Observation of the effect of gravity on the motion of antimatter

Einstein's general theory of relativity from 19151 remains the most successful description of gravitation. From the 1919 solar eclipse2 to the observation of gravitational waves3, the theory has passed many crucial experimental tests. However, the evolving concepts of dark matter and dark energy illustrate that there is much to be learned about the gravitating content of the universe. Singularities in the general theory of relativity and the lack of a quantum theory of gravity suggest that our picture is incomplete. It is thus prudent to explore gravity in exotic physical systems. Antimatter was unknown to Einstein in 1915. Dirac's theory4 appeared in 1928; the positron was observed5 in 1932. There has since been much speculation about gravity and antimatter. The theoretical consensus is that any laboratory mass must be attracted6 by the Earth, although some authors have considered the cosmological consequences if antimatter should be repelled by matter7-10. In the general theory of relativity, the weak equivalence principle (WEP) requires that all masses react identically to gravity, independent of their internal structure. Here we show that antihydrogen atoms, released from magnetic confinement in the ALPHA-g apparatus, behave in a way consistent with gravitational attraction to the Earth. Repulsive 'antigravity' is ruled out in this case. This experiment paves the way for precision studies of the magnitude of the gravitational acceleration between anti-atoms and the Earth to test the WEP.

Development of a method of evaluating PuO2 particle diameters using an alpha-particle imaging detector

It is very important to evaluate the diameters (activity median aerodynamic diameter) of plutonium dioxide (PuO2) particles for internal exposure dose evaluation. In this study, a method of evaluating PuO2 particle diameters using an alpha-particle imaging detector was developed. PuO2 particles with different diameters were modeled by Monte Carlo simulation, and the change in the shape of the energy spectrum for each particle diameter was evaluated. Two different patterns were modeled, namely, the case of 239PuO2 and the case of PuO2 (including isotopic composition of Pu). Multiple regression analysis was performed to determine the PuO2 particle diameter from the obtained parameters. The simulated diameters and the diameters obtained with the regression model were in good agreement. The advantage of using the alpha-particle imaging detector is to measure the alpha energy spectrum for individual particle, and this allows accurate measurement of particle diameter distribution.

Sympathetic cooling of positrons to cryogenic temperatures for antihydrogen production

The positron, the antiparticle of the electron, predicted by Dirac in 1931 and discovered by Anderson in 1933, plays a key role in many scientific and everyday endeavours. Notably, the positron is a constituent of antihydrogen, the only long-lived neutral antimatter bound state that can currently be synthesized at low energy, presenting a prominent system for testing fundamental symmetries with high precision. Here, we report on the use of laser cooled Be+ ions to sympathetically cool a large and dense plasma of positrons to directly measured temperatures below 7 K in a Penning trap for antihydrogen synthesis. This will likely herald a significant increase in the amount of antihydrogen available for experimentation, thus facilitating further improvements in studies of fundamental symmetries.

Laser cooling of antihydrogen atoms

The photon-the quantum excitation of the electromagnetic field-is massless but carries momentum. A photon can therefore exert a force on an object upon collision1. Slowing the translational motion of atoms and ions by application of such a force2,3, known as laser cooling, was first demonstrated 40 years ago4,5. It revolutionized atomic physics over the following decades6-8, and it is now a workhorse in many fields, including studies on quantum degenerate gases, quantum information, atomic clocks and tests of fundamental physics. However, this technique has not yet been applied to antimatter. Here we demonstrate laser cooling of antihydrogen9, the antimatter atom consisting of an antiproton and a positron. By exciting the 1S-2P transition in antihydrogen with pulsed, narrow-linewidth, Lyman-α laser radiation10,11, we Doppler-cool a sample of magnetically trapped antihydrogen. Although we apply laser cooling in only one dimension, the trap couples the longitudinal and transverse motions of the anti-atoms, leading to cooling in all three dimensions. We observe a reduction in the median transverse energy by more than an order of magnitude-with a substantial fraction of the anti-atoms attaining submicroelectronvolt transverse kinetic energies. We also report the observation of the laser-driven 1S-2S transition in samples of laser-cooled antihydrogen atoms. The observed spectral line is approximately four times narrower than that obtained without laser cooling. The demonstration of laser cooling and its immediate application has far-reaching implications for antimatter studies. A more localized, denser and colder sample of antihydrogen will drastically improve spectroscopic11-13 and gravitational14 studies of antihydrogen in ongoing experiments. Furthermore, the demonstrated ability to manipulate the motion of antimatter atoms by laser light will potentially provide ground-breaking opportunities for future experiments, such as anti-atomic fountains, anti-atom interferometry and the creation of antimatter molecules.

Investigation of the fine structure of antihydrogen

At the historic Shelter Island Conference on the Foundations of Quantum Mechanics in 1947, Willis Lamb reported an unexpected feature in the fine structure of atomic hydrogen: a separation of the 2S1/2 and 2P1/2 states1. The observation of this separation, now known as the Lamb shift, marked an important event in the evolution of modern physics, inspiring others to develop the theory of quantum electrodynamics2-5. Quantum electrodynamics also describes antimatter, but it has only recently become possible to synthesize and trap atomic antimatter to probe its structure. Mirroring the historical development of quantum atomic physics in the twentieth century, modern measurements on anti-atoms represent a unique approach for testing quantum electrodynamics and the foundational symmetries of the standard model. Here we report measurements of the fine structure in the n = 2 states of antihydrogen, the antimatter counterpart of the hydrogen atom. Using optical excitation of the 1S-2P Lyman-α transitions in antihydrogen6, we determine their frequencies in a magnetic field of 1 tesla to a precision of 16 parts per billion. Assuming the standard Zeeman and hyperfine interactions, we infer the zero-field fine-structure splitting (2P1/2-2P3/2) in antihydrogen. The resulting value is consistent with the predictions of quantum electrodynamics to a precision of 2 per cent. Using our previously measured value of the 1S-2S transition frequency6,7, we find that the classic Lamb shift in antihydrogen (2S1/2-2P1/2 splitting at zero field) is consistent with theory at a level of 11 per cent. Our observations represent an important step towards precision measurements of the fine structure and the Lamb shift in the antihydrogen spectrum as tests of the charge-parity-time symmetry8 and towards the determination of other fundamental quantities, such as the antiproton charge radius9,10, in this antimatter system.

AN ACCIDENT OF INTERNAL CONTAMINATION WITH PLUTONIUM AND AMERICIUM AT A NUCLEAR FACILITY IN JAPAN: A PRELIMINARY REPORT AND THE POSSIBILITY OF DTPA ADMINISTRATION ADDING TO THE DIAGNOSIS

This article introduces the first accident of internal contamination with plutonium (Pu) or americium (Am) in Japan for which treatment was carried out. An accident of internal contamination with Pu and Am occurred at a Pu research facility at Oarai-town of Ibaraki prefecture in Japan. A plastic bag containing these radionuclides ruptured when five workers were inspecting a storage container in a hood. As a consequence, these workers were internally contaminated with Pu and Am. Although contamination on the body surface was observed in all five workers, a positive nasal swab was detected in only three of them. A chelating agent, calcium diethylenetriaminepenta-acetate (CaDTPA), was administered to all of them including the two workers without a positive nasal swab. However, bioassay detected a significant amount of Pu and Am in urine after administration of DTPA in these two workers, whereas the levels of these nuclides were below minimum detectable levels in urine before the administration. Since the prevalence of adverse reactions in DTPAs is low, the present results suggest that administration of DTPA can be used for the diagnosis of internal contamination even when a nasal swab is negative or contamination around body orifices is not detected.

Observation of the 1S-2P Lyman-α transition in antihydrogen

In 1906, Theodore Lyman discovered his eponymous series of transitions in the extreme-ultraviolet region of the atomic hydrogen spectrum1,2. The patterns in the hydrogen spectrum helped to establish the emerging theory of quantum mechanics, which we now know governs the world at the atomic scale. Since then, studies involving the Lyman-α line-the 1S-2P transition at a wavelength of 121.6 nanometres-have played an important part in physics and astronomy, as one of the most fundamental atomic transitions in the Universe. For example, this transition has long been used by astronomers studying the intergalactic medium and testing cosmological models via the so-called 'Lyman-α forest'3 of absorption lines at different redshifts. Here we report the observation of the Lyman-α transition in the antihydrogen atom, the antimatter counterpart of hydrogen. Using narrow-line-width, nanosecond-pulsed laser radiation, the 1S-2P transition was excited in magnetically trapped antihydrogen. The transition frequency at a field of 1.033 tesla was determined to be 2,466,051.7 ± 0.12 gigahertz (1σ uncertainty) and agrees with the prediction for hydrogen to a precision of 5 × 10-8. Comparisons of the properties of antihydrogen with those of its well-studied matter equivalent allow precision tests of fundamental symmetries between matter and antimatter. Alongside the ground-state hyperfine4,5 and 1S-2S transitions6,7 recently observed in antihydrogen, the Lyman-α transition will permit laser cooling of antihydrogen8,9, thus providing a cold and dense sample of anti-atoms for precision spectroscopy and gravity measurements10. In addition to the observation of this fundamental transition, this work represents both a decisive technological step towards laser cooling of antihydrogen, and the extension of antimatter spectroscopy to quantum states possessing orbital angular momentum.

Experiences of Population Monitoring Using Whole-Body Counters in Response to the Fukushima Nuclear Accident

Whole-body counter measurements of residents of Fukushima Prefecture have been extensively performed after the Fukushima Dai-ichi Nuclear Power Plant accident in March 2011. These measurements have demonstrated that the levels of internal contamination with radioactive cesium (Cs and Cs) in the residents are very low. This article provides an overview of and lessons learned from these whole-body counter measurements with emphasis on the technical problems encountered, and it discusses the effective use of whole-body counters for assessing the internal thyroid doses of individuals when direct measurements of I in the thyroid are difficult or impossible to implement for the total affected population in a short time after a nuclear reactor accident. The application of this dose reconstruction method requires determining the intake ratio of I to cesium isotopes at appropriate times and considers the short biological half-lives of cesium isotopes, in particular for children.

Characterization of the 1S-2S transition in antihydrogen

In 1928, Dirac published an equation 1 that combined quantum mechanics and special relativity. Negative-energy solutions to this equation, rather than being unphysical as initially thought, represented a class of hitherto unobserved and unimagined particles-antimatter. The existence of particles of antimatter was confirmed with the discovery of the positron 2 (or anti-electron) by Anderson in 1932, but it is still unknown why matter, rather than antimatter, survived after the Big Bang. As a result, experimental studies of antimatter3-7, including tests of fundamental symmetries such as charge-parity and charge-parity-time, and searches for evidence of primordial antimatter, such as antihelium nuclei, have high priority in contemporary physics research. The fundamental role of the hydrogen atom in the evolution of the Universe and in the historical development of our understanding of quantum physics makes its antimatter counterpart-the antihydrogen atom-of particular interest. Current standard-model physics requires that hydrogen and antihydrogen have the same energy levels and spectral lines. The laser-driven 1S-2S transition was recently observed 8 in antihydrogen. Here we characterize one of the hyperfine components of this transition using magnetically trapped atoms of antihydrogen and compare it to model calculations for hydrogen in our apparatus. We find that the shape of the spectral line agrees very well with that expected for hydrogen and that the resonance frequency agrees with that in hydrogen to about 5 kilohertz out of 2.5 × 1015 hertz. This is consistent with charge-parity-time invariance at a relative precision of 2 × 10-12-two orders of magnitude more precise than the previous determination 8 -corresponding to an absolute energy sensitivity of 2 × 10-20 GeV.

DEVELOPMENT OF A NEW DETECTOR SYSTEM TO EVALUATE POSITION AND ACTIVITY OF PLUTONIUM PARTICLES IN NASAL CAVITIES

Plutonium dioxide (PuO2) is used to fabricate a mixed oxide fuel for fast breeder reactors. When a glove box containing PuO2 fails, such as by rupture of a glove or a vinyl bag, airborne contamination of plutonium (Pu) can occur. If a worker inhales PuO2 particles, they will be continually irradiating their lung tissue with alpha particles, and this could cause lung cancer. The nasal smear and nose blow methods are useful for checking workers for PuO2 intake in the field. However, neither method can evaluate the quantitative activity of Pu. No alpha-particle detector that can be used for direct measurements in the nasal cavity has been developed. For direct and quantitative measurement, it is required that a shape of the detector should be a fine bar which inserts itself in the nose to measure the accurate activity of Pu. Therefore, we developed a nasal monitor capable of directly measuring the activity of Pu in the nasal cavity to estimate the internal exposure dose of a worker. Prismatic-shaped 2 × 2 acrylic light guides were used to compose a detector block, and a ZnS(Ag) scintillator was adhered to the surface of these light guides. Silicon photomultiplier (SiPM) arrays with 8 × 8 channels were used as a photodetector. Actual PuO2 particles were measured using the nasal monitor. The nasal monitor could be directly inserted in the nasal cavities, and the activity distribution of Pu was obtained by the nasal monitor. The average efficiencies in 4-pi were 11.4 and 11.6% for the left and right nasal cavities, respectively. The influence of gamma and beta rays from Cesium-137 (137Cs) Strontium-90 (90Sr) on the detection of the alpha particles of Pu was negligible. The difference in the measured Pu activity between the ZnS(Ag) scintillation counter and the nasal monitor was within 4.0%. Therefore, it was considered that the developed nasal monitor could be used in direct Pu determination to estimate the internal exposure dose of workers.

Erratum: Observation of the hyperfine spectrum of antihydrogen

This corrects the article DOI: 10.1038/nature23446.

Enhanced Control and Reproducibility of Non-Neutral Plasmas

The simultaneous control of the density and particle number of non-neutral plasmas confined in Penning-Malmberg traps is demonstrated. Control is achieved by setting the plasma's density by applying a rotating electric field while simultaneously fixing its axial potential via evaporative cooling. This novel method is particularly useful for stabilizing positron plasmas, as the procedures used to collect positrons from radioactive sources typically yield plasmas with variable densities and particle numbers; it also simplifies optimization studies that require plasma parameter scans. The reproducibility achieved by applying this technique to the positron and electron plasmas used by the ALPHA antihydrogen experiment at CERN, combined with other developments, contributed to a 10-fold increase in the antiatom trapping rate.

Observation of the hyperfine spectrum of antihydrogen

The observation of hyperfine structure in atomic hydrogen by Rabi and co-workers and the measurement of the zero-field ground-state splitting at the level of seven parts in 10¹³ are important achievements of mid-twentieth-century physics. The work that led to these achievements also provided the first evidence for the anomalous magnetic moment of the electron, inspired Schwinger's relativistic theory of quantum electrodynamics and gave rise to the hydrogen maser, which is a critical component of modern navigation, geo-positioning and very-long-baseline interferometry systems. Research at the Antiproton Decelerator at CERN by the ALPHA collaboration extends these enquiries into the antimatter sector. Recently, tools have been developed that enable studies of the hyperfine structure of antihydrogen-the antimatter counterpart of hydrogen. The goal of such studies is to search for any differences that might exist between this archetypal pair of atoms, and thereby to test the fundamental principles on which quantum field theory is constructed. Magnetic trapping of antihydrogen atoms provides a means of studying them by combining electromagnetic interaction with detection techniques that are unique to antimatter. Here we report the results of a microwave spectroscopy experiment in which we probe the response of antihydrogen over a controlled range of frequencies. The data reveal clear and distinct signatures of two allowed transitions, from which we obtain a direct, magnetic-field-independent measurement of the hyperfine splitting. From a set of trials involving 194 detected atoms, we determine a splitting of 1,420.4 ± 0.5 megahertz, consistent with expectations for atomic hydrogen at the level of four parts in 10⁴. This observation of the detailed behaviour of a quantum transition in an atom of antihydrogen exemplifies tests of fundamental symmetries such as charge-parity-time in antimatter, and the techniques developed here will enable more-precise such tests.

Antihydrogen accumulation for fundamental symmetry tests

Antihydrogen, a positron bound to an antiproton, is the simplest anti-atom. Its structure and properties are expected to mirror those of the hydrogen atom. Prospects for precision comparisons of the two, as tests of fundamental symmetries, are driving a vibrant programme of research. In this regard, a limiting factor in most experiments is the availability of large numbers of cold ground state antihydrogen atoms. Here, we describe how an improved synthesis process results in a maximum rate of 10.5 ± 0.6 atoms trapped and detected per cycle, corresponding to more than an order of magnitude improvement over previous work. Additionally, we demonstrate how detailed control of electron, positron and antiproton plasmas enables repeated formation and trapping of antihydrogen atoms, with the simultaneous retention of atoms produced in previous cycles. We report a record of 54 detected annihilation events from a single release of the trapped anti-atoms accumulated from five consecutive cycles.

Antihydrogen studies are important in testing the fundamental principles of physics but producing antihydrogen in large amounts is challenging. Here the authors demonstrate an efficient and high-precision method for trapping and stacking antihydrogen by using controlled plasma.

Early Intake of Radiocesium by Residents Living Near the TEPCO Fukushima Dai-Ichi Nuclear Power Plant after the Accident. Part 1: Internal Doses Based on Whole-body Measurements by NIRS

The Tokyo Electric Power Company's Fukushima Dai-ichi Nuclear Power Plant (FDNPP) accident in 2011 resulted in a release of radionuclides into the environment (I: 142.9 PBq, Cs:12.4 PBq). This study presents the results of internal doses to 174 residents living near the FDNPP at the time of the accident based on whole-body (WB) measurements performed by the National Institute of Radiological Sciences (NIRS) during the period between 27 June and 28 July 2011. The 174 subjects consisted of 125 adults (≥18-y) and 49 children (<18-y) and included 90 persons of Namie town, one of the municipalities heavily contaminated with the radionuclides. The number of subjects with significant detection of both Cs and Cs was relatively small: 28.8% for the adults and 4.1% for the children. A significant gender difference in the Cs detection rate (males > females) was observed in the adults but not the children. In this study, the committed effective dose (CED) from Cs and Cs was calculated based on individual WB contents (Cs) corrected against body size, the observed body content ratio of Cs to Cs, and the assumed intake scenario (namely, acute inhalation of Type F compounds on 12 March 2011 when the first explosive event occurred at the site of the FDNPP). The 90th-percentile CED value for the adults was around 0.1 mSv and the maximum CED (0.63 mSv) was found in an elderly male. Comparable CED results were obtained in other WB measurements subsequently performed by the Japan Atomic Energy Agency (JAEA) in a similar manner to that of the NIRS, suggesting that the contribution of ingestion to the WB content observed would be trivial for most of the JAEA subjects. The intake ratio of I to Cs was evaluated to be 3~5 based on the I thyroid measurement data of Tokonami et al. Using the average intake ratio of 3.8, the resulting median and maximum thyroid-equivalent doses to the adult subjects of this study were estimated at 3.5 mSv and 84 mSv, respectively.

APPLICATION OF AN IMAGING PLATE FOR EVALUATING THE UNCERTAINTY IN DIRECT ORGAN MEASUREMENTS DUE TO VARIATION IN DETECTOR LOCATION

In direct organ measurements, there can be uncertainty to the quantified amount of activity due to variations in detector locations. Here, the authors demonstrate a new use of an imaging plate (IP) for evaluating this uncertainty. The method requires only that an array of regions of interest (ROIs) is set on a latent image obtained from the IP; each ROI conforms to an active area of the detector to be used. In this study, the proposed method was tested in an experiment using a realistic torso phantom containing an (241)Am liver source. The latent image of this source was obtained by irradiating the IP (20 × 40 cm(2)) from the anterior surface of the phantom. A comparison of responses between the IP and a high-purity germanium detector was made for 6 of the 144 circular ROIs arranged on the latent image, showing excellent correlation between the two sets of measures. The dispersion of the photostimulated luminescence values of the 144 ROIs was found to be 8.2% (1σ) and 1.09 as a log-normal scattering factor, which was expected to be the same as the uncertainty of concern in the present measurement with the HPGe detector.

INTERNAL DOSES OF THREE PERSONS STAYING 110 KM SOUTH OF THE FUKUSHIMA DAIICHI NUCLEAR POWER STATION DURING THE ARRIVAL OF RADIOACTIVE PLUMES BASED ON DIRECT MEASUREMENTS

The authors describe the results of direct measurements made on three persons who stayed in Tokai-mura, a village located ∼110 km south of the Fukushima Daiichi Nuclear Power Station (FDNPS), during the arrival of significant radioactive plumes released from the FDNPS as a consequence of the Tohoku earthquake/tsunami/FDNPS accident in March 2011. These measurements were made using a NaI(Tl) spectrometer and a whole-body counter shortly after the accident. Their thyroid equivalent doses ((131)I) were estimated to be 0.9-1.4 mSv under the assumption of acute intake via inhalation on 15 March, when the first significant release event was observed. Although greatly depending on the physicochemical form of iodine, the intake amount ratios of (131)I to (137)Cs for the three subjects were calculated as 2.7-3.7, which were much smaller than the radioactivity ratio (7.8) found in air sampling at the same site.

Internal thyroid doses to Fukushima residents-estimation and issues remaining

Enormous quantities of radionuclides were released into the environment following the disastrous accident at the Fukushima Daiichi Nuclear Power Plant (FDNPP) in March 2011. It is of great importance to determine the exposure doses received by the populations living in the radiologically affected areas; however, there has been significant difficulty in estimating the internal thyroid dose received through the intake of short-lived radionuclides (mainly, (131)I), because of the lack of early measurements on people. An estimation by the National Institute of Radiological Sciences for 1 April 2012 to 31 March 2013 was thus performed using a combination of the following three sources: thyroid measurement data ((131)I) for 1080 children examined in the screening campaign, whole-body counter measurement data ((134)Cs, (137)Cs) for 3000 adults, and atmospheric transport dispersion model simulations. In this study, the residents of Futaba town, Iitate village and Iwaki city were shown to have the highest thyroid equivalent dose, and their doses were estimated to be mostly below 30 mSv. However, this result involved a lot of uncertainties and provided only representative values for the residents. The present paper outlines a more recent dose estimation and preliminary analyses of personal behavior data used in the new method.

Knee extension strength and post-operative functional prediction in quadriceps resection for soft-tissue sarcoma of the thigh

Objectives

Our objective was to predict the knee extension strength and post-operative function in quadriceps resection for soft-tissue sarcoma of the thigh.

Methods

A total of 18 patients (14 men, four women) underwent total or partial quadriceps resection for soft-tissue sarcoma of the thigh between 2002 and 2014. The number of resected quadriceps was surveyed, knee extension strength was measured with the Biodex isokinetic dynamometer system (affected side/unaffected side) and relationships between these were examined. The Musculoskeletal Tumor Society (MSTS) score, Toronto Extremity Salvage Score (TESS), European Quality of Life-5 Dimensions (EQ-5D) score and the Short Form 8 were used to evaluate post-operative function and examine correlations with extension strength. The cutoff value for extension strength to expect good post-operative function was also calculated using a receiver operating characteristic (ROC) curve and Fisher’s exact test.

Results

Extension strength decreased when the number of resected quadriceps increased (p < 0.001), and was associated with lower MSTS score, TESS and EQ-5D (p = 0.004, p = 0.005, p = 0.006, respectively). Based on the functional evaluation scales, the cutoff value of extension strength was 56.2%, the equivalent to muscle strength with resection of up to two muscles.

Conclusion

Good post-operative results can be expected if at least two quadriceps muscles are preserved.

Cite this article: A. Tanaka, Y. Yoshimura, K. Aoki, M. Kito, M. Okamoto, S. Suzuki, T. Momose, H. Kato. Knee extension strength and post-operative functional prediction in quadriceps resection for soft-tissue sarcoma of the thigh. Bone Joint Res 2016;5:232–238. DOI: 10.1302/2046-3758.56.2000631.

Periodontal tissue engineering by nano beta-tricalcium phosphate scaffold and fibroblast growth factor-2 in one-wall infrabony defects of dogs

BACKGROUND AND OBJECTIVE

Nanoparticle bioceramics are being investigated for biomedical applications. We fabricated a regenerative scaffold comprising type I collagen and beta-tricalcium phosphate (β-TCP) nanoparticles. Fibroblast growth factor-2 (FGF-2) is a bioeffective signaling molecule that stimulates cell proliferation and wound healing. This study examined the effects, on bioactivity, of a nano-β-TCP/collagen scaffold loaded with FGF-2, particularly on periodontal tissue wound healing.

MATERIAL AND METHODS

Beta-tricalcium phosphate was pulverized into nanosize particles (84 nm) and was then dispersed. A nano-β-TCP scaffold was prepared by coating the surface of a collagen scaffold with a nanosize β-TCP dispersion. Scaffolds were characterized using scanning electron microscopy, compressive testing, cell seeding and rat subcutaneous implant testing. Then, nano-β-TCP scaffold, nano-β-TCP scaffold loaded with FGF-2 and noncoated collagen scaffold were implanted into a dog one-wall infrabony defect model. Histological observations were made at 10 d and 4 wk postsurgery.

RESULTS

Scanning electron microscopy images show that TCP nanoparticles were attached to collagen fibers. The nano-β-TCP scaffold showed higher compressive strength and cytocompatibility compared with the noncoated collagen scaffold. Rat subcutaneous implant tests showed that the DNA contents of infiltrating cells in the nano-β-TCP scaffold and the FGF-2-loaded scaffold were approximately 2.8-fold and 3.7-fold greater, respectively, than in the collagen scaffold. Histological samples from the periodontal defect model showed about five-fold greater periodontal tissue repair following implantation of the nano-β-TCP scaffold loaded with FGF-2 compared with the collagen scaffold.

CONCLUSION

The β-TCP nanoparticle coating strongly improved the collagen scaffold bioactivity. Nano-β-TCP scaffolds containing FGF-2 are anticipated for use in periodontal tissue engineering.

Clinical outcome of deep-seated atypical lipomatous tumor of the extremities with median-term follow-up study

AIMS

There is no consensus on the best surgical treatment for deep-seated atypical lipomatous tumor (ALT) of the extremities; furthermore, the appropriate duration for follow-up observation remains unclear. We investigated clinical and functional median-term outcomes in the primary operations for ALT of the extremities in order to find its best treatment methods and observation periods.

METHODS

From 1996 to 2009, we diagnosed 41 patients with deep-seated ALT of the extremities. Wide resection was performed on 11 patients and marginal resection was performed on 30 patients. The minimum follow-up was 5 years (median, 8.5; range, 5-17.4). Patients were evaluated for their local recurrence, dedifferentiation, and post-operative function using the ISOLS/MSTS scoring system.

RESULTS

Recurrence and dedifferentiation rates were both 0% for the wide resection group, while the rates were 23% (7/30) and 3% (1/30) for the marginal resection group, respectively. Median duration before recurrence was 7.2 years (range, 4.0-14.2). Local recurrence-free survival rate was significantly higher in the wide resection group (P = 0.013). In the marginal resection group, 10% (3/30) of the cases showed residual tumor. The localization of these tumors was all intermuscular. The ISOLS/MSTS scores were 98% (range, 90-100) for wide resection and 99% (range, 93-100) for marginal resection, with no statistical difference (P = 0.694). No ALT-related deaths occurred during the observation period.

CONCLUSIONS

In addition to long-term (at least 8 years) of continuous observation, a wide resection is necessary in order to prevent recurrence, dedifferentiation, and residual tumor.

Estimation of internal exposure of the thyroid to (131)I on the basis of (134)Cs accumulated in the body among evacuees of the Fukushima Daiichi Nuclear Power Station accident

Namie Town was heavily contaminated by the Fukushima Daiichi Nuclear Power Station accident. The thyroid equivalent dose for residents who lived in Namie was estimated using results of whole body counting examinations which were carried out by the Japan Atomic Energy Agency a few months after the nuclear accident. Photon peaks of (131)I and (134)Cs were previously measured by the authors using a NaI(Tl) scintillation spectrometer and that information was used to estimate the (131)I/(134)Cs activity ratio of total intake in the present study. The maximum values of (131)I/(134)Cs activity ratio corresponding to thyroid uptake factors of 0.3, 0.1 and 0.03 were evaluated to be 0.9, 2.6 and 8.7, respectively. The maximum value of the (131)I/(134)Cs activity ratio was used to obtain the most conservative thyroid equivalent dose estimation. The maximum internal exposure of the thyroid to (131)I on the basis of (134)Cs accumulated in the body measured by the whole body counter was estimated to be 18mSv. This value was much smaller than 50mSv that the International Atomic Energy Agency recommends as the dose at which exposed persons should take stable iodine tablets.

Development of new analytical method based on beta-alpha coincidence method for selective measurement of 214Bi-214Po-application to dust filter used in radiation management

The radionuclide pair (214)Bi and (214)Po which belongs to the uranium series interferes with airborne radionuclide measurement needed for the radiation management of a nuclear facility. Time intervals between (214)Bi (β) and (214)Po (α) are much shorter than artificial radionuclides due to the short half-life of (214)Po (164 μs). The purpose of this study is to develop of a new analytical method (time interval analysis: TIA) based on the beta-alpha coincidence method for selective measurement of (214)Bi-(214)Po. The developed method was applied to an actual dust-filter measurement. The TIA system was highly effective in measuring of the filter with background subtraction.

Development of a microcalorimeter with transition edge sensor for detection of LX rays emitted by transuranium elements

A transition edge sensor (TES) microcalorimeter has been developed for use as an energy dispersive X-ray spectrometer. The TES microcalorimeter is a thermal detector that enables one to determine the energy of an incident photon by measuring the resultant increase in temperature. In this work, a Ti/Au TES microcalorimeter was developed to measure LX rays emitted by transuranium elements. The phase transition temperature was set at ~200 mK by using a bilayer structure composed of a 110-nm-thick Au layer and a 40-nm-thick Ti layer. An Au of 5 µm thickness was deposited on the Ti/Au bilayer to achieve an absorption efficiency of 35-80 % for the energy range of LX rays (10-25 keV). The developed TES microcalorimeter was irradiated with LX rays emitted by an (241)Am source at an operating temperature of 140 mK. An energy resolution of ~80 eV (full width at the half maximum) was obtained for L(β1)X ray of 17.75 keV.

Radiation protection at nuclear fuel cycle facilities

Radiation protection methodologies concerning individual monitoring, workplace monitoring and environmental monitoring in nuclear fuel facilities have been developed and applied to facilities in the Nuclear Fuel Cycle Engineering Laboratories (NCL) of Japan Atomic Energy Agency (JAEA) for over 40 y. External exposure to photon, beta ray and neutron and internal exposure to alpha emitter are important issues for radiation protection at these facilities. Monitoring of airborne and surface contamination by alpha and beta/photon emitters at workplace is also essential to avoid internal exposure. A critical accident alarm system developed by JAEA has been proved through application at the facilities for a long time. A centralised area monitoring system is effective for emergency situations. Air and liquid effluents from facilities are monitored by continuous monitors or sampling methods to comply with regulations. Effluent monitoring has been carried out for 40 y to assess the radiological impacts on the public and the environment due to plant operation.

Carpal tunnel pressure measurement during two-portal endoscopic carpal tunnel release

BACKGROUND

Although there remain concerns of median nerve damage during endoscopic carpal tunnel release for carpal tunnel syndrome, carpal tunnel pressure variations during Chow's two-portal technique have not been well investigated.

METHODS

We performed a modified two-portal endoscopic carpal tunnel release on 30 patients by inserting a catheter pressure transducer into the carpal tunnel for continuous pressure measurement during the procedure. Grip and pinch strengths, Semmes-Weinstein monofilament test, and nerve conduction studies were examined preoperatively and at postoperative 1, 3, and 6 months. Numbness and the Disabilities of the Arm, Shoulder and Hand score were also evaluated pre and postoperatively.

FINDINGS

Subjective symptoms and nerve conduction study findings improved uneventfully. The pressure was always observed to be maximum pressure immediately before the cannula was withdrawn from the exit portal, and carpal tunnel pressure >300 mm Hg was recorded in most of the patients.

INTERPRETATION

A transient increase in the carpal tunnel pressure occurred in all the patients; however, it did not correlate with their clinical outcome or with increased risk of peri-operative complications. Since time-pressure threshold of the median nerve during endoscopic carpal tunnel release is still unknown, our results did not guarantee its safety.

FDG-PET in T-cell and NK-cell neoplasms

BACKGROUND

A growing number of studies demonstrate the utility of (18)fluoro-2-deoxyglucose positron emission tomography (FDG-PET) in the management of malignant lymphoma. The results of FDG-PET, however, have not been studied extensively for T-cell and natural killer (NK)-cell neoplasms.

PATIENTS AND METHODS

We retrospectively evaluated pretreatment FDG-PET scans in 41 patients with T/NK-cell neoplasms diagnosed according to the World Health Organization (WHO) classification. Histological subtypes frequently included were peripheral T-cell lymphoma, unspecified (PTCLu, n = 11), extranodal NK/T-cell lymphoma, nasal type (ENKL, n = 8), primary cutaneous anaplastic large cell lymphoma (C-ALCL, n = 5), and angioimmunoblastic T-cell lymphoma (AILT, n = 4).

RESULTS

FDG-PET detected a lymphoma lesion in at least one site in 36 out of 41 patients. The positive rate was equally high in most histological subtypes except for cutaneous lymphomas: PTCLu 91%, ENKL 100%, C-ALCL 60%, AILT 100%. All the patients without an FDG-avid lesion had lesions restricted to skin. Among patients who had cutaneous lesions, only 50% had FDG-avid cutaneous lesions, all of which were tumorous. The positive rate of FDG-PET for bone marrow involvement was only 20%.

CONCLUSION

T/NK-cell neoplasms incorporated in this study were generally FDG-avid except for cutaneous lesions and bone marrow involvement.

Development of 241Am lung monitoring system using an imaging plate

A new 241Am lung monitoring system without shielding was devised by using an imaging plate system. The Lawrence Livermore National Laboratory's realistic torso phantom containing a 241Am lung was covered by imaging plates sealed in lightproof bags. The imaging plate system displayed 241Am lung images characteristic of the lung shape of the torso phantom. The imaging plate system's lower detection limits of 14 Bq for 60 min exposure and 6 Bq for 300 min were the same levels as those of the phoswich detectors and the germanium detectors placed in shielded rooms. The imaging plate system for 60 min exposure detected about 2% of the annual limit of 740 Bq for 241Am inhalation. A lung monitoring system using imaging plates is applicable for 241Am lung monitoring.

RCA/IAEA third external dosimetry intercomparisons in East Asia region

Several intercomparison exercises were organised by the International Atomic Energy Agency (IAEA) on the determination of operational quantities at the regional or interregional basis. In East Asia region, a third phase of the intercomparison finished in mid 2004. It was organised within the frame of the Regional Cooperation Agreement (RCA) as a follow-up to previous exercises carried out during 1990-1992 and 1995-1996. The results of this intercomparison for the determination of operational quantities were satisfactory for all Member States. The laboratories demonstrated a good performance in quantities tested. The purpose of this paper is to present the results of the RCA/IAEA intercomparison and the future of RCA activities in support of assessment of occupational exposure by organising intercomparison runs.

Operational comparison of TLD albedo dosemeters and solid state nuclear tracks detectors in fuel fabrication facilities

The authors carried out an operational study that compared the use of TLD albedo dosemeters and solid state nuclear tracks detector in plutonium environments of Japan Nuclear Cycle Development Institute, Tokai Works. A selected group of workers engaged in the fabrication process of MOX (Plutonium-Uranium mixed oxide) fuel wore both TLD albedo dosemeters and solid state nuclear tracks detectors. The TL readings were generally proportional to the counted etch-pits, and thus the dose equivalent results obtained from TLD albedo dosemeter agreed with those from solid state nuclear tracks detector within a factor of 1.5. This result indicates that, in the workplaces of the MOX fuel plants, the neutron spectrum remained almost constant in terms of time and space, and the appropriate range of field-specific correction with spectrum variations was small in albedo dosimetry.

Calculations of anisotropy factors for radionuclide neutron sources due to scattering from source encapsulation and support structures

A model has been developed for calculating the angular neutron fluence distributions for radionuclide neutron sources that are heavily encapsulated or surrounded by source support structures as a source holder and a source movement system. These structures may cause an anisotropic neutron fluence distribution. This should be taken into account in the neutron-measuring instruments calibration procedure. The calculations were made for two types of widely used neutron sources, (241)Am-Be and (252)Cf, by combining an in-house code simulating the (9)Be(alpha,n) reactions and the Monte Carlo code MCNP-4C. As a result, anisotropy factors in the direction perpendicular to the source capsule axis for bare neutron sources were evaluated to be 1.012, 1.030 and 1.039 for (252)Cf in a standard Amersham X1 capsule, (241)Am-Be in a X3 capsule and (241)Am-Be in a X4 capsule, respectively. These values are in reasonable agreement with the published data. If the support structures are included in the MCNP simulation, the anisotropy factors for these neutron sources increase by approximately 10%.

Development of a neutron personal dose equivalent detector

A new neutron-measuring instrument that is intended to measure a neutron personal dose equivalent, H(p)(10) was developed. This instrument is composed of two parts: (1) a conventional moderator-based neutron dose equivalent meter and (2) a neutron shield made of borated polyethylene, which covers a backward hemisphere to adjust the angular dependence. The whole design was determined on the basis of MCNP calculations so as to have response characteristics that would generally match both the energy and angular dependencies of H(p)(10). This new instrument will be a great help in assessing the reference values of neutron H(p)(10) during field testing of personal neutron dosemeters in workplaces and also in interpreting their readings.

Practical action levels for chelation therapy in plutonium inhalation using nose swab

The aim of this study is to propose action levels for chelation therapy in the case of inhalation of plutonium compounds using nose swabs. The relationship between the activity found in the nose swabs and early faecal excretion was investigated using actual cases at JAEA-NFCEL. The ratio was found to be in log-normal distribution. The action levels based on the activity of nose swab corresponding to 10 ALI (=200 mSv) are determined for the facilities at JAEA-NFCEL by using the relationship and specific information such as isotopic ratio and physicochemical characteristics of plutonium compounds.

Reduced vascular reserve measured by stressed single photon emission computed tomography carries a high risk for stroke in patients with carotid stenosis

AIM

A few studies have observed reduced vascular reserve measured by single photon emission computed tomography (SPECT) to be a risk factor for stroke in patients with carotid artery occlusion, but stenosis has been excluded from these former studies. This study has evaluated the prognosis of reduced vascular reserve in patients with stenosis, and the effect of carotid endarterectomy (CEA) on these patients.

METHODS

Forty patients diagnosed as having >70% stenosis of the carotid artery at the University of Tokyo Hospital, between 2001 and 2004, underwent acetazolamide-stress SPECT test first. A resting SPECT study was performed on a different day from the stressed SPECT study. The patients were grouped as having reduced vascular reserve or normal vascular reserve from the SPECT results. Analysis of risk factors and the stroke-free curve analysis for reduced vascular reserve was performed.

RESULTS

Of the 40 patients, 24 (60%) had reduced vascular reserve and 18 underwent CEA. The mean follow-up period was 21.5+/-15.5 months (mean+/-SD). Four strokes occurred during follow-up: in 1 patient with CEA and 3 without CEA. All stroke patients had reduced vascular reserve. The patients with reduced vascular reserve without any surgery had a significantly lower stroke-free rate compared with those with normal vascular reserve or reduced vascular reserve, but also receiving CEA.

CONCLUSIONS

We propose performing SPECT tests in patients with severe carotid stenosis regardless of symptoms, and performing CEA on those with a reduction in vascular reserve.

Contralateral stenosis as a risk factor for carotid endarterectomy measured by near infrared spectroscopy

AIM

It is still controversial whether the existence of a contralateral stenosis is a risk factor during carotid endarterectomy (CEA). We used a near infrared spectroscopy (NIRS) monitoring system during CEA to evaluate the hemodynamic effect of contralateral stenosis during cross clamping of the carotid arteries.

METHODS

We monitored 34 consecutive cases of CEA, using NIRS. Tissue oxygen index (TOI), as a parameter of oxygenation, and total hemoglobin index (THI), as a parameter of blood volume, were measured during cross-clamping the carotid arteries. We evaluated the relationship between these results and the pre- and intraoperative characteristics including the existence of a contralateral stenosis and the results of single-photon emission computed tomography (SPECT).

RESULTS

Bilateral TOI and THI correlated well with the severity of the stenosis of the contralateral internal carotid artery, and ipsilateral THI correlated with the cerebrovascular reserve measured by SPECT.

CONCLUSIONS

A contralateral stenosis is a risk factor for CEA from the hemodynamical point of view, and extreme care should be taken when performing CEA in patients with bilateral stenoses.

Transgenic planarian lines obtained by electroporation using transposon-derived vectors and an eye-specific GFP marker

To generate transgenic planarians we used a set of versatile vectors for animal transgenesis based on the promiscuous transposons, mariner, Hermes and piggyBac, and a universal enhanced GFP (EGFP) marker system with three Pax6 dimeric binding sites, the 3xP3-EGFP developed by Berghammer et al. [Berghammer, A. J., Klinger, M. & Wimmer, E. A. (1999) Nature 402, 370-371]. This marker is expressed specifically in the eyes of various arthropod taxa. Upon microinjection into the parenchyma of adult planarians and subsequent electroporation, these vectors transpose efficiently into the planarian genome. One of the cell types transformed are the totipotent "neoblast" stem cells present in the adults, representing 30% of total cells. The neoblast represents a unique cell type with the capacity to proliferate and to differentiate into all somatic cell types as well as into germ cells. All three transposon vectors have high transformation efficiency, but only Hermes and piggyBac show stable integration. The mariner vector is frequently lost presumably because of the presence of active mariner-type transposons in the genome of the Girardia tigrina. Transformed animals are mosaics containing both transformed and untransformed neoblasts. These differentiate to form EGFP-positive and -negative photoreceptor cells. Such mosaicism is maintained through several cycles of regeneration induced by decapitation or asexual reproduction. Transformed neoblasts also contribute to the germ line, and can give rise to pure transgenic planarian lines in which EGFP is expressed in all photoreceptor cells after sexual reproduction. The presence of the transgenes was confirmed by PCR, plasmid rescue assay, inverse PCR, and Southern blotting. Our results with the 3xP3-EGFP marker confirm the presence of Pax6 activity in the differentiated photoreceptor cells of planarian eyes. Transgenesis will be an important tool to dissect developmental molecular mechanisms in planarian regeneration, development and stem cell biology, and may also be an entry point to analyze the biology of parasitic Platyhelminthes.

Dimensions of temperament as vulnerability factors in depression

In order to evaluate the hypothesis that one set of genetic risk factors may be common to disorders and dimensions of temperament, whereas environmental risk factors are disorder specific, we have conducted a genetic analysis of dimensions of temperament and symptoms of depression in about 201 pairs of monozygotic and dizygotic twins. Dimensions of temperament associated with novelty seeking, harm avoidance, reward dependence, and persistence were measured by using the Temperament and Character Instruments developed by Cloninger, and depressive symptoms were measured using the Hospital Anxiety and Depression Scale. Differences among individuals on these measures can be explained by differences in their genes and in their environmental experiences. There are no differences between the sexes in gene action affecting temperament. Each dimension of temperament is genetically dependent, and genetic variations in symptoms of depression are largely dependent on the same factors that affect the temperament. Temperament is closely associated with vulnerability to depressive symptoms.

Hemiparkinsonism associated with a mesencephalic tumor

A 66-year-old woman presented with a 3-year history of progressive right-sided hemiparkinsonism manifested by a right-hand resting tremor and right-sided bradykinesia. Magnetic resonance imaging (MRI) of the brain revealed a non-enhanced polycystic mass in the left midbrain. (11)C-methylspiperone ((11)C-NMSP) and (18)F-fluorodopa ((18)F-DOPA) positron emission tomography (PET) revealed a striatal hypometabolism that was restricted to the left side. These findings are consistent with a dysfunction in the left nigrostriatal dopaminergic pathway that is presumably induced by the cystic mass in the left midbrain. This case is significant due to the paucity of reports regarding the occurrence of a relatively pure parkinsonism that is associated with a mesencephalic space-occupying lesion.

Early faecal excretion of inhaled plutonium

Special individual monitoring has been performed for suspected cases of inhalation of plutonium at the Tokai Works of the Japan Nuclear Cycle Development Institute (JNC). Some experimental data obtained from this special individual monitoring during the past 20 years are presented and discussed in this paper. Our experience suggests the following conclusions. The daily plutonium excretion rate, normalised to the total excretion for the first 5 days after inhalation, was approximately in agreement with the latest ICRP 78 dosimetric model. Maximum faccal excretion is observed on the second day after inhalation of plutonium compounds. On the other hand, the activity ratio for total alpha activity observed in early faeces to that detected in nasal swabs showed a wide distribution range, and it was proven that variations in this ratio followed a log-normal distribution. The logarithmic mean probability is about 2.1 for PuO2 and about 15.7 for Pu(NO3)4. In practice, a conservative dose assessment from nasal swabs can be performed on the basis of these experimental ratios.

Anticholinergic drugs: response of parkinsonism not responsive to levodopa

A 41 year old man with parkinsonism and pyramidal signs is described. He was non-responsive to levodopa and dopamine receptor agonists but dramatically responded to trihexyphenidyl. In this patient, brain MRI showed bilateral hyperintensities along the corticospinal tracts on T2 weighted images. PET studies showed a decrease in (18)F-6-fluorodopa uptake in the putamen contralateral to the more affected limbs and normal D(2) receptor binding in the putamen. The PET and MRI findings and responsiveness to antiparkinsonian agents suggested degeneration of nigrostriatal dopaminergic neurons, striatal output pathways, and corticospinal tracts.

Suture techniques with high breaking strength and low gliding resistance: experiments in the dog flexor digitorum profundus tendon

We studied the breaking strength and gliding resistance between the pulley and flexor tendon for various suture techniques. Canine flexor digitorum profundus tendons were transected and sutured using one of eight repair techniques: modified Kessler (MK); Tsuge (Tsuge); two variations of a double modified Kessler (DK1, DK2); combined modified Kessler-modified Tsuge (MKT); augmented Becker (Becker); Cruciate (Cruciate); and modified double Tsuge (DT). The force to produce a 1.5 mm gap, ultimate failure load, resistance to gap formation, and gliding resistance were measured. The force to produce a 1.5 mm gap and the ultimate breaking force were higher with the DK1, DK2, MKT, Becker, Cruciate, and DT repairs than they were with the MK and Tsuge repair, while the gliding resistance of the Becker was higher than that of the MK, DK1, DK2, MKT. Cruciate, and UT repairs. In addition to confirming that repair strength increases as the number of strands crossing the repair increases, we also found that these stronger repairs need not produce higher gliding resistance than less robust repairs.

The effect of suture technique on adhesion formation after flexor tendon repair for partial lacerations in a canine model

BACKGROUND

Adhesion formation is a serious problem after flexor tendon repair. Many repair techniques have been developed to increase the suture strength after tendon repair surgery. The purpose of this study was to assess adhesion formation with different suture techniques in an in vivo canine model.

METHODS

Sixty flexor digitorum profundus tendons were partially lacerated (80%) and repaired with either a modified Kessler (MK) or Becker (MGH) suture technique and supplemented with a simple running suture. The dogs were sacrificed at 1 week, 3 weeks, or 6 weeks after surgery and the repaired tendons were evaluated for adhesion breaking strength.

RESULTS

At 1 week there was no significant difference between the two repair groups (p > 0.05). At 3 and 6 weeks, the adhesion breaking strength in the MK suture group was significantly less than that of the MGH suture group (p < 0.05).

CONCLUSION

High friction suture techniques may cause more adhesion formation than the lower friction suture techniques under passive postoperative therapy.