The abundance and community composition of phytoplankton are influenced by a suite of interacting environmental factors. Hong Kong's marine environment features a hydrographic gradient from an ...estuarine zone in the west to a transition zone in the middle and an oceanic zone in the east. Size fractionation combined with high performance liquid chromatography (HPLC) pigment analyses were used to investigate the phytoplankton communities in different hydrographic zones during summer (July–August 2009) and winter (December 2009–January 2010). Clear temporal and spatial variations in environmental parameters occurred among hydrographic zones. Results of principal component analysis (PCA) revealed that the major deviating factors among hydrographic zones were turbidity and salinity in summer and nitrate and phosphate in winter. Phytoplankton abundance showed significant temporal variations, but no zonal variations. Phytoplankton communities in all hydrographic zones were dominated by cells >5 µm in both summer and winter. Chlorophyll a concentrations for most size fractions correlated significantly with temperature. The high concentration of fucoxanthin indicated that the phytoplankton community was dominated by diatoms in both summer and winter, while dinoflagellates, cryptophytes, cyanobacteria and other minor groups occurred sporadically in low abundance. The spatial pattern of phytoplankton in Hong Kong's coastal seas did not reflect the hydrographic zonation, but the phytoplankton in the semi-enclosed Tolo Harbour and Deep Bay were different from those in the other zones.
The seasonal and spatial occurrences of Chaetognatha were studied in 2 subtropical marine inlets with different hydrographical characteristics. Tolo Harbour and Mirs Bay are marine bays in the ...northeastern corner of Hong Kong. Tolo Harbour is a semi-enclosed bay with poor water circulation. It opens into Mirs Bay which is fully exposed to water currents from the South China Sea. Chaetognath species were grouped by hierarchical classification of samples using the Bray-Curtis similarity coefficient and a clustering strategy with flexible links. Indicator species for each group were used to characterize species assemblages. Indigenous species, including Flaccisagitta enflata, Aidanosagitta neglecta, A. delicata, A. nagae, A. crassa, A. johorensis, and A. regularis, occurred in the entire study area, but their densities were higher in Tolo Harbour. Non-indigenous species, including A. bedfordii, Krohnitta pacifica, Pterosagitta draco, Decipisagitta decipiens, Ferosagitta ferox, Fer. robusta, Fer. tokiokai, Mesosagitta minima, Sagitta bipunctata, Serratosagitta pacifica, Zonosagitta bedoti, Z. bruuni, and Z. pulchra were carried into Mirs Bay by ocean currents from the South China Sea and were rarely found in Tolo Harbour.
Phytoplankton community composition and mesozooplankton selective feeding on different phytoplankton taxa were studied by HPLC pigment analysis at 2 sites with contrasting hydrography in the coastal ...areas of Hong Kong. The site (WE) on the western part of Hong Kong is located in the Pearl River estuary, whereas the site (EO) on the eastern part of Hong Kong is influenced by oceanic waters. Despite the strong difference in hydrographic conditions, diatoms were the dominant phytoplankton at both sites throughout most months of the year, contributing on average more than 40% of the total phytoplankton in terms of chlorophylla(chla). Cryptophytes were the second most abundant phytoplankton group at both sites, whereas contributions from haptophytes, green algae, cyanobacteria and dinoflagellates were small. Diatoms and cryptophytes, the 2 most dominant phytoplankton groups, accounted for about 80 and 75% of the diets of mesozooplankton at EO and WE, respectively. One consistent pattern observed throughout the study period was that mesozooplankton assemblages strongly preferred dinoflagellates over other types of phytoplankton, especially in estuarine waters, even though dinoflagellates only contributed to a small fraction of total chla. On the other hand, phytoplankton groups with relative small cell sizes, such as green algae and cyanobacteria, were not efficiently ingested. Overall, mesozooplankton feeding selectivity in subtropical eutrophic coastal waters, where planktonic food is sufficient, appears to be influenced by a combination of different factors, including the compositions of predators and the size and quality of the prey.
We study the stochastic stability of a dynamic trading process in an exchange economy. We use a simplified version of a trading model
à la
Shapley and Shubik (J Polit Econ 85:937–968,
1977
). Two ...types of agents equipped with Leontief preferences trade goods in markets by offering endowments, and actual trades occur at market clearing prices. Better behavior tends to spread through the same type of agents by imitation, and agents also make mistakes occasionally. We provide a sufficient condition for the perturbed dynamic process to have a unique stochastically stable state that is a Walrasian equilibrium allocation. In this sense, we give a rationale for Walrasian behavior.
A process consisting of e-beam lithography and lift-off was optimized to fabricate metallic nanostructures. This optimized process successfully produced gold and aluminum nanostructures with features ...size less than 20 nm. These structures range from simple parallel lines to complex photonic structures. Optical properties of gold split ring resonators (SRRs) were characterized with Raman spectroscopy. Surface-Enhanced Raman Scattering (SERS) on SRRs was observed with 4-mercaptopyridine (4-MPy) as molecular probe and greatly enhanced Raman scattering was observed.
We show that the predictions of long-run behavior under the evolutionary process are highly sensitive to the addition and elimination of strictly dominated strategies. In particular, for the best ...response dynamics cf. Kandori, M., Rob, R., 1995. Evolution of equilibria in the long run: A general theory and applications. J. Econ. Theory 65 (2), 383–414 we prove that for any symmetric normal form game, any strict Nash equilibrium can be selected as the unique long-run equilibrium by appropriately adding only one single strategy which is strictly dominated by all original strategies. Moreover, if we further assume instantaneous adjustment, then any convex combination of strict Nash equilibria with rational number weights can be realized as the long-run distribution by appropriately adding strictly dominated strategies.
Predatory copepods of the family Euchaetidae are widely distributed in polar, temperate, subtropical and tropical oceans. Paraeuchaeta concinna is the most abundant Euchaetidae in the subtropical ...coastal seas of Hong Kong and southern China. However, compared to Euchaetidae species in temperate and polar regions, relatively little information is available on the ecology of P. concinna and other Euchaetidae species in the subtropical oceans. This paper provides information on the seasonal abundance of P. concinna in the coastal seas of eastern Hong Kong. The diel vertical distribution of P. concinna, feeding behavior, and predation impact on mesozooplankton in eastern Hong Kong were also investigated.
P. concinna is most abundant in winter and spring. Their abundance decreases shoreward, and densities are generally higher in the open waters of eastern Hong Kong than in the inner parts of Mirs Bay and Tolo Harbour. P. concinna exhibits both diel vertical migration and diel feeding rhythms in Mirs Bay. P. concinna females show strong preference for the copepods of the genera Acrocalanus, Paracalanus, and Parvocalanus, and remove ~4% of their standing stocks daily.
The low abundance of P. concinna during most of the year suggests it is not indigenous to coastal seas of eastern Hong Kong. P. concinna performs diel vertical migration, most likely as a strategy to avoid visual predation. Gut content analysis showed that Acrocalanus, Paracalanus, and Parvocalanus are highly preferred prey of P. concinna. A daily predation impact of ~4% of the standing stocks of Acrocalanus, Paracalanus, and Parvocalanus suggests that P. concinna may play an important role in regulating the populations of these small copepods in Mirs Bay, especially during winter and spring.
Predictors of Asian American first‐year college students’ intention to participate in a culturally congruent mentoring program was empirically documented using Ajzen and Fishbein's (1980) theory of ...reasoned action (TRA). Intention to participate was predicted by the belief that participation eases transition to college. Also, attitude toward participation was positively related to students’ beliefs that participation will strengthen ethnic identity and combat model‐minority myth. With 78% of students who intended to participate, results suggest that Asian American college students need programming that addresses issues as first‐year college students and those related to their cultural experience. The use of the TRA to better understand issues related to peer mentoring is illuminated. Wider implications for implementing culturally congruent mentoring programs in educational settings are discussed.
We study the non-cooperative formation of a (directed) network that builds upon one-way immediate links. Our novel feature is that we require circular paths of links for productive activities. This ...captures more clearly the higher level of coordination that is often required for network formations than models such as those of Jackson and Wolinsky A strategic model of social and economic networks, J. Econ. Theory 71 (1996) 44–74 and Bala and Goyal A non-cooperative model of network formation, Econometrica 68 (2000) 1181–1229, in that in our model a single agent's unilateral action is limited in affecting the network structure. We completely characterize the class of Nash equilibria by showing that the minimality of a graph is both necessary and sufficient (Theorem 1). We also propose the concept of a stable network that is similar to the pairwise stability of Jackson and Wolinsky (1996). We show that stable equilibria are a wheel, a trivial network, or a sub-wheel partitioned network (Theorem 2). We modify the Bala and Goyal (2000) dynamic process with inertia, and obtain the convergence to stable equilibria regardless of the initial state (Theorem 3).
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