scholarly journals Bioturbation as a potential mechanism influencing spatial heterogeneity of North Carolina seagrass beds

1998 ◽  
Vol 169 ◽  
pp. 123-132 ◽  
Author(s):  
EC Townsend ◽  
MS Fonseca
Keyword(s):  
North Carolina ◽  
Spatial Heterogeneity ◽  
Seagrass Beds ◽  
Potential Mechanism

Disparate effects of biphasic and monophasic shocks on postshock refractory period dispersion

1998 ◽  
Vol 274 (6) ◽  
pp. H1943-H1949 ◽  
Author(s):  
J. Jason Sims ◽  
Allison Winecoff Miller ◽  
Michael R. Ujhelyi
Keyword(s):  
Spatial Heterogeneity ◽  
Pulse Duration ◽  
Refractory Period ◽  
Potential Mechanism ◽  
Data Support ◽  
Important Regulator ◽  
The Difference

The magnitude by which a defibrillation shock extends the refractory period immediately postshock (refractory period extension, RPE) does not explain why biphasic shocks defibrillate with greater efficacy than monophasic shocks. It may be that spatial heterogeneity of RPE is a more important regulator of defibrillation efficacy. We measured RPE in 15 pentobarbital-anesthetized swine using 400-V biphasic and monophasic shocks of equal pulse duration at three discrete myocardial sites. Spatial heterogeneity of RPE was calculated as the difference between the maximum and minimum values of the three recording sites. Monophasic shocks produced greater magnitude of RPE than biphasic shocks at all sites tested (82 ± 6 to 99 ± 13 and 64 ± 6 to 68 ± 5 ms, respectively; P < 0.05). However, RPE dispersion was significantly less with biphasic shocks versus monophasic shocks (29 ± 4 and 48 ± 7 ms, respectively; P < 0.05). This suggests that one potential mechanism by which biphasic shocks defibrillate with greater efficacy is limiting postshock spatial heterogeneity of refractoriness. Thus these data support our hypothesis that RPE heterogeneity is a more likely predictor of defibrillation efficacy than magnitude of RPE.

scholarly journals Factors on Spatial Heterogeneity of the Grain Production Capacity in the Major Grain Sales Area in Southeast China: Evidence from 530 Counties in Guangdong Province

Land ◽  
2021 ◽  
Vol 10 (2) ◽  
pp. 206
Author(s):  
Wei Fang ◽  
Heliang Huang ◽  
Boxi Yang ◽  
Qiang Hu
Keyword(s):  
Spatial Heterogeneity ◽  
Influencing Factors ◽  
Production Capacity ◽  
Guangdong Province ◽  
Policy Implications ◽  
Grain Production ◽  
Potential Mechanism ◽  
The West ◽  
Attenuation Effect ◽  
Grain Security

Grain security is an essential issue for countries across the world. China has witnessed over the last decades not only a rapid growth in the volume of the grain production, but also a divergence in its geographical distributions. Existing studies on the influencing factors of grain production have overlooked thus spatial heterogeneity. This paper investigates the factors that cause the geographical heterogeneity in grain output levels in Guangdong province of China, in terms of land, labor and capital. To address the spatial attenuation effect of the influencing factors, we use the Geographically Weighted Regression (GWR) on samples of different spatial ranges, which include a total of 530 southern counties from 2015 to 2017. The results show that (a) the effect of land endowment on grain output vary across the east and the west, and between coastal and inland areas; (b) the effect of labor endowment on grain output are inconsistent in the sign and magnitude of the estimates across counties; (c) the effect of agricultural capital on grain production shows heterogeneity spatially (across the east and the west) and economically (across developed and less developed regions). We then analyze the potential mechanism behind this spatial heterogeneity, as well as its policy implications.

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