A method to modify coordinates of detectors in positron emission tomography systems

A new method to modify coordinates of detectors in any positron emission tomography (PET) system using a radioactive point source is developed. This method is based on selecting a centered detector in each detector block of PET and measuring coincidence counts between the two centered detectors in opposite detector blocks to find the coordinates of their LOR (Line of Response). Due to slight misalignment of detector positions, measured LORs may not intersect at a single point. Based on the proposed method, the coordinates of detectors can be measured with very high accuracy and the coordinate of the center of the gantry (which is normally the same as the center of field of view) can be defined correctly. The results of the application of our method to a small animal PET system (FinePET), which was recently developed at Tohoku University, Japan, are shown here. The method is expected to contribute to the design and development of PET systems which can realize a very high spatial resolution of less than 1 mm FWHM.     

Single-Electron Device With Si Nanodot Array and Multiple Input Gates

We have developed a flexible-logic-gate single-electron device (SED) with an array of nanodots. Although the small size of SEDs is highly advantageous, the size of the nanodots inevitably fluctuates, which causes variations in device characteristics. This variability can be eliminated and high device functionality can be obtained by exploiting the oscillatory characteristics and multigate capability of SEDs. We fabricated, on a silicon-on-insulator wafer, a Si nanodot array device with two input gates and a control gate and investigated its basic operation characteristics experimentally. The device was demonstrated to operate as a logic gate providing six important logic functions ( and, or, nand, nor, xor, and xnor), which are obtained by adjusting the control-gate voltage.     

Sputtering of the aqueous solution of TiCI3 and the TiO2 formation

DC-plasma was generated between the substrate and the aqueous solution of TiCI₃ under the reduced pressure. Deposition was carried out for 1 h. The amount of the liquid loss and the morphology of the products were examined. A linear relationship existed between the liquid loss and the input power. The threshold power was 200 Watt, under which no stable discharge was established. The sputtering yield of H₂O molecules was between 100 and 900 at the applied voltages between 600 and 1300 V. TiO₂ thin films of microcrystalline rutile structure were deposited on the quartz glass substrates. On the titanium substrate, thick films of highly 110 oriented rutile structure were produced.     

Penalty function approach for the mixed discrete nonlinear problems by particle swarm optimization

In this paper, the basic characteristics of particle swarm optimization (PSO) for the global search are discussed at first, and then the PSO for the mixed discrete nonlinear problems (MDNLP) is suggested. The penalty function approach to handle the discrete design variables is employed, in which the discrete design variables are handled as the continuous ones by penalizing at the intervals. As a result, a useful method to determine the penalty parameter of penalty term for the discrete design variables is proposed. Through typical mathematical and structural optimization problems, the validity of the proposed approach for the MDNLP is examined.     

An Optimization Methodology for Neural Network Weights and Architectures

This paper introduces a methodology for neural network global optimization. The aim is the simultaneous optimization of multilayer perceptron (MLP) network weights and architectures, in order to generate topologies with few connections and high classification performance for any data sets. The approach combines the advantages of simulated annealing, tabu search and the backpropagation training algorithm in order to generate an automatic process for producing networks with high classification performance and low complexity. Experimental results obtained with four classification problems and one prediction problem has shown to be better than those obtained by the most commonly used optimization techniques     

Loss factors of mirrors for a gravitational wave antenna

Low-loss mirrors fabricated by ion-beam-sputtering machines for possible application in an interferometric gravitational wave antenna were evaluated by use of Nd:YAG laser light (lambda = 1064 nm) with two distinct measurements: a tabletop experiment that used a short cavity with a small beam with a beam waist of approximately 2w(0) = 0.82 mm, and an optical test that used a 20-m prototypical gravitational-wave detector with a large beam with a beam waist of approximately 2w(0) = 4.4 mm. A multilayer coating comprised 29 layers of SiO(2)/Ta(2)O(5) and one protective coating of SiO(2). The best values obtained as a result of these measurements were 16 ppm (parts in 10(6)) and 30 ppm in total loss, respectively. Also, a two-dimensional loss map generated by use of a small beam successfully revealed the existence of a loss structure within the coating surface. These results imply that a high-reflectance multilayer coating has some inhomogeneities and a loss distribution with a typical scale of a few millimeters and that the total measured losses depend on the beam spot size.     

Nucleotide sequencing analysis of the 146-kilobase segment around the IkBL and MICA genes at the centromeric end of the HLA class I region

The biomechanics of medialization laryngoplasty are not well understood. An excised canine larynx model was used to test the effects of various sized silicon implants. The vocal fold length, position, and tension were measured. Medialization laryngoplasty did not affect vocal fold length. At the mid-membranous vocal fold, larger shims resulted in greater medialization and tension. Medialization laryngoplasty neither medialized nor stiffened the vocal process to resist lateralizing forces. We conclude that medialization laryngoplasty provides bulk and support for defects of the membranous region of the vocal fold, but does not appear to close a posterior glottal gap. The selection of a surgical procedure to treat glottal incompetence should take into account the unique biomechanical properties of the anterior (membranous vocal folds) and posterior (cartilaginous portion) glottis.     

Sensitive diagnosis of cardiac allograft rejection by detection of cytokine transcription in situ

BACKGROUND & AIMS: Interleukin 12 (IL-12) is a heterodimeric, macrophage-derived cytokine that is elevated in Crohn's disease (CD). Epstein-Barr virus-induced gene 3 (EBI3) is a recently characterized human glycoprotein that is homologous to the 40-kilodalton chain of IL-12 and forms a heterodimer with the 35-kilodalton chain of IL-12. We investigated the expression of EBI3 in colonic mucosa of normal control subjects, patients with ulcerative colitis (UC), and patients with CD. METHODS: Colonic tissue was analyzed for messenger RNA (mRNA) expression by quantitative polymerase chain reaction and for protein expression by immunohistology and Western blotting. RESULTS: EBI3 mRNA was present in intestinal biopsy specimens from healthy subjects and patients with CD but was elevated only in active UC. EBI3 levels in UC specimens correlated with histological scores of activity and T-cell infiltration. EBI3-positive cells that had a shape consistent with that of macrophages were identified in the lamina propria, and protein was detected by Western blotting. CONCLUSIONS: EBI3 is a novel IL-12-related cytokine that is expressed by macrophage-like cells in normal intestine and CD and has enhanced expression in active UC but not in active CD.