The variability of ocean circulation and sea surface temperature (SST) in the tropical Atlantic, especially in the Gulf of Guinea (GG), defines this region as exceptionally rich from an oceanographic perspective. The ...The variability of ocean circulation and sea surface temperature (SST) in the tropical Atlantic, especially in the Gulf of Guinea (GG), defines this region as exceptionally rich from an oceanographic perspective. The Guinea Current (GC), as the major surface current, plays a significant role in marine productivity and coastal upwelling in the GG. This coastal upwelling is known to influence the climate of the surrounding region, primary productivity and local fisheries. Studies on GC variability and its impact on this coastal upwelling have highlighted that the upwelling downstream of Cape Palmas is influenced by GC detachment, topographic variations and advective processes leading to significant vertical mixing. This study aims to analyze the interannual variability of the GC and its impact on coastal upwelling using the Coastal and Regional Ocean COmmunity model (CROCO). The model’s evaluation is conducted using observational data, specifically Geostrophic and EKman Current Observatory (GEKCO) and Ocean Surface Current Analysis (OSCAR) for currents, and Air-sea Fluxes for the global Tropic ocean-description (TROPFLUX) and Optimum Interpolation-Sea Surface Temperature (OI-SST) for temperature. Thus, the model evaluation indicates that it accurately replicates ocean circulation and SST patterns in the tropical Atlantic and the GG. The joint analysis of upwelling indices (surface and intensity) and the position of the GC core allowed us to conclude that the displacement of the GC core does indeed influence the upwelling indices in the northern part of GG. However, other oceanic and atmospheric mechanisms such as vertical diffusion and horizontal advection as proposed by previous studies may also affect the year-by-year variability of coastal upwelling in the northern GG.展开更多
The whole-cell patch-clamp technique was employed to obtain information about the voltage-dependence and kinetics of interaction of 7-chlor-benzylte-trahydropalmatine (7-Cl-BTHP) with cardiac sodium channels. 7-Cl-BTH...The whole-cell patch-clamp technique was employed to obtain information about the voltage-dependence and kinetics of interaction of 7-chlor-benzylte-trahydropalmatine (7-Cl-BTHP) with cardiac sodium channels. 7-Cl-BTHP (30 mol/L) significantly decreased the peak sodium current (from 7. 8±1. 8 nA to 5. 3±1. 4 nA, P<0. 01, n=5), without producing a shift of the current-voltage curve. It shifted the inactivation curves of sodium current to hyperpolarized potentials, and the V(0.5) was shifted from - (82. 5±2. 5) mV to - (95±2.4) mV (P <0. 05, n=4). 7-Cl-BTHP produced a significant use-dependent effect that was proportional to the duration of the voltage step. In addition, 7-Cl-BTHP slowed the recovery of sodium channel from inactivation, which could explain its use-dependent effects on sodium current. The characteristics of 7-Cl-BTHP blockage suggest that this agent binds preferentially to inactivated sodium channels.展开更多
文摘The variability of ocean circulation and sea surface temperature (SST) in the tropical Atlantic, especially in the Gulf of Guinea (GG), defines this region as exceptionally rich from an oceanographic perspective. The Guinea Current (GC), as the major surface current, plays a significant role in marine productivity and coastal upwelling in the GG. This coastal upwelling is known to influence the climate of the surrounding region, primary productivity and local fisheries. Studies on GC variability and its impact on this coastal upwelling have highlighted that the upwelling downstream of Cape Palmas is influenced by GC detachment, topographic variations and advective processes leading to significant vertical mixing. This study aims to analyze the interannual variability of the GC and its impact on coastal upwelling using the Coastal and Regional Ocean COmmunity model (CROCO). The model’s evaluation is conducted using observational data, specifically Geostrophic and EKman Current Observatory (GEKCO) and Ocean Surface Current Analysis (OSCAR) for currents, and Air-sea Fluxes for the global Tropic ocean-description (TROPFLUX) and Optimum Interpolation-Sea Surface Temperature (OI-SST) for temperature. Thus, the model evaluation indicates that it accurately replicates ocean circulation and SST patterns in the tropical Atlantic and the GG. The joint analysis of upwelling indices (surface and intensity) and the position of the GC core allowed us to conclude that the displacement of the GC core does indeed influence the upwelling indices in the northern part of GG. However, other oceanic and atmospheric mechanisms such as vertical diffusion and horizontal advection as proposed by previous studies may also affect the year-by-year variability of coastal upwelling in the northern GG.
文摘The whole-cell patch-clamp technique was employed to obtain information about the voltage-dependence and kinetics of interaction of 7-chlor-benzylte-trahydropalmatine (7-Cl-BTHP) with cardiac sodium channels. 7-Cl-BTHP (30 mol/L) significantly decreased the peak sodium current (from 7. 8±1. 8 nA to 5. 3±1. 4 nA, P<0. 01, n=5), without producing a shift of the current-voltage curve. It shifted the inactivation curves of sodium current to hyperpolarized potentials, and the V(0.5) was shifted from - (82. 5±2. 5) mV to - (95±2.4) mV (P <0. 05, n=4). 7-Cl-BTHP produced a significant use-dependent effect that was proportional to the duration of the voltage step. In addition, 7-Cl-BTHP slowed the recovery of sodium channel from inactivation, which could explain its use-dependent effects on sodium current. The characteristics of 7-Cl-BTHP blockage suggest that this agent binds preferentially to inactivated sodium channels.
