This letter presents an active-type twisted string actuator (TSA)-based continuously variable transmission (CVT). The proposed mechanism improves the advantage of the intrinsic CVT nature of TSA by ...compensating its nonlinear transmission ratio (TR) with the active and continuous conversion of the TR during contraction at a constant load as well as variable load. To change the TR, the proposed CVT adjusts the ratio of rotation between individual twists and overlap twists, which are two different types of string-twisting patterns. The performance of the TSA-based active CVT was experimentally assessed with the fabricated prototype and compared with a mathematical model. This adjustment in the rotation ratio between individual and overlap twists is realized using a planetary gear. By adjusting the rotating speed ratio between the sun and ring gear, the ratio of rotation between individual and overlap twists can be adjusted. Unlike the conventional TSA-based CVT, the proposed CVT can actively and continuously change the TR independent of the external load, even during operation. Consequently, it allows an increase in the operating range of the TSA while maintaining a high contraction speed.
In a laser-plasma electron acceleration, the quality of electron beams is sensitive to the parameters of a laser and a plasma density. With a given laser, higher plasma density may be good for higher ...charge, while lower density is better for longer acceleration channel, generating higher peak energy at the expense of charge. The dependence of electron beam parameters on the plasma density is, therefore, crucial to find the operating condition for applications. After the target chamber is evacuated, the plasma density and the focal position of the laser beam in the plasma channel can be remotely controlled during the experiments. The plasma density can be obtained by extracting the phase information from captured interferogram, followed by numerically computing the integral derived using Abel inversion. We suggested the simple idea of FFT Filtering and Reconstructing (FR), to be processed prior to a typical computing process, which is the continuous wavelet transform (CWT) for phase shift and the Fourier–Hankel transform (FH) for the integral of Abel inversion here. The FFT filtering can suppress the errors due to the noise, while the reconstructing can select the different data points between the fringes to reduce the systematic error and improve the visibility in interferograms. We confirm the FR-CWT-FH method can provide the average plasma density in uniform region and the longitudinal channel structure with high accuracy, letting the in-situ monitoring possible. The fringe spacing in reconstruction and the wavelet frequency in CWT can be selected differently depending on the shape of plasma density, such as uniform or rising (or falling), and its length of each region to obtain the detailed structure of plasmas.
Strong enhancement in proton energy was investigated from a two-dimensional particle-in-cell simulation where an ultraintense laser pulse irradiates a 2-μm thick metal foil coated with a low density, ...1-μm thick PMMA (polymethylmathacrylate - C5H8O2) on the rear surface. The reduction of PMMA density effectively increases resistivity of hot electrons, which results in the generation of a strong electrostatic field at the metal-PMMA interface in addition to the sheath electrostatic field at the PMMA-vacuum boundary. The interaction of each proton beam accelerated by the two electrostatic fields leads to the enhancement of energy for the protons originated from the PMMA-vacuum side. With a laser intensity of 1×1020 W/cm2, maximum proton energy of 80 MeV was investigated with a modulation in energy spectrum, which is 2.2 times higher than those from a metal-contamination layer target or a metal-high density PMMA target. It is also interesting that there is an energy peak around 18 MeV, which is caused by an interaction with heavier ions.
Carbon ions and protons from a double-layer target, a copper foil coated with a polymer exhibit non-Maxwellian spectral shapes, when an ultra-intense laser pulse with a high temporal contrast ratio ...was focused on the metal side of the target. The spectral shapes, showing strong reduction of low-energy ions, a high-energy island, and a modulated structure, are different from a typical thermal distribution usually obtained from a pure metal target in the laser acceleration of ions. In the case of C
6
+
ion, a high-energy island with an energy spread of 0.5 MeV/u was observed, which is separated from the low-energy spectrum by 0.2 MeV/u. A modulation in the proton energy spectrum was observed, which leads to a secondary peak at 2.2 MeV/u in addition to a peak at a low energy of 1.5 MeV/u. The maximum energy obtained from the double-layer target at a laser intensity of 3
×
10
20
W/cm
2
is 3.4 MeV/u for C
6
+
ions and 10 MeV/u for protons, which are higher than those obtained from a single metal foil by factors of 1.7 and 1.3, respectively. Such a spectral shape and energy enhancement could be accounted for by a bulk electrostatic field formed at the metal-polymer interface and multi-species interactions. These results show that the spectral shape of the ion beam can be tailored with an adequate structure of micrometer-thick target.
Purpose This study investigated the effects of craniocervical flexion exercise on upper-limb postural stability by measuring upper-limb postural tremor during a goal-directed pointing task. Subjects ...and Methods Twenty-four subjects were randomly assigned to the exercise or control group. The exercise group performed craniocervical flexion exercise four days per week for five weeks. Upper-limb postural tremor was measured by using a three-dimensional electromagnetic motion tracking system (trakSTAR™, Ascension Technology Corporation, Burlington, VT, USA) during a goal-directed pointing task. Results In the exercise group, the range and velocity of the trajectories of the shoulder, wrist, and finger in the lateral direction improved significantly. However, no significant changes were observed in the control group. Conclusion Craniocervical flexion exercise reduces the range and velocity of upper-limb postural tremor, thereby increasing postural stability.
Purpose The present study reviewed studies that examined the effects of attentional focus on balance. Methods Keywords such as “attentional”, “focus”, and “balance” were used to find relevant ...research papers in PubMed (www.ncbi.nlm.nih.gov/pubmed). Forty-five papers were found, and 18 of them were used for this study, excluding review papers and papers irrelevant to the topic of this study. Results Among the papers used for the review, the number of papers in which external focus produced effective outcomes was 15 (83.3%). The number of papers in which both external and internal focus produced effective outcomes was 2 (11.1%). The number of paper in which no instruction about attentional focus was effective was 1 (5.5%), and the number of papers in which internal focus was effective was zero. Conclusion This short review suggests clinical implications about how physical therapists can use attentional focus for balance rehabilitation of patients. Instructions about external focus of attention can generally be useful as a method to improve posture and balance control. Furthermore, the present reviews indicates that external focus of attention would be more useful in a rehabilitation stage in which the difficulty level of balance performance is gradually increased.
Purpose Proprioceptive neuromuscular facilitation (PNF) stretching is known to be effective in increasing joint ROM. The PNF stretching technique first induces an isometric contraction in the muscles ...to be stretched, but no agreement concerning the optimal contraction intensity has yet been reached. The purpose of the present study was to examine the effect of contraction intensity on ROM while applying PNF stretching. Subjects and Methods Sixty male subjects were randomly assigned to one of four groups (three experimental groups and one control group). Each experimental group applied one of three contraction intensities (100%, 60%, and 20%) defined by the MVIC ratio, and the control group did not receive any intervention during the experiment. PNF stretching was applied to left knee extensors to compare changes in the knee joint flexion angle. Results The results showed that the changes in ROM were larger for the 60% and 100% groups compared with the 20% group. The changes in ROM were lowest in the control group. Conclusion The present results indicate that while applying the PNF stretching, it is not necessary to apply the maximum intensity of muscle contraction. Moderate isometric contraction intensities may be optimal for healthy young males, while a sufficient effect can be obtained even with a low contraction intensity.
Abstract
Myeloproliferative neoplasms (MPNs) are clonal hematopoietic stem cell disorders characterized by the expansion of myeloid lineage cells. Chronic myeloid leukemia (CML) is characterized by a ...BCR-ABL1 fusion gene that causes constitutive tyrosine kinase activity. Polycythemia vera, essential thrombocythemia, and primary myelofibrosis (PMF) are frequently associated with driver mutations in genes such as JAK2, CALR, and MPL and are mutually exclusive of BCR-ABL1. Herein, we report the first case study of a patient diagnosed with accelerated-phase CML while undergoing treatment for initial JAK2 V617F–positive, BCR-ABL1-negative PMF. This finding emphasizes the importance of BCR-ABL1 testing in patients with an atypical BCR-ABL1-negative MPN disease course.
: Individuals in the later stages of cerebellar ataxia usually experience serious balance and immobility problems. Currently, there is a lack of adequate rehabilitative programs for individuals with ...severe cerebellar ataxia that can help improve ataxia-related motor impairment. The purpose of the present study was to explore the potential physiotherapeutic benefits of partnered dance on balance, motor functions, and psychological well-being in an individual demonstrating severe cerebellar ataxia symptoms.
: The individual was a 39-year-old male diagnosed with cerebellar atrophy. He had the disease for more than 15 years prior to the study. The individual attended 24 intervention sessions over an 8-week period of dance-based movement training that aimed to improve his balance and postural stability by facilitating the perception and control of static and dynamic balance movements and body alignment.
: The individual demonstrated improvements in independent standing balance, gait characteristics, and functional mobility. In addition, improvements in self-reported depression and quality of life scores were observed after completion of the intervention.
: Although interpreting the findings of this study is limited to a single participant, partnered dance could be a suitable alternative physiotherapeutic intervention method for people with severely impaired mobility due to cerebellar dysfunction.
Purpose This study applied whole body vibration (WBV) at different vibration frequencies to chronic stroke patients and examined its immediate effect on their postural sway. Subjects and Methods A ...total of 14 (5 males, 9 females) stroke patients participated. The subjects were randomly assigned to one of the two vibration frequency groups (10 Hz and 40 Hz). Right before and after the application of WBV, the subjects performed quiet standing for 30 seconds, and COP parameters (range, total distance, and mean velocity) were analyzed. Results The 10 Hz WBV did not affect the postural sway of stroke patients. The 40 Hz WBV increased postural sway in the ML direction. Conclusion The results suggest that WBV application to stroke patients in the clinical field may have adverse effects and therefore caution is necessary.
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