Horizontal Hop Research Articles

주기적 모니터링 센서 네트워크에서 핫 스팟 문제 해결을 위한 호핑 라우팅 기법

Abstract In this paper we proposed a hopping routing scheme to resolve the hot spot problem for periodic monitoring services in wireless sensor networks. Our hopping routing scheme constructs load balanced routing path, where an amount of energy consumption of all nodes in the sensor networks is predictable. Load balanced routing paths can be obtained from horizontal hopping transmission scheme which balances the load of the sensor nodes in the same area, and also from vertical hopping transmission scheme which balances the load of the sensor nodes in the other area. The direct transmission count numbers as load balancing parameter for vertical hopping transmission are derived using the energy consumption model of the sensor nodes. The experimental results show that the proposed hopping scheme resolves the hot spot problem effectively. The efficiency of hopping routing scheme is also shown by comparison with other routing scheme such as multi-hop, direct transmission and clustering.Key Words : Hot Spot Problem, Hopping Routing, Load Balanced Routing Path

Bilateral Comparison And Reliability Of Ground Reaction Forces During Single Leg Hop Test

PURPOSE: To compare single leg horizontal hop ground reaction forces (GRF) between the dominant (DOM) and non-dominant (NDOM) limbs and to determine the reliability GRF based variables. METHODS: After a standardized warm-up, 20 (10 men, 10 women) physically active (Tegner score = 6.5 +/- 1.7, range 4-9) young adults (21.7 +/- 2.1 yrs) performed three DOM and three NDOM single leg horizontal hops in random order during two sessions 72 hours apart. In addition to recording hop distance, GRF were used to calculate 10 variables using the vertical (vGRF) and anterior-posterior (apGRF) GRF: peak, peak to ground off (GO), impulse, average force, and impulse time. Reliability was assessed across session one trials (intrasession) and between sessions one and two (intersession) using intraclass correlation coefficients (ICC) and standard error of measurement. Separate two factor analysis of variance were conducted to assess interactions between limb (DOM, NDOM) and direction (vGRF, apGRF) using the session one three trial average. The relationship between hop distance and GRF variables were established using correlational analyses. RESULTS: No significant hop distance difference was found (t19 = -.840, P =.412) between the NDOM (1.07 ±.12 % ht, 95% CI: 1.03 - 1.09)(and DOM (1.06 ±.11 % ht, 95% 1.02 - 1.08) limbs. Similarly there were no significant limb differences (interactions or main effects) for any of the GRF variables (P>.05). A significant direction main effect was observed for peak (vGRF>aGRF, PaGRF, P<.001), average force (vGRF>aGRF, PvGRF, P.75) with the exception of intrasession vGRF peak to GO (both limbs). Four GRF variables significantly related to hop distance: DOM vGRF impulse (r =.480, P =.032), DOM aGRF peak (r =.524, P =.018), DOM aGRF impulse (r =.677, P =.001) and NDOM aGRF impulse (r =.765, P<.001). CONCLUSION: Equal hop distances and underlying GRF may be expected between DOM and NDOM in healthy individuals. Except vGRF peak to GO, all GRF based variables were reliable. Further research is needed to determine if GRF analyses increases the sensitivity of the single leg hop test in identifying performance deficits, and/or injury predisposition.

Isokinetic assessment of patellofemoral pain syndrome: A prospective study in female recruits

Objective: To investigate prospectively the influence of muscular parameters on the development of the patellofemoral pain syndrome (PFPS) in women during a basic military training. Methods: Before the military training, 62 healthy female recruits, aged 18-34 years, without a history of PFPS, underwent an isokinetic test ( concentric contractions of knee flexors and extensors at 60 degrees/s and 240 degrees/s, eccentric contractions at 30 degrees/s). They also completed a questionnaire and performed a single-leg horizontal hop test. After basic military training, they underwent a clinical evaluation to assess PFPS. Independent t-tests and chi-square tests were used to evaluate whether any significant difference existed prior to the development of PFPS between females with and without PFPS. Results: The incidence of PFPS was 42%. Significantly lower peak torque of the extensors at 60 degrees/s and 240 degrees/s were observed in females with PFPS compared to the control group. The relative peak extensor torque per body weight and BMI, the ratio peak torque flexors/extensors and the sports participation were also significantly lower in the PFPS group. Conclusions: Decreased quadriceps strength and insufficient sports participations seem to be risk factors for the development of PFPS. Consequently, strengthening of quadriceps seems an important parameter in the treatment and prevention of PFPS.

Leg kinematics and kinetics in landing from a single-leg hop for distance. A comparison between dominant and non-dominant leg

Anterior cruciate ligament (ACL) deficiency can be a major problem for athletes and subsequent reconstruction of the ACL may be indicated if a conservative regimen has failed. After ACL reconstruction signs of abnormality in the use of the leg remain for a long time. It is expected that the landing after a single-leg hop for distance (horizontal hop) might give insight in the differences in kinematics and kinetics between uninjured legs and ACL-reconstructed legs. Before the ACL-reconstructed leg can be compared with the contralateral leg, knowledge of differences between legs of uninjured subjects is needed. Kinematic and kinetic variables of both legs were measured with an optoelectronic system and a force plate and calculated by inverse dynamics. The dominant leg (the leg with biggest horizontal hop distance) and the contralateral leg of nine uninjured subjects were compared. No significant differences were found in most of the kinematic and kinetic variables between dominant leg and contralateral leg of uninjured subjects. Only hop distance and hip extension angles differed significantly. This study suggests that there are no important differences between dominant leg and contralateral leg in healthy subjects. As a consequence, the uninvolved leg of ACL-reconstructed patients can be used as a reference. The observed variables of this study can be used as a reference of normal values and normal differences between legs in healthy subjects.

Effect of Fatigue on Single-Leg Hop Landing Biomechanics

The objective of this study was to measure adaptations in landing strategy during single-leg hops following thigh muscle fatigue. Kinetic, kinematic, and electromyographic data were recorded as thirteen healthy male subjects performed a single-leg hop in both the unfatigued and fatigued states. To sufficiently fatigue the thigh muscles, subjects performed at least two sets of 50 step-ups. Fatigue was assessed by measuring horizontal hopping ability following the protocol. Joint motion and loading, as well as muscle activation patterns, were compared between fatigued and unfatigued conditions. Fatigue significantly increased knee motion (p = 0.012) and shifted the ankle into a more dorsiflexed position (p = 0.029). Hip flexion was also reduced following fatigue (p = 0.042). Peak extension moment tended to decrease at the knee and increase at the ankle and hip (p = 0.014). Ankle plantar flexion moment at the time of peak total support moment increased from 0.8 (N x m)/kg (SD, 0.6 [N x m]/kg) to 1.5 (N x m)/kg (SD, 0.8 [N x m]/kg) (p = 0.006). Decreased knee moment and increased knee flexion during landings following fatigue indicated that the control of knee motion was compromised despite increased activation of the vastus medialis, vastus lateralis, and rectus femoris (p = 0.014, p = 0.014, and p = 0.017, respectively). Performance at the ankle increased to compensate for weakness in the knee musculature and to maintain lower extremity stability during landing. Investigating the biomechanical adaptations that occur in healthy subjects as a result of muscle fatigue may give insight into the compensatory mechanisms and loading patterns occurring in patients with knee pathology. Changes in single-leg hop landing performance could be used to demonstrate functional improvement in patients due to training or physical therapy.

Long-distance radical cation transport in DNA: horizontal charge hopping in a dimeric quadruplex

A series of DNA hairpins were synthesized and shown to associate to form quadruplexes formed by stacking five G-quartets in an antiparallel orientation. One of the hairpins in the quadruplex was linked covalently at the 5'-end to an anthraquinone (AQ) group and a 32P label was incorporated either at the 3'-terminus of the AQ-containing hairpin or on its partner hairpin in the quadruplex. Irradiation of the AQ group with UV light leads to the one-electron oxidation of the DNA and concomitant introduction of a radical cation into the DNA. Analysis by PAGE and autoradiography shows that the radical cation reacts at guanines both on the AQ-containing strand and with its partner hairpin in the quadruplex. This observation demonstrates that charge migration in DNA occurs vertically along a DNA chain and horizontally within a G-quartet.

Number of Repetitions to Maximum in Hop Tests in Patients with Anterior Cruciate Ligament Injury

The unilateral horizontal, triple cross-over and vertical hops are commonly used as outcome measures after knee injury but there is little knowledge of the number of repetitions needed to reach maximum performance. Seventy subjects who had either an anterior cruciate ligament deficient or reconstructed knee participated in this study. Unilateral vertical, horizontal, and triple cross-over hop testing was applied to each leg until two consecutive decrements in performance occurred. The number of repetitions to reach maximum during these tests were calculated. Fifteen repetitions of the horizontal and vertical hops, and 10 repetitions of the triple-crossover hop enable distances to be achieved that are acceptably close to maximal levels in these knee-injured patients. In order to increase the likelihood of finding a patient's maximum hop performance after knee injury, more repetitions are suggested than has been reported in the literature.

Test-Retest Reliability of 4 Single-Leg Horizontal Hop Tests

The purpose of this study was to determine the test-retest reliability of 4 single-leg horizontal hop tests (i.e., single hop for distance, triple hop for distance, crossover hop for distance, and 6-m hop for time), with a time interval of approximately 4 weeks separating the 2 testing sessions. Eighteen healthy, young, adult men, all cadets enrolled at the U.S. Air Force Academy, Colorado, performed the single hop for distance, the triple hop for distance, the crossover hop for distance, and the 6-m hop for time during 2 testing sessions separated by 31.2 ± 0.4 days. Reliability data for each of the single-leg hop tests were studied through a repeated measures analysis of variance, intraclass correlation coefficients (ICCs), and standard errors of measurement (SEMs). The ICCs ranged from 0.92 to 0.97 for the 4 single-leg hop tests. The SEMs for the single-leg hop tests that assessed the distance hopped ranged from 4.61 to 17.74 cm. The SEM for the 6-m hop for time test was 0.06 seconds. No significant differences were noted when the mean scores of the 2 test trials were compared by a repeated measures analysis of variance for any of the single-leg hop tests. These results indicate that the single-leg hop tests examined in this study offer strength and conditioning professionals a reliable method to assess the single-leg horizontal hopping capabilities of healthy, young, adult men, with intervals of approximately 4 weeks between testing sessions.

Test-Retest Reliability of 4 Single-Leg Horizontal Hop Tests

The purpose of this study was to determine the test-retest reliability of 4 single-leg horizontal hop tests (i.e., single hop for distance, triple hop for distance, crossover hop for distance, and 6-m hop for time), with a time interval of approximately 4 weeks separating the 2 testing sessions. Eighteen healthy, young, adult men, all cadets enrolled at the U.S. Air Force Academy, Colorado, performed the single hop for distance, the triple hop for distance, the crossover hop for distance, and the 6-m hop for time during 2 testing sessions separated by 31.2 +/- 0.4 days. Reliability data for each of the single-leg hop tests were studied through a repeated measures analysis of variance, intraclass correlation coefficients (ICCs), and standard errors of measurement (SEMs). The ICCs ranged from 0.92 to 0.97 for the 4 single-leg hop tests. The SEMs for the single-leg hop tests that assessed the distance hopped ranged from 4.61 to 17.74 cm. The SEM for the 6-m hop for time test was 0.06 seconds. No significant differences were noted when the mean scores of the 2 test trials were compared by a repeated measures analysis of variance for any of the single-leg hop tests. These results indicate that the single-leg hop tests examined in this study offer strength and conditioning professionals a reliable method to assess the single-leg horizontal hopping capabilities of healthy, young, adult men, with intervals of approximately 4 weeks between testing sessions.

Polypropylene braid augmented and nonaugmented intraarticular anterior cruciate ligament reconstruction.

The purpose of this clinical retrospective study is to determine whether a polypropylene braid (PB) used to augment an intraarticular autograft to reconstruct the anterior cruciate ligament (ACL) is safe and to determine whether the PB improves the efficacy of the procedure. A simultaneous review was performed of patients who had undergone an intraarticular ACL reconstruction using an autograft composed of the central quadriceps tendon, prepatellar periosteum, and patellar tendon left attached distally to the tibial tubercle and of patients who had undergone the same procedure with PB augmentation of the autograft. Preoperatively, all patients had chronic ACL insufficiency and were experiencing symptomatic giving way. A subjective questionnaire and a physician examination (JHR) were completed on each patient. Objective laxity and functional testing, including KT 1000 arthrometer measurement, Cybex isokinetic strength analysis, and one leg horizontal hop for distance, were performed. Six radiographs of each operated knee were obtained. Results were statistically analyzed. Thirty-eight of 43 (88%) nonaugmented procedures performed were reviewed, with a mean followup of 64 months. Forty-five of 48 (94%) PB augmented reconstructions with a minimum followup of 42 months (maximum 57 months, mean 50 months), were reviewed. On objective laxity and function testing, the PB augmented patients had better results than the nonaugmented patients. On subjective questioning, physician's examination, and radiographic analysis, the PB augmented results were significantly better. There were 12 (32%) knees with recurrent symptomatic giving way in the nonaugmented group and 5 (11%) in the PB augmented group. Chrondromalacia patellae and arthrofibrosis were seen in both groups. No adverse reaction to the PB was seen. We conclude that the PB is safe and that PB augmentation improves the efficacy of the intraarticular autograft to reconstruct the ACL.