Vibrant Centers as Locations for High-Growth Firms: An Analysis of Thirty U.S. Metropolitan Areas     

Emil Malizia  Yasuyuki Motoyama 《The Professional geographer》2019,71(1):15-28

What kinds of places have high entrepreneurial activities? There has been an emerging body of studies about so-called entrepreneurship ecosystems, but virtually all of the past studies have examined this question from a perspective of which metropolitan areas have higher entrepreneurial activities. In this article, we examine the intrametropolitan scale at the Census tract level. By analyzing thirty metropolitan areas to extend external validity, we demonstrate the concentration of high-growth firms in specific employment nodes in both urban and suburban parts of each metropolitan area. Significant correlations exist between place-based vibrancy indicators and high-growth firm concentrations.  相似文献   

Trends,drivers and impacts of changes in swidden cultivation in tropical forest-agriculture frontiers: A global assessment     

Nathalie van Vliet  Ole Mertz  Andreas Heinimann  Tobias Langanke  Unai Pascual  Birgit Schmook  Cristina Adams  Dietrich Schmidt-Vogt  Peter Messerli  Stephen Leisz  Jean-Christophe Castella  Lars Jørgensen  Torben Birch-Thomsen  Cornelia Hett  Thilde Bech-Bruun  Amy Ickowitz  Kim Chi Vu  Kono Yasuyuki  Jefferson Fox  Christine Padoch  Alan D. Ziegler 《Global Environmental Change》2012,22(2):418-429

This meta-analysis of land-cover transformations of the past 10–15 years in tropical forest-agriculture frontiers world-wide shows that swidden agriculture decreases in landscapes with access to local, national and international markets that encourage cattle production and cash cropping, including biofuels. Conservation policies and practices also accelerate changes in swidden by restricting forest clearing and encouraging commercial agriculture. However, swidden remains important in many frontier areas where farmers have unequal or insecure access to investment and market opportunities, or where multi-functionality of land uses has been preserved as a strategy to adapt to current ecological, economic and political circumstances. In some areas swidden remains important simply because intensification is not a viable choice, for example when population densities and/or food market demands are low. The transformation of swidden landscapes into more intensive land uses has generally increased household incomes, but has also led to negative effects on the social and human capital of local communities to varying degrees. From an environmental perspective, the transition from swidden to other land uses often contributes to permanent deforestation, loss of biodiversity, increased weed pressure, declines in soil fertility, and accelerated soil erosion. Our prognosis is that, despite the global trend towards land use intensification, in many areas swidden will remain part of rural landscapes as the safety component of diversified systems, particularly in response to risks and uncertainties associated with more intensive land use systems.  相似文献   

Sound velocity and density of liquid Ni68S32 under pressure using ultrasonic and X-ray absorption with tomography methods     

Hidenori Terasaki  Keisuke Nishida  Satoru Urakawa  Yusaku Takubo  Soma Kuwabara  Yuta Shimoyama  Kentaro Uesugi  Yoshio Kono  Akihisa Takeuchi  Yoshio Suzuki  Yuji Higo  Tadashi Kondo 《Comptes Rendus Geoscience》2019,351(2-3):163-170

A new experimental setup for simultaneous P-wave velocity (V_P) and density (ρ) measurements for liquid alloys is developed using ultrasonic and X-ray absorption methods combined with X-ray tomography at high pressures and high temperatures. The new setup allows us to directly determine adiabatic bulk moduli (K_S) and to discuss the correlation between the V_P and ρ of the liquid sample. We measured V_P and ρ of liquid Ni₆₈S₃₂ up to 5.6 GPa and 1045 K using this technique. The effect of pressure on the V_P and ρ values of liquid Ni₆₈S₃₂ is similar to that of liquid Fe₅₇S₄₃. (Both compositions correspond to near-eutectic ones.) The obtained K_S values are well fitted to the finite strain equation with a $K_{{\text{S}}_0}$ value (K_S at ambient pressure) of 31.1 GPa and a dK_S/dP value of 8.44. The measured V_P was found to increase linearly with increasing ρ, as approximated by the relationship: V_P [m/s] = 1.29 ρ [kg/m³] – 5726, suggesting that liquid Ni–S follows an empirical linear relationship, Birch's law. The dV_P/dρ slope is similar between Ni₆₈S₃₂ and Fe₅₇S₄₃ liquids, while the V_P–ρ plot of liquid Ni–S is markedly different from that of liquid Fe–S, which indicates that the effect of Ni on Birch's law is important for understanding the V_P–ρ relation of planetary and Moon's molten cores.  相似文献   

Organic carbon and microbial biomass in a raised beach deposit under terrestrial vegetation in the High Arctic, Ny-Ålesund, Svalbard     

Takayuki Nakatsubo  Shinpei Yoshitake  Masaki Uchida  Masao Uchida  Yasuyuki Shibata  & Hiroshi Koizumi 《Polar research》2008,27(1):23-27

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Application of an ecosystem model for the environmental assessment of the reclamation and mitigation plans for seagrass beds in Atsumi Bay   总被引：1，自引：0，他引：1  

Akio Sohma  Yasuyuki Sekiguchi  Kisaburo Nakata 《Estuarine, Coastal and Shelf Science》2009

An ecosystem model was used to evaluate the effects of reclaiming seagrass beds and creating artificial shallows with seagrass beds to mitigate the effects of the reclamation. The applied model can simulate the pelagic and benthic ecosystems including seagrass beds and tidal flats. The objectives of this study were (a) to investigate the likelihood of cultivating and maintaining seagrass beds in artificial shallows (Part 1), and (b) to understand the effects of the reclamation of seagrass beds and the creation of artificial shallows on the water quality in the estuary (Part 2). In Part 1, first, the nutrient turnover rates due to both biochemical and physical processes in the natural seagrass beds where reclamation is proposed were analyzed. Biological processes rather than physical processes were the most significant driving forces of nutrient cycles in seagrass beds. Second, the effects of filter feeding benthic fauna (suspension feeders) in the seagrass beds were analyzed. The scenario with suspension feeders resulted in higher transparency of the water column (8.7% decrease in the light attenuation coefficient) and an increase in nutrient supply (24.9% increase in NH₄-N in the water column) contributing to the high specific growth rate of seagrass. Third, the specific growth rate of seagrass on the proposed artificial shallows was measured. The value on the artificial shallows set at a depth of datum line minus 0.8 m (D.L. − 0.8 m) was approximately the same as that of the natural seagrass beds. In Part 2, first, water quality in the estuary was compared among the scenarios with/without natural seagrass beds and artificial shallows. Then, the defined values of the water purification capability of (a) artificial shallows with/without seagrass beds, and (b) natural seagrass beds per unit area were evaluated. The reclamation of the natural seagrass beds resulted in a decrease of the removal of phytoplankton and detritus from the pelagic system (i.e. resulted in a loss in the purification rate). In contrast, the creation of artificial shallows resulted in an increase of the removal of phytoplankton and detritus from the pelagic system (i.e. resulted in a gain in the purification rate). Based on an annual average, approximately twice as much phytoplankton was removed from the artificial shallows at the depth D.L. − 0.8 m, than at the depth, D.L. − 1.5 m, and the artificial shallows with seagrass beds removed pelagic DIN and DIP at a rate 120% higher than that without seagrass beds.  相似文献   

Large-amplitude internal waves observed in the Kruzenshtern Strait of the Kuril Island Chain and possible water transport and mixing     

Tomohiro Nakamura  Yasuhiro Kawasaki  Tokihiro Kono  Toshiyuki Awaji 《Continental Shelf Research》2010

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Rare-earth and trace elements in the Quaternary volcanic rocks of Hokkaido,Japan     

Yasuyuki Masuda  Susumu Nishimura  Takashi Ikeda  Yoshio Katsui 《Chemical Geology》1975,15(4):251-271

Seven rare-earth elements (La, Ce, Sm, Eu, Tb, Yb, Lu) and Co, Cr, Sc, Ba, Hf and Th have been determined by non-destructive neutron activation analysis on the Quaternary volcanic rocks in Hokkaido, Japan. The trace-element abundances are discussed in terms of the petrological problems, particularly the origin of calc-alkali magma. On the basis of the La/Sm ratio and the contents of K, Ba, Th and La, lateral variations in the contents of trace elements exist across the Kurile and the northern Honshū arcs. The calc-alkali rocks can be classified into three types which correspond to Kuno's three basalt-magma types. There is no essential difference in the rare-earth patterns between the basaltic rocks and the associated calc-alkali rocks in each petrographic province. This suggests that the calcalkali rocks may be derived from the basaltic magmas by fractional crystallization under certain conditions.  相似文献   

Basalt platforms in Inner Mongolia and Hebei Province, northeastern China: New K–Ar ages, geochemistries, and revision of palaeomagnetic results     

Zhong Zheng  Hidefumi Tanaka  Yoshiyuki Tatsumi  Masaru Kono 《Geophysical Journal International》2002,151(2):654-662

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Erratum to “A new coastal marine ecosystem model study coupled with hydrodynamics and tidal flat ecosystem effect” [Marine Pollution Bulletin 43 (2001) 187-208]     

Akio Sohma  Yasuyuki SekiguchiHiroshi Yamada  Tatsuaki SatoKisaburo Nakata 《Marine pollution bulletin》2002,44(5):432-439

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A New Coastal Marine Ecosystem Model Study Coupled with Hydrodynamics and Tidal Flat Ecosystem Effect   总被引：3，自引：0，他引：3  

Akio Sohma  Yasuyuki Sekiguchi  Hiroshi Yamada  Tatsuaki Sato  Kisaburo Nakata 《Marine pollution bulletin》2001,43(7-12):187-208

A new coastal marine ecosystem model was developed, which was composed of pelagic and benthic ecosystems, and was applied to Mikawa Bay, Japan. This model deals with variations of biochemical and physical interactions among dissolved oxygen and C–N–P species (composition formed out of carbon, nitrogen and phosphorus elements) so that it resolves the flux dynamics of carbon, nitrogen, phosphorus and oxygen elements. The physical and biochemical mechanism figured in this model is constructed for the purpose of simulating the estuarine lower trophic ecosystem, in areas where the sea was too deep for light to reach the sea-bottom. As a result of coupling the benthic with pelagic system, the effect of process of sedimentation and nutrient diffusion back to the pelagic system could be indicated. In addition, by implementing the tidal flat ecosystem model's calculation result, the integrated model can include the effect of water purification in tidal flats where the light can reach the sea-bottom, and where sea-weed, sea grass and benthic algae exist. In this study, the model indicates that oxygen-depleted water exists at the sea-bottom especially in summer mainly caused by an increase of oxygen consumption in the benthic system and a decrease of the vertical mixing water process. Furthermore, by comparing the case – with the tidal flat ecosystem model and the case without it, the effect of water purification of tidal flat estuaries was indicated. From the viewpoint of a short time scale, the tidal flat has the potential to restrict red tide (rapid increase of phytoplankton), and from the viewpoint of a long time scale, it restricts the sedimentation of detritus. Restricting the sedimentation prevents oxygen-depleted water occurring in the coastal marine system of Mikawa Bay.  相似文献