Rotation numbers of invariant manifolds around unstable periodic orbits for the diamagnetic Kepler problem

In this paper, a method to construct topological template in terms of symbolic dynamics for the diamagnetic Kepler problem is proposed. To confirm the topological template, rotation numbers of invariant manifolds around unstable periodic orbits in a phase space are taken as an object of comparison. The rotation numbers are determined from the definition and connected with symbolic sequences encoding the periodic orbits in a reduced Poincar\'e section. Only symbolic codes with inverse ordering in the forward mapping can contribute to the rotation of invariant manifolds around the periodic orbits. By using symbolic ordering, the reduced Poincar\'e section is constricted along stable manifolds and a topological template, which preserves the ordering of forward sequences and can be used to extract the rotation numbers, is established. The rotation numbers computed from the topological template are the same as those computed from their original definition.Comment: 8 figures, 1 tabl

Streamline topology and dilute particle dynamics in a Karman vortex street flow

Three types of streamline topology in a Karman vortex street flow are shown under the variation of spatial parameters. For the motion of dilute particles in the K\'arm\'an vortex street flow, there exist a route of bifurcation to a chaotic orbit and more attractors in a bifurcation diagram for the proportion of particle density to fluid density. Along with the increase of spatial parameters in the flow filed, the bifurcation process is suspended, as well as more and more attractors emerge. In the motion of dilute particles, a drag term and gravity term dominate and result in the bifurcation phenomenon.Comment: 16 pages, 9 figure

Harnessing optical micro-combs for microwave photonics

In the past decade, optical frequency combs generated by high-Q micro-resonators, or micro-combs, which feature compact device footprints, high energy efficiency, and high-repetition-rates in broad optical bandwidths, have led to a revolution in a wide range of fields including metrology, mode-locked lasers, telecommunications, RF photonics, spectroscopy, sensing, and quantum optics. Among these, an application that has attracted great interest is the use of micro-combs for RF photonics, where they offer enhanced functionalities as well as reduced size and power consumption over other approaches. This article reviews the recent advances in this emerging field. We provide an overview of the main achievements that have been obtained to date, and highlight the strong potential of micro-combs for RF photonics applications. We also discuss some of the open challenges and limitations that need to be met for practical applications.Comment: 32 Pages, 13 Figures, 172 Reference

A high sensitivity iron-dependent bioreporter used to measure iron bioavailability in freshwaters

A Nostoc sp. PCC 7120 iron bioreporter containing iron-regulated schizokinen transporter gene alr0397 promoter fused to the luxAB genes was examined to optimize its response to bioavailable iron. Doseresponse relationships between luciferase activity and free ferric ion (Fe3+) concentrations pFe (-lg [Fe3+]) were generated by measuring luciferase activities of the bioreporter in trace metalbuffered Fraquil medium with various incubation times. The results were best demonstrated by sigmoidal curves (pFe 18.821.7, Fe3+ = 10-18.810-21.7 M) with the linear range extending from pFe 19.621.5 (Fe3+ = 10-19.610-21.5 M) after a 12-h incubation time. Optimal conditions for the use of this bioreporter to sense the iron bioavailability were determined to be: a 12-h exposure time, initial cell density of OD730 nm = 0.06, high nitrate (100 mu M), high phosphate (10 mu M), moderate Co2+ (0.122.5 nM), Zn2+ (0.1612 nM), Cu2+ (0.0450 nM), and wide range of Mn2+ concentration (0.922300 nM). The applicability of using this iron bioreporter to assess iron availability in the natural environment has been tested using water samples from eutrophic Taihu, Donghu, and Chaohu lakes. It is indicated that the bioreporter is a useful tool to assess bioavailable iron in various water quality samples, especially in eutrophic lakes with high bioavailable iron.A Nostoc sp. PCC 7120 iron bioreporter containing iron-regulated schizokinen transporter gene alr0397 promoter fused to the luxAB genes was examined to optimize its response to bioavailable iron. Doseresponse relationships between luciferase activity and free ferric ion (Fe3+) concentrations pFe (-lg [Fe3+]) were generated by measuring luciferase activities of the bioreporter in trace metalbuffered Fraquil medium with various incubation times. The results were best demonstrated by sigmoidal curves (pFe 18.821.7, Fe3+ = 10-18.810-21.7 M) with the linear range extending from pFe 19.621.5 (Fe3+ = 10-19.610-21.5 M) after a 12-h incubation time. Optimal conditions for the use of this bioreporter to sense the iron bioavailability were determined to be: a 12-h exposure time, initial cell density of OD730 nm = 0.06, high nitrate (100 mu M), high phosphate (10 mu M), moderate Co2+ (0.122.5 nM), Zn2+ (0.1612 nM), Cu2+ (0.0450 nM), and wide range of Mn2+ concentration (0.922300 nM). The applicability of using this iron bioreporter to assess iron availability in the natural environment has been tested using water samples from eutrophic Taihu, Donghu, and Chaohu lakes. It is indicated that the bioreporter is a useful tool to assess bioavailable iron in various water quality samples, especially in eutrophic lakes with high bioavailable iron

A niche model to predict Microcystis bloom decline in Chaohu Lake, China

Cyanobacterial blooms occur frequently in lakes due to eutrophication. Although a number of models have been proposed to forecast algal blooms, a good and applicable method is still lacking. This study explored a simple and effective mathematical-ecological model to evaluate the growth status and predict the population dynamics of Microcystis blooms. In this study, phytoplankton were collected and identified from 8 sampling sites in Chaohu Lake every month from July to October, 2010. The niche breadth and niche overlap of common species were calculated using standard equations, and the potential relative growth rates of Microcystis were calculated as a weighted-value of niche overlap. In July, the potential relative growth rate was 2.79 (a.u., arbitrary units) but then rapidly declined in the following months to -3.99 a.u. in September. A significant correlation (R =0.998, P < 0.01) was found in the model between the net-increase in biomass of Microcystis in the field and the predicted values calculated by the niche model, we concluded that the niche model is suitable for forecasting the dynamics of Microcystis blooms. Redundancy analysis indicated that decreases in water temperature, dissolved oxygen and total dissolved phosphorus might be major factors underlying bloom decline. Based on the theory of community succession being caused by resource competition, the growth and decline of blooms can be predicted from a community structure. This may provide a basis for early warning and control of algal blooms.Cyanobacterial blooms occur frequently in lakes due to eutrophication. Although a number of models have been proposed to forecast algal blooms, a good and applicable method is still lacking. This study explored a simple and effective mathematical-ecological model to evaluate the growth status and predict the population dynamics of Microcystis blooms. In this study, phytoplankton were collected and identified from 8 sampling sites in Chaohu Lake every month from July to October, 2010. The niche breadth and niche overlap of common species were calculated using standard equations, and the potential relative growth rates of Microcystis were calculated as a weighted-value of niche overlap. In July, the potential relative growth rate was 2.79 (a.u., arbitrary units) but then rapidly declined in the following months to -3.99 a.u. in September. A significant correlation (R =0.998, P < 0.01) was found in the model between the net-increase in biomass of Microcystis in the field and the predicted values calculated by the niche model, we concluded that the niche model is suitable for forecasting the dynamics of Microcystis blooms. Redundancy analysis indicated that decreases in water temperature, dissolved oxygen and total dissolved phosphorus might be major factors underlying bloom decline. Based on the theory of community succession being caused by resource competition, the growth and decline of blooms can be predicted from a community structure. This may provide a basis for early warning and control of algal blooms

Sinigarra napoense, a new genus and species of labeonin fishes (Teleostei: Cyprinidae) from Guangxi Province, South China

A new garrain genus and species are described from the Zuo-Jiang of the Zhu-Jiang (Pearl River) drainage in Guangxi Province, South China. Sinigarra, new genus, is characterized by having the lower lip modified into a mental adhesive disc posteriorly discontinuous with the mental region. It is distinguished from all other disc-bearing genera, namely Garra, Placocheilus, Discocheilus and Discogobio, by having the anterior edge of the mental adhesive disc not modified to form an anteromedian crescentic fold, an upper lip present, but separated from the upper jaw, and indistinct papillae scarcely scattered over the rostral cap and lower lip or absent.A new garrain genus and species are described from the Zuo-Jiang of the Zhu-Jiang (Pearl River) drainage in Guangxi Province, South China. Sinigarra, new genus, is characterized by having the lower lip modified into a mental adhesive disc posteriorly discontinuous with the mental region. It is distinguished from all other disc-bearing genera, namely Garra, Placocheilus, Discocheilus and Discogobio, by having the anterior edge of the mental adhesive disc not modified to form an anteromedian crescentic fold, an upper lip present, but separated from the upper jaw, and indistinct papillae scarcely scattered over the rostral cap and lower lip or absent

Diffusion dominated process for the crystal growth of a binary alloy

The pure diffusion process has been often used to study the crystal growth of a binary alloy in the microgravity environment. In the present paper, a geometric parameter, the ratio of the maximum deviation distance of curved solidification and melting interfaces from the plane to the radius of the crystal rod, was adopted as a small parameter, and the analytical solution was obtained based on the perturbation theory. The radial segregation of a diffusion dominated process was obtained for cases of arbitrary Peclet number in a region of finite extension with both a curved solidification interface and a curved melting interface. Two types of boundary conditions at the melting interface were analyzed. Some special cases such as infinite extension in the longitudinal direction and special range of Peclet number were reduced from the general solution and discussed in detail

Thiol-Functionalized Mesoporous Silica for Effective Trap of Mercury in Rats

The chance of exposure to heavy metal for human being rises severely today due to the increasing water contamination and air pollution. Here, we prepared a series of thiol-functionalized mesoporous silica as oral formulation for the prevention and treatment of heavy metal poisoning. The successful incorporation of thiol was verified by the FTIR spectra. SBA15-SH-10 was used for the study as it is of uniform mesopores and fine water dispersibility. In simulated gastrointestinal fluid, the thiol-functionalized mesoporous silica can selectively capture heavy metal, showing a very high affinity for inorganic mercury (II). The blood and urine mercury levels of rats fed with a diet containing Hg (II) and material were significantly lower than those of rats fed with the metal-rich diet only. On the contrary, the mercury content in fecal excretion of the treatment group increased more than twice as much as that of the control group. This result indicated that SBA15-SH-10 could effectively remove mercury (II) in vivo and the mercury loaded on SBA15-SH-10 would be excreted out. Hence, SBA15-SH-10 has potential application in preventing and treating heavy metal poisoning via digestive system

Characteristics of Sediment Bacterial Community in Response to Environmental Impacts in a Sewage Polluted River

The Jiaolai River is the main source of industrial and irrigation water for its catchment of 3900 km(2). Anthropogenic activities have caused heavy pollution of this river, but their impacts on biota have never been evaluated. In this study, molecular techniques were applied to investigate the impacts of environmental pollution on the river. Quantitative PCR revealed that total bacterial abundance ranged from 2.90x10(7) to 2.12x10(8) copies/g, with no significant differences among sampling sites or seasons. Bacterial abundance and pore water ammonium concentration were negatively correlated. Cluster analysis revealed that bacterial communities were mainly distributed into groups corresponding to nitrate concentration. Two clone libraries were constructed to compare the bacterial composition of samples with high (J308) and moderate (J304) nitrate impact. Sample J308 was characterized by more members in Clostridia and disappearance of Betaproteobacteria members, which are the primary contributors to nitrogen biogeochemical cycling. Bacterial communities in the sediment were clearly differentiated by environmental nitrogen pollution, suggesting that nitrogen eutrophication was the main environmental problem influencing the Jiaolai River