158 research outputs found

    Toward Colloidal Motors

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    We have presented the first direct observation of electric field induced rotation of epoxy based polymer rotors. Polymer disks and gears were prepared in few micrometer dimensions as rotors. Electrorotation of these sub-millimeter sized tools was studied under uniform DC electric field. The rotational speed of micron-sized polymer rotors can be conveniently tuned in wide range (between 300 – 3000 rpm) by the DC electric field intensity, opening new perspectives for their use in micro electric motor applications

    Design and evaluation of a linear damper working with MR shear thickening fluids

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    Magnetorheological (MR) materials and shear thickening fluids are both smart material and their combination could offer both MR and ST effects. This study looks at the properties and behaviour of magnetorheological shear thickening fluid (MRSTF) in particular whilst applied as a semi-active energy absorber. A device with two forms of varying vibration control has been created and measured. The result shows that this MRSTF filled damper showed both MR and properties

    NScluster: An R Package for Maximum Palm Likelihood Estimation for Cluster Point Process Models Using OpenMP

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    NScluster is an R package used for simulation and parameter estimation for NeymanScott cluster point process models and their extensions. For parameter estimation, NScluster uses the maximum Palm likelihood estimation procedure. As some estimation procedures proposed herein require heavy calculation, NScluster can use parallel computation via OpenMP and achieve significant speedup in some cases. In this paper, we discuss results obtained using a laptop PC and a shared memory supercomputer. In addition, we examine the performance characteristics of parallel computation via OpenMP

    Survey of above knee (A/K) prostheses currently used in the Chugoku-Shikoku district of Japan

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    To determine the extent to which recent advances in biomechanical technology have been implemented and to evaluate these new technologies, 84 unilateral above knee (A/K) amputees and their prostheses were surveyed in the Chugoku-Shikoku district of Japan, especially in regard to the types, sockets and components of A/K prostheses currently in use. Background factors such as age and sex of the A/K amputees and the period after amputation were also surveyed. Of the 84 amputees surveyed, 74 (88.1%) were over 40 years old and 40 (47.6%) were over 60 years old. There were 10 women (11.9%) and 74 men (88.1%). The period after amputation was under 25 years in 58 (69.0%) cases. Regarding the type of A/K prostheses, one-third of the prostheses was of the exoskeletal type and two-thirds were of the endoskeletal type. Although the endoskeletal type is becoming more popular recently, elderly A/K amputees tend to use the exoskeletal type. Thirty-one (36.9%) had plug-fit sockets which are preferable for those who follow the Japanese practice of sitting on the floor, especially for elderly amputees. Thirty-seven (44.0%) had a lock-knee, 27 (73.0%) of which were used by amputees over 60 years old. Seventy-three (86.9%) had a single-axis ankle which is generally considered to be the most stable ankle. Thus, the most common combination of prosthetic components for elderly A/K amputees was the plug-fit socket, lock-knee joint and single-axis ankle.</p

    Development of magnetorheological elastomers-based tuned mass damper for building protection from seismic events

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    This study investigated and evaluated a semi-active tuned mass damper which incorporated four multi-layered structures fabricated using magnetorheological elastomers. The four magnetorheological elastomer structures formed a square and provided the tuned mass damper variable stiffness used to track the excitation frequencies. This design not only increases the stability of the tuned mass damper but more importantly eliminates the magnetic circuit gap in a design which we used in the past because all four of the magnetic circuits used to control the magnetorheological elastomer isolators are closed circuits. In order to verify the capability of the magnetorheological elastomer-based tuned mass damper to protect a building from earthquake, extensive simulation and experimental testing were conducted. The swept sinusoidal signal and the scaled 1940 El Centro earthquake record were used to excite a scaled three-story building. Both simulation and experiment have verified that the magnetorheological elastomer-based tuned mass damper outperformed all other passive tuned mass dampers under either swept sinusoidal or seismic conditions

    Dysphagia Screening Questionnaire : Swallow-10

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    The Seirei dysphagia screening questionnaire (namely, Seirei dsq) has been used to screen for oropharyngeal dysphagia (OD). Some of the questions in the questionnaire are difficult for people with cognitive decline to answer. We selected 10 items from the Seirei dsq that could be assessed by others, such as care workers (named Swallow-10). This study aims to verify the validity of the scoring method used in Swallow-10. The dataset used in this study was the one used in the development of Seirei dsq : 50 patients with cerebrovascular disease who were diagnosed with OD, 145 patients with cerebrovascular disease who did not have OD, and 170 healthy subjects. Among the answer choices, “A” for severe symptom, “B” for mild symptom and “C” for no symptom were scored with 4, 1 and 0 points respectively. Factor analysis extracted two factors : one related to pharyngeal function and another related to oral function. In addition, the Cronbach’s alpha coefficient was 0.84. ROC analysis indicated that optimal cutoff value was 5 points, with a sensitivity of 90.0% and a specificity of 88.5%. These results suggest that Swallow-10 may be useful as an OD screening tool for subjects with cognitive decline

    EFFICACY OF INTERFERON THERAPY FOR CHRONIC HEPATITIS C : A COOPERATIVE STUDY IN ELEVEN HOSPITALS

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    We investigated the influences of liver histology,serum levels of hepatitis C virus (HCV) and HCV genotypes on responsiveness to interferon (IFN) therapy in 342 patients with chronic hepatitis C. Either 9 million units (MU) of lymphoblastoid alpha IFN or 3 MU of recombinant IFN-alpha was administered daily for 2 weeks and then three times a week for 22 weeks. IFN responses were divided into three groups on the basis of the results of polymerase chain reaction (PCR) assay detecting HCV-RNA in serum. Complete response (CR) was defined as sustained elimination of HCV for at least 6 months after treatment,partial response (PR) as HCV elimination for a limited period,non-response (NR) as continuously positive for HCV-RNA in serum. Quantitation of pre-treament HCV-RNA amount in serum was determined by competitive PCR assay in 47 patients. HCV genotyping was performed in 114 patients by PCR with genotype-specific primers. CR was obtained in 97 patients (28.4%),PR in 104 (30.4%) and NR in 141 (41.2%). IFN responses,represented by CR/PR/NR,were 15/18/11 in 44 patients with chronic persistent hepatitis (CPH),72/65/73 in 210 patients with chronic aggressive hepatitis (CAH) 2a,and 10/21/57 in 88 patients with CAH2b. CR rate was lower in patients with CAH2b (11.4%) compared to those with CPH (34.1%) or CAH2a (34.3%). Averages of pre-treatment serum HCV-RNA amount (copies/50μl) were 10³·⁵⁵ in 13 CRs,10⁴·⁵⁶ in 17 PRs,and 10⁵·⁹⁵ in 17 NRs. There was a positive correlation between pre-treatment HCV-RNA levels and IFN unresponsiveness. HCV genotyping in 114 patients revealed that HCV type Ⅰ infection was observed in one,type Ⅱ in 94,type Ⅲ in 11,type Ⅳ in 6 and mixed (types Ⅱ and Ⅳ) in 2 patients,and their IFN responses (CR/PR/NR) were 0/0/1,28/26/40,3/5/3,1/3/2 and 0/1/1,respectively
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