The biomechanical and perceptual influence of chain resistance on the performance of the olympic clean

Proponents of chain training suggest that using chains hung from the ends of barbells rather than using conventional barbells alone enhances strength, power, and neuromuscular adaptations. The purpose of this study was to determine whether a conventional barbell with chains compared to a conventional barbell without chains would affect the performance of an Olympic Clean. The subjects were also asked regarding their perception of how chains affected their lifting. Four male and 3 female competitive weightlifters who used chains as part of their training participated in the study. The testing protocol compared the subjects' lifting 80% and 85% of their 1 repetition maximum (1RM) using conventional barbells and their lifting 80% and 85% of their 1RM using chains (75% conventional barbells + 5% chains and 80% conventional barbells + 5% chains, respectively). Video analysis evaluated the bar's vertical displacement and velocity and the rate of force production. Vertical ground reaction forces for the first-pull, unweighting, and second-pull phases of the lift were evaluated by using a force plate. After testing, the subjects completed a 2-item questionnaire asking individual perception of the effects of the chains. The results showed no significant difference for condition for any of the variables examined. In contrast, all subjects perceived that the chains required a greater effort. In conclusion, the results indicated that the addition of chains provided no greater value over lifting conventional barbells alone in the performance of the Olympic Clean, although the subjects perceived the chains to have a positive effect.     

The influence of aerodynamic and biomechanical factors on long jump performance

A new analysis, based on the equations of motion, is made of the influence of aerodynamic drag on the trajectory and aerial range achieved by a long jumper. The general result is applied to a particular case, namely the world long jump record obtained by Bob Beamon at the Mexico Olympics in 1968. Calculations are also made of the influence of body height and jumping technique on overall long-jump performance. A comparison is made between the relative importance of aerodynamic and anthropometric aspects of long jump performance.     

A preliminary investigation on time perception and autonomic self-regulation

This study sought to examine how perception of time duration was affected by two autonomic self-regulation treatment procedures: a biofeedback/self-regulation treatment program and a relaxation response treatment program. Time experience was assessed in two ways: time interval estimation during an actual treatment session (N=5, in each of the two groups) and subjective reporting (all 10 subjects in each group were evaluated). During an actual relaxation/self-regulation session, patients overestimated time duration and, retrospectively, patients in the group that learned to reduce blood pressure experienced time as slowing, whereas participants in the other treatment program experienced time as passing “normally” during the treatment sessions. All subjects reported that they usually experienced time as passing “normally” or corresponding to clock time. These results raise the question as to whether the experience of temporal slowing may be an important component of the psychological experience of the patients that allows autonomic learning to occur. Further research in this area is recommended and briefly discussed.     

A preliminary crystallographic investigation of avidin

Avidin was crystallized in various forms from 3m-ammonium sulphate or sodium phosphate at pH5.2. X-ray-crystallographic analysis of crystals from phosphate showed them to be orthorhombic, space group C222, containing two molecules per unit cell and with a single subunit as the asymmetric unit. The formation of the complex with biotin did not affect the morphology of the crystals.     

A preliminary investigation of the Nostoc punctiforme proteome

Nostoc punctiforme ATCC 29133 is a filamentous terrestrial cyanobacterium (prokaryote) that expresses several different phenotypes in response to environmental cues. When grown in nitrogen-deficient media the most abundant proteins in addition to phycobiliproteins were superoxide dismutase, ATP synthase, and peptidyl-prolyl cis-trans isomerases. A methylated peptide from an akinete marker protein was also identified, suggesting that methylation could potentially play a regulatory role through signaling. C-phycocyanin alpha-chain was methylated at the C-terminal end of the protein and tandem mass spectrometric data also identified peptides that were deamidated. Since a significant number of putative polyketide/non-ribosomal peptide synthase genes are present in the annotated genome, an analysis of a methanolic extract of whole cells was also performed, and a series of nostopeptolides were identified.     

A preliminary biomechanical study of cyclic preconditioning effects on canine cadaveric whole femurs

Biomechanical preconditioning of biological specimens by cyclic loading is routinely done presumably to stabilize properties prior to the main phase of a study. However, no prior studies have actually measured these effects for whole bone of any kind. The aim of this study, therefore, was to quantify these effects for whole bones. Fourteen matched pairs of fresh-frozen intact cadaveric canine femurs were sinusoidally loaded in 4-point bending from 50?N to 300?N at 1?Hz for 25 cycles. All femurs were tested in both anteroposterior (AP) and mediolateral (ML) bending planes. Bending stiffness (i.e., slope of the force-vs-displacement curve) and linearity R(2) (i.e., coefficient of determination) of each loading cycle were measured and compared statistically to determine the effect of limb side, cycle number, and bending plane. Stiffnesses rose from 809.7 to 867.7?N/mm (AP, left), 847.3 to 915.6?N/mm (AP, right), 829.2 to 892.5?N/mm (AP, combined), 538.7 to 580.4?N/mm (ML, left), 568.9 to 613.8?N/mm (ML, right), and 553.8 to 597.1?N/mm (ML, combined). Linearity R(2) rose from 0.96 to 0.99 (AP, left), 0.97 to 0.99 (AP, right), 0.96 to 0.99 (AP, combined), 0.95 to 0.98 (ML, left), 0.94 to 0.98 (ML, right), and 0.95 to 0.98 (ML, combined). Stiffness and linearity R(2) versus cycle number were well-described by exponential curves whose values leveled off, respectively, starting at 12 and 5 cycles. For stiffness, there were no statistical differences for left versus right femurs (p?=?0.166), but there were effects due to cycle number (p?相似文献   

中条山区蝶类考察初报

对山西中条山皇姑幔附近原始森林的蝶类进行了初步调查,获得７科６７种。该地区蝶类包括东洋区东份及古北区成份,其中主要种群为古北界区系成份,其地理分布区系属于华北区系,东洋区系则包括西南及华中成份,其侵入途径可能有两条：一是从秦岭山脉进入,二是从华中区,沿着山西、河北和河南三省交界地区进入中条山脉,由此表明山西东洋区系成份分界是中条山。     

白腐菌对木质素降解能力的测定

本文测定了7种霉菌对木质素的降解作用。结果表明,在测试的7种霉菌中,米曲霉(Aspergillus oryzal)2013、米曲霉2014、米曲霉2015和黑曲霉(Aspergillus niger)对木质素的降解能力较强,其降解率均达到90%以上。野外分离得到的细菌对木质素没有降解作用。     

福安三种不同茶园节肢动物群落的消长动态调查

根据对福建福安的3种不同茶园（天香有机茶园、北门高山茶园和溪柄平地茶园）的节肢动物群落消长动态调查。并经多样性分析,结果获知：福安3种茶园节肢动物群落的物种丰富度（s）和多样性指数（H）的大小顺序依次为：天香（S=19．64,H=2．537）〉北门（S=18．01,H=2．502）〉溪柄（S=17．59,H=2．297）;而均匀度指数的大小顺序是：北门（J=0．621）〉天香（J=0．595）〉溪柄（J=0．559）。表明植被比较丰富、人为干扰较少的茶园,节肢动物群落的物种丰富度、多样性指数和均匀度指数较高,害、益虫群落易于保持较好的平衡状态,有利于减少（或不使用）化学农药、发展绿色无公害茶叶生产。     

福安三种不同茶园节肢动物群落的消长动态调查

根据对福建福安的3种不同茶园(天香有机茶园、北门高山茶园和溪柄平地茶园)的节肢动物群落消长动态调查,并经多样性分析,结果获知:福安3种茶园节肢动物群落的物种丰富度(S)和多样性指数(H)的大小顺序依次为:天香(S=19.64,H=2.537)>北门(S=18.01,H=2.502)>溪柄(S=17.59,H=2.297);而均匀度指数的大小顺序是:北门(J=0.621)>天香(J=0.595)>溪柄(J=0.559).表明植被比较丰富、人为干扰较少的茶园,节肢动物群落的物种丰富度、多样性指数和均匀度指数较高,害、益虫群落易于保持较好的平衡状态,有利于减少(或不使用)化学农药、发展绿色无公害茶叶生产.     

意大利蝗越冬卵抗寒性初步研究

过冷却能力是昆虫越冬的主要策略之一。本研究测定了新疆乌鲁木齐2015年9月至次年5月意大利蝗卵过冷却点及土壤温度等指标的变化。结果显示,9月至次年3月, 80%以上的蝗卵过冷却点低于-24.0℃;4月和5月,蝗卵过冷却点显著上升至-22.7±0.7℃和-21.0±0.7℃,过冷却点在-23.9℃～-20.0℃的蝗卵比例分别达77.1%和52.1%。越冬过程中蝗卵含水量在土壤温度降至零下时短暂下降后迅速回升,并在越冬后的4月和5月剧烈上升。土壤温度(地下5 cm)较高且变化幅度不大,1月开始降至零下,2月达到最低。较高且稳定的土壤温度可能是意大利蝗卵维持较低过冷却点的原因,意大利蝗卵较强的抗寒能力是新疆草原蝗灾持续暴发的潜在原因。研究结果对开展新疆意大利蝗监测预警有很大意义。     

A preliminary investigation into the relationship between functional movement screen scores and athletic physical performance in female team sport athletes

There is little research investigating relationships between the Functional Movement Screen (FMS) and athletic performance in female athletes. This study analyzed the relationships between FMS (deep squat; hurdle step [HS]; in-line lunge [ILL]; shoulder mobility; active straight-leg raise [ASLR]; trunk stability push-up; rotary stability) scores, and performance tests (bilateral and unilateral sit-and-reach [flexibility]; 20-m sprint [linear speed]; 505 with turns from each leg; modified T-test with movement to left and right [change-of-direction speed]; bilateral and unilateral vertical and standing broad jumps; lateral jumps [leg power]). Nine healthy female recreational team sport athletes (age = 22.67 ± 5.12 years; height = 1.66 ± 0.05 m; body mass = 64.22 ± 4.44 kilograms) were screened in the FMS and completed the afore-mentioned tests. Percentage between-leg differences in unilateral sit-and-reach, 505 turns and the jumps, and difference between the T-test conditions, were also calculated. Spearman''s correlations (p ≤ 0.05) examined relationships between the FMS and performance tests. Stepwise multiple regressions (p ≤ 0.05) were conducted for the performance tests to determine FMS predictors. Unilateral sit-and-reach positive correlated with the left-leg ASLR (r = 0.704-0.725). However, higher-scoring HS, ILL, and ASLR related to poorer 505 and T-test performance (r = 0.722-0.829). A higher-scored left-leg ASLR related to a poorer unilateral vertical and standing broad jump, which were the only significant relationships for jump performance. Predictive data tended to confirm the correlations. The results suggest limitations in using the FMS to identify movement deficiencies that could negatively impact athletic performance in female team sport athletes.     

The influence of anti-(ricin toxin A chain) monoclonal antibodies on the pharmacokinetics of ricin toxin A chain and recombinant ricin A chain in mice

Summary Two monoclonal antibodies against ricin toxin A chain (RTA) have been examined for their effects on the blood survival and biodistribution of RTA and recombinant ricin A chain in mice. When admixed with the toxins at 1:1 molar ratios prior to intravenous injection, the antibodies prolonged blood survival and whole-body retention of both species of RTA, and this was due essentially to reduced renal clearance of the toxins. Immune complexes were identified by gel filtration chromatography and immune precipitation with anti-IgG antiserum in mixtures prior to injection and in the serum of mice injected with the mixtures. An irrelevant monoclonal antibody showed no complex formation, and no effect on biodistribution. These studies have shown that immune complexes formed between monoclonal antibodies and protein antigens of molecular mass up to at least 30 kDa survive in the circulation, rather than being cleared by the reticuloendothelial system. Such antibodies could be used to modulate the biodistribution of toxic molecules such as ribosome-inhibiting proteins like RTA. This might be exploited therapeutically, for example in the construction of bispecific antibodies against ribosomal inhibiting proteins and tumour-associated antigens.     

The influence of recovery duration after heavy resistance exercise on sprint cycling performance

ABSTRACT: Thatcher, R, Gifford, R, and Howatson, G. The influence of recovery duration after heavy resistance exercise on sprint cycling performance. J Strength Cond Res 26(11): 3089-3094, 2012-The aim of this study was to determine the optimal recovery duration after prior heavy resistance exercise (PHRE) when performing sprint cycling. On 5 occasions, separated by a minimum of 48 hours, 10 healthy male subjects (mean ± SD), age 25.5 ± 7.7 years, body mass 82.1 ± 9.0 kg, stature 182.6 ± 87 cm, deadlift 1-repetition maximum (1RM) 142 ± 19 kg performed a 30-second sprint cycling test. Each trial had either a 5-, 10-, 20-, or 30-minute recovery after a heavy resistance activity (5 deadlift repetitions at 85% 1RM) or a control trial with no PHRE in random order. Sprint cycling performance was assessed by peak power (PP), fatigue index, and mean power output over the first 5 seconds (MPO5), 10 seconds (MPO10), and 30 seconds (MPO30). One-way analysis of variance with repeated measures followed by paired t-tests with a Bonferroni adjustment was used to analyze data. Peak power, MPO5, and MPO10 were all significantly different during the 10-minute recovery trial to that of the control condition with values of 109, 112, and 109% of control, respectively; no difference was found for the MPO30 between trials. This study supports the use of PHRE as a strategy to improve short duration, up to, or around 10-second, sprint activity but not longer duration sprints, and a 10-minute recovery appears to be optimal to maximize performance.     

A biomechanical model of swallowing for understanding the influence of saliva and food bolus viscosity on flavor release

After swallowing a liquid or a semi-liquid food product, a thin film responsible for the dynamic profile of aroma release coats the pharyngeal mucosa. The objective of the present article was to understand and quantify physical mechanisms explaining pharyngeal mucosa coating. An elastohydrodynamic model of swallowing was developed for Newtonian liquids that focused on the most occluded region of the pharyngeal peristaltic wave. The model took lubrication by saliva film and mucosa deformability into account. Food bolus flow rate and generated load were predicted as functions of three dimensionless variables: the dimensionless saliva flow rate, the viscosity ratio between saliva and the food bolus, and the elasticity number. Considering physiological conditions, the results were applied to predict aroma release kinetics.Two sets of conditions were distinguished. The first one was obtained when the saliva film is thin, in which case food bolus viscosity has a strong impact on mucosa coating and on flavor release. More importantly, we demonstrated the existence of a second set of conditions. It was obtained when the saliva film is thick and the food bolus coating the mucosa is very diluted by saliva during the swallowing process and the impact of its viscosity on flavor release is weak. This last phenomenon explains physically in vivo observations for Newtonian food products found in the literature. Moreover, in this case, the predicted thickness of the mix of food bolus with saliva coating the mucosa is approximately of 20 μm; value in agreement with orders of magnitude found in the literature.     

Antimicrobial resistance and the food chain

The extent to which antibiotics given to animals contribute to the overall problem of antibiotic resistance in man is still uncertain. The development of resistance in some human pathogens, such as methicillin-resistant Staphylococcus aureus and multi-drug resistant Mycobacterium tuberculosis, is linked to the use of antimicrobials in man and there is no evidence for animal involvement. However, there are several good examples of transfer of resistant bacteria or bacterial resistance genes from animals to man via the food chain. A bacterial ecosystem exists with simple and complex routes of transfer of resistance genes between the bacterial populations; in addition to transfer of organisms from animals to man, there is also evidence of resistance genes spilling back from humans into the animal population. This is important because of the amplification that can occur in animal populations. The most important factor in the selection of resistant bacteria is generally agreed to be usage of antimicrobial agents and in general, there is a close association between the quantities of antimicrobials used and the rate of development of resistance. The use of antimicrobials is not restricted to animal husbandry but also occurs in horticulture (for example, aminoglycosides in apple growing) and in some other industrial processes such as oil production.