A hierarchical model for spatially clustered disease rates

Maps of regional disease rates are potentially useful tools in examining spatial patterns of disease and for identifying clusters. Bayes and empirical Bayes approaches to this problem have proven useful in smoothing crude maps of disease rates. In recent years, models including both spatially correlated random effects and spatially unstructured random effects have been very popular. The spatially correlated random effects have been proposed in an attempt to capture a general clustering in the data. As an alternative, we propose replacing the spatially structured random effect with fixed clustering effects associated with particular areas. A reversible jump Markov chain Monte Carlo (RJMCMC) algorithm for posterior inference is described. We illustrate the model using the well-known New York leukaemia data.     

ℋ︁∞ control of discrete‐time Markov jump systems with bounded transition probabilities

This paper deals with the class of discrete‐time linear systems with random abrupt changes and unknown transition probabilities but varying between known bounds for each mode. The ℋ︁_∞ control problem of this class of systems is revisited and new sufficient conditions are developed in the linear matrix inequality (LMI) setting to design the state‐feedback controller that stochastically stabilizes the system under consideration and at the same time guarantees the disturbance rejection with a desired level γ . Sufficient conditions for existence of the state‐feedback controller are developed. It is shown that the addressed problem can be solved if the corresponding developed LMIs are feasible. Numerical examples are employed to show the usefulness of the proposed results. Copyright © 2008 John Wiley & Sons, Ltd.     

Effects of differing intensities of static stretching on jump performance

Acute bouts of static stretching have been shown to impair performance. Most published studies have incorporated static stretching that stressed the muscle(s) to the point of discomfort (POD). There are very few studies that have examined the effects of submaximal intensity (less than POD) static stretching on subsequent performance. Ten participants were pre-tested by performing two repetitions of three different stretches to assess range of motion (ROM) and two repetitions each of five different types of jumps. Following pre-testing, participants were stretched four times for 30 s each with 30 s recovery for the quadriceps, hamstrings and plantar flexors at 100% (POD), 75% and 50% of POD or a control condition. Five minutes following the stretch or control conditions, they were tested post-stretch with the same stretches and jumps as the pre-test. All three stretching intensities adversely affected jump heights. With data collapsed over stretching intensities, there were significant decreases in jump height of 4.6% (P = 0.01), 5.7% (P < 0.0001), 5.4% (P = 0.002), 3.8% (P = 0.009) and 3.6% (P = 0.008) for the drop jump, squat jump, countermovement jump (CMJ) to a knee flexion of 70°, CMJ using a preferred jump strategy and short amplitude CMJ respectively. An acute bout of maximal or submaximal intensity stretching can impair a variety of jumping styles and based on previous research, it is hypothesized that changes in muscle compliance may play a role.     

Comparison of conventional resistance training and the fly-wheel ergometer for training the quadriceps muscle group in patients with unilateral knee injury

A fly-wheel ergometer (FWE) offering resistance training of the knee extensors has been designed for space travel and found to be effective during bed rest. The possibility exists that this device is also effective in training the knee extensors after knee injury. The purpose of this study was to compare the FWE to standard knee extensor training equipment for their effects on individuals with a history of knee injury, a group who commonly suffer from weakness of the knee extensors that effects their function. Twenty-nine subjects completed the study, which included tests of knee self-assessment, knee extensor static and dynamic muscle strength, size and neural activation as well as single leg power output, standing balance and vertical jump performance. Both groups showed statistically significant (P < 0.05) improvements in these variables over the 3-month training period but no differences were noted between the groups. The FWE appears to be as effective as standard resistance training equipment for improving knee extensor muscle group size and performance after knee injury.     

Mechanical efficiency during repetitive vertical jumping

The purpose of this study was to compare mechanical efficiency between repeated static jumps (SJ), countermovement jumps (CMJ), drop jumps from 75% of maximum CMJ jump height (75DJ) and drop jumps from 125% of maximum CMJ height (125DJ). Subjects included eight jump-trained males. All subjects completed 30 continuous repetitions in the SJ, CMJ, 75DJ, and 125DJ. Oxygen consumption, peak force and center of mass displacement for each repetition during the four jumping patterns were measured. ME was calculated from a combination of force-time curves, displacement-time curves and lactate-corrected oxygen consumption values. In addition, muscle activity was recorded from the vastus medialis, vastus lateralis and biceps femoris using surface electromyography (EMG). 125DJ and 75DJ resulted in significantly (P ≤ 0.05) greater ME in comparison to CMJ and SJ. CMJ resulted in significantly greater ME in comparison to SJ. In addition, braking phase muscle activity was significantly greater in 125DJ and 75DJ in comparison to CMJ. Negative work was significantly different between 125DJ, 75DJ and CMJ (125DJ > 75DJ > CMJ). There was a significant positive correlation (r = 0.68) between ME and negative work performed across 125DJ, 75DJ and CMJ. These findings suggest that stretch-shortening cycle movements, which include a strenuous braking phase combined with simultaneous high muscle activity, increase ME. This may be due to optimal muscle-tendon unit kinetics and usage of stored elastic energy.     

Incorporating covariates in mapping heterogeneous traits: a hierarchical model using empirical Bayes estimation

Complex genetic traits are inherently heterogeneous, i.e., they may be caused by different genes, or non-genetic factors, in different individuals. So, for mapping genes responsible for these diseases using linkage analysis, heterogeneity must be accounted for in the model. Heterogeneity across different families can be modeled using a mixture distribution by letting each family have its own heterogeneity parameter denoting the probability that its disease-causing gene is linked to the marker map under consideration. A substantial gain in power is expected if covariates that can discriminate between the families of linked and unlinked types are incorporated in this modeling framework. To this end, we propose a hierarchical Bayesian model, in which the families are grouped according to various (categorized) levels of covariate(s). The heterogeneity parameters of families within each group are assigned a common prior, whose parameters are further assigned hyper-priors. The hyper-parameters are obtained by utilizing the empirical Bayes estimates. We also address related issues such as evaluating whether the covariate(s) under consideration are informative and grouping of families. We compare the proposed approach with one that does not utilize covariates and show that our approach leads to considerable gains in power to detect linkage and in precision of interval estimates through various simulation scenarios. An application to the asthma datasets of Genetic Analysis Workshop 12 also illustrates this gain in a real data analysis. Additionally, we compare the performances of microsatellite markers and single nucleotide polymorphisms for our approach and find that the latter clearly outperforms the former.     

用量子波的频率改变人的内分泌和外分泌及神经系统

此报告是量子波的频率作用于人体的实验结果分析。以心跳的可控为例分析求证是量子波的作用。量子波的频率透射人体势垒,其能量能够引起量子跃迁事件的发生,使得组成人的原子、分子的电子结构发生变化,人体内的酶、糖、蛋白质、脂肪等生物大分子相应发生变化,从内分泌到外分泌再到神经系统等可以向事先计划的方面变化。通过改变势垒而改变波的频率并且利用这个频率提供的能引导改变人是很现实的事。     

Kinetics of Demixing and Remixing Transitions in Aqueous Solutions of Poly(N‐isopropylacrylamide): A Temperature‐Jump 1H NMR Study

Summary: The time course of the coil‐to‐globule collapse and intermolecular aggregation of poly(N‐isopropylacrylamide) in aqueous solution upon exceeding the lower critical solution temperature (LCST) are investigated by temperature‐jump ¹H NMR spectroscopy. After the temperature jump, we record the time dependences of (i) the mobile fraction of the polymer chain as revealed by the intensity of the liquid‐like NMR signal, (ii) the local mobility of those chains as revealed by the transverse relaxation time T₂, and (iii) their self‐diffusion coefficient D. The same data are also reported at their temperature‐dependent long‐time limits. The results suggest a sudden, faster than one second, collapse and intermolecular aggregation into globules and a slower reorganization/redistribution of the individual chains among and within the globular and mobile states. We found that all molecular changes are reversible if the temperature remains less than ca. 6–8 K above the LCST for less than a few minutes; under those conditions, experiments upon sudden temperature quench below the LCST show that the aggregates disintegrate and swell into coils in less than a few seconds.

¹H NMR signal intensity of the methyl groups of 1 wt.‐% PNIPAM dissolved in 0.1 M NaCl solution in D₂O in a temperature‐jump experiment from 300 to 312 K. The data were recorded by the 90°?τ–(180°?2τ‐)_n‐detection of the CPMG pulse sequence.     

THE EFFECT OF KINESIO? TAPE ON VERTICAL JUMP AND DYNAMIC POSTURAL CONTROL

Introduction and Background:

Ankle injuries are one of the most common injuries among physically active individuals. The role of prophylactic ankle taping and bracing has been studied extensively. Kinesio^® Tape (KT) is a somewhat new type of taping technique gaining popularity as both treatment and performance enhancement tool. However, there is limited research on the effect of KT on functional performance.

Purpose:

The purpose of this study was to determine whether the application of Kinesio Tex^® Tape had an effect on vertical jump and dynamic postural control in healthy young individuals.

Methods:

52 healthy subjects free of ankle or lower extremity problems (28 males and 24 females; age: 22.12±2.08 years; height: 170.77±8.69 cm; weight: 69.90±12.03 kg) participated in the study. Subjects were randomly assigned to either the experimental group (KT with tension) or the control group (KT without tension). Vertical jump was measured using the VertiMetric device and dynamic postural control was assessed using the Star Excursion Balance Test (SEBT) under three conditions: (1) without taping; (2) immediately after taping; (3) 24 hours after taping with the taping remaining in situ.

Results:

Three-way repeated measure ANOVA was conducted in order to identify differences between the experimental and the control group during the three conditions. Overall, there were no differences between groups in vertical jump maximum height, vertical jump average height, or the SEBT scores for the three time periods (pre-test, post-test, 24hrs-post-test). However, the main effect of KT was moderated by a significant gender interaction, resulting in a statistically significant effect of KT for the SEBT scores in the posterior-medial direction, F(1.72, 82.57) = 4.50, p = 0.018 and the medial direction, F(1.75, 83.81) = 4.27, p = 0.021. Follow-up analyses indicated that female subjects in the KT group had increased SEBT scores between three time periods when compared to the placebo group.

Discussion:

KT application on the ankle neither decreased nor increased vertical jump height in healthy non-injured young individuals, but did increase dynamic postural control in females for certain directions. Additional study is warranted using different measures of balance to further investigate the effect of KT on dynamic postural control.

Level of Evidence:

2b     

Influence of falling height on the excitability of the soleus H-reflex during drop-jumps

Aim: The stretch‐shortening cycle (SSC) is characterized by stretching of the target muscle (eccentric phase) prior to a subsequent shortening in the concentric phase. Stretch reflexes in the eccentric phase were argued to influence the performance of short lasting SSCs. In drop‐jumps, the short latency component of the stretch reflex (SLR) was shown to increase with falling height. However, in jumps from excessive heights, the SLR was diminished. So far, it is unclear whether the modulation of the SLR relies on spinal mechanisms or on an altered fusimotor drive. The present study aimed to assess the spinal excitability of the soleus Ia afferent pathway at SLR during jumps from low height (LH – 31 cm) and excessive height (EH – 76 cm). Methods: In 20 healthy subjects (age 25 ± 3 years), H‐reflexes were timed to occur at the peak of the SLR during drop‐jumps from LH and EH. Results: H‐reflexes were significantly smaller at EH than at LH (P < 0.05). Neither soleus and tibialis anterior background EMG nor the size of the maximum M‐wave changed with falling height. Conclusion: Differences in the H‐reflex between EH and LH indicate that spinal mechanisms are involved in the modulation of the SLR. A decreased excitability of the H‐reflex pathway at EH compared with LH is argued to serve as a ‘prevention strategy’ to protect the tendomuscular system from potential injuries caused by the high load. It is argued that pre‐synaptic inhibition of Ia afferents is most likely responsible for the change in H‐reflex excitability between the two jump conditions.