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High Field ESR Measurements on One Dimensional Antiferromagnetic Zigzag Chain Systems
Hitoshi Ohta,Susumu Okubo,Kousuke Shiraki,Makoto Yoshida,Alexei A. Belik,Masaki Azuma 한국물리학회 2008 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.53 No.2
In order to study the dynamical properties of the S = 1/2 one-dimensional zigzag chain anti-ferromagnet PbCuP2O7, we performed high field electron spin resonance (ESR) measurements of powder and magnetically aligned samples of PbCuP2O7 by using pulsed magnetic fields up to 15 T in the temperature range from 1.7 to 265 K. Dynamical properties, such as the increases in the g-value and the linewidth at low temperature, are observed. By the aid of a direct numerical ESR calculation, the observed g-shift can be understood only by assuming the Dzyaloshinski-Moriya interaction in the system. This is a new approach to determine the Dzyaloshinski-Moriya interaction in a S = 1/2 one-dimensional antiferromagnet.
Masafumi Maruyama,Arito Yozu,Yoshikazu Okamoto,Hitoshi Shiraki 대한운동학회 2021 아시아 운동학 학술지 Vol.23 No.3
[OBJECTIVES] Medial heel wedges are commonly prescribed to manage the weight-bearing response of hindfoot valgus and the total weight-bearing responses of the navicular and talus bones. Previous studies have reported that a medial heel wedge is effective in the management of musculoskeletal injuries. However, it remains unclear the effect of a medial heel wedge on the weight-bearing responses of foot-arch bones in vivo. To clarify the effects of a medial heel wedge on the weight-bearing response of hindfoot valgus and the total weight-bearing responses of the navicular and talus bones is necessary to understand how best to treat musculoskeletal injuries clinically. The purpose of our study was to clarify the effects of a medial heel wedge on the weight-bearing response of hindfoot valgus and the total weight-bearing responses of the navicular and talus bones. [METHODS] Twenty-five healthy males were analyzed. We obtained MRI scanning of the right foot under non-loading (NL) and full weight-bearing (FW) conditions. Participants wore two insole types, a flat insole and a medial heel wedge. To evaluate the weight-bearing response in hindfoot valgus, the hindfoot alignment view (HAV) was measured. We also measured navicular and talus bone positions and calculated the total positional changes of the navicular and talus bones (ΔTPCN, ΔTPCT) from the vertical and medial displacements using the Pythagorean theorem. [RESULTS] Significant interactions were observed with the HAV. Under both NL and FW conditions, the HAV was smaller on the medial heel wedge than on the flat insole. In addition, the ΔTPCN was significantly smaller on the medial heel wedge than on the flat insole. However, no significant differences were observed for ΔTPCT. [CONCLUSIONS] Our results suggest that use of a medial heel wedge decreases hindfoot valgus values under both NL and FW conditions and stabilizes the total weight-bearing response of the navicular bone.
Sonoko Mashimo,Naruto Yoshida,Ayaka Takegami,Yuki Warashina,Hitoshi Shiraki 대한운동학회 2019 아시아 운동학 학술지 Vol.21 No.2
[OBJECTIVES] To understand the condition of athletes engaged in daily sports activities, it is important to investigate the pain that many such athletes can experience as well as the pain that can be an initial symptom of injury. Although handball is a contact sport associated with frequent injuries, the actual nature of pain symptoms that develop has not been sufficiently studied, and the relationship between pain occurrence and athletes’ daily changing physical load remains unclear. This study aimed to clarify the nature of pain symptoms in handball players and examine the relationship between pain occurrence and physical load. [METHODS] This study involved a 12-month daily assessment of pain symptoms and physical load involving 11 university female handball players. Pain was examined in terms of body region and a pain severity score using a pain questionnaire, and physical load on handball was assessed based on playing hours, types of matches and training recorded by a video camera. [RESULTS] The total number of pains was 1698, and the pain incidence rate was 288.1 pains per 1000 player hours. In terms of body regions, the ankle (18.3%) was the most common, followed by the lower back (13.3%), foot (12.8%), Achilles tendon (9.2%), and thigh (8.9%). With regard to the relationship between pain and physical load, significant moderate or weak correlations were observed between handball (rs=0.657), training (rs=0.626), and on-court training (rs=0.591) and overall pain occurrences. In terms of body regions, the ankle and thigh, significant moderate or weak correlations were observed with respect to all categories in on-court training. [CONCLUSIONS] We found that pain occur frequently and athletes continue to compete in games despite experiencing pain. In addition, pain occurrence was related to physical load, indicating that the type of physical load depends on the body region.
Orignal Paper : High circulating Levels of oxidized LDL in strength-trained athletes
( Seiji Maeda ),( Young Ju Choi ),( Mutsuko Yoshizawa ),( Kai Tanabe ),( Asako Miyaki ),( Yoko Tanabe ),( Hitoshi Shiraki ),( Ryuichi Ajisaka ),( Hidehiko Komine ) 한국운동영양학회 2011 Physical Activity and Nutrition (Phys Act Nutr) Vol.15 No.2
Oxidized low-density lipoprotein (oxLDL) has been shown to play a major role in the progression of atherosclerosis and cardiovascular disease. Aerobic exercise training has been reported to decrease plasma oxLDL levels. However, until now, there have been no studies regarding the effect of strength exercise training on plasma oxLDL levels. The purpose of this study was to investigate the plasma oxLDL. concentration and antioxidant capacity of plasma in strength-trained athletes. We specifically assessed the total scavenging activity against plasma hydroxyl radical (HO,) and alkoxyl radical (RO,) by using the electron spin resonance (ESR) technique, as both radicals are involved in oxLDL production. The subjects included young strength-trained athletes (SA group; shot put, hammer, javelin throwers, or power lifters; n=9) and sedentary individuals (control group; n=9). We measured plasma oxLDL concentrations and total scavenging activity against HO, and RO. Maximal muscle strength, as assessed by isokinetic tests of the knee and elbow joints and maximal handgrip strength, was significantly greater in the SA group than in the control group. Plasma oxl.DL concentrations were found to be significantly higher in the SA group than in the control group. The total scavenging activity of plasma against HO, and RO. did not differ between the two groups. These results suggest that high-intensity strength training increases plasma oxLDL concentration without upregulating the total scavenging activity against plasma HO, and RO.