36 research outputs found

    Numerical Simulation of Acoustic Waves in a Two-Dimensional Phononic Crystal: Negative Refraction

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    The lens effect of acoustic waves in a two-dimensional (2D) phononic crystal is studied by numerical simulation based on the finite-difference time-domain (FDTD) method. We calculate the phonon band structure of 2D phononic crystals, consisting of metal cylinders placed periodically in water. Lens effect is observed by the negative refraction of acoustic waves, which results in refocusing of the waves at the point outside the crystal. To increase the focal intensity, we introduce a 2D phononic crystal shield with a different composition of material, which returns the incident waves back to the lens via the perfect reflection. Also, the dependence on filling fraction of metal in the crystal is studied

    FDTD Simulations of Acoustic Waves in Two-DimensionalPhononic Crystals using Parallel Computer

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    The finite-difference time-domain (FDTD) method has been applied to the calculation of the phonon band structure of two-dimensional (2D) phononic crystals, consisting of metal cylinders placed periodically in liquid. By comparing several combinations of materials for metal cylinder and liquid, we analyze the dependence of the band structures on sound speed and density of liquid media. Moreover, the negative refraction of the acoustic waves is observed at the interfaces between phononic crystal slab and the liquid. We find that an acoustic“lens effect”with the slab appears due to the negative refractions. The relationship between the focal intensity in the lens effect and the band structure is discussed

    Cutoff Values of Serum IgG4 and Histopathological IgG4+ Plasma Cells for Diagnosis of Patients with IgG4-Related Disease

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    IgG4-related disease is a new disease classification established in Japan in the 21st century. Patients with IgG4-related disease display hyper-IgG4-gammaglobulinemia, massive infiltration of IgG4+ plasma cells into tissue, and good response to glucocorticoids. Since IgG4 overexpression is also observed in other disorders, it is necessary to diagnose IgG4-related disease carefully and correctly. We therefore sought to determine cutoff values for serum IgG4 and IgG4/IgG and for IgG4+/IgG+ plasma cells in tissue diagnostic of IgG4-related disease. Patients and Methods. We retrospectively analyzed serum IgG4 concentrations and IgG4/IgG ratio and IgG4+/IgG+ plasma cell ratio in tissues of 132 patients with IgG4-related disease and 48 patients with other disorders. Result. Serum IgG4 >135  mg/dl demonstrated a sensitivity of 97.0% and a specificity of 79.6% in diagnosing IgG4-related disease, and serum IgG4/IgG ratios >8% had a sensitivity and specificity of 95.5% and 87.5%, respectively. IgG4+cell/IgG+ cell ratio in tissues >40% had a sensitivity and specificity of 94.4% and 85.7%, respectively. However, the number of IgG4+ cells was reduced in severely fibrotic parts of tissues. Conclusion. Although a recent unanimous consensus of all relevant researchers in Japan recently established the diagnostic criteria for IgG4-related disease, findings such as ours indicate that further discussion is needed

    The Creation of School Education Bringing up a Student Carrying Tomorrow (3) : The Valuation of "Compulsory Subjects", "Optional Subjects", and "Integrated Subjects"

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    The purpose of this study is to show the valuation of "Compulsory Subjects", "Optional Subjects", and "Integrated Subjects", to show the relationship between each subjects and "three abilities", "the ability of recognizing othere senses of value", "the ability of self-expression and communication" and "the ability of decision-making" which defined by the project members. The main result of this study is that we should make up the standards which teachers, students and parents recognize as important abilities

    Formaldehyde Concentration in the Air and in Cadavers at the Gross Anatomy Laboratory in Hiroshima University

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    The formaldehyde concentration in the air and in various tissues of 35 human cadavers were measured during a gross anatomy course held at the Faculty of Medicine of Hiroshima University in the 2003 educational year. Atmospheric formaldehyde levels were 0.25-0.55 ppm and thus less than the upper limit of the guideline for formaldehyde exposure (0.5 ppm) set by the Japan Society for Occupational Health (1988) except for one out of 10 measurements. The formaldehyde concentrations in tissues were as follows: the lung, 0.12 ± 0.09% (n=29); the liver, 0.12 ± 0.09% (n=29); and the brachioradialis muscle, 0.11 ± 0.09% (n=30). Considerable variation was found among the cadavers and these values were lower than those of Tsurumi University which provided the only other data (average formaldehyde concentrations ranged from 0.27 to 0.32%). At Hiroshima University, blood is allowed to drain during embalming, whereas it is not at Tsurumi University. Differences in the embalming procedure are thus responsible for low and fluctuating formaldehyde concentrations in cadavers at Hiroshima University, and it is conceivable that relatively low formaldehyde levels in the air result from low formaldehyde concentrations in cadavers and good room ventilation (10 room-air changes per hour). However, the Japanese Ministry of Health and Welfare recommended lower formaldehyde exposure levels (0.08 or 0.25 ppm) in 2002. Thus, it may be necessary to further reduce formaldehyde levels in the gross anatomy laboratory by means of such measures as neutralizing formaldehyde with ammonium carbonate; using a locally ventilated dissection worktable, etc

    Structure of the rat subcutaneous connective tissue in relation to its sliding mechanism

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    Mammalian skin can extensively slide over most parts of the body. To study the mechanism of this mobility of the skin, the structure of the subcutaneous connective tissue was examined by light microscopy. The subcutaneous connective tissue was observed to be composed of multiple layers of thin collagen sheets containing elastic fibers. These piled-up collagen sheets were loosely interconnected with each other, while the outer and inner sheets were respectively anchored to the dermis and epimysium by elastic fibers. Collagen fibers in each sheet were variable in diameter and oriented in different directions to form a thin, loose meshwork under conditions without mechanical stretching. When a weak shear force was loaded between the skin and the underlying abdominal muscles, each collagen sheet slid considerably, resulting in a stretching of the elastic fibers which anchor these sheets. When a further shear force was loaded, collagen fibers in each sheet seemed to align in a more parallel manner to the direction of the tension. With the reduction or removal of the force, the arrangement of collagen fibers in each sheet was reversed and the collagen sheets returned to their original shapes and positions, probably with the stabilizing effect of elastic fibers. Blood vessels and nerves in the subcutaneous connective tissue ran in tortuous routes in planes parallel to the unloaded skin, which seemed very adaptable for the movement of collagen sheets. These findings indicate that the subcutaneous connective tissue is extensively mobile due to the presence of multilayered collagen sheets which are maintained by elastic fibers

    Repair process of the rat Achilles tendon after tenotomy

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    アキレス腱の修復能力と修復過程について詳細に調べるために,ラットのアキレス腱を切断して,後肢を固定せずに,最長6カ月後まで修復過程を観察した.3日後には腱の断端間(修復部)は,柔らかい結合組織で充たされ,1週後には断端が索状の結合組織で連絡していた.切断した腱の残存部には,線状の細い核を持ち細胞質が乏しい線維芽細胞(腱細胞)に混じって,核が楕円形で細胞質が豊富な線維芽細胞(腱芽細胞)が,3日後に少数出現し,1,2週後には増加したが,4週後以降は減少した.血管は,3日後には修復部の周辺に少数観察され,次第に増加して分布も広がり,2週後には修復部や切断された腱の内部にも多数観察されたが,4週後以降は減少した.修復部の線維芽細胞と膠原線維は,3日後には乏しかったが,1,2週後には増加し,4週後には多数が長軸に沿って配列して腱の断端と再生した腱との区別は困難だった.4週後以降には一部の再生腱で軟骨が見られ,3,6カ月後にはすべての再生腱で骨が観察された. 本実験で,アキレス腱の修復には腱内部と周囲結合組織の線維芽細胞が関わり,2週後に最も修復が盛んになることが示唆された.また,4週後ないし遅くとも6週後までに腱はおおむね修復されることが明らかになった.ラットとヒトでは異なるが,アキレス腱が高い修復能力を持ち比較的短期間に修復が進むことは,アキレス腱断裂に対する治療法を選択するうえで参考になり,リハビリテーションの開始時期を早めることができる可能性を示唆する.To investigate the regenerating ability and healing process of the rat Achilles tendon, the tendon was cut and its repair process was observed up to 6 months without hindlimb casting. The gap between severed tendons was filled with soft connective tissue at 3 days postoperatively and bridged by fibrous connective tissue at 1 week. By light microscopy, tendons showed a small number of tenoblasts with an ovoid nucleus and rich cytoplasm among tenocytes which contained a thin nucleus and scanty cytoplasm at 3 days. Tenoblasts increased in number at 1 and 2 weeks, and decreased at 4 weeks onward. Blood vessels were located at the peripheries of the regenerating portion at 3 days, increased in number and distribution throughout the regenerating portion and tendon at 2 weeks, and decreased at 4 weeks afterwards. Fibroblasts and collagen fibers at the regenerating portion were small in number at 3 days, increased at 1 and 2 weeks, and oriented along the long axis of tendon at 2 and 4 weeks. It was difficult to discriminate between severed tendon and the regenerated portion at 4 weeks. Cartilage was observed in some specimens at 4 weeks, and bones were found in all specimens at 3 and 6 months. These findings indicate that fibroblasts derived from both tendon and surrounding connective tissues are involved in repair, and that the repair process of tendon seems most active at 2 weeks after surgery. Regenerated tendons are considered to restore principal tendon structure at 4 or, at the latest, 6 weeks. Thus, Achilles tendon has an intrinsic ability to repair within several weeks, which provides a rationale for consideration of medical treatment and planning of early rehabilitation
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