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Isa K, Oka K, Beauchamp N, Sato M, Wada K, Ohtani K, Nakanishi S, McCartney E, Tanaka M, Shimizu T, Kamiya S, Kruger C, Takahashi M. Safety assessment of the Clostridium butyricum MIYAIRI 588® probiotic strain including evaluation of antimicrobial sensitivity and presence of Clostridium toxin genes in vitro and teratogenicity in vivo. Hum Exp Toxicol 2016; 35:818-32. [DOI: 10.1177/0960327115607372] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Probiotics are live microorganisms ingested for the purpose of conferring a health benefit on the host. Development of new probiotics includes the need for safety evaluations that should consider factors such as pathogenicity, infectivity, virulence factors, toxicity, and metabolic activity. Clostridium butyricum MIYAIRI 588® (CBM 588®), an anaerobic spore-forming bacterium, has been developed as a probiotic for use by humans and food animals. Safety studies of this probiotic strain have been conducted and include assessment of antimicrobial sensitivity, documentation of the lack of Clostridium toxin genes, and evaluation of CBM 588® on reproductive and developmental toxicity in a rodent model. With the exception of aminoglycosides, to which anaerobes are intrinsically resistant, CBM 588® showed sensitivity to all antibiotic classes important in human and animal therapeutics. In addition, analysis of the CBM 588® genome established the absence of genes for encoding for α, β, or ε toxins and botulin neurotoxins types A, B, E, or F. There were no deleterious reproductive and developmental effects observed in mice associated with the administration of CBM 588®. These data provide further support for the safety of CBM 588® for use as a probiotic in animals and humans.
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Nagata C, Konish K, Tamura T, Wada K, Hayashi M, Takeda N, Yasuda K. Skin pigmentation is inversely associated with insulin resistance in healthy Japanese women. DIABETES & METABOLISM 2016; 42:368-371. [PMID: 27161346 DOI: 10.1016/j.diabet.2016.04.001] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/09/2016] [Revised: 03/30/2016] [Accepted: 04/01/2016] [Indexed: 10/21/2022]
Abstract
AIM As a low-pigment skin type is prevalent in men and women with type 1 diabetes, it is possible that skin pigmentation may be associated with insulin resistance. This study aimed to cross-sectionally examine this association in healthy women. METHODS Study participants were 792 Japanese women who attended a health examination and were not taking any medication for diabetes. Skin pigmentation on the inner upper and lower arms and forehead was measured using a Mexameter® skin colorimeter, a narrow-band reflective spectrophotometer. Data are expressed as a melanin index, which quantifies melanin content. Fasting blood glucose and insulin levels were also measured, and homoeostasis model assessment for insulin resistance (HOMA-IR) scores were calculated. Information on medical history and lifestyle factors were obtained by a self-administered questionnaire, while data on sun exposure were collected through interviews. Plasma 25-hydroxyvitamin D levels were measured in a subsample of women (n=464). RESULTS Melanin indices at the inner upper and lower arms were significantly and inversely associated with fasting insulin levels and HOMA-IR after controlling for age, body mass index, smoking status, indicators for rater effects, cumulative sun exposure and season at the time of measurement. Additional adjustment for plasma 25-hydroxyvitamin D levels did not alter the results. CONCLUSION These data suggest that skin pigmentation is associated with insulin resistance, and encourage future studies into the potential role of melanin and related factors in glucose homoeostasis.
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Watanabe T, Seguchi O, Yanase M, Fujita T, Sato T, Sunami H, Nakajima S, Nishimura K, Hisamatsu E, Kuroda K, Okada N, Wada K, Hata H, Ishibashi-Ueda H, Miyamoto Y, Kobayashi J, Fukushima N, Nakatani T. Relationship Between Brachial Artery Flow-Mediated Dilation and Clinical Characteristics of Heart Transplant Recipients. J Heart Lung Transplant 2016. [DOI: 10.1016/j.healun.2016.01.578] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
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Shimizu Y, Mori E, Wada K, Otori N, Kojima H. Airway intervention in cases of acute epiglottitis. B-ENT 2016; 12:279-284. [PMID: 29709131] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/08/2023] Open
Abstract
UNLABELLED Airway intervention in cases of acute epiglottitis.Problem/objectives: In cases of acute epiglottitis, indications for airway intervention have not been established. In the present study, we reviewed patients with acute epiglottitis to identify clinical factors, which suggest airway intervention should be performed. METHODOLOGY Patients with acute epiglottitis admitted to The Jikei University Daisan Hospital (Tokyo) from 2004 to 2013 were identified. Patients' characteristics, histories, laryngoscopic findings and laboratory findings were reviewed and analysed. RESULTS Of the 83 patients (82 adults and one adolescent) in the sample, 16 (19%) underwent airway intervention and conservative treatment. The factors that were significantly more likely to have been present in patients who received airway intervention were odynophagia, drooling, hoarseness, muffled voice, dyspnoea, swelling of the posterior side of the epiglottis, less than 50% of the glottis area being visible with laryngoscopy, and a high white blood cell (WBC) count. The only factor that was shown by multiple logistic regression analysis to be distinctively predictive of airway intervention was "less than 50% of the glottis area being visible" (P = .000, odds ratio = 23.630, sensitivity = 86.6%, specificity = 78.6%, predictive accuracy = 85.2%). CONCLUSIONS When considering whether airway intervention should be performed in cases of acute epiglottitis, the most important clinical factor is the laryngoscopic finding that "less than 50% of the glottis area being visible." Other important clinical factors to consider are odynophagia, drooling, hoarseness, muffled voice, dyspnoea, swelling of the posterior side of the epiglottis and a high WBC count.
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Mochizuki I, Ariga H, Fukaya Y, Wada K, Maekawa M, Kawasuso A, Shidara T, Asakura K, Hyodo T. Structure determination of the rutile-TiO2(110)-(1 × 2) surface using total-reflection high-energy positron diffraction (TRHEPD). Phys Chem Chem Phys 2016; 18:7085-92. [DOI: 10.1039/c5cp07892j] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
Detailed structure of the rutile-TiO2(110)-(1 × 2) has been determined using the newly developed technique of total-reflection high-energy positron diffraction (TRHEPD).
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Wang C, Yatsuya H, Tamakoshi K, Toyoshima H, Wada K, Li Y, Hilawe EH, Uemura M, Chiang C, Zhang Y, Aoyama A. Association of Parental History of Diabetes Mellitus with the Offspring's Incidence is Modified by Offspring's Body Weight, Findings from a Japanese Worksite-Based Cohort. Int J Epidemiol 2015. [DOI: 10.1093/ije/dyv096.139] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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Nakajima K, Teramoto T, Akagi H, Fujikawa T, Majima T, Minemoto S, Ogawa K, Sakai H, Togashi T, Tono K, Tsuru S, Wada K, Yabashi M, Yagishita A. Photoelectron diffraction from laser-aligned molecules with X-ray free-electron laser pulses. Sci Rep 2015; 5:14065. [PMID: 26369428 PMCID: PMC4570188 DOI: 10.1038/srep14065] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2014] [Accepted: 08/17/2015] [Indexed: 11/16/2022] Open
Abstract
We report on the measurement of deep inner-shell 2p X-ray photoelectron diffraction (XPD) patterns from laser-aligned I2 molecules using X-ray free-electron laser (XFEL) pulses. The XPD patterns of the I2 molecules, aligned parallel to the polarization vector of the XFEL, were well matched with our theoretical calculations. Further, we propose a criterion for applying our molecular-structure-determination methodology to the experimental XPD data. In turn, we have demonstrated that this approach is a significant step toward the time-resolved imaging of molecular structures.
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Wada K, Miyashin M. New techniques for producing aesthetic, direct full-crown composite resin restorations for primary molars: a 24-month follow-up study of eight cases. EUROPEAN JOURNAL OF PAEDIATRIC DENTISTRY 2015; 16:205-209. [PMID: 26418923] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
AIM Although the demand for aesthetic restoration of primary molars has increased, techniques for producing aesthetic, direct full-crown restorations using light-cured composite resin for primary molars and the associated clinical outcome are not well established. The aim of this study was to describe the use of new techniques to produce aesthetic, direct full-crown restorations using light-cured composite resin for primary molars. The authors evaluate the clinical outcomes of the restoration method and investigate whether this technique could be used as an alternative to conventional methods. MATERIALS AND METHODS Two new techniques, the resin block and the clear matrix, were studied by treating 8 teeth. The occlusal surface of stainless steel crowns was used for impression-taking to facilitate accurate reproduction of the anatomic structure, and the aesthetic restoration was obtained simply and consistently. RESULTS At the 24-month follow-up evaluation, these new direct techniques were completely satisfactory. Marginal discoloration was observed in one tooth treated with the clear matrix technique, and a small partial wear was observed in another tooth treated with the resin block. CONCLUSION The new techniques for restoration resulted in functional and aesthetic reproduction of occlusal morphology. Therefore, these techniques could be considered a practical alternative to conventional methods.
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Nguyen LM, Kuroyanagi R, Tsuchizawa T, Ishikawa Y, Yamada K, Wada K. Stress tuning of the fundamental absorption edge of pure germanium waveguides. OPTICS EXPRESS 2015; 23:18487-18492. [PMID: 26191906 DOI: 10.1364/oe.23.018487] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
One-dimensional stress dependence on the fundamental absorption edge of pure germanium (Ge) waveguide has theoretically and experimentally been studied, considering built-in two-dimensional stress-tensile Ge grown on Si. Based on the results, we have designed Ge Franz-Keldysh (FK) electroabsorption (EA) modulators to work at 1550 nm. Application of one-dimensional [110] compressive stress above -350 MPa on a pure Ge [-110] waveguide should allow 1550 nm light transmission, unless otherwise a pure Ge modulator can only operate at 1600 nm or longer due to the built-in two-dimensional tensile stress in Ge. The prediction has experimentally been verified using a SiNx stressor film. This concludes that the presented stress-tuning approach of the pure Ge waveguides should expand the operation wavelength of Ge FK-EA modulators to C band. Since stress tuning can be locally done in the back-end-of-line of complementary metal oxide semiconductor (CMOS) process, the presented stress-tuning method should enable "field-programable" control of the operation wavelengths of the monolithically integrated Ge modulators in Si photonics platform.
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Wada K, Takei N, Sato T, Tsuno H. Sources of organic matter in first flush runoff from urban roadways. WATER SCIENCE AND TECHNOLOGY : A JOURNAL OF THE INTERNATIONAL ASSOCIATION ON WATER POLLUTION RESEARCH 2015; 72:1234-1242. [PMID: 26398040 DOI: 10.2166/wst.2015.307] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
This study aims to explore the influential sources of organic matter in first flush runoff from urban roadways by comparing organic carbon content and particle size distribution in road dust with those from discharge from vehicles during rainfall. Samples on first flush runoff and road dust were collected from urban roadways. In addition, vehicle drainage was assumed to flow from vehicles during rainfall events, so vehicle wash-off water was collected by spraying water onto the top and from the underside of vehicles to simulate accumulation during a vehicle run. In road dust, the organic carbon content in the <0.2 mm fraction was about twice that of the 0.2-2 mm fraction. The particle size distributions of both first flush runoff and vehicle wash-off water were similar, and particles <0.2 mm contributed to over 95% of the total volume. The dissolved organic carbon concentration in the vehicle wash-off water was considerably higher than that in the road dust/water mixture. The total organic carbon content in road dust was positively correlated with annual daily traffic. Therefore, vehicles were thought to strongly influence the nature of road dust.
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Crawford B, Tang A, Li H, Burns L, Wada K, McDonald J. Real World Studies Using Japanese Administrative Databases: Chronic Hepatitis C Treatment Pattern And Resource Use. VALUE IN HEALTH : THE JOURNAL OF THE INTERNATIONAL SOCIETY FOR PHARMACOECONOMICS AND OUTCOMES RESEARCH 2014; 17:A370-A371. [PMID: 27200790 DOI: 10.1016/j.jval.2014.08.843] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
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Crawford B, Kim HR, Wada K. Understanding the Japanese General Public's Rationale for Trades in a Time-Trade-Off Assessment for Systemic Lupus Erythematosus. VALUE IN HEALTH : THE JOURNAL OF THE INTERNATIONAL SOCIETY FOR PHARMACOECONOMICS AND OUTCOMES RESEARCH 2014; 17:A784. [PMID: 27202916 DOI: 10.1016/j.jval.2014.08.397] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
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Shimane T, Matsumoto T, Wada K. P-48 * THE JAPANESE COMMUNITY PHARMACIST AS A "GATEKEEPER" FOR PREVENTING PRESCRIPTION DRUG OVERDOSE. Alcohol Alcohol 2014. [DOI: 10.1093/alcalc/agu054.48] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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Tanibuchi Y, Matsumoto T, Kobayashi O, Wada K. SY13-2-1 * CURRENT STATUS OF SUBSTANCE ABUSE IN JAPAN; FOCUSED ON EVASIVE DRUGS. Alcohol Alcohol 2014. [DOI: 10.1093/alcalc/agu052.55] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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Funada M, Tomiyama K, Wada K. P-47 * HARMFUL EFFECTS OF LAW-EVADING HERBS AS A NEW TREND IN JAPAN: BEHAVIORAL AND CYTOTOXICOLOGICAL PROPERTIES OF SYNTHETIC CANNABINOIDS. Alcohol Alcohol 2014. [DOI: 10.1093/alcalc/agu054.47] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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Fukaya Y, Mochizuki I, Maekawa M, Wada K, Hyodo T, Matsuda I, Kawasuso A. Structure determination of two-dimensional atomic sheet of silicene using TRHEPD. Acta Crystallogr A Found Adv 2014. [DOI: 10.1107/s2053273314083946] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Abstract
This study reports determination of the atomic coordinates of a two-dimensional atomic sheet, silicene, by using total reflection high-energy positron diffraction (TRHEPD) [1]. TRHEPD method, formerly called as RHEPD, is a surface-sensitive tool owing to the total reflection of positrons. Since the sign of the potential energy for positrons in crystals is positive, opposite to that for the electrons, the positron beam at a grazing incidence are totally reflected at a crystal surface. The penetration depth of the positron beam in the total reflection region is estimated to be approximately a few Å, which corresponds to the thickness of 1-2 atomic layers. Thus, the positron beam selectively sees the topmost surface layer and hence the TRHEPD method is very useful for structure determinations of crystal surface and two-dimensional atomic sheet on the substrate. Silicene is a two-dimensional atomic sheet of silicon. Since the silicene has an intriguing property such as a Dirac cone like a graphene, it attracts increasing attention as a candidate for future devices. Recently, the synthesis of silicene on a Ag(111) surface was successfully performed [2]. Although the atomic coordinates of the silicene in this system was theoretically calculated, they were not confirmed experimentally. It is very important to experimentally determine the magnitude of the buckling in silicene and the spacing between the bottom of the silicene and the substrate because the dispersion of the Dirac cone is closely related to these structure parameters. We thus investigated the atomic positions of the silicene on the Ag(111) surface using the TRHEPD [3]. From the rocking curve analysis based on the dynamical diffraction theory of positrons (see figure), the existence of the buckling (0.83 Å) in silicene was verified experimentally. Moreover, the spacing between the silicene and the substrate was determined as 2.17 Å. The structural difference with the graphene will be also discussed.
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Wada K, Maekawa M, Fukaya Y, Mochizuki I, Hyodo T, Shidara T, Kawasuso A. A total reflection high-energy positron diffraction station at the KEK-SPF. Acta Crystallogr A Found Adv 2014. [DOI: 10.1107/s2053273314083867] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Abstract
A high-intensity mono-energetic positron beam generated by using a linear electron accelerator (linac) provides total reflection high-energy positron diffraction (TRHEPD) researches at Slow Positron Facility (SPF), KEK [1,2]. A pulsed 50-Hz electron beam generated with a dedicated linac (operated at 55 MeV, 0.6 kW) is injected on a Ta converter and causes fast positron-electron pair creation through bremsstrahlung. The positrons showering down on 25 μm-thick W foils, are moderated to thermal energy, and a fraction spontaneously comes out of the foils with an energy of 3 eV owing to the negative work function. The positron converter/moderator assembly is held at an electrostatic voltage of 15 kV for TRHEPD experiment. The emitted positrons are consequently accelerated to 15 keV as they enter the grounded beam-line and are guided by the magnetic field of about 0.015 T to the TRHEPD station. For diffraction experiments, positrons transported by the magnetic field have to be first released into a nonmagnetic region. Since the released positron beam has a large diameter, a brightness-enhancement unit is effectively used to achieve a small-diameter and highly-parallel beam with a sufficient flux. The linac-based positron beam gives about 60 times intensified diffraction pattern from a Si(111)-7x7 reconstructed surface compared to a previous result with a Na-22-based positron beam [3]. An improved signal-to-noise ratio in the obtained pattern due to the intensified beam allowed an observation of clear fractional-order spots in the higher Laue-zones, which had not been observed previously. The much intensified beam with the present system allows adjustment of the sample orientation without accumulating the positron signals. With the brightness enhanced beam, several remarkable results have been obtained efficiently by users of this facility. (Everybody is invited to use KEK Slow Positron Facility through approval of his/her research proposal.)
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Hyodo T, Fukaya Y, Mochizuki I, Maekawa M, Wada K, Shidara T, Ichimiya A, Kawasuso A. Surface sensitivity of total reflection high-energy positron diffraction. Acta Crystallogr A Found Adv 2014. [DOI: 10.1107/s2053273314083880] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Abstract
"Reflection high-energy positron diffraction (RHEPD) is the positron counterpart of reflection high-energy electron diffraction (RHEED). RHEPD was proposed in 1992 [1], and first demonstrated in 1998 [2]. Unlike the case of the electron, the potential energy of the positron inside a crystal is positive, and hence positrons incident on a crystal surface with a glancing angle smaller than a certain critical angle are totally reflected. This feature makes the positrons a tool extremely sensitive to the topmost layer of the crystal surface. Recent development of a brightness-enhanced intense positron beam at KEK [K. Wada, et al., J. Phys.: Conf. Ser. 443, 012082 (2013)] has made it possible to obtain clear RHEPD patterns. We rename the technique with a refined beam as ""total reflection high-energy positron diffraction (TRHEPD)"". Here we demonstrate that the TRHEPD pattern from the Si(111)-7x7 DAS surface taken with a glancing angle smaller than the critical angle for the total reflection is essentially determined only by the atoms exposed on the surface (adatoms and the atoms in the first surface layer) [3]. The technical details of the positron beam preparation [M. Maekawa, et al., to be published in Eur. Phys. J. D (2014)], results on the Pt/Ge(001) nano-wire surface[I. Mochizuki, et al., Phys. Rev. B 85, 245438 (2012)], TiO2(110)-1x2 surface, and silicene on Ag(111) surface [Y. Fukaya, et al., Phys. Rev. B 88 205413 (2013)] are also presented in this conference. "
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Mochizuki I, Fukaya Y, Ariga H, Wada K, Hyodo T, Shidara T, Maekawa M, Kawasuso A, Asakura K. TRHEPD rocking curve analyses of Pt/Ge(001) and TiO 2(110) surfaces. Acta Crystallogr A Found Adv 2014. [DOI: 10.1107/s2053273314083879] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Abstract
Recently, we developed new total reflection high-energy positron diffraction (TRHEPD) apparatus [1] on a beam line of the linac-based intense positron beam of the Slow Positron Facility at KEK, Japan. The high intensity allows us to install a brightness-enhancement section, which to observation of clear positron diffraction patterns for crystal surfaces under total reflection condition. In this work, we investigated the atomic configuration of Pt-induced nanowires formed on a Ge(001) surface [2] using the apparatus. By means of the diffraction intensity analysis based on the dynamical diffraction theory, or TRHEPD rocking curve analysis, a previously proposed theoretical model [D. E. P. Vanpoucke et al., Phys. Rev. B 77, 241308(R) (2008)], composed of Ge dimers on the top layer and buried Pt arrays in the second and fourth layers, was confirmed to be the fundamental structure of the nanowire. We also investigated the atomic configuration of a rutile-TiO2(110) surface. It is well known that the structure of this surface transforms its periodicity from (1×1) to (1×2) by elevating the sample temperature above ~1100 K, whereas the detailed structure is yet to be revealed. There is a longstanding controversy between the structure models proposed by scanning tunneling microscopy, low energy electron diffraction, surface X-ray diffraction, first-principles calculation with density functional theory results, etc. To solve the problem, we have measured TRHEPD rocking curves and determined the atomic arrangements of the topmost crystal surface [3].
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Gould A, Udalski A, Shin IG, Porritt I, Skowron J, Han C, Yee JC, Kozłowski S, Choi JY, Poleski R, Wyrzykowski Ł, Ulaczyk K, Pietrukowicz P, Mróz P, Szymański MK, Kubiak M, Soszyński I, Pietrzyński G, Gaudi BS, Christie GW, Drummond J, McCormick J, Natusch T, Ngan H, Tan TG, Albrow M, DePoy DL, Hwang KH, Jung YK, Lee CU, Park H, Pogge RW, Abe F, Bennett DP, Bond IA, Botzler CS, Freeman M, Fukui A, Fukunaga D, Itow Y, Koshimoto N, Larsen P, Ling CH, Masuda K, Matsubara Y, Muraki Y, Namba S, Ohnishi K, Philpott L, Rattenbury NJ, Saito T, Sullivan DJ, Sumi T, Suzuki D, Tristram PJ, Tsurumi N, Wada K, Yamai N, Yock PCM, Yonehara A, Shvartzvald Y, Maoz D, Kaspi S, Friedmann M. Exoplanet detection. A terrestrial planet in a ~1-AU orbit around one member of a ~15-AU binary. Science 2014; 345:46-9. [PMID: 24994642 DOI: 10.1126/science.1251527] [Citation(s) in RCA: 94] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Using gravitational microlensing, we detected a cold terrestrial planet orbiting one member of a binary star system. The planet has low mass (twice Earth's) and lies projected at ~0.8 astronomical units (AU) from its host star, about the distance between Earth and the Sun. However, the planet's temperature is much lower, <60 Kelvin, because the host star is only 0.10 to 0.15 solar masses and therefore more than 400 times less luminous than the Sun. The host itself orbits a slightly more massive companion with projected separation of 10 to 15 AU. This detection is consistent with such systems being very common. Straightforward modification of current microlensing search strategies could increase sensitivity to planets in binary systems. With more detections, such binary-star planetary systems could constrain models of planet formation and evolution.
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Chichibu SF, Sota T, Wada K, DenBaars SP, Nakamura S. Spectroscopic Studies in InGaN Quantum Wells. ACTA ACUST UNITED AC 2014. [DOI: 10.1557/s1092578300002295] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Fundamental electronic modulations in strained wurtzite III-nitride, in particular InxGa1−xN, quantum wells (QWs) were treated to explore the reason why practical InGaN devices emit bright luminescences in spite of the large threading dislocation (TD) density. The emission mechanisms were shown to vary depending on the well thickness L and InN molar fraction x. The electric field across the QW plane, F, which is a sum of the fields due to spontaneous and piezoelectric polarization and the pn junction field, causes the redshift of the ground state resonance energy through the quantum confined Stark effect (QCSE). The absorption spectrum is modulated by QCSE, quantum-confined Franz-Keldysh effect (QCFK), and Franz-Keldysh (FK) effect from the barrires when, for the first approximation, potential drop across the well (FL) exceeds the valence band discontinuity, EV. Under large FL, holes are confined in the triangular potential well formed at one side of the well. This produces apparent Stokes-like shift in addition to the in-plane net Stokes shift on the absorption spectrum. The QCFK and FK further modulate the electronic structure of the wells with L greater than the three dimensional (3D) free exciton (FE) Bohr radius, aB. When FL exceeds EC, both electron (e) and hole (h) confined levels drop into the triangular potential wells at opposite sides of the wells, which reduces the wavefunction overlap. Doping of Si in the barriers partially screens the F resulting in a smaller Stokes-like shift, shorter recombination decay time, and higher emission efficiency. Finally, the use of InGaN was found to overcome the field-induced oscillator strength lowering due to the spontaneous and piezoelectric polarization. Effective in-plane localization of the QW excitons (confined excitons, or quantized excitons) in quantum disk (Q-disk) size potential minima, which are produced by nonrandom alloy potential fluctuation enhanced by the large bowing parameter and F, produces confined e-h pairs whose wavefunctions are still overlapped when L<aB. Their Coulomb interaction is more pronounced for FL<EV.
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Fukaya Y, Maekawa M, Mochizuki I, Wada K, Hyodo T, Kawasuso A. Reflection high-energy positron diffraction study on the first surface layer. ACTA ACUST UNITED AC 2014. [DOI: 10.1088/1742-6596/505/1/012005] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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Hyodo T, Fukaya Y, Maekawa M, Mochizuki I, Wada K, Shidara T, Ichimiya A, Kawasuso A. Total reflection high-energy positron diffraction (TRHEPD). ACTA ACUST UNITED AC 2014. [DOI: 10.1088/1742-6596/505/1/012001] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Kobayashi Y, Kariya T, Chishima J, Fujii K, Wada K, Baba S, Itoo T, Nakaoka T, Kawashima M, Saito S, Aoki N, Hayama S, Osa Y, Osada H, Niizuma A, Suzuki M, Uekane Y, Hayashi K, Kobayashi M, Ohtaishi N, Sakurai Y. Population trends of the Kuril harbour seal Phoca vitulina stejnegeri from 1974 to 2010 in southeastern Hokkaido, Japan. ENDANGER SPECIES RES 2014. [DOI: 10.3354/esr00553] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
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