The reliability of electromechanical delay and torque during isometric and concentric isokinetic contractions

The purpose of this investigation was to examine the intra-subject reliability of electromechanical delay (EMD) and torque of the dominant and non-dominant elbow flexors during isometric and isokinetic muscle contractions repeated over five consecutive days. Eleven volunteers that were unfamiliar with isokinetic dynamometry participated in this study and were asked to attend the laboratory on five consecutive days. An isokinetic dynamometer was used to exercise the elbow flexors under isometric, slow (60° s⁻¹) and fast (210° s⁻¹) isokinetic conditions; surface electromyography was recorded from the belly of biceps brachii and the signal was synchronised with the dynamometer to determine EMD. Intra-subject reliability for all measures was good (CV range, 3.1–6.5%) with no discernable difference between the dominant and non-dominant arms during isometric and isokinetic conditions. In addition, there was little difference in EMD and torque variability between the dominant and non-dominant arms which may have applications for clinicians and future research design when monitoring and investigating human muscle function. These data provide researchers and clinicians with an indication of the magnitude of change that is required to elucidate the presence of a meaningful change to muscle function in the elbow flexors.     

Effects of treadmill running on plasma beta-endorphin, corticotropin, and cortisol levels in male and female 10K runners

Reports of plasma beta-endorphin (B-EN) levels in response to submaximal exercise have been highly disparate. Variations in experimental design have complicated interpretation of previous research. The present study was designed to determine whether a sequential change in plasma beta-endorphin (B-EN), corticotropin (ACTH), and cortisol levels occurs in response to a 30-min submaximal run. Twenty-three subjects were divided into four groups: male runners, female runners, sedentary males and sedentary females. Subjects ran on a treadmill at 80% of previously determined maximum heart rate. Five plasma samples were obtained through an indwelling catheter before exercise (-30 and 0 min), at 15 and 30 min of exercise, and after 30 minutes of recovery. The run resulted in no rise in B-EN, ACTH, and cortisol despite an elevated rectal temperature. B-EN values were significantly higher in males than in females (p less than 0.01). No sex or training differences were seen with respect to change of hormone concentrations over the course of the run. Three male runners developed symptoms of vasovagal syncope after the catheter placement and had high initial B-EN, ACTH, and cortisol concentrations which decreased throughout the run. These data indicate that gender and training do not affect ACTH and cortisol concentrations before, during, and after 30 min of treadmill running at 80% of maximum heart rate, whereas B-EN concentrations are higher in males under these conditions.     

Effects of order of presentation of exercise intensities and of sauna baths on perceived exertion during treadmill running

Thirteen male subjects performed a running test on the treadmill consisting of four standard exercise intensities [65%, 75%, 85%, 95% maximal O2 uptake (VO2 max)] presented in ascending, descending or random order. At the end of each exercise intensity, O2 consumption, heart rate (fc), venous blood lactate concentration [( Ia]b) and perceived exertion were assessed. This last variable was determined according to the Borg nonlinear CR-20 scale. The same variables were also determined during exercise at a standard intensity (65% or 95% VO2 max) performed before and after a Finnish sauna bath. Ratings of perceived exertion showed a good test-retest reliability (r = 0.77); they were the same when the exercise intensity was expressed in relative (%VO2 max) or absolute (speed) terms, and were independent of the order of presentation of the exercise. The latter had no effect on fc either but it did, however, influence [Ia]b, which was significantly higher in the descending, as compared to the ascending or random modes of presentation. The sauna bath increased fc at a given exercise intensity, but left perceived exertion and [Ia]b unchanged. It was concluded that at least under the present experimental conditions, fc and venous [Ia]b do not play a major role as determinants of perceived exertion.     

Agreement between spatiotemporal parameters from a photoelectric system with different filter settings and high-speed video analysis during running on a treadmill at comfortable velocity

The aim of this study was to determine the level of agreement between spatiotemporal gait characteristics from a photoelectric system with different filter settings and high-speed video analysis during running on a treadmill at comfortable velocity. Forty-nine runners performed a running protocol on a treadmill at comfortable velocity. Two systems were used to determine spatiotemporal parameters (i.e. contact time [CT], flight time [FT], step frequency [SF] and step length [SL]) during running: OptoGait system and high-speed video analysis at 1000 Hz. The collected data was re-filtered in the OptoGait software by using nine different settings (i.e. 0_0, 1_1, 2_2, 3_3, 3_4, 4_4, 4_5, 5_4 and 5_5), and compared to those obtained through video analysis. The Pearson correlation analysis revealed very large correlations (r > 0.9, p < 0.001) in CT, FT, SF and SL between both systems, regardless of the OptoGait’s filter settings. The ICC reported an almost perfect association (ICC > 0.9) for both SL and SF regardless of the filter setting. However, large variations between filter settings according to the data from video analysis were reported in CT and FT (0_0, 1_1 and 2_2 filter settings obtained an association ICC > 0.9, whereas other filters obtained lower ICCs). Bland-Altman plots revealed small bias and error and no presence of heteroscedasticity of error for 1_1 setting. In conclusion, the filter setting for the OptoGait system should be considered to minimize the bias and error of spatiotemporal parameters measurement. For running on a treadmill, the 1_1 filter setting is recommended if gait parameters are to be compared to a high-speed video analysis (1000 Hz).     

Tutorial. Surface EMG detection,conditioning and pre-processing: Best practices

This tutorial is aimed primarily to non-engineers, using or planning to use surface electromyography (sEMG) as an assessment tool for muscle evaluation in the prevention, monitoring, assessment and rehabilitation fields. The main purpose is to explain basic concepts related to: (a) signal detection (electrodes, electrode–skin interface, noise, ECG and power line interference), (b) basic signal properties, such as amplitude and bandwidth, (c) parameters of the front-end amplifier (input impedance, noise, CMRR, bandwidth, etc.), (d) techniques for interference and artifact reduction, (e) signal filtering, (f) sampling and (g) A/D conversion, These concepts are addressed and discussed, with examples.The second purpose is to outline best practices and provide general guidelines for proper signal detection, conditioning and A/D conversion, aimed to clinical operators and biomedical engineers. Issues related to the sEMG origin and to electrode size, interelectrode distance and location, have been discussed in a previous tutorial. Issues related to signal processing for information extraction will be discussed in a subsequent tutorial.     

Surface EMG amplitude and frequency dependence on exerted force for the upper trapezius muscle: a comparison between right and left sides

Surface electromyographic (EMG) amplitude and mean power frequency (MPF) were used to study the isometric muscular activity of the right versus the left upper trapezius muscles in 14 healthy right-handed women. The EMG activity was recorded simultaneously with force signals during a 10-15 s gradually increasing exertion of force, up to maximal force. Only one side at a time was tested. On both sides there was a significant increase in EMG amplitude (microV) during the gradually increasing force from 0% to 100% maximal voluntary contraction (MVC). The right trapezius muscle showed significantly less steep slopes for regression of EMG amplitude versus force at low force levels (0%-40% MVC) compared intra-individually with high force levels (60%-100% MVC). This was not found for the left trapezius muscle. At 40% MVC a significantly lower MPF value was found for the right trapezius muscle intra-individually compared with the left. An increase in MPF between 5% and 40% MVC was statistically significant when both sides were included in the test. The differences in EMG activity between the two sides at low force levels could be due to more slow-twitch (type I fibres) motor unit activity in the right trapezius muscles. It is suggested that this is related to right-handed activity.     

The acute effects of local muscle vibration frequency on peak torque,rate of torque development,and EMG activity

PurposeVibratory stimuli enhance muscle activity and may be used for rehabilitation and performance enhancement. Efficacy of vibration varies with the frequency of stimulation, but the optimal frequency is unclear. The purpose of this study was to examine the effects of 30 Hz and 60 Hz local muscle vibration (LMV) on quadriceps function.MethodsTwenty healthy volunteers (age = 20.4 ± 1.4 years, mass = 68.1 ± 11.0 kg, height = 170.1 ± 8.8 cm, males = 9) participated. Isometric knee extensor peak torque (PT), rate of torque development (RTD), and electromyography (EMG) of the quadriceps were assessed followed by one of the three LMV treatments (30 Hz, 60 Hz, control) applied under voluntary contraction, and again immediately, 5, 15, and 30 min post-treatment in three counterbalanced sessions. Dependent variables were analyzed using condition by time repeated-measures ANOVA.ResultsThe condition × time interaction was significant for EMG amplitude (p = 0.001), but not for PT (p = 0.324) or RTD (p = 0.425). The increase in EMG amplitude following 30 Hz LMV was significantly greater than 60 Hz LMV and control.ConclusionsThese findings suggest that 30 Hz LMV may elicit an improvement in quadriceps activation and could be used to treat quadriceps dysfunction resulting from knee pathologies.     

Measuring mast seeding behavior: relationships among population variation,individual variation and synchrony

Mast seeding, or masting, is the variable production of flowers, seeds, or fruit across years more or less synchronously by individuals within a population. A critical issue is the extent to which temporal variation in seed production over a collection of individuals can be viewed as arising from a combination of individual variation and synchrony among individuals. Studies of masting typically quantify such variation in terms of the coefficient of variation (CV). In this paper we examine mathematically how the population CV relates to the mean individual CV and synchrony, concluding that the relationship is a complex one which cannot isolate an overall measure of synchrony, and involves additional factors, principally the number of plants sampled and the mean productivity per plant. Our development suggests some simple approximate relationships of population CV to individual variability, synchrony and the number of individuals. These were found to fit quite well when applied to data from 59 studies which included seed production at the individual level.     

Covariation between mean vole density and variability drives the numerical response of storks to vole prey

Hušek et al. (Popul Ecol 55:363–375, 2013 ) showed that the numerical response of storks to vole prey was stronger in regions where variability in vole density was higher. This finding is, at first sight, in contradiction with the predictions of life-history theory in stochastic environments. Since the stork productivity-vole density relationship is concave, theory predicts a negative association between the temporal variability in vole density and stork productivity. Here, we illustrate this negative effect of vole variability on stork productivity with a simple mathematical model relating expected stork productivity to vole dynamics. When comparing model simulations to the observed mean density and variability of thirteen Czech and Polish vole populations, we find that the observed positive effect of vole variability on stork numerical response is most likely due to an unusual positive correlation between mean and variability of vole density.     

山茱萸种质资源数量性状评价及相关性分析

对从全国收集的75份山茱萸种质资源,从叶长、叶宽、果实横径、果实纵径、鲜果百粒重、种子千粒重、种子含水量、枣皮灰分、枣皮水分、水溶性浸出物和马钱素含量等表型性状,分析其变异系数和各性状间的相关性.分析结果显示,75份山茱萸种质资源在叶长、叶宽、鲜果百粒重、种子千粒重、枣皮灰分和马钱素含量等性状上的变异系数均高于10％,说明这些性状变化范围较大,个体间性状不稳定,易受环境因素的影响;而果实横径、果实纵径、种子含水量、枣皮水分和水溶性浸出物的变异系数均低于10％,说明这些性状变异较小,表型性状比较稳定.相关性分析结果显示,各性状间都存在一定的相关性,其中果实纵径和果实横径与鲜果百粒重呈显著正相关(0.396和0.312,P ＜0.01),说明果实纵横径是影响果实重量的关键因素;水溶性浸出物大小与果实横径(0.481,P＜0.01)、果实纵径(0.280,P＜0.05)、马钱素含量(0.372,P＜0.01)呈现显著性正相关,表明水溶性浸出物含量的高低与山茱芰有效成分马钱素含量和果实大小及形状密切正相关,这将为种质的筛选、评价和新品种选育提供依据.     

Phosphorus effect on the uptake,translocation and accumulation of the14C-urea in orchard grass (Dactylis glomerata L.)

Summary The effect of different phosphorus supplies on the uptake, translocation and accumulation of¹⁴C-urea by orchard grass was investigated. Phosphorus starvation inhibits the uptake, translocation and accumulation of the carbon of urea similarly to the nitrogen of urea. As compared with the uptake process the reduction of the accumulation is much more effected by the inhibition of the carbon translocation from roots to the aboveground parts. Lack of phosphorus also decreases the incorporation of the¹⁴C of urea into high-molecular compounds. The effect of phosphorus deficit on the accumulation of¹⁴C-urea increases with time of starvation.     

A study on variability of quantitative sensory testing in healthy participants and painful temporomandibular disorder patients

Objectives: Quantitative sensory testing has mainly used thresholds to evaluate somatosensory sensitivity so far. The variability of different measures from session to session has also been investigated, but the variability of the single individual measures of a threshold or subject-based reports has not been considered. This study aimed to investigate the potential value of threshold variability in one session as a measure of internal consistency in somatosensory function.

Methods: The standardized quantitative sensory testing battery developed by the German Research Network on Neuropathic Pain was performed bilaterally over the infraorbital, mental, and hand regions in 70 healthy and 22 temporomandibular disorder pain participants. Somatosensory variability was investigated by calculating the Coefficient of Variation of three to five repeated measures in one threshold determination. The influences of side, gender, site, age, and presence of pain on the somatosensory variability were evaluated.

Results: In the healthy participants, somatosensory variability was region dependent: hand?>?mental and/or infraorbital for CDT, WDT, HPT, MDT-N, MPT-Y, MPT-N, WUR, and MPS (p?≤?0.043), infraorbital?>?hand for VDT (p?=?0.001), mental?>?infraorbital for HPT and WUR (p?≤?0.001); and age dependent for WDT, TSL, CPT, HPT, MDT-Y, MDT-N, MPT-N, and WUR (p?≤?0.017). Gender and side had no main effect on variability (p?≥?0.136). The pain patients presented higher variability compared with healthy participants for TSL, MDT-N, MPT-Y, WUR, and PPT (p?≤?0.033).

Discussion: The somatosensory variability along with the threshold would be a more complete method to investigate the somatosensory disorders and underlying pain mechanisms. The correlation between pain duration and somatosensory variability should be studied further with different pain conditions.     

The effect of hyperthermia on cell viability,oxidative damage,and heat shock protein expression in hepatic cells of grass carp (Ctenopharyngodon idellus)

The purpose of the study was to investigate the effects of mild hyperthermia on cell viability, release of lactate dehydrogenase (LDH), superoxide dismutase (SOD) activity, malondialdehyde (MDA) formation, total antioxidant capacity (T-AOC), and the relative mRNA levels of heat shock protein (HSP60, 70, and 90) in hepatic cells of grass carp (Ctenopharyngodon idellus) before and after temperature stress. Cultured cells were exposed to thermal stress (32 °C) for 0.5, 1, 2, 4, and 8 h. The results showed that hyperthermia stress significantly reduced cell viability (P<0.01) and increased LDH release at 0.5 and 1 h (P<0.05). Additionally, hyperthermia stress led to oxidative stress as evidenced by significantly decreased T-AOC after treating cells for 0.5 and 8 h (P<0.05). SOD activity also significantly decreased after 1 h of stress (P<0.05), but MDA formation increased after 8 h of stress (P<0.05). This may be partly responsible for the lower cell viability and higher LDH release we observed. The differences between SOD activity, MDA formation, and T-AOC between the 2 h treatment group and the control were smaller than that of other groups. This indicated that cellular antioxidant enzyme systems play an important role in the defense against oxidative stress. Further tests showed that the expression of HSP60 at 1, 2, and 4 h (P<0.05), HSP70 at 0.5 and 1 h (P<0.01), and HSP90 at all time points after stress were higher (P<0.01) than pre-stress levels. This suggested that HSPs possess the ability to modulate cellular anti-stress responses and play key roles in protecting organisms from heat stress. In conclusion, hyperthermia inhibits cell proliferation, induces cell oxidative stress, and enhances HSP expression in hepatic cells of grass carp.     

Patterns of morphometric variation in birds' tails: length, shape and variability

In Palaearctic birds, tail length was more variable than wing and tarsus, but not bill lengths. Tails of the ornamental shapes pin, lyre and graduated varied more in length than did non-ornamental shapes. Log coefficient of variation (C V) tail length showed an overall U-shaped relationship with longtailedness, but although the CV for most tail shapes increased in short-tailed species, only in ornamental shapes was C V also high in long-tailed species. C V of fork depth was lowest at a fork depth of 2, and considerably higher in shallow forked tails. CV streamer lengths were similar to CV deep fork depths. The more deeply forked tails thus seem ornamental. Phylogenetically independent contrasts confirmed in males, but not females, that long-tailed species had greater CV than medium-tailed species, and the greater CV of graduated than square tails, but the CV of short- and medium-tailed species did not differ. These comparisons, however, did not control for tail shape. The greater elongation and CV of tails with ornamental shapes are consistent with an influence of sexual/signal selection on these tails, and the increase in CV with longtailedness suggests that Weber's law applies to the perceptual threshold for tail length. Sexual selection may have a widespread, but moderate, influence on tail traits in birds.     

我国红壤区土壤钼、硼、硒元素特征及其对牧草生长影响研究进展

实行肥料科学配施与红壤培肥管理是山区草业发展的重要技术环节．我国南方红壤区土壤普遍存在着硼、钼、硒元素缺乏现象,合理施用钼、硼、硒微量元素肥料对豆科与禾本科牧草的植株生长以及提高产草量和种子产量有明显的促进作用．文中概述了我国红壤区土壤中钼、硼、硒元素的存在形态、化学特征、内在变化、可给性及含量状况,探讨了施用3种微量元素肥料对牧草生长过程有效养分吸收与累积的影响及其相应生理功能,综述了牧草植物缺乏钼、硼、硒元素的特征症状、诊断方法及其矫治措施．     

脆化草鱼(Ctenopharyngodon idellus C.et V)的病理生理生态学

分别就形态、生态和病理学性状对处于脆化终极阶段（LD50≥6．67kg／kgbw）的草鱼与普通草鱼进行比较分析。高度脆化的草鱼在生态学上出现明显变化,体长和体重的指数方程W=al^n显著不同于普通草鱼,DO阈值由平均值O．54mg／L上升到平均值1．68mg／L,CO2麻醉浓度（呼吸抑制值）由194mg／L高浓度下降到52．42～65．36mg／L,Root效应及Broh效应显著改变。解剖分析表明,草鱼脆化过程是渐进性组织病变的生理过程,包括各系统器官的功能性病变,最终使过度脆化的草鱼由于血液循环障碍直接导致死亡。草鱼脆化死亡具有明显的饲料（蚕豆）累积剂量——效应反应的毒理学规律,脆化草鱼的体长与体重的指数方程W=18．1719L^2.4360可作为华南地区商品脆肉鲩标准的参考。研究结果将为脆化草鱼规模化集约养殖和提高脆化草鱼长途运输成活率提供参考。     

Influence of flower functionality and pollination system on the pollen size-pistil length relationship

Twenty-five biotically pollinated plants of the Chaco Serrano Forest (Córdoba, Argentina) were studied in order to analyze whether ‘flower functionality’ is related to the relationship between pollen size and pistil length. Because flower functionality may act on the respective mean values of pollen size and pistil length rather than on intraspecific variation in these traits, we expected (1) a high positive correlation between pollen size and pistil length in a set of sympatric species, independent of their degree of pollination specialization or generalization; and (2) no interspecific correlation between the coefficients of variation (CVs) of those traits. On the other hand, on the assumption that pollinators are influencing the variation in floral traits (e.g. in pistil length) we expected lower mean phenotypic variation of pollen size and pistil length in pollination-specialist plants than in pollination-generalist ones. A positive correlation between pollen size and pistil length was found for the set of species, but not between the CVs of these traits. This trend was maintained when pollination-specialist plants were analyzed separately, but no statistical significance was obtained for the correlation in pollination-generalist plants. Contrary to our expectations, pollination-specialist plants did not show less mean intraspecific variation in floral traits than pollination-generalist plants. Therefore, the relationship between pollen size and pistil length among species suggests that the pollination system may be of less importance as a selective force than flower functionality.     

Morphology and taxonomic status of the grass snake, Natrix natrix (L.) (Reptilia, Squamata, Colubridae) on the island of Gotland, Sweden

The isolated population of grass snakes, Natrix natrix (L.), on the island of Gotland in die Baltic Sea is described and illustrated. Comparisons are made with the surrounding mainland grass snake. On the basis of morphological and ecological divergence, the conclusion is drawn that the Gotland population represents a new subspecies.     

F-81 skeleton from Wadi Mataha, Jordan, and its bearing on human variability in the Epipaleolithic of the Levant

The discovery of a Middle Epipaleolithic adult skeleton (F-81) at the site of Wadi Mataha in southern Jordan provides new insights into human variability in the Epipaleolithic of the Levant. This paper analyzes the skeletal morphology of Wadi Mataha F-81 in the context of other Epipaleolithic remains from Jordan and Israel to assess the current evidence for morphological variability throughout this period. The F-81 skeleton shares morphological features with earlier Epipaleolithic skeletons from Ohalo and Nahal Ein Gev, and later Natufian populations. Despite the morphological similarities, F-81 extends the range of known variability prior to the Natufian with its unusually small stature and unique combination of morphological characteristics. High levels of cranial and postcranial robusticity suggest that the F-81 individual was physically active and terrestrially mobile. Pronounced bilateral asymmetry in the upper limb suggests significant lateralization of habitual activity. In the context of Epipaleolithic remains, the F-81 skeleton provides preliminary evidence for greater morphological variability, terrestrial mobility, and lateralized habitual behavior prior to the Natufian, and skeletal gracilization between the Middle and Late Epipaleolithic in the Levant.     

The influence of Acacia tortilis (Forssk.) Subsp. raddiana (Savi) and livestock grazing on grass species composition, yield and soil nutrients in arid environments of South Tunisia

The objectives of the study, conducted during the 2003/2004 growing season in the National Park of Bou Hedma (South Tunisia), were to quantify the effects of the single-woody species Acacia tortilis subsp. raddiana on grass species composition, on total plant cover, on density of perennial species, on dry matter (DM) yield and on soil nutrients at lightly and heavily grazed sites. In each study site, two subhabitats were distinguished, i.e. under tree canopies and open grasslands. In the lightly grazed site, the nutrient status of soil (organic matter, total N, extractable P, K⁺, Ca²⁺, Na⁺, Mg²⁺) under Acacia raddiana canopy, was found to be significantly higher (p<0.05) than under the open grassland. In the same way, total plant cover (p<0.05), density of perennial species (p<0.01) and DM yield (p<0.01) were significantly higher under tree canopies in the lightly grazed site. Heavy grazing proved to exert a strong overriding effect over the positive influences of the woody plants. For most studied parameters, a non-significant difference was recorded between canopied and uncanopied subhabitats. Some palatable species were frequently found under trees. In the heavily grazed site, these species are being replaced by less desirable species. This emphasizes the importance of conservation stocking rates and proper pasture management.