Discharge characteristics of steady-state high-density plasma source based on cascade arc discharge with hollow cathode.

We developed a steady-state high-density plasma source by applying a hollow cathode to a cascade arc discharge device. The hollow cathode is made of a thermionic material (LaB6) to facilitate plasma production inside it. The cascade arc discharge device with the hollow cathode produced a stationary plasma with an electron density of about 1016 cm-3. It was found that the plasma source produces a strong pressure gradient between the gas feed and the vacuum chamber. The plasma source separated the atmospheric pressure (100 kPa) and a vacuum (100 Pa) when the discharge was performed with an argon gas flow rate of 5.0 l/min and a discharge current of 40 A. An analysis of the pressure gradient along the plasma source showed that the pressure difference between the gas feed and the vacuum chamber can be well described by the Hagen-Poiseuille flow equation, indicating that the viscosity of the neutral gas is the dominant factor for producing this pressure gradient. A potential profile analysis suggested that the plasma was mainly heated within cylindrical channels whose inner diameter was 3 mm. This feature and the results of the pressure ratio analysis indicated that the temperature, and, thus, viscosity, of the neutral gas increased with the increasing number of intermediate electrodes. The discharge characteristics and shape of the hollow cathode are suitable for plasma window applications.

A new multi-tracer pellet injection for a simultaneous study of low- and mid/high-Z impurities in high-temperature plasmas.

A new multi-tracer technique in the Tracer-Encapsulated Solid Pellet (TESPEL) method has been developed in order to acquire simultaneously the information about the behaviors of various impurities, i.e., to study concurrently the behaviors of low- and mid/high-Z impurities in magnetically confined high-temperature plasmas. In this new technique, an inorganic compound (for example, lithium titanate, Li2TiO3) is proposed to be used as a tracer embedded in the core of the TESPEL, instead of pure elements. The results of the proof-of-principle experiment clearly demonstrate the applicability of the new multi-tracer technique in the TESPEL method for the simultaneous study of behaviors of low- and mid/high-Z impurities in high-temperature plasmas.

Preservation of erniettomorph fossils in clay-rich siliciclastic deposits from the Ediacaran Wood Canyon Formation, Nevada.

Three-dimensionally preserved Ediacaran fossils occur globally within sandstone beds. Sandy siliciclastic deposits of the Ediacaran Wood Canyon Formation (WCF) in the Montgomery Mountains, Nevada, contain two fossil morphologies with similar shapes and sizes: one exhibits mm-scale ridges and a distinct lower boundary and the other is devoid of these diagnostic features. We interpret these as taphomorphs of erniettomorphs, soft-bodied organisms with uncertain taxonomic affinities. We explore the cast-and-mould preservation of both taphomorphs by petrography, Raman spectroscopy, X-ray fluorescence microprobe and X-ray diffraction. All fossils and the surrounding sedimentary matrix contain quartz grains, iron-rich chlorite and muscovite. The ridged fossils contain about 70% larger quartz grains compared to the ridgeless taphomorph, indicating a lower abundance of clay minerals in the ridged fossil. Chlorite and muscovite likely originated from smectite and kaolinite precursors that underwent lower greenschist facies metamorphism. Kaolinite and smectite are inferred to have been abundant in sediments around the ridged fossil, which enabled the preservation of a continuous, distinct, clay- and kerogen-rich bottom boundary. The prevalence of quartz in the ridged fossils of the WCF and in erniettomorphs from other localities also suggests a role for this mineral in three-dimensional preservation of erniettomorphs in sandstone and siltstone deposits.

Tracer-Encapsulated Solid Pellet (TESPEL) injection system for Wendelstein 7-X.

Impurity confinement in fusion plasmas is mainly determined by transport mechanisms in the core region. For the Wendelstein 7-X stellarator, its island divertor is expected to screen effectively external impurity sources in the scrape-off layer at higher densities. However, the unique feature of Tracer-Encapsulated Solid Pellet (TESPEL) injection, releasing impurities at a well-localized radial position directly in the core plasma, enables investigating such transport mechanisms. This paper reports on the detailed design of a completely new TESPEL injection system, which has been designed by the National Institute for Fusion Science, Toki, Japan, and is currently being installed at Max-Planck-Institut für Plasmaphysik, Greifswald, Germany, for the Wendelstein 7-X. This injector consists of a storage and injection unit, attached to a system of guiding tubes which run through 3 successive differential pumping stages. A light-gate system and an optical observation system are used to determine the location of the deposited tracers. Laboratory tests carried out by shooting TESPELs onto a sample foil showed good performance after careful realignment of the guiding tubes.

Development of a tracer-containing compact-toroid injection system.

The accumulation and behavior of impurities is one of the most important subjects in the development of magnetically confined fusion reactors because impurities can potentially cause cooling and worsen the confinement of the hot core plasma. Tracer-encapsulated solid pellets (TESPELs) have demonstrated some results for impurity injection for fusion-reactor plasma studies [N. Tamura et al., J. Phys. Conf. Ser. 823, 012003 (2017)]. However, the TESPEL technique has several shortcomings, for example, the penetration depth and the amounts of tracer impurities. In the present study, we have developed a tracer-containing, compact-toroid (TCCT) injection system that utilizes a magnetized coaxial plasma gun (MCPG). The discharge current through the MCPG sputters and ionizes the electrode material, and the Lorenz self-force accelerates it as a plasmoid. The MCPG easily accelerates a magnetized plasmoid to speeds greater than the ion thermal velocity of several tens of kilometers per second. The accelerated and ejected plasmoid that contains the tracer ions is itself a warm, ionized plasma. Therefore, a TCCT can potentially be injected into the core region of a target plasma with less adverse effect.

A retrospective cohort study investigating risk factors for the failure of Thoroughbred racehorses to return to racing after superficial digital flexor tendon injury.

A retrospective cohort study was conducted to investigate risk factors for the failure of Thoroughbred racehorses to return to racing after an injury of the superficial digital flexor tendon (SDFT). Successful return was defined as the completion of five or more races after SDFT injury. The official Japan Racing Association (JRA) medical records of racehorses with a core-type SDFT injury were reviewed for clinical variables related to the characteristics of the horse and the severity of SDFT injuries at the time of diagnosis. Data on racing outcomes were obtained from the official JRA racing database. Risk factors were screened using univariable logistic regression and subsequent multivariable model building. Forty-nine of 346 (14.2%) horses successfully returned to racing after SDFT injuries. Multivariable model building revealed that an increase in the total number of injured zones (defined as the total number of zones in which the injured hypoechoic area was observed at the time of ultrasonographic diagnosis of SDFT injury) was associated with an increased risk of failure to return to racing after SDFT injury. Horse characteristics, such as age, body mass and sex, were not associated with a successful return to racing. In the rehabilitation of cases with larger (longer) lesions, more effective and careful medical management may be needed for an improvement in the athletic outcomes.

Role of Multichance Fission in the Description of Fission-Fragment Mass Distributions at High Energies.

Fission-fragment mass distributions were measured for ^{237-240}U, ^{239-242}Np, and ^{241-244}Pu populated in the excitation-energy range from 10 to 60 MeV by multinucleon transfer channels in the reaction ^{18}O+^{238}U at the Japan Atomic Energy Agency tandem facility. Among them, the data for ^{240}U and ^{240,241,242}Np were observed for the first time. It was found that the mass distributions for all the studied nuclides maintain a double-humped shape up to the highest measured energy in contrast to expectations of predominantly symmetric fission due to the washing out of nuclear shell effects. From a comparison with the dynamical calculation based on the fluctuation-dissipation model, this behavior of the mass distributions was unambiguously attributed to the effect of multichance fission.

The use of sonoelastography to assess the recovery of stiffness after equine superficial digital flexor tendon injuries: A preliminary prospective longitudinal study of the healing process.

BACKGROUND: The objective assessment of the mechanical properties of the superficial digital flexor tendon (SDFT) could provide useful information for the rehabilitation of horses with SDFT injuries. Assessment of strain ratio (the strain of a standard reference divided by that of lesions) is a quantitative method in sonoelastography for evaluating tissue stiffness in vivo. As yet, no longitudinal studies have used strain ratio to evaluate the progression of stiffness in SDFT injuries. OBJECTIVES: To test the hypothesis that strain ratio can evaluate the recovery of stiffness during the healing of SDFT injuries. STUDY DESIGN: Prospective and longitudinal study with observer-blinded evaluation. METHODS: Ultrasonography, including sonoelastography, was performed in seven Thoroughbred horses with naturally occurring SDFT injuries at five time points: within 20 days of the injury, and at 2, 3, 6 and 9 months after the injury. Blinded sonoelastographic images were independently evaluated by two veterinarians to assess interobserver agreement. The recovery of stiffness and echogenicity in lesions were evaluated using the strain ratio and grey-scale ratio (echogenicity of lesions divided by that of the surrounding area), respectively. RESULTS: Interobserver agreement was assessed as 'almost perfect'. Strain ratios were significantly higher at 9 months after injury than at the other time points (all P<0.05). Strain ratios at 6 months after injury were significantly higher than those at earlier time points (P<0.05). Grey-scale ratios within 20 days of injury were significantly lower than those at the other time points (all P<0.05). MAIN LIMITATIONS: Validations of SDFT status were evaluated only by recovery of the echogenicity in lesions and not by histopathological examination. CONCLUSIONS: Although further studies are needed to validate the relationships between injured SDFT status and sonoelastographic findings, this preliminary study shows that strain ratio may provide a means to monitor the recovery of stiffness in lesions during rehabilitation, even when the grey-scale ratio remains unchanged from a few months after SDFT injury. The Summary is available in Chinese - see Supporting Information.

Application of sonoelastography for evaluating the stiffness of equine superficial digital flexor tendon during healing.

Sonoelastography can assess the inner stiffness of tissues. Sonoelastographic evaluation of injured equine superficial digital flexor tendons (SDFTs) is considered to be useful for assessing the stiffness of a lesion even during late-stage rehabilitation. The purpose of this study was to investigate and compare the sonoelastographic appearance of injured SDFTs over time from the onset of the injury. Eighteen horses were classified into three groups according to the length of time from injury onset: group A, within two weeks after injury; group B, approximately five months after injury; and group C, approximately nine months after injury. Longitudinal and transverse images of all injured SDFTs were obtained using grey-scale ultrasonography and sonoelastography. Grey-scale and sonoelastographic images were evaluated by two observers using echogenicity-grading and colour-grading systems, respectively. The authors evaluated the interobserver agreement and compared the grades among the three groups. The results indicated almost perfect interobserver agreement. Significant differences were found in the sonoelastography among the three groups, whereas no significant difference was found in the grey-scale ultrasonography between groups B and C. Sonoelastography is a feasible and useful modality to evaluate the equine injured SDFTs in vivo and to distinguish between them among the different phases even during the chronic phase.

Associated factors of behavioural problems in children at preschool age: the Hokkaido study on environment and children's health.

BACKGROUND: Finding associated factors with childhood behavioural problems as early as preschool age is important. Studies have revealed several factors including socioeconomic factors, which may vary among different cultural background and population. However, investigation in general Japanese population of preschool age has not been well demonstrated. Thus, the objective of this study was to examine associated factors of childhood behavioural problems using Strengths and Difficulties Questionnaire (SDQ) in a prospective birth cohort study. METHODS: Total 3813 SDQ were distributed between October 2014 and December 2015 to the subpopulation of prospective birth cohort study, the Hokkaido Study on Environment and Children's Health. The subpopulation consisted of participants who had reached age 5 and were born between April 2008 and December 2010. Baseline questionnaire filled at recruitment and birth record were used to obtain participant information. Children with total difficulties score ≧ 13 were defined as likelihood of behavioural problems. A total of 2553 children with valid answers were included into the analysis. The response rate was 67.1%. RESULTS: Number of children with likelihood of behavioural problems was 521 (20.4%). Boys showed more problematic scores than girls. Multivariate analysis found that maternal pre-pregnancy BMI ≧ 30 kg/m2 , primipara, maternal education lower than high school, family income during pregnancy < 3 million yen/year and boy gender were the factors associated with increased odds ratio of likelihood of child behavioural problems. CONCLUSIONS: This study found that prenatal socioeconomic factors were associated with likelihood of child behavioural problems at preschool age in Japan.

Tracer-Encapsulated Solid Pellet (TESPEL) injection system for the TJ-II stellarator.

A tracer-encapsulated solid pellet (TESPEL) injection system for the TJ-II stellarator was recently developed. In order to reduce the time and cost for the development, we combined a TESPEL injector provided by National Institute for Fusion Science with an existing TJ-II cryogenic pellet injection system. Consequently, the TESPEL injection into the TJ-II plasma was successfully achieved, which was confirmed by several pellet diagnostics including a normal-incidence spectrometer for monitoring a tracer impurity behavior.

Development of a new tracer-encapsulated solid pellet injection system for more precise control of tracer-impurity-deposit location in LHD.

A new tracer-encapsulated solid pellet (TESPEL) injection system has been developed additionally for the LHD heliotron. This system has three-dimensionally bended guide tubes, which allows us to inject the TESPEL obliquely on a poloidal cross-section of the LHD plasma. Consequently, this system enables us to control a tracer-impurity-deposited location more precisely. Moreover, this system can make it possible for the tracer impurity to be deposited even only inside the ergodic region (outside a last closed flux surface of the LHD plasma). A stereoscopic fast camera system has been also developed for capturing a three-dimensional TESPEL trajectory.

Rotating lattice single crystal architecture on the surface of glass.

Defying the requirements of translational periodicity in 3D, rotation of the lattice orientation within an otherwise single crystal provides a new form of solid. Such rotating lattice single (RLS) crystals are found, but only as spherulitic grains too small for systematic characterization or practical application. Here we report a novel approach to fabricate RLS crystal lines and 2D layers of unlimited dimensions via a recently discovered solid-to-solid conversion process using a laser to heat a glass to its crystallization temperature but keeping it below the melting temperature. The proof-of-concept including key characteristics of RLS crystals is demonstrated using the example of Sb2S3 crystals within the Sb-S-I model glass system for which the rotation rate depends on the direction of laser scanning relative to the orientation of initially formed seed. Lattice rotation in this new mode of crystal growth occurs upon crystallization through a well-organized dislocation/disclination structure introduced at the glass/crystal interface. Implications of RLS growth on biomineralization and spherulitic crystal growth are noted.

Development of a cascade arc discharge source for an atmosphere-vacuum interface device.

To realize a novel vacuum-atmosphere interface that does not require a large differential pumping system, a robust cascade arc discharge source called a plasma window is constructed and tested for long-term operation. By modifying a test plasma with a direct current discharge, a vacuum interface with a high gas pressure ratio of 1/407 between the discharge and expansion sections is demonstrated for currents as high as 20 A. No significant damage to the electrodes is observed during the operation. Analysis of the visible emission spectra reveals that a stationary, stable argon plasma having a temperature of 1 eV and a density of 1.5 × 10(16) cm(-3) is generated in the plasma channel.

Meticillin-resistant Staphylococcus aureus colonisation and infection in Thoroughbred racehorses and veterinarians in Japan.

Meticillin-resistant Staphylococcus aureus (MRSA) infections have been confirmed in hospitalised Thoroughbred racehorses at the hospitals of two training centres in Japan since 2009. To investigate the source of infection, the authors examined the rate of nasal MRSA colonisation in 600 healthy Thoroughbred racehorses, 53 veterinarians and 16 office staff at the racehorse hospitals of the two training centres. MRSA was not isolated from healthy Thoroughbred racehorses or hospital office staff. However, MRSA was isolated from 16 veterinarians (30.1 per cent), and the colonisation rate was significantly higher in veterinarians than in the office staff of the same hospitals. Also, 10 of the 16 MRSA strains (62.5 per cent) isolated from veterinarians were classified as type II by staphylococcal cassette chromosome mec (SCCmec) typing and ST5 by multilocus sequence typing. Pulsed-field gel electrophoresis analysis demonstrated that these 10 MRSA strains of SCCmec type II and ST5 were genetically identical or very similar to 9 MRSA strains isolated from infected horses hospitalised at these hospitals between 2009 and 2013. These results indicate that SCCmec type II and ST5 MRSA strains were probably transmitted between veterinarians and infected horses.

Imaging polychromator for density measurements of polystyrene pellet cloud on the Large Helical Device.

Experimental data on spatial distributions of a pellet cloud electron density are necessary for the development of many applications of pellet injection, namely, plasma fuelling, discharge control, and plasma diagnostics. An improved approach of electron density measurements inside the cloud of a polystyrene pellet ablating in hot plasma of the large helical device is described. Density values of (1-30) × 10(16) cm(-3) depending on the background plasma parameters and distance from the solid pellet were measured.

Development of pro-apoptotic peptides as potential therapy for peritoneal endometriosis.

Endometriosis is a common gynaecological disease associated with pelvic pain and infertility. Current treatments include oral contraceptives combined with nonsteroidal anti-inflammatory drugs or surgery to remove lesions, all of which provide a temporary but not complete cure. Here we identify an endometriosis-targeting peptide that is internalized by cells, designated z13, using phage display. As most endometriosis occurs on organ surfaces facing the peritoneum, we subtracted a phage display library with female mouse peritoneum tissue and selected phage clones by binding to human endometrial epithelial cells. Proteomics analysis revealed the z13 receptor as the cyclic nucleotide-gated channel ß3, a sorting pathway protein. We then linked z13 with an apoptosis-inducing peptide and with an endosome-escaping peptide. When these peptides were co-administered into the peritoneum of baboons with endometriosis, cells in lesions selectively underwent apoptosis with no effect on neighbouring organs. Thus, this study presents a strategy that could be useful to treat peritoneal endometriosis in humans.

Transient ligation of umbilical vessels elevates placental tissue oxygen index (TOI) values measured by near-infrared spectroscopy (NIRS) in clawn miniature pig animal model.

We recently found a significant elevation in placental tissue oxygen index (TOI) values in cases of fetal growth restriction using near-infrared spectroscopy (NIRS), indicating high oxygenation in the placental tissue. We hypothesized that insufficient fetoumbilical blood flow is causatively associated with high oxygenation levels in placental tissue. We transiently (for 15 sec) ligated the whole umbilicus, umbilical arteries, or veins of pregnant Clawn miniature pigs (102-113 days of gestation) and assessed the changes in TOI values of the placenta and fetus. The ligation significantly increased placental TOI values (p<0.01, respectively), but concomitantly decreased fetal TOI values (p<0.01, respectively), suggesting a decline in oxygen inflow from the maternal to fetal circulation in the placental tissue to be causative of the elevated placental TOI values. These observations suggest the promising clinical use of placental TOI values measured noninvasively by the transabdominal application of NIRS to assess the fetoplacental circulation.

Immunohistochemical detection of meconium in the fetal membrane, placenta and umbilical cord.

OBJECTIVE: To develop the immunohistochemistry specific for meconium in the placenta, fetal membrane and umbilical cord. STUDY DESIGN: We previously reported the specific presence of zinc coproporphyrin I (ZnCP-I) in human meconium and demonstrated the possible diagnostic use of an elevation in maternal plasma ZnCP-I levels in cases of amniotic fluid embolism. In this study, we developed a new specific monoclonal antibody for ZnCP-I and applied it to the immunostaining of meconium in the placenta, fetal membrane, and umbilical cord. RESULTS: Immunoreactivity of ZnCP-I clearly and specifically identified meconium in the placenta, fetal membrane, and umbilical cord. It was especially useful in cases of severe chorioamnionitis to detect meconium in the macrophages surrounded by numerous neutrophils. In more than half of the cases, meconium was detected in clear amniotic fluid at delivery, suggesting previous exposure. CONCLUSIONS: Immunohistochemical detection of ZnCP-I is a highly sensitive histological diagnosis of meconium.

Observation of long-distance radial correlation in toroidal plasma turbulence.

This Letter presents the discovery of macroscale electron temperature fluctuations with a long radial correlation length comparable to the plasma minor radius in a toroidal plasma. Their spatiotemporal structure is characterized by a low frequency of ∼1-3 kHz, ballistic radial propagation, a poloidal or toroidal mode number of m/n=1/1 (or 2/1), and an amplitude of ∼2% at maximum. Nonlinear coupling between the long-range fluctuations and the microscopic fluctuations is identified. A change of the amplitude of the long-range fluctuation is transmitted across the plasma radius at the velocity which is of the order of the drift velocity.