A Design Method for Pin Holding Type Jig

Multi-item flexible manufacturing systems have been spread to correspond the short life-cycle and the diversification of products. Part handling plays an important role to operate multi-functional robot efficiently in these systems, and many jigs are widely used to hold a part. They should be exchanged at once according to changing products. In this paper, we propose a pin jig which holds a part with two pins, and design method of the position, length and diameter of those pins for a cylindrical part. This jig has the following characteristics. As a surface of the jig is inclined to use gravity, the part can be fixed without any external forces. Therefore the structure of jig becomes simple, and loading and unloading of a part becomes easy for a robot hand

加温後のtsAF8細胞の細胞周期

Thermotolerance in tsAF8 cells develops during incubation at 34℃ after heating at 45℃, while it is suppressed by the following incubation at a non-permissive temperature of 39.7℃ after the same heating. The incubation temperature after heating may affect the cell cycle and consequently thermotolerance. In the present study, a relationship between the thermotolerance and the cell cycle of tsAF8 was investigated. The cell cycle fractions and DNA synthesis were measured by flow cytometry using double staining with propidium iodide and bromodeoxyuridine. When the tsAF8 cells were heated at 45℃ for 20 min, and thereafter incubated at 34℃, bromodeoxyuridine uptake in the S phase cells (DNA synthesis) was recovered to 65.1% 6 h after the heating, and the cells showed gradual accumulation in the G(2)/M phase. When the cells were incubated at 39.7℃ after heating at 45℃ for 20 min, then showed inhibition of thermotolerance development, the DNA synthesis was recovered to 15.1% temporarily 6 h after the heating, but it became 0% after 12 h, and the cells did not remarkably accumulate in any phases of the cell cycle. This inhibition of DNA synthesis at 39.7℃ was considered to be the result of cell survival decreasing by a step-down heating. However, the relationship between the thermotolerance and the cell cycle was not found out in tsAF8 cells, because the cells did not accumulate in any phases of the cell cycle under the inhibitory condition of thermotolerance.tsAF8細胞は45℃の加温後34℃で培養すると温熱耐性が速やかに発現するが,加温後,制限温度である39.7℃で培養すると温熱耐性の発現が抑制される｡加温後の培養温度が細胞周期に影響し,その結果として温熱耐性発現に影響を与えている可能性があることから,今回,Propidium Iodide(PI)とbromodeoxyuridine(BrdU)でtsAF8細胞を二重染色し,フローサイトメトリーによって温熱耐性と細胞周期の関係の有無について調べた｡tsAF8細胞を45℃20分の加温後34℃で培養すると,6時間後にはG(1)期の細胞が減少し,12時間後にはG(2)/M期への蓄積が見られた｡しかし,加温後39.7℃で培養した場合には細胞周期の進行がほとんど見られなかった｡BrdU の取込みは,加温せずに39.7℃で培養した場合には活発に行われ,また,45℃20分加温後34℃で培養した場合には,6時間後にはBrdUの取り込みは65.1%まで回復した｡しかし,温熱耐性発現の抑制が観察される45℃20分加温後39.7℃で培養した場合には,BrdUの取込み量は6時間後に一時的に15.1%に回復するが,12時間後には取込み量はゼロとなった｡BrdUの取り込みが阻害されたのはstep-down heatingの現象による細胞生存率の減少が原因だと考えられたが,温熱耐性発現の抑制が観察される条件下では細胞周期の特定の時期への集積がなかったことから,温熱耐性と細胞周期との関係はtsAF8細胞においては見い出されなかった

Preface

No Abstract.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/77506/1/1700_ftp.pd

Visualization of Stent Lumen in MR Imaging: Relationship with Stent Design and RF Direction

Magnetic resonance imaging (MRI) visualization of metallic stent lumens is possible if the stent structure counteracts eddy currents in the lumen induced by the radio frequency magnetic field, B1. To examine the effectiveness of various stent designs in counteracting eddy currents, we anchored eight copper stent models and 2 commercially available nickel-titanium alloy (Nitinol) stents in a gel phantom, perpendicular or parallel to the direction of B1. A mesh stent lumen showed hypointensity irrespective of its alignment relative to B1. A solenoid stent lumen showed hypointensity with the stent axis parallel to B1, but it had the same signal intensity as outside the lumen when perpendicular to B1. A Moebius stent lumen showed no signal reduction, irrespective of alignment relative to B1. Lumens of the commercially available stents showed hypointensity regardless of alignment relative to B1. Computer simulation revealed that the signal intensities of the stents corresponded to magnetic flux densities of B1 in the stents, which are modified by the structure of the stent. While in vivo MRI viewing of a Moebius stent lumen is likely possible regardless of axis alignment, inherent structural weakness may be problematic. As a more practical choice, the solenoid stent is easier to manufacture and generates no hypointensive signal when the axis is parallel to B0

A Study of Reconstruction of Magnetic Resonance Image

磁気共鳴は医学におけるイメージングにおいて重要なモダリティーであり,高度な数学的手法が画像の再構成に取り入れられている｡画像再構成の数学的手法および画像再構成にいたるまでの数学的な過程を理解するこは,MRIを学ぶものにとって非常に重要であるが,成書において明確な説明はなされていない｡ここでは,MR画像の再構成法を,複素関数と複素フ-リェ係数を用いて導いたので報告する｡Magnetic resonance is an important modality for medical imaging, and advanced mathematical techniques are introduced into the reconstruction of images. Clearly understandable explanations of the reconstruction of the MR image and of the mathematical derivation process have not been presented in the texts. Reconstruction of MR image is presented using the complex function and its relevant Fourier coefficients

In Vitro Assessment of Factors Affecting the Apparent Diffusion Coefficient of Ramos Cells Using Bio-phantoms

The roles of cell density, extracellular space, intracellular factors, and apoptosis induced by the molecularly targeted drug rituximab on the apparent diffusion coefficient (ADC) values were investigated using bio-phantoms. In these bio-phantoms, Ramos cells (a human Burkittｾs lymphoma cell line) were encapsulated in gellan gum. The ADC values decreased linearly with the increase in cell density, and declined steeply when the extracellular space became less than 4 μm. The analysis of ADC values after destruction of the cellular membrane by sonication indicated that approximately 65% of the ADC values of normal cells originate from the cell structures made of membranes and that the remaining 35% originate from intracellular components. Microparticles, defined as particles smaller than the normal cells, increased in number after rituximab treatments, migrated to the extracellular space and significantly decreased the ADC values of bio-phantoms during apoptosis. An in vitro study using bio-phantoms was conducted to quantitatively clarify the roles of cellular factors and of extracellular space in determining the ADC values yielded by tumor cells and the mechanism by which apoptosis changes those values

A lost mathematician, Takeo Nakasawa : the forgotten father of matroid theory

Matroid theory was invented in the middle of the 1930s by two mathematicians independently, namely, Hassler Whitney in the USA and Takeo Nakasawa in Japan. Whitney became famous, but Nakasawa remained anonymous until two decades ago. He left only four papers to the mathematical community, all of them written in the middle of the 1930s. It was a bad time to have lived in a country that had become as eccentric as possible. Just as Nazism became more and more flamboyant in Europe in the 1930s, Japan became more and more esoteric and fanatical in the same time period. This book explains the little that is known about Nakasawa’s personal life in a Japan that had, among other failures, lost control over its military. We do not know what forces caused him to be discharged from the Tokyo University of Arts and Sciences. His work was considered brilliant, his papers superb, if somewhat unconventional and mysterious in notation. We do know that, in the latter half of the 1930s, forced to give up his mathematical career, he chose to live as a bureaucrat in Manchuria, at that time a puppet state of Japan. He died in 1946 at Khavarovsk, at the age of 33, after one year of forced labor in Siberian and other USSR camps, without sufficient food or shelter to protect his health. This book contains his four papers in German and their English translations as well as some extended commentary on the history of Japan during those years. The book also contains 14 photos of him or his family. Although the veil of mystery surrounding Nakasawa’s life has only been partially lifted, the work presented in this book speaks eloquently of a tragic loss to the mathematical community.As to Chapter2-5, only the first page is free to ope

Observation of a Highly Spin Polarized Topological Surface State in GeBi2_{2}Te4_{4}

Spin polarization of a topological surface state for GeBi$_2$Te$_4$, the newly discovered three-dimensional topological insulator, has been studied by means of the state of the art spin- and angle-resolved photoemission spectroscopy. It has been revealed that the disorder in the crystal has a minor effect on the surface state spin polarization and it exceeds 75% near the Dirac point in the bulk energy gap region ($\sim$180 meV). This new finding for GeBi$_{2}$Te$_{4}$ promises not only to realize a highly spin polarized surface isolated transport but to add new functionality to its thermoelectric and thermomagnetic properties.Comment: 5 pages, 4 figure

Measurement of sampling time in MRI and reconstruction of MR image

MRIにおいてk-spaceを構築するためにはエコー信号をサンプリング時間に従って採取する必要がある.このサンプリング時間を測定するために,FOV(field of view)の左半分にファントムを置くことにより階段関数となるスピン分布を生成した｡得られたエコー信号を,階段関数をフ-リェ変換したときに得られるフ-リェ係数と比較することによりサンプリング時間を求めた｡得られたサンプリング時間を用いて,MRI MULTI-TEST PHANTOMをMRI装置でスキャンすることにより得られたエコー信号をサンプリングしk-spaceを構築した。このk-spaceをフ-リェ逆変換することによりMRI MULTI-TEST PHANTOMの画像を再構成することができた。Regarding the construction of k-space in MRI, it is necessary to extract the required data from the echo signals with the rate of sampling time. In order to measure the sampling time, a rectangular phantom was placed on the left side of the FOV in the body coil of an MRI equipment, and got analog signals in the sequence of spin echo. The sampling time was determined by comparing the measured signals with the Fourier coefficients obtained by transforming the step function which was similar to the profile of the FOV. The MRI MULTI-TEST PHANTOM was scanned, and the k-space was constructed with the extracted data from the echo signals with the rate of the determined sampling time. The MRI images of the MULTI-TEST PHANTOM were reconstructed by inverse-transforming the obtained k-space