We evaluated the immune response to infection with a pathogen in large yellow croaker(Pseudosciaena crocea Richardson).The fish were given an intraperitoneal(i.p.) injection of Vibrio parahaemolyticus or sterile sea water(control).We collected blood sera from the fish 0.17,1,2,4,8,12,or 16 d after injection(dpi).We measured tyrosinase activity and the concentrations of lysozyme,NOS,and antibodies.Serum tyrosinase activity was significantly higher at 0.17 and 4 dpi than in the control group,and peaked at 8 d... 相似文献
Large-scale instabilities of mid-latitude jets (with continuous horizontal and vertical shear) are studied using a long wave approximation, which is valid for disturbances of length scales greater than the internal Rossby radius of deformation. These large-scale instabilities are abundant in the Kuroshio Extension according to observations. Results show westward propagation if the total transport is westward (although the jet near surface is eastward). Large-scale instabilities gain energy from the release of available potential energy, but lose part of the gain to the mean flow by reinforcing the eastward jet near surface. The Reynolds stress tends to be positive north of the jet and negative south of the jet through all depths, which is consistent with observations. 相似文献
Two deep channels that cut through the Luzon Strait facilitate deep (>2000 m) water exchange between the western Pacific Ocean
and the South China Sea. Our observations rule out the northern channel as a major exchange conduit. Rather, the southern
channel funnels deep water from the western Pacific to the South China Sea at the rate of 1.06 ± 0.44 Sv (1 Sv = 106 m3s−1). The residence time estimated from the observed inflow from the southern channel, about 30 to 71 years, is comparable to
previous estimates. The observation-based estimate of upwelling velocity at 2000 m depth is (1.10 ± 0.33) × 10−6 ms−1, which is of the same order as Ekman pumping plus upwelling induced by the geostrophic current. Historical hydrographic observations
suggest that the deep inflow is primarily a mixture of the Circumpolar Deep Water and Pacific Subarctic Intermediate Water.
The cold inflow through the southern channel offsets about 40% of the net surface heat gain over the South China Sea. Balancing
vertical advection with vertical diffusion, the estimated mean vertical eddy diffusivity of heat is about 1.21 × 10−3 m2s−1. The cold water inflow from the southern channel maintains the shallow thermocline, which in turn could breed internal wave
activities in the South China Sea. 相似文献
Dissolved and particulate 234Th activities in surface seawater were determined at 27 stations along the coastline of western Taiwan during 19–23 November
2004. Contrasting scavenging settings were observed between the northern and southern regimes of the nearshore water off western
Taiwan, separated by the Cho-Shui River. The northern regime is characterized by a large quantity of suspended load contributed
by northward transport of a suspension plume from the Cho-Shui River, while the southern regime, low in suspended load and
high in chlorophyll concentration, is a system controlled by biological activity. A scavenging model that takes account of
the physical transport was used to estimate the 234Th budget in order to estimate the scavenging and removal rates from the nearshore water. The scavenging and removal rates
ranged from 21 to 127 dpm m−3d−1 and from 36 to 525 dpm m−3d−1, for dissolved and particulate 234Th, respectively. The removal fluxes of particulate organic carbon (POC) and particulate organic nitrogen (PON) were estimated
by multiplying the particulate 234Th removal flux to the organic carbon/234Th and nitrogen/234Th ratios in suspended particles, which ranged from 4.5 to 275.2 mmol-C m−2d−1 and from 1.3 to 50.1 mmol-N m−2d−1, respectively. These fluxes resulted in residence times of 1∼20 days for the POC in the surface water of nearshore water
off western Taiwan. 相似文献
The mafic dykes (dolerites) during the Early Paleozoic are widely spread in Langao-Ziyang, southern Qiling Block, and the investigation on these dykes are very important. Previous studies have mainly focused on the Silurian mafic dykes; however, research on the Earlier Paleozoic mafic dykes is relatively weak at present. Therefore, the overall understanding of the mantle source and genetic dynamic setting during the Early Paleozoic in this area is lacking. To study the accurate age and origin of the Early Paleozoic mafic dykes in Ziyang, southern Shaanxi Province, the mafic dykes from dabacunand Qinmingzhai were selected and the petrology, zircon U–Pb chronology, geochemistry, and Sr–Nd–Hf isotopes were studied. Analysis indicates that the mafic dykes studied are mainly composed of dolerite, and they are the products of the Early Ordovician (475.8–480.7 Ma). Furthermore, the dolerites belong to alkaline rock series, and they are characterized by enrichment in LREE, Rb, Ba, Sr, Nb, (87Sr/86Sr)i = 0.7020–0.7050, εNd(t) = 3.0–4.0), εHf (t) = 4.5–12.1,176Hf/177Hf = 0.282681–0.282844. This suggests that the mafic dyke were derived from the partial melting of a depleted lithospheric mantle, and the genetic process is mainly controlled by the mantle plume based on the discussion of the genetic model. Furthermore, the genetic process experienced the separation and crystallization of olivine and clinopyroxene at the same time, with little crustal contamination.