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1.
The aim of this study was to investigate the recovery process of a maximal stretch-shortening cycle (SSC) fatigue workout on the biomechanical performance of drop jump (DJ) and rebound jump (RBJ) on a force sledge apparatus. Thirteen elite level rugby players performed sledge DJs and RBJs before and 15, 45, 120, and 300 seconds after a maximum SSC fatigue workout. Flight time, ground contact time (CT), peak force, reactive strength index (RSI), and leg-spring stiffness were the dependent variables. The DJ results showed that after 15 seconds recovery, there was a significant reduction in flight time (FT) (p < 0.01), RSI (p < 0.001), peak force (p < 0.01), and leg stiffness (p < 0.001). Similarly, the results for the RBJ indicated that the fatigue workout significantly reduced FT (p < 0.001), peak force (p < 0.01), RSI (p < 0.01), and significantly increased CT (p < 0.05) at the 15-second interval. The results also indicated a potentiation effect at the 300-second interval because of significant increases in RSI, peak force, and leg stiffness (p < 0.05) for the RBJ and significant increases in RSI (p < 0.05), peak force, and leg stiffness (p < 0.01) and a significant decrease in ground CT (p < 0.05) for the DJ. A maximal SSC fatigue workout had both an inhibiting and potentiating effect on DJ and RBJ performance depending on the recovery interval. The efficiency of the SSC function was reduced immediately after the cessation of the fatigue workout. A potentiation effect was evident for both jumps 300 seconds postfatigue.  相似文献   

2.
The reliability of the reactive strength index (RSI) and time to stabilization (TTS) during maximal-effort plyometric depth jumps was examined. Twenty-two subjects performed three depth jumps from a height of 30 cm. Measures such as height of jump (JH), ground-contact time (CT), RSI, and TTS were obtained and analyzed for reliability using Cronbach alpha reliability coefficient and intraclass correlations. The JH, CT, and RSI were shown to be highly reliable from trial to trial (evidenced by high Cronbach reliability coefficients (alpha > 0.95) and high single- and average-measures intraclass correlations (>0.9). Time to stabilization was not reliable from trial to trial, as evidenced by a low Cronbach reliability coefficient (alpha < 0.7) and poor single- (<0.5) and average-measures (<0.7) intraclass correlations. The RSI was observed to be consistent for single measures, suggesting that coaches dealing with large numbers of athletes can conduct only a single trial from each depth jump height when attempting to optimize plyometric depth jump heights for their athletes. Time to stabilization could be a useful tool for strength and conditioning investigators to quantify the landing portion of plyometric exercises, but the protocol used in the current study to measure this variable did not prove to be reliable. Investigators wishing to use this measurement in such a context in future research studies may need to allow subjects appropriate habituation periods and control for arm movement during the landing phase of the exercise.  相似文献   

3.
The eccentric utilization ratio (EUR), which is the ratio of countermovement jump (CMJ) to static jump (SJ) performance, has been suggested as a useful indicator of power performance in athletes. The purpose of the study was to compare the EUR of athletes from a variety of different sports and during different phases of training. A total of 142 athletes from rugby union, Australian Rules Football, soccer, softball, and field hockey were tested. Subjects performed both CMJ and SJ on a force plate integrated with a position transducer. The EUR was measured as the ratio of CMJ to SJ for jump height and peak power. The rugby union, Australian Rules Football, and hockey athletes were tested during off-season and preseason to provide EUR data during different phases of training. For men, EUR for soccer, Australian Rules Football, and rugby was greater than softball (effect size range, 0.83-0.92). For women, EUR for soccer was greater than field hockey and softball (0.86- 1.0). There was a significant difference between the jump height and peak power method for the Australian Rules Football, rugby, and field hockey tests conducted preseason (p < 0.05). For field hockey, there was a significant increase in EUR from off-season to preseason. Athletes in sports such as soccer, rugby union, and Australian Rules Football appear to have higher EUR values, which reflects the greater reliance on stretch shortening activities in these sports. It does appear that EUR can be used to track changes in training with the values significantly increasing from off-season to preseason. The EUR provides the practitioner with information about the performance of athletes and appears to be sensitive to changes in the type of training being undertaken.  相似文献   

4.
Quantitative nuclear magnetic resonance (QMR) is being used in human adults to obtain measures of total body fat mass (FM) with high precision. The current study assessed a device specially designed to accommodate infants and children between 3 and 50 kg (EchoMRI-AH). Body composition of 113 infants and children (3.3-49.9 kg) was assessed using dual-energy X-ray absorptiometry (DXA), air displacement plethysmography (ADP, PeaPod for infants ≤ 8 kg and BodPod for children ≥ 6 years) and QMR. Results were compared with the deuterium oxide dilution technique (D(2)O) and a four-compartment model (4-C). The percentages of compliance were: 98% QMR; 75% DXA; 94% BodPod; and 95% PeaPod. Although QMR precision was high (coefficient of variation = 1.42%), it overestimated FM ~10% compared to the 4-C model and underestimated FM by ~4% compared to the deuterium method in children ≥ 6 years. QMR was less concordant with 4-C or D(2)O models for infants ≤ 8 kg. Thus, a piece-wise defined model for mathematically fitting the QMR data to the D(2)O data was employed and this adjustment improved the accuracy relative to D(2)O and 4-C for infants. Our results suggest that the pediatric QMR with appropriate mathematical adjustment provides a fast and precise method for assessing FM longitudinally in infants and in children weighing up to 50 kg.  相似文献   

5.

Background

Emotional intelligence (EI) can be broadly defined as the ability to cope with environmental demands. In the scientific research, however, there is not a univocal precise definition of EI and recent articles have underlined the necessity to explore its biological basis to advance understanding of the construct. The aim of study was to investigate if the antioxidant network may be associated with typical-performance or trait EI.

Methods

The study group consisted of 50 women (age, M = 25.10, SD = 3.87). Super Oxide Dismutase (SOD), Catalase (CAT), Glutathione Reductase (GR), and Glutathione Peroxidase (GPx) activities were evaluated on proteins extracted from Peripheral Blood Mononuclear Cells. Participants completed the Italian version of the EQ-i (Bar-On, 1997) as a measure of trait EI.

Results

We observed positive and significant correlations between some biological variables and EQ-i scores, and a significant predictive effect of CAT activity when controlling for related biological variables, age, and smoking.

Conclusions

Our preliminary study suggests that the antioxidant network may constitute some of trait EI''s biological basis. In particular, CAT and the SOD/CAT ratio could be two biological variables involved in some specific components of EI.  相似文献   

6.
Aim was to develop an in vivo technique which allows determination of femoro-tibial and of femoro-patellar 3D-kinematics in TKA simultaneously. The knees of 20 healthy volunteers and of eight patients with TKA (PCR, rotating platform) were investigated. Kinematics analysis was performed in an open MR-system at different flexion angles with external loads being applied. The TKA components were identified using a 3D-fitting technique, which allows an automated 3D-3D-registration of the TKA. Femoro-patellar and femoro-tibial 3D-kinematics were analyzed by image postprocessing. The validity of the postprocessing technique demonstrated a coefficient of determination of 0.98 for translation and of 0.97 for rotation. The reproducibility yielded a coefficient of variation (CV%) for patella kinematics between 0.17% (patello-femoral angle) and 6.8% (patella tilt). The femoro-tibial displacement also showed a high reproducibility with CV% of 4.0% for translation and of 7.1% for rotation. While in the healthy knees the typical screw-home mechanism was observed, a paradoxical anterior translation of the femur relative to the tibia combined with an external rotation occurred after TKA. Fifty percent of the TKA's experienced a condylar lift-off of >1mm predominately on the medial side. Regarding patellar kinematics significant changes were found in both planes in TKA with an increased patella height in the sagittal plane and patella tilt and shift in the transversal plane. The results demonstrate that the presented 3D MR-open based method is highly reproducible and valid for image acquisition and postprocessing and provides--for the first time--in vivo data of 3D-kinematics of the tibio-femoral and simultaneously of the patello-femoral joint during knee flexion.  相似文献   

7.
The heartbeat has been proposed as an intrinsic source of motion that can be used in combination with tagged Magnetic Resonance Imaging (MRI) to measure displacements induced in the liver as an index of liver stiffness. Optimizing a tagged MRI acquisition protocol in terms of sensitivity to these displacements, which are in the order of pixel size, is necessary to develop the method as a quantification tool for staging fibrosis. We reproduced a study of cardiac-induced strain in the liver at 3T and simulated tagged MR images with different grid tag patterns to evaluate the performance of the Harmonic Phase (HARP) image analysis method and its dependence on the parameters of tag spacing and grid angle. The Partial Volume Effect (PVE), T1 relaxation, and different levels of noise were taken into account. Four displacement fields of increasing intensity were created and applied to the tagged MR images of the liver. These fields simulated the deformation at different liver stiffnesses. An Error Index (EI) was calculated to evaluate the estimation accuracy for various parameter values. In the absence of noise, the estimation accuracy of the displacement fields increased as tag spacings decreased. EIs for each of the four displacement fields were lower at 0° and the local minima of the EI were found to correspond to multiples of pixel size. The accuracy of the estimation decreased for increasing levels of added noise; as the level increased, the improved estimation caused by decreasing the tag spacing tended to zero. The optimal tag spacing turned out to be a compromise between the smallest tag period that is a multiple of the pixel size and is achievable in a real acquisition and the tag spacing that guarantees an accurate liver displacement measure in the presence of realistic levels of noise.  相似文献   

8.
The purpose of this study was to compare and evaluate the performance of electronic leaf wetness duration (LWD) sensors in measuring LWD in a cotton crop canopy when unpainted and painted sensors were used. LWD was measured with flat, printed-circuit wetness sensors, and the data were divided into two periods of 24 days: from 18 December 2001 to 10 January 2002, when the sensors were unpainted, and from 20 January to 13 February 2002, when the sensors were painted with white latex paint (two coats of paint). The data analysis included evaluating the coefficient of variation (CV%) among the six sensors for each day, and the relationship between the measured LWD (mean for the six sensors) and the number of hours with dew point depression under 2 °C, used as an indicator of dew presence. The results showed that the painting markedly reduced the CV% values. For the unpainted sensors the CV% was on average 67% against 9% for painted sensors. For the days without rainfall this reduction was greater. Comparing the sensor measurements to another estimator of LWD, in this case the number of hours with dew point depression under 2 °C, it was also observed that painting improved not only the precision of the sensors but also their sensitivity, because it increases the ability of the sensor to detect and measure the wetness promoted by small water droplets.  相似文献   

9.
基于滨海盐土5个试验点的土壤含水量和室内土壤表面高光谱反射率,综合分析了350~2500 nm波段范围内土壤含水量与土壤光谱之间的关系,并基于比值光谱指数(RSI)、归一化光谱指数(NDSI)和差值光谱指数(DI)确定了光谱参数,进而构建土壤含水量估测定量模型.结果表明: 滨海盐土原始光谱反射率与土壤含水量呈显著负相关关系,且最大负相关出现在1930 nm(r=0.86)附近.对RSI、NDSI和DI的直线回归方程、幂函数回归方程进行对比,以RSI(R1407,R1459)为自变量构建的土壤含水量指数函数线性回归方程决定系数最大(0.780),标准误较小(0.016),拟合方程为y=0.00001e9.72053x.估测模型能够更好地监测滨海盐土土壤水分状况.基于RSI(R1407,R1459)构建的模型可实现对江苏省滨海盐土土壤水分的精确监测.  相似文献   

10.
The objective of this research is to examine the efficiency of EUR/USD market through the application of a trading system. The system uses a genetic algorithm based on technical analysis indicators such as Exponential Moving Average (EMA), Moving Average Convergence Divergence (MACD), Relative Strength Index (RSI) and Filter that gives buying and selling recommendations to investors. The algorithm optimizes the strategies by dynamically searching for parameters that improve profitability in the training period. The best sets of rules are then applied on the testing period. The results show inconsistency in finding a set of trading rules that performs well in both periods. Strategies that achieve very good returns in the training period show difficulty in returning positive results in the testing period, this being consistent with the efficient market hypothesis (EMH).  相似文献   

11.
用鲎试剂动态浊度法定量检测静脉注射用人免疫球蛋白中细菌内毒素含量并与家兔法检测热原的结果进行对比。根据《中华人民共和国》2005年版三部附录中的细菌内毒素动态浊度法制定内毒素限值,用ATi320-06型动态试管仪和该仪器配置的中文软件"生物探针-2002"分析检测结果。静脉注射用人免疫球蛋白经稀释消除了干扰因素,动态浊度法能定量检测出内毒素含量。实验满足2005年版中国药典要求:标准曲线相关系数的绝对值︱r︱≥0.980,回收率:50%≤R≤200%,变异系数符合鲎试剂厂家的建议值CV%10%。检测结果准确、灵敏、稳定、重现性好,与家兔法检测结果相一致。鲎试剂动态浊度法能定量检测静脉注射用人免疫球蛋白中细菌内毒素含量。  相似文献   

12.
The sexual compatibility between laboratory (LF) and wild (WF) strains of the Mexican fruit fly, Anastrepha ludens (Loew), was analyzed using analogous methodologies and experimental arenas under both laboratory and field conditions. Sexual compatibility was quantified with the following indices: the isolation index (ISI), male relative performance index (MRP), female relative performance index (FRPI), and the relative sterility index (RSI). ISI detected a certain level of incompatibility between strains under both laboratory and field conditions, because LF females tended to mate with LF males. LF mating performance was higher under laboratory than under field conditions. The relative performance indices for LF and the relative sterility index were higher in the laboratory than in the field. Differences between LF and WF in the times that males started calling and mating were observed in both environments. Importantly, WF males reduced their sexual activity under laboratory environments, whereas LF maintained similar activity levels in both conditions. The possible applications of the above-mentioned methods, not only to assess fly quality but also to determine the suitability of conditions in mass-rearing facilities, are discussed. Correlating laboratory quality to sexual behavior may contribute in the development of environmental parameters for mass-rearing facilities.  相似文献   

13.
ABSTRACT: Lloyd, RS, Oliver, JL, Hughes, MG, and Williams, CA. The effects of 4-weeks of plyometric training on reactive strength index and leg stiffness in male youths. J Strength Cond Res 26(10): 2812-2819, 2012-Although previous pediatric research has reported performance improvements in muscular power, agility, speed, and rate-of-force development after exposure to plyometric training, the effects on reactive strength index (RSI) and leg stiffness remain unclear. One hundred and twenty-nine boys from 3 different age groups (9, 12, and 15 years) participated and were divided into either an experimental (EXP) or control (CON) group within their respective age groups. The EXP groups followed a twice-weekly, 4-week plyometric training program, whereas the CON groups participated in their normal physical education lessons. Preintervention and postintervention measures were collected for RSI (during maximal hopping) and leg stiffness (during submaximal hopping). Both 12- and 15-year-old EXP groups made significant improvements in both absolute and relative leg stiffness (p < 0.05). The 9-year-old EXP group and CON groups for all ages did not make significant changes in leg stiffness. The 12-year-old EXP cohort also made significant improvements in RSI (p < 0.05). Both 15- and 9-year-old EXP cohorts, and CON groups for all ages, failed to show any significant improvements in RSI. The study concludes that improvements in RSI and leg stiffness after a 4-week plyometric training program are age dependent during childhood.  相似文献   

14.
The purpose of this study was to investigate the effects of 2 stretching protocols on stretch-shortening cycle performance in female Division I soccer players and female club rugby players. Fifteen soccer and rugby players (20.1 ± 5.9 years, 170.5 ± 14.2 cm, 70.4 ± 22.3 kg) participated in 3 test sessions with different treatments. The first treatment involved a warm-up of 10 minutes of exercise on a cycle ergometer (warm-up only [WO]), the second was this warm-up followed by static stretching (SS), and the third was this warm-up followed by dynamic stretching (DS). The treatments were administered randomly to negate an order effect. Each treatment was immediately followed by a reactive strength index (RSI) test requiring the athletes to drop off a box (45 cm in height) on to a force plate and upon landing immediately jump into the air while minimizing contact time (CT, milliseconds) and maximizing flight time (FT, milliseconds). The RSI was FT: CT. Repeated measures analysis of variance indicated that a significant treatment effect existed for RSI (F = 7.95, 2; p = 0.002) and FT (F = 7.43, 2; p = 0.003) but no significant effect for CT (F = 1.53, 2; p = 0.235). The RSI and FT were significantly greater in DS compared with that in SS and WO. Dynamic stretching is the preferred warm-up before an athletic event involving considerable jumping.  相似文献   

15.
Ecosystem services are an important nexus between people and nature. Nevertheless, their inclusion in place-based conservation and management is limited also because they are often intangible. The Ecological Infrastructure (EI) concept is a promising framework to address this, but a clear definition and mapping approach is still missing. We aim to analyse the uses of EI and to distil a definition and recommendations for using EI as a framework for mapping ecosystem services. A semi-systematic review of peer-reviewed and grey literature was conducted to examine: (1) perceptions of what constitutes EI (n = 117), and (2) EI mapping approaches (n = 51). The main interpretations of EI indicated that it should be natural or naturally functioning (56%); deliver multiple services (75%); and benefit humans (64%) and biodiversity (36%). EI was thus defined as ‘natural and naturally functioning ecological systems or networks of ecological systems that deliver multiple services to humans and enable biodiversity persistence’. Studies have used simple proxies, e.g., land cover, to identify EI, sometimes combined with service-specific variables. To evaluate EI performance (26% of studies), modelling all three ecosystem service aspects (capacity, flow, and demand) was considered appropriate. EI prioritisation (50% of studies) as part of a systematic spatial prioritisation process was recommended. Sixteen recommendations for mapping EI for inclusion in place-based conservation and management were developed. We illustrate how EI can be used to integrate ecosystem services into conservation and management in three real-world applications. The EI-based framework is a promising approach and supports the new ‘people and nature’ era in conservation.  相似文献   

16.
闽江河口湿地土壤全磷高光谱遥感估算   总被引:3,自引:1,他引:2  
章文龙  曾从盛  高灯州  陈晓艳  林伟 《生态学报》2015,35(24):8085-8093
磷是湿地生态系统必需和限制性元素,利用高光谱遥感数据对其进行估算对实现湿地土壤磷素快速和准确定量具有重要意义。选取闽江河口湿地作为研究区,于2013年5月,采集16个土壤剖面80个样本作为估算与验证模型样本;基于光谱指数建立土壤全磷(TP)含量估算模型,其中光谱指数包括原始光谱反射率(R)、比值土壤指数(RSI)、归一化土壤指数(NDSI)和有机质诊断指数(OII)。此外进一步分析反射光谱与不同形态磷,TP与有机质之间关系,以期初步揭示河口湿地土壤TP估算的机理。研究结果表明,闽江河口湿地土壤TP含量与R相关系数较高的区域分布在360-560 nm,并在406 nm处达到最大值-0.816;光谱指数RSI(R_(430),R_(830))、RSI(R_(460),R_(810))、RSI(R_(560),R_(580))、NDSI(R_(430),R_(830))、NDSI(R_(460),R_(830))、NDSI(R_(560),R_(580))和OII(R_(446))与土壤TP含量均有较高的相关系数,能较好的用于TP含量的估算;各估算模型决定系数(r~2)和均方根误差(RMSE)分别在0.657-0.805和0.052-0.067之间;验证模型r~2和RMSE分别在0.606-0.893和0.037-0.044之间。分潮滩建立TP含量估算模型是可行的,并且能提高部分光谱指数的估算精度。土壤TP含量的估算精度与磷素的组成有关,其中与铁吸附态磷关系较为密切,钙吸附态和铝吸附态磷关系较弱。土壤TP与有机质和氧化还原环境的存在密切关系可能是湿地土壤TP含量估算的重要机理。  相似文献   

17.
We developed a computationally efficient algorithm AMBIENCE, for identifying the informative variables involved in gene-gene (GGI) and gene-environment interactions (GEI) that are associated with disease phenotypes. The AMBIENCE algorithm uses a novel information theoretic metric called phenotype-associated information (PAI) to search for combinations of genetic variants and environmental variables associated with the disease phenotype. The PAI-based AMBIENCE algorithm effectively and efficiently detected GEI in simulated data sets of varying size and complexity, including the 10K simulated rheumatoid arthritis data set from Genetic Analysis Workshop 15. The method was also successfully used to detect GGI in a Crohn's disease data set. The performance of the AMBIENCE algorithm was compared to the multifactor dimensionality reduction (MDR), generalized MDR (GMDR), and pedigree disequilibrium test (PDT) methods. Furthermore, we assessed the computational speed of AMBIENCE for detecting GGI and GEI for data sets varying in size from 100 to 10(5) variables. Our results demonstrate that the AMBIENCE information theoretic algorithm is useful for analyzing a diverse range of epidemiologic data sets containing evidence for GGI and GEI.  相似文献   

18.
ResultsConjunctival EI was reproducible between images (average coefficient of variation 2.96%). EI of the palpebral conjunctiva correlated more strongly with haemoglobin concentration than that of the forniceal conjunctiva. Using the compact camera, palpebral conjunctival EI had a sensitivity of 93% and 57% and specificity of 78% and 83% for detection of anaemia (haemoglobin < 110 g/L) in training and internal validation sets, respectively. Similar results were found using the iPhone camera, though the EI cut-off value differed. Conjunctival EI analysis compared favourably with clinician assessment, with a higher positive likelihood ratio for prediction of anaemia.ConclusionsErythema index of the palpebral conjunctiva calculated from images taken with a compact camera or mobile phone correlates with haemoglobin and compares favourably to clinician assessment for prediction of anaemia. If confirmed in further series, this technique may be useful for the non-invasive screening for anaemia.  相似文献   

19.
The present study evaluates the groundwater quality for drinking and agricultural purposes and determines physicochemical characteristics of groundwater in the Sistan and Baluchistan province in Iran. In order to investigate the water quality, sampling was done in 654 open dug wells, the chemical parameters were analyzed, and water quality index was determined. In this regard, Langelier saturation index (LSI), Ryznar Stability index (RSI), Puckorius scaling index (PSI), Larson–Skold index (LS), and Aggressiveness index (AI) were considered to determine water suitability for industrial purposes. Finally, the analytical results were taken to generate the numerical spatial distribution of the parameters using the geographic information system (GIS) environment. According to the results, water sources were less corrosive based on AI and PSI, low and light corrosion according to RSI, and corrosion according to the Larsson–Sckold index. The results of the drinking water quality index showed that 1.2% shared extraction wells were classified as excellent, 52.1% as good, 39% as poor, 6% as very poor, and 1.7% as unsuitable for drinking purpose classes. In addition, irrigating water quality index illustrated that 19.9% and 80.1% wells were placed in the “excellent” and “Good” classes, respectively. Also, the quality of water in this study was categorized as brackish.  相似文献   

20.
The physiologic climate of Nigeria   总被引:1,自引:0,他引:1  
This study describes the spatial and temporal variations in the physiologic climate of Nigeria for 1951–2009 in terms of effective temperature (ET), temperature-humidity index (THI), relative strain index (RSI) and perception of 3,600 sampled populations. The main hypotheses are that (i) the existing vegetation-based ecological region could adequately elucidate the physiologic climate of the country, and (ii) physiologic stress has significantly increased over the years (1951–2009). Trends and changes in the selected indices (ET, THI and RSI) were examined over two time slices: 1951–1980 and 1981–2009. The results show that (1) the montane region was the most comfortable physiologic climate in Nigeria, and the regions around the Rivers Niger and Benue troughs were the most uncomfortable in most parts of the year, (2) physiologic stress in most parts of Nigeria has significantly increased in 1981–2009 over 1951–1980 (p?≤?0.05), (3) coping strategies to the uncomfortably hot and cold climate in Nigeria are limited to dressing mode, clothing materials and use of air conditioners or fan, (4) ET, THI and RSI results could be similar, and complementary; but each is with its strengths and weaknesses for annual or seasonal representations, which the others complemented for the interpretation of the physiologic climate of Nigeria. The study concluded that the relationship between the ecological classification of Nigeria and physiologic climate is rather complex, and the former could not elucidate the latter. The study cited inadequate meteorological data, especially on wind chill, and health records as limiting factors of studies on the Nigerian physiologic climates and the effect of extreme thermal conditions on the people.  相似文献   

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