen production before birth (40 females, 29 males) and their unaffected relatives (29 females, 30 males). We investigated grip strength and visuomotor targeting tasks on which males generally outperform females, and fine motor pegboard tasks on which females generally outperform males. Physical characteristics (height and weight) were measured to explore whether body parameters could explain differences in motor skills. Females with CAH were stronger and showed better targeting than unaffected females and showed reduced fine visuomotor skill on one pegboard measure, with no difference on the other. Males with CAH were weaker than unaffected males in grip strength but did not differ on the targeting or pegboard measures. Correction for body size could not explain the findings for females, but suggests that the reduced strength of males with CAH may relate to their smaller stature. Further, the targeting advantage in females with CAH persisted following adjustment for their greater strength. Results in females support the hypothesis that androgen may masculinize, or promote, certain motor characteristics at which males excel, and contribute to defeminization of certain fine motor characteristics at which females excel. Thus, these data suggest that organizational effects of androgens on behavior during prenatal life may extend to motor characteristics and may contribute to general sex differences in motor-related behaviors; however, alternative explanations based on activational influences of androgen or altered experiential factors cannot be excluded without further study.

Endogenous hormones, muscle strength, and risk of fall-related fractures in older women.

Science.gov (United States)

Sipilä, Sarianna; Heikkinen, Eino; Cheng, Sulin; Suominen, Harri; Saari, Päivi; Kovanen, Vuokko; Alén, Markku; Rantanen, Taina

2006-01-01

Among older people, fracture-causing fall often leads to health deterioration. The role of endogenous hormone status and muscle strength on fall-related fracture risk is unclear. This study investigates if, after adjustment for bone density, endogenous hormones and muscle strength would predict fall-related limb fracture incidence in older community-dwelling women followed-up over 10 years. As a part of a prospective population-based study, 187 75-year-old women were investigated. Serum estradiol, testosterone, sex hormone binding globulin, and dehydroepiandrosterone sulfate concentrations were analyzed, and isometric muscle strength and bone mineral density were assessed. Fall-related limb fractures were gathered from patient records. Serum estradiol concentration was a significant predictor of fall-related limb fractures. Women with serum estradiol concentrations less than 0.022 nmol/L had a 3-fold risk (relative risk 3.05; 95% confidence interval, 1.26-7.36), and women with estradiol concentrations between 0.022 and 0.066 nmol/L doubled the risk (relative risk 2.24; 95% confidence interval, 0.97-5.19) of fall-related limb fracture compared to the women with estradiol concentrations ()above 0.066 nmol/L. Adjustment for muscle strength and bone mineral density did not materially change the risk estimates. High muscle strength was associated with a low incidence of fall-related limb fractures. This study showed that in 75-year-old women higher serum estradiol concentration and greater muscle strength were independently associated with a low incidence of fall-related limb fractures even after adjustment for bone density. Our results suggest that hormonal status and muscle strength have their own separate mechanisms protecting from fall-related fractures. This finding is of importance in developing preventive strategies, but calls for further study.

Effects of a Six-Week Strength Training Programme on Change of Direction Performance in Youth Team Sport Athletes

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Frank A. Bourgeois

2017-10-01

Full Text Available This study investigated the effects of eccentric phase-emphasis strength training (EPE on unilateral strength and performance in 180- and 45-degree change of direction (COD tasks in rugby union players. A 12-week cross-over design was used to compare the efficacy of resistance training executed with 3 s eccentric duration (EPE, n = 12 against conventional strength training, with no constraints on tempo (CON, n = 6. Players in each condition were categorised as ‘fast’ (FAST or ‘slow’ (SLOW using median trial times from baseline testing. Players recorded greater isometric strength improvements following EPE (ES = −0.54 to 1.80. Whilst these changes were not immediate, players improved in strength following cessation. Improvements in 180-degree COD performance was recorded at all test-points following EPE (ES = −1.32 to −0.15. Improvements in 45-degree COD performance were apparent for FAST following CON (ES = −0.96 to 0.10, but CON was deleterious for SLOW (ES = −0.60 to 1.53. Eccentric phase-emphasis strength training shows potential for sustained strength enhancement. Positive performance changes in COD tasks were category- and condition-specific. The data indicate the greatest improvement occurred at nine weeks following resistance training in these players. Performance benefits may also be specific to COD task, player category, and relative to emphasis on eccentric phase activity.

Situational Strength Cues from Social Sources at Work: Relative Importance and Mediated Effects.

Science.gov (United States)

Alaybek, Balca; Dalal, Reeshad S; Sheng, Zitong; Morris, Alexander G; Tomassetti, Alan J; Holland, Samantha J

2017-01-01

Situational strength is considered one of the most important situational forces at work because it can attenuate the personality-performance relationship. Although organizational scholars have studied the consequences of situational strength, they have paid little attention to its antecedents. To address this gap, the current study focused on situational strength cues from different social sources as antecedents of overall situational strength at work. Specifically, we examined how employees combine situational strength cues emanating from three social sources (i.e., coworkers, the immediate supervisor, and top management). Based on field theory, we hypothesized that the effect of situational strength from coworkers and immediate supervisors (i.e., proximal sources of situational strength) on employees' perceptions of overall situational strength on the job would be greater than the effect of situational strength from the top management (i.e., the distal source of situational strength). We also hypothesized that the effect of situational strength from the distal source would be mediated by the effects of situational strength from the proximal sources. Data from 363 full-time employees were collected at two time points with a cross-lagged panel design. The former hypothesis was supported for one of the two situational strength facets studied. The latter hypothesis was fully supported.

Situational Strength Cues from Social Sources at Work: Relative Importance and Mediated Effects

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Balca Alaybek

2017-09-01

Full Text Available Situational strength is considered one of the most important situational forces at work because it can attenuate the personality–performance relationship. Although organizational scholars have studied the consequences of situational strength, they have paid little attention to its antecedents. To address this gap, the current study focused on situational strength cues from different social sources as antecedents of overall situational strength at work. Specifically, we examined how employees combine situational strength cues emanating from three social sources (i.e., coworkers, the immediate supervisor, and top management. Based on field theory, we hypothesized that the effect of situational strength from coworkers and immediate supervisors (i.e., proximal sources of situational strength on employees' perceptions of overall situational strength on the job would be greater than the effect of situational strength from the top management (i.e., the distal source of situational strength. We also hypothesized that the effect of situational strength from the distal source would be mediated by the effects of situational strength from the proximal sources. Data from 363 full-time employees were collected at two time points with a cross-lagged panel design. The former hypothesis was supported for one of the two situational strength facets studied. The latter hypothesis was fully supported.

Effects of contract-relax vs static stretching on stretch-induced strength loss and length-tension relationship

DEFF Research Database (Denmark)

Balle, S S; Magnusson, S P; McHugh, M P

2015-01-01

The purpose of this study was to determine the acute effects of contract-relax stretching (CRS) vs static stretching (SS) on strength loss and the length-tension relationship. We hypothesized that there would be a greater muscle length-specific effect of CRS vs SS. Isometric hamstring strength wa...

Precipitation strengthened high strength, high conductivity Cu-Cr-Nb alloys produced by chill block melt spinning. Final Report Ph.D. Thesis

Science.gov (United States)

Ellis, David L.; Michal, Gary M.

1989-01-01

A series of Cu-based alloys containing 2 to 10 a/o Cr and 1 to 5 a/o Nb were produced by chill block melt spinning (CBMS). The melt spun ribbons were consolidated and hot rolled to sheet to produce a supersaturated Cu-Cr-Nb solid solution from which the high melting point intermetallic compound Cr2Nb could be precipitated to strengthen the Cu matrix. The results show that the materials possess electrical conductivities in excess of 90 percent that of pure Cu at 200 C and above. The strengths of the Cu-Cr-Nb alloys were much greater than Cu, Cu-0.6 Cr, NARloy-A, and NARloy-Z in the as-melt spun condition. The strengths of the consolidated materials were less than Cu-Cr and Cu-Cr-Zr below 500 C and 600 C respectively, but were significantly better above these temperatures. The strengths of the consolidated materials were greater than NARloy-Z, at all temperatures. The GLIDCOP possessed similar strength levels up to 750 C when the strength of the Cu-Cr-Nb alloys begins to degrade. The long term stability of the Cu-Cr-Nb alloys was measured by the microhardness of aged samples and the growth of precipitates. The microhardness measurements indicate that the alloys overage rapidly, but do not suffer much loss in strength between 10 and 100 hours which confirms the results of the electrical resistivity measurements taken during the aging of the alloys at 500 C. The loss in strength from peak strength levels is significant, but the strength remains exceptionally good. Transmission electron microscopy (TEM) of the as-melt spun samples revealed that Cr2Nb precipitates formed in the liquid Cu during the chill block melt spinning, indicating a very strong driving force for the formation of the precipitates. The TEM of the aged and consolidated materials indicates that the precipitates coarsen considerably, but remain in the submicron range.

Modeling of high-strength concrete-filled FRP tube columns under cyclic load

Science.gov (United States)

Ong, Kee-Yen; Ma, Chau-Khun; Apandi, Nazirah Mohd; Awang, Abdullah Zawawi; Omar, Wahid

2018-05-01

The behavior of high-strength concrete (HSC) - filled fiber-reinforced-polymer (FRP) tubes (HSCFFTs) column subjected to cyclic lateral loading is presented in this paper. As the experimental study is costly and time consuming, a finite element analysis (FEA) is chosen for the study. Most of the previous studies have focused on examining the axial load behavior of HSCFFT column instead of seismic behavior. The seismic behavior of HSCFFT columns has been the main interest in the industry. The key objective of this research is to develop a reliable numerical non-linear FEA model to represent the seismic behavior of such column. A FEA model was developed using the Concrete Damaged Plasticity Model (CDPM) available in the finite element software package (ABAQUS). Comparisons between experimental results from previous research and the predicted results were made based on load versus displacement relationships and ultimate strength of the column. The results showed that the column increased in ductility and able to deform to a greater extent with the increase of the FRP confinement ratio. With the increase of confinement ratio, HSCFFT column achieved a higher moment resistance, thus indicated a higher failure strength in the column under cyclic lateral load. It was found that the proposed FEA model can regenerate the experimental results with adequate accuracy.

TEST-RETEST RELIABILITY OF HAND GRIP STRENGTH MEASUREMENT USING A JAMAR HAND DYNAMOMETER IN PATIENTS WITH ACUTE AND CHRONIC CERVICAL RADICULOPATHY

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Ejazi G

2017-12-01

Full Text Available Background: To evaluate the test-retest reliability of Jamar hand held dynamometer for measuring handgrip strength (HGS in patients with acute and chronic cervical radiculopathy and to find out the difference in measurement of the handgrip strength between acute and chronic cervical radiculopathy. Methods: A prospective, observational and non-experimental, the comparative study design was used. A sample of 72 subjects (37 women and 35 men suffering from cervical radiculopathy were divided into two groups i.e., Group A(acute and Group B(chronic, handgrip strength was measured using Jamar hand held dynamometer on two occasions by the same rater with an interval of 7-days. Data collection was based on standard guidelines of American Society of Hand Therapists. Three gripping trials (measured in Kg with patient’s arm in standardized arm position were recorded. The data was analyzed from the mean score obtained from the sample. Result: One-way Analysis of Variance(ANOVA was used to evaluate test-retest reliability and Tukey-Kramer Multiple Comparison Test used to find the difference between handgrip strength among acute and chronic Cervical radiculopathy cases. Greater P-value (>0.05 in both testing session, as well as 95% of the confidence interval, shows the reliability of the instrument and lesser p-value (0.05 in female subjects shows no significant difference in handgrip strength between the two groups. Conclusion: Excellent test-retest reliability for hand grip strength measurement was measured in patients with acute and chronic cervical radiculopathy shows that the equipment could be used as an assessment tool for this patient and significant difference exists among male handgrip strength between acute and chronic cervical radiculopathy cases whereas no difference exists among female handgrip strength between acute and chronic cervical radiculopathy cases.

EFFECTS OF WHOLE BODY VIBRATION ON STRENGTH AND JUMPING PERFORMANCE IN VOLLEYBALL AND BEACH VOLLEYBALL PLAYERS

Science.gov (United States)

Zmijewski, P.; Jimenez-Olmedo, J.M.; Jové-Tossi, M.A.; Martínez-Carbonell, A.; Suárez-Llorca, C.; Andreu-Cabrera, E.

2014-01-01

The primary aim of this study was to examine the effects of 6-week strength training with whole body vibration (WBV) on leg strength and jumping performance in volleyball and beach volleyball players. Twenty-three sub-elite male volleyball (VB; n=12) and beach volleyball players (BVB; n=11) aged 21.2±3.0 years were divided into two groups and subjected to 6 weeks of strength training (three one-hour sessions per week): (I) 12 players (6 VB and 6 BVB players) underwent training with WBV (30-40 Hz, 1.7-2.5 mm, 3.0-5.7 g), and (II) 11 players (6 VB and 5 BVB players) underwent traditional strength training. Squat jump (SJ) and countermovement squat jump (CMJ) measurements by the Ergo Tester contact platform and maximum leg press test (1RM) were conducted. Three-factor (2 time x 2 WBV use x 2 discipline) analysis of variance for SJ, CMJ and 1RM revealed a significant time main effect (pvolleyball and beach volleyball players increases leg strength more and leads to greater improvement in jump performance than traditional strength training, but greater improvements can be expected in beach volleyball players than in volleyball players. PMID:25187676

Influence of initial imperfections on ultimate strength of spherical shells

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Chang-Li Yu

2017-09-01

Full Text Available Comprehensive consideration regarding influence mechanisms of initial imperfections on ultimate strength of spherical shells is taken to satisfy requirement of deep-sea structural design. The feasibility of innovative numerical procedure that combines welding simulation and non-linear buckling analysis is verified by a good agreement to experimental and theoretical results. Spherical shells with a series of wall thicknesses to radius ratios are studied. Residual stress and deformations from welding process are investigated separately. Variant influence mechanisms are discovered. Residual stress is demonstrated to be influential to stress field and buckling behavior but not to the ultimate strength. Deformations are proved to have a significant impact on ultimate strength. When central angles are less than critical value, concave magnitudes reduce ultimate strengths linearly. However, deformations with central angles above critical value are of much greater harm. Less imperfection susceptibility is found in spherical shells with larger wall thicknesses to radius ratios.

African American therapists working with African American families: an exploration of the strengths perspective in treatment.

Science.gov (United States)

Bell-Tolliver, LaVerne; Burgess, Ruby; Brock, Linda J

2009-07-01

With the exception of Hill's (1971, 1999) work, historically much of the literature on African American families has focused more on pathology than strengths. This study used interviews with 30 African American psychotherapists, self-identified as employing a strengths perspective with African American families, to investigate which strengths they identified in the families and how they use those strengths in therapy. Themes emerging from data analysis confirmed the continued importance of the five strengths Hill noted. In addition, two new strengths were identified by the participants: a willingness of a greater number of families to seek therapy, and the importance of family structure. Strategies used in engaging the families in therapy and practice implications for family therapists are discussed.

Leg strength or velocity of movement: which is more influential on the balance of mobility limited elders?

Science.gov (United States)

Mayson, Douglas J; Kiely, Dan K; LaRose, Sharon I; Bean, Jonathan F

2008-12-01

To determine which component of leg power (maximal limb strength or limb velocity) is more influential on balance performance in mobility limited elders. In this cross-sectional analysis we evaluated 138 community-dwelling older adults with mobility limitation. Balance was measured using the Unipedal Stance Test, the Berg Balance Test (BERG), the Dynamic Gait Index, and the performance-oriented mobility assessment. We measured one repetition maximum strength and power at 40% one repetition maximum strength, from which velocity was calculated. The associations between maximal estimated leg strength and velocity with balance performance were examined using separate multivariate logistic regression models. Strength was found to be associated [odds ratio of 1.06 (95% confidence interval, 1.01-1.11)] with performance on the Unipedal Stance Test, whereas velocity showed no statistically significant association. In contrast, velocity was consistently associated with performance on all composite measures of balance (BERG 14.23 [1.84-109.72], performance-oriented mobility assessment 33.92 [3.69-312.03], and Dynamic Gait Index 35.80 [4.77-268.71]). Strength was only associated with the BERG 1.08 (1.01-1.14). Higher leg press velocity is associated with better performance on the BERG, performance-oriented mobility assessment, and Dynamic Gait Index, whereas greater leg strength is associated with better performance on the Unipedal Stance Test and the BERG. These findings are likely related to the intrinsic qualities of each test and emphasize the relevance of limb velocity.

Body Build and the Level of Development of Muscle Strength Among Male Jiu-Jitsu Competitors and Strength-Trained Adults

Directory of Open Access Journals (Sweden)

Pietraszewska Jadwiga

2014-09-01

Full Text Available Purpose. The aim of the present study was to assess the morpho-functional characteristics of male jiu-jitsu practitioners against a sample of strength-trained university students. Methods. The all-male research sample included 49 jiu-jitsu competitors and 30 university students actively involved in strength training. Measures of body mass and height, lower extremity length, sitting height, arm span, trunk width, skeletal breadths, circumferences and skinfold thicknesses of the trunk and extremities were collected. Body tissue composition was assessed using bioelectrical impedance analysis. Somatotype was classified according to the anthropometric method of Heath and Carter. Participants also performed three motor tests composed of the standing long jump, flexed arm hang, and sit-ups and two dynamometer tests measuring handgrip and back muscle strength. Differences between the measured characteristics in both samples were analyzed using Student’s t test. Pearson’s correlation coefficient was used to the determine the relationships between the morphological characteristics and the results of the motor tests. Results. The jiu-jitsu sample was slightly smaller than the strength-training students. In contrast, body mass was almost identical in both groups. The remaining length, height, and skinfold characteristics also did not differ significantly between the groups. Only hip breadth was significantly larger in the jiu-jitsu sample. No between-group differences were noted in the levels of endomorphy, mesomorphy, and ectomorphy. The composite somatotype of the jiu-jitsu athletes (2.1-5.8-2.0 was very similar to that of the strength-trained students (2.1-5.9-2.4. Statistically significant differences were observed in the tests assessing muscle strength. Handgrip and back muscle strength was greater in the strength-training students, whereas the jiu-jitsu athletes performed better in all three motor tests. Conclusions. The minor morphological

Isokinetic profile of elbow flexion and extension strength in elite junior tennis players.

Science.gov (United States)

Ellenbecker, Todd S; Roetert, E Paul

2003-02-01

Descriptive study. To determine whether bilateral differences exist in concentric elbow flexion and extension strength in elite junior tennis players. The repetitive nature of tennis frequently produces upper extremity overuse injuries. Prior research has identified tennis-specific strength adaptation in the dominant shoulder and distal upper extremity musculature of elite players. No previous study has addressed elbow flexion and extension strength. Thirty-eight elite junior tennis players were bilaterally tested for concentric elbow flexion and extension muscle performance on a Cybex 6000 isokinetic dynamometer at 90 degrees/s, 210 degrees/s, and 300 degrees/s. Repeated-measures ANOVAs were used to test for differences between extremities, muscle groups, and speed. Significantly greater (Pelbow extension peak torque values were measured at 90 degrees/s, 210 degrees/s, and 300 degrees/s for males. Significantly greater (Pelbow flexion muscular performance in males and for elbow flexion or extension peak torque and single-repetition work values in females. No significant difference between extremities was measured in elbow flexion/extension strength ratios in females and significant differences between extremities in this ratio were only present at 210 degrees/s in males (Pelbow in male elite junior tennis players but not females. These data have ramifications for clinicians rehabilitating upper extremity injuries in patients from this population.

Bond strength and microleakage of current dentin adhesives.

Science.gov (United States)

Fortin, D; Swift, E J; Denehy, G E; Reinhardt, J W

1994-07-01

The purpose of this in vitro study was to evaluate shear bond strengths and microleakage of seven current-generation dentin adhesive systems. Standard box-type Class V cavity preparations were made at the cemento-enamel junction on the buccal surfaces of eighty extracted human molars. These preparations were restored using a microfill composite following application of either All-Bond 2 (Bisco), Clearfil Liner Bond (Kuraray), Gluma 2000 (Miles), Imperva Bond (Shofu), OptiBond (Kerr), Prisma Universal Bond 3 (Caulk), Scotchbond Multi-Purpose (3M), or Scotchbond Dual-Cure (3M) (control). Lingual dentin of these same teeth was exposed and polished to 600-grit. Adhesives were applied and composite was bonded to the dentin using a gelatin capsule technique. Specimens were thermocycled 500 times. Shear bond strengths were determined using a universal testing machine, and microleakage was evaluated using a standard silver nitrate staining technique. Clearfill Liner Bond and OptiBond, adhesive systems that include low-viscosity, low-modulus intermediate resins, had the highest shear bond strengths (13.3 +/- 2.3 MPa and 12.9 +/- 1.5 MPa, respectively). Along with Prisma Universal Bond 3, they also had the least microleakage at dentin margins of Class V restorations. No statistically significant correlation between shear bond strength and microleakage was observed in this study. Adhesive systems that include a low-viscosity intermediate resin produced the high bond strengths and low microleakage. Similarly, two materials with bond strengths in the intermediate range had significantly increased microleakage, and one material with a bond strength in the low end of the spectrum exhibited microleakage that was statistically greater. Thus, despite the lack of statistical correlation, there were observable trends.

Asymptotic strength of thermal pulses in the helium shell burning

Energy Technology Data Exchange (ETDEWEB)

Fujimoto, M Y [Niigata Univ. (Japan); Sugimoto, D

1979-03-01

Secular growth in the strength of the recurrent thermal pulses of helium shell burning is discussed for the purpose of determining its asymptotic strength. It is shown that the pulse grows stronger if the helium zone has been cooled more before the initiation of the pulse. The secular growth of the pulse is related with the increasing degree of cooling. Thermal pulses are computed for an initial model corresponding to the maximum possible cooling, i.e., for a model in which the steady-state entropy distribution was realized in the helium zone. Such thermal pulses are shown to give an upper bound to the asymptotic strength, which is close enough to the asymptotic strength itself for relatively large core masses. Numerical results are given for the core mass of 1.07 M sub(sun), for which the asymptotic strength is found to be 9 x 10/sup 6/ L sub(sun). Thermal pulses are also computed for an initial model which has been cooled artificially more than the steady-state model. The first pulse results in a much greater strength than in the normal model, but a later pulse approaches the normal asymptotic value. Such models are also discussed in relation to the shell flashes on accreting white dwarfs.

Effects of weightlifting vs. kettlebell training on vertical jump, strength, and body composition.

Science.gov (United States)

Otto, William H; Coburn, Jared W; Brown, Lee E; Spiering, Barry A

2012-05-01

Effects of weightlifting vs. kettlebell training on vertical jump, strength, and body composition. J Strength Cond Res 26(5): 1199-1202, 2012-The present study compared the effects of 6 weeks of weightlifting plus traditional heavy resistance training exercises vs. kettlebell training on strength, power, and anthropometric measures. Thirty healthy men were randomly assigned to 1 of 2 groups: (a) weightlifting (n = 13; mean ± SD: age, 22.92 ± 1.98 years; body mass, 80.57 ± 12.99 kg; height, 174.56 ± 5.80 cm) or (b) kettlebell (n = 17; mean ± SD: age, 22.76 ± 1.86 years; body mass, 78.99 ± 10.68 kg; height, 176.79 ± 5.08 cm) and trained 2 times a week for 6 weeks. A linear periodization model was used for training; at weeks 1-3 volume was 3 × 6 (kettlebell swings or high pull), 4 × 4 (accelerated swings or power clean), and 4 × 6 (goblet squats or back squats), respectively, and the volume increased during weeks 4-6 to 4 × 6, 6 × 4, and 4 × 6, respectively. Participants were assessed for height (in centimeters), body mass (in kilograms), and body composition (skinfolds). Strength was assessed by the back squat 1 repetition maximum (1RM), whereas power was assessed by the vertical jump and power clean 1RM. The results of this study indicated that short-term weightlifting and kettlebell training were effective in increasing strength and power. However, the gain in strength using weightlifting movements was greater than that during kettlebell training. Neither method of training led to significant changes in any of the anthropometric measures. In conclusion, 6 weeks of weightlifting induced significantly greater improvements in strength compared with kettlebell training. No between-group differences existed for the vertical jump or body composition.

Push-off tests and strength evaluation of joints combining shrink fitting with bonding

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Yoneno, Masahiro; Sawa, Toshiyuki; Shimotakahara, Ken; Motegi, Yoichi

1997-03-01

Shrink fitted joints have been used in mechanical structures. Recently, joints combining shrink fitting with anaerobic adhesives bonded between the shrink fitted surfaces have been appeared in order to increase the joint strength. In this paper, push-off test was carried out on strength of joints combining shrink fitting with bonding by material testing machine. In addition, the push-off strength of shrink fitting joints without an anaerobic adhesive was also measured. In the experiments, the effects of the shrinking allowance and the outer diameter of the rings on the joint strength are examined. The interface stress distribution in bonded shrink fitted joints subjected to a push-off load is analyzed using axisymmetrical theory of elasticity as a four-body contact problem. Using the interface stress distribution, a method for estimating joint strength is proposed. The experimental results are in a fairly good agreement with the numerical results. It is found that the strength of combination joints is greater than that of shrink fitted joints.

Examination of factors affecting gait properties in healthy older adults: focusing on knee extension strength, visual acuity, and knee joint pain.

Science.gov (United States)

Demura, Tomohiro; Demura, Shin-ichi; Uchiyama, Masanobu; Sugiura, Hiroki

2014-01-01

Gait properties change with age because of a decrease in lower limb strength and visual acuity or knee joint disorders. Gait changes commonly result from these combined factors. This study aimed to examine the effects of knee extension strength, visual acuity, and knee joint pain on gait properties of for 181 healthy female older adults (age: 76.1 (5.7) years). Walking speed, cadence, stance time, swing time, double support time, step length, step width, walking angle, and toe angle were selected as gait parameters. Knee extension strength was measured by isometric dynamometry; and decreased visual acuity and knee joint pain were evaluated by subjective judgment whether or not such factors created a hindrance during walking. Among older adults without vision problems and knee joint pain that affected walking, those with superior knee extension strength had significantly greater walking speed and step length than those with inferior knee extension strength (P pain in both knees showed slower walking speed and longer stance time and double support time. A decrease of knee extension strength and visual acuity and knee joint pain are factors affecting gait in the female older adults. Decreased knee extension strength and knee joint pain mainly affect respective distance and time parameters of the gait.

Improving the Q:H strength ratio in women using plyometric exercises.

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Tsang, Kavin K W; DiPasquale, Angela A

2011-10-01

Plyometric training programs have been implemented in anterior cruciate ligament injury prevention programs. Plyometric exercises are designed to aid in the improvement of muscle strength and neuromuscular control. Our purpose was to examine the effects of plyometric training on lower leg strength in women. Thirty (age = 20.3 ± 1.9 years) recreationally active women were divided into control and experimental groups. The experimental group performed a plyometric training program for 6 weeks, 3 d·wk(-1). All subjects attended 4 testing sessions: before the start of the training program and after weeks 2, 4, and 6. Concentric quadriceps and hamstring strength (dominant leg) was assessed using an isokinetic dynamometer at speeds of 60 and 120°·s(-1). Peak torque, average peak torque, and average power (AvgPower) were measured. The results revealed a significant (p plyometric group than in the control group at testing session 4 and that AvgPower was greater in the plyometric group than in the control group in testing sessions 2-4. Our results indicate that the plyometric training program increased hamstring strength while maintaining quadriceps strength, thereby improving the Q:H strength ratio.

Relationship between thin-film bond strength as measured by a scratch test, and indentation hardness for bonding agents.

Science.gov (United States)

Kusakabe, Shusuke; Rawls, H Ralph; Hotta, Masato

2016-03-01

To evaluate thin-film bond strength between a bonding agent and human dentin, using a scratch test, and the characteristics and accuracy of measurement. One-step bonding agents (BeautiBond; Bond Force; Adper Easy Bond; Clearfil tri-S Bond) and two-step bonding agents (Cleafil SE Bond; FL-Bond II) were investigated in this study. Flat dentin surfaces were prepared for extracted human molars. The dentin surfaces were ground and bonding agents were applied and light cured. The thin-film bond strength test of the specimens was evaluated by the critical load at which the coated bonding agent failed and dentin appeared. The scratch mark sections were then observed under a scanning electron microscope. Indentation hardness was evaluated by the variation in depth under an applied load of 10gf. Data were compared by one-way ANOVA with the Scheffé's post hoc multiple comparison test (pstrength and indentation hardness were analyzed using analysis of correlation and covariance. The thin-film bond strength of two-step bonding agents were found to be significantly higher than that of one-step bonding agents with small standard deviations. Scratch marks consistently showed adhesive failure in the vicinity of the bonding agent/dentin interface. The indentation hardness showed a trend that two-step bonding agents have greater hardness than one-step bonding agents. A moderately significant correlation (r(2)=0.31) was found between thin-film bond strength and indentation hardness. Thin-film bond strength test is a valid and reliable means of evaluating bond strength in the vicinity of the adhesive interface and is more accurate than other methods currently in use. Further, the thin-film bond strength is influenced by the hardness of the cued bonding agent. Copyright © 2015 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

Regulation of assimilate import into sink organs: Update on molecular drivers of sink strength

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Saadia eBihmidine

2013-06-01

Full Text Available Recent developments have altered our view of molecular mechanisms that determine sink strength, defined here as the capacity of non-photosynthetic structures to compete for import of photoassimilates. We review new findings from diverse systems, including stems, seeds, flowers, and fruits. An important advance has been the identification of new transporters and facilitators with major roles in the accumulation and equilibration of sugars at a cellular level. Exactly where each exerts its effect varies among systems. Sugarcane and sweet sorghum stems, for example, both accumulate high levels of sucrose, but may do so via different paths. The distinction is central to strategies for targeted manipulation of sink strength using transporter genes, and shows the importance of system-specific analyses. Another major advance has been the identification of deep hypoxia as a feature of normal grain development. This means that molecular drivers of sink strength in endosperm operate in very low oxygen levels, and under metabolic conditions quite different than previously assumed. Successful enhancement of sink strength has nonetheless been achieved in grains by up-regulating genes for starch biosynthesis. Additionally, our understanding of sink strength is enhanced by awareness of the dual roles played by invertases (INV, not only in sucrose metabolism, but also in production of the hexose sugar signals that regulate cell-cycle and cell-division programs. These contributions of INV to cell expansion and division prove to be vital for establishment of young sinks ranging from flowers to fruit. Since INV genes are themselves sugar-responsive feast genes, they can mediate a feed-forward enhancement of sink strength when assimilates are abundant. Greater overall productivity and yield have thus been attained in key instances, indicating that even broader enhancements may be achievable as we discover the detailed molecular mechanisms that drive sink strength

Muscular Strength Is Associated with Higher Intraocular Pressure in Physically Active Males.

Science.gov (United States)

Vera, Jesús; Jiménez, Raimundo; García-Ramos, Amador; Cárdenas, David

2018-02-01

The positive association between intraocular pressure (IOP) and relative maximum force may have relevance for exercise recommendations when IOP is a concern. The relationship between exercise and IOP has been approached in several studies. However, the influence of muscle function on IOP remains underexplored. This study aimed to determine the relationship between the maximal mechanical capabilities of muscles to generate force, velocity, and power with IOP. Sixty-five physically active males participated in this cross-sectional study. Baseline IOP measures were obtained by rebound tonometry, and participants performed an incremental loading test in the ballistic bench press. Baseline IOP showed a strong positive correlation with relative maximum force (r65 = 0.85, P .05). There is a positive association between greater upper-body power and strength with higher baseline IOP, which might have important implications in the management of ocular health and especially in individuals constantly involved in resistance training programs (e.g., military personnel, weightlifters). The possible protective effect of high fitness level on the acute IOP response to strength exercise needs to be addressed in future studies.

Effects of strength training on blood lipoprotein concentrations in postmenopausal women

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Cleiton Silva Correa

2014-12-01

Full Text Available Strength training is often identified as a contributing factor in prevention of diseases and as a non-pharmacological treatment for metabolic disorders and for control of body mass. Its protective effects and utility for management of disease are amplified in people at risk of diabetes mellitus and dyslipidemias, and cardiovascular diseases (CVD. Recently the benefits of strength training have been used to reduce the risk of these diseases emerging in postmenopausal women, who are at greater risk of CVD than men of the same age. Notwithstanding, little is known about the effects of strength training on metabolism of blood lipoproteins. The objective of this review was to compare the results of articles that have investigated the effects on lipoprotein concentrations of strength training in postmenopausal women. Current articles dealing with the subject, with publication dates from 1979 to 2012 and large numbers of citations by well-known researchers were identified on the Pubmed, Scopus and EBSCO databases. It was concluded that strength training possibly has an action that affects lipoprotein metabolism and concentrations in postmenopausal women.

Do oarsmen have asymmetries in the strength of their back and leg muscles?

Science.gov (United States)

Parkin, S; Nowicky, A V; Rutherford, O M; McGregor, A H

2001-07-01

The aim of this study was to establish whether asymmetry of the strength of the leg and trunk musculature is more prominent in rowers than in controls. Nineteen oarsmen and 20 male controls matched for age, height and body mass performed a series of isokinetic and isometric strength tests on an isokinetic dynamometer. These strength tests focused on the trunk and leg muscles. Comparisons of strength were made between and within groups for right and left symmetry patterns, hamstring: quadriceps ratios, and trunk flexor and extensor ratios. The results revealed no left and right asymmetries in either the knee extensor or flexor strength parameters (including both isometric and isokinetic measures). Knee extensor strength was significantly greater in the rowing population, but knee flexor strength was similar between the two groups. No difference was seen between the groups for the hamstring: quadriceps strength ratio. In the rowing population, stroke side had no influence on leg strength. No differences were observed in the isometric strength of the trunk flexors and extensors between groups, although EMG activity was significantly higher in the rowing population. Patterns of asymmetry of muscle activity were observed between the left and right erector spinae muscles during extension, which was significantly related to rowing side (P low back pain in oarsmen.

Strength of initially virgin martensites at - 196 °C after aging and tempering

Science.gov (United States)

Eldis, George T.; Cohen, Morris

1983-06-01

The compressive strength at -196°C of martensites in Fe-0.26 pct C-24 pct Ni, Fe-0.4 pct C-21 pct Ni, and Fe-0.4 pct C-18 pct Ni-3 pct Mo alloys, all with subzero M temperatures, has been determined in the virgin condition and after one hour at temperatures from -80 to +400 °C. The effects of ausforming (20 pct reduction in area of the austenite by swaging at room temperature prior to the martensitic transformation) were also investigated. For the unausformed martensites, aging at temperatures up to 0 °C results in relatively small increases in strength. Above 0 °C, the age hardening increment increases rapidly, reaching a maximum at 100 °C. Above 100 °C, the strength decreases continuously with increasing tempering temperature except for the molybdenum-containing alloy, which exhibits secondary hardening on tempering at 400 °C. For the ausformed martensites, the response to aging at subzero temperatures is greater than for unausformed material. Strength again passes through a maximum on aging at 100 °C. However, on tempering just above 100 °C, the ausformed materials show a slower rate of softening than the unausformed martensites. The strengthening produced by the ausforming treatment is largest for the Fe-0.4 pct C-18 pct Ni-3 pct Mo alloy, but there is no evidence of carbide precipitation in the deformed austenite to a°Count for this effect of molybdenum.

In vitro comparison of the tensile bond strength of denture adhesives on denture bases.

Science.gov (United States)

Kore, Doris R; Kattadiyil, Mathew T; Hall, Dan B; Bahjri, Khaled

2013-12-01

With several denture adhesives available, it is important for dentists to make appropriate patient recommendations. The purpose of this study was to evaluate the tensile bond strength of denture adhesives on denture base materials at time intervals of up to 24 hours. Fixodent, Super Poligrip, Effergrip, and SeaBond denture adhesives were tested with 3 denture base materials: 2 heat-polymerized (Lucitone 199 and SR Ivocap) and 1 visible-light-polymerized (shade-stable Eclipse). Artificial saliva with mucin was used as a control. Tensile bond strength was tested in accordance with American Dental Association specifications at 5 minutes, 3 hours, 6 hours, 12 hours, and 24 hours after applying the adhesive. Maximum forces before failure were recorded in megapascals (MPa), and the data were subjected to a 2-way analysis of variance (α=.05). All 4 adhesives had greater tensile bond strength than the control. Fixodent, Super Poligrip, and SeaBond had higher tensile bond strength values than Effergrip. All adhesives had the greatest tensile bond strength at 5 minutes and the least at 24 hours. The 3 denture bases produced significantly different results with each adhesive (Padhesives had the greatest tensile bond strength, followed by Ivocap and Eclipse. All 4 adhesives had greater tensile bond strength than the control, and all 4 adhesives were strongest at the 5-minute interval. On all 3 types of denture bases, Effergrip produced significantly lower tensile bond strength, and Fixodent, Super Poligrip, and SeaBond produced significantly higher tensile bond strength. At 24 hours, the adhesive-base combinations with the highest tensile bond strength were Fixodent on Lucitone 199, Fixodent on Eclipse, Fixodent on Ivocap, and Super Poligrip on Ivocap. Copyright © 2013 Editorial Council for the Journal of Prosthetic Dentistry. Published by Mosby, Inc. All rights reserved.

Apparent interfacial shear strength of short-flax-fiber/starch acetate composites

DEFF Research Database (Denmark)

Andersons, J.; Modniks, J.; Joffe, R.

2016-01-01

The paper deals with an indirect industry-friendly method for identification of the interfacial shear strength (IFSS) in a fully bio-based composite. The IFSS of flax fiber/starch acetate is evaluated by a modified Bowyer and Bader method based on an analysis of the stress-strain curve of a short......-fiber-reinforced composite in tension. A shear lag model is developed for the tensile stress-strain response of short-fiber-reinforced composites allowing for an elastic-perfectly plastic stress transfer. Composites with different fiber volume fractions and a variable content of plasticizer have been analyzed. The apparent...... IFSS of flax/starch acetate is within the range of 5.5-20.5 MPa, depending on composition of the material. The IFSS is found to be greater for composites with a higher fiber loading and to decrease with increasing content of plasticizer. The IFSS is equal or greater than the yield strength of the neat...

The Effects of Whole-Body Vibration on the Cross-Transfer of Strength

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Alicia M. Goodwill

2012-01-01

Full Text Available This study investigated whether the use of superimposed whole-body vibration (WBV during cross-education strength training would optimise strength transfer compared to conventional cross-education strength training. Twenty-one healthy, dominant right leg volunteers (21±3 years were allocated to a strength training (ST, m=3, f=4, a strength training with WBV (ST + V, m=3, f=4, or a control group (no training, m=3, f=4. Training groups performed 9 sessions over 3 weeks, involving unilateral squats for the right leg, with or without WBV (35 Hz; 2.5 mm amplitude. All groups underwent dynamic single leg maximum strength testing (1RM and single and paired pulse transcranial magnetic stimulation (TMS prior to and following training. Strength increased in the trained limb for the ST (41%; ES=1.14 and ST + V (55%; ES=1.03 groups, which resulted in a 35% (ES=0.99 strength transfer to the untrained left leg for the ST group and a 52% (ES=0.97 strength transfer to the untrained leg for the ST + V group, when compared to the control group. No differences in strength transfer between training groups were observed (P=0.15. For the untrained leg, no differences in the peak height of recruitment curves or SICI were observed between ST and ST + V groups (P=1.00. Strength training with WBV does not appear to modulate the cross-transfer of strength to a greater magnitude when compared to conventional cross-education strength training.

Estimates of pitch strength for musicians and nonmusicians

Science.gov (United States)

Clarkson, Marsha G.; Zettler, Cynthia M.; Follmer, Michelle J.; Faulk, Margaret; Takagi, Michael J.

2003-04-01

To measure the strength of the pitch of iterated rippled noise (IRN), 19 adults were tested in an operant conditioning procedure. Seven adults had music training and currently played an instrument; 12 adults had no training and did not currently play an instrument. To generate IRN, a 500-ms Gaussian noise stimulus was delayed by 5 or 6 ms (pitches of 200 or 166 Hz) and added to the original for 16 iterations. IRN stimuli having one delay were presented repeatedly. On signal trials the delay changed for 6 s. Stimulus level roved from 63-67 dBA (background of 28 dBA). Adults learned to press a button when the stimulus changed. Testing started with IRN stimuli having 0-dB attenuation (i.e., maximal pitch strength). Stimuli having weaker pitches (i.e., progressively greater attenuation applied to the delayed noise) followed. Strength of pitch was quantified as the maximum attenuation for which pitch was discerned. For each subject, threshold attenuation for pitch strength was extrapolated as the 71% point on a psychometric function depicting percent correct performance as a function of attenuation. Mean thresholds revealed that the pitch percept was similar for both nonmusically trained (18.70 dB) and musically trained adults (18.73 dB).

Focusing on psychiatric patients' strengths: A new vision on mental health care in Iran.

Science.gov (United States)

Zargham-Boroujeni, Ali; Maghsoudi, Jahangir; Oreyzi, Hamid Reza

2015-01-01

Identifying and using the strengths of patients, in practice, is a new territory. Today, the need to educate nurses and psychiatric patients about positive psychology in practice and the importance of understanding and focusing on strengths is clear. However, little is known about the strengths the psychiatric patients use and experience. Thus, this study has been designed and conducted in order to understand how people with psychiatric disorders demonstrate their strengths. In the present study, 13 semi-structured, qualitative interviews with patients and 2 focus groups with nurses were carried out. In addition, a qualitative content analysis was used to identify significant strengths. Based on the results, the four main strengths consisted of: Finding a meaning in daily living, work as enduring strength, entertaining activities, and positive relationship. Patients also reported that health care providers rarely focused on patients' strengths, and experts confirmed these findings. Our findings indicate that patients' own strengths are a pivotal factor in getting through their illness from their perspective. Despite the enduring legacy of pessimism regarding psychiatric patients, these people have a repertoire of strengths. Nurses should, therefore, have a greater focus on eliciting and nourishing psychiatric patients' strengths in their care. It is suggested that the theoretical and practical aspects of patients' strengths be incorporated in nursing school curricula.

Sink strength simulations using the Monte Carlo method: Applied to spherical traps

Science.gov (United States)

Ahlgren, T.; Bukonte, L.

2017-12-01

The sink strength is an important parameter for the mean-field rate equations to simulate temporal changes in the micro-structure of materials. However, there are noteworthy discrepancies between sink strengths obtained by the Monte Carlo and analytical methods. In this study, we show the reasons for these differences. We present the equations to estimate the statistical error for sink strength calculations and show the way to determine the sink strengths for multiple traps. We develop a novel, very fast Monte Carlo method to obtain sink strengths. The results show that, in addition to the well-known sink strength dependence of the trap concentration, trap radius and the total sink strength, the sink strength also depends on the defect diffusion jump length and the total trap volume fraction. Taking these factors into account, allows us to obtain a very accurate analytic expression for the sink strength of spherical traps.

Ripples on spikes show increased phase-amplitude coupling in mesial temporal lobe epilepsy seizure onset zones

Science.gov (United States)

Weiss, Shennan A; Orosz, Iren; Salamon, Noriko; Moy, Stephanie; Wei, Linqing; Van ’t Klooster, Maryse A; Knight, Robert T; Harper, Ronald M; Bragin, Anatol; Fried, Itzhak; Engel, Jerome; Staba, Richard J

2016-01-01

Objective Ripples (80–150 Hz) recorded from clinical macroelectrodes have been shown to be an accurate biomarker of epileptogenic brain tissue. We investigated coupling between epileptiform spike phase and ripple amplitude to better understand the mechanisms that generate this type of pathological ripple (pRipple) event. Methods We quantified phase amplitude coupling (PAC) between epileptiform EEG spike phase and ripple amplitude recorded from intracranial depth macroelectrodes during episodes of sleep in 12 patients with mesial temporal lobe epilepsy. PAC was determined by 1) a phasor transform that corresponds to the strength and rate of ripples coupled with spikes, and a 2) ripple-triggered average to measure the strength, morphology, and spectral frequency of the modulating and modulated signals. Coupling strength was evaluated in relation to recording sites within and outside the seizure onset zone (SOZ). Results Both the phasor transform and ripple-triggered averaging methods showed ripple amplitude was often robustly coupled with epileptiform EEG spike phase. Coupling was more regularly found inside than outside the SOZ, and coupling strength correlated with the likelihood a macroelectrode’s location was within the SOZ (pripples coupled with EEG spikes inside the SOZ to rates of coupled ripples in non-SOZ was greater than the ratio of rates of ripples on spikes detected irrespective of coupling (pripple amplitude (pripple spectral frequency (pripple amplitude. The changes in excitability reflected as epileptiform spikes may also cause clusters of pathologically interconnected bursting neurons to grow and synchronize into aberrantly large neuronal assemblies. PMID:27723936

STRENGTH OF NANOMODIFIED HIGH-STRENGTH LIGHTWEIGHT CONCRETES

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NOZEMTСEV Alexandr Sergeevich

2013-02-01

Full Text Available The paper presents the results of research aimed at development of nanomodified high-strength lightweight concrete for construction. The developed concretes are of low average density and high ultimate compressive strength. It is shown that to produce this type of concrete one need to use hollow glass and aluminosilicate microspheres. To increase the durability of adhesion between cement stone and fine filler the authors offer to use complex nanodimensinal modifier based on iron hydroxide sol and silica sol as a surface nanomodifier for hollow microspheres. It is hypothesized that the proposed modifier has complex effect on the activity of the cement hydration and, at the same time increases bond strength between filler and cement-mineral matrix. The compositions for energy-efficient nanomodified high-strength lightweight concrete which density is 1300…1500 kg/m³ and compressive strength is 40…65 MPa have been developed. The approaches to the design of high-strength lightweight concrete with density of less than 2000 kg/m³ are formulated. It is noted that the proposed concretes possess dense homogeneous structure and moderate mobility. Thus, they allow processing by vibration during production. The economic and practical implications for realization of high-strength lightweight concrete in industrial production have been justified.

Leg Strength or Velocity of Movement Which Is More Influential on the Balance of Mobility Limited Elders?

Science.gov (United States)

Mayson, Douglas J.; Kiely, Dan K.; LaRose, Sharon I.; Bean, Jonathan F.

2009-01-01

Objective To determine which component of leg power (maximal limb strength or limb velocity) is more influential on balance performance in mobility limited elders. Design In this cross-sectional analysis we evaluated 138 community-dwelling older adults with mobility limitation. Balance was measured using the Unipedal Stance Test, the Berg Balance Test (BERG), the Dynamic Gait Index, and the performance-oriented mobility assessment. We measured one repetition maximum strength and power at 40% one repetition maximum strength, from which velocity was calculated. The associations between maximal estimated leg strength and velocity with balance performance were examined using separate multivariate logistic regression models. Results Strength was found to be associated [odds ratio of 1.06 (95% confidence interval, 1.01–1.11)] with performance on the Unipedal Stance Test, whereas velocity showed no statistically significant association. In contrast, velocity was consistently associated with performance on all composite measures of balance [BERG 14.23 (1.84–109.72), performance-oriented mobility assessment 33.92 (3.69–312.03), and Dynamic Gait Index 35.80 (4.77–268.71))]. Strength was only associated with the BERG 1.08 (1.01–1.14). Conclusions Higher leg press velocity is associated with better performance on the BERG, performance-oriented mobility assessment, and Dynamic Gait Index, whereas greater leg strength is associated with better performance on the Unipedal Stance Test and the BERG. These findings are likely related to the intrinsic qualities of each test and emphasize the relevance of limb velocity. PMID:19033758

Familiarization, validity and smallest detectable difference of the isometric squat test in evaluating maximal strength.

Science.gov (United States)

Drake, David; Kennedy, Rodney; Wallace, Eric

2018-02-06

Isometric multi-joint tests are considered reliable and have strong relationships with 1RM performance. However, limited evidence is available for the isometric squat in terms of effects of familiarization and reliability. This study aimed to assess, the effect of familiarization, stability reliability, determine the smallest detectible difference, and the correlation of the isometric squat test with 1RM squat performance. Thirty-six strength-trained participants volunteered to take part in this study. Following three familiarization sessions, test-retest reliability was evaluated with a 48-hour window between each time point. Isometric squat peak, net and relative force were assessed. Results showed three familiarizations were required, isometric squat had a high level of stability reliability and smallest detectible difference of 11% for peak and relative force. Isometric strength at a knee angle of ninety degrees had a strong significant relationship with 1RM squat performance. In conclusion, the isometric squat is a valid test to assess multi-joint strength and can discriminate between strong and weak 1RM squat performance. Changes greater than 11% in peak and relative isometric squat performance should be considered as meaningful in participants who are familiar with the test.

Correlation between compressive strength and ultrasonic pulse velocity of high strength concrete incorporating chopped basalt fibre

Science.gov (United States)

Shafiq, Nasir; Fadhilnuruddin, Muhd; Elshekh, Ali Elheber Ahmed; Fathi, Ahmed

2015-07-01

Ultrasonic pulse velocity (UPV), is considered as the most important test for non-destructive techniques that are used to evaluate the mechanical characteristics of high strength concrete (HSC). The relationship between the compressive strength of HSC containing chopped basalt fibre stands (CBSF) and UPV was investigated. The concrete specimens were prepared using a different ratio of CBSF as internal strengthening materials. The compressive strength measurements were conducted at the sample ages of 3, 7, 28, 56 and 90 days; whilst, the ultrasonic pulse velocity was measured at 28 days. The result of HSC's compressive strength with the chopped basalt fibre did not show any improvement; instead, it was decreased. The UPV of the chopped basalt fibre reinforced concrete has been found to be less than that of the control mix for each addition ratio of the basalt fibre. A relationship plot is gained between the cube compressive strength for HSC and UPV with various amounts of chopped basalt fibres.

Influence of enamel conditioning on the shear bond strength of different adhesives.

Science.gov (United States)

Brauchli, Lorenz; Muscillo, Teodoro; Steineck, Markus; Wichelhaus, Andrea

2010-11-01

Phosphoric acid etching is the gold standard for enamel conditioning. However, it is possible that air abrasion or a combination of air abrasion and etching might result in enhanced adhesion. The aim of this study was to investigate the effect of different enamel conditioning methods on the bond strength of six adhesives. Three different enamel conditioning procedures (phosphoric acid etching, air abrasion, air abrasion + phosphoric acid etching) were evaluated for their influence on the shear bond strength of six different adhesives (Transbond™ XT, Cool-Bond™, Fuji Ortho LC, Ultra Band-Lok, Tetric(®) Flow, Light-Bond™). Each group consisted of 15 specimens. Shear forces were measured with a universal testing machine. The scores of the Adhesive Remnant Index (ARI) were also analyzed. There were no significant differences between phosphoric acid etching and air abrasion + phosphoric acid etching. Air abrasion as a single conditioning technique led to significantly lower shear forces. The ARI scores did not correlate with the shear strengths measured. There were greater variations in shear forces for the different adhesives than for the conditioning techniques. The highest shear forces were found for the conventional composites Transbond™ XT and Cool- Bond™ in combination with conventional etching. Air abrasion alone and in combination with phosphoric acid etching showed no advantages compared with phosphoric acid etching alone and, therefore, cannot be recommended.

Fatigue strength of socket welded pipe joint

International Nuclear Information System (INIS)

Iida, K.; Matsuda, F.; Sato, M.; Higuchi, M.; Nakagawa, A.

1994-01-01

Fully reversed four point bending fatigue tests were carried out of small diameter socket welded joints made of carbon steels. Experimental parameters are pipe diameter, thickness of pipe and socket wall, throat depth and shape of fillet welds, slip-on and diametral gaps in the socket welding, lack of penetration at the root of fillet welds, and peening of fillet welds. In most cases a fatigue crack started from the root of the fillet, but in the case of higher stress amplitude, it tended to start from the toe of fillet. The standard socket welded joint of 50 mm diameter showed relatively low fatigue strength, 46 MPa in stress amplitude at the 10 7 cycles failure life. This value corresponds to about 1/5 of that of the smoothed base metal specimens in axial fatigue. The fatigue strength showed decrease with increasing pipe diameter, and increase with increasing the thickness of pipe and socket wall. The effects of throat depth and shape of fillet welds on fatigue strength were not significant. Contrary to the expectation, the fatigue strength of the socket welded joint without slip-on gap is higher than that of the joint with the normal gap. A lack of penetration at the root deleteriously reduced fatigue strength, showing 14 MPa in stress amplitude at the 10 7 cycles failure life for the 50 mm diameter socket joint. (orig.)

High strength air-dried aerogels

Science.gov (United States)

Coronado, Paul R.; Satcher, Jr., Joe H.

2012-11-06

A method for the preparation of high strength air-dried organic aerogels. The method involves the sol-gel polymerization of organic gel precursors, such as resorcinol with formaldehyde (RF) in aqueous solvents with R/C ratios greater than about 1000 and R/F ratios less than about 1:2.1. Using a procedure analogous to the preparation of resorcinol-formaldehyde (RF) aerogels, this approach generates wet gels that can be air dried at ambient temperatures and pressures. The method significantly reduces the time and/or energy required to produce a dried aerogel compared to conventional methods using either supercritical solvent extraction. The air dried gel exhibits typically less than 5% shrinkage.

A multi-component Zr alloy with comparable strength and Higher plasticity than Zr-based bulk metallic glasses

International Nuclear Information System (INIS)

Liang, S.X.; Yin, L.X.; Ma, M.Z.; Jing, R.; Yu, P.F.; Zhang, Y.F.; Wang, B.A.; Liu, R.P.

2013-01-01

Zirconium (Zr)-based bulk metallic glass possesses the highest potential as a structural material among metallic glasses. Although Zr-based bulk metallic glass exhibits extremely high strength, its potential application has been restricted by a number of issues, such as fragility, small size, difficult fabrication into different shapes and poisonous beryllium content, among others. In this paper, a Zr-based crystal alloy with comparable strength and higher plasticity than Zr-based bulk metallic glass is presented. The proposed Zr-based alloy has a tensile strength greater than 1600 MPa. That value is comparable to the 1500 MPa to 2000 MPa strength of Zr-based bulk metallic glasses (BMGs). The ductility in terms of elongation reached 6.2%; at the same time, the 1400 MPa tensile strength was retained. This phenomenon is not possible for Zr-based BMGs. XRD results show that the proposed ultrahigh-strength Zr-based crystal alloy has two-phase structures: an hcp-structured α phase and a bcc-structured β phase. The forged specimen exhibits a typical basket-weave microstructure, which is characterised by the interlaced plate α phase separated from the β phase matrix. Fine, short bar-shaped α phases precipitated along the original β grain boundary together with ultrafine dot-shaped α phases that presented inside the original β grain when the ageing temperature was between 500 °C and 525 °C. As the ageing temperature increased, the dot-shaped α phase grew into plate shapes, decreasing the material's strength and increasing its plasticity. The ultrafine dot-shaped and short bar-shaped α phases in the original β phase matrix are the main strengthening mechanisms of the ultrahigh-strength Zr-based crystal alloy.

Imaging Shear Strength Along Subduction Faults

Science.gov (United States)

Bletery, Quentin; Thomas, Amanda M.; Rempel, Alan W.; Hardebeck, Jeanne L.

2017-11-01

Subduction faults accumulate stress during long periods of time and release this stress suddenly, during earthquakes, when it reaches a threshold. This threshold, the shear strength, controls the occurrence and magnitude of earthquakes. We consider a 3-D model to derive an analytical expression for how the shear strength depends on the fault geometry, the convergence obliquity, frictional properties, and the stress field orientation. We then use estimates of these different parameters in Japan to infer the distribution of shear strength along a subduction fault. We show that the 2011 Mw9.0 Tohoku earthquake ruptured a fault portion characterized by unusually small variations in static shear strength. This observation is consistent with the hypothesis that large earthquakes preferentially rupture regions with relatively homogeneous shear strength. With increasing constraints on the different parameters at play, our approach could, in the future, help identify favorable locations for large earthquakes.

Imaging shear strength along subduction faults

Science.gov (United States)

Bletery, Quentin; Thomas, Amanda M.; Rempel, Alan W.; Hardebeck, Jeanne L.

2017-01-01

Subduction faults accumulate stress during long periods of time and release this stress suddenly, during earthquakes, when it reaches a threshold. This threshold, the shear strength, controls the occurrence and magnitude of earthquakes. We consider a 3-D model to derive an analytical expression for how the shear strength depends on the fault geometry, the convergence obliquity, frictional properties, and the stress field orientation. We then use estimates of these different parameters in Japan to infer the distribution of shear strength along a subduction fault. We show that the 2011 Mw9.0 Tohoku earthquake ruptured a fault portion characterized by unusually small variations in static shear strength. This observation is consistent with the hypothesis that large earthquakes preferentially rupture regions with relatively homogeneous shear strength. With increasing constraints on the different parameters at play, our approach could, in the future, help identify favorable locations for large earthquakes.

Does change in isolated lumbar extensor muscle function correlate with good clinical outcome? A secondary analysis of data on change in isolated lumbar extension strength, pain, and disability in chronic low back pain.

Science.gov (United States)

Steele, James; Fisher, James; Perrin, Craig; Conway, Rebecca; Bruce-Low, Stewart; Smith, Dave

2018-01-12

Secondary analysis of data from studies utilising isolated lumbar extension exercise interventions for correlations among changes in isolated lumbar extension strength, pain, and disability. Studies reporting isolated lumbar extension strength changes were examined for inclusion criteria including: (1) participants with chronic low back pain, (2) intervention ≥ four weeks including isolated lumbar extension exercise, (3) outcome measures including isolated lumbar extension strength, pain (Visual Analogue Scale), and disability (Oswestry Disability Index). Six studies encompassing 281 participants were included. Correlations among change in isolated lumbar extension strength, pain, and disability. Participants were grouped as "met" or "not met" based on minimal clinically important changes and between groups comparisons conducted. Isolated lumbar extension strength and Visual Analogue Scale pooled analysis showed significant weak to moderate correlations (r = -0.391 to -0.539, all p Disability Index pooled analysis showed significant weak correlations (r = -0.349 to -0.470, all p disability, isolated lumbar extension strength changes were greater for those "met" compared with those "not met" (p disability. This study shows significant correlations between increases in isolated lumbar extension strength and reductions in pain and disability. Strengthening of the lumbar extensor musculature could be considered an important target for exercise interventions.

Measuring Relative Coupling Strength in Circadian Systems.

Science.gov (United States)

Schmal, Christoph; Herzog, Erik D; Herzel, Hanspeter

2018-02-01

Modern imaging techniques allow the monitoring of circadian rhythms of single cells. Coupling between these single cellular circadian oscillators can generate coherent periodic signals on the tissue level that subsequently orchestrate physiological outputs. The strength of coupling in such systems of oscillators is often unclear. In particular, effects on coupling strength by varying cell densities, by knockouts, and by inhibitor applications are debated. In this study, we suggest to quantify the relative coupling strength via analyzing period, phase, and amplitude distributions in ensembles of individual circadian oscillators. Simulations of different oscillator networks show that period and phase distributions become narrower with increasing coupling strength. Moreover, amplitudes can increase due to resonance effects. Variances of periods and phases decay monotonically with coupling strength, and can serve therefore as measures of relative coupling strength. Our theoretical predictions are confirmed by studying recently published experimental data from PERIOD2 expression in slices of the suprachiasmatic nucleus during and after the application of tetrodotoxin (TTX). On analyzing the corresponding period, phase, and amplitude distributions, we can show that treatment with TTX can be associated with a reduced coupling strength in the system of coupled oscillators. Analysis of an oscillator network derived directly from the data confirms our conclusions. We suggest that our approach is also applicable to quantify coupling in fibroblast cultures and hepatocyte networks, and for social synchronization of circadian rhythmicity in rodents, flies, and bees.

Paranoid individuals with schizophrenia show greater social cognitive bias and worse social functioning than non-paranoid individuals with schizophrenia

OpenAIRE

Amy E. Pinkham; Philip D. Harvey; David L. Penn

2016-01-01

Paranoia is a common symptom of schizophrenia that may be related to how individuals process and respond to social stimuli. Previous investigations support a link between increased paranoia and greater social cognitive impairments, but these studies have been limited to single domains of social cognition, and no studies have examined how paranoia may influence functional outcome. Data from 147 individuals with schizophrenia were used to examine whether actively paranoid and non-paranoid indiv...

Is strength-training frequency a key factor to develop performance adaptations in young elite soccer players?

Science.gov (United States)

Otero-Esquina, Carlos; de Hoyo Lora, Moisés; Gonzalo-Skok, Óliver; Domínguez-Cobo, Sergio; Sánchez, Hugo

2017-11-01

The aim of this study was to analyse the effects of a combined strength-training programme (full-back squat, YoYo TM leg curl, plyometrics and sled towing exercises) on performance in elite young soccer players and to examine the effects when this training programme was performed one or two days per week. Thirty-six male soccer players (U-17 to U-19) were recruited and assigned to experimental groups (EXP1: 1 s w -1 ; EXP2: 2 s w -1 ) or a control group (CON). Performance was assessed through a countermovement jump (CMJ) test (relative peak power [CMJ PP ] and CMJ height [CMJ H ]), a 20-m linear sprint test with split-times at 10-m, and a change of direction test (V-cut test) 1 week before starting the training programme and also 1 week after performing such training programme. Within-group analysis showed substantial improvements in CMJ variables (ES: 0.39-0.81) and COD (ES: 0.70 and 0.76) in EXP1 and EXP2, while EXP2 also showed substantial enhancements in all linear sprinting tests (ES: 0.43-0.52). Between-group analysis showed substantially greater improvements in CMJ variables (ES: 0.39-0.68) in experimental groups in comparison to CON. Furthermore, EXP2 achieved a substantial better performance in 20-m (ES: 0.48-0.64) than EXP1 and CON. Finally, EXP2 also showed greater enhancements in 10-m (ES: 0.50) and V-cut test (ES: 0.52) than EXP1. In conclusion, the combined strength-training programme improved jumping ability, independently of training frequency, though the achievement of two sessions per week also enhanced sprinting abilities (linear and COD) in young soccer players.

Effect of friction stir lap welding conditions on joint strength of aluminium alloy 6060

International Nuclear Information System (INIS)

Yazdanian, S; Chen, Z W

2009-01-01

Strength of lap joints made by friction stir welding (FSW) depends strongly on how material flows forming the weld nugget zone during FSW and also on how the joint is loaded during testing. Understanding of this processing-property relationship is currently inadequate. In this study, the effects of pin length, welding speed and rotation rate on weld strength using aluminium alloy 6060 were investigated. It has been found that the pin length needed to be slightly greater than the thickness of the sheet for an adequate joint to be established. However, further increase in pin length did not benefit the joint strength. The major factor affecting joint strength has been found to be the rotation speed. An increase in rotation speed resulted in lowering the joint strength. Various modes of fracture have been observed and these modes relate to the degree of hooking and softening. Explanation of how the speed values relate to heat input and material flow and then to the joint strength is given.

Strength Testing in Motor Neuron Diseases.

Science.gov (United States)

Shefner, Jeremy M

2017-01-01

Loss of muscle strength is a cardinal feature of all motor neuron diseases. Functional loss over time, including respiratory dysfunction, inability to ambulate, loss of ability to perform activities of daily living, and others are due, in large part, to decline in strength. Thus, the accurate measurement of limb muscle strength is essential in therapeutic trials to best understand the impact of therapy on vital function. While qualitative strength measurements show declines over time, the lack of reproducibility and linearity of measurement make qualitative techniques inadequate. A variety of quantitative measures have been developed; all have both positive attributes and limitations. However, with careful training and reliability testing, quantitative measures have proven to be reliable and sensitive indicators of both disease progression and the impact of experimental therapy. Quantitative strength measurements have demonstrated potentially important therapeutic effects in both amyotrophic lateral sclerosis and spinobulbar muscular atrophy, and have been shown feasible in children with spinal muscular atrophy. The spectrum of both qualitative and quantitative strength measurements are reviewed and their utility examined in this review.

Strength functions for fragmented doorway states

International Nuclear Information System (INIS)

MacDonald, W.M.

1980-01-01

Coupling a strongly excited ''doorway state'' to weak ''hallway states'' distributes its strength into micro-resonances seen in differential cross sections taken with very good energy resolution. The distribution of strength is shown to be revealed by reduced widths of the K-matrix rather than by the imaginary part of poles of the S-matrix. Different strength functions (SF) constructed by averaging the K-matrix widths are then investigated to determine their dependences on energy and on parameters related to averages of microscopic matrix elements. A new sum rule on the integrated strength of these SF is derived and used to show that different averaging procedures actually distribute the strength differently. Finally, it is shown that the discontinuous summed strength defines spreading parameters for the doorway state only in strong coupling, where it approximates the idefinite integral of the continuous SF of MacDonald-Mekjian-Kerman-De Toledo Piza. A new method of ''parametric continuation'' is used to relate a discontinuous sliding box-average, or a finite sum, of discrete terms to a continous function

Testosterone Replacement, Muscle Strength, and Physical Function

Directory of Open Access Journals (Sweden)

You-Seon Nam

2018-05-01

Full Text Available Muscle strength and physical function decrease in older men, as do testosterone levels. Nonetheless, the effects of testosterone replacement therapy on muscle strength and physical function remain inconclusive and equivocal. We conducted a rapid systematic review, the results of which showed that testosterone replacement does not affect muscle strength (measured by hand grip strength and leg muscle strength, although it may increase physical function (measured by the 6-minute walk test, Physical Activity Scale for the Elderly score, and other physical performance tests. However, most of the studies were conducted in the United States or Europe and did not include participants from Asian or other ethnic backgrounds; therefore, further studies are needed to evaluate the effects of testosterone replacement in a broader population.

Muscle Strength Is a Poor Screening Test for Predicting Lower Extremity Injuries in Professional Male Soccer Players: A 2-Year Prospective Cohort Study.

Science.gov (United States)

Bakken, Arnhild; Targett, Stephen; Bere, Tone; Eirale, Cristiano; Farooq, Abdulaziz; Mosler, Andrea B; Tol, Johannes L; Whiteley, Rod; Khan, Karim M; Bahr, Roald

2018-03-01

Lower extremity muscle strength tests are commonly used to screen for injury risk in professional soccer. However, there is limited evidence on the ability of such tests in predicting future injuries. To examine the association between hip and thigh muscle strength and the risk of lower extremity injuries in professional male soccer players. Case-control study; Level of evidence, 3. Professional male soccer players from 14 teams in Qatar underwent a comprehensive strength assessment at the beginning of the 2013/2014 and 2014/2015 seasons. Testing consisted of concentric and eccentric quadriceps and hamstring isokinetic peak torques, eccentric hip adduction and abduction forces, and bilateral isometric adductor force (squeeze test at 45°). Time-loss injuries and exposure in training and matches were registered prospectively by club medical staff throughout each season. Univariate and multivariate Cox regression analyses were used to calculate hazard ratios (HRs) with 95% CIs. In total, 369 players completed all strength tests and had registered injury and exposure data. Of these, 206 players (55.8%) suffered 538 lower extremity injuries during the 2 seasons; acute muscle injuries were the most frequent. Of the 20 strength measures examined, greater quadriceps concentric peak torque at 300 deg/s (HR, 1.005 [95% CI, 1.00-1.01]; P = .037) was the only strength measure identified as significantly associated with a risk of lower extremity injuries in multivariate analysis. Greater quadriceps concentric peak torque at 60 deg/s (HR, 1.004 [95% CI, 1.00-1.01]; P = .026) was associated with the risk of overuse injuries, and greater bilateral adductor strength adjusted for body weight (HR, 0.75 [95% CI, 0.57-0.97; P = .032) was associated with a lower risk for any knee injury. Receiver operating characteristic curve analyses indicated poor predictive ability of the significant strength variables (area under the curve, 0.45-0.56). There was a weak association with the risk of

Apparent target strength in long-rod penetration

Energy Technology Data Exchange (ETDEWEB)

Godwin, R.P.; Chapyak, E.J. [Los Alamos National Lab., NM (United States). Applied Theoretical and Computational Physics Div.

1996-03-01

The authors investigate the apparent enhancement of target strength in the steady-state Tate model of long-rod penetration. They show that computing the effective area over which the target behaves as a fluid provides an explanation of the effective 1-D target strength measured empirically. Expressing the effective target strength as R{sub t} = a {times} Y{sub t}, they postulate that a = A{sub e}/A{sub p}, where Y{sub t} is the nominal strength; A{sub e} is the effective target fluid cross-sectional area and A{sub p} the projectile cross-sectional area. For the case of a rod and projectile of the same material, they use the Tate model together with the jet model of Birkhoff et al. to show a {approx} 4 is likely. Simultaneously satisfying Newton`s Second Law and the Tate model yields a very general derivation of a = 4. By explicitly including strength terms in both the Tate equation and Newton`s Second Law, an even more general a = f(v,{rho}{sub p},{rho}{sub t},Y{sub p},Y{sub t}) can be derived.

A lower extremity strength-based profile of NCAA Division I women's basketball and gymnastics athletes: implications for knee joint injury risk assessment.

Science.gov (United States)

Thompson, Brennan J; Cazier, Curtis S; Bressel, Eadric; Dolny, Dennis G

2018-08-01

This study aimed to provide a comprehensive strength-based physiological profile of women's NCAA Division I basketball and gymnastic athletes; and to make sport-specific comparisons for various strength characteristics of the knee flexor and extensor muscles. A focus on antagonist muscle balance (hamstrings-to-quadriceps ratios, H:Q) was used to elucidate vulnerabilities in these at-risk female athletes. Fourteen NCAA Division I women's basketball and 13 gymnastics athletes performed strength testing of the knee extensors and flexors. Outcome measures included absolute and relative (body mass normalised) peak torque (PT), rate of torque development at 50, 100, 200 ms (RTD50 etc.) and H:Q ratios of all variables. The basketball athletes had greater absolute strength for all variables except for isokinetic PT at 240°s -1 and isometric RTD50 for the knee extensors. Gymnasts showed ~20% weaker body mass relative concentric PT for the knee flexors at 60 and 120°·s -1 , and decreased conventional H:Q ratios at 60 and 240°·s -1 (~15%). These findings suggest that collegiate level gymnastics athletes may be prone to increased ACL injury risk due to deficient knee flexor strength and H:Q strength imbalance. Coaches may use these findings when implementing injury prevention screening and/or for individualised strength training programming centered around an athletes strength-related deficits.

Effects of a Modified German Volume Training Program on Muscular Hypertrophy and Strength.

Science.gov (United States)

Amirthalingam, Theban; Mavros, Yorgi; Wilson, Guy C; Clarke, Jillian L; Mitchell, Lachlan; Hackett, Daniel A

2017-11-01

Amirthalingam, T, Mavros, Y, Wilson, GC, Clarke, JL, Mitchell, L, and Hackett, DA. Effects of a modified German volume training program on muscular hypertrophy and strength. J Strength Cond Res 31(11): 3109-3119, 2017-German Volume Training (GVT), or the 10 sets method, has been used for decades by weightlifters to increase muscle mass. To date, no study has directly examined the training adaptations after GVT. The purpose of this study was to investigate the effect of a modified GVT intervention on muscular hypertrophy and strength. Nineteen healthy men were randomly assign to 6 weeks of 10 or 5 sets of 10 repetitions for specific compound resistance exercises included in a split routine performed 3 times per week. Total and regional lean body mass, muscle thickness, and muscle strength were measured before and after the training program. Across groups, there were significant increases in lean body mass measures, however, greater increases in trunk (p = 0.043; effect size [ES] = -0.21) and arm (p = 0.083; ES = -0.25) lean body mass favored the 5-SET group. No significant increases were found for leg lean body mass or measures of muscle thickness across groups. Significant increases were found across groups for muscular strength, with greater increases in the 5-SET group for bench press (p = 0.014; ES = -0.43) and lat pull-down (p = 0.003; ES = -0.54). It seems that the modified GVT program is no more effective than performing 5 sets per exercise for increasing muscle hypertrophy and strength. To maximize hypertrophic training effects, it is recommended that 4-6 sets per exercise be performed, as it seems gains will plateau beyond this set range and may even regress due to overtraining.

Influence of Anterior Cruciate Ligament Tear on Thigh Muscle Strength and Hamstring-to-Quadriceps Ratio: A Meta-Analysis

Science.gov (United States)

Ahn, Sung-Eun; Park, Min-Ji; Lee, Dae-Hee

2016-01-01

Theoretical compensation after anterior cruciate ligament (ACL) tear could cause quadriceps weakness and hamstring activation, preventing anterior tibial subluxation and affecting the expected hamstring-to-quadriceps ratio. Although quadriceps weakness often occurs after ACL tears, it remains unclear whether hamstring strength and hamstring-to-quadriceps ratio increase in ACL deficient knees. This meta-analysis compared the isokinetic muscle strength of quadriceps and hamstring muscles, and the hamstring-to-quadriceps ratio, of the injured and injured limbs of patients with ACL tears. This meta-analysis included all studies comparing isokinetic thigh muscle strengths and hamstring-to-quadriceps ratio in the injured and uninjured legs of patients with ACL tear, without or before surgery. Thirteen studies were included in the meta-analysis. Quadriceps and hamstring strengths were 22.3 N∙m (95% CI: 15.2 to 29.3 N∙m; Phamstring-to-quadriceps ratio was 4% greater in ACL deficient than in uninjured limbs (95% CI: 1.7% to 6.3%; Phamstring muscles of patients with ACL tear, with the decrease in quadriceps strength being 3-fold greater. These uneven reductions slightly increase the hamstring-to-quadriceps ratio in ACL deficient knees. PMID:26745808

Effects of pH and ionic strength on the thermodynamics of human serum albumin-photosensitizer binding

International Nuclear Information System (INIS)

Jones, Cecil L.; Dickson, TiReJe; Hayes, Ronald; Thomas, Lana

2012-01-01

Highlights: ► The pH dependence of entropy and enthalpy changes was determined for zinc phthalocyanine tetrasulfonic acid, ZnPcS 4 binding to human serum albumin, HSA. ► The ionic strength dependence of entropy and enthalpy changes was determined for ZnPcS 4 acid binding to HSA. ► The primary driving force governing the interaction between ZnPcS 4 and HSA over the range of pH and ionic strength was solution dynamics. ► The interplay between entropy and enthalpy changes was demonstrated. - Abstract: Fluorescence spectroscopy was used to measure the effects of pH and ionic strength on thermodynamic parameters governing the interaction of human serum albumin with zinc phthalocyanine tetrasulfonic acid. Fluorescence emission of zinc phthalocyanine increases at 686 nm with increasing concentrations of the protein. The non-linear correlation between protein concentration and emission of the photosensitizer was fitted using Chipman's analysis to calculate the binding affinities. The standard enthalpy and entropy changes were estimated from van’t Hoff analysis of data that were acquired from temperature ramping studies. Results show that reaction is primarily driven by solution dynamics and that the change in enthalpy for the system becomes increasingly unfavorable with increasing pH and ionic strength. The effect of ionic strength on the entropy change for binding is shown to be significantly greater than the effects of pH. The interplay between entropy and enthalpy changes is demonstrated.

The Effects of Extravehicular Activity (EVA) Glove Pressure on Hand Strength

Science.gov (United States)

Mesloh, Miranda; England, Scott; Benson, Elizabeth; Thompson, Shelby; Rajulu, Sudhakar

2010-01-01

The purpose of this study was to characterize hand strength, while wearing a Phase VI Extravehicular Activity (EVA) glove in an Extravehicular Mobility Unit (EMU) suit. Three types of data were collected: hand grip, lateral pinch, and pulp-2 pinch, wider three different conditions: bare-handed, gloved with no Thermal Micrometeoroid Garment (TMG), and glove with TMG. In addition, during the gloved conditions, subjects were tested when unpressurized and pressurized (43 psi). As a percentage of bare-hand strength, the TMG condition showed reduction in grip strength to 55% unpressurized and 46% pressurized. Without the TMG, grip strength increased to 66% unpressurized and 58% pressurized of bare-hand strength. For lateral pinch strength, the reduction in strength was the same for both pressure conditions and with and without the TMG, about 8.5% of bare-hand Pulp-2 pinch strength with no TMG showed an increase to 122% unpressurized and 115% pressurized of bare-hand strength. While wearing the TMG, pulp-2 pinch strength was 115% of bare-hand strength for both pressure conditions.

Rock strength under explosive loading

International Nuclear Information System (INIS)

Rimer, N.; Proffer, W.

1993-01-01

This presentation emphasizes the importance of a detailed description of the nonlinear deviatoric (strength) response of the surrounding rock in the numerical simulation of underground nuclear explosion phenomenology to the late times needed for test ban monitoring applications. We will show how numerical simulations which match ground motion measurements in volcanic tuffs and in granite use the strength values obtained from laboratory measurements on small core samples of these rocks but also require much lower strength values after the ground motion has interacted with the rock. The underlying physical mechanisms for the implied strength reduction are not yet well understood, and in fact may depend on the particular rock type. However, constitutive models for shock damage and/or effective stress have been used successfully at S-Cubed in both the Geophysics Program (primarily for DARPA) and the Containment Support Program (for DNA) to simulate late time ground motions measured at NTS in many different rock types

Focusing on psychiatric patients′ strengths: A new vision on mental health care in Iran

Directory of Open Access Journals (Sweden)

Ali Zargham-Boroujeni

2015-01-01

Full Text Available Background: Identifying and using the strengths of patients, in practice, is a new territory. Today, the need to educate nurses and psychiatric patients about positive psychology in practice and the importance of understanding and focusing on strengths is clear. However, little is known about the strengths the psychiatric patients use and experience. Thus, this study has been designed and conducted in order to understand how people with psychiatric disorders demonstrate their strengths. Materials and Methods: In the present study, 13 semi-structured, qualitative interviews with patients and 2 focus groups with nurses were carried out. In addition, a qualitative content analysis was used to identify significant strengths. Results: Based on the results, the four main strengths consisted of: Finding a meaning in daily living, work as enduring strength, entertaining activities, and positive relationship. Patients also reported that health care providers rarely focused on patients′ strengths, and experts confirmed these findings. Our findings indicate that patients′ own strengths are a pivotal factor in getting through their illness from their perspective. Conclusions: Despite the enduring legacy of pessimism regarding psychiatric patients, these people have a repertoire of strengths. Nurses should, therefore, have a greater focus on eliciting and nourishing psychiatric patients′ strengths in their care. It is suggested that the theoretical and practical aspects of patients′ strengths be incorporated in nursing school curricula.

Experimental study on compressive strength of sediment brick masonry

Science.gov (United States)

Woen, Ean Lee; Malek, Marlinda Abdul; Mohammed, Bashar S.; Chao-Wei, Tang; Tamunif, Muhammad Thaqif

2018-02-01

The effects of pre-wetted unit bricks, mortar type and slenderness ratio of prisms on the compressive strength and failure mode of newly developed sediment brick have been evaluated and compared to clay brick and cement-sand bricks. The results show that pre-wetted sediment brick masonry exhibits higher compressive strength of up to 20% compared to the dry sediment masonry. Using cement-lime mortar leads to lower compressive strength compared to cement mortar. However, the sediment brick masonry with the cement lime mortar exhibit higher compressive strength in comparison with cement mortar masonry. More of diagonal shear cracks have been observed in the failure mode of the sediment bricks masonry compared to clay and cement-sand bricks masonry that show mostly vertical cracks and crushing. The sediment unit bricks display compressive strength in between clay and cement-sand bricks.

Design and Fabrication of 3D printed Scaffolds with a Mechanical Strength Comparable to Cortical Bone to Repair Large Bone Defects

Science.gov (United States)

Roohani-Esfahani, Seyed-Iman; Newman, Peter; Zreiqat, Hala

2016-01-01

A challenge in regenerating large bone defects under load is to create scaffolds with large and interconnected pores while providing a compressive strength comparable to cortical bone (100-150 MPa). Here we design a novel hexagonal architecture for a glass-ceramic scaffold to fabricate an anisotropic, highly porous three dimensional scaffolds with a compressive strength of 110 MPa. Scaffolds with hexagonal design demonstrated a high fatigue resistance (1,000,000 cycles at 1-10 MPa compressive cyclic load), failure reliability and flexural strength (30 MPa) compared with those for conventional architecture. The obtained strength is 150 times greater than values reported for polymeric and composite scaffolds and 5 times greater than reported values for ceramic and glass scaffolds at similar porosity. These scaffolds open avenues for treatment of load bearing bone defects in orthopaedic, dental and maxillofacial applications.

Spine lateral flexion strength development differences between exercises with pelvic stabilization and without pelvic stabilization

Science.gov (United States)

Straton, Alexandru; Gidu, Diana Victoria; Micu, Alexandru

2015-02-01

Poor lateral flexor muscle strength can be an important source of lumbar/thoracic back pain in women. The purpose of this study was to evaluate pelvic stabilization (PS) and no pelvic stabilization (NoPS) lateral flexion strength exercise training on the development of isolated right and left lateral flexion strength. Isometric torque of the isolated right and left lateral flexion muscles was measured at two positions (0° and 30° opposed angle range of motion) on 42 healthy women before and after 8 weeks of PS and NoPS lateral flexion strength exercise training. Subjects were assigned in three groups, the first (n=14) trained 3 times/week with PS lateral flexion strength exercise, the second (n=14) trained 3 times/week with NoPS lateral flexion strength exercise and the third (control, n=14) did not train. Post training isometric strength values describing PS and NoPS lateral flexion strength improved in greater extent for the PS lateral flexion strength exercise group and in lesser extent for the NoPS lateral flexion strength exercise group, in both angles (pstrength exercises; NoPS lateral flexion strength exercises can be an effective way of training for the spine lateral flexion muscles, if there is no access to PS lateral flexion strength training machines.

Postmenopausal HRT and tibolone in relation to muscle strength and body composition

NARCIS (Netherlands)

Jacobsen, D. E.; Samson, M. M.; Kezic, S.; Verhaar, H. J. J.

2007-01-01

Objectives: Sarcopenia, the loss of muscle mass with age, has a great impact on physical function, and especially in postmenopausal women, who experience a greater decline in muscle strength than do men of similar age. Conventional hormone replacement therapy (HRT) may diminish this loss of muscle

REPETITIVE STRENGTH AMONG STUDENTS OF AGE 14

Directory of Open Access Journals (Sweden)

Besim Halilaj

2014-06-01

Full Text Available The study involved 82 male students of the primary school “Qamil Ilazi” in Kaçanik-Kosovo.Four movement tests, which test the repetitive strength, were conducted: 1. Pull-up, 2. Sit-Up, 3. Back extension, 4. Push-up.The main goal of this study was to verify the actual motor status, respectively the component of the repetitive strength among students of age 14 of masculine gender. In addition to verifying the actual motor status, another objective was to verify the relationship between the variables employed.Basic statistical parameters show a distribution which is not significantly different from the normal distribution, yielded highly correlative values among the repetitive strength tests. Space factorization resulted in extracting two latent squares defined as repetitive strength of arms factor, and repetitive strength of body factor.

The relationships of character strengths with coping, work-related stress, and job satisfaction.

Science.gov (United States)

Harzer, Claudia; Ruch, Willibald

2015-01-01

Personality traits have often been highlighted to relate to how people cope with stressful events. The present paper focuses on character strengths as positive personality traits and examines two basic assumptions that were derived from a core characteristic of character strengths (i.e., to determine how individuals deal with adversities): (1) character strengths correlate with coping and (2) buffer the effects of work-related stress on job satisfaction. Two different samples (i.e., a mixed sample representing various occupations [N = 214] and a nurses sample [N = 175]) filled in measures for character strengths, coping, work-related stress, and job satisfaction. As expected, intellectual, emotional, and interpersonal strengths were related to coping. Interpersonal strengths played a greater role for coping among nurses, as interactions with others are an essential part of their workday. Furthermore, intellectual strengths partially mediated the negative effect of work-related stress on job satisfaction. These findings open a new field for research on the role of personality in coping with work-related stress. Character strengths are trainable personal characteristics, and therefore valuable resources to improve coping with work-related stress and to decrease the negative effects of stress. Further research is needed to investigate this assumed causality.

The relationships of character strengths with coping, work-related stress, and job satisfaction

Directory of Open Access Journals (Sweden)

Claudia eHarzer

2015-02-01

Full Text Available Personality traits have often been highlighted to relate to how people cope with stressful events. The present paper focuses on character strengths as positive personality traits and examines two basic assumptions that were derived from a core characteristic of character strengths (i.e., to determine how individuals deal with adversities: (1 Character strengths correlate with coping and (2 buffer the effects of work-related stress on job satisfaction. Two different samples (i.e., a mixed sample representing various occupations [N = 214] and a nurses sample [N = 175] filled in measures for character strengths, coping, work-related stress, and job satisfaction. As expected, intellectual, emotional, and interpersonal strengths were related to coping. Interpersonal strengths played a greater role for coping among nurses, as interactions with others are an essential part of their workday. Furthermore, intellectual strengths partially mediated the negative effect of work-related stress on job satisfaction. These findings open a new field for research on the role of personality in coping with work-related stress. Character strengths are trainable personal characteristics, and therefore valuable resources to improve coping with work-related stress and to decrease the negative effects of stress. Further research is needed to investigate this assumed causality.

Relationship between muscle strength and fall episodes among the elderly: the Yilan study, Taiwan.

Science.gov (United States)

Yang, Nan-Ping; Hsu, Nai-Wei; Lin, Ching-Heng; Chen, Hsi-Chung; Tsao, Hsuan-Ming; Lo, Su-Shun; Chou, Pesus

2018-04-13

Fall episodes are not unusual among community residents, especially the elderly, and lower muscle strength is an important issue to address in order to prevent falls. A community health survey was conducted in a suburban area of Taiwan, and 1067 older adults were selected for enrollment in the present study. All the enrolled subjects had been visited at their homes; the subjects' strength of both hands and muscle mass of both legs were measured and well-established questionnaires were finished by certificated paramedic staffs. The incidence of fall episodes in the previous 1 year in the Yilan elderly population was 15.1%, and the female predominance was significant. A significantly higher prevalence of cataracts was found in group who experienced a fall in the past year (64% vs. 54.9% in the non-fall group). Mild or more severe dementia was much more prevalent in the group who experienced a recent fall (33.8% vs. 25.7% in the non-fall group). The strength of both hands tested as the physical function was 17.6 ± 8.0 kg in the recent fall group, significantly weaker than that in the non-fall group (20.7 ± 8.7 kg). Multivariate regression analysis revealed a greater weekly exercise duration and greater strength of both hands reduced the occurrence of falls among the whole and the female population. The standardized effect sizes of hand grip strength between both groups, not trivial, were 0.29 and 0.37 for the total population and the female subpopulation respectively. Less weekly exercise duration and weaker muscle strength were f ound to be independent risk factors of fall episode(s) in an elderly Taiwanese population, especially in the female sub-population. Muscle strength, measured by average of both hands grip strength, was the most significantly factor of one-year fall episode(s) accessed retrospectively.

Strength and Drying Shrinkage of Alkali-Activated Slag Paste and Mortar

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Mao-chieh Chi

2012-01-01

Full Text Available The aim of this study is to investigate the strengths and drying shrinkage of alkali-activated slag paste and mortar. Compressive strength, tensile strength, and drying shrinkage of alkali-activated slag paste and mortar were measured with various liquid/slag ratios, sand/slag ratios, curing ages, and curing temperatures. Experimental results show that the higher compressive strength and tensile strength have been observed in the higher curing temperature. At the age of 56 days, AAS mortars show higher compressive strength than Portland cement mortars and AAS mortars with liquid/slag ratio of 0.54 have the highest tensile strength in all AAS mortars. In addition, AAS pastes of the drying shrinkage are higher than AAS mortars. Meanwhile, higher drying shrinkage was observed in AAS mortars than that observed comparable Portland cement mortars.

Does plyometric training improve strength performance? A meta-analysis.

Science.gov (United States)

Sáez-Sáez de Villarreal, Eduardo; Requena, Bernardo; Newton, Robert U

2010-09-01

Majority of the research suggests plyometric training (PT) improves maximal strength performance as measured by 1RM, isometric MVC or slow velocity isokinetic testing. However, the effectiveness of PT depends upon various factors. A meta-analysis of 15 studies with a total of 31 effect sizes (ES) was carried out to analyse the role of various factors on the effects of PT on strength performance. The inclusion criteria for the analysis were: (a) studies using PT programs for lower limb muscles; (b) studies employing true experimental design and valid and reliable measurements; (c) studies including sufficient data to calculate ES. When subjects can adequately follow plyometric exercises, the training gains are independent of fitness level. Subjects in either good or poor physical condition, benefit equally from plyometric work, also men obtain similar strength results to women following PT. In relation to the variables of program design, training volume of less than 10 weeks and with more than 15 sessions, as well as the implementation of high-intensity programs, with more than 40 jumps per session, were the strategies that seem to maximize the probability to obtain significantly greater improvements in performance (p<0.05). In order to optimise strength enhancement, the combination of different types of plyometrics with weight-training would be recommended, rather than utilizing only one form (p<0.05). The responses identified in this analysis are essential and should be considered by the strength and conditioning professional with regard to the most appropriate dose-response trends for PT to optimise strength gains.

Compressive strength, flexural strength and thermal conductivity of autoclaved concrete block made using bottom ash as cement replacement materials

International Nuclear Information System (INIS)

Wongkeo, Watcharapong; Thongsanitgarn, Pailyn; Pimraksa, Kedsarin; Chaipanich, Arnon

2012-01-01

Highlights: ► Autoclaved aerated concrete were produced using coal bottom ash as a cement replacement material. ► Coal bottom ash was found to enhance concrete strengths. ► Thermal conductivity of concrete was not significantly affected. ► X-ray diffraction and thermal analysis show tobermorite formation. -- Abstract: The bottom ash (BA) from Mae Moh power plant, Lampang, Thailand was used as Portland cement replacement to produce lightweight concrete (LWC) by autoclave aerated concrete method. Portland cement type 1, river sand, bottom ash, aluminium powder and calcium hydroxide (Ca(OH) 2 ) were used in this study. BA was used to replace Portland cement at 0%, 10%, 20% and 30% by weight and aluminium powder was added at 0.2% by weight in order to produce the aerated concrete. Compressive strength, flexural and thermal conductivity tests were then carried out after the concrete were autoclaved for 6 h and left in air for 7 days. The results show that the compressive strength, flexural strength and thermal conductivity increased with increased BA content due to tobermorite formation. However, approximately, 20% increase in both compressive (up to 11.61 MPa) and flexural strengths (up to 3.16 MPa) was found for mixes with 30% BA content in comparison to just around 6% increase in the thermal conductivity. Thermogravimetry analysis shows C–S–H formation and X-ray diffraction confirm tobermorite formation in bottom ash lightweight concrete. The use of BA as a cement replacement, therefore, can be seen to have the benefit in enhancing strength of the aerated concrete while achieving comparatively low thermal conductivity when compared to the results of the control Portland cement concrete.

SUSTAINED ISOMETRIC SHOULDER CONTRACTION ON MUSCULAR STRENGTH AND ENDURANCE: A RANDOMIZED CLINICAL TRIAL.

Science.gov (United States)

Myers, Natalie L; Toonstra, Jenny L; Smith, Jacob S; Padgett, Cooper A; Uhl, Tim L

2015-12-01

The Advanced Throwers Ten Exercise Program incorporates sustained isometric contractions in conjunction with dynamic shoulder movements. It has been suggested that incorporating isometric holds may facilitate greater increases in muscular strength and endurance. However, no objective evidence currently exists to support this claim. The purpose of this research was to compare the effects of a sustained muscle contraction resistive training program (Advanced Throwers Ten Program) to a more traditional exercise training protocol to determine if increases in shoulder muscular strength and endurance occur in an otherwise healthy population. It was hypothesized that utilizing a sustained isometric hold during a shoulder scaption exercise from the Advanced Throwers Ten would produce greater increases in shoulder strength and endurance as compared to a traditional training program incorporating a isotonic scapular plane abduction (scaption) exercise. Randomized Clinical Trial. Fifty healthy participants were enrolled in this study, of which 25 were randomized into the traditional training group (age: 26 ± 8, height:172 ± 10 cm, weight: 73 ± 13 kg, Marx Activity Scale: 11 ± 4) and 25 were randomized to the Advanced Throwers Ten group (age: 28 ± 9, height: 169 ± 23 cm, weight: 74 ± 16 kg, Marx Activity Scale: 11 ± 5). No pre-intervention differences existed between the groups (P>0.05). Arm endurance and strength data were collected pre and post intervention using a portable load cell (BTE Evaluator, Hanover, MD). Both within and between group analyses were done in order to investigate average torque (strength) and angular impulse (endurance) changes. The traditional and Advanced Throwers Ten groups both significantly improved torque and angular impulse on both the dominant and non-dominant arms by 10-14%. There were no differences in strength or endurance following the interventions between the two training groups (p>0

Socio-economic considerations of cleaning Greater Vancouver's air

International Nuclear Information System (INIS)

2005-08-01

Socio-economic considerations of better air quality on the Greater Vancouver population and economy were discussed. The purpose of the study was to provide socio-economic information to staff and stakeholders of the Greater Vancouver Regional District (GVRD) who are participating in an Air Quality Management Plan (AQMP) development process and the Sustainable Region Initiative (SRI) process. The study incorporated the following methodologies: identification and review of Canadian, American, and European quantitative socio-economic, cost-benefit, cost effectiveness, competitiveness and health analyses of changes in air quality and measures to improve air quality; interviews with industry representatives in Greater Vancouver on competitiveness impacts of air quality changes and ways to improve air quality; and a qualitative analysis and discussion of secondary quantitative information that identifies and evaluates socio-economic impacts arising from changes in Greater Vancouver air quality. The study concluded that for the Greater Vancouver area, the qualitative analysis of an improvement in Greater Vancouver air quality shows positive socio-economic outcomes, as high positive economic efficiency impacts are expected along with good social quality of life impacts. 149 refs., 30 tabs., 6 appendices

Non-Uniform Compressive Strength of Debonded Sandwich Panels

DEFF Research Database (Denmark)

Nøkkentved, Alexandros; Lundsgaard-Larsen, Christian; Berggreen, Carl Christian

2005-01-01

debonds show a considerable strength reduction with increasing debond diameter, with failure mechanisms varying between fast debond propagation and wrinkling-introduced face compression failure for large and small debonds, respectively. Residual strength predictions are based on intact panel testing...

Impact strength on fiber-reinforced hybrid composite

International Nuclear Information System (INIS)

Firdaus, S M; Nurdina; Ariff, M Azmil

2013-01-01

Acrylonitrile-Butadiene-Styrene (ABS) has been well known composite in automotive players to have light weight with high impact strength material compared to sheet metal material which has high impact strength but heavy in weight. In this project, the impact strength properties of fabricated pure ABS were compared to the eight samples of hybrid ABS composite with different weight percentages of short fibers and particle sizes of ground rubber. The objective was to improve the impact strength in addition of short fibers and ground rubber particles. These samples were then characterized using an un-notched Izod impact test. Results show that the increasing of filler percentage yielded an adverse effect on the impact strength of the hybrid composite. The effect of the ground rubber particulate sizes however are deemed to be marginal than the effect of varying filler percentage based on the collected impact strength data from all physically tested hybrid composites

Strength gradient enhances fatigue resistance of steels

Science.gov (United States)

Ma, Zhiwei; Liu, Jiabin; Wang, Gang; Wang, Hongtao; Wei, Yujie; Gao, Huajian

2016-02-01

Steels are heavily used in infrastructure and the transportation industry, and enhancing their fatigue resistance is a major challenge in materials engineering. In this study, by introducing a gradient microstructure into 304 austenitic steel, which is one of the most widely used types of stainless steel, we show that a strength gradient substantially enhances the fatigue life of the material. Pre-notched samples with negative strength gradients in front of the notch’s tip endure many more fatigue cycles than do samples with positive strength gradients during the crack initiation stage, and samples with either type of gradient perform better than do gradient-free samples with the same average yield strength. However, as a crack grows, samples with positive strength gradients exhibit better resistance to fatigue crack propagation than do samples with negative gradients or no gradient. This study demonstrates a simple and promising strategy for using gradient structures to enhance the fatigue resistance of materials and complements related studies of strength and ductility.

Effect of isometric quadriceps exercise on muscle strength, pain, and function in patients with knee osteoarthritis: a randomized controlled study.

Science.gov (United States)

Anwer, Shahnawaz; Alghadir, Ahmad

2014-05-01

[Purpose] The aim of present study was to investigate the effects of isometric quadriceps exercise on muscle strength, pain, and function in knee osteoarthritis. [Subjects and Methods] Outpatients (N=42, 21 per group; age range 40-65 years; 13 men and 29 women) with osteoarthritis of the knee participated in the study. The experimental group performed isometric exercises including isometric quadriceps, straight leg raising, and isometric hip adduction exercise 5 days a week for 5 weeks, whereas the control group did not performed any exercise program. The outcome measures or dependent variables selected for this study were pain intensity, isometric quadriceps strength, and knee function. These variables were measured using the Numerical Rating Scale (NRS), strength gauge device, and reduced WOMAC index, respectively. All the measurements were taken at baseline (week 0) and at the end of the trial at week 5. [Results] In between-group comparisons, the maximum isometric quadriceps strength, reduction in pain intensity, and improvement in function in the isometric exercise group at the end of the 5th week were significantly greater than those of the control group (pisometric quadriceps exercise program showed beneficial effects on quadriceps muscle strength, pain, and functional disability in patients with osteoarthritis of the knee.

Differential strengths of selection on S-RNases from Physalis and Solanum (Solanaceae

Directory of Open Access Journals (Sweden)

Kohn Joshua R

2011-08-01

Full Text Available Abstract Background The S-RNases of the Solanaceae are highly polymorphic self-incompatibility (S- alleles subject to strong balancing selection. Relatively recent diversification of S-alleles has occurred in the genus Physalis following a historical restriction of S-allele diversity. In contrast, the genus Solanum did not undergo a restriction of S-locus diversity and its S-alleles are generally much older. Because recovery from reduced S-locus diversity should involve increased selection, we employ a statistical framework to ask whether S-locus selection intensities are higher in Physalis than Solanum. Because different S-RNase lineages diversify in Physalis and Solanum, we also ask whether different sites are under selection in different lineages. Results Maximum-likelihood and Bayesian coalescent methods found higher intensities of selection and more sites under significant positive selection in the 48 Physalis S-RNase alleles than the 49 from Solanum. Highest posterior densities of dN/dS (ω estimates show that the strength of selection is greater for Physalis at 36 codons. A nested maximum likelihood method was more conservative, but still found 16 sites with greater selection in Physalis. Neither method found any codons under significantly greater selection in Solanum. A random effects likelihood method that examines data from both taxa jointly confirmed higher selection intensities in Physalis, but did not find different proportions of sites under selection in the two datasets. The greatest differences in strengths of selection were found in the most variable regions of the S-RNases, as expected if these regions encode self-recognition specificities. Clade-specific likelihood models indicated some codons were under greater selection in background Solanum lineages than in specific lineages of Physalis implying that selection on sites may differ among lineages. Conclusions Likelihood and Bayesian methods provide a statistical approach to

Beyond Strain: Personal Strengths and Mental Health of Mexican and Argentinean Dementia Caregivers.

Science.gov (United States)

Sutter, Megan; Perrin, Paul B; Peralta, Silvina Victoria; Stolfi, Miriam E; Morelli, Eliana; Peña Obeso, Leticia Aracely; Arango-Lasprilla, Juan Carlos

2016-07-01

Life expectancy is increasing in Latin America resulting in the need for more family caregivers for older adults with dementia. The purpose of the current study was to examine the relationships between personal strengths (optimism, sense of coherence [SOC], and resilience) and the mental health of dementia caregivers from Latin America. Primary family dementia caregivers (n = 127) were identified via convenience sampling at the Instituto de Neurociencias de San Lucas, Argentina, and CETYS University, in Baja California, Mexico and completed measures of these constructs. Personal strengths explained between 32% and 50% of the variance in caregiver mental health. In a series of hierarchical multiple regressions, more manageability (β = -.38, p = .001), general resilience (β = -.24, p = .012), and social competence (β = -.21, p = .034) were uniquely associated with lower depression. Greater comprehensibility (β = -.28, p = .008) was uniquely associated with decreased burden, and manageability was marginally related (β = -.21, p< .10). Greater optimism (β = .37, p< .001) and manageability (β = .27, p = .004) were uniquely associated with increased life satisfaction. The personal strengths of caregivers in Latin America may be particularly important for their mental health because of the culturally imbedded sense of duty toward older family members. Incorporating strengths-based approaches into research on caregiver interventions in regions where caregiving is a highly culturally valued role such as Latin America may have the potential to improve the mental health of dementia caregivers. © The Author(s) 2015.

Normative Quadriceps and Hamstring Muscle Strength Values for Female, Healthy, Elite Handball and Football Players.

Science.gov (United States)

Risberg, May A; Steffen, Kathrin; Nilstad, Agnethe; Myklebust, Grethe; Kristianslund, Eirik; Moltubakk, Marie M; Krosshaug, Tron

2018-05-23

Risberg, MA, Steffen, K, Nilstad, A, Myklebust, G, Kristianslund, E, Moltubakk, MM, and Krosshaug, T. Normative quadriceps and hamstring muscle strength values for female, healthy, elite handball and football players. J Strength Cond Res XX(X): 000-000, 2018-This study presents normative values for isokinetic knee extension and flexion muscle strength tests in 350 elite, female, handball (n = 150) and football (n = 200) players. Isokinetic concentric muscle strength tests at 60°·sec were recorded bilaterally using a dynamometer. Peak torque (in Newton meter [N·m]), body mass normalized peak torque (N·m·kg), and hamstring to quadriceps ratio (H:Q ratio) for dominant and nondominant legs were recorded. The female elite players were 20.9 ± 4.0 years, started playing at the elite level at the age of 18.2 ± 2.7 years, with a mean of 9.7 ± 2.2 hours of weekly in-season training. Handball players demonstrated greater quadriceps muscle strength compared with football players (11.0%) (p handball players only (p = 0.012).The H:Q ratio was significantly lower for handball players (0.58) compared with football players (0.60) (p handball and football players can be used to set rehabilitation goals for muscle strength after injury and enable comparison with uninjured legs. Significantly greater quadriceps muscle strength was found for handball players compared with football players, also when normalized to body mass.This is an open-access article distributed under the terms of the Creative Commons Attribution-Non Commercial-No Derivatives License 4.0 (CCBY-NC-ND), where it is permissible to download and share the work provided it is properly cited. The work cannot be changed in any way or used commercially without permission from the journal.

Short-Term Effects of Whole-Body Vibration Combined with Task-Related Training on Upper Extremity Function, Spasticity, and Grip Strength in Subjects with Poststroke Hemiplegia: A Pilot Randomized Controlled Trial.

Science.gov (United States)

Lee, Jung-Sun; Kim, Chang-Yong; Kim, Hyeong-Dong

2016-08-01

The aim of this study was to determine the effect of whole-body vibration training combined with task-related training on arm function, spasticity, and grip strength in subjects with poststroke hemiplegia. Forty-five subjects with poststroke were randomly allocated to 3 groups, each with 15 subjects as follows: control group, whole-body vibration group, and whole-body vibration plus task-related training group. Outcome was evaluated by clinical evaluation and measurements of the grip strength before and 4 weeks after intervention. Our results show that there was a significantly greater increase in the Fugl-Meyer scale, maximal grip strength of the affected hand, and grip strength normalized to the less affected hand in subjects undergoing the whole-body vibration training compared with the control group after the test. Furthermore, there was a significantly greater increase in the Wolf motor function test and a decrease in the modified Ashworth spasticity total scores in subjects who underwent whole-body vibration plus task-related training compared with those in the other 2 groups after the test. The findings indicate that the use of whole-body vibration training combined with task-related training has more benefits on the improvement of arm function, spasticity, and maximal grip strength than conventional upper limb training alone or with whole-body vibration in people with poststroke hemiplegia.

Advanced characterization techniques in understanding the roles of nickel in enhancing strength and toughness of submerged arc welding high strength low alloy steel multiple pass welds in the as-welded condition

Science.gov (United States)

Sham, Kin-Ling

Striving for higher strength along with higher toughness is a constant goal in material properties. Even though nickel is known as an effective alloying element in improving the resistance of a steel to impact fracture, it is not fully understood how nickel enhances toughness. It was the goal of this work to assist and further the understanding of how nickel enhanced toughness and maintained strength in particular for high strength low alloy (HSLA) steel submerged arc welding multiple pass welds in the as-welded condition. Using advanced analytical techniques such as electron backscatter diffraction, x-ray diffraction, electron microprobe, differential scanning calorimetry, and thermodynamic modeling software, the effect of nickel was studied with nickel varying from one to five wt. pct. in increments of one wt. pct. in a specific HSLA steel submerged arc welding multiple pass weldment. The test matrix of five different nickel compositions in the as-welded and stress-relieved condition was to meet the targeted mechanical properties with a yield strength greater than or equal to 85 ksi, a ultimate tensile strength greater than or equal to 105 ksi, and a nil ductility temperature less than or equal to -140 degrees F. Mechanical testing demonstrated that nickel content of three wt. pct and greater in the as-welded condition fulfilled the targeted mechanical properties. Therefore, one, three, and five wt. pct. nickel in the as-welded condition was further studied to determine the effect of nickel on primary solidification mode, nickel solute segregation, dendrite thickness, phase transformation temperatures, effective ferrite grain size, dislocation density and strain, grain misorientation distribution, and precipitates. From one to five wt. pct nickel content in the as-welded condition, the primary solidification was shown to change from primary delta-ferrite to primary austenite. The nickel partitioning coefficient increased and dendrite/cellular thickness was

The tensile strength test of thermoplastic materials based on poly(butylene terephtalate

Directory of Open Access Journals (Sweden)

Rzepecka Anna

2017-01-01

Full Text Available Thermoplastic composites go toward making an increasingly greater percentage of all manufacturing polymer composites. They have a lot of beneficial properties and their manufacturing using injecting and extrusion methods is a very easy and cheap process. Their properties significantly overtake the properties of traditional materials and it is the reason for their use. Scientists are continuously carrying out research to find new applications of composites materials in new industries, not only in the automotive or aircraft industry. When thermoplastic composites are manufactured a very important factor is the appropriate accommodation of tensile strength to their predestination. Scientists need to know the behaviour of these materials during the impact of different forces, and the factors of working in normal conditions too. The main aim of this article was macroscopic and microscopic analysis of the structure of thermoplastic composites after static tensile strength test. Materials which were analysed were thermoplastic materials which have poly(butylene terephthalate – PBT matrix reinforced with different content glass fibres – from 10% for 30%. In addition, research showed the necessary force to receive fracture and set their distinguishing characteristic down.

Characteristics of structural loess strength and preliminary framework for joint strength formula

OpenAIRE

Rong-jian Li; Jun-ding Liu; Rui Yan; Wen Zheng; Sheng-jun Shao

2014-01-01

The strength of structural loess consists of the shear strength and tensile strength. In this study, the stress path, the failure envelope of principal stress (Kf line), and the strength failure envelope of structurally intact loess and remolded loess were analyzed through three kinds of tests: the tensile strength test, the uniaxial compressive strength test, and the conventional triaxial shear strength test. Then, in order to describe the tensile strength and shear strength of structural lo...

Performance of repetitive tasks induces decreased grip strength and increased fibrogenic proteins in skeletal muscle: role of force and inflammation.

Directory of Open Access Journals (Sweden)

Samir M Abdelmagid

Full Text Available This study elucidates exposure-response relationships between performance of repetitive tasks, grip strength declines, and fibrogenic-related protein changes in muscles, and their link to inflammation. Specifically, we examined forearm flexor digitorum muscles for changes in connective tissue growth factor (CTGF; a matrix protein associated with fibrosis, collagen type I (Col1; a matrix component, and transforming growth factor beta 1 (TGFB1; an upstream modulator of CTGF and collagen, in rats performing one of two repetitive tasks, with or without anti-inflammatory drugs.To examine the roles of force versus repetition, rats performed either a high repetition negligible force food retrieval task (HRNF, or a high repetition high force handle-pulling task (HRHF, for up to 9 weeks, with results compared to trained only (TR-NF or TR-HF and normal control rats. Grip strength declined with both tasks, with the greatest declines in 9-week HRHF rats. Quantitative PCR (qPCR analyses of HRNF muscles showed increased expression of Col1 in weeks 3-9, and CTGF in weeks 6 and 9. Immunohistochemistry confirmed PCR results, and also showed greater increases of CTGF and collagen matrix in 9-week HRHF rats than 9-week HRNF rats. ELISA, and immunohistochemistry revealed greater increases of TGFB1 in TR-HF and 6-week HRHF, compared to 6-week HRNF rats. To examine the role of inflammation, results from 6-week HRHF rats were compared to rats receiving ibuprofen or anti-TNF-α treatment in HRHF weeks 4-6. Both treatments attenuated HRHF-induced increases in CTGF and fibrosis by 6 weeks of task performance. Ibuprofen attenuated TGFB1 increases and grip strength declines, matching our prior results with anti-TNFα.Performance of highly repetitive tasks was associated with force-dependent declines in grip strength and increased fibrogenic-related proteins in flexor digitorum muscles. These changes were attenuated, at least short-term, by anti-inflammatory treatments.

The comparison of quadriceps muscle strength between sprint runner and normal un-trained individuals (Determined by Kin-Com

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Talebian Moghaddam S "

2002-08-01

Full Text Available Introduction: It is suggested that quadriceps muscle has an important role in stability & mobility of Knee joint in athletics and normal individuals; therefore, the purpose of this study was evaluation of the strength in Power Athletics (PA and Normal Un-trained Individuals (NUI groups. Methods and Materials: 31 Females (20 NUI & 11 PA participated in this study. For measuring the strength, each individual performed 5 continuous concentric-eccentric maximal contraction at angular velocities of 90°/s, 135°/s. Twenty five percent of each individual (Maximum Voluntary Isometric Contraction MVIC was determined and used as Pre-load force. Results: Averages concentric & eccentric torques were greater in PA group in comparison with NUI group. The significant difference (P<0.02 existed between PA and NUI groups. Average concentric torques of quadriceps muscle decreased (with increasing of speed from 90°/s to 135°/s and average eccentric torques increased. Average eccentric torques were greater (P<0.01 in PA & NUI groups in comparison with average concentric torques. Conclusion: PA group strength was greater in comparison with NUI group. This is possibly due to the type of muscle fibers in this group have (greater type II fibers. Accordingly, it is critical to consider the role of eccentric exercise in PA group for preventing sport injury.

Strength and Power Correlates of Throwing Velocity on Subelite Male Cricket Players.

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Freeston, Jonathan L; Carter, Thomas; Whitaker, Gary; Nicholls, Owen; Rooney, Kieron B

2016-06-01

Throwing velocity is an important aspect of fielding in cricket to affect run-outs and reduce the opponent's run-scoring opportunities. Although a relationship between strength and/or power and throwing velocity has been well established in baseball, water polo, and European handball, it has not been adequately explored in cricket. Consequently, this study aimed to determine the relationship between measures of strength and/or power and throwing velocity in cricket players. Seventeen male cricket players (mean ± SD; age, 21.1 ± 1.6 years; height, 1.79 ± 0.06 m; weight, 79.8 ± 6.4 kg) from an elite athlete program were tested for maximal throwing velocity from the stretch position and after a 3-meter shuffle. They were also assessed for strength and power using a range of different measures. Throwing velocity from the stretch position (30.5 ± 2.4 m·s) was significantly related to dominant leg lateral-to-medial jump (LMJ) distance (r = 0.71; p velocity and medicine ball chest pass (MB CP) distance (r = 0.67; p bench press strength (p = 0.90), height (p = 0.33), or weight (p = 0.29). Multiple regression analysis revealed that dominant MB Rot and MB CP explained 66% of the variance. The results were similar for velocity after a shuffle step (31.8 ± 2.1 m·s); however, VJ height reached statistical significance (r = 0.51; p ≤ 0.05). The multiple regression was also similar with MB Rot and MB CP explaining 70% of the variance. The cricketers in this study threw with greater velocity than elite junior and subelite senior cricketers but with lower velocities than elite senior cricketers and collegiate level and professional baseball players. This is the first study to demonstrate a link between strength and/or power and throwing velocity in cricket players and highlight the importance of power development as it relates to throwing velocity. Exercises that more closely simulated the speed (body weight jumps and medicine ball throws) or movement pattern (shoulder IR

Role of graft oversizing in the fixation strength of barbed endovascular grafts.

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Kratzberg, Jarin A; Golzarian, Jafar; Raghavan, Madhavan L

2009-06-01

The role of endovascular graft oversizing on risk of distal graft migration following endovascular aneurysm repair for abdominal aortic aneurysm is poorly understood. A controlled in vitro investigation of the role of oversizing in graft-aorta attachment strength for endovascular grafts (EVGs) with barbs was performed. Barbed stent grafts (N = 20) with controlled graft oversizing varying from 4-45% were fabricated while maintaining other design variables unchanged. A flow loop with physiological flow characteristics and a biosynthetic aortic aneurysm phantom (synthetic aneurysm model with a bovine aortic neck) were developed. The stent grafts were deployed into the aortic neck of the bio-synthetic aortic aneurysm phantom under realistic flow conditions. Computed tomography imaging of the graft-aorta complex was used to document attachment characteristics such as graft apposition, number of barbs penetrated, and penetration depth and angle. The strength of graft attachment to the aortic neck was assessed using mechanical pullout testing. Stent grafts were categorized into four groups based on oversizing: 4-10%; 11-20%; 21-30%; and greater than 30% oversizing. Pullout force, a measure of post-deployment fixation strength was not different between 4-10% (6.23 +/- 1.90 N), 11-20% (6.25 +/- 1.84 N) and 20-30% (5.85 +/- 1.89 N) groups, but significantly lower for the group with greater than 30% oversizing (3.67 +/- 1.41 N). Increasing oversizing caused a proportional decrease in the number of barbs penetrating the aortic wall (correlation = -0.83). Of the 14 barbs available in the stent graft, 89% of the barbs (12.5 of 14 on average) penetrated the aortic wall in the 4-10% oversizing group while only 38% (5.25 of 14) did for the greater than 30% group (P barb penetration were found to be positively correlated to pullout force. Greater than 30% graft oversizing affects both barb penetration and graft apposition adversely resulting in a low pullout force in this in vitro

Influence of refraction index strength on the light propagation in dielectrics material with periodic refraction index

International Nuclear Information System (INIS)

Hidayat, Arif; Latifah, Eny; Kurniati, Diana; Wisodo, Hari

2016-01-01

This study investigated the influence of refraction index strength on the light propagation in refraction index-varied dielectric material. This dielectric material served as photonic lattice. The behavior of light propagation influenced by variation of refraction index in photonic lattice was investigated. Modes of the guiding light were determined numerically using squared-operator iteration method. It was found that the greater the strength of refraction index, the smaller the guiding modes.

The strength compass

DEFF Research Database (Denmark)

Ledertoug, Mette Marie

of agreement/disagreement. Also the child/teacher is asked whether the actual strength is important and if he or she has the possibilities to apply the strength in the school. In a PhDproject ‘Strengths-based Learning - Children’s Character Strengths as Means to their Learning Potential’ 750 Danish children......Individual paper presentation: The ‘Strength Compass’. The results of a PhDresearch project among schoolchildren (age 6-16) identifying VIAstrengths concerning age, gender, mother-tongue-langue and possible child psychiatric diagnosis. Strengths-based interventions in schools have a theoretical...... Psychological Publishing Company. ‘The Strength Compass’ is a computer/Ipad based qualitative tool to identify the strengths of a child by a self-survey or a teacher’s survey. It is designed as a visual analogue scale with a statement of the strength in which the child/teacher may declare the degree...

The effect of increasing strength and approach velocity on triple jump performance.

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Allen, Sam J; Yeadon, M R Fred; King, Mark A

2016-12-08

The triple jump is an athletic event comprising three phases in which the optimal phase ratio (the proportion of each phase to the total distance jumped) is unknown. This study used a planar whole body torque-driven computer simulation model of the ground contact parts of all three phases of the triple jump to investigate the effect of strength and approach velocity on optimal performance. The strength and approach velocity of the simulation model were each increased by up to 30% in 10% increments from baseline data collected from a national standard triple jumper. Increasing strength always resulted in an increased overall jump distance. Increasing approach velocity also typically resulted in an increased overall jump distance but there was a point past which increasing approach velocity without increasing strength did not lead to an increase in overall jump distance. Increasing both strength and approach velocity by 10%, 20%, and 30% led to roughly equivalent increases in overall jump distances. Distances ranged from 14.05m with baseline strength and approach velocity, up to 18.49m with 30% increases in both. Optimal phase ratios were either hop-dominated or balanced, and typically became more balanced when the strength of the model was increased by a greater percentage than its approach velocity. The range of triple jump distances that resulted from the optimisation process suggests that strength and approach velocity are of great importance for triple jump performance. Copyright © 2016 Elsevier Ltd. All rights reserved.

Constitutive modelling of the undrained shear strength of fine grained soils containing gas

Energy Technology Data Exchange (ETDEWEB)

Grozic, J.L.H. [Calgary Univ., AB (Canada); Nadim, F.; Kvalstad, T.J. [Norwegian Geotechnical Inst., Oslo (Norway)

2002-07-01

The behaviour of fine grained gassy soils was studied in order to develop a technique to quantitatively evaluate geohazards. Gas can occur in seabeds either in solution in pore water, undissolved in the form of gas filled voids, or as gas hydrates. In offshore soils, the degree of saturation is generally greater than 90 per cent, resulting in a soil structure with a continuous water phase and a discontinuous gas phase. The presence of methane gas will impact the strength of the soil, which alters its resistance to submarine sliding. This paper presents a constitutive model for determining the undrained shear strength of fine-grained gassy soils to assess the stability of deep water marine slopes for offshore developments. Methane gas is shown to have a beneficial effect on the soil strength in compressive loading, but the peak strength is achieved at larger deformations. The increased strength is a result of compression and solution gas which cause partial drainage and reduced pore pressures. The undrained shear strength of gassy soils was shown to increase with increasing initial consolidation stress, increasing volumetric coefficient of solubility, and increasing initial void ratio. 9 refs., 3 tabs., 6 figs.

Cervical-scapular muscles strength and severity of temporomandibular disorder in women with mechanical neck pain

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Fernanda Pasinato

Full Text Available Abstract Introduction: Changes in cervical muscle function have been observed in patients with neck pain (NP and TMD. However, the relationship between TMD severity and neck muscle strength in the presence/absence of NP is unknown. Objective: To determine the prevalence of TMD in women with and without mechanical NP and assess the cervical-scapular muscle strength and its association with TMD severity. Methods: Fifteen volunteers without neck pain (CG and 14 women with mechanical neck pain (NPG took part and were selected by the Neck Disability Index. The diagnosis and severity of TMD were determined by the Research Diagnostic Criteria for TMD and Temporomandibular Index (TI, respectively. The strength of the upper trapezius muscle, and cervical flexor and extensor muscles was measured by digital hand dynamometer. Results: 64.5% of women with NP and 33.3% without NP were diagnosed with TMD (p = 0.095. The NPG showed lower strength of the cervical flexor (p = 0.044 and extensor (p=0.006 muscles, and higher TI (p = 0.038 than in the CG. It was also verified moderate negative correlation between TI and the strength of dominant (p = 0.046, r = -0.547 and non-dominant (p = 0.007, r = -0.695 upper trapezius, and cervical flexors (p = 0.023, r = -0.606 in the NPG. Conclusion: There was no difference in the prevalence of TMD in women with and without NP. However, women with NP have lower cervical muscle strength - compared to those without NP - which was associated with greater severity of TMD. Thus, in women with NP associated with TMD, it is advisable to assess and address the severity of this dysfunction and identify the cervical-scapular muscles compromise.

Chemically vapor-deposited tungsten: its high temperature strength and ductility

International Nuclear Information System (INIS)

Bryant, W.A.

1977-01-01

The high temperature tensile ductility (as measured by total elongation normal to the growth direction) of chemically vapor-deposited tungsten was found to be significantly greater than previously reported. A correlation was found between ductility and void content. However, voids were found to have essentially no effect on the high temperature strength of this material, which is considerably weaker than powder metallurgy tungsten. (Auth.)

The Gluteus Medius Vs. Thigh Muscles Strength Ratio and Their Relation to Electromyography Amplitude During a Farmer’s Walk Exercise

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Stastny Petr

2015-03-01

Full Text Available The strength ratio between hamstrings and quadriceps (H/Q is associated with knee injuries as well as hip abductor muscle (HAB weakness. Sixteen resistance trained men (age, 32.5 ± 4.2 years performed 5 s maximal isometric contractions at 75° of knee flexion/extension and 15° of hip abduction on a dynamometer. After this isometric test they performed a Farmer´s walk exercise to find out if the muscle strength ratio predicted the electromyography amplitude expressed as a percentage of maximum voluntary isometric contraction (%MVIC. The carried load represented a moderate intensity of 75% of the exercise six repetitions maximum (6RM. Electromyography data from the vastus medialis (VM, vastus lateralis (VL, biceps femoris (BF and gluteus medius (Gmed on each leg were collected during the procedure. The groups selected were participants with H/Q ≥ 0.5, HQ < 0.5, HAB/H ≥ 1, HAB/H < 1, HAB/Q ≥ 0.5 and HAB/Q < 0.5. One way ANOVA showed that Gmed activity was significantly greater in the group with HAB/H < 1 (42 ± 14 %MVIC as compared to HAB/H ≥ 1 (26 ± 10 %MVIC and HAB/Q < 0.5 (47 ± 19 %MVIC compared to HAB/Q ≥ 0.5 (26 ± 12 %MVIC. The individuals with HAB/H < 1 were found to have greater activation of their Gmed during the Farmer’s walk exercise. Individuals with HAB/Q < 0.5 had greater activation of the Gmed. Gmed strength ratios predict the muscle involvement when a moderate amount of the external load is used. The Farmer’s walk is recommended as an exercise which can strengthen the gluteus medius, especially for individuals with a HAB/H ratio < 1 and HAB/Q < 0.5.

Development of LTCC Materials with High Mechanical Strength

International Nuclear Information System (INIS)

Kawai, Shinya; Nishiura, Sousuke; Terashi, Yoshitake; Furuse, Tatsuji

2011-01-01

We have developed LTCC materials suitable for substrates of RF modules used in mobile phone. LTCC can provide excellent solutions to requirements of RF modules, such as down-sizing, embedded elements and high performance. It is also important that LTCC material has high mechanical strength to reduce risk of fracture by mechanical impact. We have established a method of material design for high mechanical strength. There are two successive steps in the concept to achieve high mechanical strength. The first step is to improve mechanical strength by increasing the Young's modulus, and the second step is either further improvement through the Young's modulus or enhancement of the fracture energy. The developed material, so called high-strength LTCC, thus possesses mechanical strength of 400MPa, which is twice as strong as conventional material whose mechanical strength is approximately 200MPa in typical. As a result, high-strength LTCC shows an excellent mechanical reliability, against the drop impact test for example. The paper presents material design and properties of LTCC materials.

Pain severity is associated with muscle strength and peak oxygen uptake in adults with fibromyalgia

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Hooten WM

2014-05-01

Full Text Available W Michael Hooten,1,2 Jolene M Smith,3 Jason S Eldrige,1 David A Olsen,3 W David Mauck,1 Susan M Moeschler11Department of Anesthesiology, 2Department of Psychiatry and Psychology, Mayo Clinic College of Medicine, 3Mayo School of Graduate Medical Education, Rochester, MN, USABackground: The associations between pain, lower extremity strength, and aerobic conditioning have not been widely investigated in adults with fibromyalgia (FM. The principle objective of this study was to investigate the relationship between pain severity and knee strength in patients seeking treatment for FM. A secondary objective was to investigate the relationship between pain scores and aerobic conditioning.Methods: Three measures of knee strength (isokinetic extensor, isokinetic flexor, isometric extensor were quantified in the dominant leg of 69 adults with FM using a dynamometer at speeds of 60 degrees per second (60°/s and 180°/s. Peak oxygen uptake (VO2 was assessed using a cycle ergometer, and pain was assessed using the pain severity subscale of the Multidimensional Pain Inventory.Results: In univariable linear regression analyses using pain severity as the dependent variable, lesser values of isokinetic knee extensor strength at 60°/s (P=0.041 and 180°/s (P=0.010, isokinetic knee flexor strength at 60°/s (P=0.028 and 180°/s (P=0.003, and peak VO2 uptake (P=0.031 were predictive of greater pain severity scores. In multiple variable linear regression models adjusted for age, sex, body mass index, and opioid use, the following associations retained statistical significance; isokinetic knee extensor strength at 60°/s (P=0.020 and 180°/s (P=0.003, isokinetic knee flexor strength at 60°/s (P=0.015 and 180°/s (P=0.001, and peak VO2 uptake (P=0.014. However, no significant associations were found between pain severity and isometric knee extensor strength.Conclusion: The main findings from this study were that lesser values of isokinetic knee strength and peak VO

Insulin resistance and bone strength: findings from the study of midlife in the United States.

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Srikanthan, Preethi; Crandall, Carolyn J; Miller-Martinez, Dana; Seeman, Teresa E; Greendale, Gail A; Binkley, Neil; Karlamangla, Arun S

2014-04-01

Although several studies have noted increased fracture risk in individuals with type 2 diabetes mellitus (T2DM), the pathophysiologic mechanisms underlying this association are not known. We hypothesize that insulin resistance (the key pathology in T2DM) negatively influences bone remodeling and leads to reduced bone strength. Data for this study came from 717 participants in the Biomarker Project of the Midlife in the United States Study (MIDUS II). The homeostasis model assessment of insulin resistance (HOMA-IR) was calculated from fasting morning blood glucose and insulin levels. Projected 2D (areal) bone mineral density (BMD) was measured in the lumbar spine and left hip using dual-energy X-ray absorptiometry (DXA). Femoral neck axis length and width were measured from the hip DXA scans, and combined with BMD and body weight and height to create composite indices of femoral neck strength relative to load in three different failure modes: compression, bending, and impact. We used multiple linear regressions to examine the relationship between HOMA-IR and bone strength, adjusted for age, gender, race/ethnicity, menopausal transition stage (in women), and study site. Greater HOMA-IR was associated with lower values of all three composite indices of femoral neck strength relative to load, but was not associated with BMD in the femoral neck. Every doubling of HOMA-IR was associated with a 0.34 to 0.40 SD decrement in the strength indices (p<0.001). On their own, higher levels of fasting insulin (but not of glucose) were independently associated with lower bone strength. Our study confirms that greater insulin resistance is related to lower femoral neck strength relative to load. Further, we note that hyperinsulinemia, rather than hyperglycemia, underlies this relationship. Although cross-sectional associations do not prove causality, our findings do suggest that insulin resistance and in particular, hyperinsulinemia, may negatively affect bone strength relative to

Comparative evaluation of tensile bond strength of silicone-based denture liners after thermocycling and surface treatment.

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Kaur, Harsimran; Datta, Kusum

2015-01-01

To examine, evaluate, and compare the tensile bond strength of two silicone-based liners; one autopolymerizing and one heat cured, when treated with different chemical etchants to improve their adhesion with denture base resin. Hundred and sixty test specimens of heat-cured polymethyl methacrylate (PMMA) were fabricated; out of which 80 specimens were tested for tensile bond strength after bonding it to autopolymerizing resilient liner (Ufigel P) and rest 80 to heat-cured resilient liner (Molloplast B). Each main group was further divided into four subgroups of 20 specimens each, one to act as a control and three were subjected to surface treatment with different chemical etchants namely dichloromethane, MMA monomer, and chloroform. The two silicone-based denture liners were processed between 2 PMMA specimens (10 mm × 10 mm × 40 mm) in the space provided by a spacer of 3 mm, thermocycled (5-55°C) for 500 cycles, and then their tensile strength measurements were done in the universal testing machine. One-way ANOVA technique showed a highly significant difference in the mean tensile bond strength values for all the groups. The Student's t-test computed values of statistics for the compared groups were greater than the critical values both at 5% and at 1% levels. Surface treatment of denture base resin with chemical etchants prior to the application of silicone-based liner (Ufigel P and Molloplast-B) increased the tensile bond strength. The increase was the highest with specimens subjected to 180 s of MMA surface treatment and the lowest with control group specimens.

Association Between Muscle Wasting and Muscle Strength in Patients WHO Developed Severe Sepsis and Septic Shock.

Science.gov (United States)

Borges, Rodrigo Cerqueira; Soriano, Francisco Garcia

2018-05-11

To evaluate the association between the rectus femoris cross-sectional area (RFCSA) and the muscular strength obtained at the bedside in patients forwarded to the intensive care unit (ICU) for severe sepsis and septic shock. A prospective cohort study. RFCSA was assessed by ultrasound on the following day of the ICU admission and monitored during hospitalization. The patients performed clinical tests of muscle strength (Medical Research Council (MRC) scale and handgrip dynamometry), when they could understand the verbal commands of the examiners. In 37 patients hospitalized for sepsis there was a significant decline in RFCSA of 5.18 (4.49-5.96)cm on the 2nd day of ICU for 4.37 (3.71-5.02)cm at hospital discharge. Differently, the handgrip strength showed an increase from the awakening of 12.00 (7.00-20.00)Kgf to 19.00 (14.00-26.00)Kgf until hospital discharge. Patients in mechanical ventilation had a greater tendency to decline in the RFCSA compared to patients who did not receive mechanical ventilation, however without being significant (p = 0.08). There was a negative association between RFCSA delta (2nd day of ICU - ICU discharge) and handgrip strength (r = 0.51, p < 0.05), and a male and SOFA score positive association with the RFCSA delta. There was an association of RFCSA with clinical muscle strength tests. In addition, it has been shown that sepsis can lead to short-term muscle degradation, regardless of whether they are submitted to mechanical ventilation or not.

Greater happiness for a greater number: Is that possible in Austria?

NARCIS (Netherlands)

R. Veenhoven (Ruut)

2011-01-01

textabstractWhat is the final goal of public policy? Jeremy Bentham (1789) would say: greater happiness for a greater number. He thought of happiness as subjective enjoyment of life; in his words as “the sum of pleasures and pains”. In his time the happiness of the great number could not be measured

Greater happiness for a greater number: Is that possible in Germany?

NARCIS (Netherlands)

R. Veenhoven (Ruut)

2009-01-01

textabstractWhat is the final goal of public policy? Jeremy Bentham (1789) would say: greater happiness for a greater number. He thought of happiness as subjective enjoyment of life; in his words as “the sum of pleasures and pains”. In his time the Happiness of the great number could not be measured

Creep Strength of Nb-1Zr for SP-100 Applications

Science.gov (United States)

Horak, James A.; Egner, Larry K.

1994-07-01

Power systems that are used to provide electrical power in space are designed to optimize conversion of thermal energy to electrical energy and to minimize the mass and volume that must be launched. Only refractory metals and their alloys have sufficient long-term strength for several years of uninterrupted operation at the required temperatures of 1200 K and above. The high power densities and temperatures at which these reactors must operate require the use of liquid-metal coolants. The alloy Nb-1 wt % Zr (Nb-lZr), which exhibits excellent corrosion resistance to alkali liquid-metals at high temperatures, is being considered for the fuel cladding, reactor structural, and heat-transport systems for the SP-100 reactor system. Useful lifetime of this system is limited by creep deformation in the reactor core. Nb-lZr sheet procured to American Society for Testing and Materials (ASTM) specifications for reactor grade and commercial grade has been processed by several different cold work and annealing treatments to attempt to produce the grain structure (size, shape, and distribution of sizes) that provides the maximum creep strength of this alloy at temperatures from 1250 to 1450 K. The effects of grain size, differences in oxygen concentrations, tungsten concentrations, and electron beam and gas tungsten arc weldments on creep strength were studied. Grain size has a large effect on creep strength at 1450 K but only material with a very large grain size (150 μm) exhibits significantly higher creep strength at 1350 K. Differences in oxygen or tungsten concentrations did not affect creep strength, and the creep strengths of weldments were equal to, or greater than, those for base metal.

Physical activity, but not sedentary time, influences bone strength in late adolescence.

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Tan, Vina Ps; Macdonald, Heather M; Gabel, Leigh; McKay, Heather A

2018-03-20

Physical activity is essential for optimal bone strength accrual, but we know little about interactions between physical activity, sedentary time, and bone outcomes in older adolescents. Physical activity (by accelerometer and self-report) positively predicted bone strength and the distal and midshaft tibia in 15-year-old boys and girls. Lean body mass mediated the relationship between physical activity and bone strength in adolescents. To examine the influence of physical activity (PA) and sedentary time on bone strength, structure, and density in older adolescents. We used peripheral quantitative computed tomography to estimate bone strength at the distal tibia (8% site; bone strength index, BSI) and tibial midshaft (50% site; polar strength strain index, SSI p ) in adolescent boys (n = 86; 15.3 ± 0.4 years) and girls (n = 106; 15.3 ± 0.4 years). Using accelerometers (GT1M, Actigraph), we measured moderate-to-vigorous PA (MVPA Accel ), vigorous PA (VPA Accel ), and sedentary time in addition to self-reported MVPA (MVPA PAQ-A ) and impact PA (ImpactPA PAQ-A ). We examined relations between PA and sedentary time and bone outcomes, adjusting for ethnicity, maturity, tibial length, and total body lean mass. At the distal tibia, MVPA Accel and VPA Accel positively predicted BSI (explained 6-7% of the variance, p accounting for lean mass. Sedentary time did not independently predict bone strength at either site. Greater tibial bone strength in active adolescents is mediated, in part, by lean mass. Despite spending most of their day in sedentary pursuits, adolescents' bone strength was not negatively influenced by sedentary time.

Pre-sintered Y-TZP sandblasting: effect on surface roughness, phase transformation, and Y-TZP/veneer bond strength

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Carla Müller Ramos-Tonello

Full Text Available Abstract Sandblasting is a common method to try to improve the Y-TZP/veneer bond strength of dental prostheses, however, it may put stress on zirconia surfaces and could accelerate the t→m phase transformation. Y-TZP sandblasting before sintering could be an alternative to improve surface roughness and bonding strength of veneering ceramic. Objectives. The aim of this study was to analyze the effect of Y-TZP pre-sintering sandblasting on surface roughness, phase transformation, and the Y-TZP/veneer shear bond strength. Material and Methods. The Y-TZP specimen surface underwent sandblasting with aluminum oxide (50 μm pre-sintering (Z-PRE and post-sintering (Z-POS. Z-CTR was not subjected to surface treatment. After ceramic veneer application, the specimens were subjected to shear bond testing. Surface roughness was analyzed by confocal microscopy. Y-TZP monoclinic and tetragonal phases were evaluated by micro-Raman spectroscopy. Shear bond strength and surface roughness data were analyzed by One-way ANOVA and Tukey tests (α=0.05. Differences in the wave numbers and the broadening bands of the Raman spectra were compared among groups. Results. Z-POS (9.73±5.36 MPa and Z-PRE (7.94±2.52 MPa showed the highest bond strength, significantly higher than that of Z-CTR (5.54±2.14 MPa. The Ra of Z-PRE (1.59±0.23 µm was much greater and significantly different from that of Z-CTR (0.29±0.05 µm and Z-POS (0.77±0.13 µm. All groups showed bands typical of the tetragonal (T and monoclinic (M phases. Y-TZP sandblasting before sintering resulted in rougher surfaces but did not increase the shear bond strength compared to post-sintering and increased surface defects. Conclusions. Surface treatment with Al3O2, regardless of the moment and application, improves the results of Y-TZP/veneer bonding and is not a specific cause of t→m transformation.

Musculoskeletal Strength, Balance Performance, and Self-Efficacy in Elderly Ving Tsun Chinese Martial Art Practitioners: Implications for Fall Prevention

Science.gov (United States)

Fong, Shirley S. M.; Ng, Shamay S. M.; Liu, Karen P. Y.; Pang, Marco Y. C.; Lee, H. W.; Chung, Joanne W. Y.; Lam, Priscillia L.; Guo, X.

2014-01-01

Objectives. To (1) compare the bone strength, lower limb muscular strength, functional balance performance, and balance self-efficacy between Ving Tsun (VT) martial art practitioners and nonpractitioners and (2) identify the associations between lower limb muscular strength, functional balance performance, and balance self-efficacy among the VT-trained participants. Methods. Thirty-five VT practitioners (mean age ± SD = 62.7 ± 13.3 years) and 49 nonpractitioners (mean age ± SD = 65.9 ± 10.5 years) participated in the study. The bone strength of the distal radius, lower limb muscular strength, functional balance performance, and balance self-efficacy were assessed using an ultrasound bone sonometer, the five times sit-to-stand test (FTSTS), the Berg balance scale (BBS), and the Chinese version of the activities-specific balance confidence scale, respectively. A multivariate analysis of covariance was performed to compare all the outcome variables between the two groups. Results. Elderly VT practitioners had higher radial bone strength on the dominant side (P < 0.05), greater lower limb muscular strength (P = 0.001), better functional balance performance (P = 0.003), and greater balance confidence (P < 0.001) than the nonpractitioners. Additionally, only the FTSTS time revealed a significant association with the BBS score (r = −0.575,  P = 0.013). Conclusions. VT may be a suitable health-maintenance exercise for the elderly. Our findings may inspire the development of VT fall-prevention exercises for the community-dwelling healthy elderly. PMID:25530782

Musculoskeletal Strength, Balance Performance, and Self-Efficacy in Elderly Ving Tsun Chinese Martial Art Practitioners: Implications for Fall Prevention

Directory of Open Access Journals (Sweden)

Shirley S. M. Fong

2014-01-01

Full Text Available Objectives. To (1 compare the bone strength, lower limb muscular strength, functional balance performance, and balance self-efficacy between Ving Tsun (VT martial art practitioners and nonpractitioners and (2 identify the associations between lower limb muscular strength, functional balance performance, and balance self-efficacy among the VT-trained participants. Methods. Thirty-five VT practitioners (mean age ± SD = 62.7 ± 13.3 years and 49 nonpractitioners (mean age ± SD = 65.9 ± 10.5 years participated in the study. The bone strength of the distal radius, lower limb muscular strength, functional balance performance, and balance self-efficacy were assessed using an ultrasound bone sonometer, the five times sit-to-stand test (FTSTS, the Berg balance scale (BBS, and the Chinese version of the activities-specific balance confidence scale, respectively. A multivariate analysis of covariance was performed to compare all the outcome variables between the two groups. Results. Elderly VT practitioners had higher radial bone strength on the dominant side (P<0.05, greater lower limb muscular strength (P=0.001, better functional balance performance (P=0.003, and greater balance confidence (P<0.001 than the nonpractitioners. Additionally, only the FTSTS time revealed a significant association with the BBS score (r=-0.575, P=0.013. Conclusions. VT may be a suitable health-maintenance exercise for the elderly. Our findings may inspire the development of VT fall-prevention exercises for the community-dwelling healthy elderly.

Musculoskeletal strength, balance performance, and self-efficacy in elderly ving tsun chinese martial art practitioners: implications for fall prevention.

Science.gov (United States)

Fong, Shirley S M; Ng, Shamay S M; Liu, Karen P Y; Pang, Marco Y C; Lee, H W; Chung, Joanne W Y; Lam, Priscillia L; Guo, X

2014-01-01

Objectives. To (1) compare the bone strength, lower limb muscular strength, functional balance performance, and balance self-efficacy between Ving Tsun (VT) martial art practitioners and nonpractitioners and (2) identify the associations between lower limb muscular strength, functional balance performance, and balance self-efficacy among the VT-trained participants. Methods. Thirty-five VT practitioners (mean age ± SD = 62.7 ± 13.3 years) and 49 nonpractitioners (mean age ± SD = 65.9 ± 10.5 years) participated in the study. The bone strength of the distal radius, lower limb muscular strength, functional balance performance, and balance self-efficacy were assessed using an ultrasound bone sonometer, the five times sit-to-stand test (FTSTS), the Berg balance scale (BBS), and the Chinese version of the activities-specific balance confidence scale, respectively. A multivariate analysis of covariance was performed to compare all the outcome variables between the two groups. Results. Elderly VT practitioners had higher radial bone strength on the dominant side (P < 0.05), greater lower limb muscular strength (P = 0.001), better functional balance performance (P = 0.003), and greater balance confidence (P < 0.001) than the nonpractitioners. Additionally, only the FTSTS time revealed a significant association with the BBS score (r = -0.575,  P = 0.013). Conclusions. VT may be a suitable health-maintenance exercise for the elderly. Our findings may inspire the development of VT fall-prevention exercises for the community-dwelling healthy elderly.

Improvements in tongue strength and pressure-generation precision following a tongue-pressure training protocol in older individuals with dysphagia: three case reports.

Science.gov (United States)

Yeates, Erin M; Molfenter, Sonja M; Steele, Catriona M

2008-01-01

Dysphagia, or difficulty swallowing, often occurs secondary to conditions such as stroke, head injury or progressive disease, many of which increase in frequency with advancing age. Sarcopenia, the gradual loss of muscle bulk and strength, can place older individuals at greater risk for dysphagia. Data are reported for three older participants in a pilot trial of a tongue-pressure training therapy. During the experimental therapy protocol, participants performed isometric strength exercises for the tongue as well as tongue pressure accuracy tasks. Biofeedback was provided using the Iowa Oral Performance Instrument (IOPI), an instrument that measures tongue pressure. Treatment outcome measures show increased isometric tongue strength, improved tongue pressure generation accuracy, improved bolus control on videofluoroscopy, and improved functional dietary intake by mouth. These preliminary results indicate that, for these three adults with dysphagia, tongue-pressure training was beneficial for improving both instrumental and functional aspects of swallowing. The experimental treatment protocol holds promise as a rehabilitative tool for various dysphagia populations.

Short rest interval lengths between sets optimally enhance body composition and performance with 8 weeks of strength resistance training in older men.

Science.gov (United States)

Villanueva, Matthew G; Lane, Christianne Joy; Schroeder, E Todd

2015-02-01

To determine if 8 weeks of periodized strength resistance training (RT) utilizing relatively short rest interval lengths (RI) in between sets (SS) would induce greater improvements in body composition and muscular performance, compared to the same RT program utilizing extended RI (SL). 22 male volunteers (SS: n = 11, 65.6 ± 3.4 years; SL: n = 11, 70.3 ± 4.9 years) were assigned to one of two strength RT groups, following 4 weeks of periodized hypertrophic RT (PHRT): strength RT with 60-s RI (SS) or strength RT with 4-min RI (SL). Prior to randomization, all 22 study participants trained 3 days/week, for 4 weeks, targeting hypertrophy; from week 4 to week 12, SS and SL followed the same periodized strength RT program for 8 weeks, with RI the only difference in their RT prescription. Following PHRT, all study participants experienced increases in lean body mass (LBM) (p body strength (p body fat (p high-intensity strength RT with shortened RI induces significantly greater enhancements in body composition, muscular performance, and functional performance, compared to the same RT prescription with extended RI, in older men. Applied professionals may optimize certain RT-induced adaptations, by incorporating shortened RI.

Effect of Hybrid Fibers on the Mechanical Properties of High Strength Concrete

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Hamid H. Hussein, Saeed K. Rejeb Hayder T. Abd

2014-04-01

Full Text Available In this study, high strength concrete of 75 MPa compressive strength was investigated. The experimental program was designed to study the effect of fibers and hybrid fibers (steel and polypropylene fibers on the fresh (workability and wet density and hardened properties (compressive strength, splitting strength, flexural strength and dry density of high strength concrete. Results show that decreases in slump flow of all concrete mixtures containing steel, polypropylene and hybrid fibers compared with control mix (0% fiber. Hybrid high strength concrete with steel and polypropylene fibers showed superior compressive, splitting, flexural strengths over the others concrete without or with single fibers content. The test results indicate that the maximum increase in compressive and flexural strengths are obtains with the hybridization ratio (70%steel + 30% polypropylene and were equal to 14.54% and 23.34% respectively, compared with the control mix. While, the maximum increase in splitting tensile strength with (100% steel fiber + 0 polypropylene is 21.19%. 

Serial Changes of Quadriceps and Hamstring Muscle Strength Following Total Knee Arthroplasty: A Meta-Analysis

Science.gov (United States)

Ahn, Hyeong-Sik; Lee, Dae-Hee

2016-01-01

This meta-analysis was performed to analyze serial changes in thigh muscles, including quadriceps and hamstring muscles, from before to one year after total knee arthroplasty (TKA). All studies sequentially comparing isokinetic quadriceps and hamstring muscle strengths between the TKA side and the contralateral uninjured limb were included in this meta-analysis. Five studies with 7 cohorts were included in this meta-analysis. The mean differences in the strengths of quadriceps and hamstring muscles between the TKA and uninjured sides were greatest three months after surgery (26.8 N∙m, 12.8 N∙m, Phamstring strengths relative to preoperative levels were 9.2 N∙m and 4.9 N∙m, respectively, three months postoperatively (P = 0.041), but were no longer significant after six months and one year. During the year after TKA, quadriceps and hamstring muscle strengths were lowest after 3 months, recovering to preoperative level after six months, but not reaching the muscle strength on the contralateral side. Relative to preoperative levels, the difference in muscle strength between the TKA and contralateral knees was only significant at three months. Because decrease of strength of the quadriceps was significantly greater than decrease in hamstring muscle strength at postoperative three months, early rehabilitation after TKA should focus on recovery of quadriceps muscle strength. PMID:26849808

Effect of 8 weeks of free-weight and machine-based strength training on strength and power performance

Directory of Open Access Journals (Sweden)

Wirth Klaus

2016-12-01

Full Text Available The aim of this study was to evaluate the effectiveness of free-weight and machine-based exercises to increase different strength and speed-strength variables. One hundred twenty male participants (age: 23.8 ± 2.5 years; body height: 181.0 ± 6.8 cm; body mass: 80.2 ± 8.9 kg joined the study. The 2 experimental groups completed an 8 week periodized strength training program that included 2 training sessions per week. The exercises that were used in the strength training programs were the parallel barbell squat and the leg press. Before and after the training period, the 1-repetition-maximum in the barbell squat and the leg press, the squat jump, the countermovement jump and unilateral isometric force (maximal isometric force and the rate of force development were evaluated. To compare each group pre vs. post-intervention, analysis of variance with repeated measures and Scheffé post-hoc tests were used. The leg press group increased their 1-repetition-maximum significantly (p < 0.001, while in the squat group such variables as 1-repetition-maximum, the squat jump and the countermovement jump increased significantly (p < 0.001. The maximal isometric force showed no statistically significant result for the repeated measures factor, while the rate of force development of the squat group even showed a statistically significant decrease. Differences between the 2 experimental groups were detected for the squat jump and the countermovement jump. In comparison with the leg press, the squat might be a better strength training exercise for the development of jump performance.

Strength-ductility relationships in intermediate purity hot-pressed beryllium

International Nuclear Information System (INIS)

Stonehouse, A.J.; Bielawski, C.A.; Paine, R.M.

1977-01-01

The strength of vacuum hot-pressed, intermediate purity beryllium may be substantially increased without sacrifice of the strain capacity of the present grade (S-65) through decrease in the average grain size. Tensile strength of 517 MPa, 0.2% offset yield strength of 414 MPa with minimum 3% tensile elongation in all test directions could be commercially achieved. The tangent modulus of such material is quite attractive and suffers only about 10% degradation from room temperature to 260 0 C. The tangent modulus is dramatically enhanced by the presence of a yield point. The ductility of the materials studied did not appear to be affected by the BeO content across the range of 0.5 to 2.0% using nominal -44 to -15 μm powder particle sizes. All fine-grained pressings exhibited yield points in the as-pressed condition. Either full-density or sub-density hot-pressed billets given a hot isostatic pressing treatment without the use of cans showed only slight yield points after the HIP treatment with essentially the same strength and ductility factors as in the pressed condition. A plot of grain size vs yield strength in the as-pressed condition projects to an intercept with the fracture strength line at about 3 μm grain size. A similar plot after the HIP treatment shows a yield strength line parallel to the fracture strength line with no projected intercept predicting a completely brittle material. (author)

A Strength Training Program for Primary Care Patients, Central Pennsylvania, 2012

Science.gov (United States)

Patel, Vijay A.; Kraschnewski, Jennifer L.; Rovniak, Liza S.; Messina, Dino A.; Stuckey, Heather L.; Curry, William J.; Chuang, Cynthia H.; Sherwood, Lisa L.; Hess, Stacy L.

2014-01-01

Introduction Primary care providers can recommend strength training programs to use “Exercise as Medicine,” yet few studies have examined the interest of primary care patients in these programs. Methods We conducted a cross-sectional survey of primary care patients in central Pennsylvania. Interest in participating in free group-based strength training and weight control programs was assessed, in addition to patient demographics, medical history, and quality of life. Results Among 414 patients, most (61.0%) were aged 54 or older, and 64.0% were female. More patients were interested in a strength training program (55.3%) than in a weight control program (45.4%). Nearly three-quarters (72.8%) of those reporting 10 or more days of poor physical health were interested in a strength training program compared with 49.5% of those reporting no days of poor physical health. After adjusting for potential confounders, those reporting poorer physical health had 2.7 greater odds (95% confidence interval, 1.4–5.1) of being interested in a strength training program compared with those reporting better physical health. Patients with hypertension, diabetes, or high cholesterol were not more interested in a strength training program than those without these conditions. Conclusion Primary care practices may consider offering or referring patients to community-based strength training programs. This study observed high levels of interest in these widely available programs. Practices may also consider screening and referring those with poorer physical health, as they may be the most interested and have the most to gain from participating. PMID:24967829

Greater general startle reflex is associated with greater anxiety levels: a correlational study on 111 young women

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Eleonora ePoli

2015-02-01

Full Text Available Startle eyeblink reflex is a valid non-invasive tool for studying attention, emotion and psychiatric disorders. In the absence of any experimental manipulation, the general (or baseline startle reflex shows a high inter-individual variability, which is often considered task-irrelevant and therefore normalized across participants. Unlike the above view, we hypothesized that greater general startle magnitude is related to participants’ higher anxiety level. 111 healthy young women, after completing the State-Trait Anxiety Inventory, were randomly administered 10 acoustic white noise probes (50 ms, 100 dBA acoustic level while integrated EMG from left and right orbicularis oculi was recorded. Results showed that participants with greater state anxiety levels exhibited larger startle reflex magnitude from the left eye (r109=0.23, p<0.05. Furthermore, individuals who perceived the acoustic probe as more aversive reported the largest anxiety scores (r109=0.28, p<0.05 and had the largest eyeblinks, especially in the left eye (r109 = 0.34, p<0.001. Results suggest that general startle may represent a valid tool for studying the neural excitability underlying anxiety and emotional dysfunction in neurological and mental disorders.

Predicting the Compressive Strength of Concretes Made with ...

African Journals Online (AJOL)

In most of these cases the cause of the collapse could be traced to the strength of the construction materials, mainly concrete. Secondly, experimental ... The compressive strength predictions were compared with predictions from an alternative model based on regression analysis. The results of the study show that for the ...

Permeability, porosity and compressive strength of self-compacting concrete

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Valcuende, M.O.

2005-12-01

Full Text Available Most deterioration affecting the durability of self-compacting concrete structures is mediated by water penetration in the concrete, a condition related to its porous structure. The present study analyzes these two factors. To this end, two types of concrete were prepared, a self-compacting and a traditional vibrated concrete, with different W/C ratios and different types of cement. The results of low-pressure water testing to evaluate permeability and analyses to determine compressive strength and pore size distribution showed that self-compacting concrete has lower capillary porosity than traditional concrete, which would explain its greater resistance to water penetration. Such concrete likewise reached higher strength values, except where large proportions of lime powder with low sand equivalents were used in its manufacture, when lower strength was recorded. Lastly, the depth of water penetration and compressive strength were found to be linearly correlated. That correlation was seen to depend, in turn, on the type of concrete, since for any given strength level, self-compacting concrete was less permeable than the traditional material.

En este trabajo experimental se estudia la penetración de agua en hormigones autocompactables, analizando al mismo tiempo su estructura porosa, pues gran parte de los procesos de deterioro que afectan a la durabilidad de las estructuras están condicionados por estos dos aspectos. Para ello se han fabricado dos tipos de hormigones, uno autocompactable y otro tradicional vibrado, con diferentes relaciones A/C y distintos tipos de cemento. Tras determinar la permeabilidad al agua bajo presión, la resistencia a compresión y las distribuciones de tamaño de poro, los resultados obtenidos ponen de manifiesto que los hormigones autocompactables presentan menor porosidad capilar que los tradicionales, lo que les confiere mejores prestaciones frente a la penetración de agua. Asimismo, dichos hormigones

Brief Report: Loss of Muscle Strength Prior to Knee Replacement: A Question of Anatomic Cross-Sectional Area or Specific Strength?

Science.gov (United States)

Culvenor, Adam G; Hamler, Felix C; Kemnitz, Jana; Wirth, Wolfgang; Eckstein, Felix

2018-02-01

To determine whether loss in thigh muscle strength prior to knee replacement is caused by reductions of muscle strength in the anatomic cross-sectional area or by reductions of specific strength. All 100 of the participants in the Osteoarthritis Initiative who underwent knee replacement and whose medical records included data on thigh isometric muscle strength and magnetic resonance imaging (MRI) (58 women, and 42 men, mean ± SD age 65 ± 8 years, mean ± SD body mass index [BMI] 29 ± 5 kg/m 2 ) were matched with a control (no knee replacement) for age, sex, height, BMI, and radiographic severity. Thigh muscle anatomic cross-sectional area was determined by MRI at the research visit before knee replacement (time 0) and 2 years before time 0 (time -2). Specific strength (strength/anatomic cross-sectional area) was calculated, and the measures were compared by conditional logistic regression (i.e., odds ratio [OR] per standard deviation). ORs adjusted for pain (OR adj ) and 95% confidence intervals (95% CIs) were also calculated. Knee replacement cases had significantly smaller extensor (but not flexor) anatomic cross-sectional areas than controls at time 0 (women, OR adj 1.89 [95% CI 1.05-3.90]; men, OR adj 2.22 [95% CI 1.04-4.76]), whereas no significant differences were found at time -2. Women who had knee replacement showed lower levels of extensor specific strength than controls at time 0 (OR 1.59 [95% CI 1.02-2.50]), although this difference was not observed in men and did not maintain significance after adjustment for pain (OR adj 1.22 [95% CI 0.71-2.08]). Female cases lost significantly more extensor specific strength between time -2 and time 0 than controls (OR adj 3.76 [95% CI 1.04-13.60]), whereas no significant differences were noted at time -2, or in men. Prior to knee replacement, a significant reduction in knee extensor strength appears to occur in women through 2 mechanisms: one driven by pain (loss of specific strength) and one independent of pain

Strength of wood versus rate of testing - A theoretical approach

DEFF Research Database (Denmark)

Nielsen, Lauge Fuglsang

2007-01-01

Strength of wood is normally measured in ramp load experiments. Experience shows that strength increases with increasing rate of testing. This feature is considered theoretically in this paper. It is shown that the influence of testing rate is a phenomenon, which depends on the quality...... of the considered wood. Low quality wood shows lesser influence of testing rate. This observation agrees with the well-known statement made by Borg Madsen that weak wood subjected to a constant load, has a longer lifetime than strong wood. In general, the influence of testing rate on strength increases...

Bond strength of masonry

NARCIS (Netherlands)

Pluijm, van der R.; Vermeltfoort, A.Th.

1992-01-01

Bond strength is not a well defined property of masonry. Normally three types of bond strength can be distinguished: - tensile bond strength, - shear (and torsional) bond strength, - flexural bond strength. In this contribution the behaviour and strength of masonry in deformation controlled uniaxial

Generation and associative encoding in young and old adults: the effect of the strength of association between cues and targets on a cued recall task.

Science.gov (United States)

Taconnat, Laurence; Froger, Charlotte; Sacher, Mathilde; Isingrini, Michel

2008-01-01

The generation effect (i.e., better recall of the generated items than the read items) was investigated with a between-list design in young and elderly participants. The generation task difficulty was manipulated by varying the strength of association between cues and targets. Overall, strong associates were better recalled than weak associates. However, the results showed different generation effect patterns according to strength of association and age, with a greater generation effect for weak associates in younger adults only. These findings suggest that generating weak associates leads to more elaborated encoding, but that elderly adults cannot use this elaborated encoding as well as younger adults to recall the target words at test.

Nutrition guidelines for strength sports: sprinting, weightlifting, throwing events, and bodybuilding.

Science.gov (United States)

Slater, Gary; Phillips, Stuart M

2011-01-01

Strength and power athletes are primarily interested in enhancing power relative to body weight and thus almost all undertake some form of resistance training. While athletes may periodically attempt to promote skeletal muscle hypertrophy, key nutritional issues are broader than those pertinent to hypertrophy and include an appreciation of the sports supplement industry, the strategic timing of nutrient intake to maximize fuelling and recovery objectives, plus achievement of pre-competition body mass requirements. Total energy and macronutrient intakes of strength-power athletes are generally high but intakes tend to be unremarkable when expressed relative to body mass. Greater insight into optimization of dietary intake to achieve nutrition-related goals would be achieved from assessment of nutrient distribution over the day, especially intake before, during, and after exercise. This information is not readily available on strength-power athletes and research is warranted. There is a general void of scientific investigation relating specifically to this unique group of athletes. Until this is resolved, sports nutrition recommendations for strength-power athletes should be directed at the individual athlete, focusing on their specific nutrition-related goals, with an emphasis on the nutritional support of training.

Strength and fracture mechanism of iron reinforced tricalcium phosphate cermet fabricated by spark plasma sintering.

Science.gov (United States)

Tkachenko, Serhii; Horynová, Miroslava; Casas-Luna, Mariano; Diaz-de-la-Torre, Sebastian; Dvořák, Karel; Celko, Ladislav; Kaiser, Jozef; Montufar, Edgar B

2018-05-01

The present work studies the microstructure and mechanical performance of tricalcium phosphate (TCP) based cermet toughened by iron particles. A novelty arises by the employment of spark plasma sintering for fabrication of the cermet. Results showed partial transformation of initial alpha TCP matrix to beta phase and the absence of oxidation of iron particles, as well as a lack of chemical reaction between TCP and iron components during sintering. The values of compressive and tensile strength of TCP/Fe cermet were 3.2 and 2.5 times, respectively, greater than those of monolithic TCP. Fracture analysis revealed the simultaneous action of crack-bridging and crack-deflection microstructural toughening mechanisms under compression. In contrast, under tension the reinforcing mechanism was only crack-bridging, being the reason for smaller increment of strength. Elastic properties of the cermet better matched values reported for human cortical bone. Thereby the new TCP/Fe cermet has potential for eventual use as a material for bone fractures fixation under load-bearing conditions. Copyright © 2018 Elsevier Ltd. All rights reserved.

Predicting Flexural Strength of Concretes Incorporating River Gravel ...

African Journals Online (AJOL)

In most of these cases the cause of the collapse could be traced to the strength of the construction materials which is usually concrete. Secondly, experimental ... The flexural strength predictions were compared with predictions from an alternative model based on regression analysis. The results of the study show that for the ...

Retentive strength of different intracanal posts in restorations of anterior primary teeth: an in vitro study

Directory of Open Access Journals (Sweden)

Mahtab Memarpour

2013-11-01

Full Text Available Objectives To determine the retentive strength and failure mode of undercut composite post, glass fiber post and polyethylene fiber post luted with flowable composite resin and resin-cement. Materials and Methods Coronal parts of 120 primary canine teeth were sectioned and specimens were treated endodontically. The teeth were randomly divided into 6 groups (n = 20. Prepared root canals received intracanal retainers with a short composite post, undercut composite post, glass fiber post luted with flowable resin or resin-cement, and polyethylene fiber post luted with flowable resin or resin-cement. After crown reconstruction, samples were tested for retentive strength and failure mode. Statistical analysis was done with one-way ANOVA and Tukey tests (p < 0.05. Results There were statistically significant differences between groups (p = 0.001. Mean bond strength in the undercut group was significantly greater than in the short composite post (p = 0.030, and the glass fiber post (p = 0.001 and the polyethylene fiber post group luted with resin-cement (p = 0.008. However, the differences between the undercut group and the groups with flowable composite as the luting agent were not significant (p = 0.068, p = 0.557. Adhesive failure was more frequent in the fiber post groups. Conclusions Although the composite post with undercutting showed the greatest resistance to dislodgement, fiber posts cemented with flowable composite resin provided acceptable results in terms of retentive strength and fracture mode.

Single versus double row suture anchor fixation for greater tuberosity fractures - a biomechanical study.

Science.gov (United States)

Seppel, Gernot; Saier, Tim; Martetschläger, Frank; Plath, Johannes E; Guevara-Alvarez, Alberto; Henschel, Julia; Winkler, Martin; Augat, Peter; Imhoff, Andreas B; Buchmann, Stefan

2017-12-01

Fractures of the humeral greater tuberosity (GT) are a frequent injury progressively treated with arthroscopic suture anchor repair. Yet, no biomechanical study has been performed comparing fixation strength of arthroscopic single- (SR) vs. double row (DR) fixation. Standardized fractures of the greater tuberosity were created in 12 fresh frozen proximal humeri. After random assignation to the SR or DR group the fixed humeri were tested applying cyclic loading to the supraspinatus and infraspinatus tendon. Load to failure and fragment displacement were assessed by means of an electrodynamic material testing machine using an optical tracking system. Load to failure values were higher in the DR group (649 N; ±176) than in the SR group (490 N; ±145) however without statistical significance (p = .12). In greater tuberosity displacement of 3-5 mm surgical treatment is recommended. The fixing constructs in this study did not reach displacement landmarks of 3 or 5 mm before construct failure as shown in previous studies. Thus the applied traction force (N) at 1 mm displacement was analyzed. In the SR group the load at 1 mm displacement was 277 N; ±46 compared to 260 N; ±62 in the DR group (p = .65). The results suggest that both techniques are viable options for refixation of greater tuberosity fractures. Laboratory study.

Alkyl chitosan film-high strength, functional biomaterials.

Science.gov (United States)

Lu, Li; Xing, Cao; Xin, Shen; Shitao, Yu; Feng, Su; Shiwei, Liu; Fusheng, Liu; Congxia, Xie

2017-11-01

Biofilm with strong tensile strength is a topic item in the area of tissue engineering, medicine engineering, and so forth. Here we introduced an alkyl chitosan film with strong tensile strength and its possibility for an absorbable anticoagulation material in vivo was tested in the series of blood test, such as dynamic coagulation time, plasma recalcification time and hemolysis. Alkyl chitosan film was a better biomaterial than traditional chitosan film in the anticoagulation, tissue compatibility and cell compatibility. The unique trait of alkyl chitosan film may be for its greater contact angle and hydrophobicity ability to reduce the adsorption capacity for the blood component and the activity of fibrinolytic enzymes, enhance the antibacterial capacity than chitosan film. Moreover, none of chitosan film or butyl chitosan film exhibited quick inflammation or other disadvantage and degraded quickly by implanted test. Therefore, Alkyl chitosan film is of prospective properties as an implantable, absorbable agent for tissue heals, and this material need further research. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 105A: 3034-3041, 2017. © 2017 Wiley Periodicals, Inc.

Weibull statistic analysis of bending strength in the cemented carbide coatings

International Nuclear Information System (INIS)

Yi Yong; Shen Baoluo; Qiu Shaoyu; Li Cong

2003-01-01

The theoretical basis using Weibull statistics to analyze the strength of coating has been established that the Weibull distribution will be the asymptotic distribution of strength for coating as the volume of coating increase, provided that the local strength of coating is statistic independent, and has been confirmed in the following test for the bending strength of two cemented carbide coatings. The result shows that Weibull statistics can be well used to analyze the strength of two coatings. (authors)

Hand grip strength and maximum peak expiratory flow: determinants of bone mineral density of adolescent students.

Science.gov (United States)

Cossio-Bolaños, Marco; Lee-Andruske, Cynthia; de Arruda, Miguel; Luarte-Rocha, Cristian; Almonacid-Fierro, Alejandro; Gómez-Campos, Rossana

2018-03-02

Maintaining and building healthy bones during the lifetime requires a complicated interaction between a number of physiological and lifestyle factors. Our goal of this study was to analyze the association between hand grip strength and the maximum peak expiratory flow with bone mineral density and content in adolescent students. The research team studied 1427 adolescent students of both sexes (750 males and 677 females) between the ages of 11.0 and 18.9 years in the Maule Region of Talca (Chile). Weight, standing height, sitting height, hand grip strength (HGS), and maximum peak expiratory flow (PEF) were measured. Furthermore, bone mineral density (BMD) and total body bone mineral content (BMC) were determined by using the Dual-Energy X-Ray Absorptiometry (DXA). Hand grip strength and PEF were categorized in tertiles (lowest, middle, and highest). Linear regression was performed in steps to analyze the relationship between the variables. Differences between categories were determined through ANOVA. In males, the hand grip strength explained 18-19% of the BMD and 20-23% of the BMC. For the females, the percentage of variation occurred between 12 and 13% of the BMD and 17-18% of the BMC. The variation of PEF for the males was observed as 33% of the BMD and 36% of the BMC. For the females, both the BMD and BMC showed a variation of 19%. The HGS and PEF were divided into three categories (lowest, middle, and highest). In both cases, significant differences occurred in bone density health between the three categories. In conclusion, the HGS and the PEF related positively to the bone density health of both sexes of adolescent students. The adolescents with poor values for hand grip strength and expiratory flow showed reduced values of BMD and BMC for the total body. Furthermore, the PEF had a greater influence on bone density health with respect to the HGS of the adolescents of both sexes.

Uniaxial Compressive Strength and Fracture Mode of Lake Ice at Moderate Strain Rates Based on a Digital Speckle Correlation Method for Deformation Measurement

Directory of Open Access Journals (Sweden)

Jijian Lian

2017-05-01

Full Text Available Better understanding of the complex mechanical properties of ice is the foundation to predict the ice fail process and avoid potential ice threats. In the present study, uniaxial compressive strength and fracture mode of natural lake ice are investigated over moderate strain-rate range of 0.4–10 s−1 at −5 °C and −10 °C. The digital speckle correlation method (DSCM is used for deformation measurement through constructing artificial speckle on ice sample surface in advance, and two dynamic load cells are employed to measure the dynamic load for monitoring the equilibrium of two ends’ forces under high-speed loading. The relationships between uniaxial compressive strength and strain-rate, temperature, loading direction, and air porosity are investigated, and the fracture mode of ice at moderate rates is also discussed. The experimental results show that there exists a significant difference between true strain-rate and nominal strain-rate derived from actuator displacement under dynamic loading conditions. Over the employed strain-rate range, the dynamic uniaxial compressive strength of lake ice shows positive strain-rate sensitivity and decreases with increasing temperature. Ice obtains greater strength values when it is with lower air porosity and loaded vertically. The fracture mode of ice seems to be a combination of splitting failure and crushing failure.

Character strengths, social anxiety, and physiological stress reactivity

Directory of Open Access Journals (Sweden)

Tingting Li

2017-05-01

Full Text Available In this paper, the effects of character strengths on the physiological reactivity to social anxiety induced by the Trier Social Stress Task were reported. On the basis of their scores in the Chinese Virtues Questionnaire, 30 college students were assigned to either high- (n = 15 or low-character-strength (n = 15 groups. Their psychological stress and physiological data across three laboratory stages (namely, baseline, stress exposure, and post-stress were collected. Results indicated that individuals with high character strengths exhibited rapid cardiovascular recovery from baseline to post-stress even if high- and low-character-strength groups showed similar patterns of cardiovascular arousal in response to the stress at baseline and stress exposure. These results prove that character strengths are stress-defense factors that allow for psychological and physiological adaptation to stress.

Trabecular microstructure and surface changes in the greater tuberosity in rotator cuff tears

International Nuclear Information System (INIS)

Jiang, Yebin; Zhao, Jenny; Ouyang, Xiaolong; Genant, Harry K.; Holsbeeck, Marnix T. van; Flynn, Michael J.

2002-01-01

Abstract Objective. When planning surgery in patients with rotator cuff tear, strength of bone at the tendon insertion and trabecular bone structure in the greater tuberosity are usually taken into consideration. We investigated radiographic changes in bone structure of the greater tuberosity in rotator cuff tears.Design. Twenty-two human cadaveric shoulders from subjects ranging from 55 to 75 years of age were obtained. The integrity of the rotator cuff was examined by sonography to determine if it is intact without any tear, or torn partially or completely. The humeral head was sectioned in 3 mm thick coronal slab sections and microradiographed. After digitization of the microradiographs and imaging processing with in-house semi-automated image processing software tools developed using software interfaces on a Sun workstation, the trabecular histomorphometrical structural parameters and connectivity in the greater tuberosity were quantified. The degenerative changes on the surface of the greater tuberosity were interpreted blindly by 2 independent readers.Results. Among the 22 shoulder specimens, the rotator cuff was found intact in 10 shoulders, partially in 7 and fully torn in 5. Statistically significant loss in apparent trabecular bone volume fraction, number of trabecular nodes, and number of trabecular branches, and a statistically significant increase in apparent trabecular separation and number of trabecular free ends were found in the greater tuberosity of the shoulders with tears. The loss was greater in association with full tear than in partial tear. Thickening of the cortical margin of the enthesis, irregularity of its surface, and calcification beyond the tidemark were observed in 2 (20%) shoulders with intact rotator cuff, in 6 (86%) shoulders with partial tear, and in 5 (100%) shoulders with full tear.Conclusions. Rotator cuff tears are associated with degenerative changes on the bone surface and with disuse osteopenia of the greater tuberosity

Balance disorder and increased risk of falls in osteoporosis and kyphosis: significance of kyphotic posture and muscle strength.

Science.gov (United States)

Sinaki, Mehrsheed; Brey, Robert H; Hughes, Christine A; Larson, Dirk R; Kaufman, Kenton R

2005-08-01

This controlled trial was designed to investigate the influence of osteoporosis-related kyphosis (O-K) on falls. Twelve community-dwelling women with O-K (Cobb angle, 50-65 degrees measured from spine radiographs) and 13 healthy women serving as controls were enrolled. Mean age of the O-K group was 76 years (+/-5.1), height 158 cm (+/-5), and weight 61 kg (+/-7.9), and mean age of the control group was 71 years (+/-4.6), height 161 cm (+/-3.8), and weight 66 kg (+/-11.7). Quantitative isometric strength data were collected. Gait was monitored during unobstructed level walking and during stepping over an obstacle of four different heights randomly assigned (2.5%, 5%, 10%, and 15% of the subject's height). Balance was objectively assessed with computerized dynamic posturography consisting of the sensory organization test. Back extensor strength, grip strength, and all lower extremity muscle groups were significantly weaker in the O-K group than the control group (P controls for all conditions of unobstructed and obstructed level walking. Obstacle height had a significant effect on all center-of-mass variables. The O-K subjects had significantly greater balance abnormalities on computerized dynamic posturography than the control group (P =0.002). Data show that thoracic hyperkyphosis on a background of reduced muscle strength plays an important role in increasing body sway, gait unsteadiness, and risk of falls in osteoporosis.

The effect of trait type and strength of selection on heritability and evolvability in an island bird population.

Science.gov (United States)

Wheelwright, Nathaniel T; Keller, Lukas F; Postma, Erik

2014-11-01

The heritability (h(2) ) of fitness traits is often low. Although this has been attributed to directional selection having eroded genetic variation in direct proportion to the strength of selection, heritability does not necessarily reflect a trait's additive genetic variance and evolutionary potential ("evolvability"). Recent studies suggest that the low h(2) of fitness traits in wild populations is caused not by a paucity of additive genetic variance (VA ) but by greater environmental or nonadditive genetic variance (VR ). We examined the relationship between h(2) and variance-standardized selection intensities (i or βσ ), and between evolvability (IA :VA divided by squared phenotypic trait mean) and mean-standardized selection gradients (βμ ). Using 24 years of data from an island population of Savannah sparrows, we show that, across diverse traits, h(2) declines with the strength of selection, whereas IA and IR (VR divided by squared trait mean) are independent of the strength of selection. Within trait types (morphological, reproductive, life-history), h(2) , IA , and IR are all independent of the strength of selection. This indicates that certain traits have low heritability because of increased residual variance due to the age at which they are expressed or the multiple factors influencing their expression, rather than their association with fitness. © 2014 The Author(s). Evolution © 2014 The Society for the Study of Evolution.

Shear strength of shock-loaded polycrystalline tungsten

International Nuclear Information System (INIS)

Asay, J.R.; Chhabildas, L.C.; Dandekar, D.P.

1980-01-01

Previous experiments have suggested that tungsten undergoes a significant loss of shear strength when shock loaded to stresses greater than 7 GPa. In order to investigate this effect in more detail, a series of experiments was conducted in which polycrystalline tungsten was first shock loaded to approximately 10 GPa and then either unloaded or reloaded from the shocked state. Analysis of measured time-resolved wave profiles indicates that during initial compression to 9.7 GPa, the shear stress in polycrystalline tungsten increases to a maximum value of 1.1 GPA near a longitudinal stress of 5 GPa, but decreases to a final value of 0.8 GPa for stresses approaching 10 GPa. During reloading from a longitudinal stress of 9.7 GPa to a final value of approx.14 GPa, the shear stress increases to a peak value of 1.2 GPa and softens to 1.0 GPa in the final state. During unloading from the shocked state, the initial response is elastic with a strong Baushinger effect. Examination of a recovered sample shows evidence for both deformation slipping and twinning, which may be responsible for the observed softening

Determination of mode-I cohesive strength for interfaces

DEFF Research Database (Denmark)

Jørgensen, J. B.; Thouless, M. D.; Sørensen, Bent F.

2016-01-01

The cohesive strength is one of the governing parameters controlling crack deflection at interfaces, but measuring its magnitude is challenging. In this paper, we demonstrate a novel approach to determine the mode-I cohesive strength of an interface by using a 4-point single-edge-notch beam...... in response to this stress, before the main crack starts to grow. Observations using 2D digital-image correlation showed that an ''apparent" strain across the interface initially increases linearly with the applied load, but becomes nonlinear upon the initiation of the interface crack. The cohesive strength...

Decreased Muscle Strength and Quality in Diabetes-Related Dementia

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Akito Tsugawa

2017-12-01

Full Text Available Background/Aims: Diabetes-related dementia (DrD, a dementia subgroup associated with specific diabetes mellitus (DM-related metabolic abnormalities, is clinically and pathophysiologically different from Alzheimer disease (AD and vascular dementia. We determined whether skeletal muscle strength, quality, and mass decrease in individuals with DrD. Methods: We evaluated grip and knee extension strength, muscle mass, and gait speed in 106 patients with probable AD and without type 2 DM (AD[–DM] group, 74 patients with probable AD and with DM (AD[+DM] group, and 36 patients with DrD (DrD group. Muscle quality was defined as the ratio of muscle strength to muscle mass. Results: Both female and male subjects with DrD showed significantly decreased muscle strength and quality in the upper extremities compared with the subjects with AD[–DM] or AD[+DM]. Female subjects with DrD showed significantly decreased muscle quality in the lower extremities compared with the subjects with AD[–DM]. Both female and male subjects with DrD had a significantly lower gait speed compared with the subjects with AD[–DM]. However, there were no significant differences in muscle mass and the prevalence of sarcopenia between the groups. Conclusion: Subjects with DrD showed decreased muscle strength and quality, but not muscle mass, and had a low gait speed.

Comparative evaluation of tensile bond strength of silicone-based denture liners after thermocycling and surface treatment

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Harsimran Kaur

2015-01-01

Full Text Available Purpose: To examine, evaluate, and compare the tensile bond strength of two silicone-based liners; one autopolymerizing and one heat cured, when treated with different chemical etchants to improve their adhesion with denture base resin. Materials and Methods: Hundred and sixty test specimens of heat-cured polymethyl methacrylate (PMMA were fabricated; out of which 80 specimens were tested for tensile bond strength after bonding it to autopolymerizing resilient liner (Ufigel P and rest 80 to heat-cured resilient liner (Molloplast B. Each main group was further divided into four subgroups of 20 specimens each, one to act as a control and three were subjected to surface treatment with different chemical etchants namely dichloromethane, MMA monomer, and chloroform. The two silicone-based denture liners were processed between 2 PMMA specimens (10 mm × 10 mm × 40 mm in the space provided by a spacer of 3 mm, thermocycled (5-55°C for 500 cycles, and then their tensile strength measurements were done in the universal testing machine. Results: One-way ANOVA technique showed a highly significant difference in the mean tensile bond strength values for all the groups. The Student′s t-test computed values of statistics for the compared groups were greater than the critical values both at 5% and at 1% levels. Conclusion: Surface treatment of denture base resin with chemical etchants prior to the application of silicone-based liner (Ufigel P and Molloplast-B increased the tensile bond strength. The increase was the highest with specimens subjected to 180 s of MMA surface treatment and the lowest with control group specimens.

Molecular insights into the biology of Greater Sage-Grouse

Science.gov (United States)

Oyler-McCance, Sara J.; Quinn, Thomas W.

2011-01-01

Recent research on Greater Sage-Grouse (Centrocercus urophasianus) genetics has revealed some important findings. First, multiple paternity in broods is more prevalent than previously thought, and leks do not comprise kin groups. Second, the Greater Sage-Grouse is genetically distinct from the congeneric Gunnison sage-grouse (C. minimus). Third, the Lyon-Mono population in the Mono Basin, spanning the border between Nevada and California, has unique genetic characteristics. Fourth, the previous delineation of western (C. u. phaios) and eastern Greater Sage-Grouse (C. u. urophasianus) is not supported genetically. Fifth, two isolated populations in Washington show indications that genetic diversity has been lost due to population declines and isolation. This chapter examines the use of molecular genetics to understand the biology of Greater Sage-Grouse for the conservation and management of this species and put it into the context of avian ecology based on selected molecular studies.

Effect of organic solvents compared to sandblasting on the repair bond strength of nanohybrid and nanofilled composite resins.

Science.gov (United States)

Brum, Rafael Torres; Vieira, Sergio; Freire, Andrea; Mazur, Rui Fernando; De Souza, Evelise Machado; Rached, Rodrigo Nunes

2017-01-01

This study evaluated the effect of different surface treatments on the repair bond strength of nanohybrid (Empress Direct) and nanofilled (Filtek Z350 XT) composite resins. A total of 120 specimens of each material (7.5 x 4.5 x 3 mm) were prepared and polished with SiC paper. Half of the specimens were kept in water for seven days and the other half for six months; they were then divided into six groups according to the type of surface treatment: negative control (no treatment), Al2O3sandblasted, liquid acetone, acetone gel, liquid alcohol and alcohol gel. Following application of the silane coupling agent and the adhesive system, composite resin cylinders were fabricated on the specimens and light cured (20 seconds). The same composite resins were used for the repair. Additionally, ten intact specimens of each composite resin (without repair) were prepared (positive control). The specimens were then loaded to failure in the microshear mode. Three additional specimens were fabricated in each group, and the surface treatments were analyzed by atomic force microscopy, energy-dispersive X-ray spectroscopy (EDS) and scanning electron microscopy (SEM). The nanofilled composite resin showed higher cohesive strength and repair bond strength than the nanohybrid composite resin. The aging process affected the repair bond strength of the nanofilled composite resin. Al2O3sandblasting was more efficient for the nanofilled composite resin and promoted greater surface roughness in both materials. The solvents demonstrated higher efficacy for the nanohybrid composite resin. The strengths resulting from the solvents were material dependent, and Al2O3sandblasting resulted in superior repair bond strength in both materials.

Strengths-based Learning

DEFF Research Database (Denmark)

Ledertoug, Mette Marie

-being. The Ph.D.-project in Strength-based learning took place in a Danish school with 750 pupils age 6-16 and a similar school was functioning as a control group. The presentation will focus on both the aware-explore-apply processes and the practical implications for the schools involved, and on measurable......Strength-based learning - Children͛s Character Strengths as Means to their Learning Potential͛ is a Ph.D.-project aiming to create a strength-based mindset in school settings and at the same time introducing strength-based interventions as specific tools to improve both learning and well...

Topological strength of magnetic skyrmions

Energy Technology Data Exchange (ETDEWEB)

Bazeia, D.; Ramos, J.G.G.S.; Rodrigues, E.I.B.

2017-02-01

This work deals with magnetic structures that attain integer and half-integer skyrmion numbers. We model and solve the problem analytically, and show how the solutions appear in materials that engender distinct, very specific physical properties, and use them to describe their topological features. In particular, we found a way to model skyrmion with a large transition region correlated with the presence of a two-peak skyrmion number density. Moreover, we run into the issue concerning the topological strength of a vortex-like structure and suggest an experimental realization, important to decide how to modify and measure the topological strength of the magnetic structure.

Effect of ionic strength on the kinetics of ionic and micellar reactions in aqueous solution

International Nuclear Information System (INIS)

Dung, M.H.; Kozak, J.J.

1982-01-01

The effect of electrostatic forces on the rate of reaction between ions in aqueous solutions of intermediate ionic strength is studied in this paper. We consider the kinetics of reactions involving simple ionic species (1--1 and 2--2 electrolyte systems) as well as kinetic processes mediated by the presence of micellar ions (or other charged organizates). In the regime of ionic strength considered, dielectric saturation of the solvent in the vicinity of the reacting ions must be taken into account and this is done by introducing several models to describe the recovery of the solvent from saturation to its continuum dielectric behavior. To explore the effects of ion size, charge number, and ionic strength on the overall rate constant for the process considered, we couple the traditional theory of ionic reactions in aqueous solution with calculations of the electrostatic potential obtained via solution of the nonlinear Poisson--Boltzmann equation. The great flexibility of the nonlinear Poisson--Boltzmann theory allows us to explore quantitatively the influence of each of these effects, and our simulations show that the short-range properties of the electrostatic potential affect primarily kinetically controlled processes (to varying degrees, depending on the ionic system considered) whereas the down-range properties of the potential play a (somewhat) greater role in influencing diffusion-controlled processes. A detailed examination is made of ionic strength effects over a broad range of ionic concentrations. In the regime of low ionic strength, the limiting slope and intercept of the curve describing the dependence of log k/sub D/ on I/sup 1/2//(1+I/sup 1/2/) may differ considerably from the usual Debye--Hueckel limiting relations, depending on the particular model chosen to describe local saturation effects

Maximal power training induced different improvement in throwing velocity and muscle strength according to playing positions in elite male handball players.

Science.gov (United States)

Cherif, M; Chtourou, H; Souissi, N; Aouidet, A; Chamari, K

2016-12-01

This study was designed to assess the effect of strength and power training on throwing velocity and muscle strength in handball players according to their playing positions. Twenty-two male handball players were assigned to either an experimental group (n=11) or a control group (n=11) (age: 22.1 ± 3.0 years). They were asked to complete (i) the ball throwing velocity test and (ii) the one-repetition maximum (1-RM) tests for the half-back squat, the pull-over, the bench press, the developed neck, and the print exercises before and after 12 weeks of maximal power training. The training was designed to improve strength and power with an intensity of 85-95% of the 1RM. In addition to their usual routine handball training sessions, participants performed two sessions per week. During each session, they performed 3-5 sets of 3-8 repetitions with 3 min of rest in between. Then, they performed specific shots (i.e., 12 to 40). Ball-throwing velocity (p<0.001) was higher after the training period in rear line players (RL). The training programme resulted in an improvement of 1RM bench press (p<0.001), 1RM developed neck (p<0.001) and 1RM print (p<0.001) in both front line (FL) and RL. The control group showed a significant improvement only in ball-throwing velocity (p<0.01) and 1RM bench press (p<0.01) in RL. A significantly greater improvement was found in ball-throwing velocity (p<0.001), 1RM bench press (p<0.001), and 1RM half-back squat exercises in players of the central axis (CA) compared to the lateral axis (LA) (p<0.01). The power training programme induced significantly greater increases in ball-throwing velocity and muscle strength in FL than RL and in CA than LA axis players.

The German Version of the Strengths Use Scale: The Relation of Using Individual Strengths and Well-being

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Alexandra Huber

2017-04-01

Full Text Available Theoretical perspectives in positive psychology have considered the possession and use of strengths equally but in applied research more studies focused on having them, probably due to the absence of psychometrically adequate scales. Therefore, the aim of this study was to assess the psychometric characteristics of the German language version of the Strengths Use Scale (SUS and to explore relationships between strengths use and several indicator measures of well-being: the presence of positive and the absence of negative affect, self-esteem as identity aspect, vitality as self-regulatory resource, and stress for capturing the evaluation of difficulties and obstacles impinging on well-being. The original English version of the SUS was translated following recommended independent forward-backward translation techniques. Exploratory and confirmatory factor analyses were conducted, including a German-speaking convenience sample of university students (N = 374. Additionally, the relations of strengths use and well-being indicators were analyzed. Factorial validity revealed a single-factor structure of the German version of the SUS, explaining 58.4% variance (factor loadings: 0.58 to 0.86, approving the scale’s design and showing high internal consistency (Cronbach’s α 0.95. The hypothesized positive relationships of strengths use with positive affect, self-esteem, and vitality were confirmed as well as the negative relationships with negative affect and stress. The German version of the SUS is psychometrically sound and data indicate that individual strengths use and well-being related measures interact. The instrument can be recommended for future research questions such as if and how the promotion of applying individual strengths during education enhances levels of well-being, or how the implementation of strengths use in job-design guidelines or working conditions can result in higher levels of well-being or healthiness.

Electric and Magnetic Dipole Strength at Low Energy

Science.gov (United States)

Sieja, K.

2017-08-01

A low-energy enhancement of radiative strength functions was deduced from recent experiments in several mass regions of nuclei, which is believed to impact considerably the calculated neutron capture rates. In this Letter we investigate the behavior of the low-energy γ -ray strength of the Sc 44 isotope, for the first time taking into account both electric and magnetic dipole contributions obtained coherently in the same theoretical approach. The calculations are performed using the large-scale shell-model framework in a full 1 ℏω s d -p f -g d s model space. Our results corroborate previous theoretical findings for the low-energy enhancement of the M 1 strength but show quite different behavior for the E 1 strength.

Radiographic features of tuberculous osteitis in greater trochanter and lschium

International Nuclear Information System (INIS)

Hahm, So Hee; Lee, Ye Ri; Kim, Dong Jin; Sung, Ki Jun; Lim, Jong Nam

1996-01-01

To evaluate, if possible, the radiographic features of tuberculous osteitis in the greater trochanter and ischium, and to determine the cause of the lesions. We reterospectively reviewed the plain radiographic findings of 14 ptients with histologically proven tuberculous osteitis involving the greater trochanter and ischium. In each case, the following were analyzed:morphology of bone destruction, including cortical erosion;periosteal reaction;presence or abscence of calcific shadows in adjacent soft tissue. On the basis of an analysis of radiographic features and correlation of the anatomy with adjacent structures we attempted to determine causes. Of the 14 cases evaluated, 12 showed varrious degrees of extrinsic erosion on the outer cortical bone of the greater trochanter and ischium ; in two cases, bone destruction was so severe that the radiographic features of advanced perforated osteomyelitis were simulated. In addition to findings of bone destruction, in these twelve cases, the presence of sequestrum or calcific shadows was seen in adjacent soft tissue. Tuberculous osteitis in the greater trochanter and ischium showed the characteristic findings of chronic extrinsic erosion. On the basis of these findings we can suggest that these lesions result from an extrinsic pathophysiologic cause such as adjacent bursitis

Radiographic features of tuberculous osteitis in greater trochanter and lschium

Energy Technology Data Exchange (ETDEWEB)

Hahm, So Hee; Lee, Ye Ri [Hanil Hospital Affiliated to KEPCO, Seoul (Korea, Republic of); Kim, Dong Jin; Sung, Ki Jun [Yonsei Univ. Wonju College of Medicine, Wonju (Korea, Republic of); Lim, Jong Nam [Konkuk Univ. College of Medicine, Seoul (Korea, Republic of)

1996-11-01

To evaluate, if possible, the radiographic features of tuberculous osteitis in the greater trochanter and ischium, and to determine the cause of the lesions. We reterospectively reviewed the plain radiographic findings of 14 ptients with histologically proven tuberculous osteitis involving the greater trochanter and ischium. In each case, the following were analyzed:morphology of bone destruction, including cortical erosion;periosteal reaction;presence or abscence of calcific shadows in adjacent soft tissue. On the basis of an analysis of radiographic features and correlation of the anatomy with adjacent structures we attempted to determine causes. Of the 14 cases evaluated, 12 showed varrious degrees of extrinsic erosion on the outer cortical bone of the greater trochanter and ischium ; in two cases, bone destruction was so severe that the radiographic features of advanced perforated osteomyelitis were simulated. In addition to findings of bone destruction, in these twelve cases, the presence of sequestrum or calcific shadows was seen in adjacent soft tissue. Tuberculous osteitis in the greater trochanter and ischium showed the characteristic findings of chronic extrinsic erosion. On the basis of these findings we can suggest that these lesions result from an extrinsic pathophysiologic cause such as adjacent bursitis.

Are only Emotional Strengths Emotional? Character Strengths and Disposition to Positive Emotions.

Science.gov (United States)

Güsewell, Angelika; Ruch, Willibald

2012-07-01

This study aimed to examine the relations between character strengths and dispositional positive emotions (i.e. joy, contentment, pride, love, compassion, amusement, and awe). A sample of 574 German-speaking adults filled in the Dispositional Positive Emotion Scales (DPES; Shiota, Keltner, & John, 2006), and the Values in Action Inventory of Strengths (VIA-IS; Peterson, Park, & Seligman, 2005). The factorial structure of the DPES was examined on item level. Joy and contentment could not be clearly separated; the items of the other five emotions loaded on separate factors. A confirmatory factor analysis assuming two latent factors (self-oriented and object/situation specific) was computed on scale level. Results confirmed the existence of these factors, but also indicated that the seven emotions did not split up into two clearly separable families. Correlations between dispositional positive emotions and character strengths were positive and generally low to moderate; a few theoretically meaningful strengths-emotions pairs yielded coefficients>.40. Finally, the link between five character strengths factors (i.e. emotional strengths, interpersonal strengths, strengths of restraint, intellectual strengths, and theological strengths) and the emotional dispositions was examined. Each of the factors displayed a distinctive "emotional pattern"; emotional strengths evidenced the most numerous and strongest links to emotional dispositions. © 2012 The Authors. Applied Psychology: Health and Well-Being © 2012 The International Association of Applied Psychology.

COMPARATIVE STUDY OF THE SHEAR BOND STRENGTH OF COMPOSITE RESIN TO DENTAL ENAMEL CONDITIONED WITH PHOSPHORIC ACID OR Nd: YAG LASER

Directory of Open Access Journals (Sweden)

EDUARDO Carlos de Paula

1997-01-01

Full Text Available This study has been focused on a comparison between the shear bond strength of a composite resin attached to dental enamel surface, after a 35% phosphoric acid etching and after a Nd:YAG laser irradiation with 165.8 J/cm2 of energy density per pulse. After etching and attaching resin to these surfaces, the specimens were thermocycled and then underwent the shearing bond strength tests at a speed of 5 mm/min. The results achieved, after statistical analysis with Student's t-test, showed that the adhesion was significantly greater in the 35% phosphoric acid treated group than in the group treated with the Nd:YAG laser, thus demonstrating the need for developing new studies to reach the ideal parameters for an effective enamel surface conditioning as well as specific adhesives and composite resins when Nd:YAG laser is used

Strength Characteristics of Groundnut Leaf/Stem Ash (GLSA) Concrete

Science.gov (United States)

Oseni, O. W.; Audu, M. T.

2016-09-01

The compressive strength properties of concrete are substantial factors in the design and construction of concrete structures. Compressive strength directly affects the degree to which the concrete can be able to carry a load over time. These changes are complemented by deflections, cracks etc., in the structural elements of concrete. This research investigated the effect of groundnut leaf/stem ash (GLSA) on the compressive strength of concrete at 0%, 5 %, 10 % and 15 % replacements of cement. The effect of the water-cement ratio on properties such as the compressive strength, slump, flow and workability properties of groundnut leaf/stem ash (GLSA) mixes with OPC were evaluated to determine whether they are acceptable for use in concrete structural elements. A normal concrete mix with cement at 100 % (i.e., GLSA at 0%) with concrete grade C25 that can attain an average strength of 25 N/mm2 at 28 days was used as a control at design water-cement ratios of 0.65 and grading of (0.5-32) mm from fine to coarse aggregates was tested for: (1) compressive strength, and the (2) slump and flow Test. The results and observations showed that the concrete mixes from GLSA at 5 - 15 % ratios exhibit: pozzolanic properties and GLSA could be used as a partial replacement for cement at these percentage mix ratios compared with the control concrete; an increase in the water-cement ratio showed a significant decrease in the compressive strength and an increase in workability. Therefore, it is important that all concrete mixes exude an acceptably designed water-cement ratio for compressive strength characteristics for use in structures, water-cement ratio is a significant factor.

Controlling adsorption and passivation properties of bovine serum albumin on silica surfaces by ionic strength modulation and cross-linking.

Science.gov (United States)

Park, Jae Hyeon; Sut, Tun Naw; Jackman, Joshua A; Ferhan, Abdul Rahim; Yoon, Bo Kyeong; Cho, Nam-Joon

2017-03-29

Understanding the physicochemical factors that influence protein adsorption onto solid supports holds wide relevance for fundamental insights into protein structure and function as well as for applications such as surface passivation. Ionic strength is a key parameter that influences protein adsorption, although how its modulation might be utilized to prepare well-coated protein adlayers remains to be explored. Herein, we investigated how ionic strength can be utilized to control the adsorption and passivation properties of bovine serum albumin (BSA) on silica surfaces. As protein stability in solution can influence adsorption kinetics, the size distribution and secondary structure of proteins in solution were first characterized by dynamic light scattering (DLS), nanoparticle tracking analysis (NTA), and circular dichroism (CD) spectroscopy. A non-monotonic correlation between ionic strength and protein aggregation was observed and attributed to colloidal agglomeration, while the primarily α-helical character of the protein in solution was maintained in all cases. Quartz crystal microbalance-dissipation (QCM-D) experiments were then conducted in order to track protein adsorption onto silica surfaces as a function of ionic strength, and the measurement responses indicated that total protein uptake at saturation coverage is lower with increasing ionic strength. In turn, the QCM-D data and the corresponding Voigt-Voinova model analysis support that the surface area per bound protein molecule is greater with increasing ionic strength. While higher protein uptake under lower ionic strengths by itself did not result in greater surface passivation under subsequent physiologically relevant conditions, the treatment of adsorbed protein layers with a gluteraldehyde cross-linking agent stabilized the bound protein in this case and significantly improved surface passivation. Collectively, our findings demonstrate that ionic strength modulation influences BSA adsorption

Compression strength perpendicular to grain of structural timber and glulam

DEFF Research Database (Denmark)

Damkilde, Lars; Hoffmeyer, Preben; Pedersen, Torben N.

1998-01-01

The characteristic strength values for compression perpendicular to grain as they appear in EN 338 (structural timber) and EN 1194 (glulam) are currently up for discussion. The present paper provides experimental results based on EN 1193 that may assist in the correct assignment of such strength...... values. The dominant failure mode of glulam specimens is shown to be fundamentally different from that of structural timber specimens. Glulam specimens often show tension perpendicular to grain failure before the compression strength value is reached. Such failure mode is not seen for structural timber....... Nonetheless test results show that the levels of characteristic compression strength perpendicular to grain are of the same order for structural timber and glulam. The values are slightly lower than those appearing in EN 1194 and less than half of those appearing in EN 338. The paper presents a numerical...

Possible stimuli for strength and power adaptation : acute metabolic responses.

Science.gov (United States)

Crewther, Blair; Cronin, John; Keogh, Justin

2006-01-01

The metabolic response to resistance exercise, in particular lactic acid or lactate, has a marked influence upon the muscular environment, which may enhance the training stimulus (e.g. motor unit activation, hormones or muscle damage) and thereby contribute to strength and power adaptation. Hypertrophy schemes have resulted in greater lactate responses (%) than neuronal and dynamic power schemes, suggesting possible metabolic-mediated changes in muscle growth. Factors such as age, sex, training experience and nutrition may also influence the lactate responses to resistance exercise and thereafter, muscular adaptation. Although the importance of the mechanical and hormonal stimulus to strength and power adaptation is well recognised, the contribution of the metabolic stimulus is largely unknown. Relatively few studies for example, have examined metabolic change across neuronal and dynamic power schemes, and not withstanding the fact that those mechanisms underpinning muscular adaptation, in relation to the metabolic stimulus, remain highly speculative. Inconsistent findings and methodological limitations within research (e.g. programme design, sampling period, number of samples) make interpretation further difficult. We contend that strength and power research needs to investigate those metabolic mechanisms likely to contribute to weight-training adaptation. Further research is also needed to examine the metabolic responses to different loading schemes, as well as interactions across age, sex and training status, so our understanding of how to optimise strength and power development is improved.

Methodological aspects of functional neuroimaging at high field strength: a critical review

International Nuclear Information System (INIS)

Scheef, L.; Landsberg, M.W.; Boecker, H.

2007-01-01

The last few years have proven that high field magnetic resonance imaging (MRI) is superior in nearly every way to conventional equipment up to 1.5 tesla (T). Following the global success of 3T-scanners in research institutes and medical practices, a new generation of MRI devices with field strengths of 7T and higher is now on the horizon. The introduction of ultra high fields has brought MRI technology closer to the physical limitations and increasingly greater costs are required to achieve this goal. This article provides a critical overview of the advantages and problems of functional neuroimaging using ultra high field strengths. This review is principally limited to T2*-based functional imaging techniques not dependent on contrast agents. The main issues include the significance of high field technology with respect to SNR, CNR, resolution, and sequences, as well as artifacts, noise exposure, and SAR. Of great relevance is the discussion of parallel imaging, which will presumably determine the further development of high and ultra high field strengths. Finally, the importance of high field strengths for functional neuroimaging is explained by selected publications. (orig.)

Effectiveness of Traditional Strength vs. Power Training on Muscle Strength, Power and Speed with Youth: A Systematic Review and Meta-Analysis

Science.gov (United States)

Behm, David G.; Young, James D.; Whitten, Joseph H. D.; Reid, Jonathan C.; Quigley, Patrick J.; Low, Jonathan; Li, Yimeng; Lima, Camila D.; Hodgson, Daniel D.; Chaouachi, Anis; Prieske, Olaf; Granacher, Urs

2017-01-01

Numerous national associations and multiple reviews have documented the safety and efficacy of strength training for children and adolescents. The literature highlights the significant training-induced increases in strength associated with youth strength training. However, the effectiveness of youth strength training programs to improve power measures is not as clear. This discrepancy may be related to training and testing specificity. Most prior youth strength training programs emphasized lower intensity resistance with relatively slow movements. Since power activities typically involve higher intensity, explosive-like contractions with higher angular velocities (e.g., plyometrics), there is a conflict between the training medium and testing measures. This meta-analysis compared strength (e.g., training with resistance or body mass) and power training programs (e.g., plyometric training) on proxies of muscle strength, power, and speed. A systematic literature search using a Boolean Search Strategy was conducted in the electronic databases PubMed, SPORT Discus, Web of Science, and Google Scholar and revealed 652 hits. After perusal of title, abstract, and full text, 107 studies were eligible for inclusion in this systematic review and meta-analysis. The meta-analysis showed small to moderate magnitude changes for training specificity with jump measures. In other words, power training was more effective than strength training for improving youth jump height. For sprint measures, strength training was more effective than power training with youth. Furthermore, strength training exhibited consistently large magnitude changes to lower body strength measures, which contrasted with the generally trivial, small and moderate magnitude training improvements of power training upon lower body strength, sprint and jump measures, respectively. Maturity related inadequacies in eccentric strength and balance might influence the lack of training specificity with the unilateral

Effectiveness of Traditional Strength vs. Power Training on Muscle Strength, Power and Speed with Youth: A Systematic Review and Meta-Analysis

Directory of Open Access Journals (Sweden)

David G. Behm

2017-06-01

Full Text Available Numerous national associations and multiple reviews have documented the safety and efficacy of strength training for children and adolescents. The literature highlights the significant training-induced increases in strength associated with youth strength training. However, the effectiveness of youth strength training programs to improve power measures is not as clear. This discrepancy may be related to training and testing specificity. Most prior youth strength training programs emphasized lower intensity resistance with relatively slow movements. Since power activities typically involve higher intensity, explosive-like contractions with higher angular velocities (e.g., plyometrics, there is a conflict between the training medium and testing measures. This meta-analysis compared strength (e.g., training with resistance or body mass and power training programs (e.g., plyometric training on proxies of muscle strength, power, and speed. A systematic literature search using a Boolean Search Strategy was conducted in the electronic databases PubMed, SPORT Discus, Web of Science, and Google Scholar and revealed 652 hits. After perusal of title, abstract, and full text, 107 studies were eligible for inclusion in this systematic review and meta-analysis. The meta-analysis showed small to moderate magnitude changes for training specificity with jump measures. In other words, power training was more effective than strength training for improving youth jump height. For sprint measures, strength training was more effective than power training with youth. Furthermore, strength training exhibited consistently large magnitude changes to lower body strength measures, which contrasted with the generally trivial, small and moderate magnitude training improvements of power training upon lower body strength, sprint and jump measures, respectively. Maturity related inadequacies in eccentric strength and balance might influence the lack of training specificity with

Influence of silica fume on the strength of high strength concrete

International Nuclear Information System (INIS)

Akram, T.; Memon, S.A.; Khan, S.A.

2007-01-01

HSC (High Strength Concrete) does not become evident by a sudden change in the behavior of 'ordinary strength' concrete. There is a gradual effect that becomes more noticeable when the strength level exceeds about 40-45 MPa. There cannot be a precise level of strength which defines this change in effect. The effects are on strength and workability, requiring us to take into account in our mix proportioning, the ramifications of fineness of cement on workability and of type of aggregate and aggregate/cement ratio on strength. In fact, the selection of materials becomes more critical as the concrete strength increases and that if very high strength is required (100 MPa and higher), relatively few materials may be suitable. An experimental investigation is carried out to evaluate the feasibility of producing HSC using locally available materials and to study the influence of silica fume on the strength of HSC. The main variables in this research is amount of silica fume. The parameters that are kept constant are the amount of cement equal to 580 kg/m3, dosage of HRWRA (High Range Water Reducing Admictures) equal to 4 % by weight of cementitious materials and the ratio of fine aggregate to coarse aggregate (1:2.3). Test results revealed that it is feasible to produce HSC using locally available materials. The optimum percentage of silica fume was found to be 15 % by weight of cement. (author)

Does muscle strength predict future musculoskeletal disorders and sickness absence?

DEFF Research Database (Denmark)

Faber, A; Sell, L; Hansen, J V

2012-01-01

High muscle strength is considered relevant for preventing musculoskeletal disorders and long-term sickness absence. However, prospective studies on the association between muscle strength and future musculoskeletal disorders and long-term sickness absence are few and show contrasting results....

Three-Sheet Spot Welding of Advanced High-Strength Steels

DEFF Research Database (Denmark)

Nielsen, Chris Valentin; Friis, Kasper Storgaard; Zhang, W.

2011-01-01

The automotive industry has introduced the three-layer weld configuration, which represents new challenges compared to normal two-sheet lap welds. The process is further complicated by introducing high-strength steels in the joint. The present article investigates the weldability of thin, low....... The weld mechanisms are analyzed numerically and compared with metallographic analyses showing how the primary bonding mechanism between the thin, low-carbon steel sheet and the thicker sheet of high-strength steel is solid-state bonding, whereas the two high-strength steels are joined by melting, forming...... a weld nugget at their mutual interface. Despite the absence of the typical fusion nugget through the interface between the low-carbon steel and high-strength steel, the weld strengths obtained are acceptable. The failure mechanism in destructive testing is ductile fracture with plug failure....

Association Between Maximal Bench Press Strength and Isometric Handgrip Strength Among Breast Cancer Survivors.

Science.gov (United States)

Rogers, Benjamin H; Brown, Justin C; Gater, David R; Schmitz, Kathryn H

2017-02-01

To characterize the relationship between 1-repetition maximum (1-RM) bench press strength and isometric handgrip strength among breast cancer survivors. Cross-sectional study. Laboratory. Community-dwelling breast cancer survivors (N=295). Not applicable. 1-RM bench press strength was measured with a barbell and exercise bench. Isometric handgrip strength was measured using an isometric dynamometer, with 3 maximal contractions of the left and right hands. All measures were conducted by staff with training in clinical exercise testing. Among 295 breast cancer survivors, 1-RM bench press strength was 18.2±6.1kg (range, 2.2-43.0kg), and isometric handgrip strength was 23.5±5.8kg (range, 9.0-43.0kg). The strongest correlate of 1-RM bench press strength was the average isometric handgrip strength of both hands (r=.399; Pisometric handgrip strength of both hands overestimated 1-RM bench press strength by 4.7kg (95% limits of agreement, -8.2 to 17.6kg). In a multivariable linear regression model, the average isometric handgrip strength of both hands (β=.31; Pstrength (R 2 =.23). Isometric handgrip strength is a poor surrogate for 1-RM bench press strength among breast cancer survivors. 1-RM bench press strength and isometric handgrip strength quantify distinct components of muscular strength. Copyright © 2016 American Congress of Rehabilitation Medicine. Published by Elsevier Inc. All rights reserved.

Pinch Strengths in Healthy Iranian Children and Young Adult Population

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Iman Dianat

2015-03-01

Full Text Available Background: Data on the physical strength capabilities are essential for design-ing safe and usable products and are useful in a wide range of clinical settings especially during treatment of disease affecting the function of the hand. The purpose of this study was to determine peak lateral pinch strength, key pinch strength, tip-to-tip pinch strength and three-jaw pinch strength exertions in a healthy Iranian children and young adult population.Methods: The study was conducted among 511 participants (242 males and 269 females aged 7-30 years. Measurements were carried out with both dominant and non-dominant hands in standard sitting posture using a B&L pinch gauge. Two repetitions of each strength measurement were recorded for each condition and the average value of the two trials was used in the subsequent analysis.Results: The results showed significant differences in the pinch strength data in terms of the age, gender and hand dominance. The lateral pinch strength, key pinch strength, tip-to-tip pinch strength and three-jaw pinch strength exertions by females were 68.4%, 68.8%, 78.8% and 81.8% of those exerted by males, respectively. Strength exertions with the non-dominant hand were 6.4%, 5.2%, 6.6% and 5.1% lower than strength exertions of the dominant hand for the lat-eral pinch strength, key pinch strength, tip-to-tip pinch strength and three-jaw pinch strength exertions, respectively.Conclusion: These findings can be used to fill the gaps in strength data for Iranian population.

The sensory strength of voluntary visual imagery predicts visual working memory capacity.

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Keogh, Rebecca; Pearson, Joel

2014-10-09

How much we can actively hold in mind is severely limited and differs greatly from one person to the next. Why some individuals have greater capacities than others is largely unknown. Here, we investigated why such large variations in visual working memory (VWM) capacity might occur, by examining the relationship between visual working memory and visual mental imagery. To assess visual working memory capacity participants were required to remember the orientation of a number of Gabor patches and make subsequent judgments about relative changes in orientation. The sensory strength of voluntary imagery was measured using a previously documented binocular rivalry paradigm. Participants with greater imagery strength also had greater visual working memory capacity. However, they were no better on a verbal number working memory task. Introducing a uniform luminous background during the retention interval of the visual working memory task reduced memory capacity, but only for those with strong imagery. Likewise, for the good imagers increasing background luminance during imagery generation reduced its effect on subsequent binocular rivalry. Luminance increases did not affect any of the subgroups on the verbal number working memory task. Together, these results suggest that luminance was disrupting sensory mechanisms common to both visual working memory and imagery, and not a general working memory system. The disruptive selectivity of background luminance suggests that good imagers, unlike moderate or poor imagers, may use imagery as a mnemonic strategy to perform the visual working memory task. © 2014 ARVO.

Influence of Anterior Cruciate Ligament Tear on Thigh Muscle Strength and Hamstring-to-Quadriceps Ratio: A Meta-Analysis.

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Hyun-Jung Kim

Full Text Available Theoretical compensation after anterior cruciate ligament (ACL tear could cause quadriceps weakness and hamstring activation, preventing anterior tibial subluxation and affecting the expected hamstring-to-quadriceps ratio. Although quadriceps weakness often occurs after ACL tears, it remains unclear whether hamstring strength and hamstring-to-quadriceps ratio increase in ACL deficient knees. This meta-analysis compared the isokinetic muscle strength of quadriceps and hamstring muscles, and the hamstring-to-quadriceps ratio, of the injured and injured limbs of patients with ACL tears. This meta-analysis included all studies comparing isokinetic thigh muscle strengths and hamstring-to-quadriceps ratio in the injured and uninjured legs of patients with ACL tear, without or before surgery. Thirteen studies were included in the meta-analysis. Quadriceps and hamstring strengths were 22.3 N∙m (95% CI: 15.2 to 29.3 N∙m; P<0.001 and 7.4 N∙m (95% CI: 4.3 to 10.5 N∙m; P<0.001 lower, respectively, on the injured than on the uninjured side. The mean hamstring-to-quadriceps ratio was 4% greater in ACL deficient than in uninjured limbs (95% CI: 1.7% to 6.3%; P<0.001. Conclusively, Decreases were observed in both the quadriceps and hamstring muscles of patients with ACL tear, with the decrease in quadriceps strength being 3-fold greater. These uneven reductions slightly increase the hamstring-to-quadriceps ratio in ACL deficient knees.

GlobeLand30 shows little cropland area loss but greater fragmentation in China

Science.gov (United States)

Yu, Qiangyi; Hu, Qiong; van Vliet, Jasper; Verburg, Peter H.; Wu, Wenbin

2018-04-01

Understanding of cropland dynamics in a large geographical extent is mostly based on observations of area change, while the changes in landscape pattern are hardly assessed. The total amount of cropland in China has remained relatively stable in recent years, which might suggest there was little change. In this analysis, we combine the number of cropland patches (NP) with the total cropland area (TA) for a more comprehensive characterization of cropland change in China. We use GlobeLand30-a global land cover dataset with a 30 m resolution for the years 2000 and 2010-and characterize changes in TA and NP for each county as increase, stable, or decrease. This characterization shows that 703 out of 2420 counties experienced both cropland loss and increased fragmentation. The predominant cropland loss in these areas, especially in the North China Plain, is converted to artificial land. Another 212 are characterized by the opposite developments: an increase in cropland and decreased fragmentation. These counties, are mainly characterized by a conversion of forest areas and grassland areas. It suggests that the cropland conservation policy in China effectively protected the total cropland area in overall, but the consequences in terms of fragmentation might be underestimated. Counties with no obvious change in both indicators, measuring 279 counties, are mainly located in the Southeast. Our results are further compared with local level case studies: the fair consistency indicates alternatives of applying GlobeLand30 for analyzing landscape changes across scales and for cross-site comparisons.

Reduction of cervical and respiratory muscle strength in patients with chronic nonspecific neck pain and having moderate to severe disability.

Science.gov (United States)

López-de-Uralde-Villanueva, Ibai; Sollano-Vallez, Ernesto; Del Corral, Tamara

2017-06-11

To investigate whether patients with chronic nonspecific neck pain and having moderate to severe disability have a greater cervical motor function impairment and respiratory disturbances compared with patients with chronic nonspecific neck pain having mild disability and asymptomatic subjects; and the association between these outcomes in patients with chronic nonspecific neck pain and healthy controls. Cross-sectional study, 44 patients with chronic nonspecific neck pain and 31 healthy subjects participated. The neck disability index was used to divide the patients into 2 groups: 1) mild disability group (scores between 5 and 14 points); and 2) moderate to severe disability group (scores >14 points). Cervical motor function was measured by cervical range of motion, forward head posture, neck flexor, and extensor muscle strength. Respiratory function and maximum respiratory pressures were also measured. Statistically differences were found between the patients with chronic nonspecific neck pain having a moderate to severe disability and the asymptomatic subjects for cervical and respiratory muscle strength. Comparisons between chronic nonspecific neck pain and the asymptomatic groups showed differences for all the variables, except for forward head posture. The regression model determined that strength of cervical flexion explained 36.4 and 45.6% of the variance of maximum inspiratory pressures and maximum expiratory pressures, respectively. Only the chronic nonspecific neck pain group with moderate to severe disability showed differences compared with the healthy subjects. Neck muscle strength could be a good predictor of respiratory muscle function. Implications for rehabilitation Neck pain severity could be closely associated with decreased respiratory pressure in patients with chronic nonspecific neck pain. These findings suggest a new therapeutic approach for patients with moderate to severe disability, such as respiratory muscle training. The regression

Effects of soil strength on the relation of water-use efficiency and growth to carbon isotope discrimination in wheat seedlings

International Nuclear Information System (INIS)

Masle, J.; Farquhar, G.D.

1988-01-01

The ratio of carbon accumulation to transpiration, W, of wheat (Triticum aestivum L.) seedlings increased with increasing soil strength, measured as soil penetrometer resistance, and this was already apparent at the two leaf stage. The ratio was negatively correlated with carbon isotope discrimination, in accord with theory. This means that decrease in intercellular partial pressure of CO 2 accounted for an important part of the increase in W with increasing soil strength. Despite a lower CO 2 concentration in the leaves at high soil strength, assimilation rate per unit leaf area was enhanced. Greater ribulose 1,5-bisphosphate carboxylase activity confirmed that photosynthetic capacity was actually increased. This pattern of opposite variation of assimilation rate and of stomatal conductance is unusual. The ratio of plant carbon mass to leaf area increased markedly with increasing soil strength, mainly because of a greater investment of carbon into roots than into shoots. A strong negative correlation was found between this ratio and carbon isotope discrimination. For a given increase in discrimination, decrease in carbon mass per leaf area was proportionally larger than decrease in assimilation rate, so that relative growth rate was positively correlated to carbon isotope discrimination

The flexural strength and microhardness of YBa2Cu3O6+δ

International Nuclear Information System (INIS)

Ihm, M.K.; Powell, B.R.; Bloink, R.L.

1989-01-01

The flexural strengths of rectangular YBa 2 Cu 3 O 6+δ bars, prepared from mixed oxides and carbonates, or spray dried precursors have been measured at room temperature and at 77K. Strengths ranged from 17.8 to 57.6 MPa at room temperature, depending on processing history, and were twenty percent greater when measured at 77K. Corrosion of YBa 2 Cu 3 O 6+δ in humid air at 38 0 C created two layers of corrosion products, but did not weaken the uncorroded core when failure loads were corrected for the decreased sample dimensions. The Knoop hardness of polycrystalline YBa 2 Cu 3 O 6+δ ranged from 436 to 447 KHN while the hardness of individual grains of YBa 2 Cu 3 O 6+δ was 498 KHN. Variations in flexural strength with microstructure were observed and are discussed

Effects of combination of whey protein intake and rehabilitation on muscle strength and daily movements in patients with hip fracture in the early postoperative period.

Science.gov (United States)

Niitsu, Masaya; Ichinose, Daisuke; Hirooka, Taku; Mitsutomi, Kazuhiko; Morimoto, Yoshitaka; Sarukawa, Junichiro; Nishikino, Shoichi; Yamauchi, Katsuya; Yamazaki, Kaoru

2016-08-01

Elderly patients can be at risk of protein catabolism and malnutrition in the early postoperative period. Whey protein includes most essential amino acids and stimulates the synthesis of muscle protein. The purpose of this study was to investigate the effect of resistance training in combination with whey protein intake in the early postoperative period. We randomized patients to a whey protein group or a control group. The former group received 32.2 g of whey protein pre- and post-rehabilitation in the early postoperative period for two weeks. Outcomes were knee extension strength on either side by Biodex 4.0, and the ability of transfer, walking, toilet use and stair use by the Barthel Index (BI). We performed initial and final assessments in the second and tenth rehabilitation sessions. A total of 38 patients were recruited: 20 in the whey protein group and 18 in the control group. Participants in the whey protein group showed significantly greater improvement in knee extension strength in the operated limb compared with the control group (F = 6.11, P = 0.02). The non-operated limb also showed a similar tendency (F = 3.51, P = 0.07). The abilities of transfer, walking and toilet use showed greater improvements in the whey protein group than in the control group by BI (P patients with hip fracture. Copyright © 2015 Elsevier Ltd and European Society for Clinical Nutrition and Metabolism. All rights reserved.

Strength Training for Middle- and Long-Distance Performance: A Meta-Analysis.

Science.gov (United States)

Berryman, Nicolas; Mujika, Inigo; Arvisais, Denis; Roubeix, Marie; Binet, Carl; Bosquet, Laurent

2018-01-01

To assess the net effects of strength training on middle- and long-distance performance through a meta-analysis of the available literature. Three databases were searched, from which 28 of 554 potential studies met all inclusion criteria. Standardized mean differences (SMDs) were calculated and weighted by the inverse of variance to calculate an overall effect and its 95% confidence interval (CI). Subgroup analyses were conducted to determine whether the strength-training intensity, duration, and frequency and population performance level, age, sex, and sport were outcomes that might influence the magnitude of the effect. The implementation of a strength-training mesocycle in running, cycling, cross-country skiing, and swimming was associated with moderate improvements in middle- and long-distance performance (net SMD [95%CI] = 0.52 [0.33-0.70]). These results were associated with improvements in the energy cost of locomotion (0.65 [0.32-0.98]), maximal force (0.99 [0.80-1.18]), and maximal power (0.50 [0.34-0.67]). Maximal-force training led to greater improvements than other intensities. Subgroup analyses also revealed that beneficial effects on performance were consistent irrespective of the athletes' level. Taken together, these results provide a framework that supports the implementation of strength training in addition to traditional sport-specific training to improve middle- and long-distance performance, mainly through improvements in the energy cost of locomotion, maximal power, and maximal strength.

AND EXPLOSIVE STRENGTH OF YOUNG GYMNASTS

Directory of Open Access Journals (Sweden)

G. Dallas

2014-08-01

Full Text Available The purpose of this study was to examine the acute effect of a single bout of whole body vibration (WBV on flexibility and explosive strength of lower limbs in young artistic gymnasts. Thirty-two young competitive gymnasts volunteered to participate in this study, and were allocated to either the vibration group or traditional body weight training according to the vibration protocol. The vibration intervention consisted of a single bout of eccentric and concentric squatting movements on a vibration platform that was turned on (vibration group: VG n=15, whereas the traditional body weight (no vibration group performed the same training protocol with the WBV device turned off (NVG: n= 17. Flexibility (sit and reach test and explosive strength tests [squat jump (SJ, counter movement jump (CMJ, and single leg squat (right leg (RL and left leg (LL] were performed initially (pre-test, immediately after the intervention (post-test 1, and 15 minutes after the end of the intervention programme (post-test 15. Four 2x3 ANOVAs were used to examine the interaction between group (VG vs NVG and time (pre, post 1, and post 15 with respect to examined variables. The results revealed that a significant interaction between group and time was found with respect to SJ (p 0.05. Further, the percentage improvement of the VG was significantly greater in all examined variables compared to the NVG. This study concluded that WBV training improves flexibility and explosive strength of lower limbs in young trained artistic gymnasts and maintains the initial level of performance for at least 15 minutes after the WBV intervention programme.

Distinguishing Relational Aspects of Character Strengths with Subjective and Psychological Well-being

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Melanie Hausler

2017-07-01

Full Text Available Research has shown that character strengths are positively linked with well-being in general. However, there has not been a fine-grained analysis up to date. This study examines the individual relational aspects between the 24 character strengths, subjective well-being (SWB, and different aspects of psychological well-being (PWB at two times of measurement (N = 117. Results showed that overall the “good character” was significantly stronger related with PWB than with SWB. The character strength “hope” was at least moderately correlated with the PWB aspects meaning, optimism and autonomy, and “zest” with the PWB aspects relationships and engagement. “Persistence” showed the highest correlation with the PWB aspect mastery. Out of the 24 character strengths, the happiness-related strengths (hope, zest, gratitude, curiosity, and love were more likely to correlate with PWB and SWB than any other character strength. This study offers a more fine-grained and thorough understanding of specific relational aspects between the 24 character strengths and a broad range of well-being aspects. Future studies should take up a detailed strategy when exploring relationships between character strengths and well-being.

Compressive strength improvement for recycled concrete aggregate

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Mohammed Dhiyaa

2018-01-01

Full Text Available Increasing amount of construction waste and, concrete remnants, in particular pose a serious problem. Concrete waste exist in large amounts, do not decay and need long time for disintegration. Therefore, in this work old demolished concrete is crashed and recycled to produce recycled concrete aggregate which can be reused in new concrete production. The effect of using recycled aggregate on concrete compressive strength has been experimentally investigated; silica fume admixture also is used to improve recycled concrete aggregate compressive strength. The main parameters in this study are recycled aggregate and silica fume admixture. The percent of recycled aggregate ranged from (0-100 %. While the silica fume ranged from (0-10 %. The experimental results show that the average concrete compressive strength decreases from 30.85 MPa to 17.58 MPa when the recycled aggregate percentage increased from 0% to 100%. While, when silica fume is used the concrete compressive strength increase again to 29.2 MPa for samples with 100% of recycled aggregate.

Bond strength between zirconium ceramic and dual resinous cement

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João Galan Junior

2010-04-01

Full Text Available Objective: To assess the influence of different surface treatments on the bond strength between the resinous cement Panavia F (Kuraray Co. Ltd., Osaka, Japan and the structure of In-Ceram YZ (Vita Zahnfabrik, Bad Säckingen, Germany. Methods: Fifteen ceramic blocks were assessed: Group 1, finishing with abrasive paper; Group 2, finishing, airborne Al2O3 particle abrasion and silanization; Group 3, finishing, airborne particle abrasion, silicatization and silanization. After treatment, the blocks received cementation of resin composite cylinders with Panavia F (Kuraray Co. Ltd., Osaka, Japan and were submitted to the shear bond strength test in a universal testing machine. Results: The results were statistically analyzed (ANOVA and multiple comparison Student-Newman-Keuls test: Group 1 (9.66 ± 1.67 MPa < Group 2 (16.61 ± 3.38 MPa = Group 3 (19.23 ± 5.69 MPa, with p = 0.007. Conclusion: The structures of the In-Ceram YZ system (Vita Zahnfabrik, Bad Säckingen, Germany associated with Panavia F (Kuraray Co. Ltd., Osaka, Japan require previous etching to achieve greater bond strength between the ceramic and cement, and this treatment may be performed with airborne particle abrasion I or traditional silicatization, both followed by silanization.

Strength development of high-strength ductile concrete incorporating Metakaolin and PVA fibers.

Science.gov (United States)

Nuruddin, Muhammad Fadhil; Khan, Sadaqat Ullah; Shafiq, Nasir; Ayub, Tehmina

2014-01-01

The mechanical properties of high-strength ductile concrete (HSDC) have been investigated using Metakaolin (MK) as the cement replacing material and PVA fibers. Total twenty-seven (27) mixes of concrete have been examined with varying content of MK and PVA fibers. It has been found that the coarser type PVA fibers provide strengths competitive to control or higher than control. Concrete with coarser type PVA fibers has also refined microstructure, but the microstructure has been undergone with the increase in aspect ratio of fibers. The microstructure of concrete with MK has also more refined and packing of material is much better with MK. PVA fibers not only give higher stiffness but also showed the deflection hardening response. Toughness Index of HSDC reflects the improvement in flexural toughness over the plain concrete and the maximum toughness indices have been observed with 10% MK and 2% volume fraction of PVA fibers.

Shoulder-Rotator Strength, Range of Motion, and Acromiohumeral Distance in Asymptomatic Adolescent Volleyball Attackers.

Science.gov (United States)

Harput, Gulcan; Guney, Hande; Toprak, Ugur; Kaya, Tunca; Colakoglu, Fatma Filiz; Baltaci, Gul

2016-09-01

Sport-specific adaptations at the glenohumeral joint could occur in adolescent athletes because they start participating in high-performance sports in early childhood. To investigate shoulder-rotator strength, internal-rotation (IR) and external-rotation (ER) range of motion (ROM), and acromiohumeral distance (AHD) in asymptomatic adolescent volleyball attackers to determine if they have risk factors for injury. Cross-sectional study. University laboratory. Thirty-nine adolescent high school-aged volleyball attackers (22 boys, 17 girls; age = 16.0 ± 1.4 years, height = 179.2 ± 9.0 cm, mass = 67.1 ± 10.9 kg, body mass index = 20.7 ± 2.6 kg/m 2 ). Shoulder IR and ER ROM, total-rotation ROM, glenohumeral IR deficit, AHD, and concentric and eccentric strength of the shoulder internal and external rotators were tested bilaterally. External-rotation ROM was greater (t 38 = 4.92, P 18°). We observed greater concentric internal-rotator (t 38 = 2.89, P = .006) and eccentric external-rotator (t 38 = 2.65, P = .01) strength in the dominant than in the nondominant shoulder. The AHD was less in the dominant shoulder (t 38 = -3.60, P volleyball attackers demonstrated decreased IR ROM, total ROM, and AHD and increased ER ROM in their dominant shoulder. Therefore, routine screening of adolescent athletes and designing training programs for hazardous adaptive changes could be important in preventing shoulder injuries.

Strength Characteristics of Groundnut Leaf/Stem Ash (GLSA Concrete

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Oseni O. W.

2016-09-01

Full Text Available The compressive strength properties of concrete are substantial factors in the design and construction of concrete structures. Compressive strength directly affects the degree to which the concrete can be able to carry a load over time. These changes are complemented by deflections, cracks etc., in the structural elements of concrete. This research investigated the effect of groundnut leaf/stem ash (GLSA on the compressive strength of concrete at 0%, 5 %, 10 % and 15 % replacements of cement. The effect of the water-cement ratio on properties such as the compressive strength, slump, flow and workability properties of groundnut leaf/stem ash (GLSA mixes with OPC were evaluated to determine whether they are acceptable for use in concrete structural elements. A normal concrete mix with cement at 100 % (i.e., GLSA at 0% with concrete grade C25 that can attain an average strength of 25 N/mm2 at 28 days was used as a control at design water-cement ratios of 0.65 and grading of (0.5-32 mm from fine to coarse aggregates was tested for: (1 compressive strength, and the (2 slump and flow Test. The results and observations showed that the concrete mixes from GLSA at 5 – 15 % ratios exhibit: pozzolanic properties and GLSA could be used as a partial replacement for cement at these percentage mix ratios compared with the control concrete; an increase in the water-cement ratio showed a significant decrease in the compressive strength and an increase in workability. Therefore, it is important that all concrete mixes exude an acceptably designed water-cement ratio for compressive strength characteristics for use in structures, water-cement ratio is a significant factor.

Gravitational field strength and generalized Komar-integral

International Nuclear Information System (INIS)

Simon, W.

1984-01-01

We define a 'gravitational field strength' in theories of the Einstein-Cartan type admitting a Killing-vector. This field strength is a second rank, antisymmetric, divergence-free tensor, whose ('Komar-') integral over a closed 2-surface gives a physically meaningful quantity. We find conditions on the Lagrange-density of the theory which ensure the existence of such a tensor, and show that they are satisfied for N = 2-supergravity and for a special case of the bosonic sector of N = 4-supergravity. We discuss a possible application of the generalized Komar-integral in the theory of stationary black holes. We also consider the Kaluza-Klein-approach to the 'field-strength-problem', which turns out to be particularly rewarding in the application to black holes. (Author)

High strength H2S resistant steels and alloys for oil field tubular products

International Nuclear Information System (INIS)

Straatmann, J.A.; Grobner, P.J.

1976-01-01

New sources of oil and natural gas are more frequently occurring at greater depths in hostile surface and underground environments. The materials utilized in drilling and completing the wells require higher strength along with improved resistance to corrosive/embrittling attack by contaminants present in the deep, high pressure-high temperature formations. Higher strength steels having yield strengths in excess of 690 MPa and possessing improved resistance to sulfide stress corrosion cracking (SSC) have been developed and are currently being evaluated by the oil industry. The research to develop these new steels combined modifications of chemical compositions, heat treatment and processing variables. For most severe SSC environments and deep wells, it was necessary to provide even better alloys for tubular materials. The successful solution to the problem was found with the utilization of nickel-base alloys. These materials are being evaluated in commercial applications

Investigating the characteristic strength of flocs formed from crude and purified Hibiscus extracts in water treatment.

Science.gov (United States)

Jones, Alfred Ndahi; Bridgeman, John

2016-10-15

The growth, breakage and re-growth of flocs formed using crude and purified seed extracts of Okra (OK), Sabdariffa (SB) and Kenaf (KE) as coagulants and coagulant aids was assessed. The results showed floc size increased from 300 μm when aluminium sulphate (AS) was used as a coagulant to between 696 μm and 722 μm with the addition of 50 mg/l of OK, KE and SB crude samples as coagulant aids. Similarly, an increase in floc size was observed when each of the purified proteins was used as coagulant aid at doses of between 0.123 and 0.74 mg/l. The largest floc sizes of 741 μm, 460 μm and 571 μm were obtained with a 0.123 mg/l dose of purified Okra protein (POP), purified Sabdariffa (PSP) and purified Kenaf (PKP) respectively. Further coagulant aid addition from 0.123 to 0.74 mg/l resulted in a decrease in floc size and strength in POP and PSP. However, an increase in floc strength and reduced d50 size was observed in PKP at a dose of 0.74 mg/l. Flocs produced when using purified and crude extract samples as coagulant aids exhibited high recovery factors and strength. However, flocs exhibited greater recovery post-breakage when the extracts were used as a primary coagulant. It was observed that the combination of purified proteins and AS improved floc size, strength and recovery factors. Therefore, the applications of Hibiscus seeds in either crude or purified form increases floc growth, strength, recoverability and can also reduce the cost associated with the import of AS in developing countries. Crown Copyright © 2016. Published by Elsevier Ltd. All rights reserved.

Crystal growth vs. conventional acid etching: A comparative evaluation of etch patterns, penetration depths, and bond strengths

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Devanna Raghu

2008-01-01

Full Text Available The present study was undertaken to investigate the effect on enamel surface, penetration depth, and bond strength produced by 37% phosphoric acid and 20% sulfated polyacrylic acid as etching agents for direct bonding. Eighty teeth were used to study the efficacy of the etching agents on the enamel surface, penetration depth, and tensile bond strength. It was determined from the present study that a 30 sec application of 20% sulfated polyacrylic acid produced comparable etching topography with that of 37% phosphoric acid applied for 30 sec. The 37% phosphoric acid dissolves enamel to a greater extent than does the 20% sulfated polyacrylic acid. Instron Universal testing machine was used to evaluate the bond strengths of the two etching agents. Twenty percent sulfated polyacrylic acid provided adequate tensile bond strength. It was ascertained that crystal growth can be an alternative to conventional phosphoric acid etching as it dissolves lesser enamel and provides adequate tensile bond strength.

On high temperature strength of carbon steels

International Nuclear Information System (INIS)

Ichinose, Hiroyuki; Tamura, Manabu; Kanero, Takahiro; Ihara, Yoshihito

1977-01-01

In the steels for high temperature use, the oxidation resistance is regarded as important, but carbon steels show enough oxidation resistance to be used continuously at the temperature up to 500 deg. C if the strength is left out of consideration, and up to 450 deg. C even when the strength is taken into account. Moreover, the production is easy, the workability and weldability are good, and the price is cheap in carbon steels as compared with alloy steels. In the boilers for large thermal power stations, 0.15-0.30% C steels are used for reheater tubes, main feed water tubes, steam headers, wall water tubes, economizer tubes, bypass pipings and others, and they account for 70% of all steel materials used for the boilers of 350 MW class and 30% in 1000 MW class. The JIS standard for the carbon steels for high temperature use and the related standards in foreign countries are shown. The high temperature strength of carbon steels changes according to the trace elements, melting and heat treatment as well as the main compositions of C, Si and Mn. Al and N affect the high temperature strength largely. The characteristics of carbon steels after the heating for hours, the factors controlling the microstructure and high temperature strength, and the measures to improve the high temperature strength of carbon steels are explained. (Kako, I.)

Effect of organic solvents compared to sandblasting on the repair bond strength of nanohybrid and nanofilled composite resins

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Rafael Torres Brum

2017-01-01

Full Text Available Background: This study evaluated the effect of different surface treatments on the repair bond strength of nanohybrid (Empress Direct and nanofilled (Filtek Z350 XT composite resins. Materials and Methods: A total of 120 specimens of each material (7.5 x 4.5 x 3 mm were prepared and polished with SiC paper. Half of the specimens were kept in water for seven days and the other half for six months; they were then divided into six groups according to the type of surface treatment: negative control (no treatment, Al2O3sandblasted, liquid acetone, acetone gel, liquid alcohol and alcohol gel. Following application of the silane coupling agent and the adhesive system, composite resin cylinders were fabricated on the specimens and light cured (20 seconds. The same composite resins were used for the repair. Additionally, ten intact specimens of each composite resin (without repair were prepared (positive control. The specimens were then loaded to failure in the microshear mode. Three additional specimens were fabricated in each group, and the surface treatments were analyzed by atomic force microscopy, energy-dispersive X-ray spectroscopy (EDS and scanning electron microscopy (SEM. Results: The nanofilled composite resin showed higher cohesive strength and repair bond strength than the nanohybrid composite resin. The aging process affected the repair bond strength of the nanofilled composite resin. Al2O3sandblasting was more efficient for the nanofilled composite resin and promoted greater surface roughness in both materials. The solvents demonstrated higher efficacy for the nanohybrid composite resin. Conclusion: The strengths resulting from the solvents were material dependent, and Al2O3sandblasting resulted in superior repair bond strength in both materials.

Effect of 8 weeks of free-weight and machine-based strength training on strength and power performance.

Science.gov (United States)

Wirth, Klaus; Keiner, Michael; Hartmann, Hagen; Sander, Andre; Mickel, Christoph

2016-12-01

The aim of this study was to evaluate the effectiveness of free-weight and machine-based exercises to increase different strength and speed-strength variables. One hundred twenty male participants (age: 23.8 ± 2.5 years; body height: 181.0 ± 6.8 cm; body mass: 80.2 ± 8.9 kg) joined the study. The 2 experimental groups completed an 8 week periodized strength training program that included 2 training sessions per week. The exercises that were used in the strength training programs were the parallel barbell squat and the leg press. Before and after the training period, the 1-repetition-maximum in the barbell squat and the leg press, the squat jump, the countermovement jump and unilateral isometric force (maximal isometric force and the rate of force development) were evaluated. To compare each group pre vs. post-intervention, analysis of variance with repeated measures and Scheffé post-hoc tests were used. The leg press group increased their 1-repetition-maximum significantly (p squat group such variables as 1-repetition-maximum, the squat jump and the countermovement jump increased significantly (p squat group even showed a statistically significant decrease. Differences between the 2 experimental groups were detected for the squat jump and the countermovement jump. In comparison with the leg press, the squat might be a better strength training exercise for the development of jump performance.

Microcracking and durability of high strength concretes

International Nuclear Information System (INIS)

Yssorche, M.P.

1995-07-01

Durability of 28 days compressive strength concrete of 20 to 120 MPa has been studied. The ability of concrete to transport aggressive agents has been determined for four properties: the air permeability, the chloride diffusivity, the water absorption and the carbonation. A chloride migration test for high and very high strength concrete (HSC and VHSC) has been built. The relationship between transport properties and the compressive strength after one and 28 days of humid curing has always the same shape: transport decreases when strength increases. However, transport properties often vary in the ordinary concrete field. Beyond, the domain is much more limited. The relationship between transport properties and strength valid for ordinary concrete can not be simply extrapolated for HSC and VHSC. To determine the part of microcracking of HSC and VHSC, concrete behaviour stored in two mediums has been studied: the ones shaming the storing condition of concrete in auto-desiccation, the others reproducing the storing conditions of concrete in desiccation. Auto-desiccation (measuring relative humidity at balance) and desiccation (measuring mass losses) have been showed. Microcracks and shrinkage strains have been measured. It has been showed that auto-desiccation microcracks proving in HSC or VHSC don't question the durability. Microcracks, as for permeability, do not develop between 28 days and one year. On the contrary, desiccation microcracks observed in HSC and VHSC, increase with transport properties between 28 days and 1.5 year. Thus, a bulk concrete is always more durable than a cover concrete. At last, the good influence of increase of curing of 1 to 28 days on the transport of all concretes has been emphasized. (author)

Bond strength of orthodontic light-cured resin-modified glass ionomer cement.

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Cheng, Hsiang Yu; Chen, Chien Hsiu; Li, Chuan Li; Tsai, Hung Huey; Chou, Ta Hsiung; Wang, Wei Nan

2011-04-01

The purpose of this study was to compare the bond strengths and debonded interfaces achieved with light-cured resin-modified glass ionomer cement (RMGIC) and conventional light-cured composite resin. In addition, the effects of acid etching and water contamination were examined. One hundred human premolars were randomly divided into five equal groups. The mini Dyna-lock upper premolar bracket was selected for testing. The first four groups were treated with light-cured RMGIC with or without 15 per cent phosphoric acid-etching treatment and with or without water contamination preceding bracket bonding. The control samples were treated with the conventional light-cured Transbond composite resin under acid etching and without water contamination. Subsequently, the brackets were debonded by tensile force using an Instron machine. The modified adhesive remnant index (ARI) scores were assigned to the bracket base of the debonded interfaces using a scanning electron microscope. The bond strength and modified ARI scores were determined and analysed statistically by one-way analysis of variance and chi-square test. Under all four conditions, the bond strength of the light-cure RMGIC was equal to or higher than that of the conventional composite resin. The highest bond strength was achieved when using RMGIC with acid etching but without water contamination. The modified ARI scores were 2 for Fuji Ortho LC and 3 for Transbond. No enamel detachment was found in any group. Fifteen per cent phosphoric acid etching without moistening the enamel of Fuji Ortho LC provided the more favourable bond strength. Enamel surfaces, with or without water contamination and with or without acid etching, had the same or a greater bond strength than Transbond.

Peel strength of LDPE/ethylene-1-butene copolymer film crosslinked by radiation

International Nuclear Information System (INIS)

Nho, Young Chang; Kim, Jeong Il; Kang, Phil Hyun

2003-01-01

In this study, ethylene-1-butene copolymer(EBP) was blended with LDPE to improve the mechanical properties as the packaging materials. After they were irradiated by an electron beam, their physical properties such as tensile strength, elongation, modulus, peel strength, DSC, and DMA were examined. The results showed that the addition of EBP to LDPE exerted significant effects on the mechanical properties such as the tensile strength and peel strength. The addition of EBP led to a maximum increase in peel strength of ∼ 430%. The addition of 10-25w% EBP in LDPE was sufficient to enhance the peel strength significantly

Fat Mass Is Positively Associated with Estimated Hip Bone Strength among Chinese Men Aged 50 Years and above with Low Levels of Lean Mass

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Guiyuan Han

2017-04-01

Full Text Available This study investigated the relationships of fat mass (FM and lean mass (LM with estimated hip bone strength in Chinese men aged 50–80 years (median value: 62.0 years. A cross-sectional study including 889 men was conducted in Guangzhou, China. Body composition and hip bone parameters were generated by dual-energy X-ray absorptiometry (DXA. The relationships of the LM index (LMI and the FM index (FMI with bone phenotypes were detected by generalised additive models and multiple linear regression. The associations between the FMI and the bone variables in LMI tertiles were further analysed. The FMI possessed a linear relationship with greater estimated hip bone strength after adjustment for the potential confounders (p < 0.05. Linear relationships were also observed for the LMI with most bone phenotypes, except for the cross-sectional area (p < 0.05. The contribution of the LMI (4.0%–12.8% was greater than that of the FMI (2.0%–5.7%. The associations between the FMI and bone phenotypes became weaker after controlling for LMI. Further analyses showed that estimated bone strength ascended with FMI in the lowest LMI tertile (p < 0.05, but not in the subgroups with a higher LMI. This study suggested that LM played a critical role in bone health in middle-aged and elderly Chinese men, and that the maintenance of adequate FM could help to promote bone acquisition in relatively thin men.

Greater happiness for a greater number: Is that possible? If so how? (Arabic)

NARCIS (Netherlands)

R. Veenhoven (Ruut); E. Samuel (Emad)

2012-01-01

textabstractWhat is the final goal of public policy? Jeremy Bentham (1789) would say: greater happiness for a greater number. He thought of happiness as subjective enjoyment of life; in his words as “the sum of pleasures and pains”. In his time, the happiness of the great number could not be

Bonding Properties of Basalt Fiber and Strength Reduction According to Fiber Orientation

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Jeong-Il Choi

2015-09-01

Full Text Available The basalt fiber is a promising reinforcing fiber because it has a relatively higher tensile strength and a density similar to that of a concrete matrix as well as no corrosion possibility. This study investigated experimentally the bonding properties of basalt fiber with cementitious material as well as the effect of fiber orientation on the tensile strength of basalt fiber for evaluating basalt fiber’s suitability as a reinforcing fiber. Single fiber pullout tests were performed and then the tensile strength of fiber was measured according to fiber orientation. The test results showed that basalt fiber has a strong chemical bond with the cementitious matrix, 1.88 times higher than that of polyvinyl alcohol fibers with it. However, other properties of basalt fiber such as slip-hardening coefficient and strength reduction coefficient were worse than PVA and polyethylene fibers in terms of fiber bridging capacity. Theoretical fiber-bridging curves showed that the basalt fiber reinforcing system has a higher cracking strength than the PVA fiber reinforcing system, but the reinforcing system showed softening behavior after cracking.

Bonding Properties of Basalt Fiber and Strength Reduction According to Fiber Orientation.

Science.gov (United States)

Choi, Jeong-Il; Lee, Bang Yeon

2015-09-30

The basalt fiber is a promising reinforcing fiber because it has a relatively higher tensile strength and a density similar to that of a concrete matrix as well as no corrosion possibility. This study investigated experimentally the bonding properties of basalt fiber with cementitious material as well as the effect of fiber orientation on the tensile strength of basalt fiber for evaluating basalt fiber's suitability as a reinforcing fiber. Single fiber pullout tests were performed and then the tensile strength of fiber was measured according to fiber orientation. The test results showed that basalt fiber has a strong chemical bond with the cementitious matrix, 1.88 times higher than that of polyvinyl alcohol fibers with it. However, other properties of basalt fiber such as slip-hardening coefficient and strength reduction coefficient were worse than PVA and polyethylene fibers in terms of fiber bridging capacity. Theoretical fiber-bridging curves showed that the basalt fiber reinforcing system has a higher cracking strength than the PVA fiber reinforcing system, but the reinforcing system showed softening behavior after cracking.

Eccentric Knee Flexor Strength and Risk of Hamstring Injuries in Rugby Union: A Prospective Study.

Science.gov (United States)

Bourne, Matthew N; Opar, David A; Williams, Morgan D; Shield, Anthony J

2015-11-01

Hamstring strain injuries (HSIs) represent the most common cause of lost playing time in rugby union. Eccentric knee flexor weakness and between-limb imbalance in eccentric knee flexor strength are associated with a heightened risk of HSIs in other sports; however, these variables have not been explored in rugby union. To determine if lower levels of eccentric knee flexor strength or greater between-limb imbalance in this parameter during the Nordic hamstring exercise are risk factors for HSIs in rugby union. Cohort study; Level of evidence, 2. This prospective study was conducted over the 2014 Super Rugby and Queensland Rugby Union seasons. In total, 178 rugby union players (mean age, 22.6 ± 3.8 years; mean height, 185.0 ± 6.8 cm; mean weight, 96.5 ± 13.1 kg) had their eccentric knee flexor strength assessed using a custom-made device during the preseason. Reports of previous hamstring, quadriceps, groin, calf, and anterior cruciate ligament injuries were also obtained. The main outcome measure was the prospective occurrence of HSIs. Twenty players suffered at least 1 HSI during the study period. Players with a history of HSIs had a 4.1-fold (95% CI, 1.9-8.9; P = .001) greater risk of subsequent HSIs than players without such a history. Between-limb imbalance in eccentric knee flexor strength of ≥15% and ≥20% increased the risk of HSIs by 2.4-fold (95% CI, 1.1-5.5; P = .033) and 3.4-fold (95% CI, 1.5-7.6; P = .003), respectively. Lower eccentric knee flexor strength and other prior injuries were not associated with an increased risk of future HSIs. Multivariate logistic regression revealed that the risk of reinjuries was augmented in players with strength imbalances. Previous HSIs and between-limb imbalance in eccentric knee flexor strength were associated with an increased risk of future HSIs in rugby union. These results support the rationale for reducing imbalance, particularly in players who have suffered a prior HSI, to mitigate the risk of future

Show us the money: lessons in transparency from state pharmaceutical marketing disclosure laws.

Science.gov (United States)

Chimonas, Susan; Rozario, Natassia M; Rothman, David J

2010-02-01

To assess legislation requiring drug companies to report gifts to providers, and to evaluate the information obtained. Data included legislation in Vermont, Minnesota, Maine, Massachusetts, West Virginia, and the District of Columbia, and company disclosure data from Vermont. We evaluated the strengths and weaknesses of state legislation. We also analyzed 4 years of company disclosures from Vermont, assessing the value and distribution of industry-provider exchanges and identifying emerging trends in companies' practices. State legislation is publically available. We obtained Vermont's data through requests to the state's Attorney General's office. Of the state laws, only Vermont's yielded robust, publically available data. These data show gifting was dominated by a few major corporations, and Companies were especially generous to specialists in psychiatry, endocrinology/diabetes/metabolism, internal medicine, and neurology. Companies increasingly used loopholes in the law to avoid public scrutiny. Disclosure laws are an important first step in bringing greater transparency to physician-industry relationships. But flaws and weaknesses limit the states' ability to render physician-industry exchanges fully transparent. Future efforts should build on these lessons to render physician-industry relationships fully transparent.

SHOULDER EXTERNAL ROTATOR STRENGTH IN RESPONSE TO VARIOUS SITTING POSTURES: A CONTROLLED LABORATORY STUDY.

Science.gov (United States)

Pheasant, Steven; Haydt, Richard; Gottstein, Thomas; Grasso, Anthony; Lombard, Nicholas; Stone, Brandon

2018-02-01

The forward head rounded shoulder (FHRS) sitting posture has been associated with decreased shoulder complex muscle strength and function. Upon clinical observation, the adverse effects of the FHRS sitting posture on shoulder complex isometric muscle strength is also present when testing controls for scapular position. The purpose of the study was to assess the effect of various sitting postures on shoulder external rotator muscle isometric strength when the strength testing controls for scapular position. A cohort study, with subjects serving as their own controls. One hundred subjects ages 20-26 participated in the study. Each subject was placed in a neutral cervical sitting (NCS) posture which was maintained for five minutes after which the strength of the dominant shoulder external rotators was immediately tested with the glenohumeral joint in the neutral position using a Micro-FET3 Hand Held Muscle Testing Dynamometer (HHMTD). Each subject was returned to the NCS posture for subsequent external rotator strength testing after five minutes in a FHRS sitting posture, five additional minutes in the NCS posture and five minutes in a retracted cervical sitting (RCS) posture resulting in each subjects' external rotator strength being tested on four occasions. Subjects were randomized for order between the FHRS and RCS postures. Mean strength values for each condition were normalized to the mean strength value for the 1 st NCS condition for each subject. A statistically significant decline in shoulder external rotator strength following the FHRS sitting posture occurred compared to the appropriate postural conditions (pexternal rotator strength following five minutes in the FHRS sitting posture. The average percentage of strength decline in those with greater than a 10% reduction in external rotator strength was 19%. Sixty-four percent of the subjects experienced less than a 10% decline in shoulder external rotator strength in response to the FHRS sitting posture

Strength training and physical activity in boys: a randomized trial.

Science.gov (United States)

Meinhardt, Udo; Witassek, Fabienne; Petrò, Renato; Fritz, Chris; Eiholzer, Urs

2013-12-01

In developed societies levels of daily physical activity (PA) among school-age children are decreasing. This implies risk factors for cardiovascular and metabolic diseases. Specific strategies to improve levels of PA are needed. In prepubertal boys there is evidence that strength training increases spontaneous PA outside of training. A total of 102 schoolchildren (age 10-14 years) in Switzerland were randomly assigned to physical education classes or to participate twice weekly at a guided strength training program for 19 weeks. Spontaneous PA energy expenditure (PAEE; 3axial accelerometry for 7 days), leg and arm strength, and body composition (dual energy radiograph absorptiometry) were measured at baseline, after 19 weeks of training intervention, and after 3 months of washout. There were no significant differences between the groups at baseline. In the intervention group, PAEE increased by 10% from baseline to end of training in boys (P = .02), but not in girls. Leg and arm strength were increased owing to training intervention in both boys and girls. All other variables were unchanged. Baseline PAEE was significantly negatively correlated with changes of PAEE. Targeted strength training significantly increases daily spontaneous PA behavior in boys. The less active children showed the greatest increase in spontaneous PAEE. Girls showed a similar increase in strength, but not in spontaneous PAEE. This may be explained by their earlier pubertal development. Strength training may be a promising strategy in schools to counteract decreasing levels of PA.

Estimated strength of shear keys in concrete dams

Energy Technology Data Exchange (ETDEWEB)

Curtis, D.D. [Hatch Energy, Niagara Falls, ON (Canada); Lum, K.K.Y. [BC Hydro, Burnaby, BC (Canada)

2008-07-01

BC Hydro requested that Hatch Energy review the seismic stability of Ruskin Dam which was constructed in 1930 at Hayward Lake in British Columbia. The concrete gravity dam is founded nearly entirely on rock in a narrow valley. The vertical joints between blocks are keyed and grouted. The strength of the shear keys was assessed when a non-linear finite element model found that significant forces were being transferred laterally to the abutments during an earthquake. The lateral transfer of loads to the abutment relies on the strength of the shear keys. The dynamic finite element analysis was used to determine the stability of the dam. A review of the shear strength measurements reported in literature showed that the measurements compared well to those obtained by BC Hydro from cores taken from Ruskin Dam. The cohesive strength obtained using the Griffith failure criteria was also in good agreement with both sets of measurements. A simple ultimate shear strength equation was developed using the Mohr-Coulomb failure criteria to determine combined cohesive and frictional strength of shear keys. Safety factors of 2.0 for static loads and 1.5 for seismic loads were proposed to reduce the ultimate strength to allowable values. It was concluded that given the relatively high shear strength established for the shear keys, the abutment rock or dam/abutment contact will control the amount of load which can arch to the abutments. 8 refs., 4 tabs., 5 figs.

Give Me Strength.

Institute of Scientific and Technical Information of China (English)

维拉

1996-01-01

Mort had an absolutely terrible day at the office.Everythingthat could go wrong did go wrong.As he walked home he could beheard muttering strange words to himself:“Oh,give me strength,give me strength.”Mort isn’t asking for the kind of strength thatbuilds strong muscles:he’s asking for the courage or ability to

An Invitro Comparative Evaluation of Compressive Strength and Antibacterial Activity of Conventional GIC and Hydroxyapatite Reinforced GIC in Different Storage Media.

Science.gov (United States)

Bali, Praveen; Prabhakar, Attiguppe Ramasetty; Basappa, Nadig

2015-07-01

GIC is the most commonly used restorative material in pediatric dentistry since it has got various advantages like fluoride release, anticariogenic property and chemical adhesion to tooth but a major disadvantage is its contraindication in posterior teeth because of poor mechanical properties. The purpose of this study is a modest attempt to explore the influence of the addition of 8% hydroxyapatite to conventional GIC on its compressive strength when immersed in different storage media and antibacterial activity. One hundred and twenty six pellets of the specific dimension of 6 x 4 mm were prepared and divided into 6 groups and were immersed in deionized water, artificial saliva, lactic acid solution respectively for three hours everyday over 30 days test period. The compressive strength was measured by using a universal testing machine (AG-50kNG) at cross head of 1mm(2)/min and strength was determined after 1 day, 7 days, 30 days respectively and the antibacterial activity evaluated against Streptococcus mutans strain in brain heart infusion broth using serial dilution method. Group wise comparisons were made by one-way ANOVA followed by post-hoc Tukey's test, Intergroup comparison was done with Mann-Whitney test. GIC±HAp showed significantly greater antibacterial activity against Streptococcus mutans when compared to GIC group. There was no statistically significant change in the compressive strength among the groups except for group 3 and group 6 when immersed in lactic acid had shown significant difference at the end of 24 hours. The addition of 8% hydroxyapatite to GIC showed marked increased in the antibacterial activity of the conventional GIC against caries initiating organism without much increase in the compressive strength of the GIC when immersed in the different storage media.

Self-Control Strength Depletion Reduces Self-Efficacy and Impairs Exercise Performance.

Science.gov (United States)

Graham, Jeffrey D; Bray, Steven R

2015-10-01

The purpose of this study was to investigate the role of task self-efficacy as a psychological factor involved in the relationship between self-control depletion and physical endurance. Participants (N = 37) completed two isometric handgrip endurance trials, separated by a Stroop task, which was either congruent (control) or incongruent (causing depletion). Task self-efficacy for the second endurance trial was measured following the Stroop task. Participants in the depletion condition reported lower task self-efficacy and showed a greater reduction in performance on the second endurance trial when compared with controls. Task self-efficacy also mediated the relationship between self-control depletion and endurance performance. The results of this study provide evidence that task self-efficacy is negatively affected following self-control depletion. We recommend that task self-efficacy be further investigated as a psychological factor accounting for the negative change in self-control performance of physical endurance and sport tasks following self-control strength depletion.

Effects of Sprint Interval Training With Active Recovery vs. Endurance Training on Aerobic and Anaerobic Power, Muscular Strength, and Sprint Ability.

Science.gov (United States)

Sökmen, Bülent; Witchey, Ronald L; Adams, Gene M; Beam, William C

2018-03-01

Sökmen, B, Witchey, RL, Adams, GM, and Beam, WC. Effects of sprint interval training with active recovery vs. endurance training on aerobic and anaerobic power, muscular strength, and sprint ability. J Strength Cond Res 32(3): 624-631, 2018-This study compared sprint interval training with active recovery (SITAR) to moderate-intensity endurance training (ET) in aerobic and anaerobic power, muscular strength, and sprint time results. Forty-two recreationally active adults were randomly assigned to a SITAR or ET group. Both groups trained 3× per week for 10 weeks at 75% of V[Combining Dot Above]O2max for 30 minutes weeks 1-4, with duration increasing to 35 minutes weeks 5-7 and 40 minutes weeks 8-10. While ET ran on a 400-m track without rest for the full training session, SITAR sprinted until the 200-m mark and recovered with fast walking or light jogging the second 200 m to the finish line in 3× original sprint time. Maximal oxygen consumption (V[Combining Dot Above]O2max), anaerobic treadmill run to exhaustion at 12.5 km·h at 20% incline, isokinetic leg extension and flexion strength at 60 and 300°·s, and 50 m sprint time were determined before and after training. Results showed a significant improvement (p ≤ 0.05) in absolute and relative V[Combining Dot Above]O2max, anaerobic treadmill run, and sprint time in both groups. Only SITAR showed significant improvements in isokinetic leg extension and flexion at 300°·s and decreases in body mass (p ≤ 0.05). SITAR also showed significantly greater improvement (p ≤ 0.05) over ET in anaerobic treadmill run and 50 m sprint time. These data suggest that SITAR is a time-efficient strategy to induce rapid adaptations in V[Combining Dot Above]O2max comparable to ET with added improvements in anaerobic power, isokinetic strength, and sprint time not observed with ET.

The Association between Maximal Bench Press Strength and Isometric Handgrip Strength among Breast Cancer Survivors

Science.gov (United States)

Rogers, Benjamin H.; Brown, Justin C.; Gater, David R.; Schmitz, Kathryn H.

2016-01-01

Objective One-repetition maximum (1-RM) bench press strength is considered the gold standard to quantify upper-body muscular strength. Isometric handgrip strength is frequently used as a surrogate for 1-RM bench press strength among breast cancer (BrCa) survivors. The relationship between 1-RM bench press strength and isometric handgrip strength, however, has not been characterized among BrCa survivors. Design Cross-sectional study. Setting Laboratory. Participants Community-dwelling BrCa survivors. Interventions Not applicable. Main Outcome Measure 1-RM bench press strength was measured with a barbell and exercise bench. Isometric handgrip strength was measured using an isometric dynamometer with three maximal contractions of left and right hands. All measures were conducted by staff with training in clinical exercise testing. Results Among 295 BrCa survivors, 1-RM bench press strength was 18.2±6.1 kg (range: 2.2-43.0) and isometric handgrip strength was 23.5±5.8 kg (range: 9.0-43.0). The strongest correlate of 1-RM bench press strength was the average isometric handgrip strength of both hands (r=0.399; Pisometric handgrip strength of both hands overestimated 1-RM bench press strength by 4.7 kg (95% limits of agreement: −8.2 to 17.6). In a multivariable linear regression model, the average isometric handgrip strength of both hands (β=0.31; Pstrength (R2=0.23). Conclusions Isometric handgrip strength is a poor surrogate for 1-RM bench press strength among BrCa survivors. 1-RM bench press and isometric handgrip strength quantify distinct components of muscular strength. PMID:27543047

Strength Development of High-Strength Ductile Concrete Incorporating Metakaolin and PVA Fibers

Directory of Open Access Journals (Sweden)

Muhammad Fadhil Nuruddin

2014-01-01

Full Text Available The mechanical properties of high-strength ductile concrete (HSDC have been investigated using Metakaolin (MK as the cement replacing material and PVA fibers. Total twenty-seven (27 mixes of concrete have been examined with varying content of MK and PVA fibers. It has been found that the coarser type PVA fibers provide strengths competitive to control or higher than control. Concrete with coarser type PVA fibers has also refined microstructure, but the microstructure has been undergone with the increase in aspect ratio of fibers. The microstructure of concrete with MK has also more refined and packing of material is much better with MK. PVA fibers not only give higher stiffness but also showed the deflection hardening response. Toughness Index of HSDC reflects the improvement in flexural toughness over the plain concrete and the maximum toughness indices have been observed with 10% MK and 2% volume fraction of PVA fibers.

Reactive Strength Index: A Poor Indicator of Reactive Strength?

Science.gov (United States)

Healy, Robin; Kenny, Ian; Harrison, Drew

2017-11-28

The primary aim was to assess the relationships between reactive strength measures and associated kinematic and kinetic performance variables achieved during drop jumps. A secondary aim was to highlight issues with the use of reactive strength measures as performance indicators. Twenty eight national and international level sprinters, consisting of fourteen men and women, participated in this cross-sectional analysis. Athletes performed drop jumps from a 0.3 m box onto a force platform with dependent variables contact time (CT), landing time (TLand), push-off time (TPush), flight time (FT), jump height (JH), reactive strength index (RSI, calculated as JH / CT), reactive strength ratio (RSR, calculated as FT / CT) and vertical leg spring stiffness (Kvert) recorded. Pearson's correlation test found very high to near perfect relationships between RSI and RSR (r = 0.91 to 0.97), with mixed relationships found between RSI, RSR and the key performance variables, (Men: r = -0.86 to -0.71 between RSI/RSR and CT, r = 0.80 to 0.92 between RSI/RSR and JH; Women: r = -0.85 to -0.56 between RSR and CT, r = 0.71 between RSI and JH). This study demonstrates that the method of assessing reactive strength (RSI versus RSR) may be influenced by the performance strategies adopted i.e. whether an athlete achieves their best reactive strength scores via low CTs, high JHs or a combination. Coaches are advised to limit the variability in performance strategies by implementing upper and / or lower CT thresholds to accurately compare performances between individuals.

Flexural strength and the probability of failure of cold isostatic pressed zirconia core ceramics.

Science.gov (United States)

Siarampi, Eleni; Kontonasaki, Eleana; Papadopoulou, Lambrini; Kantiranis, Nikolaos; Zorba, Triantafillia; Paraskevopoulos, Konstantinos M; Koidis, Petros

2012-08-01

The flexural strength of zirconia core ceramics must predictably withstand the high stresses developed during oral function. The in-depth interpretation of strength parameters and the probability of failure during clinical performance could assist the clinician in selecting the optimum materials while planning treatment. The purpose of this study was to evaluate the flexural strength based on survival probability and Weibull statistical analysis of 2 zirconia cores for ceramic restorations. Twenty bar-shaped specimens were milled from 2 core ceramics, IPS e.max ZirCAD and Wieland ZENO Zr, and were loaded until fracture according to ISO 6872 (3-point bending test). An independent samples t test was used to assess significant differences of fracture strength (α=.05). Weibull statistical analysis of the flexural strength data provided 2 parameter estimates: Weibull modulus (m) and characteristic strength (σ(0)). The fractured surfaces of the specimens were evaluated by scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). The investigation of the crystallographic state of the materials was performed with x-ray diffraction analysis (XRD) and Fourier transform infrared (FTIR) spectroscopy. Higher mean flexural strength (Plines zones). Both groups primarily sustained the tetragonal phase of zirconia and a negligible amount of the monoclinic phase. Although both zirconia ceramics presented similar fractographic and crystallographic properties, the higher flexural strength of WZ ceramics was associated with a lower m and more voids in their microstructure. These findings suggest a greater scattering of strength values and a flaw distribution that are expected to increase failure probability. Copyright © 2012 The Editorial Council of the Journal of Prosthetic Dentistry. Published by Mosby, Inc. All rights reserved.

The effect of pretreatment with fluoride on the tensile strength of orthodontic bonding

International Nuclear Information System (INIS)

Wang, W.N.; Sheen, D.H.

1991-01-01

White spot decalcifications and caries occurring adjacent to bonded orthodontic brackets have long been a concern to orthodontists. One procedure suggested to overcome this problem is fluoride treatment prior to bonding. The purpose of this study was to compare the tensile bond strength of orthodontic self-cured resin from Concise on teeth rinsed 4 minutes in 1.23% APF with untreated controls. Measurements were made on an Instron machine. Debonding interfaces were observed with a scanning electron microscope and energy dispersive x-ray spectrometry. Distributions were calculated. The tensile bond strengths of the fluoride-treated teeth and the untreated teeth were not significantly different. The debonding interfaces between resin and bracket base, within the resin itself, and between enamel and resin were similar in the two experimental groups. However, greater enamel detachment was seen within the fluoride pretreatment group. So while fluoride pretreatment does not significantly affect tensile bond strength, it may cause enamel detachment after debonding

A dependent stress-strength interference model based on mixed copula function

Energy Technology Data Exchange (ETDEWEB)

Gao, Jian Xiong; An, Zong Wen; Liu, Bo [School of Mechatronics Engineering, Lanzhou University of Technology, Lanzhou (China)

2016-10-15

In the traditional Stress-strength interference (SSI) model, stress and strength must satisfy the basic assumption of mutual independence. However, a complex dependence between stress and strength exists in practical engineering. To evaluate structural reliability under the case that stress and strength are dependent, a mixed copula function is introduced to a new dependent SSI model. This model can fully characterize the dependence between stress and strength. The residual square sum method and genetic algorithm are also used to estimate the unknown parameters of the model. Finally, the validity of the proposed model is demonstrated via a practical case. Results show that traditional SSI model ignoring the dependence between stress and strength more easily overestimates product reliability than the new dependent SSI model.

Increasing Lean Mass and Strength: A Comparison of High Frequency Strength Training to Lower Frequency Strength Training.

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Thomas, Michael H; Burns, Steve P

The purpose of this study was to determine the effect strength training frequency has on improvements in lean mass and strength. Participants were 7 women and 12 men, age ( χ̄ = 34.64 years ± 6.91 years), with strength training experience, training age ( χ̄ = 51.16 months ± 39.02 months). Participants were assigned to one of two groups to equal baseline group demographics. High frequency training group (HFT) trained each muscle group as the agonist, 3 times per week, exercising with 3 sets per muscle group per session (3 total body workouts). Low frequency training group (LFT) trained each muscle group as the agonist one time per week, completing all 9 sets during that one workout. LFT consisted of a routine split over three days: 1) pectoralis, deltoids, and triceps; 2) upper back and biceps; 3) quadriceps, hamstrings, calves, and abdominals. Following eight weeks of training, HFT increased lean mass by 1.06 kg ± 1.78 kg, (1.9%), and LFT increased lean mass by .99 kg ± 1.31 kg, (2.0%). HFT strength improvements on the chest press was 9.07 kg ± 6.33 kg, (11%), and hack squat 20.16 kg ± 11.59 kg, (21%). LFT strength improvements on chest press was 5.80kg ± 4.26 kg, (7.0%), and hack squat 21.83 kg ± 11.17 kg, (24 %). No mean differences between groups were significant. These results suggest that HFT and LFT of equal set totals result in similar improvements in lean mass and strength, following 8 weeks of strength training.

Effects of 12-week concurrent high-intensity interval strength and endurance training programme on physical performance in healthy older people.

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García-Pinillos, Felipe; Laredo-Aguilera, José A; Muñoz-Jiménez, Marcos; Latorre-Román, Pedro A

2017-03-13

This study aimed to analyse the effect of 12-week low-volume HIIT-based concurrent training programme on body composition, upper- and lower-body muscle strength, mobility and balance in older adults, as well as to compare it with a low- moderate-intensity continuous training. 90 active older adults were randomly assigned to experimental (EG, n=47), and control (CG, n=43) groups. Body composition and physical functioning were assessed before (pre-test) and after (post-test) a 12-week intervention. A 2-way repeated measures ANOVA was used to test for an interaction between training programme and groups. The time x group interaction revealed no significant between-group differences at pre-test (p≥0.05). The group x time interaction showed significant improvements for the EG in body composition parameters (ptraining programme led to greater improvements in body composition, muscle strength, mobility and balance in healthy older people than a regular low- moderate-intensity continuous training, despite the reduction in overall training volume.

The Effects of Industrial Protective Gloves and Hand Skin Temperatures on Hand Grip Strength and Discomfort Rating.

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Ramadan, Mohamed Z

2017-12-04

Daily working activities and functions require a high contribution of hand and forearm muscles in executing grip force. To study the effects of wearing different gloves on grip strength, under a variety of hand skin temperatures, an assessment of the maximum grip strength was performed with 32 healthy male workers with a mean age (standard deviation) of 30.44 (5.35) years wearing five industrial gloves at three hand skin temperatures. Their ages and anthropometric characteristics including body mass index (BMI), hand length, hand width, hand depth, hand palm, and wrist circumference were measured. The hand was exposed to different bath temperatures (5 °C, 25 °C, and 45 °C) and hand grip strength was measured using a Jamar hydraulic hand dynamometer with and without wearing the gloves (chemical protection glove, rubber insulating glove, anti-vibration impact glove, cotton yarn knitted glove, and RY-WG002 working glove). The data were analyzed using the Shapiro-Wilk test, Pearson correlation coefficient, Tukey test, and analysis of variance (ANOVA) of the within-subject design analysis. The results showed that wearing gloves significantly affected the maximum grip strength. Wearing the RY-WG002 working glove produced a greater reduction on the maximum grip when compared with the bare hand, while low temperatures (5 °C) had a significant influence on grip when compared to medium (25 °C) and high (45 °C) hand skin temperatures. In addition, participants felt more discomfort in both environmental extreme conditions. Furthermore, they reported more discomfort while wearing neoprene, rubber, and RY-WG002 working gloves.

The Relationship Between Hip Strength and the Y-Balance Test.

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Wilson, Benjamin R; Robertson, Kaley E; Burnham, Jeremy M; Yonz, Michael C; Ireland, Mary Lloyd; Noehren, Brian

2017-07-17

The Y-Balance Test was developed as a test of dynamic postural control and has been shown to be predictive of lower extremity injury. However, the relationship between hip strength and performance on the Y-Balance Test has not been fully elucidated. The goal of this study was to identify the relationship between components of isometric hip strength and the Y-Balance Test, to provide clinicians better guidance as to specific areas of muscle performance to address in the event of poor performance on the Y-Balance Test. Laboratory Study. Biomechanics Laboratory. Seventy-three healthy participants, 40 males and 33 females, volunteered for this study. None. Participants completed the Y-Balance Test on the right leg. We then measured peak isometric torque in hip external rotation, abduction, and extension. Correlations were calculated between torque measurements, normalized for mass, and Y-Balance Test performance. Significant relationships were used in linear regression models to determine which variables were predictive of the Y-Balance Test performance. We found significant positive correlations between Y-Balance Test performance and hip abduction strength. We also found correlations between the Y-Balance Test and hip extension and external rotation strengths. Linear regression analysis showed hip abduction to be the only significant predictor of Y- Balance performance. We found the strongest association between the Y-Balance Test and hip abduction strength. We also showed smaller but significant associations with hip extension and external rotation strength. When entered into a linear regression analysis, hip abduction strength was the only significant predictor of Y-Balance performance. Using this information, practitioners should look to hip abduction strength when patients exhibit deficits in the Y-Balance Test.

Evaluation of creep rupture property of high strength ferritic/martensitic steel (PNC-FMS)

International Nuclear Information System (INIS)

Uehira, Akihiro; Mizuno, Tomoyasu; Ukai, Shigeharu; Yoshida, Eiichi

1999-04-01

High Strength Ferritic/Martensitic Steel (PNC-FMS : 11Cr-0.5Mo-2W,Nb,V), developed by JNC, is one of the candidate materials for the long-life core of large-scale fast breeder reactor. The material design base standard (tentative) of PNC-FMS was established and the creep rupture strength reduction factor in the standard was determined in 1992. This factor was based on only evaluation of decarburization effect on tensile strength after sodium exposure. In this study, creep rupture properties of PNC-FMS under out of pile sodium exposure and in pile were evaluated, using recent test results as well as previous ones. The evaluation results are summarized as follows : a. Decarburization rate constant of pressurized tubes under sodium exposure is identical with stress free specimens. b. In case of the same decarburization content under out of pile sodium exposure, creep strength tends to decrease more significantly than tensile strength. c. Creep strength under out of pile sodium exposure showed significant decrease in high temperature and long exposure time, but in pile (MOTA) creep strength showed little decrease. A new creep rupture strength reduction factor, which is the ratio of creep rupture strength under sodium exposure or in pile to in air, was made by correlating the creep rupture strength. This new method directly using the ratio of creep rupture strength was evaluated and discussed from the viewpoint of design applicability, compared with the conventional method based on decarburization effect on tensile strength. (author)

Effects of conventional welding and laser welding on the tensile strength, ultimate tensile strength and surface characteristics of two cobalt-chromium alloys: a comparative study.

Science.gov (United States)

Madhan Kumar, Seenivasan; Sethumadhava, Jayesh Raghavendra; Anand Kumar, Vaidyanathan; Manita, Grover

2012-06-01

The purpose of this study was to evaluate the efficacy of laser welding and conventional welding on the tensile strength and ultimate tensile strength of the cobalt-chromium alloy. Samples were prepared with two commercially available cobalt-chromium alloys (Wironium plus and Diadur alloy). The samples were sectioned and the broken fragments were joined using Conventional and Laser welding techniques. The welded joints were subjected to tensile and ultimate tensile strength testing; and scanning electron microscope to evaluate the surface characteristics at the welded site. Both on laser welding as well as on conventional welding technique, Diadur alloy samples showed lesser values when tested for tensile and ultimate tensile strength when compared to Wironium alloy samples. Under the scanning electron microscope, the laser welded joints show uniform welding and continuous molt pool all over the surface with less porosity than the conventionally welded joints. Laser welding is an advantageous method of connecting or repairing cast metal prosthetic frameworks.

Bone microarchitecture and estimated bone strength in men with active acromegaly.

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Silva, Paula P B; Amlashi, Fatemeh G; Yu, Elaine W; Pulaski-Liebert, Karen J; Gerweck, Anu V; Fazeli, Pouneh K; Lawson, Elizabeth; Nachtigall, Lisa B; Biller, Beverly M K; Miller, Karen K; Klibanski, Anne; Bouxsein, Mary; Tritos, Nicholas A

2017-11-01

Both acromegaly and adult growth hormone deficiency (GHD) are associated with increased fracture risk. Sufficient data are lacking regarding cortical bone microarchitecture and bone strength, as assessed by microfinite element analysis (µFEA). To elucidate both cortical and trabecular bone microarchitecture and estimated bone strength in men with active acromegaly or GHD compared to healthy controls. Cross-sectional study at a clinical research center, including 48 men (16 with acromegaly, 16 with GHD and 16 healthy controls). Areal bone mineral density (aBMD), cortical and trabecular bone microarchitecture and estimated bone strength (µFEA) at the radius and tibia. aBMD was not different between the 3 groups at any skeletal site. At the radius, patients with acromegaly had greater cortical area ( P  acromegaly had lower trabecular bone density ( P  = 0.0082), but no differences in cortical bone microstructure. Compressive strength and failure load did not significantly differ between groups. These findings persisted after excluding patients with hypogonadism. Bone microarchitecture was not deficient in patients with GHD. Both cortical and trabecular microarchitecture are altered in men with acromegaly. Our data indicate that GH excess is associated with distinct effects in cortical vs trabecular bone compartments. Our observations also affirm the limitations of aBMD testing in the evaluation of patients with acromegaly. © 2017 European Society of Endocrinology.

Comparison of Periodized and Non-Periodized Resistance Training on Maximal Strength: A Meta-Analysis.

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Williams, Tyler D; Tolusso, Danilo V; Fedewa, Michael V; Esco, Michael R

2017-10-01

Periodization is a logical method of organizing training into sequential phases and cyclical time periods in order to increase the potential for achieving specific performance goals while minimizing the potential for overtraining. Periodized resistance training plans are proposed to be superior to non-periodized training plans for enhancing maximal strength. The primary aim of this study was to examine the previous literature comparing periodized resistance training plans to non-periodized resistance training plans and determine a quantitative estimate of effect on maximal strength. All studies included in the meta-analysis met the following inclusion criteria: (1) peer-reviewed publication; (2) published in English; (3) comparison of a periodized resistance training group to a non-periodized resistance training group; (4) maximal strength measured by 1-repetition maximum (1RM) squat, bench press, or leg press. Data were extracted and independently coded by two authors. Random-effects models were used to aggregate a mean effect size (ES), 95% confidence intervals (CIs) and potential moderators. The cumulative results of 81 effects gathered from 18 studies published between 1988 and 2015 indicated that the magnitude of improvement in 1RM following periodized resistance training was greater than non-periodized resistance training (ES = 0.43, 95% CI 0.27-0.58; P training status (β = -0.59; P = 0.0305), study length (β = 0.03; P = 0.0067), and training frequency (β = 0.46; P = 0.0123) were associated with a change in 1RM. These results indicate that undulating programs were more favorable for strength gains. Improvements in 1RM were greater among untrained participants. Additionally, higher training frequency and longer study length were associated with larger improvements in 1RM. These results suggest that periodized resistance training plans have a moderate effect on 1RM compared to non-periodized training plans. Variation in training stimuli

Effects of recycling and bonding agent application on bond strength of stainless steel orthodontic brackets.

Science.gov (United States)

Bahnasi, Faisal I; Abd-Rahman, Aida Na; Abu-Hassan, Mohame I

2013-10-01

1) to assess different methods of recycling orthodontic brackets, 2) to evaluate Shear Bond Strength (SBS) of (a) new, (b) recycled and (c) repeated recycled stainless steel brackets (i) with and (ii) without bracket base primer. A total of 180 extracted human premolar teeth and 180 premolar stainless steel brackets were used. One hundred teeth and 100 brackets were divided into five groups of 20-teeth each. Four methods of recycling orthodontic brackets were used in each of the first four groups while the last one (group V) was used as the control. Groups (I-V) were subjected to shear force within half an hour until the brackets debond. SBS was measured and the method showing the highest SBS was selected. A New group (VI) was recycled twice with the selected method. Six subgroups (1-6) were established; the primer was applied for three sub-groups, and the composite was applied for all brackets. Brackets were subjected to the same shear force, and SBS was measured for all sub-groups. There was a significant difference between the mean SBS of the sandblasting method and the means of SBS of each of the other three methods. There was however, no significant difference between the mean SBS of the new bracket and the mean SBS of recycled bracket using sandblasting. The mean SBS of all sub-groups were more than that recommended by Reynolds (17) in 1975. Brackets with primer showed slightly higher SBS compared to those of brackets without bonding agent. To decrease cost, sandblasted recycled orthodontic brackets can be used as an alternative to new brackets. It is recommended to apply a bonding agent on the bracket base to provide greater bond strength. Key words:Recycled bracket, shear bond strength, sandblasting, stainless steel orthodontic bracket.

Effects of recycling and bonding agent application on bond strength of stainless steel orthodontic brackets

Science.gov (United States)

Bahnasi, Faisal I.; Abu-Hassan, Mohame I.

2013-01-01

Objectives: 1) to assess different methods of recycling orthodontic brackets, 2) to evaluate Shear Bond Strength (SBS) of (a) new, (b) recycled and (c) repeated recycled stainless steel brackets (i) with and (ii) without bracket base primer. Study Design: A total of 180 extracted human premolar teeth and 180 premolar stainless steel brackets were used. One hundred teeth and 100 brackets were divided into five groups of 20-teeth each. Four methods of recycling orthodontic brackets were used in each of the first four groups while the last one (group V) was used as the control. Groups (I-V) were subjected to shear force within half an hour until the brackets debond. SBS was measured and the method showing the highest SBS was selected. A New group (VI) was recycled twice with the selected method. Six subgroups (1-6) were established; the primer was applied for three sub-groups, and the composite was applied for all brackets. Brackets were subjected to the same shear force, and SBS was measured for all sub-groups. Results: There was a significant difference between the mean SBS of the sandblasting method and the means of SBS of each of the other three methods. There was however, no significant difference between the mean SBS of the new bracket and the mean SBS of recycled bracket using sandblasting. The mean SBS of all sub-groups were more than that recommended by Reynolds (17) in 1975. Brackets with primer showed slightly higher SBS compared to those of brackets without bonding agent. Conclusion: To decrease cost, sandblasted recycled orthodontic brackets can be used as an alternative to new brackets. It is recommended to apply a bonding agent on the bracket base to provide greater bond strength. Key words:Recycled bracket, shear bond strength, sandblasting, stainless steel orthodontic bracket. PMID:24455081

Ultrahigh-strength submicron-sized metallic glass wires

International Nuclear Information System (INIS)

Wang, Y.B.; Lee, C.C.; Yi, J.; An, X.H.; Pan, M.X.; Xie, K.Y.; Liao, X.Z.; Cairney, J.M.; Ringer, S.P.; Wang, W.H.

2014-01-01

In situ deformation experiments were performed in a transmission electron microscope to investigate the mechanical properties of submicron-sized Pd 40 Cu 30 Ni 10 P 20 metallic glass (MG) wires. Results show that the submicron-sized MG wires exhibit intrinsic ultrahigh tensile strength of ∼2.8 GPa, which is nearly twice as high as that in their bulk counterpart, and ∼5% elastic strain approaching the elastic limits. The tensile strength, engineering strain at failure and deformation mode of the submicron-sized MG wires depend on the diameter of the wires

Relationship between tongue strength, lip strength, and nutrition-related sarcopenia in older rehabilitation inpatients: a cross-sectional study

Directory of Open Access Journals (Sweden)

Sakai K

2017-08-01

Full Text Available Kotomi Sakai,1,2 Enri Nakayama,2 Haruka Tohara,3 Keiji Kodama,4 Takahiro Takehisa,5 Yozo Takehisa,6 Koichiro Ueda2 1Department of Rehabilitation Medicine, Setagaya Memorial Hospital, 2Department of Dysphagia Rehabilitation, Nihon University School of Dentistry, 3Gerodontology and Oral Rehabilitation, Department of Gerontology and Gerodontology, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, 4Department of Internal Medicine, 5Department of Orthopaedic Surgery, Setagaya Memorial Hospital, Tokyo, 6Department of Internal Medicine, Hakuai Memorial Hospital, Tokushima, Japan Objective: The objective of this study was to clarify the relationship between tongue strength, lip strength, and nutrition-related sarcopenia (NRS.Patients and methods: A total of 201 older inpatients aged ≥65 years (70 men, median age: 84 years, interquartile range: 79–89 years consecutively admitted for rehabilitation were included in this cross-sectional study. The main factors evaluated were the presence of NRS diagnosed by malnutrition using the Mini-Nutrition Assessment – Short Form, sarcopenia based on the criteria of the Asian Working Group for Sarcopenia, tongue strength, and lip strength. Other factors such as age, sex, comorbidity, physical function, cognitive function, and oral intake level were also assessed.Results: In all, 78 (38.8% patients were allocated to the NRS group, and 123 (61.2% patients were allocated to the non-NRS group. The median tongue strength and lip strength (interquartile range were significantly lower in the NRS group (tongue: 22.9 kPa [17.7–27.7 kPa] and lip: 7.2 N [5.6–9.8 N] compared with the non-NRS group (tongue: 29.7 kPa [24.8–35.1 kPa] and lip: 9.9 N [8.4–12.3 N], P<0.001 for both. Multivariable logistic regression analysis showed that NRS was independently associated with tongue strength (odds ratio [OR] =0.93, 95% confidence interval [CI] 0.87–0.98, P=0.012 and lip

Profile of isokinetic eccentric-to-concentric strength ratios of shoulder rotator muscles in elite female team handball players.

Science.gov (United States)

Andrade, Marilia Dos Santos; Fleury, Anna Maria; de Lira, Claudio Andre Barbosia; Dubas, Joao Paulo; da Silva, Antonio Carlos

2010-05-01

The purpose of this study was to establish the isokinetic profile of shoulder rotator muscles strength in female handball players. Twenty-seven handball players performed concentric and eccentric strength tests of both dominant and non-dominant upper limbs on an isokinetic dynamometer. Internal and external rotator muscles peak torque was assessed at 1.05, 3.14, and 5.23 rad . s(-1) in concentric mode and at 3.14 and 5.23 rad . s(-1) in eccentric mode. Concentric balance ratio and functional ratio were obtained. Bi-lateral deficiency was compared. Concentric strength for internal and external rotation was significantly greater for the dominant than for the non-dominant limb for all speeds (P muscles were stronger in the dominant than the non-dominant limb (P stronger than the non-dominant side, balance concentric ratios remained the same, with only the functional strength ratio different at 5.23 rad . s(-1). Our results suggest that concentric strength exercises be used for internal and external rotators on the non-dominant side, and functional exercise that improves eccentric rotation strength for prevention programmes.

In vitro tensile strength of luting cements on metallic substrate.

Science.gov (United States)

Orsi, Iara A; Varoli, Fernando K; Pieroni, Carlos H P; Ferreira, Marly C C G; Borie, Eduardo

2014-01-01

The aim of this study was to determine the tensile strength of crowns cemented on metallic substrate with four different types of luting agents. Twenty human maxillary molars with similar diameters were selected and prepared to receive metallic core castings (Cu-Al). After cementation and preparation the cores were measured and the area of crown's portion was calculated. The teeth were divided into four groups based on the luting agent used to cement the crowns: zinc phosphate cement; glass ionomer cement; resin cement Rely X; and resin cement Panavia F. The teeth with the crowns cemented were subjected to thermocycling and later to the tensile strength test using universal testing machine with a load cell of 200 kgf and a crosshead speed of 0.5 mm/min. The load required to dislodge the crowns was recorded and converted to MPa/mm(2). Data were subjected to Kruskal-Wallis analysis with a significance level of 1%. Panavia F showed significantly higher retention in core casts (3.067 MPa/mm(2)), when compared with the other cements. Rely X showed a mean retention value of 1.877 MPa/mm(2) and the zinc phosphate cement with 1.155 MPa/mm(2). Glass ionomer cement (0.884 MPa/mm(2)) exhibited the lowest tensile strength value. Crowns cemented with Panavia F on cast metallic posts and cores presented higher tensile strength. The glass ionomer cement showed the lowest tensile strength among all the cements studied.

[Autoerotic fatalities in Greater Dusseldorf].

Science.gov (United States)

Hartung, Benno; Hellen, Florence; Borchard, Nora; Huckenbeck, Wolfgang

2011-01-01

Autoerotic fatalities in the Greater Dusseldorf area correspond to the relevant medicolegal literature. Our results included exclusively young to middle-aged, usually single men who were found dead in their city apartments. Clothing and devices used showed a great variety. Women's or fetish clothing and complex shackling or hanging devices were disproportionately frequent. In most cases, death occurred due to hanging or ligature strangulation. There was no increased incidence of underlying psychiatric disorders. In most of the deceased no or at least no remarkable alcohol intoxication was found. Occasionally, it may be difficult to reliably differentiate autoerotic accidents, accidents occurring in connection with practices of bondage & discipline, dominance & submission (BDSM) from natural death, suicide or homicide.

Normal isometric strength of rotatorcuff muscles in adults.

Science.gov (United States)

Chezar, A; Berkovitch, Y; Haddad, M; Keren, Y; Soudry, M; Rosenberg, N

2013-01-01

The most prevalent disorders of the shoulder are related to the muscles of rotator cuff. In order to develop a mechanical method for the evaluation of the rotator cuff muscles, we created a database of isometric force generation by the rotator cuff muscles in normal adult population. We hypothesised the existence of variations according to age, gender and dominancy of limb. A total of 400 healthy adult volunteers were tested, classified into groups of 50 men and women for each decade of life. Maximal isometric force was measured at standardised positions for supraspinatus, infraspinatus and subscapularis muscles in both shoulders in every person. Torque of the force was calculated and normalised to lean body mass. The profiles of mean torque-time curves for each age and gender group were compared. Our data showed that men gradually gained maximal strength in the fifth decade, and showed decreased strength in the sixth. In women the maximal strength was gained in the fourth decade with gradual decline to the sixth decade of life. The dominant arm was stronger in most of the tested groups. The torque profiles of the rotator cuff muscles in men at all ages were significantly higher than that in women. We found previously unrecognised variations of rotator cuff muscles' isometric strength according to age, gender and dominancy in a normal population. The presented data may serve as a basis for the future studies for identification of the abnormal patterns of muscle isometric strength in patients with pathology of the rotator cuff muscles. Cite this article: Bone Joint Res 2013;2:214-19.

Shoulder rotator isokinetic strength profile in young swimmers

Directory of Open Access Journals (Sweden)

Nuno Miguel Prazeres Batalha

2012-08-01

Full Text Available DOI: http://dx.doi.org/10.5007/1980-0037.2012v14n5p545  Considering that some studies suggest that shoulder rotators muscle imbal­ances are related to joint pain and injury, and that there are no normative data for young swimmers, the aim of this study was: i to describe the muscle balance, fatigue and isokinetic strength profile of the shoulder rotators in young swimmers; ii to compare the results between swimmers and a group of young non-practitioners; iii to contribute to the acquisition of normative data of unilateral ratios of shoulder rotators. We evaluated the shoulder rotators concentric strength and unilateral ratios (ratio between torque of external and internal rotators of 60 swimmers (age: 14.55 ± 0.5 years old; body mass: 61.16 ± 7.08 kg and 60 non-practitioners (age: 14.62 ± 0.49 years old; body mass: 60.22 ± 10.01 kg. The evaluation was performed in the sitting position (90° abduction and elbow flexion at 60º.s-1 and 180º.s-1 angular speeds using an isokinetic dynamometer (Biodex System 3. The results of the fatigue ratios revealed no differences between the groups. Swimmers showed unilateral ratios of 73.39 ± 17.26% in the dominant limb (DL and 77.89 ± 15,23% in the non-dominant limb (NDL for assessments at 60º.s-1. At 180º.s-1, ratios were 74.77± 13.99% for DL and 70.11 ± 14.57% for NDL. Swimmers presented greater muscle imbalance, and differed from non-practitioners in the ability to produce power with the internal rotators, which was significantly higher in the former group.

Importance of regional variation in conservation planning: A rangewide example of the Greater Sage-Grouse

Science.gov (United States)

Doherty, Kevin E.; Evans, Jeffrey S.; Coates, Peter S.; Juliusson, Lara; Fedy, Bradley C.

2016-01-01

We developed rangewide population and habitat models for Greater Sage-Grouse (Centrocercus urophasianus) that account for regional variation in habitat selection and relative densities of birds for use in conservation planning and risk assessments. We developed a probabilistic model of occupied breeding habitat by statistically linking habitat characteristics within 4 miles of an occupied lek using a nonlinear machine learning technique (Random Forests). Habitat characteristics used were quantified in GIS and represent standard abiotic and biotic variables related to sage-grouse biology. Statistical model fit was high (mean correctly classified = 82.0%, range = 75.4–88.0%) as were cross-validation statistics (mean = 80.9%, range = 75.1–85.8%). We also developed a spatially explicit model to quantify the relative density of breeding birds across each Greater Sage-Grouse management zone. The models demonstrate distinct clustering of relative abundance of sage-grouse populations across all management zones. On average, approximately half of the breeding population is predicted to be within 10% of the occupied range. We also found that 80% of sage-grouse populations were contained in 25–34% of the occupied range within each management zone. Our rangewide population and habitat models account for regional variation in habitat selection and the relative densities of birds, and thus, they can serve as a consistent and common currency to assess how sage-grouse habitat and populations overlap with conservation actions or threats over the entire sage-grouse range. We also quantified differences in functional habitat responses and disturbance thresholds across the Western Association of Fish and Wildlife Agencies (WAFWA) management zones using statistical relationships identified during habitat modeling. Even for a species as specialized as Greater Sage-Grouse, our results show that ecological context matters in both the strength of habitat selection (i

Long-term outcome of muscle strength in ulnar and median nerve injury: Comparing manual muscle strength testing, grip and pinch strength dynamometers and a new intrinsic muscle strength dynamometer

NARCIS (Netherlands)

A.R. Schreuders (Ton); M.E. Roebroeck (Marij); J.B. Jaquet (Jean); S.E.R. Hovius (Steven); H.J. Stam (Henk)

2004-01-01

textabstractObjective: To compare the outcome of muscle strength with manual muscle strength testing grip and pinch strength measurements and a dynamometer which allows for measurements of the intrinsic muscles of the hand in isolation (the Rotterdam Intrinsic Hand Myometer, RIHM). Methods:

Effect of strength training with blood flow restriction on muscle power and submaximal strength in eumenorrheic women.

Science.gov (United States)

Gil, Ana L S; Neto, Gabriel R; Sousa, Maria S C; Dias, Ingrid; Vianna, Jeferson; Nunes, Rodolfo A M; Novaes, Jefferson S

2017-03-01

Blood flow restriction (BFR) training stimulates muscle size and strength by increasing muscle activation, accumulation of metabolites and muscle swelling. This method has been used in different populations, but no studies have evaluated the effects of training on muscle power and submaximal strength (SS) in accounted for the menstrual cycle. The aim of this study was to analyse the effect of strength training (ST) with BFR on the muscle power and SS of upper and lower limbs in eumenorrheic women. Forty untrained women (18-40 years) were divided randomly and proportionally into four groups: (i) high-intensity ST at 80% of 1RM (HI), (ii) low-intensity ST at 20% of 1RM combined with partial blood flow restriction (LI + BFR), (iii) low-intensity ST at 20% of 1RM (LI) and d) control group (CG). Each training group performed eight training sessions. Tests with a medicine ball (MB), horizontal jump (HJ), vertical jump (VJ), biceps curls (BC) and knee extension (KE) were performed during the 1st day follicular phase (FP), 14th day (ovulatory phase) and 26-28th days (luteal phase) of the menstrual cycle. There was no significant difference among groups in terms of the MB, HJ, VJ or BC results at any time point (P>0·05). SS in the KE exercise was significantly greater in the LI + BFR group compared to the CG group (P = 0·014) during the LP. Therefore, ST with BFR does not appear to improve the power of upper and lower limbs and may be an alternative to improve the SS of lower limbs of eumenorrheic women. © 2015 Scandinavian Society of Clinical Physiology and Nuclear Medicine. Published by John Wiley & Sons Ltd.

Gender differences in commuting behavior: Women's greater sensitivity

Energy Technology Data Exchange (ETDEWEB)

Olmo Sanchez, M.I.; Maeso Gonzalez, E.

2016-07-01

Women's greater sensitivity to changes in their environment is one of the most distinguishing features between both genders. This article raises women's greater sensitivity to the different variables which influence their commuting modal choice. In order to do this, gender gaps detected in the choice of means of transport in commuting trips with respect to the decision factors such as age, education level, driver's license, private transport access; location, household size and net income, are quantified.The results show a greater female sensitivity to the different variables that affect their modal choice, which helps to better understand the different mobility patterns and it is useful for planning measures favoring sustainable mobility policies and equity. (Author)

Increasing the Strength of Adhesively Bonded Joints by Tapering the Adherends

International Nuclear Information System (INIS)

GUESS, TOMMY R.; METZINGER, KURT E.

1999-01-01

Wind turbine blades are often fabricated with composite materials. These composite blades are frequently attached to a metallic structure with an adhesive bond. For the baseline composite-to-steel joint considered in this study, failure typically occurs when the adhesive debonds from the steel adherend. Previous efforts established that the adhesive peel stresses strongly influence the strength of these joints for both single-cycle and fatigue loading. This study focused on reducing the adhesive peel stresses present in these joints by tapering the steel adherends. Several different tapers were evaluated using finite element analysis before arriving at a final design. To confirm that the selected taper was an improvement to the existing design, the baseline joint and the modified joint were tested in both compression and tension. In these axial tests, the compressive strengths of the joints with tapered adherends were greater than those of the baseline joints for both single-cycle and low-cycle fatigue. In addition, only a minor reduction in tensile strength was observed for the joints with tapered adherends when compared to the baseline joints. Thus, the modification would be expected to enhance the overall performance of this joint

A finite element study on the effects of toughness and permanent out-of-plane deformation on post-impact compressive strength

OpenAIRE

Bull, Daniel; Spearing, Simon; Sinclair, Ian

2015-01-01

This study applies mechanisms observed from previous work (the undamaged cone, toughness and extent of permanent out-of-plane deformation) to parametrically study their effects on residual compression after impact (CAI) strength using finite element models. Based on previous experimental work, tougher material systems exhibited up to 30% greater CAI strength for a given damage area. Based on this, it is necessary to understand what other parameters, beyond damage area, contribute to a loss in...

High-Strength Low-Alloy Steel Strengthened by Multiply Nanoscale Microstructures

Science.gov (United States)

Shen, Y. F.; Zuo, L.

Recently, we have being focused on improving the strength without sacrificing ductility of High-strength low-alloy (HSLA) steels by designing nanostructures. Several developments have been obtained, summarized as the following three parts: (a) Depressively nanoscale precipitates: A ferritic steel with finely dispersed precipitates reveals a yield strength of 760 MPa, approximately three times higher than that of conventional Ti-bearing high strength hot-rolled sheet steels, and its ultimate tensile strength reaches 850 MPa with an elongation-to-failure value of 18%. The finely dispersed TiC precipitates in the matrix provide matrix strengthening. The estimated magnitude of precipitation strengthening is around 458 MPa. The effects of the particle size, particle distribution and intrinsic particle strength have been investigated through dislocation dynamics (DD) simulations. The DD results show that strengthening is not only a function of the density of the nano-scale precipitates but also of their size. (b) Ultrafinely ferritic plate: An interstitial-free (IF) steel sheet with a cold-rolling reduction of 75% shows a high tensile strength (710MPa) while preserving a considerable plastic strain (13%). The ductility recovery with increasing the rolling reduction up to 75% is related with the decreasing both in lamellar spacings and cell blocks sizes. (c) Parallel nano-laminated austenite: A composite microstructure consisting of ferrite, bainitic ferrite (BF) laths and retained austenite (RA) platelets has been found for the steel with a chemical composition of 0.19C-0.30Si-1.76Mn-1.52Al (in mass fraction), processed with annealing and bainitic holding. The sample annealed at 820oC (for 120s) and partitioned at 400oC (for 300s) has the best combination of ultimate tensile strength (UTS, 682 MPa) and elongation to failure ( 70%) with about 26% of BF plates 16% RA in its microstructure.

The Effects of Eccentric Contraction Duration on Muscle Strength, Power Production, Vertical Jump, and Soreness.

Science.gov (United States)

Mike, Jonathan N; Cole, Nathan; Herrera, Chris; VanDusseldorp, Trisha; Kravitz, Len; Kerksick, Chad M

2017-03-01

significance but there was a trend toward a difference (G × T, p = 0.07). No other significant (p > 0.05) G × T interaction effects were found for the performance variables. All groups showed significant main effects for time in 1RM (p jump (p = 0.004), peak power (p jump protocol as a result of the 4-week training program (p = 0.03). Soreness data revealed significant increases across time in all groups at both week 0 and week 4. Paired sample t-tests revealed greater differences in soreness values across time in the 2S group. The results provide further evidence that resistance training with eccentrically dominated movement patterns can be an effective method to acutely increase maximal strength and power expression in trained college age men. Furthermore, longer eccentric contractions may negatively impact explosive movements such as the vertical jump, whereas shorter eccentric contractions may instigate greater amounts of soreness. These are important considerations for the strength and conditioning professional to more fully understand that expressions of strength and power through eccentric training and varying durations of eccentric activity can have a significant impact for populations ranging from athletes desiring peak performance.

Distribution of radiative strength with excitation energy: the E1 and M1 giant resonances

International Nuclear Information System (INIS)

Brown, G.E.; Speth, J.

1979-01-01

Calculations of the giant dipole resonance in the particle-hole model, employing empirical values for the unperturbed particle and hole energies, have been unsuccessful in pushing the dipole state to a sufficiently high energy. it is argued that unperturbed levels correspondign to an effective mass of m*/m approx. 0.6 to 0.7 should be employed. The couplings of particles and holes to vibrations are the crucial ingredients in these considerations. More generally, it is argued that the effective mass relevant to excitations near the Fermi surface is that corresponding to empirical single-particle levels, m*/m greater than or equal to 1.0. For particle-hole excitations above the Fermi surface, it is a decreasing function of excitation energy, reaching the above values 0.6 to 0.7 for E greater than or equal to 2 dirac constant/b omega, dirac constant/sub omega/ being the shell spacing. This has the consequence of spreading out the M1 strength. A new interpretation of experimental strengths is proposed

Laser solder welding of articular cartilage: tensile strength and chondrocyte viability.

Science.gov (United States)

Züger, B J; Ott, B; Mainil-Varlet, P; Schaffner, T; Clémence, J F; Weber, H P; Frenz, M

2001-01-01

The surgical treatment of full-thickness cartilage defects in the knee joint remains a therapeutic challenge. Recently, new techniques for articular cartilage transplantation, such as mosaicplasty, have become available for cartilage repair. The long-term success of these techniques, however, depends not only on the chondrocyte viability but also on a lateral integration of the implant. The goal of this study was to evaluate the feasibility of cartilage welding by using albumin solder that was dye-enhanced to allow coagulation with 808-nm laser diode irradiation. Conventional histology of light microscopy was compared with a viability staining to precisely determine the extent of thermal damage after laser welding. Indocyanine green (ICG) enhanced albumin solder (25% albumin, 0.5% HA, 0.1% ICG) was used for articular cartilage welding. For coagulation, the solder was irradiated through the cartilage implant by 808-nm laser light and the tensile strength of the weld was measured. Viability staining revealed a thermal damage of typically 500 m in depth at an irradiance of approximately 10 W/cm(2) for 8 seconds, whereas conventional histologies showed only half of the extent found by the viability test. Heat-bath investigations revealed a threshold temperature of minimum 54 degrees C for thermal damage of chondrocytes. Efficient cartilage bonding was obtained by using bovine albumin solder as adhesive. Maximum tensile strength of more than 10 N/cm(2) was achieved. Viability tests revealed that the thermal damage is much greater (up to twice) than expected after light microscopic characterization. This study shows the feasibility to strongly laser weld cartilage on cartilage by use of a dye-enhanced albumin solder. Possibilities to reduce the range of damage are suggested. Copyright 2001 Wiley-Liss, Inc.

Carrageenan as a dry strength additive for papermaking.

Directory of Open Access Journals (Sweden)

Zhenhua Liu

Full Text Available Carrageenans are commercially important sulfated gums found in various species of red seaweeds (Rhodophyta, wherein they serve a structural function similar to that of pectins in land plants. In this study, carrageenan was used independently or in combination with cationic polyacrylamide (CPAM and/or Al2(SO43 to explore its application as a dry strength additive in papermaking. Strength index determination, ash content detection, FTIR characterization and SEM observation were performed on prepared handsheets. The results showed that with 0.6% Al2(SO43 and 0.2% carrageenan as additives, the tensile index increased by 13.53% and precipitated calcium carbonate (PCC retention increased by 57.06%. With 0.6% Al2(SO43, 0.2% carrageenan and 0.03% CPAM as additives, PCC retention increased by 121% while the tensile index did not fall compared to handsheets without additives, indicating that carrageenan could enhance the strength of handsheets and be used as an anionic dry strength agent.

Effect of Compaction on Compressive Strength of Unfired Clay Blocks

International Nuclear Information System (INIS)

Lakho, N.A.; Zardari, M.A.; Pathan, A.A.

2016-01-01

This study investigates the possible use of unfired compacted clay blocks as a substitute of CSEB (Compressed Stabilized Earth Blocks) for the construction of economical houses. Cubes of 150 mm size were cut from the clay blocks which were compacted at various intensities of pressure during the casting. The results show that the compressive strength of the clay cubes increased with the compacting pressure to which the blocks were subjected during casting. The average crushing strength of the cubes, sawed from clay blocks that were subjected to compacting pressure of 7.2 MPa, was found to be 4.4 MPa. This value of compressive strength is about 50 percent more than that of normal CSEB. This study shows that the compacted clay blocks could be used as economical walling material as replacement of CSEB. (author)

Inpatient rehabilitation improves functional capacity, peripheral muscle strength and quality of life in patients with community-acquired pneumonia: a randomised trial

Directory of Open Access Journals (Sweden)

Anderson José

2016-04-01

Full Text Available Question: Among people who are hospitalised for community-acquired pneumonia, does an inpatient exercise-based rehabilitation program improve functional outcomes, symptoms, quality of life and length of hospital stay more than a respiratory physiotherapy regimen? Design: Randomised trial with concealed allocation, intention-to-treat analysis and blinding of some outcomes. Participants: Forty-nine adults hospitalised for community-acquired pneumonia. Intervention: The experimental group (n = 32 underwent a physical training program that included warm-up, stretching, peripheral muscle strength training and walking at a controlled speed for 15 minutes. The control group (n = 17 underwent a respiratory physiotherapy regimen that included percussion, vibrocompression, respiratory exercises and free walking. The intervention regimens lasted 8 days. Outcome measures: The primary outcome was the Glittre Activities of Daily Living test, which assesses the time taken to complete a series of functional tasks (eg, rising from a chair, walking, stairs, lifting and bending. Secondary outcomes were distance walked in the incremental shuttle walk test, peripheral muscle strength, quality of life, dyspnoea, lung function, C-reactive protein and length of hospital stay. Measures were taken 1 day before and 1 day after the intervention period. Results: There was greater improvement in the experimental group than in the control group on the Glittre Activities of Daily Living test (mean between-group difference 39 seconds, 95% CI 20 to 59 and the incremental shuttle walk test (mean between-group difference 130 m, 95% CI 77 to 182. There were also significantly greater improvements in quality of life, dyspnoea and peripheral muscle strength in the experimental group than in the control group. There were no between-group differences in lung function, C-reactive protein or length of hospital stay. Conclusion: The improvement in functional outcomes after an

Cervical range of motion, cervical and shoulder strength in senior versus age-grade Rugby Union International front-row forwards.

Science.gov (United States)

Davies, Mark; Moore, Isabel S; Moran, Patrick; Mathema, Prabhat; Ranson, Craig A

2016-05-01

To provide normative values for cervical range of motion (CROM), isometric cervical and shoulder strength for; International Senior professional, and International Age-grade Rugby Union front-row forwards. Cross-sectional population study. All international level front-row players within a Rugby Union Tier 1 Nation. Nineteen Senior and 21 Age-grade front-row forwards underwent CROM, cervical and shoulder strength testing. CROM was measured using the CROM device and the Gatherer System was used to measure multi-directional isometric cervical and shoulder strength. The Age-grade players had significantly lower; cervical strength (26-57% deficits), cervical flexion to extension strength ratios (0.5 vs. 0.6), and shoulder strength (2-36% deficits) than the Senior players. However, there were no differences between front-row positions within each age group. Additionally, there were no differences between age groups or front-row positions in the CROM measurements. Senior Rugby Union front-row forwards have greater cervical and shoulder strength than Age-grade players, with the biggest differences being in cervical strength, highlighting the need for age specific normative values. Importantly, Age-grade players should be evaluated to ensure they have developed sufficient cervical strength prior to entering professional level Rugby Union. Copyright © 2015 Elsevier Ltd. All rights reserved.

Traditional versus functional strength training: Effects on muscle strength and power in the elderly

OpenAIRE

Seiler, Hilde Lohne; Torstveit, Monica Klungland; Anderssen, Sigmund A.

2013-01-01

Published versiom of an article in the journal:Journal of Aging and Physical Activity. Also available from Human Kinetics: http://http://journals.humankinetics.com/japa-back-issues/japa-volume-21-issue-1-january/traditional-versus-functional-strength-training-effects-on-muscle-strength-and-power-in-the-elderly The aim was to determine whether strength training with machines vs. functional strength training at 80% of one-repetition maximum improves muscle strength and power among the elderl...

Relative scale and the strength and deformability of rock masses

Science.gov (United States)

Schultz, Richard A.

1996-09-01

The strength and deformation of rocks depend strongly on the degree of fracturing, which can be assessed in the field and related systematically to these properties. Appropriate Mohr envelopes obtained from the Rock Mass Rating (RMR) classification system and the Hoek-Brown criterion for outcrops and other large-scale exposures of fractured rocks show that rock-mass cohesive strength, tensile strength, and unconfined compressive strength can be reduced by as much as a factor often relative to values for the unfractured material. The rock-mass deformation modulus is also reduced relative to Young's modulus. A "cook-book" example illustrates the use of RMR in field applications. The smaller values of rock-mass strength and deformability imply that there is a particular scale of observation whose identification is critical to applying laboratory measurements and associated failure criteria to geologic structures.

Empirical Strengths of Concrete Roof Slabs After 34 Years Service ...

African Journals Online (AJOL)

The results were compared with those from standard compressive strength machine in the laboratory, and subjected to statistical analysis. The final results showed that the lowest slab compressive strength was 14 N/mm2 below the minimum concrete grade of 25N/mm2; and percentage defective was 29.5% more than the ...

Effects of sexual dimorphism and landscape composition on the trophic behavior of Greater Prairie-Chicken.

Directory of Open Access Journals (Sweden)

Beatriz Blanco-Fontao

Full Text Available Partitioning of ecological niche is expected in lekking species that show marked sexual size dimorphism as a consequence of sex-specific ecological constraints. However, niche partitioning is uncertain in species with moderate sexual dimorphism. In addition, the ecological niche of a species may also be affected by landscape composition; particularly, agricultural fragmentation may greatly influence the trophic behavior of herbivores. We studied trophic niche variation in Greater Prairie-Chickens (Tympanuchus cupido, a grouse species that shows moderate sex-dimorphism. Greater Prairie-Chickens are native to tallgrass prairies of North America, although populations persist in less natural mosaics of cropland and native habitats. We used stable isotope analysis of carbon and nitrogen in blood, claws and feathers to assess seasonal differences in trophic niche breadth and individual specialization between male and female Greater Prairie-Chickens, and between birds living in continuous and fragmented landscapes. We found that females showed broader niches and higher individual specialization than males, especially in winter and autumn. However, differences between females and males were smaller in spring when birds converge at leks, suggesting that females and males may exhibit similar feeding behaviors during the lekking period. In addition, we found that birds living in native prairies showed greater annual trophic variability than conspecifics in agricultural mosaic landscapes. Native habitats may provide greater dietary diversity, resulting in greater diversity of feeding strategies.

Evaluation of bond strength between grooved titanium alloy implant abutments and provisional veneering materials after surface treatment of the abutments: An in vitro study

Directory of Open Access Journals (Sweden)

Gowtham Venkat

2017-01-01

Full Text Available Introduction: Titanium has become the material of choice with greater applications in dental implants. The success of the dental implant does not only depend on the integration of the implant to the bone but also on the function and longevity of the superstructure. The clinical condition that demands long-term interim prosthesis is challenging owing to the decreased bond between the abutment and the veneering material. Hence, various surface treatments are done on the abutments to increase the bond strength. Aim: This study aimed to evaluate the bond strength between the abutment and the provisional veneering materials by surface treatments such as acid etching, laser etching, and sand blasting of the abutment. Materials and Methods: Forty titanium alloy abutments of 3 mm diameter and 11 mm height were grouped into four groups with ten samples. Groups A, B, C, and D are untreated abutments, sand blasted with 110 μm aluminum particles, etched with 1% hydrofluoric acid and 30% nitric acid, and laser etched with Nd: YAG laser, respectively. Provisional crowns were fabricated with bis-acrylic resin and cemented with noneugenol temporary luting cement. The shear bond strength was measured in universal testing machine using modified Shell–Nielsen shear test after the cemented samples were stored in water at 25°C for 24 h. Load was applied at a constant cross head speed of 5 mm/min until a sudden decrease in resistance indicative of bond failure was observed. The corresponding force values were recorded, and statistical analysis was done using one-way ANOVA and Newman–Keuls post hoc test. Results: The laser-etched samples showed higher bond strength. Conclusion: Among the three surface treatments, laser etching showed the highest bond strength between titanium alloy implant abutment and provisional restorations. The sand-blasted surfaces demonstrated a significant difference in bond strength compared to laser-etched surfaces. The results of this

Evaluation of Bond Strength between Grooved Titanium Alloy Implant Abutments and Provisional Veneering Materials after Surface Treatment of the Abutments: An In vitro Study.

Science.gov (United States)

Venkat, Gowtham; Krishnan, Murugesan; Srinivasan, Suganya; Balasubramanian, Muthukumar

2017-01-01

Titanium has become the material of choice with greater applications in dental implants. The success of the dental implant does not only depend on the integration of the implant to the bone but also on the function and longevity of the superstructure. The clinical condition that demands long-term interim prosthesis is challenging owing to the decreased bond between the abutment and the veneering material. Hence, various surface treatments are done on the abutments to increase the bond strength. This study aimed to evaluate the bond strength between the abutment and the provisional veneering materials by surface treatments such as acid etching, laser etching, and sand blasting of the abutment. Forty titanium alloy abutments of 3 mm diameter and 11 mm height were grouped into four groups with ten samples. Groups A, B, C, and D are untreated abutments, sand blasted with 110 μm aluminum particles, etched with 1% hydrofluoric acid and 30% nitric acid, and laser etched with Nd: YAG laser, respectively. Provisional crowns were fabricated with bis-acrylic resin and cemented with noneugenol temporary luting cement. The shear bond strength was measured in universal testing machine using modified Shell-Nielsen shear test after the cemented samples were stored in water at 25°C for 24 h. Load was applied at a constant cross head speed of 5 mm/min until a sudden decrease in resistance indicative of bond failure was observed. The corresponding force values were recorded, and statistical analysis was done using one-way ANOVA and Newman-Keuls post hoc test. The laser-etched samples showed higher bond strength. Among the three surface treatments, laser etching showed the highest bond strength between titanium alloy implant abutment and provisional restorations. The sand-blasted surfaces demonstrated a significant difference in bond strength compared to laser-etched surfaces. The results of this study confirmed that a combination of surface treatments and bond agents enhances the

Gas, Oil, and Water Production from Jonah, Pinedale, Greater Wamsutter, and Stagecoach Draw Fields in the Greater Green River Basin, Wyoming

Science.gov (United States)

Nelson, Philip H.; Ewald, Shauna M.; Santus, Stephen L.; Trainor, Patrick K.

2010-01-01

Gas, oil, and water production data were compiled from selected wells in four gas fields in rocks of Late Cretaceous age in southwestern Wyoming. This study is one of a series of reports examining fluid production from tight-gas reservoirs, which are characterized by low permeability, low porosity, and the presence of clay minerals in pore space. Production from each well is represented by two samples spaced five years apart, the first sample typically taken two years after commencement of production. For each producing interval, summary diagrams of oil versus gas and water versus gas production show fluid production rates, the change in rates during five years, the water-gas and oil-gas ratios, and the fluid type. These diagrams permit well-to-well and field-to-field comparisons. Fields producing water at low rates (water dissolved in gas in the reservoir) can be distinguished from fields producing water at moderate or high rates, and the water-gas ratios are quantified. The ranges of first-sample gas rates in Pinedale field and Jonah field are quite similar, and the average gas production rate for the second sample, taken five years later, is about one-half that of the first sample for both fields. Water rates are generally substantially higher in Pinedale than in Jonah, and water-gas ratios in Pinedale are roughly a factor of ten greater in Pinedale than in Jonah. Gas and water production rates from each field are fairly well grouped, indicating that Pinedale and Jonah fields are fairly cohesive gas-water systems. Pinedale field appears to be remarkably uniform in its flow behavior with time. Jonah field, which is internally faulted, exhibits a small spread in first-sample production rates. In the Greater Wamsutter field, gas production from the upper part of the Almond Formation is greater than from the main part of the Almond. Some wells in the main and the combined (upper and main parts) Almond show increases in water production with time, whereas increases

Evaluation of methods for increasing vacuum breakdown strength

International Nuclear Information System (INIS)

Evans, R.D.; Cooke, C.M.; Berman, E.R.

1977-01-01

Research to determine the effectiveness of coated and gas shielded cathodes as a means of increasing vacuum breakdown strength under short pulse conditions is reported. A technique for rapidly evaluating large numbers of coatings on small electrodes at relatively low pulse voltage (120 kV or less) and methods for testing larger electrodes and fewer coatings at higher total voltage were developed. Experiments with gas shielded cathodes were also conducted. Results suggest that it may be possible to eliminate prebreakdown current and to double breakdown strength by applying a suitable coating to the cathode. Breakdown stresses in excess of 2 MV/cm were obtained in a 0.5 mm gap with sputtered coatings of alumina, Cr 2 O 3 , and several readily available epoxies. Electrodes two orders of magnitude greater in area were tested, and stresses approaching 1 MV/cm were measured in 5 mm gaps for several epoxies and for alumina. It has further been shown that, because similar trends occurred in the data from large and small experiments, it should be possible to screen potential coatings rapidly and effectively with minimum expenditure using a method similar to that employed for small electrodes at low pulse voltage

Ecological specialization and morphological diversification in Greater Antillean boas.

Science.gov (United States)

Reynolds, R Graham; Collar, David C; Pasachnik, Stesha A; Niemiller, Matthew L; Puente-Rolón, Alberto R; Revell, Liam J

2016-08-01

Colonization of islands can dramatically influence the evolutionary trajectories of organisms, with both deterministic and stochastic processes driving adaptation and diversification. Some island colonists evolve extremely large or small body sizes, presumably in response to unique ecological circumstances present on islands. One example of this phenomenon, the Greater Antillean boas, includes both small (<90 cm) and large (4 m) species occurring on the Greater Antilles and Bahamas, with some islands supporting pairs or trios of body-size divergent species. These boas have been shown to comprise a monophyletic radiation arising from a Miocene dispersal event to the Greater Antilles, though it is not known whether co-occurrence of small and large species is a result of dispersal or in situ evolution. Here, we provide the first comprehensive species phylogeny for this clade combined with morphometric and ecological data to show that small body size evolved repeatedly on separate islands in association with specialization in substrate use. Our results further suggest that microhabitat specialization is linked to increased rates of head shape diversification among specialists. Our findings show that ecological specialization following island colonization promotes morphological diversity through deterministic body size evolution and cranial morphological diversification that is contingent on island- and species-specific factors. © 2016 The Author(s). Evolution © 2016 The Society for the Study of Evolution.

Thermal degradation and tensile strength of sansevieria trifasciata-polypropylene composites

Science.gov (United States)

Abral, H.; Kenedy, E.

2015-07-01

The paper exhibits thermal degradation and tensile strength of Sansevieria Trifasciata (ST) fibers and polypropylene (PP) composites. Thermal degradation of ST fibers PP composites was conducted by using thermogravimetry (TGA) instrument, meanwhile tensile strength of the composite was done by using tensile equipment. The results show that the thermal resistance of ST fibers PP composites was higher than that of virgin PP only. Increases in volume fraction of fibers in the composites enhance the tensile strength. Scanning Electron Microscope (SEM) observation exhibits good interface bonding between ST fibers and PP matrix.

Thermal degradation and tensile strength of sansevieria trifasciata-polypropylene composites

International Nuclear Information System (INIS)

Abral, H; Kenedy, E

2015-01-01

The paper exhibits thermal degradation and tensile strength of Sansevieria Trifasciata (ST) fibers and polypropylene (PP) composites. Thermal degradation of ST fibers PP composites was conducted by using thermogravimetry (TGA) instrument, meanwhile tensile strength of the composite was done by using tensile equipment. The results show that the thermal resistance of ST fibers PP composites was higher than that of virgin PP only. Increases in volume fraction of fibers in the composites enhance the tensile strength. Scanning Electron Microscope (SEM) observation exhibits good interface bonding between ST fibers and PP matrix. (paper)

The impact of obesity on skeletal muscle strength and structure through adolescence to old age.

Science.gov (United States)

Tomlinson, D J; Erskine, R M; Morse, C I; Winwood, K; Onambélé-Pearson, Gladys

2016-06-01

Obesity is associated with functional limitations in muscle performance and increased likelihood of developing a functional disability such as mobility, strength, postural and dynamic balance limitations. The consensus is that obese individuals, regardless of age, have a greater absolute maximum muscle strength compared to non-obese persons, suggesting that increased adiposity acts as a chronic overload stimulus on the antigravity muscles (e.g., quadriceps and calf), thus increasing muscle size and strength. However, when maximum muscular strength is normalised to body mass, obese individuals appear weaker. This relative weakness may be caused by reduced mobility, neural adaptations and changes in muscle morphology. Discrepancies in the literature remain for maximal strength normalised to muscle mass (muscle quality) and can potentially be explained through accounting for the measurement protocol contributing to muscle strength capacity that need to be explored in more depth such as antagonist muscle co-activation, muscle architecture, a criterion valid measurement of muscle size and an accurate measurement of physical activity levels. Current evidence demonstrating the effect of obesity on muscle quality is limited. These factors not being recorded in some of the existing literature suggest a potential underestimation of muscle force either in terms of absolute force production or relative to muscle mass; thus the true effect of obesity upon skeletal muscle size, structure and function, including any interactions with ageing effects, remains to be elucidated.

Strength of vacuum brazed joints for repair; Haallfasthet hos reparationer utfoerda med vakuumloedning

Energy Technology Data Exchange (ETDEWEB)

Berglin, Leif [Siemens Industrial Turbomachinery AB, Finspaang (Sweden)

2005-04-01

Strength data are missing for braze joints. Repaired components cannot fully make use of the strength of the braze, and lifetime will be underestimated. The goal of the project was to generate material data to be able to prolong the lifetime of the components. Two different material combinations were tested, 12% Chromium steel brazed with BNi-2, and a nickel base alloy, IN792 brazed with BNi-5. Tensile testing at room temperature and elevated temperature was performed in the project. Target group is purchasers and suppliers of repaired components. A tensile test specimen with butt joint was developed in the project. The used test specimen worked well for the 12% Chromium steel. The results from testing show that proof stress and tensile strength are strongly depending on the joint gap, particularly at room temperature. High strength, close to base material strength, was achieved with joint gaps smaller than 50{mu}m. For wider joint gaps, strength was lower. Strength was approximately 25% of base material strength for joint gaps over 100{mu}m. The results can be explained by changes in microstructure. Joint gaps wider than 50{mu}m showed evidence of two-phase structure. At 500 deg C, the results also showed a connection between joint gap, microstructure and strength. The generated strength data can be used for calculations of lifetime for repaired components. Two different process errors were discovered in the manufacturing process of the brazed IN792 test specimens. The generated material data are therefor erroneous. The reason for this was two manufacturing errors. The tack welding was done with too high heat input. The surfaces of the joint gap became oxidised and the oxide hindered wetting of the braze. The second reason was that the brazing was done without the prescribed hold time at maximum temperature. The melting of the braze was therefor not completed when cooling started. As a result, the strength of the IN792 specimens was low at both temperatures.

Hydrothermal frictional strengths of rock and mineral samples relevant to the creeping section of the San Andreas Fault

Science.gov (United States)

Moore, Diane E.; Lockner, David A.; Hickman, Stephen H.

2016-01-01

We compare frictional strengths in the temperature range 25–250 °C of fault gouge from SAFOD (CDZ and SDZ) with quartzofeldspathic wall rocks typical of the central creeping section of the San Andreas Fault (Great Valley sequence and Franciscan Complex). The Great Valley and Franciscan samples have coefficients of friction, μ > 0.35 at all experimental conditions. Strength is unchanged between 25° and 150 °C, but μ increases at higher temperatures, exceeding 0.50 at 250 °C. Both samples are velocity strengthening at room temperature but show velocity-weakening behavior beginning at 150 °C and stick-slip motion at 250 °C. These rocks, therefore, have the potential for unstable seismic slip at depth. The CDZ gouge, with a high saponite content, is weak (μ = 0.09–0.17) and velocity strengthening in all experiments, and μ decreases at temperatures above 150 °C. Behavior of the SDZ is intermediate between the CDZ and wall rocks: μ < 0.2 and does not vary with temperature. Although saponite is probably not stable at depths greater than ∼3 km, substitution of the frictionally similar minerals talc and Mg-rich chlorite for saponite at higher temperatures could potentially extend the range of low strength and stable slip down to the base of the seismogenic zone.

Core strength and lower extremity alignment during single leg squats.

Science.gov (United States)

Willson, John D; Ireland, Mary Lloyd; Davis, Irene

2006-05-01

Muscles of the trunk, hip, and knee influence the orientation of the lower extremity during weight bearing activities. The purpose of this study was threefold: first, to compare the orientation of the lower extremity during a single leg (SL) squat among male and female athletes; second, to compare the strength of muscle groups in the trunk, hips, and knees between these individuals; and third, to evaluate the association between trunk, hip, and knee strength and the orientation of the knee joint during this activity. Twenty-four male and 22 female athletes participated in this study. Peak isometric torque was determined for the following muscle actions: trunk flexion, extension, and lateral flexion, hip abduction and external rotation, and knee flexion and extension. The frontal plane projection angle (FPPA) of the knee during a 45 degrees SL squat was determined using photo editing software. Males and females moved in opposite directions during the SL squat test (F(1,42) = 5.05, P = 0.03). Females typically moved toward more extreme FPPA during SL squats (P = 0.056), while males tended to move toward more neutral alignment (P = 0.066). Females also generated less torque in all muscle groups, with the exception of trunk extension. The projection angle of the knee during the SL squat test was most closely associated with hip external rotation strength. Using instruments suitable for a clinical setting, females were found to have greater FPPA and generally decreased trunk, hip, and knee isometric torque. Hip external rotation strength was most closely associated with the frontal plane projection angle.

Improvements in tongue strength and pressure-generation precision following a tongue-pressure training protocol in older individuals with dysphagia: Three case reports

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Erin M Yeates

2008-12-01

Full Text Available Erin M Yeates1, Sonja M Molfenter1, Catriona M Steele1,2,3,41Toronto Rehabilitation Institute, Toronto, Canada; 2Department of Speech-Language Pathology, University of Toronto, Toronto, Canada; 3Canadian Institutes of Health Research New Investigator in Aging; 4Bloorview Kids Rehab, Toronto, CanadaAbstract: Dysphagia, or difficulty swallowing, often occurs secondary to conditions such as stroke, head injury or progressive disease, many of which increase in frequency with advancing age. Sarcopenia, the gradual loss of muscle bulk and strength, can place older individuals at greater risk for dysphagia. Data are reported for three older participants in a pilot trial of a tongue-pressure training therapy. During the experimental therapy protocol, participants performed isometric strength exercises for the tongue as well as tongue pressure accuracy tasks. Biofeedback was provided using the Iowa Oral Performance Instrument (IOPI, an instrument that measures tongue pressure. Treatment outcome measures show increased isometric tongue strength, improved tongue pressure generation accuracy, improved bolus control on videofluoroscopy, and improved functional dietary intake by mouth. These preliminary results indicate that, for these three adults with dysphagia, tongue-pressure training was beneficial for improving both instrumental and functional aspects of swallowing. The experimental treatment protocol holds promise as a rehabilitative tool for various dysphagia populations.Keywords: speech-language pathology, dysphagia, rehabilitation, aging, strength, accuracy

Microstructure and bonding strength of Ni-based alloy coating

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LIU Qing

2006-05-01

Full Text Available A Ni-Cr-B-Si coating technique was developed and successfully applied on austenite grey iron substrate in a conventional resistance furnace under graphite powder protection. The microstructure, phase distribution, chemical composition profile and microhardness along the coating layer depth were investigated. Shear strength of the coating was also tested. Microanalysis shows that the coating is consist of γ-Ni solution and γ-Ni+Ni3B lamellar eutectic, as well as small amount of Cr5B3 particles. Diffusion induced metallurgical bonding occurs at the coating/substrate interfaces, and the higher the temperature, the more sufficient elements diffused, the broader interfusion region and the larger bonding strength, but it has an optimum value. And the bonding strength at the interface can be enable to reach 250-270 MPa, which is nearly the same as that of processed by flame spray. The microhardness along the coating layer depth shows a gradient distribution manner.

Calculating Outsourcing Strategies and Trials of Strength

DEFF Research Database (Denmark)

Christensen, Mark; Skærbæk, Peter; Tryggestad, Kjell

. The alternative option was an immediate outsourcing strategy with facility services being the object of large cross-functional contracts for all Danish military establishments. By succeeding in presenting ‘internal optimization’ as an outsourcing option (as opposed to the usual ‘make’ option) this case...... outsourcing strategies during a series of trials of strength, 2. develops the concept of ‘trial of strength’ for accounting and organization research by showing how ‘the rules of the game’ for the trials of strength can become challenged and controversial, 3. shows that, in addition to the pervasive role......Public sector outsourcing is a program within a suite of contemporary reforms mobilizing private enterprises in the belief of a more efficient public sector. Danish Armed Forces outsourcing of its facility services and management emerged as an option in 1991. Two strategic options developed: one...

High strength oil palm shell concrete beams reinforced with steel fibres

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S. Poh-Yap

2017-10-01

Full Text Available The utilization of lightweight oil palm shell to produce high strength lightweight sustainable material has led many researchers towards its commercialization as structural concrete. However, the low tensile strength of Oil Palm Shell Concrete (OPSC has hindered its development. This study aims to enhance the mechanical properties and flexural behaviours of OPSC by the addition of steel fibres of up to 3% by volume, to produce oil palm shell fibre-reinforced concrete (OPSFRC. The experimental results showed that the steel fibres significantly enhanced the mechanical properties of OPSFRC. The highest compressive strength, splitting tensile and flexural strengths of 55, 11.0 and 18.5 MPa, respectively, were achieved in the OPSFRC mix reinforced with 3% steel fibres. In addition, the flexural beam testing on OPSFRC beams with 3% steel fibres showed that the steel fibre reinforcement up to 3% produced notable increments in the moment capacity and crack resistance of OPSFRC beams, but accompanied by reduction in the ductility.

Strength of precast concrete shear joints reinforced with high-strength wire ropes

DEFF Research Database (Denmark)

Joergensen, Henrik B.; Hoang, Linh Cao; Hagsten, Lars German

2017-01-01

This paper concerns the in-plane shear strength of connections between precast concrete wall elements reinforced with looped high-strength wire ropes. The looped wire ropes are pre-installed in so-called ‘wire boxes’ which function as shear keys. Although only a small amount of research...... on the shear strength of such connections can be found in the literature, this type of connection is increasingly being used because wire ropes are much more construction-friendly than traditional U-bars. A rigid plastic upper bound model for the shear strength of wall connections reinforced with looped wire...... ropes that are pre-installed in wire boxes is presented along with test results on the shear strength of connections with double-wire boxes. It is shown that the plastic solution agrees well with both the obtained test results and results from previously conducted tests....

Relationships Between Lower-Body Muscle Structure and, Lower-Body Strength, Explosiveness and Eccentric Leg Stiffness in Adolescent Athletes

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Josh L. Secomb, Sophia Nimphius, Oliver R.L. Farley, Lina E. Lundgren, Tai T. Tran, Jeremy M. Sheppard

2015-12-01

Full Text Available The purpose of the present study was to determine whether any relationships were present between lower-body muscle structure and, lower-body strength, variables measured during a countermovement jump (CMJ and squat jump (SJ, and eccentric leg stiffness, in adolescent athletes. Thirty junior male (n = 23 and female (n = 7 surfing athletes (14.8 ± 1.7 y; 1.63 ± 0.09 m; 54.8 ± 12.1 kg undertook lower-body muscle structure assessment with ultrasonography and performed a; CMJ, SJ and an isometric mid-thigh pull (IMTP. In addition, eccentric leg stiffness was calculated from variables of the CMJ and IMTP. Moderate to very large relationships (r = 0.46-0.73 were identified between the thickness of the vastus lateralis (VL and lateral gastrocnemius (LG muscles, and VL pennation angle and; peak force (PF in the CMJ, SJ and IMTP. Additionally, moderate to large relationships (r = 0.37-0.59 were found between eccentric leg stiffness and; VL and LG thickness, VL pennation angle, and LG fascicle length, with a large relationship (r = 0.59 also present with IMTP PF. These results suggest that greater thickness of the VL and LG were related to improved maximal dynamic and isometric strength, likely due to increased hypertrophy of the extensor muscles. Furthermore, this increased thickness was related to greater eccentric leg stiffness, as the associated enhanced lower-body strength likely allowed for greater neuromuscular activation, and hence less compliance, during a stretch-shortening cycle.

The Influence of Green Infrastructure on Urban Resilience in Greater London

Science.gov (United States)

Oh, Yukyung

2017-04-01

, worthwhileness, happiness and anxiety. The correlation analysis outcomes can be divided into three levels such as Greater London as a whole, and Inner and Outer London. In Greater London, total area of green spaces has a strong relation with crime rates, and a less strong relation with number of jobs. Both socioeconomic indicators showed a negative trend along with the increase of open spaces. In terms of wellbeing indicators, the positive trend of life satisfaction, worthwhileness and happiness, and the negative trend of anxiety can be found in accordance with the increase of green coverage. In Inner London, job density and crime rates show a negative trend in accordance with the increase of total open space areas. And as contagion of open spaces is higher, the indicators of number of jobs, jobs density, and crime rates also showed an increase tendency. As for worthwhileness and happiness, it also showed a substantial correlation with contagion of open spaces. In Outer London, the correlation between job density and crime rates, and open space cannot be found, but the wellbeing indicators such as life satisfaction and worthwhileness show an increase trend along with larger green coverage.

The effect of strength training on the testosterone level in men

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Stanković Aleksandar

2013-01-01

Full Text Available Primary objective of this study was to provide the insight into the effects of strength training on the testosterone (TE level in men, as well as the mechanisms of anabolic effects of testosterone on human muscle apparatus, since it is known that one of the ways to increase muscle strength is through the increase of muscle mass (peripheral factor, and the basis of this process is the effect of TE. The collected data summarize the conclusions of a number of previous studies, out of which larger number of recently, and they relate to the effect of different methods of strength training (H - submaximal effort to failure, S - maximal effort, P - dynamic effort with equally applied total volume of load, and the effect of different rest periods in strength training on the level of TE in men. The presented results confirmed the claims that the H method is the most effective and reasonably called 'the method for muscle hypertrophy'. When it comes to rest periods, the ones that last for about 90 seconds proved optimal because this period had most influence on the level of lactic acid and catecholamines in blood which are considered to be the key factors for the increased secretion of TE (this hormone was included in a group of stress hormones as well. However, according to many authors, further examinations in this field are necessary in order to determine the causal link with greater certainty.

Evaluation of pH, ultimate tensile strength, and micro-shear bond strength of two self-adhesive resin cements

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Luciana Artioli COSTA

2014-01-01

Full Text Available The aim of this study was to evaluate the pH, ultimate tensile strength (UTS, and micro-shear bond strength (µSBS of two self-adhesive resin cements to enamel and dentin. Sound bovine incisors (n = 10 and two self-adhesive resin cements (i.e., RelyX U-100 and seT PP were used. The pH of the resin cements was measured using a pH-indicator paper (n = 3. Specimens for UTS were obtained from an hourglass-shaped mold. For µSBS, cylinders with internal diameter of 0.75 mm and height of 0.5 mm were bonded to the flat enamel and dentin surfaces. Bonded cylinders were tested in the shear mode using a loop wire. The fracture mode was also evaluated. The cement seT PP showed a low pH; U-100 showed significantly higher UTS (49.9 ± 2.0 than seT PP (40.0 ± 2.1 (p < 0.05 and high µSBS to enamel (10.7 ± 3.7. The lowest µSBS was found for seT PP to dentin (0.7 ± 0.6; seT PP to enamel (4.8 ± 1.7, and for U-100 to dentin (7.2 ± 1.9, showing an intermediate µSBS value (p < 0.05. Adhesive failure was the most frequently observed failure mode. The resin cement that presented the lowest pH and UTS also presented the lowest micro-shear bond strength to enamel and dentin.

The Effects of Industrial Protective Gloves and Hand Skin Temperatures on Hand Grip Strength and Discomfort Rating

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Mohamed Z. Ramadan

2017-12-01

Full Text Available Daily working activities and functions require a high contribution of hand and forearm muscles in executing grip force. To study the effects of wearing different gloves on grip strength, under a variety of hand skin temperatures, an assessment of the maximum grip strength was performed with 32 healthy male workers with a mean age (standard deviation of 30.44 (5.35 years wearing five industrial gloves at three hand skin temperatures. Their ages and anthropometric characteristics including body mass index (BMI, hand length, hand width, hand depth, hand palm, and wrist circumference were measured. The hand was exposed to different bath temperatures (5 °C, 25 °C, and 45 °C and hand grip strength was measured using a Jamar hydraulic hand dynamometer with and without wearing the gloves (chemical protection glove, rubber insulating glove, anti-vibration impact glove, cotton yarn knitted glove, and RY-WG002 working glove. The data were analyzed using the Shapiro–Wilk test, Pearson correlation coefficient, Tukey test, and analysis of variance (ANOVA of the within-subject design analysis. The results showed that wearing gloves significantly affected the maximum grip strength. Wearing the RY-WG002 working glove produced a greater reduction on the maximum grip when compared with the bare hand, while low temperatures (5 °C had a significant influence on grip when compared to medium (25 °C and high (45 °C hand skin temperatures. In addition, participants felt more discomfort in both environmental extreme conditions. Furthermore, they reported more discomfort while wearing neoprene, rubber, and RY-WG002 working gloves.

Effect of chlorhexidine application on the bond strength of resin core to axial dentin in endodontic cavity

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Yun-Hee Kim

2012-11-01

Full Text Available Objectives This study evaluated the influence of chlorhexidine (CHX on the microtensile bonds strength (µTBS of resin core with two adhesive systems to dentin in endodontic cavities. Materials and Methods Flat dentinal surfaces in 40 molar endodontic cavities were treated with self-etch adhesive system, Contax (DMG and total-etch adhesive system, Adper Single Bond 2 (3M ESPE after the following surface treatments: (1 Priming only (Contax, (2 CHX for 15 sec + rinsing + priming (Contax, (3 Etching with priming (Adper Single Bond 2, (4 Etching + CHX for 15 sec + rinsing + priming (Adper Single Bond 2. Resin composite build-ups were made with LuxaCore (DMG using a bulk method and polymerized for 40 sec. For each condition, half of specimens were submitted to µTBS after 24 hr storage and half of them were submitted to thermocycling of 10,000 cycles between 5℃ and 55℃ before testing. The data were analyzed using ANOVA and independent t-test at a significance level of 95%. Results CHX pre-treatment did not affect the bond strength of specimens tested at the immediate testing period, regardless of dentin surface treatments. However, after 10,000 thermocycling, all groups showed reduced bond strength. The amount of reduction was greater in groups without CHX treatments than groups with CHX treatment. These characteristics were the same in both self-etch adhesive system and total-etch adhesive system. Conclusions 2% CHX application for 15 sec proved to alleviate the decrease of bond strength of dentin bonding systems. No significant difference was shown in µTBS between total-etching system and self-etching system.

Semantic priming increases word frequency judgments: Evidence for the role of memory strength in frequency estimation.

Science.gov (United States)

Woltz, Dan J; Gardner, Michael K

2015-09-01

Previous research has demonstrated a systematic, nonlinear relationship between word frequency judgments and values from word frequency norms. This relationship could reflect a perceptual process similar to that found in the psychophysics literature for a variety of sensory phenomena. Alternatively, it could reflect memory strength differences that are expected for words of varying levels of prior exposure. Two experiments tested the memory strength explanation by semantically priming words prior to frequency judgments. Exposure to related word meanings produced a small but measurable increase in target word frequency ratings. Repetition but not semantic priming had a greater impact on low compared to high frequency words. These findings are consistent with a memory strength view of frequency judgments that assumes a distributed network with lexical and semantic levels of representation. Copyright © 2015 Elsevier B.V. All rights reserved.

Effects of cathodic protection on cracking of high-strength pipeline steels

Energy Technology Data Exchange (ETDEWEB)

Elboujdaini, M.; Revie, R. W.; Attard, M. [CANMET Materials Technology Laboratory, Ottawa, ON(Canada)], email: melboujd@nrcan.gc.ca

2010-07-01

Four strength levels of pipeline steels, ranging from X-70 to X-120, were compared to determine whether higher strength materials are more susceptible to hydrogen embrittlement under cathodic protection. Ductility was measured in a solution at four protection levels, going from no cathodic protection to 500 mV of overprotection. All four steels showed loss of ductility under cathodic protection. Under cathodic polarization, the loss of ductility increased with the strength of the steel and the activity of the potential. After slow-strain-rate experiments conducted in air and examination of fracture surfaces, it is concluded that application of cathodic potentials, cathodic overprotection, higher strength of steel, and exposure to aqueous solution are factors that decrease the ductility of steel. Hydrogen reduction seems to be an important factor in ductility reduction and fractures. Observations suggest that high-strength pipelines need better control of cathodic protection than lower-strength pipelines.

The effect of Nordic hamstring strength training on muscle architecture, stiffness, and strength.

Science.gov (United States)

Seymore, Kayla D; Domire, Zachary J; DeVita, Paul; Rider, Patrick M; Kulas, Anthony S

2017-05-01

Hamstring strain injury is a frequent and serious injury in competitive and recreational sports. While Nordic hamstring (NH) eccentric strength training is an effective hamstring injury-prevention method, the protective mechanism of this exercise is not understood. Strength training increases muscle strength, but also alters muscle architecture and stiffness; all three factors may be associated with reducing muscle injuries. The purpose of this study was to examine the effects of NH eccentric strength training on hamstring muscle architecture, stiffness, and strength. Twenty healthy participants were randomly assigned to an eccentric training group or control group. Control participants performed static stretching, while experimental participants performed static stretching and NH training for 6 weeks. Pre- and post-intervention measurements included: hamstring muscle architecture and stiffness using ultrasound imaging and elastography, and maximal hamstring strength measured on a dynamometer. The experimental group, but not the control group, increased volume (131.5 vs. 145.2 cm 3 , p hamstring strength. The NH intervention was an effective training method for muscle hypertrophy, but, contrary to common literature findings for other modes of eccentric training, did not increase fascicle length. The data suggest that the mechanism behind NH eccentric strength training mitigating hamstring injury risk could be increasing volume rather than increasing muscle length. Future research is, therefore, warranted to determine if muscle hypertrophy induced by NH training lowers future hamstring strain injury risk.

The binding of glucose to yeast hexokinase monomers is independent of ionic strength.

Science.gov (United States)

Mayes, E L; Hoggett, J G; Kellett, G L

1982-05-01

Hoggett & Kellett [Eur. J. Biochem. 66, 65-77 (1976)] have reported that the binding of glucose to the monomer of hexokinase PII isoenzyme is independent of ionic strength, in contrast to the subsequent claim of Feldman & Kramp [Biochemistry 17, 1541-1547 (1978)] that the binding is strongly dependent on ionic strength. Since measurements with native hexokinase P forms are complicated by the fact that the enzyme exists in a monomer-dimer association-dissociation equilibrium, we have now studied the binding of glucose to the proteolytically-modified S forms which are monomeric. At pH 8.5, the affinity of glucose for both SI and SII monomers is independent of salt concentration over the range of KCl concentrations 0-1.0 mol . dm-3 and is in good agreement with that of the corresponding P forms in both low and high salt. These observations confirm that the binding of glucose to hexokinase P monomers is independent of ionic strength and that the affinity of glucose for the hexokinase PII monomer is about an order of magnitude greater than that for the dimer.

Strength and agility skills of grade 1-learners: North-West child study ...

African Journals Online (AJOL)

Proficiency, second edition (BOT-2) was used to evaluate the children's strength and agility skills. The results showed meaningful gender differences with respect to the strength skills of the learners, since boys performed better in the standing long ...

Effects of Agar Gel Strength and Fat on Oral Breakdown, Volatile Release, and Sensory Perception Using in Vivo and in Vitro Systems.

Science.gov (United States)

Frank, Damian; Eyres, Graham T; Piyasiri, Udayasika; Cochet-Broch, Maeva; Delahunty, Conor M; Lundin, Leif; Appelqvist, Ingrid M

2015-10-21

The density and composition of a food matrix affect the rates of oral breakdown and in-mouth flavor release as well as the overall sensory experience. Agar gels of increasing concentration (1.0, 1.7, 2.9, and 5% agarose) with and without added fat (0, 2, 5, and 10%) were spiked with seven aroma volatiles. Differences in oral processing and sensory perception were systematically measured by a trained panel using a discrete interval time intensity method. Volatile release was measured in vivo and in vitro by proton transfer reaction mass spectrometry. Greater oral processing was required as agar gel strength increased, and the intensity of flavor-related sensory attributes decreased. Volatile release was inversely related to gel strength, showing that physicochemical phenomena were the main mechanisms underlying the perceived sensory changes. Fat addition reduced the amount of oral processing and had differential effects on release, depending on the fat solubility or lipophilicity of the volatiles.

Effects of Low- vs. High-Load Resistance Training on Muscle Strength and Hypertrophy in Well-Trained Men.

Science.gov (United States)

Schoenfeld, Brad J; Peterson, Mark D; Ogborn, Dan; Contreras, Bret; Sonmez, Gul T

2015-10-01

The purpose of this study was to compare the effect of low- versus high-load resistance training (RT) on muscular adaptations in well-trained subjects. Eighteen young men experienced in RT were matched according to baseline strength and then randomly assigned to 1 of 2 experimental groups: a low-load RT routine (LL) where 25-35 repetitions were performed per set per exercise (n = 9) or a high-load RT routine (HL) where 8-12 repetitions were performed per set per exercise (n = 9). During each session, subjects in both groups performed 3 sets of 7 different exercises representing all major muscles. Training was performed 3 times per week on nonconsecutive days, for a total of 8 weeks. Both HL and LL conditions produced significant increases in thickness of the elbow flexors (5.3 vs. 8.6%, respectively), elbow extensors (6.0 vs. 5.2%, respectively), and quadriceps femoris (9.3 vs. 9.5%, respectively), with no significant differences noted between groups. Improvements in back squat strength were significantly greater for HL compared with LL (19.6 vs. 8.8%, respectively), and there was a trend for greater increases in 1 repetition maximum (1RM) bench press (6.5 vs. 2.0%, respectively). Upper body muscle endurance (assessed by the bench press at 50% 1RM to failure) improved to a greater extent in LL compared with HL (16.6 vs. -1.2%, respectively). These findings indicate that both HL and LL training to failure can elicit significant increases in muscle hypertrophy among well-trained young men; however, HL training is superior for maximizing strength adaptations.

Interaction strength combinations and the overfishing of a marine food web.

Science.gov (United States)

Bascompte, Jordi; Melián, Carlos J; Sala, Enric

2005-04-12

The stability of ecological communities largely depends on the strength of interactions between predators and their prey. Here we show that these interaction strengths are structured nonrandomly in a large Caribbean marine food web. Specifically, the cooccurrence of strong interactions on two consecutive levels of food chains occurs less frequently than expected by chance. Even when they occur, these strongly interacting chains are accompanied by strong omnivory more often than expected by chance. By using a food web model, we show that these interaction strength combinations reduce the likelihood of trophic cascades after the overfishing of top predators. However, fishing selectively removes predators that are overrepresented in strongly interacting chains. Hence, the potential for strong community-wide effects remains a threat.

Compressive Strength of Volcanic Ash/Ordinary Portland Cement Laterized Concrete

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Olusola K. O.

2010-01-01

Full Text Available This study investigates the effect of partial replacement of cement with volcanic ash (VA on the compressive strength of laterized concrete. A total of 192 cubes of 150mm dimensions were cast and cured in water for 7, 14, 21, and 28 days of hydration with cement replacement by VA and sand replacement by laterite both ranging from 0 to 30% respectively, while a control mix of 28-day target strength of 25 N/mm2 was adopted. The results show that the density and compressive strength of concrete decreased with increase in volcanic ash content. The 28-day, density dropped from 2390 kg/m3 to 2285 kg/m3 (i.e. 4.4% loss and the compressive strength from 25.08 N/mm2 to 17.98 N/mm2 (i.e. 28% loss for 0-30% variation of VA content with no laterite introduced. The compressive strength also decreased with increase in laterite content; the strength of the laterized concrete however increases as the curing age progresses.

The theoretical tensile strength of fcc crystals predicted from shear strength calculations

International Nuclear Information System (INIS)

Cerny, M; Pokluda, J

2009-01-01

This work presents a simple way of estimating uniaxial tensile strength on the basis of theoretical shear strength calculations, taking into account its dependence on a superimposed normal stress. The presented procedure enables us to avoid complicated and time-consuming analyses of elastic stability of crystals under tensile loading. The atomistic simulations of coupled shear and tensile deformations in cubic crystals are performed using first principles computational code based on pseudo-potentials and the plane wave basis set. Six fcc crystals are subjected to shear deformations in convenient slip systems and a special relaxation procedure controls the stress tensor. The obtained dependence of the ideal shear strength on the normal tensile stress seems to be almost linearly decreasing for all investigated crystals. Taking these results into account, the uniaxial tensile strength values in three crystallographic directions were evaluated by assuming a collapse of the weakest shear system. Calculated strengths for and loading were found to be mostly lower than previously calculated stresses related to tensile instability but rather close to those obtained by means of the shear instability analysis. On the other hand, the strengths for loading almost match the stresses related to tensile instability.

Reading About the Flu Online: How Health-Protective Behavioral Intentions Are Influenced by Media Multitasking, Polychronicity, and Strength of Health-Related Arguments.

Science.gov (United States)

Kononova, Anastasia; Yuan, Shupei; Joo, Eunsin

2017-06-01

As health organizations increasingly use the Internet to communicate medical information and advice (Shortliffe et al., 2000; World Health Organization, 2013), studying factors that affect health information processing and health-protective behaviors becomes extremely important. The present research applied the elaboration likelihood model of persuasion to explore the effects of media multitasking, polychronicity (preference for multitasking), and strength of health-related arguments on health-protective behavioral intentions. Participants read an online article about influenza that included strong and weak suggestions to engage in flu-preventive behaviors. In one condition, participants read the article and checked Facebook; in another condition, they were exposed only to the article. Participants expressed greater health-protective behavioral intentions in the media multitasking condition than in the control condition. Strong arguments were found to elicit more positive behavioral intentions than weak arguments. Moderate and high polychronics showed greater behavioral intentions than low polychronics when they read the article in the multitasking condition. The difference in intentions to follow strong and weak arguments decreased for moderate and high polychronics. The results of the present study suggest that health communication practitioners should account for not only media use situations in which individuals typically read about health online but also individual differences in information processing, which puts more emphasis on the strength of health-protective suggestions when targeting light multitaskers.

Flexural properties and impact strength of denture base resins reinforced with micronized glass flakes

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Ronak H Choksi

2016-01-01

Conclusion: Flexural strength of unmodified PMMA denture base resin decreases with increase in the concentration of glass flakes. Impact strength does not show any significant change at 5% concentration of glass flakes and impact strength significantly reduces with the addition of glass flakes in 10% and 20%.

Inpatient rehabilitation improves functional capacity, peripheral muscle strength and quality of life in patients with community-acquired pneumonia: a randomised trial.

Science.gov (United States)

José, Anderson; Dal Corso, Simone

2016-04-01

Among people who are hospitalised for community-acquired pneumonia, does an inpatient exercise-based rehabilitation program improve functional outcomes, symptoms, quality of life and length of hospital stay more than a respiratory physiotherapy regimen? Randomised trial with concealed allocation, intention-to-treat analysis and blinding of some outcomes. Forty-nine adults hospitalised for community-acquired pneumonia. The experimental group (n=32) underwent a physical training program that included warm-up, stretching, peripheral muscle strength training and walking at a controlled speed for 15 minutes. The control group (n=17) underwent a respiratory physiotherapy regimen that included percussion, vibrocompression, respiratory exercises and free walking. The intervention regimens lasted 8 days. The primary outcome was the Glittre Activities of Daily Living test, which assesses the time taken to complete a series of functional tasks (eg, rising from a chair, walking, stairs, lifting and bending). Secondary outcomes were distance walked in the incremental shuttle walk test, peripheral muscle strength, quality of life, dyspnoea, lung function, C-reactive protein and length of hospital stay. Measures were taken 1 day before and 1 day after the intervention period. There was greater improvement in the experimental group than in the control group on the Glittre Activities of Daily Living test (mean between-group difference 39 seconds, 95% CI 20 to 59) and the incremental shuttle walk test (mean between-group difference 130 m, 95% CI 77 to 182). There were also significantly greater improvements in quality of life, dyspnoea and peripheral muscle strength in the experimental group than in the control group. There were no between-group differences in lung function, C-reactive protein or length of hospital stay. The improvement in functional outcomes after an inpatient rehabilitation program was greater than the improvement after standard respiratory physiotherapy. The

Patient expectations predict greater pain relief with joint arthroplasty.

Science.gov (United States)

Gandhi, Rajiv; Davey, John Roderick; Mahomed, Nizar

2009-08-01

We examined the relationship between patient expectations of total joint arthroplasty and functional outcomes. We surveyed 1799 patients undergoing primary hip or knee arthroplasty for demographic data and Western Ontario McMaster University Osteoarthritis Index scores at baseline, 3 months, and 1 year of follow-up. Patient expectations were determined with 3 survey questions. The patients with the greatest expectations of surgery were younger, male, and had a lower body mass index. Linear regression modeling showed that a greater expectation of pain relief with surgery independently predicted greater reported pain relief at 1 year of follow-up, adjusted for all relevant covariates (P relief after joint arthroplasty is an important predictor of outcomes at 1 year.

Striated muscle fiber size, composition and capillary density in diabetes in relation to neuropathy and muscle strength

DEFF Research Database (Denmark)

Andreassen, Christer Swan; Jensen, Jacob Malte; Jakobsen, Johannes

2014-01-01

study was to evaluate histologic properties and capillarization of diabetic skeletal muscle in relation to DPN and muscle strength. METHODS: Twenty type 1 and 20 type 2 diabetic (T1D and T2D, respectively) patients underwent biopsy of the gastrocnemic muscle, isokinetic dynamometry at the ankle...... between muscle fiber diameter, muscle fiber type distribution, or capillary density and degree of neuropathy or muscle strength for either patient group. Muscle fiber diameter and the proportion of Type II fibers were greater for T1D patients than both T2D patients and controls. The T2D patients had fewer...

Kinematics and kinetics of the bench-press and bench-pull exercises in a strength-trained sporting population.

Science.gov (United States)

Pearson, Simon N; Cronin, John B; Hume, Patria A; Slyfield, David

2009-09-01

Understanding how loading affects power production in resistance training is a key step in identifying the most optimal way of training muscular power - an essential trait in most sporting movements. Twelve elite male sailors with extensive strength-training experience participated in a comparison of kinematics and kinetics from the upper body musculature, with upper body push (bench press) and pull (bench pull) movements performed across loads of 10-100% of one repetition maximum (1RM). 1RM strength and force were shown to be greater in the bench press, while velocity and power outputs were greater for the bench pull across the range of loads. While power output was at a similar level for the two movements at a low load (10% 1RM), significantly greater power outputs were observed for the bench pull in comparison to the bench press with increased load. Power output (Pmax) was maximized at higher relative loads for both mean and peak power in the bench pull (78.6 +/- 5.7% and 70.4 +/- 5.4% of 1RM) compared to the bench press (53.3 +/- 1.7% and 49.7 +/- 4.4% of 1RM). Findings can most likely be attributed to differences in muscle architecture, which may have training implications for these muscles.

High-strength mineralized collagen artificial bone

Science.gov (United States)

Qiu, Zhi-Ye; Tao, Chun-Sheng; Cui, Helen; Wang, Chang-Ming; Cui, Fu-Zhai

2014-03-01

Mineralized collagen (MC) is a biomimetic material that mimics natural bone matrix in terms of both chemical composition and microstructure. The biomimetic MC possesses good biocompatibility and osteogenic activity, and is capable of guiding bone regeneration as being used for bone defect repair. However, mechanical strength of existing MC artificial bone is too low to provide effective support at human load-bearing sites, so it can only be used for the repair at non-load-bearing sites, such as bone defect filling, bone graft augmentation, and so on. In the present study, a high strength MC artificial bone material was developed by using collagen as the template for the biomimetic mineralization of the calcium phosphate, and then followed by a cold compression molding process with a certain pressure. The appearance and density of the dense MC were similar to those of natural cortical bone, and the phase composition was in conformity with that of animal's cortical bone demonstrated by XRD. Mechanical properties were tested and results showed that the compressive strength was comparable to human cortical bone, while the compressive modulus was as low as human cancellous bone. Such high strength was able to provide effective mechanical support for bone defect repair at human load-bearing sites, and the low compressive modulus can help avoid stress shielding in the application of bone regeneration. Both in vitro cell experiments and in vivo implantation assay demonstrated good biocompatibility of the material, and in vivo stability evaluation indicated that this high-strength MC artificial bone could provide long-term effective mechanical support at human load-bearing sites.

Strength variability of single flax fibres

DEFF Research Database (Denmark)

Aslan, Mustafa; Chinga-Carrasco, G.; Sørensen, Bent F.

2011-01-01

(linear and nonlinear) of the fibres are found to be correlated with the amount of defects. The linear stress–strain curves tend to show a higher tensile strength, a higher Young’s modulus, and a lower strain to failure than the nonlinear curves. Finally, the fibres are found to fracture by a complex...

Testing resonating vector strength: Auditory system, electric fish, and noise

Science.gov (United States)

Leo van Hemmen, J.; Longtin, André; Vollmayr, Andreas N.

2011-12-01

Quite often a response to some input with a specific frequency ν○ can be described through a sequence of discrete events. Here, we study the synchrony vector, whose length stands for the vector strength, and in doing so focus on neuronal response in terms of spike times. The latter are supposed to be given by experiment. Instead of singling out the stimulus frequency ν○ we study the synchrony vector as a function of the real frequency variable ν. Its length turns out to be a resonating vector strength in that it shows clear maxima in the neighborhood of ν○ and multiples thereof, hence, allowing an easy way of determining response frequencies. We study this "resonating" vector strength for two concrete but rather different cases, viz., a specific midbrain neuron in the auditory system of cat and a primary detector neuron belonging to the electric sense of the wave-type electric fish Apteronotus leptorhynchus. We show that the resonating vector strength always performs a clear resonance correlated with the phase locking that it quantifies. We analyze the influence of noise and demonstrate how well the resonance associated with maximal vector strength indicates the dominant stimulus frequency. Furthermore, we exhibit how one can obtain a specific phase associated with, for instance, a delay in auditory analysis.

Static and Dynamic Handgrip Strength Endurance: Test-Retest Reproducibility.

Science.gov (United States)

Gerodimos, Vassilis; Karatrantou, Konstantina; Psychou, Dimitra; Vasilopoulou, Theodora; Zafeiridis, Andreas

2017-03-01

This study investigated the reliability of static and dynamic handgrip strength endurance using different protocols and indicators for the assessment of strength endurance. Forty young, healthy men and women (age, 18-22 years) performed 2 handgrip strength endurance protocols: a static protocol (sustained submaximal contraction at 50% of maximal voluntary contraction) and a dynamic one (8, 10, and 12 maximal repetitions). The participants executed each protocol twice to assess the test-retest reproducibility. Total work and total time were used as indicators of strength endurance in the static protocol; the strength recorded at each maximal repetition, the percentage change, and fatigue index were used as indicators of strength endurance in the dynamic protocol. The static protocol showed high reliability irrespective of sex and hand for total time and work. The 12-repetition dynamic protocol exhibited moderate-high reliability for repeated maximal repetitions and percentage change; the 8- and 10-repetition protocols demonstrated lower reliability irrespective of sex and hand. The fatigue index was not a reliable indicator for the assessment of dynamic handgrip endurance. Static handgrip endurance can be measured reliably using the total time and total work as indicators of strength endurance. For the evaluation of dynamic handgrip endurance, the 12-repetition protocol is recommended, using the repeated maximal repetitions and percentage change as indicators of strength endurance. Practitioners should consider the static (50% maximal voluntary contraction) and dynamic (12 repeated maximal repetitions) protocols as reliable for the assessment of handgrip strength endurance. The evaluation of static endurance in conjunction with dynamic endurance would provide more complete information about hand function. Copyright © 2017 American Society for Surgery of the Hand. Published by Elsevier Inc. All rights reserved.

Spacing of Imbricated Thrust Faults and the Strength of Thrust-Belts and Accretionary Wedges

Science.gov (United States)

Ito, G.; Regensburger, P. V.; Moore, G. F.

2017-12-01

The pattern of imbricated thrust blocks is a prominent characteristic of the large-scale structure of thrust-belts and accretionary wedges around the world. Mechanical models of these systems have a rich history from laboratory analogs, and more recently from computational simulations, most of which, qualitatively reproduce the regular patterns of imbricated thrusts seen in nature. Despite the prevalence of these patterns in nature and in models, our knowledge of what controls the spacing of the thrusts remains immature at best. We tackle this problem using a finite difference, particle-in-cell method that simulates visco-elastic-plastic deformation with a Mohr-Coulomb brittle failure criterion. The model simulates a horizontal base that moves toward a rigid vertical backstop, carrying with it an overlying layer of crust. The crustal layer has a greater frictional strength than the base, is cohesive, and is initially uniform in thickness. As the layer contracts, a series of thrust blocks immerge sequentially and form a wedge having a mean taper consistent with that predicted by a noncohesive, critical Coulomb wedge. The widths of the thrust blocks (or spacing between adjacent thrusts) are greatest at the front of the wedge, tend to decrease with continued contraction, and then tend toward a pseudo-steady, minimum width. Numerous experiments show that the characteristic spacing of thrusts increases with the brittle strength of the wedge material (cohesion + friction) and decreases with increasing basal friction for low (laws that will illuminate the basic physical processes controlling systems, as well as allow researchers to use observations of thrust spacing as an independent constraint on the brittle strength of wedges as well as their bases.

Cardiorespiratory fitness and muscle strength in pancreatic cancer patients.

Science.gov (United States)

Clauss, Dorothea; Tjaden, Christine; Hackert, Thilo; Schneider, Lutz; Ulrich, Cornelia M; Wiskemann, Joachim; Steindorf, Karen

2017-09-01

Cancer patients frequently experience reduced physical fitness due to the disease itself as well as treatment-related side effects. However, studies on physical fitness in pancreatic cancer patients are missing. Therefore, we assessed cardiorespiratory fitness and muscle strength of pancreatic cancer patients. We included 65 pancreatic cancer patients, mostly after surgical resection. Cardiorespiratory fitness was assessed using cardiopulmonary exercise testing (CPET) and 6-min walk test (6MWT). Hand-held dynamometry was used to evaluate isometric muscle strength. Physical fitness values were compared to reference values of a healthy population. Associations between sociodemographic and clinical variables with patients' physical fitness were analyzed using multiple regression models. Cardiorespiratory fitness (VO 2 peak, 20.5 ± 6.9 ml/min/kg) was significantly lower (-24%) compared to healthy reference values. In the 6MWT pancreatic cancer patients nearly reached predicted values (555 vs. 562 m). Maximal voluntary isometric contraction (MVIC) of the upper (-4.3%) and lower extremities (-13.8%) were significantly lower compared to reference values. Overall differences were larger in men than those in women. Participating in regular exercise in the year before diagnosis was associated with greater VO 2 peak (p fitness with regard to both cardiorespiratory function and isometric muscle strength, already in the early treatment phase (median 95 days after surgical resection). Our findings underline the need to investigate exercise training in pancreatic cancer patients to counteract the loss of physical fitness.

The influence of main bar corrosion on bond strength in selfcompacting concrete

Science.gov (United States)

Ayop, S. S.; Emhemed, A. N. K.; Jamaluddin, N.; Sadikin, A.

2017-11-01

The experimental study was conducted to determine the influence of main bar corrosion on bond strength in self-compacting concrete (SCC). A total 16 tension pullout tests specimens reinforced with 10 mm and 14 mm diameter bar were used for the bond strength test. The properties of SCC were determined from the slump flow, T50cm, V-funnel and L box test. Reinforcing bars in the concrete were submitted to impressed current to accelerate the corrosion of the bar. It was found that the relationship between bond strength and concrete strength in un-corroded specimens differed from that of corroded specimens set in high-strength concrete because of brittleness in the corroded specimens, which caused a sudden loss of bond strength. The results revealed that specimens of un-corroded and corroded showed a higher percentage of bond strength degradation during the pullout tests.

Experimental knee joint pain during strength training and muscle strength gain in healthy subjects