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Search Results: 1 - 10 of 147 matches for " Ryoko Yahagi "
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Crossover temperature of the spin-1/2 XXZ chain with an impurity
Ryoko Yahagi,Jun Sato,Tetsuo Deguchi
Physics , 2015,
Abstract: We study exactly the effect of an impurity in the interacting quantum spin chain at low temperature by solving the integrable spin-1/2 XXZ periodic chain with an impurity through the algebraic and thermal Bethe ansatz methods. In particular, we investigate how the crossover temperature for the impurity specific heat depends on the impurity parameter, i.e. the coupling of the impurity to other spins, and show that it is consistent with the analytic expression that is obtained by setting the impurity susceptibility to be proportional to the inverse of the crossover temperature. In the model, two types of crossover behavior appear: one from the high-temperature regime to the low-temperature Kondo regime and another from the N-site homogeneous chain to the (N-1)-site chain with a decoupled free impurity spin, with respect to the temperature and the impurity parameter, respectively.
Finite-temperature behavior of an impurity in the spin-1/2 XXZ chain
Ryoko Yahagi,Jun Sato,Tetsuo Deguchi
Statistics , 2014, DOI: 10.1088/1742-5468/2014/11/P11020
Abstract: We study the zero- and the finite-temperature behavior of the integrable spin-1/2 XXZ periodic chain with an impurity by the algebraic and thermal Bethe ansatz methods. We evaluate the impurity local magnetization at zero temperature analytically and derive the impurity susceptibility exactly from it. In the graphs of the impurity specific heat versus temperature, we show how the impurity spin becomes more liberated from the bulk many-body effect as the exchange coupling between the impurity spin and other spins decreases, and also that in low temperature it couples strongly to them such as the Kondo effect. Thus, we observe not only the crossover behavior from the high- to the low-temperature regime but also another one from the $N$-site chain to the $(N-1)$-site chain with a free impurity spin. We also show that the estimate of the Wilson ratio at a given low temperature is independent of the impurity parameter if its absolute value is small enough with respect to the temperature, and the universality class is described by the XXZ anisotropy in terms of the dressed charge.
Energy-momentum conservation laws in Finsler/Kawaguchi Lagrangian formulation
Takayoshi Ootsuka,Ryoko Yahagi,Muneyuki Ishida,Erico Tanaka
Physics , 2014, DOI: 10.1088/0264-9381/32/16/165016
Abstract: We reformulate the standard Lagrangian formalism to a reparameterisation invariant Lagrangian formalism by means of Finsler and Kawaguchi geometry. In our formalism, various types of symmetries that appears in theories of physics are expressed geometrically by symmetries of Finsler (Kawaguchi) metric, and the conservation law of energy-momentum is a part of Euler-Lagrange equations. The application to scalar field, Dirac field, electromagnetic field and general relativity coupled to perfect fluid (added: ver.3) are discussed. By this formalism, we try to propose an alternative definition of energy-momentum current of gravity.
Effects of Nonuniform Outflow and Buoyancy on Drag Coefficient Acting on a Spherical Particle  [PDF]
Mariko Watanabe, Joji Yahagi
Journal of Flow Control, Measurement & Visualization (JFCMV) , 2017, DOI: 10.4236/jfcmv.2017.54008
Abstract: Pyrolysis gas jets out from the surface of a solid fuel particle when heated. This study experimentally observes the occurrence of gas jetsfrom heated solid fuel particles. Results reveal a local gas jet occurs from the particle’s surface when its temperature reaches the point at which a pyrolysis reaction occurs. To investigate the influence of the gas jet on particle motion, a numerical simulation of the uniform flow around a spherical particle with a nonuniform outflow or high surface temperature is conducted, and the drag force acting on the spherical particle is estimated. In the numerical study, the magnitude of the outflow velocity, direction of outflow, and Rayleigh number,?i.e., particle surface temperature, are altered, and outflow velocities and the Rayleigh number are set based on the experiment. The drag coefficient is found to decrease when an outflow occurs in the direction against the mainstream; this drag coefficient at a higher Rayleigh number is slightly higher than that at a Rayleigh number of zero.
Experiences of a Dilated Cardiomyopathy Patient Suffering to Maintain Life Partnership Based on Margaret Newman’s Theory  [PDF]
Ryoko Igarashi
Open Journal of Nursing (OJN) , 2019, DOI: 10.4236/ojn.2019.91004
Abstract: Background: Dilated cardiomyopathy is a refractory myocardial disease with a poor prognosis. Mrs. G experienced cardiopulmonary arrest during hospitalization. She constantly struggles with uncertainty and experiences immense mental suffering from her symptoms, treatments, anxiety, and prognosis. This condition requires appropriate nursing care. Purpose: This study, which is based on Margaret Newman’s theory, aims to clarify the experience of illness of Mrs. G who has dilated cardiomyopathy. Methods: This involved interpretive and dialectical praxis research. The researcher and Mrs. G formed a partnership through discussion. Hermeneutical analysis was performed on the discussion content. Results: The experience of illness of Mrs. G consisted of 6 phases: “Looking back on the shock of having an illness and receiving medical treatment”, “Looking back on one’s life until present”, “Confusion resulting from uncertainty”, “Self-insight”, “Recognizing one’s true feelings of wanting to live”, and “Commitment and decision to live”. Mrs. G could find a new self and expand her consciousness. Conclusion: Mrs. G found meaning in coping with her illness and discovered the value of living while accepting her own destiny. She connected to her own life and became more prepared to live with hope. Thus, partnership in nursing care according to Newman’s theory can benefit patients with distress from dilated cardiomyopathy. This nursing support can improve patient outlook.
N-Body Code with Adaptive Mesh Refinement
Hideki Yahagi,Yuzuru Yoshii
Physics , 2001, DOI: 10.1086/322457
Abstract: We have developed a simulation code with the techniques which enhance both spatial and time resolution of the PM method for which the spatial resolution is restricted by the spacing of structured mesh. The adaptive mesh refinement (AMR) technique subdivides the cells which satisfy the refinement criterion recursively. The hierarchical meshes are maintained by the special data structure and are modified in accordance with the change of particle distribution. In general, as the resolution of the simulation increases, its time step must be shortened and more computational time is required to complete the simulation. Since the AMR enhances the spatial resolution locally, we reduce the time step locally also, instead of shortening it globally. For this purpose we used a technique of hierarchical time steps (HTS) which changes the time step, from particle to particle, depending on the size of the cell in which particles reside. Some test calculations show that our implementation of AMR and HTS is successful. We have performed cosmological simulation runs based on our code and found that many of halo objects have density profiles which are well fitted to the universal profile proposed by Navarro, Frenk, & White (1996) over the entire range of their radius.
Self-Management Behaviors of Patients with Hypertension in Daily Life  [PDF]
Ryoko Igarashi
Open Journal of Nursing (OJN) , 2019, DOI: 10.4236/ojn.2019.96047
Abstract: Background: In a rapidly aging Japanese society, the number of patients with hypertension has seen a steady increase. The basic treatments for hypertension are maintaining blood pressure through medication and preventing complications. It is important for patients with hypertension to perform self-management. This improves their lifestyle while controlling their blood pressure to prevent complications and maintain good health. Purpose: This study aimed to examine the actual self-management behavior ability of patients with hypertension and to clarify the factors involved in their self-management behavior. Methods: A total of 150 patients with hypertension were included in this study. The following data were obtained from the patients as background information: sex, age, years with disease, whether they are receiving antihypertensive agents, type of antihypertensive agent, blood test data, heart thoracic ratio, left ventricular ejection fraction, pulse wave, pulse wave velocity, and height. The levels of self-management skills of the patients were also assessed using the “Instrument to Measure the Self-care of patients with Hypertension” developed by Tsuboi et al. Results: The associations among self-management behaviors in daily life, such as diet, exercise, stress, medication, alcohol intake, and smoking, were analyzed in patients with hypertension. The subjects were classified into the following three groups: aged 65 years or below (Group A), early stage elderly individuals (Group B), and late-stage elderly individuals aged 75 years or over (Group C). The results showed that the subjects in Group C had higher self-management scores for diet, exercise, stress, medication, and drinking than the subjects in the other two groups. The scores of smoking and self-management of the subjects in Group A were high but their other self-management scores were low. All the subjects were taking between 1 to 3 types of oral antihypertensive drugs. The rate of achievement of the target blood pressure was 50% or more in all the three groups. However, the pulse wave velocity was high in all the three groups. Conclusion: The results indicate that the risk of developing disorders of the brain and cardiovascular system is high in all the three groups, owing to the high degree of arteriosclerosis. Therefore, increasing the number of nursing interventions is expected to reduce blood pressure, maintain and promote self-management behavior in daily life, and prevent the onset of complications. The results suggest that nursing interventions involving lifestyle guidance for
Status of Understanding of the Disease and Self-Management Behavior among Patients with Hypertension  [PDF]
Ryoko Igarashi
Health (Health) , 2019, DOI: 10.4236/health.2019.117073
Abstract: Background: Hypertension is a lifestyle-related disease that has no subjective symptoms but could lead to severe complications. The goals of treatment for hypertension are to maintain blood pressure with medications and prevent complications. Measuring blood pressure at home regularly is critical for patients with hypertension. Purpose: This study aimed to 1) clarify the status of patients’ understanding of hypertension and self-management, 2) identify nursing practices that could support patients with hypertension in making them aware of the need for understanding hypertension, monitoring blood pressure at home, and engaging in self-management. Method: A questionnaire survey on understanding of the disease and self-management behavior was conducted among patients with hypertension who regularly visited outpatient clinics. As for data analysis, descriptive statistics were computed for patients’ attributes, clinical findings, understanding of the disease, and self-management behavior. Cross-tabulation and the chi-square test were used for each item on understanding of the disease and self-management behaviors. Results: Data were obtained from 150 participants (93 males and 57 females) with a mean age of 70 years. Patients with a higher understanding of the disease and those who were aware of the target blood pressure were more likely to engage in self-management behavior, including monitoring blood pressure at home, ensuring regular outpatient visits, and consulting with nurses or physicians. In addition, the percentage of patients who recognized the need to achieve their target blood pressure was higher among those who had a spouse and lived with their family. Discussion: Regular monitoring and recording of blood pressure at home are the most important self-management behaviors. Understanding of the disease and self-management behavior and support from the family are critical for maintaining appropriate self-management. Therefore, in cooperation with physicians, nurses should provide health education to patients and their families to enable them to perform appropriate self-management. Health expenditures increase with age, especially in those aged 65 years and over. The prevalence of hypertension increases with age; patients aged 65 years and over need to engage in self-management to maintain their target blood pressure. Nurses should provide patients with hypertension aged 65 years and over with appropriate nursing care to enable them to measure and record their blood
Concomitant Occurrence of Segmental Neurofibromatosis and Lung Adenocarcinoma  [PDF]
Ryoko Morita, Naoki Oiso, Akira Kawada
Journal of Cosmetics, Dermatological Sciences and Applications (JCDSA) , 2012, DOI: 10.4236/jcdsa.2012.24050
Abstract: Neurofibromatosis type 1 (NF1) caused by a loss-of functional mutation in NF1 encoding neurofibromin is an autosomal dominant disorder characterized by café-au-lait spots, neurofibromas, intertriginous freckles, and Lisch nodules. Segmental neurofibromatosis (SN) represents a postzygotic mutation and loss of heterozygosity in neurofibromin. SN occurring in the elder persons may be associated with internal malignant tumors. Here, we reported a case of 58-year-old woman with concomitant occurrence of SN and lung adenocarcinoma. The onset of SN in aged persons would be a sign of concomitant occurrence of internal malignant tumors.
Sources of Sexual Knowledge among Vietnamese High School Students  [PDF]
Kaori Watanabe, Ryoko Saruta, Naomi Kato
Advances in Reproductive Sciences (ARSci) , 2014, DOI: 10.4236/arsci.2014.24010
Abstract: This study determined the sources from which Vietnamese high school students currently acquire sexual knowledge as well as the sources from which they believe they should acquire it. Participants were eleventh-grade students at three public high schools in Hanoi, Vietnam. We conducted a questionnaire-based survey from September to October 2012, with 1672 students participating. Responses were received from all 1672 students, a response rate of 100%. Complete data were received from 1653 respondents (98.9%), including 896 males (54.2%) and 757 females (45.8%). The survey was a self-administrated questionnaire. Although many participants believed that they were knowledgeable about sex, only a small number of them actually possessed accurate sexual knowledge. Few participants in this study, targeted to a specific age (eleventh grade), had used the Internet as a major source for obtaining sexual knowledge, in contrast to results from previous studies which covered a wider age demographic. Future research should include comparative studies between eleventh and twelfth graders as well as between those of the same age who are and who are not enrolled in high school. Additionally, it might be beneficial to consider the relationship between adolescent age and Internet use to study the influence of the Internet on sexual knowledge. Our results suggest that parents and schoolteachers should shoulder more responsibility in providing sexual education, particularly by improving their own knowledge and ability to provide such education, because many participants indicated that sexual knowledge should be acquired from parents and schools.
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