Nonlinear elasticity of stiff biopolymers connected by flexible linkers

Networks of the biopolymer actin, cross-linked by the compliant protein filamin, form soft gels. They can, however, withstand large shear stresses due to their pronounced nonlinear elastic behavior. The nonlinear elasticity can be controlled by varying the number of cross-links per actin filament. We propose and test a model of rigid filaments decorated by multiple flexible linkers that is in quantitative agreement with experiment. This allows us to estimate loads on individual cross-links, which we find to be less than 10 pN. © 2009 The American Physical Society

Effect of a short message service (SMS) intervention on adherence to a physiotherapist-prescribed home exercise program for people with knee osteoarthritis and obesity: protocol for the ADHERE randomised controlled trial

Background Knee osteoarthritis (OA) is a highly prevalent condition. People with knee OA often have other co-morbidities such as obesity. Exercise is advocated in all clinical guidelines for the management of knee OA. It is often undertaken as a home-based program, initially prescribed by a physiotherapist or other qualified health care provider. However, adherence to home-based exercise is often poor, limiting its ability to meaningfully change clinical symptoms of pain and/or physical function. While the efficacy of short message services (SMS) to promote adherence to a range of health behaviours has been demonstrated, its ability to promote home exercise adherence in people with knee OA has not been specifically evaluated. Hence, this trial is investigating whether the addition of an SMS intervention to support adherence to prescribed home-based exercise is more effective than no SMS on self-reported measures of exercise adherence. Methods We are conducting a two-arm parallel-design, assessor-and participant-blinded randomised controlled trial (ADHERE) in people with knee OA and obesity. The trial is enrolling participants exiting from another randomised controlled trial, the TARGET trial, where participants are prescribed a 12-week home-based exercise program (either weight bearing functional exercise or non-weight bearing quadriceps strengthening exercise) for their knee by a physiotherapist and seen five times over the 12 weeks for monitoring and supervision. Following completion of outcome measures for the TARGET trial, participants are immediately enrolled into the ADHERE trial. Participants are asked to continue their prescribed home exercise program unsupervised three times a week for 24-weeks and are randomly allocated to receive a behaviour change theory-informed SMS intervention to support home exercise adherence or to have no SMS intervention. Outcomes are measured at baseline and 24-weeks. Primary outcomes are self-reported adherence measures. Secondary outcomes include self-reported measures of knee pain, physical function, quality-of-life, physical activity, self-efficacy, kinesiophobia, pain catastrophising, participant-perceived global change and an additional adherence measure. Discussion Findings will provide new information into the potential of SMS to improve longer-term exercise adherence and ultimately enhance exercise outcomes in knee OA

Capillary micromechanics: Measuring the elasticity of microscopic soft objects

We present a simple method for accessing the elastic properties of microscopic deformable particles. This method is based on measuring the pressure-induced deformation of soft particles as they are forced through a tapered glass microcapillary. It allows us to determine both the compressive and the shear modulus of a deformable object in one single experiment. Measurements on a model system of poly-acrylamide microgel particles exhibit excellent agreement with measurements on bulk gels of identical composition. Our approach is applicable over a wide range of mechanical properties and should thus be a valuable tool for the characterization of a variety of soft and biological materials

Effect of hair shearing on live performance and carcass traits of growing rabbits under hot ambient temperature

[EN] The aim of the study was to examine the effect of hair shearing in growing rabbits reared at high ambient temperature. The live performance and carcass traits of growing rabbits reared at 20°C (not sheared, C, n=50) or at 28°C (not sheared, H, n=50, or sheared at 5, 7 and 9 wk, HS, n=50) were compared. The ambient temperature and relative humidity were 20.5±1.1°C and 54±11% in the 20°C room and 28.8±0.2°C and 35±8% in 28°C room, respectively. Feed intake of H and HS groups decreased by 29.0 and 20.4%, respectively, compared to C rabbits (P<0.001). The same data for weight gain were 24.6 and 16.9% (P<0.001), and for body weight at 12 wk were 16.8 and 11.5% (P<0.001). At the same time, the feed conversion ratio improved (C: 3.53, HS: 3.34, H: 3.31; P<0.001). Nevertheless, the mortality rate of rabbits was not affected by the studied treatment and was overall low (0-4%). No differences were observed in dressing out percentages either (ratio of chilled carcass (CC) to the slaughter weight: 61.6-61.9%). The ratio of liver to CC differed among the experimental groups, with the highest value recorded in C group and the lowest in H group; HS rabbits showed intermediate results (C: 4.86%, HS: 4.27%, H: 3.91%; P<0.001). Lower ratios of fat deposits to reference carcass were also observed in rabbits kept at high ambient temperature (perirenal fat: C: 2.59%, HS: 1.82%, H: 1.60%; P<0.001; scapular fat: C: 0.89%, HS: 0.66%, H: 0.51%; P<0.001). It can be concluded that the negative effect of higher ambient temperature (28 vs. 20°C) on production in growing rabbits can be reduced significantly by hair shearing.En este agradecimieento: "The work was supported by the GINOP-2.3.4-15-2016-00005 project. Publication was supported by the EFOP-3.6.3-VEKOP-16–2017–00008 project. The project is co-funded by the European Union and the European Social Fund"Matics, Z.; Kasza, R.; Gerencsér, Z.; Radnai, I.; Dalle Zotte, A.; Cullere, M.; Szendrő, Z. (2020). Effect of hair shearing on live performance and carcass traits of growing rabbits under hot ambient temperature. World Rabbit Science. 28(3):161-167. https://doi.org/10.4995/wrs.2020.13164OJS161167283Balnave D. 1972. The effect of temperature and length of exposure on liver composition and hepatic lipogenic enzyme activity in the immature male chick (Gallus domesticus). Comp. Biochem. Physiol., 438: 999-1007. https://doi.org/10.1016/0305-0491(72)90244-1Blasco A., Ouhayoun J. 1996. Harmonization of criteria and terminology in rabbit meat research. Revised proposal. World Rabbit Sci., 4: 93-99. https://doi.org/10.4995/wrs.1996.278Chiericato G.M., Rizzi C., Rostellato V. 1993. Effect of genotype and environmental temperature on performance of the young meat rabbit. World Rabbit Sci., 1: 119-125. https://doi.org/10.4995/wrs.1993.204Chiericato G.M., Ravarotto L., Rizzi R. 1994. Study of the metabolic profile of rabbits in relation to two different environmental temperatures. World Rabbit Sci., 2: 153-160. https://doi.org/10.4995/wrs.1994.232Chiericato G.M., Rizzi C., Rostellato V. 1996. Growth and slaughtering performance of three rabbit genotypes under different environmental conditions. Ann. Zootech., 45: 311-318. https://doi.org/10.1051/animres:19960403Deltoro J., López A.M. 1986. Development of commercial characteristics of rabbit carcasses during growth. Livest. Prod. Sci., 15: 271-283. https://doi.org/10.1016/0301-6226(86)90034-5EC 2010. Directive 2010/63/EU of the European Parliament and of the Council of 22 September 2010 on the protection of animals used for scientific purposes. Official Journal of the European Union L276: 33-79.Fernández-Carmona J., Cervera C., Sabater C., Blas E. 1995. Effect of diet composition on the production of rabbit breeding does housed in a traditional building and at 30°C. Anim. Feed Sci. Technol., 52: 289-297. https://doi.org/10.1016/0377-8401(94)00715-LFinzi A., Morera P., Kuzminsky G. 1992. Effect of shearing on rabbit bucks performances in hot ambient conditions. J. Appl. Rabbit Res., 15: 489-494.Fuquay J.W. 1981. Heat stress as it affects animal production. J. Anim. Sci., 52: 164-174. https://doi.org/10.2527/jas1981.521164xHermes I.H., Ahmed B.M., Khalil M.H., Salah M.S., Al-Homidan A.A. 1999. Growth performance, nutrients utilization and carcass traits of growing Californian rabbits raised under different ambient temperatures. Egypt. J. Rabbit Sci., 9: 117-138.Jackson R., Rogers A.D, Lukefahr S.D. 2006. Effects of the naked gene on postweaning performance and thermotolerance characters in fryer rabbits: Final results. World Rabbit Sci., 14: 147-155. https://doi.org/10.4995/wrs.2006.559Kovitvadhi A., Chundang P., Thongprajukaew K., Tirawattanawanich C. 2019. Effects of different ambient temperatures on growth performances, digestibility, carcass traits and meat chemical components in fattening rabbits. J. Agriculture, 35: 495-502.Lebas F., Ouhayoun J. 1987. Incidence du niveau protéique de l'aliment, de milieu d'élevage et de la saison sur la croissance et les qualités bouchéres du lapin. Ann. Zootech., 36: 421-432. https://doi.org/10.1051/animres:19870406Lebas F., Coudert P., de Rochambeau H., Thébault R.G. 1997. The rabbit: husbandry, health and production. FAO Anim. Prod. and Health Series No. 21Lukefahr S.D., Ruiz-Feria C.A. 2003. Rabbit growth performance in a subtropical and semi-arid environment: Effects of fur clipping, ear length, and body temperature. Livest. Res. Rural Devel. 15: 2. Available at http://www.cipav.org.co/lrrd/lrrd15/2/luke152.htm Accessed October 2019.Marai I.F.M., Habeeb A.A.M., Gad A.E. 2002. Rabbits' productive, reproductive and physiological performance traits as affected by heat stress: a review. Livest. Prod. Sci., 78: 71-90. https://doi.org/10.1016/S0301-6226(02)00091-XMaya-Soriano M.J., Taberner E., Sabes-Alsina M., Ramon J., Rafel O., Tusell L., Piles M., López-Béjar M. 2015. Daily exposure to summer temperatures affects the motile subpopulation structure of epididymal sperm cells but not male fertility in an in vivo rabbit model. Theriogenology, 84: 384-389. https://doi.org/10.1016/j.theriogenology.2015.03.033Metzger Sz. 2006. Examination on carcass traits and meat quality of rabbit. (in Hung.) Doctoral (Ph.D.) dissertation. pp. 135.NASA https://climate.nasa.gov/Perez J.M., Lebas F., Gidenne T., Maertens L., Xiccato G., Parigi-Bini R., Dalle Zotte A., Cossu M.E., Carazzolo A., Villamide M.J., Carabaño R., Fraga M.J., Ramos M.A., Cervera C., Blas E., Fernández J., Falcão-e-Cunha L., Bengala Freire J. 1995. European reference method for in vivo determination of diet digestibility in rabbits. World Rabbit Sci. 3: 41-43. https://doi.org/10.4995/wrs.1995.239Renaudeau D., Collin A., Yahav S., de Basilio V., Gourdine J.L., Collier R.J. 2012. Adaptation to hot climate and strategies to alleviate heat stress in livestock production. Animal, 6: 707-728. https://doi.org/10.1017/S1751731111002448SAS Version 9.4. 2014. SAS Institute Inc; Cary, NC. Schlolaut W. 1995. Das grosse Buch vom Kaninchen. DLG-Verlag, Frankfurt am Main.Stephan E. 1980. The influence of environmental temperatures on meat rabbits of different breeds. Commercial Rabbit, 8: 12-15.Szendrő Zs., Rashwan R.R., Biró-Németh E., Radnai I., Orova Z. 2007. Effect of shearing of hair in summer on production of rabbit does. Acta Agr. Kapos., 11: 37-42.Szendrő Zs., Papp Z., Kustos K. 2018. Effect of ambient temperature and restricted feeding on the production of rabbit does and their kits. Acta Agr. Kapos., 22: 1-17. https://doi.org/10.31914/aak.2272Verga M., Luzi F., Carenzi C., 2007. Effects of husbandry and management systems on physiology and behaviour of farmed and laboratory rabbits. Horm. Behav., 52, 122-129. https://doi.org/10.1016/j.yhbeh.2007.03.024Zeferino P.C., Moura T.M.A.S.A., Fernandes S., Kanayama S.J., Scapinello C., Sartori R.J. 2011. Genetic group × ambient temperature interaction effects on physiological responses and growth performance of rabbits. Livest. Sci., 140: 177-183. https://doi.org/10.1016/j.livsci.2011.03.02

Visualizing the strain field in semiflexible polymer networks: strain fluctuations and nonlinear rheology of F-actin gels

We image semi-flexible polymer networks under shear at the micrometer scale. By tracking embedded probe particles, we determine the local strain field, and directly measure its uniformity, or degree of affineness, on scales of 2-100 micron. The degree of nonaffine strain depends on polymer length and crosslink density, consistent with theoretical predictions. We also find a direct correspondence between the uniformity of the microscale strain and the nonlinear elasticity of the networks in the bulk.Comment: 9 pages (double-spaced) of text, 4 figures + 1 supplementary figur

Technology versus tradition: a non-inferiority trial comparing video to face-to-face consultations with a physiotherapist for people with knee osteoarthritis. Protocol for the PEAK randomised controlled trial.

BACKGROUND: Knee osteoarthritis (OA) is a global problem that causes significant pain and physical dysfunction, substantially impacting on quality of life and imposing enormous cost to the healthcare system. Exercise is pivotal to OA management, yet uptake by people with knee OA is inadequate. Limited access to appropriately skilled health professionals, such as physiotherapists, for prescription of an exercise program and support with exercise is a major barrier to optimal care. Internet-enabled video consultations permit widespread reach. However, services offering video consultations with physiotherapists for musculoskeletal conditions are scant in Australia where there is typically no Government or private health insurer funding for such services. The paucity of robust evidence demonstrating video consultations with physiotherapists are clinically effective, safe and cost-effective for knee OA is hampering implementation of, and willingness of healthcare policymakers to pay for, these services. METHODS: This is an assessor- and participant-blinded, two-arm, pragmatic, comparative effectiveness non-inferiority randomised controlled trial (RCT) conducted in Australia. We are recruiting 394 people from the community with chronic knee pain consistent with a clinical diagnosis of knee OA. Participants are randomly allocated to receive physiotherapy care via i) video-conferencing or; ii) face-to-face consultations. Participants are provided five consultations (30-45 min each) with a physiotherapist over 3 months for prescription of a home-based strengthening exercise program (to be conducted independently at home) and physical activity plan, as well as OA education. Participants in both groups are provided with educational booklets and simple exercise equipment via post. The co-primary outcomes are change in self-reported i) knee pain on walking; and ii) physical function, with a primary end-point of 3 months and a secondary end-point of 9 months. Secondary outcomes include changes in other clinical outcomes (health-related quality of life; therapeutic relationship; global ratings of change; satisfaction with care; self-efficacy; physical activity levels), time and financial costs of attending consultations, healthcare usage and convenience. Non-inferiority will be assessed using the per-protocol dataset. DISCUSSION: Findings will determine if video consultations with physiotherapists are non-inferior to traditional face-to-face consultations for management of people with knee OA. TRIAL REGISTRATION: Australian New Zealand Clinical Trials Registry, ACTRN12619001240134. http://www.anzctr.org.au/Trial/Registration/TrialReview.aspx?id=377672&isReview=true

Use and abuse of dietary supplements for adolescents — Results of a survey among Hungarian recreational athletes

Consumption of dietary supplements (DS) has been showing a persistent, rapidly growing tendency all over the world. A new branch has been created on the borderline of food and pharmaceutical industries. It is a general tendency that the policy and regulation towards the products of this branch are lagging far behind the practice. This is an especially important problem with adolescents. To work out an efficient regulatory framework, we have to have an adequate picture on consumer behaviour and attitudes towards these products. Based on literature analysis of two focus group interviews, we have developed a motivational model on usage of DS, which has been tasted during a direct-question survey involving more than 500 respondents. Our results have proven that the consumption of DS is proliferated among young recreational athletes. One quarter of them consumes proteins, one tenth L-carnitine at least 2–3 times a week. The most important motivational factor is the improvement of sport performance. The level of confidence in these products is considerably influenced by peers and trainers. The propensity to underestimate the potentially adverse consequences of these products is high

Sample size and power calculations for open cohort longitudinal cluster randomized trials.

When calculating sample size or power for stepped wedge or other types of longitudinal cluster randomized trials, it is critical that the planned sampling structure be accurately specified. One common assumption is that participants will provide measurements in each trial period, that is, a closed cohort, and another is that each participant provides only one measurement during the course of the trial. However some studies have an "open cohort" sampling structure, where participants may provide measurements in variable numbers of periods. To date, sample size calculations for longitudinal cluster randomized trials have not accommodated open cohorts. Feldman and McKinlay (1994) provided some guidance, stating that the participant-level autocorrelation could be varied to account for the degree of overlap in different periods of the study, but did not indicate precisely how to do so. We present sample size and power formulas that allow for open cohorts and discuss the impact of the degree of "openness" on sample size and power. We consider designs where the number of participants in each cluster will be maintained throughout the trial, but individual participants may provide differing numbers of measurements. Our results are a unification of closed cohort and repeated cross-sectional sample results of Hooper et al (2016), and indicate precisely how participant autocorrelation of Feldman and McKinlay should be varied to account for an open cohort sampling structure. We discuss different types of open cohort sampling schemes and how open cohort sampling structure impacts on power in the presence of decaying within-cluster correlations and autoregressive participant-level errors

Effect of hair shearing on live performance and carcass traits of growing rabbits under hot ambient temperature

The aim of the study was to examine the effect of hair shearing in growing rabbits reared at high ambient temperature. The live performance and carcass traits of growing rabbits reared at 20°C (not sheared, C, n=50) or at 28°C (not sheared, H, n=50, or sheared at 5, 7 and 9 wk, HS, n=50) were compared. The ambient temperature and relative humidity were 20.5±1.1°C and 54±11% in the 20°C room and 28.8±0.2°C and 35±8% in 28°C room, respectively. Feed intake of H and HS groups decreased by 29.0 and 20.4%, respectively, compared to C rabbits (P<0.001). The same data for weight gain were 24.6 and 16.9% (P<0.001), and for body weight at 12 wk were 16.8 and 11.5% (P<0.001). At the same time, the feed conversion ratio improved (C: 3.53, HS: 3.34, H: 3.31; P<0.001). Nevertheless, the mortality rate of rabbits was not affected by the studied treatment and was overall low (0-4%). No differences were observed in dressing out percentages either (ratio of chilled carcass (CC) to the slaughter weight: 61.6-61.9%). The ratio of liver to CC differed among the experimental groups, with the highest value recorded in C group and the lowest in H group; HS rabbits showed intermediate results (C: 4.86%, HS: 4.27%, H: 3.91%; P<0.001). Lower ratios of fat deposits to reference carcass were also observed in rabbits kept at high ambient temperature (perirenal fat: C: 2.59%, HS: 1.82%, H: 1.60%; P<0.001; scapular fat: C: 0.89%, HS: 0.66%, H: 0.51%; P<0.001). It can be concluded that the negative effect of higher ambient temperature (28 vs. 20°C) on production in growing rabbits can be reduced significantly by hair shearing