Air kerma reference field with high energy photons using a 15 MeV electron beam from a clinical linear accelerator

In the medical and nuclear fields, there are environments where exposure to photons with energies above several MeV can result in problems. The National Metrology Institute of Japan has developed a high-energy photon field using a 15 MeV electron beam of a clinical linear accelerator with a copper target and an aluminium filter unit to facilitate dosimeter calibration in terms of air kerma. To determine the air kerma rate, the energy fluence distribution at a reference point was calculated, and both calculations and experiments evaluated the effective energy and spatial dose distribution. Moreover, to validate the air kerma measurement, two commercial cavity chambers were calibrated in a developed photon field. The results obtained exhibited a 4% difference compared with those in a Co-60γ-ray reference field.

DEVELOPMENT OF ABSOLUTE MEASUREMENT SYSTEM FOR 𝑾AIR IN 60CO GAMMA RAYS

In the ICRU Report 90, the uncertainty of the recommendation for ${{W}}_{{air}}$ was changed from 0.15 to 0.35%. The purpose of this study is to develop an absolute measurement system for ${{W}}_{{air}}$ in electrons with lower uncertainty using 60Co gamma rays. ${{W}}_{{air}}$ was determined by the ratio of the energy deposition to the number of ion pairs created in a given volume of air using a graphite calorimeter and a graphite-wall ionisation chamber. The obtained value for ${{W}}_{{air}}$ was 33.91 eV with a relative standard uncertainty of 0.08 eV (k = 1), and was in good agreement with the recommended value of the ICRU Report 90 (33.97 eV). Additionally, the uncertainty for ${{W}}_{{air}}$ obtained in this investigation is 0.23% and is comparable with that reported by Burns et al., which is the lowest uncertainty in recent studies determining ${{W}}_{{air}}$ In the future, the proposed system can be used to measure ${{W}}_{{air}}$ in high-energy electron beams.

Fate of charge order in overdoped La-based cuprates

In high-temperature cuprate superconductors, stripe order refers broadly to a coupled spin and charge modulation with a commensuration of eight and four lattice units, respectively. How this stripe order evolves across optimal doping remains a controversial question. Here we present a systematic resonant inelastic x-ray scattering study of weak charge correlations in La2-xSrxCuO4 and La1.8-xEu0.2SrxCuO4. Ultra high energy resolution experiments demonstrate the importance of the separation of inelastic and elastic scattering processes. Long-range temperature-dependent stripe order is only found below optimal doping. At higher doping, short-range temperature-independent correlations are present up to the highest doping measured. This transformation is distinct from and preempts the pseudogap critical doping. We argue that the doping and temperature-independent short-range correlations originate from unresolved electron-phonon coupling that broadly peaks at the stripe ordering vector. In La2-xSrxCuO4, long-range static stripe order vanishes around optimal doping and we discuss both quantum critical and crossover scenarios.

[Technical Report: Quality Assurance for 125I Seed Sources in Permanent Prostate Brachytherapy]

This technical report provides useful information on the current status and issues of quality control in ¹²⁵I seed source strength measurement for Permanent Prostate Brachytherapy in Japan.With the spread of ¹²⁵I seed brachytherapy, the traceability of source strength measurements with the single-seed assay was established in Japan. This allows medical facilities to measure reference air kerma rate of ¹²⁵I seeds with their own well-type of ionization chamber. However, it is difficult to maintain the traceability chain because the ¹²⁵I reference air kerma rate standards have been hardly utilized by medical facilities so far. Meanwhile, some serious incidents of contamination of the different source strengths and dead seeds were reported in Japan.To address the specific issues in Japan, JASTRO Brachytherapy Subcommittee established a working group (WG) in 2021. The goal of this WG is to investigate the management methods of source strength measurement used in medical facilities, and to discuss the ideal and practicable methods of source management such as verifying the number of seeds and source strength. Initially, a questionnaire survey was conducted to facilities offering ¹²⁵I seed brachytherapy in Japan. Sixty-seven out of 95 facilities responded (response rate 70.5%). This survey revealed that 41% of facilities did not perform either confirmation of the number of seeds or measurement of source strength. There are several reasons why the source strength was not measured in those facilities. For example, ¹²⁵I seeds are provided under the sterilized conditions; quality assurance by source suppliers is reliable; and there is not sufficient staff.The single-seed assay is regarded as an internationally standardized and the most reliable measurement method. Therefore, it is an essential measurement technique to ensure traceability of source strength measurements. However, our survey found that most Japanese facilities do not perform single-seed assays. Meanwhile, some facilities have performed batch assay as an alternative method, in which all of the multiple sources in a batch are measured while loaded into sterilized cartridges. Although the measurement by the batch assay is less accurate than the one by the single-seeded assay, the batch assay does not require re-sterilization of the source and can be performed quickly. It might be useful to detect unexpected errors such as differences in the number of sources and abnormalities in source strength.In this report, we will introduce several methods of source strength measurement that have been implemented in medical facilities. The quality assurance of ¹²⁵I seed sources in prostate interstitial brachytherapy should be provided not only by the source suppliers but also by the medical facilities that use sources to treat patients. We hope that medical facilities will refer to this technical report and use it as an aid to quality assurance in their own facilities.

Evidence for a Square-Square Vortex Lattice Transition in a High-T_{c} Cuprate Superconductor

Using sound velocity and attenuation measurements in high magnetic fields, we identify a new transition in the vortex lattice state of La_{2-x}Sr_{x}CuO_{4}. The transition, observed in magnetic fields exceeding 35 T and temperatures far below zero field T_{c}, is detected in the compression modulus of the vortex lattice, at a doping level of x=p=0.17. Our theoretical analysis based on Eilenberger's theory of the vortex lattice shows that the transition corresponds to the long-sought 45° rotation of the square vortex lattice, predicted to occur in d-wave superconductors near a van Hove singularity.

Unveiling Unequivocal Charge Stripe Order in a Prototypical Cuprate Superconductor

In the cuprates, high-temperature superconductivity, spin-density-wave order, and charge-density-wave (CDW) order are intertwined, and symmetry determination is challenging due to domain formation. We investigated the CDW in the prototypical cuprate La_{1.88}Sr_{0.12}CuO_{4} via x-ray diffraction employing uniaxial pressure as a domain-selective stimulus to establish the unidirectional nature of the CDW unambiguously. A fivefold enhancement of the CDW amplitude is found when homogeneous superconductivity is partially suppressed by magnetic field. This field-induced state provides an ideal search environment for a putative pair-density-wave state.

The NMIJ air kerma primary standard for high energy x-ray beams in 300-450 kV

Accurate radiation dosimetry is required for radiation protection in various environments. Therefore, dosemeters and dose-rate meters must be calibrated in standard radiation fields. The National Metrology Institute of Japan (NMIJ) expands the energy range of x-ray reference field measurement up to 450 kV using a cylindrical graphite-walled cavity ionization chamber. Departure from the condition of the Spencer-Attix cavity theory was evaluated by comparing the measurement results obtained using the cavity ionization and the free-air ionization chambers, which are used as the primary standard up to a tube voltage of 250 kV. The calibration coefficients found using the spherical ionization chamber were in good agreement with those obtained by the free-air ionization chamber within relative standard uncertainties (k = 1) for N-200 and N-250 x-ray fields. Consistent calibration coefficients were obtained in the energy range 300-450 kV.

Evaluation of apocynin in vitro on high glucose-induced oxidative stress on tenocytes

Aims

The purpose of this study was to evaluate the in vitro effects of apocynin, an inhibitor of nicotinamide adenine dinucleotide phosphate oxidase (NOX) and a downregulator of intracellular reactive oxygen species (ROS), on high glucose-induced oxidative stress on tenocytes.

Methods

Tenocytes from normal Sprague-Dawley rats were cultured in both control and high-glucose conditions. Apocynin was added at cell seeding, dividing the tenocytes into four groups: the control group; regular glucose with apocynin (RG apo+); high glucose with apocynin (HG apo+); and high glucose without apocynin (HG apo–). Reactive oxygen species production, cell proliferation, apoptosis and messenger RNA (mRNA) expression of NOX1 and 4, and interleukin-6 (IL-6) were determined in vitro.

Results

Expression of NOX1, NOX4, and IL-6 mRNA in the HG groups was significantly higher compared with that in the RG groups, and NOX1, NOX4, and IL-6 mRNA expression in the HG apo+ group was significantly lower compared with that in the HG apo– group. Cell proliferation in the RG apo+ group was significantly higher than in the control group and was also significantly higher in the HG apo+ group than in the HG apo– group. Both the ROS accumulation and the amounts of apoptotic cells in the HG groups were greater than those in the RG groups and were significantly less in the HG apo+ group than in the HG apo– group.

Conclusion

Apocynin reduced ROS production and cell death via NOX inhibition in high-glucose conditions. Apocynin is therefore a potential prodrug in the treatment of diabetic tendinopathy.

Cite this article:Bone Joint Res 2020;9(1):23–28.

High-Temperature Charge-Stripe Correlations in La_{1.675}Eu_{0.2}Sr_{0.125}CuO_{4}

We use resonant inelastic x-ray scattering to investigate charge-stripe correlations in La_{1.675}Eu_{0.2}Sr_{0.125}CuO_{4}. By differentiating elastic from inelastic scattering, it is demonstrated that charge-stripe correlations precede both the structural low-temperature tetragonal phase and the transport-defined pseudogap onset. The scattering peak amplitude from charge stripes decays approximately as T^{-2} towards our detection limit. The in-plane integrated intensity, however, remains roughly temperature independent. Therefore, although the incommensurability shows a remarkably large increase at high temperature, our results are interpreted via a single scattering constituent. In fact, direct comparison to other stripe-ordered compounds (La_{1.875}Ba_{0.125}CuO_{4}, La_{1.475}Nd_{0.4}Sr_{0.125}CuO_{4}, and La_{1.875}Sr_{0.125}CuO_{4}) suggests a roughly constant integrated scattering intensity across all these compounds. Our results therefore provide a unifying picture for the charge-stripe ordering in La-based cuprates. As charge correlations in La_{1.675}Eu_{0.2}Sr_{0.125}CuO_{4} extend beyond the low-temperature tetragonal and pseudogap phase, their emergence heralds a spontaneous symmetry breaking in this compound.

Coexistence of the Kondo effect and spin glass physics in Fe-doped NbS2

We report the coexistence of the Kondo effect and spin glass behavior in Fe-doped NbS₂ single crystals. The Fe _x NbS₂ shows the resistance minimum and negative magnetoresistance due to the Kondo effect, and exhibits no superconducting behavior at low temperatures. The resistance curve follows a numerical renormalization-group theory using the Kondo temperature [Formula: see text] K for x  =  0.01 as evidence of Kondo effect. Scanning tunneling microscope/spectroscopy (STM/STS) revealed the presence of Fe atoms near sulfur atoms and asymmetric spectra. The magnetic susceptibility exhibits a feature of spin glass. The static critical exponents determined by the universal scaling of the nonlinear part of the susceptibility suggest a three-dimensional Heisenberg spin glass. The doped-Fe atoms in the intra- and inter-layers revealed by the x-ray result can realize the coexistence of the Kondo effect and spin glass.

Direct observation of orbital hybridisation in a cuprate superconductor

The minimal ingredients to explain the essential physics of layered copper-oxide (cuprates) materials remains heavily debated. Effective low-energy single-band models of the copper–oxygen orbitals are widely used because there exists no strong experimental evidence supporting multi-band structures. Here, we report angle-resolved photoelectron spectroscopy experiments on La-based cuprates that provide direct observation of a two-band structure. This electronic structure, qualitatively consistent with density functional theory, is parametrised by a two-orbital (\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$d_{x^2 - y^2}$$\end{document}dx2-y2 and \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$d_{z^2}$$\end{document}dz2) tight-binding model. We quantify the orbital hybridisation which provides an explanation for the Fermi surface topology and the proximity of the van-Hove singularity to the Fermi level. Our analysis leads to a unification of electronic hopping parameters for single-layer cuprates and we conclude that hybridisation, restraining d-wave pairing, is an important optimisation element for superconductivity.

The essential physics of cuprate superconductors is often described by single-band models. Here, Matt et al. report direct observation of a two-band electronic structure in La-based cuprates.

Measuring and assessing individual external doses during the rehabilitation phase in Iitate village after the Fukushima Daiichi nuclear power plant accident

After the Fukushima Daiichi nuclear power plant accident in 2011, Iitate village was placed under an evacuation order because the level of radioactive materials drifting from the nuclear plant to the village was above a government-set level for allowing residents to live in the area. The evacuation advisory for most of the village was lifted on 31 March 2017. For displaced residents deciding whether or not to return to their homes, it is important to correctly understand and estimate the realistic individual external doses they will receive after returning to the village. In this study, with the support of residents of the village, we used a personal dosimeter (D-Shuttle) coupled with a global positioning system device to measure and thus understand realistic individual external doses while the residents were in Iitate village and to project the individual external doses for different administrative districts as of 1 April 2017. The measured individual external doses measured by D-Shuttle for 38 study participants showed that the doses measured during time spent inside the village were higher and more widely distributed than the doses measured during time spent outside the village. The exposure ratio (ER) was defined as the ratio of additional individual external dose measured by D-Shuttle to the additional ambient dose based on an airborne monitoring survey. The medians of the average ERs were 0.13 (min-max 0.06-0.27) for time spent at home and 0.18 (min-max 0.08-0.36) for time spent outdoors. Projected additional annual individual external doses as of 1 April 2017 for different administrative districts in the village were calculated using ERs obtained in this study. Assuming that individuals spent 8 h per day on outdoor activities and 16 h on indoor activities, additional annual individual external doses were estimated to be below 3 mSv using the mean of the average ERs for most districts in the village, and these values were well below the individual external doses estimated using the approach taken by the central government. The results of this study provide valuable information both for understanding realistic radiological situations in the village and for those who want to know their future individual external dose in order to make a decision on whether or not to live in the village.

Current situations and discussions in Japan in relation to the new occupational equivalent dose limit for the lens of the eye

Since the International Commission on Radiological Protection recommended reducing the occupational equivalent dose limit for the lens of the eye in 2011, there have been extensive discussions in various countries. This paper reviews the current situation in radiation protection of the ocular lens and the discussions on the potential impact of the new lens dose limit in Japan. Topics include historical changes to the lens dose limit, the current situation with occupational lens exposures (e.g., in medical workers, nuclear workers, and Fukushima nuclear power plant workers) and measurements, and the current status of biological studies and epidemiological studies on radiation cataracts. Our focus is on the situation in Japan, but we believe such information sharing will be useful in many other countries.

SIMPLIFIED PRACTICAL TEST METHOD FOR PORTABLE DOSE METERS USING SEVERAL SEALED RADIOACTIVE SOURCES

Sealed radioactive sources which have small activity were employed for the determination of response and tests for non-linearity and energy dependence of detector responses. Close source-to-detector geometry (at 0.3 m or less) was employed to practical tests for portable dose meters to accumulate statistically sufficient ionizing currents. Difference between response in the present experimentally studied field and in the reference field complied with ISO 4037 due to non-uniformity of radiation fluence at close geometry was corrected by use of Monte Carlo simulation. As a consequence, corrected results were consistent with the results obtained in the ISO 4037 reference field within their uncertainties.

Relationship between Individual External Doses, Ambient Dose Rates and Individuals' Activity-Patterns in Affected Areas in Fukushima following the Fukushima Daiichi Nuclear Power Plant Accident

The accident at Fukushima Daiichi Nuclear Power Plant on March 11, 2011, released radioactive material into the atmosphere and contaminated the land in Fukushima and several neighboring prefectures. Five years after the nuclear disaster, the radiation levels have greatly decreased due to physical decay, weathering, and decontamination operations in Fukushima. The populations of 12 communities were forced to evacuate after the accident; as of March 2016, the evacuation order has been lifted in only a limited area, and permanent habitation is still prohibited in most of the areas. In order for the government to lift the evacuation order and for individuals to return to their original residential areas, it is important to assess current and future realistic individual external doses. Here, we used personal dosimeters along with the Global Positioning System and Geographic Information System to understand realistic individual external doses and to relate individual external doses, ambient doses, and activity-patterns of individuals in the affected areas in Fukushima. The results showed that the additional individual external doses were well correlated to the additional ambient doses based on the airborne monitoring survey. The results of linear regression analysis suggested that the additional individual external doses were on average about one-fifth that of the additional ambient doses. The reduction factors, which are defined as the ratios of the additional individual external doses to the additional ambient doses, were calculated to be on average 0.14 and 0.32 for time spent at home and outdoors, respectively. Analysis of the contribution of various activity patterns to the total individual external dose demonstrated good agreement with the average fraction of time spent daily in each activity, but the contribution due to being outdoors varied widely. These results are a valuable contribution to understanding realistic individual external doses and the corresponding airborne monitoring-based ambient doses and time-activity patterns of individuals. Moreover, the results provide important information for predicting future cumulative doses after the return of residents to evacuation order areas in Fukushima.

Evidence for carrier localization in the pseudogap state of cuprate superconductors from coherent quench experiments

A 'pseudogap' was introduced by Mott to describe a state of matter that has a minimum in the density of states at the Fermi level, deep enough for states to become localized. It can arise either from Coulomb repulsion between electrons, and/or incipient charge or spin order. Here we employ ultrafast spectroscopy to study dynamical properties of the normal to pseudogap state transition in the prototype high-temperature superconductor Bi2Sr2CaCu2O8+δ. We perform a systematic temperature and doping dependence study of the pseudogap photodestruction and recovery in coherent quench experiments, revealing marked absence of critical behaviour of the elementary excitations, which implies an absence of collective electronic ordering beyond a few coherence lengths on short timescales. The data imply ultrafast carrier localization into a textured polaronic state arising from a competing Coulomb interaction and lattice strain, enhanced by a Fermi surface instability.

Comparison of the NMIJ and the ARPANSA standards for absorbed dose to water in high-energy photon beams

The authors report the results of an indirect comparison of the standards of absorbed dose to water in high-energy photon beams from a clinical linac and (60)Co radiation beam performed between the National Metrology Institute of Japan (NMIJ) and the Australian Radiation Protection and Nuclear Safety Agency (ARPANSA). Three ionisation chambers were calibrated by the NMIJ in April and June 2013 and by the ARPANSA in May 2013. The average ratios of the calibration coefficients for the three ionisation chambers obtained by the NMIJ to those obtained by the ARPANSA were 0.9994, 1.0040 and 1.0045 for 6-, 10- and 15-MV (18 MV at the ARPANSA) high-energy photon beams, respectively. The relative standard uncertainty of the value was 7.2 × 10(-3). The ratio for (60)Co radiation was 0.9986(66), which is consistent with the results published in the key comparison of BIPM.RI(I)-K4.

A standard for absorbed dose rate to water in a 60Co field using a graphite calorimeter at the National Metrology Institute of Japan

A primary standard for the absorbed dose rate to water in a ⁶⁰Co radiation field has been newly established at the National Metrology Institute of Japan. This primary standard combines the calorimetric measurements using a graphite calorimeter with the ionometric measurements using a thick-walled graphite cavity ionisation chamber. The calorimeter is operated in the constant temperature mode using AC Wheatstone bridges. The absorbed dose rate to water was determined to be 12 mGy s⁻¹ at a point of 1 m from the radiation source and at a water depth of 5 g cm⁻². The uncertainty on the calibration coefficient in terms of the absorbed dose to water of an ionisation chamber using this standard was estimated to be 0.39 % (k=1).

A randomized, controlled trial of fingolimod (FTY720) in Japanese patients with multiple sclerosis

BACKGROUND

Fingolimod (FTY720) has previously shown clinical efficacy in phase II/III studies of predominantly Caucasian populations with multiple sclerosis (MS).

OBJECTIVES

To report six-month efficacy and safety outcomes in Japanese patients with relapsing MS treated with fingolimod.

METHODS

In this double-blind, parallel-group, phase II study, 171 Japanese patients with relapsing MS were randomized to receive once-daily fingolimod 0.5 mg or 1.25 mg, or matching placebo for six months. The primary and secondary endpoints were the percentages of patients free from gadolinium (Gd)-enhanced lesions at months 3 and 6, and relapses over six months, respectively; safety outcomes were also assessed.

RESULTS

147 patients completed the study. Higher proportions of patients were free from Gd-enhanced lesions at months 3 and 6 with fingolimod (0.5 mg: 70%, p = 0.004; 1.25 mg: 86%, p < 0.001) than with placebo (40%). Odds ratios for the proportions of relapse-free patients over six months favoured fingolimod versus placebo but were not significant. Adverse events related to fingolimod included transient bradycardia and atrioventricular block at treatment initiation, and elevated liver enzyme levels.

CONCLUSIONS

This study demonstrated the clinical efficacy of fingolimod for the first time in Japanese patients with MS, consistent with the established effects of fingolimod in Caucasian patients.

Effect of the diaphragm of free-air ionisation chamber for X-ray air-kerma measurements

Free-air ionisation chambers are widely used at standards laboratories as primary standards for absolute measurements of air kerma in X-ray fields. The area of the diaphragm aperture of a free-air ionisation chambers is an important factor for absolute measurements because it defines the size of the X-ray beam incident on the free-air chamber. In this study, correction factors for the contribution of X rays transmitted through the diaphragm of a free-air ionisation chamber and those scattered from the surface of the diaphragm aperture are obtained by Monte Carlo simulation for two different sized free-air ionisation chambers and for various diaphragm aperture sizes, X-ray energies and source-to-chamber distances.

Chiral charge-density waves

We discovered the chirality of charge-density waves (CDW) in 1T-TiSe₂ by using STM and time-domain optical polarimetry. We found that the CDW intensity becomes Ia₁∶Ia₂∶Ia₃ = 1∶0.7 ± 0.1∶0.5 ± 0.1, where Ia(i) (i=1,2,3) is the amplitude of the tunneling current contributed by the CDWs. There were two states, in which the three intensity peaks of the CDW decrease clockwise and anticlockwise. The chirality in CDW results in the threefold symmetry breaking. Macroscopically, twofold symmetry was indeed observed in optical measurement. We propose the new generalized CDW chirality H(CDW) ≡ q₁·(q₂×q₃), where q(i) are the CDW q vectors, which is independent of the symmetry of components. The nonzero H(CDW)-the triple-q vectors do not exist in an identical plane in the reciprocal space-should induce a real-space chirality in CDW system.

Ectopic ossification with haematopoietic bone marrow in the heart valves of a crossbred heavy horse

Ectopic bone formation in the left atrioventricular valves and cardiac fibroskeleton, with systemic circulatory disturbance, is reported in a 4-year-old crossbred heavy horse. Microscopically, there was fibrosis, chondral metaplasia and mature bone, with bone marrow within the left atrioventricular cusps and in the annuli of the aortic and right atrioventricular valves.

Development of improved free-air ionisation chamber as absolute dosimetry standard for low-energy X rays in INER

The National Radiation Standard Laboratory of the Institute of Nuclear Energy Research (INER) designed and constructed an improved Attix style free-air ionisation chamber (FAC) for low-energy X-ray measurements. Clinically, X rays in this energy range are used in mammography radiology. This chamber is also used to perform air-kerma measurements. The original Attix two-sectional design was redesigned by INER using the piston design. The correction factors were determined experimentally for volume estimation, ion recombination and air attenuation. The aperture transmission, wall transmission, electron loss and photon scatter correction factors were determined using Monte Carlo calculations. INER established the Bureau International des Poids et Mesures (BIPM) X-ray beam code and performed a comparison of secondary standard air-kerma calibration factors for 10-50 kV low- energy X rays to verify the experimental accuracy and measurement consistency of the improved chamber. The INER-NMIJ/National Institute of Advanced Industrial Science and Technology (AIST) experimental results comparison using a transfer chamber yielded a difference <1.0% at the 95% confidence level in calibration factors. The overall uncertainty for the X-ray measurement in terms of air kerma was <0.6% at the 95% confidence level. These results indicated that the improved FAC is capable of serving as a primary standard as well as a trace standard in low-energy X-ray calibration services in Taiwan and even forming a basis for the future mammography X-ray air-kerma primary standard.

Epithelioid cells in mediastinal lymph nodes of cattle without cancer

Epithelioid cells are found in lymph nodes in cases of metastatic carcinoma; however, epithelioid cells with benign features have also been discovered incidentally in lymph nodes. Epithelioid cells were observed in mediastinal lymph nodes of cattle without cancer during routine diagnostic necropsy. To explain this finding, the authors evaluated the prevalence and histopathologic, immunohistochemical, and ultrastructural features retrospectively using mediastinal lymph nodes from 110 cattle and found that 66 of the lymph nodes contained epithelioid cells. In all 66 nodes, most of the epithelioid cells were individual or aggregated in nodal sinuses; in 21 nodes, some epithelioid cells formed tubular structures. The individual and aggregated epithelioid cells were mostly considered to be mesothelial in origin by immunohistochemical and ultrastructural examination; presumably, they entered the lymph nodes via lymphatic vessels, because they were found in afferent lymphatic vessels and nodal sinuses. Although the presence of epithelioid cells in lymph nodes prompts suspicion of metastatic carcinoma, the epithelioid cells in these bovine lymph nodes did not disrupt nodal architecture, lacked atypia or mitotic figures, and did not invade nodal parenchyma.

A reliable method for the counting and control of single ions for single-dopant controlled devices

By 2016, transistor device size will be just 10 nm. However, a transistor that is doped at a typical concentration of 10(18) atoms cm(-3) has only one dopant atom in the active channel region. Therefore, it can be predicted that conventional doping methods such as ion implantation and thermal diffusion will not be available ten years from now. We have been developing a single-ion implantation (SII) method that enables us to implant dopant ions one-by-one into semiconductors until the desired number is reached. Here we report a simple but reliable method to control the number of single-dopant atoms by detecting the change in drain current induced by single-ion implantation. The drain current decreases in a stepwise fashion as a result of the clusters of displaced Si atoms created by every single-ion incidence. This result indicates that the single-ion detection method we have developed is capable of detecting single-ion incidence with 100% efficiency. Our method potentially could pave the way to future single-atom devices, including a solid-state quantum computer.

A new method for identifying rigid link models of lower limbs

A new method for identifying rigid link models of human lower limbs has been proposed in this paper. The method was motivated by necessity of simulating human body movements for rehabilitation or for design of assistive devices. The method is based on combination of random search and least squares estimation techniques. Simulation and experimental results are given to illustrate the effectiveness of the proposed method.

The effect of angiotensin receptor blockade ARB on the regression of left ventricular hypertrophy in hemodialysis patients: comparison between patients with D allele and non-D allele ACE gene polymorphism

OBJECTIVE

It is revealed that LVH is one of risk factors for the development of cardiac complications in long-term HD patients. Therefore, maneuvers to reduce hypertrophy of cardium are very important for improving life prognosis. Angiotensin II receptor blockade (ARB) could reduce LVH in general populations without renal failure. However, no conclusive data has been available regarding the clinical consequences of ARB administration on the regression of LVH in HD patients. Furthermore, it has not clearly determined if ACE gene polymorphism has a possible influential effect on it. This study is conducted to clarify these issues.

SUBJECTS AND METHOD

32 hypertensive patients on regular HD (male/female: 21/11, mean age: 60.5 years, mean duration of HD: 52.8 months) were studied. Patients were classified into two groups according to the different type of ACE gene polymorphism: cases with D allele (DD/ID; D group: n = 13) and those without (II; non-D group: n = 19). All patients were administered ARB (losartan 50 - 100 mg/day) and echocardiography (UCG) was performed at 6-month-interval regularly until the end of observation (24 months).

RESULTS

Before the commencement of ARB, no differences were found between the two groups, neither in mean blood pressure (MBP: D group/non-D group: 120 +/- 13 vs. 115 +/- 14 mmHg) nor in left ventricular mass index (LVMI: D/non-D: 172 +/- 41 vs. 165 +/- 41 g/m2). During the 24r-month follow-up, there were significant and similar reductions in MBP in both groups. In respect to LVMI, a significant reduction of LVMI was found in the D group after six months (p < 0.01 vs. basal) with a final reduction rate (FRR) -26 +/- 13%, whereas in the non-D group it was found at 24 months (p < 0.01 vs. basal) with FRR -11 +/- 16% (p < 0.01 vs. D group). There were significant differences between the two groups at all points (p < 0.05 at 6, 18 and 24 months, p < 0.005 at 12 months, respectively).

CONCLUSION

It is indicated that ARB could insert a regression effect on LVH predominantly in patients with D allele ACE polymorphism, due partly to factor (s) independent of its anti-hypertensive effect.

Loss of ions in cavity ionization chambers

Ion losses due to initial recombination, volume recombination, and back diffusion were each determined by measurements and calculations for different size cylindrical ionization chambers and spherical ionization chambers. By measuring signal currents from these ionization chambers irradiated with (60)Co gamma rays, two groups of ion losses were obtained. (Group 1) Ion loss due to initial recombination and diffusion, which changes proportionally to the inverse of the voltage applied to the ionization chambers; (and group 2) ion loss due to volume recombination, which changes proportionally to the inverse of the square of the applied voltage. The diffusion loss was obtained separately by computing electric field distributions in the ionization chambers. It was found that diffusion loss is larger than initial recombination loss for the cylindrical ionization chambers and vise versa for the spherical ionization chambers.

Angular dependence of the wall correction factor for air kerma measurements using cylindrical cavity chambers

The dependence of the results of air kerma measurements on the orientation of the cylindrical cavity chamber used for beam standardizations is reexamined. The wall attenuation correction factors for the (60)Co and (136)Cs air kerma measurements were obtained for various irradiation angles by extrapolation of the dependences of experimental data and by Monte Carlo simulations. Applying the correction based on extrapolation does not provide an angle-invariant air kerma rate, as desired. In contrast, Monte Carlo simulations, which take into account various affecting phenomena, produce a wall correction factor that makes the corrected air kerma independent of the incidence angle.

Overview of secondary neutron production relevant to shielding in space

An overview of experimental secondary neutron measurements relevant to space-related activities is presented. Stopping target yields and cross section measurements conducted at particle accelerators using heavy ions with energies > 100 MeV per nucleon are discussed.