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Highly-efficient VCSEL breaking the limit

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Light(Science & Applications) 2024年第6期13卷 1021-1021页

作者： Dieter Bimberg Fumio koyama Kenichi Iga TU Berlin Hardenbergstr.3610623BerlinGermany Bimberg Chinese-German Center for Green Photonics Changchun Institute of OpticsFine Mechanics and PhysicsChinese Academy of SciencesNo.3888 Dong Nan Hu RoadChangchun130033China Tokyo Institute of Technology Nagatsuta 4259Midori-kuYokohama226-8501Japan

VCSELs have become indispensable in the realms of datacenter networks and three-dimensional sensing thanks to their high-energy efficiencies,low-cost and the scalability of their two-dimensional *** boast high energy-efficiency,exceeding 50%at low bias currents,superiority over edge-emitting lasers,particularly for optical interconnects within datacenter ***,there has been no breakthroughs in the efficiency of VCSELs for over a decade.

关键词： limit breakthrough Highly

Estimating effective reproduction number revisited

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Infectious Disease Modelling 2023年第4期8卷 1063-1078页

作者： shinsuke koyama Department of Statistical Modeling The Institute of Statistical Mathematics10-3 Midori-choTachikawa190-8562TokyoJapan Department of Statistical Science Graduate University for Advanced Studies(SOKENDAI)10-3 Midori-choTachikawa190-8562TokyoJapan

Accurately estimating the effective reproduction number is crucial for characterizing the transmissibility of infectious diseases to optimize interventions and responses during epidemic *** this study,we improve the estimation of the effective reproduction number through two main ***,we derive a discrete model to represent a time series of case counts and propose an estimation method based on this *** also conduct numerical experiments to demonstrate the effectiveness of the proposed discretization *** doing so,we enhance the accuracy of approximating the underlying epidemic process compared to previous methods,even when the counting period is similar to the mean generation time of an infectious ***,we employ a negative binomial distribution to model the variability of count data to accommodate ***,given that observed incidence counts follow a negative binomial distribution,the posterior distribution of secondary infections is obtained as a Dirichlet multinomial *** this formulation,we establish posterior uncertainty bounds for the effective reproduction ***,we demonstrate the effectiveness of the proposed method using incidence data from the COVID-19 pandemic.

关键词： Effective reproduction number Epidemic model Overdispersion COVID-19

Effect of bending and tension deformation on the texture evolution and stretch formability of Mg-Zn-RE-Zr alloy

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International Journal of Minerals,Metallurgy and Materials 2022年第7期29卷 1334-1342页

作者： Yuya Ishiguro Xinsheng Huang Yuhki Tsukada Toshiyuki koyama yasumasa Chino Department of Materials Design Innovation Engineering Nagoya UniversityFuro-choChikusa-kuNagoya464-8603Japan Multi-Material Research Institute National Institute of Advanced Industrial Science and Technology2266-98AnagahoraSimo-shidami Moriyama-kuNagoya463-8560Japan

Bending and tension deformations were performed on Mg-1.3 wt%Zn-0.2 wt%RE-0.3 wt%Zr(ZEK100)alloy sheets that initially had a transverse direction(TD)-split *** effects of bending and tension deformations on the texture formation and room-temperature formability of specimens were *** specimen subjected to 3-pass bending and tension deformations exhibited an excellent Erichsen value of 9.6 ***,the Erichsen value deterioration was observed in the specimen subjected to 7-pass *** rolling direction-split texture developed on the surface with an increasing pass number of ***,the clear TD-split texture remained at the central *** a result,a quadrupole texture was macroscopically developed with an increasing pass number of *** reduction in anisotropy by the formation of the quadrupole texture is suggested to be the main reason for the improvement in stretch *** contrast,the generation of coarse grains near the surface is suggested to be the direct cause for the deterioration of the stretch formability of the specimen subjected to 7-pass deformations.

关键词： magnesium alloy texture stretch formability bending and tension deformation mechanical properties

Cowpea NAC1/NAC2 transcription factors improve growth and tolerance to drought and heat in transgenic cowpea through combined activation of photosynthetic and antioxidant mechanisms

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Journal of Integrative Plant Biology 2023年第1期65卷 25-44页

作者： Richa Srivastava Yuriko Kobayashi Hiroyuki koyama Lingaraj Sahoo Department of Biosciences and Bioengineering Indian Institute of Technology Guwahati Guwahati Assam 781039 India Faculty of Applied Biological Sciences Gifu University 1-1 YanagidoGifu 501-1193Japan

NAC(NAM/ATAF1/2/CUC2)transcription factors are central switches of growth and stress responses in ***,unpredictable interspecies conservation of function and regulatory targets makes the well-studied NAC orthologs inapt for pulse *** knowledge of suitable NAC candidates in hardy pulses like cowpea(Vigna unguiculata(L.)Walp.)is still in infancy,hence warrants immediate biotechnological ***,we showed that overexpression of two native NAC genes(VuNAC1and VuNAC2)promoted germinative,vegetative,and reproductive growth and conferred multiple abiotic stress tolerance in a commercial cowpea *** transgenic lines displayed increased leaf area,thicker stem,nodule-rich denser root system,early flowering,higher pod production(~3.2-fold and~2.1-fold),and greater seed weight(10.3%and 6.0%).In contrast,transient suppression of VuNAC1/2 caused severe growth retardation and flower *** overexpressor lines showed remarkable tolerance to major yielddeclining terminal stresses,such as drought,salinity,heat,and cold,and recovered growth and seed production by boosting photosynthetic activity,water use efficiency,membrane integrity,Na^(+)/K^(+)homeostasis,and antioxidant *** comparative transcriptome study indicated consolidated activation of genes involved in chloroplast development,photosynthetic complexes,cell division and expansion,cell wall biogenesis,nutrient uptake and metabolism,stress response,abscisic acid,and auxin *** their orthologs,VuNAC1/2 direct synergistic transcriptional tuning of stress and developmental signaling to avoid unwanted *** overexpression governs the favorable interplay of photosynthesis and reactive oxygen species regulation to improve stress recovery,nutritional sufficiency,biomass,and *** unconventional balance of strong stress tolerance and agronomic quality is useful for translational crop research and molecular breeding of pulses.

关键词： cowpea enhanced photosynthetic activity improved growth improved yield legume genetic engineering multiple stress tolerance NAC transcription factor VuNAC

An Experimental Study of Carbon Dioxide Condensation in Mini Channels

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Journal of Thermal Science 2004年第4期13卷 358-365页

作者： Shigeru koyama Institute of Advanced Material Study Kyushu University Kasuga-koen 6-1 Kasuga-shi Fukuoka 816-8580Japan

In this study, the local characteristics of pressure drop and heat transfer were investigated experimentally for carbon dioxide condensation in a multi-port extruded aluminum test section, which had 10 circular channels each with 1.31 mm inner diameter. The CO2 was cooled with cooling water flow inside the copper blocks that were attached at both sides of the test section. The temperatures at the outer surface of the test section were measured with 24 K-type thermocouples embedded in the upper and lower surfaces along the length. Local heat fluxes were measured with 12 heat flux sensors to estimate the local enthalpies, temperatures and heat transfer coefficients. Bulk mean temperatures of CO2 at the inlet and outlet of the test section were measured with 2 K-type thermocouples. The measurements were performed for the pressure ranged from 6.48 to 7.3 MPa, inlet temperature of CO2 from 21.63 to 31.33℃, heat flux from 1.10 to 8.12 kW/m2, mass velocity from 123.2 to 315.2 kg/m2s, and vapor quality from 0 to 1. The results indicate that pressure drop is very small along the test section, heat transfer coefficient in the two-phase region is higher than that in the single-phase, and mass velocity has important effect on condensation heat transfer characteristics. In addition, experimental data were compared with previous correlations and large discrepancies were observed.

关键词： carbon dioxide condensation heat transfer pressure drop mini channels.

New functions of VCSEL-based optical devices Invited Paper

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Chinese Optics Letters 2008年第10期6卷 755-762页

作者： Fumio koyama Microsystem Research Center Precision and Intelligence LaboratoryTokyo Institute of Technology 4259-R2-22 NagatsutaMidori-kuYokohama 226-8503Japan

We have seen a lot of unique features off vertical cavity surface emitting lasers （VCSELs）, such as low power consumption, wafer-level testing, small packaging capability, and so on. The market of VCSELs has been growing up rapidly in recent years and they are now the key devices in local area networks using multi-mode optical fibers. In addition, new functions on VCSELs have been demonstrated. In this paper, the recent advances of VCSEL photonics will be reviewed which include the wavelength engineering and the athermal operation based on microelectro mechanical system （MEMS） technologies. Also, this paper explores the potential and challenges for new functions of VCSELs, including high-speed control of optical phase, slow light devices, plasmonic VCSELs, and so on.

关键词： VCSEL New functions of VCSEL-based optical devices Invited Paper

A New Consistency Test forΛCDM Cosmology Using Galaxy Surveys

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Research in Astronomy and Astrophysics 2022年第6期22卷 183-189页

作者： Jinglan Zheng Gong-Bo Zhao Yuting Wang Xiaoyong Mu Ruiyang Zhao Weibing Zhang Shuo Yuan David Bacon Kazuya koyama National Astronomy Observatories Chinese Academy of SciencesBeijing 100101China School of Astronomy and Space Science University of Chinese Academy of SciencesBeijing 100049China Institute of Cosmology and Gravitation University of PortsmouthDennis Sciama BuildingPortsmouth PO13FXUK

We propose a new consistency test for theΛCDM cosmology using baryonic acoustic oscillations(BAO)and redshift space distortion(RSD)measurements from galaxy redshift ***,we determine the peak position of fσ8(z)in redshift z offered by an RSD measurement,and compare it to the one predicted by the BAO observables assuming a flatΛCDM *** demonstrate this new test using the simulated data for the DESI galaxy survey,and argue that this test complements those using the background observables alone,and is less subject to systematics in the RSD analysis,compared to traditional methods using values of fσ8(z)directly.

关键词： Cosmology-(cosmology:)dark energy-galaxies distances and redshifts

Endoscopic diagnosis of Barrett's esophagus

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World Journal of Gastroenterology 2012年第26期18卷 3477-3478页

作者： Tomoyuki Akiyama Yusuke Sekino Hiroshi Iida Shigeru koyama Eiji Gotoh shin Maeda Atsushi Nakajima Masahiko Inamori Department of Gastroenterology Tokyo Metropolitan Hiroo HospitalTokyo 150-0013Japan Gastroenterology Division Yokohama City University HospitalYokohama 2360004Japan Department of Medical Education Yokohama City University School of MedicineYokohama 2360004Japan Office of Postgraduate Medical Education Yokohama City University HospitalYokohama 2360004Japan

The Prague C and M Criteria have been developed for the objective endoscopic diagnosis of Barrett's esophagus(BE).BE arises between the squamocolumnar junction and the gastroesophageal junction at the proximal margin of the gastric *** this study,we reported that 43.0% of the subjects examined were diagnosed with BE based on the Prague C and M *** criticism by John Dent proposed that our data should be considered invalid because the prevalence of BE reported in our study was extraordinarily high and discordant with previous *** predicted that the position of the gastroesophageal junction in our study was judged to be lower than the actual position due to the effacement of the proximal ends of the gastric folds because of the routine use of a high degree of air distension during typical Japanese endoscopic *** endoscopic evaluation of the superior gastric folds is certainly influenced by the degree of air distension of the ***,in our study,the proximal limit of the gastric mucosal folds was prospectively imaged while the oesophagus was minimally ***,under a high level of air distension,the distal ends of the palisade-shaped longitudinal vessels were imaged because they are more easily observed when *** the majority of patients,the distal ends of the palisade-shaped longitudinal vessels correspond to the proximal limit of the gastric mucosal *** endoscopic evaluation was appropriately performed according to the Prague C and M *** suspect that the high prevalence of BE in our study may be due to the inclusion of ultrashort-segment BE,which defines BE with an affected mucosal length under 5 mm,in our positive results.

关键词：内镜食管诊断胃粘膜布拉格交界处患病率标准

Pro-and anti-epileptic roles of microglia

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Neural Regeneration Research 2021年第7期16卷 1369-1371页

作者： shinichi Kinoshita Ryuta koyama Laboratory of Chemical Pharmacology Graduate School of Pharmaceutical SciencesThe University of TokyoTokyoJapan

Microglia are brain-resident immune cells that contribute to the maintenance of brain *** the epileptic brain, microglia show various activation phenotypes depending on the stage of ***, it remains unclear whether microglial activation acts in a pro-epileptic or anti-epileptic *** mesial temporal lobe epilepsy, one of the most common form of epilepsies, microglia exhibit at least two distinct morphologies, amoeboid shape and ramified *** microglia are often found in sclerotic area, whereas ramified microglia are mainly found in non-sclerotic area;however, it remains unclear whether these structurally distinct microglia share separate roles in the epileptic ***, we review the roles of the two distinct microglial phenotypes, focusing on their pro-and anti-epileptic roles in terms of inflammatory response, regulation of neurogenesis and microglia-neuron interaction.

关键词： epilepsy epileptogenesis inflammatory cytokines microglia neurogenesis neuron-microglia interaction seizure