A secure communication network with quantum key distribution in a metropolitan area is reported. Six different QKD systems are integrated into a mesh-type network. GHz-clocked QKD links enable us to ...demonstrate the world-first secure TV conferencing over a distance of 45km. The network includes a commercial QKD product for long-term stable operation, and application interface to secure mobile phones. Detection of an eavesdropper, rerouting into a secure path, and key relay via trusted nodes are demonstrated in this network.
Background. A well-functioning vascular access (VA) is essential to efficient dialysis therapy. Guidelines have been implemented improving care, yet access use varies widely across countries and VA ...complications remain a problem. This study took advantage of the unique opportunity to utilize data from the Dialysis Outcomes and Practice Patterns Study (DOPPS) to examine international trends in VA use and trends in patient characteristics and practices associated with VA use from 1996 to 2007. DOPPS is a prospective, observational study of haemodialysis (HD) practices and patient outcomes at >300 HD units from 12 countries and has collected data thus far from >35 000 randomly selected patients. Methods. VA data were collected for each patient at study entry (1996–2007). Practice pattern data from the facility medical director, nurse manager and VA surgeon were also analysed. Results. Since 2005, a native arteriovenous fistula (AVF) was used by 67–91% of prevalent patients in Japan, Italy, Germany, France, Spain, the UK, Australia and New Zealand, and 50–59% in Belgium, Sweden and Canada. From 1996 to 2007, AVF use rose from 24% to 47% in the USA but declined in Italy, Germany and Spain. Moreover, graft use fell by 50% in the USA from 58% use in 1996 to 28% by 2007. Across three phases of data collection, patients consistently were less likely to use an AVF versus other VA types if female, of older age, having greater body mass index, diabetes, peripheral vascular disease or recurrent cellulitis/gangrene. In addition, countries with a greater prevalence of diabetes in HD patients had a significantly lower percentage of patients using an AVF. Despite poorer outcomes for central vein catheters, catheter use rose 1.5- to 3-fold among prevalent patients in many countries from 1996 to 2007, even among non-diabetic patients 18–70 years old. Furthermore, 58–73% of patients new to end-stage renal disease (ESRD) used a catheter for the initiation of HD in five countries despite 60–79% of patients having been seen by a nephrologist >4 months prior to ESRD. Patients were significantly (P < 0.05) less likely to start dialysis with a permanent VA if treated in a faciity that (1) had a longer time from referral to access surgery evaluation or from evaluation to access creation and (2) had longer time from access creation until first AVF cannulation. The median time from referral until access creation varied from 5–6 days in Italy, Japan and Germany to 40–43 days in the UK and Canada. Compared to patients using an AVF, patients with a catheter displayed significantly lower mean Kt/V levels. Conclusions. Most countries meet the contemporary National Kidney Foundation's Kidney Disease Outcomes Quality Initiative goal for AVF use; however, there is still a wide variation in VA preference. Delays between the creation and cannulation must be improved to enhance the chances of a future permanent VA. Native arteriovenous fistula is the VA of choice ensuring dialysis adequacy and better patient outcomes. Graft is, however, a better alternative than catheter for patients where the creation of an attempted AVF failed or could not be created for different reasons.
Cementum was first demonstrated by microscopy, about 180 years ago. Since then the biology of cementum has been investigated by the most advanced techniques and equipment at that time in various ...fields of dental sciences. A great deal of data on cementum histology have been accumulated. These data have been obtained from not only human, but also non-human animals, in particular, rodents such as the mouse and rat. Although many dental histologists have reviewed histology of human cementum, some descriptions are questionable, probably due to incorrect comparison of human and rodent cementum. This review was designed to introduce current histology of human cementum, i.e. its structure, function, and development and to re-examine the most questionable and controversial conclusions made in previous reports.
Timing-performance evaluation of Cherenkov-based radiation detectors Ota, R.; Nakajima, K.; Hasegawa, T. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
04/2019, Letnik:
923
Journal Article
Recenzirano
Odprti dostop
With the upgradation of detector components, such as scintillators and photodetectors, the PET-image signal-to-noise ratio of time-of-flight positron emission tomography (TOF-PET) systems has been ...improved, compared to those of ordinary nonTOF-PET systems. A TOF-PET with an ultrahigh time resolution, for example a coincidence time resolution (CTR) better than few tens of picoseconds, can not only improve the image quality, but also remove the image reconstruction process, significantly impacting medical imaging. Therefore, it is crucial to develop a high-time resolution PET detector. We focus on the prompt emission of Cherenkov radiation, owing to the instantaneousness of which, a high time resolution can be expected. One of the candidates for the Cherenkov radiator is lead fluoride (PbF2) due it has excellent properties, including transparency toward the ultraviolet region, high refractive index (n = 1.82), and high density (7.77 g/cm3). Moreover, it does not contain radioisotopes, unlike lutetium-based scintillators, which are commonly used in the currently available TOF-PET detectors. In this work, we experimentally investigate the timing performance of PbF2-based Cherenkov detectors, breaking down the timing performance into physical components. 3×3×5 mm3 and 9.6×9.6×5 mm3 PbF2 crystals are used as Cherenkov radiators; both are attached to a microchannel plate photomultiplier tube (MCP-PMT) because the single channel MCP-PMT is one of the best photodetectors in terms of the SPTR, which is 25 ps full width at half maximum (FWHM). All the surfaces, except the end surface where the MCP-PMT is connected, are wrapped in black tape to suppress the reflections of the Cherenkov photons in the crystal. The CTR is measured by placing a detector pair face-to-face, using an 22Na point source, and an oscilloscope at 20 GS/s with a set bandwidth of 4.2 GHz. A CTR of 46.9 ps FWHM, corresponding to a position resolution of 7.0 mm, is obtained, consistent with our simulation results.
Good barriers make good languages. Scholars have long speculated that geographical barriers impede linguistic contact between speech communities and promote language diversification in a manner ...similar to the process of allopatric speciation. This hypothesis, however, has seldom been tested systematically and quantitatively. Here, we adopt methods from evolutionary biology and attempt to quantify the influence of oceanic barriers on the degree of lexical diversity in the Japanese Islands. Measuring the degree of beta diversity from basic vocabularies, we find that geographical proximity and, more importantly, isolation by surrounding ocean, independently explains a significant proportion of lexical variation across Japonic languages. Further analyses indicate that our results are neither a by‐product of using a distance matrix derived from a Bayesian language phylogeny nor an epiphenomenon of accelerated evolutionary rates in languages spoken by small communities. Moreover, we find that the effect of oceanic barriers is reproducible with the Ainu languages, indicating that our analytic approach as well as the results can be generalized beyond Japonic language family. The findings we report here are the first quantitative evidence that physical barriers formed by ocean can influence language diversification and points to an intriguing common mechanism between linguistic and biological evolution.
Transparent conducting TiO2, obtained by Nb or Ta doping of the anatase structure, is gaining increasing attention for the development of transparent electrodes. Usually, regardless of the deposition ...technique, a crystallization process in a reducing atmosphere is necessary to achieve large mobility; in addition, electrical and optical properties are also strongly sensitive to the oxygen deposition pressure. These facts reveal that the defect chemistry of donor-doped TiO2 is not trivial and involves a strict interplay among extrinsic dopant atoms, oxygen vacancies, and “electron killer” defects such as Ti vacancies and O interstitials. We here present a Raman characterization of donor-doped TiO2 films synthesized under several deposition and postannealing conditions, employing different doping levels and dopant elements (i.e., Ta and Nb). Correlations between structure, crystallinity, shift and width of Raman peaks, and electrical properties are shown and discussed. In particular, a clear relationship between the shift of the Eg(1) anatase Raman mode and the charge carrier density is found, while the B1g(1) mode connected to Ti–Ti vibrations is significantly affected by the extrinsic doping level. In this complex framework, Raman spectroscopy can provide an invaluable contribution toward understanding the material structure and its influence on the functional properties.
Micro X-ray fluorescence (micro-XRF) analysis is repeated as a means of producing elemental maps. In some cases, however, the XRF images of trace elements that are obtained are not clear due to high ...background intensity. To solve this problem, we applied principal component analysis (PCA) to XRF spectra. We focused on improving the quality of XRF images by applying PCA. XRF images of the dried residue of standard solution on the glass substrate were taken. The XRF intensities for the dried residue were analyzed before and after PCA. Standard deviations of XRF intensities in the PCA-filtered images were improved, leading to clear contrast of the images. This improvement of the XRF images was effective in cases where the XRF intensity was weak.
It has been observed to appear a step-wise or duplex
S–
N curve under the test of rotary bending fatigue using high strength steel. This behavior was caused by the transition of fracture mode from ...surface-induced fracture to subsurface inclusion-induced fracture. The aim of this study is to clarify the
S–
N characteristic under an axial loading fatigue in the very high cycle fatigue regime. In order to investigate the mean-stress effects, fatigue tests were carried out in air at room temperature under three applied stress ratios of −1, 0 and 0.5 using a hour-glass shaped specimen of high carbon–chromium bearing steel, JIS SUJ2. From the results, three types of fracture mode were observed on the fracture surface, such as surface-induced fracture, subsurface inclusion-induced fracture without granular bright facet (GBF) area and that with GBF area around an inclusion. Fatigue lifetime for transition in the fracture mode depended on the applied stress ratio. Shape of the
S–
N curve was a smooth and continuous under three testing conditions in spite of the occurrence on the three types of fracture. Detail discussion for fatigue fracture behavior was made through the observation of fracture surface and from point in view of the fracture mechanics. In addition, an effect of residual stress in the specimen surface layer on the transition of fracture mode was discussed and compared with the experimental results.
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