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Search Results: 1 - 10 of 2768 matches for " Masahiro Nakajima "
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Dual-Energy Subtraction X-Ray Digital Tomosynthesis: Basic Physical Evaluation  [PDF]
Tsutomu Gomi, Masahiro Nakajima
Open Journal of Medical Imaging (OJMI) , 2012, DOI: 10.4236/ojmi.2012.23021
Abstract: The present study was performed to determine the potential of applying dual-energy subtraction (DES) digital tomo-synthesis to basic physical evaluations. Volumetric X-ray DES digital tomosysnthesis was used to obtain an image of a detectability phantom (an artificial lesion). The image quality of DES digital tomosynthesis was compared to that of DES radiography. The purpose of this study was to determine enhanced visibility quantified in terms of the contrast- to-noise ratio, figure-of-merit, and root-mean-square error. In the in-focus plane, the image quality is better by DES digital tomosynthesis than by DES radiography. The potential usefulness of DES digital tomosynthesis for evaluating a detectability phantom was demonstrated. Further studies are required to determine the ability of DES digital tomosyn-thesis to quantify the spatial relationships between the artificial lesion components of these devices, as well as to iden- tify lesions with diagnostic consequences.
X-ray digital linear tomosynthesis imaging  [PDF]
Tsutomu Gomi, Hiroshi Hirano, Masahiro Nakajima, Tokuo Umeda
Journal of Biomedical Science and Engineering (JBiSE) , 2011, DOI: 10.4236/jbise.2011.46056
Abstract: Aims: The purpose of this review includes the fol-lowing: 1) to identify indications for volumetric X-ray digital linear tomosynthesis by using a filtered back projection (FBP) algorithm and 2) to compare X-ray digital linear tomosynthesis, X-ray digital ra-diography, conventional tomography, and computed tomography. Review: The methods include the fol-lowing: 1) an overview of the tomosynthesis system in comparison with conventional X-ray imaging tech-nology; 2) an overview of the properties of diagnostic imaging for the chest, hip joint, and temporomandibular joint when imaging overlying structures and their effect of various artificial images; and 3) a review of each system. Summary: Tomosynthesis is worthy of further evaluation because of its flexibility and ability to suppress streak artifacts through an appropriate choice of an FBP algorithm. Tomosynthesis may be considered the imaging technique of choice for investigation of bone changes and detection of pulmonary nodules. Understanding the potential of tomosynthesis imaging will improve diagnostic accuracy in clinical applications.
Tungsten/Platinum Hybrid Nanowire Growth via Field Emission Using Nanorobotic Manipulation
Zhan Yang,Masahiro Nakajima,Yasuhito Ode,Toshio Fukuda
Journal of Nanotechnology , 2011, DOI: 10.1155/2011/386582
Abstract: This paper reports tungsten-platinum hybrid nanowire growth via field emission, based on nanorobotic manipulation within a field emission scanning electron microscope (FESEM). A multiwalled carbon nanotube (MWCNT) was used as the emitter, and a tungsten probe was used as the anode at the counterposition, by way of nanomanipulation. By independently employing trimethylcyclopentadienyl platinum (CpPtMe3) and tungsten hexacarbonyl (W(CO)6) as precursors, the platinum nanowire grew on the tip of the MWCNT emitter. Tungsten nanowires then grew on the tip of the platinum nanowire. The hybrid nanowire length wascontrolled by nanomanipulation. Their purity was evaluated using energy-dispersive X-ray spectroscopy (EDS). Thus, it is possible to fabricate various metallic hybrid nanowires by changing the precursor materials. Hybrid nanowires have various applications in nanoelectronics, nanosensor devices, and nanomechanical systems. 1. Introduction Nanoelectronic and nanoelectromechanical (NEMS) devices have been widely investigated in recent years. Precise and controllable nanofabrication methods are important for developing novel nanodevices. Nanowires are candidates for use as nanodevices components, because of their unique and attractive physical and chemical properties. Various one-dimensional nanostructures, such as metallic nanowires [1], carbon nanotubes [2], and semiconducting nanowires [3], have been reported. Numerous metallic nanowires have been synthesized from porous membranes [4–6], organic nanotube templates [7], surface step edge [8] and biotemplate methods [9]. Electron-beam-induced deposition (EBID) [10] and ion-beam-induced deposition (IBID) [11] are important techniques for single metal nanowire growth [12]. These methods employ electron or ion beams which are focused on a substrate, in a low pressure gas chamber containing the precursors. Precursor molecules contain the elements to be deposited upon dissociation, with heavy parts of the molecule being fixed on the solid substrate and volatile parts being evacuated. The field emission technique is also an effective way to grow single nanowires, and is based on the decomposition of precursor gas molecules by the field emission current. Oon et al. reported metallic nanowire growth [13, 14] via field emission. Field emission refers to the emission of electrons from the surface of a condensed phase under a strong electric field [15]. Molecules decompose into positive and negative ions, and positive ions are attracted to the cathode and constructed to form nanostructures. Liu et al. demonstrated
Characterization of β-N-acetylhexosaminidase (LeHex20A), a member of glycoside hydrolase family 20, from Lentinula edodes shiitake mushroom)
Naotake Konno, Hideyuki Takahashi, Masahiro Nakajima, Takumi Takeda, Yuichi Sakamoto
AMB Express , 2012, DOI: 10.1186/2191-0855-2-29
Abstract:
Description of eta-distributions at RHIC energies in terms of the Ornstein-Uhlenbeck process and relativistic diffusion equations
Minoru Biyajima,Masahiro Kaneyama,Takuya Mizoguchi,Noriaki Nakajima
Physics , 2004,
Abstract: Assuming the Ornstein-Uhlenbeck process and relativistic diffusion equations with three sources at y = 0, we analyze eta-distributions of d+Au collision as well as Au+Au collisions at sqrt{s_{NN}} = 130 GeV and 200 GeV.
The effectiveness of local anesthetic and sodium hyaluronate injection for the posterior disc displacement: A case report  [PDF]
Yui Mori, Kenji Kakudo, Hideya Haeniwa, Motohiro Gotoh, Hirohito Kubo, Yuichi Ohnishi, Masahiro Nakajima, Harumi Iwasaki, Hironori Akiyama, Yoritaka Yotsui, Kimishige Shimizutani
Open Journal of Stomatology (OJST) , 2013, DOI: 10.4236/ojst.2013.33038
Abstract:

Posterior disc displacement of the temporomandibular joint is rare. We present a unique treatment method and magnetic resonance (MR) images of this condition. The patient was a 43-year-old male with a chief complaint of abnormal occlusion. Regarding the present status, there was no occlusion on the right side. No temporomandibular joint pain, myalgia, or clicking were observed while mouth opening. On MR images, the posterior disc displacement without reduction on the right was observed and it was assumed that occlusal abnormality was due to this condition. We treated him with the following methods. After injection into the superior articular cavity with 2% lidocaine, a sodium hyaluronate preparation was injected followed by intermaxillary traction applied using rubber. The recovery of occlusion was confirmed in follow-up at 5 days after treatment. In the 13th days, the intermaxillary traction was removed. On MR images, the right disc condition was changed to anterior disc displacement with reduction. We consider our treatment methods are effective for this clinical condition.

Remarks on the Erroneous Dispersion Surfaces From a Pair of a Hyperbolic Branch and An Elliptical Arc of the Intersected Two Laue Spheres Based on the Usual Crude Approximation  [PDF]
Tetsuo Nakajima
Journal of Modern Physics (JMP) , 2011, DOI: 10.4236/jmp.2011.23022
Abstract: In almost all previous works, the hyperbolic dispersion surfaces of the central proper quadrics have been crudely derived from the degree of reduction from the bi-quadratic equation by use of some roughly indefinable approximate relations. Moreover, neglecting the high symmetry of the hyperbola, both the branches have been approximated on the asymmetric surfaces composed of a pair of a branch of the hyperbola and a vertex of the ellipse without the presentation of reasonable evidence. Based upon the same dispersion surfaces equation, a new original gapless dispersion surfaces could be rigorously introduced without crude omission of even a term in the bi-quadratic equation based upon usual analogy with the extended band theory of solid as the close approximation to the truth.
Migration, Employment, and Industrial Development in Japan  [PDF]
Tetsuya Nakajima
Theoretical Economics Letters (TEL) , 2014, DOI: 10.4236/tel.2014.48083
Abstract: Industrial development in Japan is accompanied by massive migration from agricultural to industrial areas. In a modified Harrod-Domar model, this paper compares two steady states, the first and the second, which emerge before and after the termination of such migration, respectively. Then, the paper shows that employment rates must be lower in the second steady state. Further, by examining the effects of fiscal policy, the paper shows that the balanced budget multiplier exceeds unity, and fiscal policy raises households’ disposable income and consumption.
Mechanical, Thermal and Electrical Properties of Lotus-Type Porous Metals  [PDF]
Hideo Nakajima
Materials Sciences and Applications (MSA) , 2018, DOI: 10.4236/msa.2018.92017
Abstract: Lotus-type porous metals are fabricated by directional solidification of molten metals dissolving hydrogen. Unidirectional pores cause various anisotropic features of mechanical, thermal and electrical properties. Tensile, compressive and fatigue strength parallel to the pore direction are higher than those perpendicular to the pore direction. Besides, thermal and electrical conductivities parallel to the pore direction are higher than those perpendicular to the pore direction. Such anisotropy is attributed to the difference in the pinning cross-sectional area due to the dislocations and the scattering cross-sectional area due to electrons. The pore cross-sectional area perpendicular to the pore direction is much larger than that parallel to the pore direction. It is surmised that such difference in pore cross-section results in the anisotropy in mechanical, thermal and electrical properties.
Prediction model for knee osteoarthritis based on genetic and clinical information
Hiroshi Takahashi, Masahiro Nakajima, Kouichi Ozaki, Toshihiro Tanaka, Naoyuki Kamatani, Shiro Ikegawa
Arthritis Research & Therapy , 2010, DOI: 10.1186/ar3157
Abstract: We genotyped risk alleles of the three susceptibility genes, asporin (ASPN), growth differentiation factor 5 (GDF5), and double von Willebrand factor A domains (DVWA) for a total of 2,158 Japanese subjects (933 OA and 1,225 controls) and statistically analyzed their effects. After that, we constructed prediction models by using the logistic regression analysis.When the effects of each allele were assumed to be the same and multiplicative, each additional risk allele increased the odds ratio (OR) by a factor of 1.23 (95% confidence interval (CI), 1.12 to 1.34). Individuals with five or six risk alleles showed significantly higher susceptibility when compared with those with zero or one, with an OR of 2.67 (95% CI, 1.46 to 4.87; P = 0.0020). Statistical evaluation of the prediction power of models showed that a model using only genotyping data had poor predictability. We obtained a model with good predictability by incorporating clinical data, which was further improved by rigorous age adjustment.Our results showed that consideration of adjusted clinical information, as well as increases in the number of risk alleles to be integrated, is critical for OA prediction by using data from case-control studies. To the authors' knowledge, this is the first report of the OA-prediction model combining both genetic and clinical information.Osteoarthritis (OA) is the most common bone and joint disease and is characterized by progressive cartilage degeneration. OA is a polygenic disease caused by genetic and environmental factors [1]. Epidemiologic studies have suggested that genetic factors strongly affect the onset and development of OA [2]. Genetic association studies are now uncovering the genetic factors responsible for of OA, that is, its susceptibility genes. Candidate-gene approaches have identified several genes associated with OA, and genome-wide association studies have recently found several promising OA-susceptibility genes [1,3].Identification of OA-susceptibility ge
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