Climate change, land use change, and China’s food security in the twenty-first century: an integrated perspective   总被引：5，自引：0，他引：5  

Fulu Tao  Masayuki Yokozawa  Jiyuan Liu  Zhao Zhang 《Climatic change》2009,93(3-4):433-445

Food security in China, the world’s most populous country, has long been a concern because of the challenges of population growth, water shortages, and loss of cropland through urbanization, soil degradation, and climate change. Here, we present an integrated analysis of China’s food demand and supply under IPCC Special Report on Emissions Scenarios A1, A2, B1, and B2 in 2020, 2050, and 2080, based on official statistics and future development scenarios. Our analysis accounts for future socioeconomic, technological, and resource developments, as well the impact of climate change. We present a covariant relationship between changes in cereal productivity due to climate change and the cereal harvest area required to satisfy China’s food demand. We also estimated the effects of changing harvested areas on the productivity required to satisfy the food demand; of productivity changes due to climate change on the harvest area required to satisfy food demand; and of productivity and land use changes on the population at risk of undernutrition. China could be able to feed herself without disturbing the global food market in the twenty-first century, but whether the government will choose self-sufficiency or increased food imports may depend on the cost of change, which remains unknown.  相似文献   

The escape of ionizing photons from supernova-dominated primordial galaxies     

Hidenobu Yajima  Masayuki Umemura  Masao Mori  Taishi Nakamoto 《Monthly notices of the Royal Astronomical Society》2009,398(2):715-721

In order to assess the contribution of Lyman break galaxies (LBGs) and Lyman α emitters (LAEs) at redshifts  3 < z < 7  to the ionization of intergalactic medium (IGM), we investigate the escape fractions of ionizing photons from supernova-dominated primordial galaxies by solving the three-dimensional (3D) radiative transfer. The model galaxy is employed from an ultra-high-resolution chemodynamic simulation of a primordial galaxy by Mori & Umemura, which well reproduces the observed properties of LAEs and LBGs. The total mass of model galaxy is  10¹¹ M_⊙  . We solve not only photoionization but also collisional ionization by shocks. In addition, according to the chemical enrichment, we incorporate the effect of dust extinction, taking the size distributions of dust into account. As a result, we find that dust extinction reduces the escape fractions by a factor of 1.5–8.5 in the LAE phase and by a factor of 2.5–11 in the LBG phase, while the collisional ionization by shocks increases the escape fractions by a factor of  ≈2  . The resultant escape fractions are 0.07–0.47 in the LAE phase and 0.06–0.17 in the LBG phase. These results are well concordant with the recent estimations derived from the flux density ratio at 1500 to 900 Å of LAEs and LBGs. Combining the resultant escape fractions with the luminosity functions of LAEs and LBGs, we find that high- z LAEs and LBGs can ionize the IGM at   z = 3–5  . However, ionizing radiation from LAEs as well as LBGs falls short of ionizing the IGM at   z > 6  . That implies that additional ionization sources may be required at   z > 6  .  相似文献   

Raman spectroscopic study of diamond and graphite in ureilites and the origin of diamonds     

Kana NAGASHIMA  Masayuki NARA  Jun‐ichi MATSUDA 《Meteoritics & planetary science》2012,47(11):1728-1737

Abstract– We performed micro‐Raman spectroscopic analyses of the carbon vein in five ureilites: Allan Hills (ALH) A77257, Northwest Africa (NWA) 3140, Shi?r 007, Yamato 790981 (Y‐790981), and Yamato 791538 (Y‐791538). The graphite peaks showed that the graphite structure in ureilite is well developed, especially compared with the carbonaceous material in carbonaceous chondrite. The domain sizes of the graphite were 45–110 Å. We observed shifts in the diamond peak positions to higher wave numbers with a large full width at half maximum (FWHM), especially for NWA 3140. Although the FWHM of a diamond peak is not a crucial diagnostic test for a chemical vapor deposition (CVD) origin of diamond, the shift of the diamond peaks to higher wave numbers could be a strong indicator that supports the CVD origin as these shifts have only been observed in CVD diamonds. We discuss the origin of diamond from various aspects, and confirm that the CVD model is the most plausible. We conclude that all carbon material (graphite, amorphous carbon, diamond, etc.) condensed on the early condensates in the primitive solar nebula.  相似文献   

Preface     

Hiroyuki Tsubota  Masao Fukasawa  Koh Harada  Akira Nishimura  Masayuki Mac Takahashi  Shigeaki Aoki  Joji Ishizaka  Yutaka W. Watanabe 《Journal of Oceanography》1999,55(6):643-643

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Finite‐element analysis of laminated rubber bearing of building frame under seismic excitation          下载免费PDF全文

Makoto Ohsaki  Tomoshi Miyamura  Masayuki Kohiyama  Takuzo Yamashita  Masashi Yamamoto  Naohiro Nakamura 《地震工程与结构动力学》2015,44(11):1881-1898

Finite element analysis is carried out for a building frame supported by laminated rubber bearings to simultaneously investigate global displacement and local stress responses under seismic excitation. The frame members and the rubber bearings are discretized into hexahedral solid elements with more than 3 million degrees of freedom. The material property of rubber is represented by the Ogden model, and the frame is assumed to remain in elastic range. It is shown that the time histories of non‐uniform stress distribution and rocking behavior of the rubber bearings under a frame subjected to seismic excitation can be successfully evaluated, and detailed responses of base and frame can be evaluated through large‐scale finite element analysis. Copyright © 2015 John Wiley & Sons, Ltd.  相似文献   

Detection and temporal variation of Co in the digestive glands of the common octopus, Octopus vulgaris, in the East China Sea     

Takami Morita  Shigeyoshi Otosaka  Kou Nishiuchi  Haruya Yamada  Masayuki Minakawa 《Marine pollution bulletin》2010,60(8):1193-1199

⁶⁰Co were detected in common octopus specimens collected in the East China Sea in 1996-2005. The source of ⁶⁰Co has remained unclear yet. Stable isotope analyses showed that there was no difference in stable Co concentrations between octopus samples with ⁶⁰Co and without ⁶⁰Co. This result showed that the stable Co in the digestive gland of octopus potentially did not include a trace amount of ⁶⁰Co and the source of ⁶⁰Co existed independently. Furthermore, investigations of octopus in other area and other species indicated that the origin of the source of ⁶⁰Co occurred locally in the restricted area in the East China Sea and not in the coastal area of Japan. Concentrations of ⁶⁰Co have annually decreased with shorter half-life than the physical half-life. This decrease tendency suggests that the sources of ⁶⁰Co were identical and were temporary dumped into the East China Sea as a solid waste.  相似文献   

Seismological asperities from the point of view of dynamic rupture modeling: the 2007 Mw6.6 Chuetsu-Oki,Japan, earthquake     

Hideo Aochi  Masayuki Yoshimi 《Journal of Seismology》2016,20(4):1089-1105

We study the ground motion simulations based on three finite-source models for the 2007 Mw6.6 Niigata Chuetsu-oki, Japan, earthquake in order to discuss the performance of the input ground motion estimations for the near-field seismic hazard analysis. The three models include a kinematic source inverted from the regional accelerations, a dynamic source on a planar fault with three asperities inferred from the very-near-field ground motion particle motions, and another dynamic source model with conjugate fault segments. The ground motions are calculated for an available 3D geological model using a finite-difference method. For the comparison, we apply a goodness-of-fit score to the ground motion parameters at different stations, including the nearest one that is almost directly above the ruptured fault segments. The dynamic rupture models show good performance. We find that seismologically inferred earthquake asperities on a single fault plane can be expressed with two conjugate segments. The rupture transfer from one segment to another can generate a significant radiation; this could be interpreted as an asperity projected onto a single fault plane. This example illustrates the importance of the fault geometry that has to be taken into account when estimating the very-near-field ground motion.  相似文献   

Integrated magnetobiochronology of the Pliocene–Pleistocene Miyazaki succession,southern Kyushu,southwest Japan: Implications for an Early Pleistocene hiatus and defining the base of the Gelasian (P/P boundary type section) in Japan     

Motoyoshi Oda  Shun Chiyonobu  Masayuki Torii  Takashi Otomo  Jumpei Morimoto  Yuri Satou  Hiroshi Ishikawa  Matsuaki Ashikawa  Osamu Tominaga 《Journal of Asian Earth Sciences》2011,40(1):84-97

An integrated magnetobiochronology of the Miyazaki Pliocene–Pleistocene succession in the Miyazaki area, southwest Japan, was established using planktic foraminiferal and calcareous nannofossil biostratigraphy together with paleomagnetic data. The upper Miyazaki succession in the northern Miyazaki region can be divided into the Takanabe, Hisamine (redefined), and Higoyashiki (new) Formations, in ascending order. A depositional hiatus between the Hisamine Formation and the Takanabe and/or older formations was also identified based on integrated magnetobiostratigraphy from five sections including the Nagatani River (NGT) section through the uppermost Miyazaki succession. The hiatus, herein called the Hisamine unconformity, is equivalent to the Kurotaki unconformity between the Miura and Kazusa groups of the Boso Peninsula in central Japan. The depositional hiatus recognised in the lower Pleistocene of Pacific coastal areas in southwestern and central Japan may have resulted from tectonic activity associated with a change in the subduction direction of the Philippine Sea plate, which commenced prior to ca. 2.2 Ma. The youngest unit just below the hiatus is the upper part of the Takanabe Formation in the NGT section. The NGT section represents the continuous Late Pliocene to earliest Pleistocene sequence including the Gauss/Matuyama boundary and is here proposed as the type section for the Pliocene/Pleistocene boundary in Japan, which the IUGS ratified as the base of the Gelasian in 2009.  相似文献   

Formation process of pyrite polyframboid based on the heavy-metal analysis by micro-PIXE     

Hisanari Sugawara  Masayuki Sakakibara  David Belton  Tetsuya Suzuki 《Environmental Earth Sciences》2013,69(3):811-819

Pyrite framboid in sedimentary rocks could be concerned with arsenic contamination in groundwater of acidic environment and has been studied for the formation process of its unique morphology. However, not much has been discussed about the formation process based on the heavy-metal distribution in pyrite framboids and their aggregates. To reveal the formation process of pyrite framboids and their aggregates, mudstone from the Late Cretaceous Hakobuchi Group, central Hokkaido, Japan, are investigated for mode, petrographical, mineralogical, and micro-PIXE (particle-induced X-ray emission) analysis in this study. Spherical and sub-spherical pyrite framboids observed in polyframboids can be divided into two types based on the diameter of framboids (D) and the average diameter of microcrystals (d) within framboids: type 1, ranging from 2 to 9 μm and from 0.4 to 0.9 μm, respectively, and type 2, ranging from 8 to 50 μm and from 0.5 to 1.8 μm, respectively. Based on the quantitative traverse analyses and 2-D elemental mapping results by micro-PIXE, heterogeneities in the concentrations of heavy metals within the analyzed aggregations of pyrite are exhibited. On the basis of the As and Pb zoning patterns, the time range and chronological stages of pyrite-aggregation growth are revealed.  相似文献   

Prediction of ground motion in the Osaka sedimentary basin associated with the hypothetical Nankai earthquake     

Haruko Sekiguchi  Masayuki Yoshimi  Haruo Horikawa  Kunikazu Yoshida  Sunao Kunimatsu  Kenji Satake 《Journal of Seismology》2008,12(2):185-195

We studied the long-period ground motions in the Osaka sedimentary basin, Japan, which contains a 1- to 3-km thickness of sediments and is the site of many buildings or construction structures with long-natural period. We simulated the broadband ground motions likely to be produced by the hypothetical Nankai earthquake: the earthquake expected to give rise to the most severe long-period ground motion within the basin. For the simulation, we constructed multiscale heterogeneous source models based on the Central Disaster Management Council of Japan (CDMC) source model and adopted a hybrid computation method in which long-period motion and short-period motion are computed using a 3-D finite difference method and the stochastic Green’s function method, respectively. In computing long-period motions, we used a 3-D structure model of the crust and the Osaka sedimentary basin. The ground motions are estimated to have peak velocities of 50–90 cm/s, prolonged durations exceeding 300 s, and long predominant periods of 5–10 s in the area with great thickness of sediments. The predominant periods are in agreement with an approximate evaluation by 4 H/V _s where H and V _s are the thickness of the sediment and the average S wave velocity, respectively.  相似文献