oalib

OALib Journal期刊

ISSN: 2333-9721

费用：99美元

投稿

时间不限

( 2022 )

( 2021 )

( 2020 )

( 2019 )

自定义范围…

匹配条件： “ Yoshihiko Kuwahara” ，找到相关结果约798条。
列表显示的所有文章，均可免费获取
第1页/共798条
每页显示 条
Near Field Microwave Holography for Bio-Tissue Imaging  [PDF]
Yoshihiko Kuwahara, Kimihito Fujii
Open Journal of Medical Imaging (OJMI) , 2020, DOI: 10.4236/ojmi.2020.103014
Abstract: This study investigated the ability of microwave holography to accurately reconstruct the tissue structure of the human body. Numerical breast and head phantoms were imaged by 3D near-field holography using backscattered waves obtained by a monostatic planar scan. Complex organizational structures have been reconstructed accurately and quickly. In addition, breasts with relatively simple histology could be reconstructed without the matching liquid.
Large Scale Analysis of Complex Permittivity of Breast Cancer in Microwave Band  [PDF]
Yoshihiko Kuwahara, Akira Nozaki, Kimihito Fujii
Advances in Breast Cancer Research (ABCR) , 2020, DOI: 10.4236/abcr.2020.94008
Abstract: To obtain some prior knowledge of breast cancer detection by microwave imaging, we have measured and analyzed the complex permittivity of tissues extracted from over 140 breast cancer surgeries. The relative permittivity and conductivity of tumor at 1.6 GHz were 17.5% and 16.2% higher than those of mammary gland tissue, respectively. In invasive ductal carcinoma of scirrhous type, 8 out of 64 had higher relative permittivity and conductivity of mammary gland than those of tumor. However, when evaluated by the Debye parameter considering the frequency dependence of the tissue, it is rare that ε∞ and Δε of cancer are simultaneously lower than those of mammary gland. The relative permittivity and conductivity of fibroadenoma are almost the same as those of mammary glands. The relative permittivity and conductivity of each tissue showed strong linearity. Microwave imaging requires accurate reconstruction of ε∞ and Δε to distinguish cancer from normal tissue.
Development of Non-Contact Detection of a Charged Conductor and Visualization System  [PDF]
Kazuma Nogi, Yoshihiko Kuwahara, Takuji Ushimoto
Open Journal of Safety Science and Technology (OJSST) , 2021, DOI: 10.4236/ojsst.2021.111002
Abstract: At a substation, the condition of an applied voltage is checked using a bulky contact-type electroscope. Although it is important to secure a safe working environment, it is a burden to workers. In addition, in an emergency investigation or at the time of an accident, an operator may erroneously recognize a power interruption and cause an electric shock. Therefore, it is desirable to develop technology that can easily distinguish the charged condition from a distance. In this research, the focus was on the slight vibration of the conductor owing to the Coulomb force generated when a high voltage？was？applied. A system for visualizing the charging state by detecting the vibration with radar and combining it with a stereo camera was developed. Its performance was then confirmed at an experimental site and substation. In addition, the effectiveness of a method that used？independent component analysis to identify the harmonics of the power supply frequency and vibration resulting from the applied voltage was demonstrated.
Steerable Antenna Using Algorithm Based on Downhill Simplex Method
Noorsaliza Abdullah;Yoshihiko Kuwahara
PIER C , 2011, DOI: 10.2528/PIERC11042712
Abstract: Electronically steerable passive array radiator (ESPAR) antennas are expected to gain prominence in the field of wireless communication, because they can be steered toward a desired signal and they can eliminate interference; in addition, they have a very simple architecture that has significantly low power consumption and are inexpensive to manufacture. In this paper, we proposed an ESPAR antenna that has fastest convergence time. The downhill simplex method is used to maximize the correlation coefficient between the received signal and the reference signal. The simulation results indicate that this antenna can be steered toward the desired signal if one signal is used; in addition, it can eliminate interference if two signals, namely, the desired signal and the delayed signal are used by automatically varying the reactance values.
Transient Macroamylasemia in a Severely Multiple-Handicapped Child Following the Development of Acute Bronchitis  [PDF]
Yoshihiko Sakurai
Open Journal of Pediatrics (OJPed) , 2015, DOI: 10.4236/ojped.2015.53035
Abstract: Macroamylasemia is a condition of elevated serum amylase levels in which normal serum amylase form a complex with high molecular weight proteins such as immunoglobulins. This is a case report on a patient with macroamylasemia following acute asthmatic bronchitis. A 5-year-old male with cerebral palsy and developmental retardation was admitted to our hospital because of high fever and severe cough. Treatment of the respiratory symptoms provided symptomatic improvement, but the serum amylase levels became suddenly elevated. Although acute pancreatitis associated with respiratory infection was initially suspected, a predominant salivary isoamylase, normal serum lipase level, low urine amylase level, and low amylase-creatinine clearance ratio (ACCR) (0.58%) indicated macroamylasemia. The serum amylase level decreased, and the ACCR increased within normal range 2 weeks after discharge. Both of these indicators have been within normal range over the past year. Transient macroamylasemia can be misdiagnosed as acute pancreatitis, especially in a severely multiple-handicapped child who is unable to complain. The ACCR is useful in the diagnosis of macroamylasemia.
Early-Stage Juvenile Fibromyalgia in a 12-Year-Old Girl  [PDF]
Yoshihiko Sakurai
Open Journal of Pediatrics (OJPed) , 2015, DOI: 10.4236/ojped.2015.54053
Abstract: Juvenile fibromyalgia (JFM) is often diagnosed at a later stage. Therefore, little is known about its early phase. A 12-year-old girl with persistent lumbago without fever consulted an orthopedist, but imaging studies showed no abnormalities and analgesics were ineffective. She therefore visited our pediatric clinic. On digital palpation, she had pain in 13 of the 18 tender point sites of fibromyalgia. The blood test results were unremarkable. A medical interview revealed character tendencies often seen in patients with JFM; she was serious-minded, uncompromising, and showed excessive concern for others. Furthermore, psychological stress for the approaching annual sports day might have built up. All factors considered, early-stage JFM was the probable diagnosis. The patient accepted the diagnosis and understood that the disease may be psychogenic. Getting through the sports day cured her symptoms. This case highlights the importance of initial care, including a detailed explanation, in those with JFM.
Verbal Abuse, Physical Assault, and Harassment in Pediatric Medical Settings: A Nationwide Survey in Japan  [PDF]
Rie Wakimizu, Hinako Kuwahara
Health (Health) , 2022, DOI: 10.4236/health.2022.142013
Abstract: Background: Verbal abuse, physical assault, and harassment of pediatric healthcare workers by patients and their families have become increasingly serious. These incidents lead to various problems, including the deterioration of staff members’ mental health and employee turnover. Methods: This study was conducted as the first Japanese nationwide survey to assess the abuse perpetrated by patients and families and experienced by medical staff in pediatric medical settings in 2018, countermeasures employed, and staff member evaluations of the countermeasures. Results: Responses from 526 facilities were received, clinics accounted for 79.8% of these facilities; 88.1% of the respondents were females. Further, 10.5% of the facility staff reported having experienced verbal abuse, violence, or harassment from patients or family members. Of 1103 cases of victimizations, there were 719, 136, and 248 cases of verbal abuse, violence, and harassment, respectively. Manuals and guidelines had been created and training and drill performances were conducted as countermeasures in 10.7% and 9.0% of facilities, respectively; 7.3% of staff members felt that the countermeasures were effective, corresponding to 45.6% of the affected staff. Conclusion: The findings suggest the necessity of thoroughly familiarizing staff with existing facility countermeasures as well as introducing new countermeasures such as victimization simulations.
Contributions of Colonic Short-Chain Fatty Acid Receptors in Energy Homeostasis
Atsukazu Kuwahara
Frontiers in Endocrinology , 2014, DOI: 10.3389/fendo.2014.00144
Abstract: The gastrointestinal (GI) tract is separated from the body’s internal environment by a single layer of epithelial cells, through which nutrients must pass for their absorption into the bloodstream. Besides food and drink, the GI lumen is also exposed to bioactive chemicals and bacterial products including short-chain fatty acids (SCFAs). Therefore, the GI tract has to monitor the composition of its contents continuously to discriminate between necessary and unnecessary compounds. Recent molecular identification of epithelial membrane receptor proteins has revealed the sensory roles of intestinal epithelial cells in the gut chemosensory system. Malfunctioning of these receptors may be responsible for a variety of metabolic dysfunctions associated with obesity and related disorders. Recent studies suggest that SCFAs produced by microbiota fermentation act as signaling molecules and influence the host’s metabolism; uncovering the sensory mechanisms of such bacterial metabolites would help us understand the interactions between the host and microbiota in host energy homeostasis. In this review, the contribution of colonic SCFA receptors in energy metabolism and our recent findings concerning the possible link between SCFA receptors and host energy homeostasis are discussed.
Exponential bound on the multipartite couplings in quantum many-body dynamics with long-range interactions
Tomotaka Kuwahara
Physics , 2015,
Abstract: The dynamics of quantum systems usually strongly depends on the local structure of the Hamiltonian. For short-range interacting systems, the well-known Lieb-Robinson bound defines the effective light cone with an exponentially small error with respect to the spatial distance, whereas we can obtain only polynomial bound for long-range interacting systems. In this letter, we derive a qualitatively new bound for quantum dynamics by considering a number of spin which can couple with each other after time evolution. Our bound is exponentially strong with respect to the number of coupling and valid for large class of Hamiltonians including long-range interacting systems. To demonstrate the potential of our approach in quantum many-body systems, we apply our bound to prove several fundamental properties which cannot be derived from the Lieb-Robinson bound.
Spectral gap and the exponential localization in general one-particle systems
Tomotaka Kuwahara
Mathematics , 2014,
Abstract: We investigate the relationship between the spectral gap delta E_0 and the localization length xi in general one-particle systems. A relationship for many-body systems between the spectral gap and the exponential clustering has been derived from the Lieb-Robinson bound, which reduces to the inequality xi le const. times delta E_0^{-1} for one-particle systems. This inequality, however, turned out not to be optimal qualitatively. As a refined upper bound, we here prove the inequality xi le const. times delta E_0^{-1/2} in general one-particle systems. Our proof is not based on the Lieb-Robinson bound, but on our complementary inequality related to the uncertainty principle [T. Kuwahara, J. Phys. A: Math. Theor. 46 (2013)]. We give a specific form of the upper bound and test its tightness in the tight-binding Hamiltonian with a diagonal impurity, where the localization length behaves as xi ~ delta E_0^{-1/2}. We ensure that our upper bound is quantitatively tight in the case of nearest-neighbor hopping.
第1页/共798条
每页显示 条


Home
Copyright © 2008-2020 Open Access Library. All rights reserved.