Teleportation and thermal entanglement in two-qubit Heisenberg XYZ spin chain with the Dzyaloshinski—Moriya interaction and the inhomogeneous magnetic field

This paper studies the average fidelity of teleportation and thermal entanglement for a two-qubit Heisenberg XYZ chain in the presence of both an inhomogeneous magnetic field and a Dzyaloshinski--Moriya interaction. It shows that for a fixed D_z, the increase of b_z will broaden the critical temperature at the cost of decreasing the thermal entanglement. And it can modulate the inhomogeneous magnetic field and the Dzyaloshinski--Moriya interaction for the average fidelity of teleportation to be optimal.     

Study on interaction between the coastal water, shelf water and Kuroshio water in the Huanghai Sea and East China Sea

The main processes of interaction between the coastal water, shelf water and Kuroshiowater in the Huanghai Sea (HS) and East China Sea (ECS) are analyzed based on the observation and study results in recent years. These processes include the intrusion of the Kuroshio water into the shelf area of the ECS, the entrainment of the shelf water into the Kuroshio, the seasonal process in the southern shelf area of the ECS controlled alternatively by the Taiwan Strait water and the Kuroshio water intruding into the shelf area, the interaction between the Kuroshio branch water, shelf mixed water and modified coastal water in the northeastern ECS, the water-exchange between the HS and ECS and the spread of the Changjiang diluted water.     

Comparison between relay propagation and direct propagation of Gaussian—Schell-model beam in turbulent atmosphere along a slant path

The relay propagation of Gaussian--Schell-model in turbulent atmosphere along a slant path is studied in this paper. Based on the extended Huygens--Fresnel principle and a quadratic approximation, an analytical formula of average intensity for Gaussian--Schell-model beams in turbulent atmosphere along a slant path is derived, and some special cases are discussed. From the study and the comparison with the direct propagation, we can see that the relay propagation has an advantage over the direct propagation. When the altitude of the target is low, the peak intensity of relay propagation is much larger than that of direct propagation. However, because of the limitation of the relay system aperture for relay propagation and the variation of coherence length for direct propagation, the difference in peak intensity between the two propagations decreases with the increase of the target altitude.     

Geology and hydrocarbon accumulations in the deepwater of the northwestern South China Sea——with focus on natural gas

The deepwater of the northwestern South China Sea is located in the central to southern parts of the Qiongdongnan Basin(QDN Basin),which is a key site for hydrocarbon exploration in recent years.In this study,the authors did a comprehensive analysis of gravity-magnetic data,extensive 3D seismic survey,cores and cuttings,paleontology and geochemical indexes,proposed the mechanism of natural gas origin,identified different oil and gas systems,and established the model of hydrocarbon accumulations in the deep-water region.Our basin tectonic simulation indicates that the evolution of QDN Basin was controlled by multiple-phased tectonic movements,such as Indochina-Eurasian Plate collision,Tibetan Uplift,Red River faulting and the expansion of the South China Sea which is characterized by Paleogene rifting,Neogene depression,and Eocene intensive faulting and lacustrine deposits.The drilling results show that this region is dominated by marineterrestrial transitional and neritic-bathyal facies from the early Oligocene.The Yacheng Formation of the early Oligocene is rich in organic matter and a main gas-source rock.According to the geological-geochemical data from the latest drilling wells,Lingshui,Baodao,Changchang Sags have good hydrocarbon-generating potentials,where two plays from the Paleogene and Neogene reservoirs were developed.Those reservoirs occur in central canyon structural-lithologic trap zone,Changchang marginal trap zone and southern fault terrace of Baodao Sag.Among them,the central canyon trap zone has a great potential for exploration because the various reservoirforming elements are well developed,i.e.,good coal-measure source rocks,sufficient reservoirs from the Neogene turbidity sandstone and submarine fan,faults connecting source rock and reservoirs,effective vertical migration,late stage aggregation and favorable structural–lithological composite trapping.These study results provide an important scientific basis for hydrocarbon exploration in this region,evidenced by the recent discovery of the significant commercial LS-A gas field in the central canyon of the Lingshui Sag.     

Connection between trace metals,chelators and red tide blooms in the Laholm Bay,SE kattegat—an experimental approach

The influence of the trace metals, copper, aluminum and iron, and of the strong complexing agents, EDTA and NTA, on phytoplankton growth in water from a brackish water bay was investigated through bioassay experiments. A diatom (Skeletonema costatum (Grev.) Cleve) and a dinoflagellate (Prorocentrum minimum (Pav.) J. Schiller) were used as test organisms. The growth of both phytoplankton species was strongly inhibited by copper. This inhibition was generally eliminated by EDTA and NTA. Both phytoplankton species were considerably less inhibited by aluminum than by copper at the same total metal concentration. While S. costatum responded to copper and chelator additions in the same way in sea water samples from different seasons, the growth of P. minimum exhibited pronounced seasonal variation. Other parameters than the values of pCu must be considered in order to account for the experimental results. This work supports the theory that alterations in contents of trace metals and natural chelators in sea water are important factors behind shifts in phytoplankton species composition.     

Fatty acids associated with the frustules of diatoms and their fate during degradation—A case study in Thalassiosira weissflogii

Diatoms are major actors in the export of organic carbon out of the euphotic zone. Yet, the processes linking biogenic silica and carbon sedimentation fluxes to deep oceanic layers remain unclear. Analysing organic fractions in biominerals is challenging because efficient cleaning often led to structural alteration of organic molecules. Hence, although lipids are widely used as biogeochemical markers in ocean flux study, few studies have dealt with the lipids that are associated with frustules. In the present study, a protocol was set up to extract and quantify the fatty acids associated to the frustule of the diatom species Thalassiosira weissflogii. The protocol involves solvent extraction of diatom external lipids, followed by clean frustule dissolution by 4% NaOH during 1 h at 95 °C and subsequent solvent re-extraction of frustule-associated lipids. Results confirmed that this protocol was efficient first, to isolate the frustule from the rest of the cellular organic carbon and second to extract and quantify fatty acids (FA) associated to frustules of this species. FA composition of the frustules was significantly different from that of the whole cells consisting primarily of 14:0, 16:0 and 18:0 FA, as well as a smaller portion of 16:1 and 18:1 unsaturated FA. Frustule-associated FA constituted 7% of the total FA and 1.8% of the total POC. The 30 days T. weissflogii degradation/dissolution experiment suggested that frustule FA 14:0 and 16:0 were mainly associated with the bSiO₂ phase dissolving slowly as no degradation of this pool was measured despite 78% frustule dissolution. At the end of the degradation experiment, this pool constituted 5.8% of the remaining total POC suggesting an effective protection by the frustule through strong interaction with the biogenic silica which is consistent with the correlation observed at depth between Si and POC sedimentation fluxes.     

Variability of the bottom-simulating reflector (BSR) and its association with tectonic structures in the Chilean margin between Arauco Gulf (37°S) and Valdivia (40°S)

Multichannel seismic reflection data recorded between Arauco Gulf (37°S) and Valdivia (40°S), on the Chilean continental margin, were processed and modeled to obtain seismic images and sub-surface models, in order to characterize the variability of the bottom-simulating reflector (BSR), which is a geophysical marker for the presence of gas hydrates. The BSR is discontinuous and interrupted by submarine valleys, canyons, as well as by faults or fractures. The BSR occurrence is more common south of Mocha Island due to moderate slopes and greater organic matter contribution by rivers in that area. Tectonic uplift and structural instability change the stability gas hydrate zone and consequently the BSR position, creating in some cases missing or double BSRs. Our modeling supports the presence of gas hydrate above the BSR and free gas below it. Higher BSR amplitudes support higher hydrate or free gas concentrations. In the study area, gas hydrate concentration is low (an average of 3.5%) suggesting disseminated gas hydrate distribution within the sediments. Also higher BSR amplitudes are associated with thrust faults in the accretionary prism, which serve as conduits for gas flow from deeper levels. This extra gas supply produces a wider thickness of gas hydrates or free gas.     

Fishery livelihoods and (non-)compliance with fishery regulations—A case study in Ca Mau Province,Mekong Delta,Viet Nam

Fishery in Ca Mau, Viet Nam’s most southern province in the Mekong Delta, plays locally an important role for human nutrition and has great potentials for export earnings. The overexploitation of inshore fishing resources is a major problem in Viet Nam’s coastal areas along the Mekong Delta. As a result, the Catch per Unit of Effort of small-scale fishing enterprises has decreased, undermining the sustainability of livelihoods of fishing families. The paper focuses on livelihoods’ strategies and diversification in the context of overexploitation and exhaustion of near-shore resources in relation to fishery policies. The results show that overexploitation is unavoidable in near-shore waters because of the lack of enforcement of fishery regulations for offshore vessels and the limitation of alternative sources of income and opportunities for livelihood diversification for small-scale fishers. The present policies to prevent overexploitation need to be reconciled with livelihood sustainability and fishery management, resource conservation and socio-economic goals     

Midwater fishes in the eastern North Atlantic—I. Vertical distribution and associated biology in 30°N, 23°W,with developmental notes on certain myctophids

This paper is the first of a series describing the vertical distribution of midwater fishes in the eastern North Atlantic in areas approximately 10° of latitude apart near the 20° meridian. As such, it is concerned solely with collections made in 30°N, 23°W. The results are based primarily upon RMT 8 net samples collected using an opening-closing RMT 1+8 combination net. In all, 17,443 specimens were caught by RMT 8, divisible into 37 families, 66 genera with 98 species identified. Numerically the most abundant groups recognized were the Gonostomatidae (60% total catch), Macrorhamphosidae (23%) and Myctophidae (7%). Some definition of vertical limits is provided for the majority of species represented, but only 31 are considered in detail. Where possible, observed biological phenomena (e.g. development, sexual maturity, sexual dimorphism, etc.) and distribution limits have been correlated. In general, the characteristics of species' distributions, and the observed relations of distribution and migratory behaviour were as one would anticipate from past work. Among many species, a size-depth stratification was observed, and with migrants, migratory behaviour appeared dependent upon developmental state. The mode of species development, however, had no bearing upon ultimate migratory behaviour. Certain non-migratory elements of the population of an habitually migrant species, e.g. Chauliodus danae, could not be satisfactorily interpreted upon the basis of biological factors examines. Migrant species principally occupied 400–900 m depth by day, and 25–300 m by night, although they occurred at greater depths. Reverse migrations were only observed in Macrorhamphosus. The overall catches were dominated by non-migrants, and at depths greater that 200 m these comprised the most abundant species per depth at all times. Cyclothone constituted the most abundant genus sampled and provided greatest insight into distributional and biological detail. C. braueri, the most numerous species, is probably a single spawner, and the results demonstrate a size-depth stratification that may be correlated with sexual maturity stages. The olfactory structure in males is more complicated than previously described. The larger males develop a snout prolongation which would improve water flow through the nasal rosette and hence olfaction. Unlike C. microdon, C. braueri probably does not undergo sex-reversal. Developmental notes are included for the myctophid species Notoscopelus resplendens, Benthosema suborbitale, and Hygophum hygomi in the Appendix.     

Diagenesis and reservoir quality of sandstones with ancient “deep” incursion of meteoric freshwater——An example in the Nanpu Sag,Bohai Bay Basin,East China

An example of diagenesis and reservoir quality of buried sandstones with ancient incursion of meteoric freshwater is presented in this study. The interpretation is based on information including porosity and permeability, petrography, stable isotopic composition of authigenic minerals, homogenization temperatures (T_h) of aqueous fluid inclusions (AFIs), and pore water chemistry. These sandstones, closely beneath or far from the regional unconformity formed during the late Paleogene period, are located in the thick Shahejie Formation in the Gaoliu area of Nanpu Sag, Bohai Bay Basin, East China. Early-diagenetic calcite cements were leached to form intergranular secondary pores without precipitation of late-diagenetic calcite cements in most sandstones. Feldspars were leached to form abundant intragranular secondary pores, but with small amounts of concomitant secondary minerals including authigenic quartz and kaolinite. The mass imbalance between the amount of leached minerals and associated secondary minerals suggests that mineral leaching reactions occurred most likely in an open geochemical system, and diagenetic petrography textures suggest that advective flow dominated the transfer of solutes from leached feldspars and calcites. Low salinity and ion concentrations of present pore waters, and extensive water rock interactions suggest significant incursion of meteoric freshwater flux in the sandstones. Distances of the sandstones to the regional unconformity can reach up to 1800 m, while with significant uplift in the Gaoliu area, the burial depth of such sandstones (below sea level) can be less than 800–1000 m during the uplift and initial reburial stage. Significant uplift during the Oligocene period provided substantial hydraulic drive and widely developed faults served as favorable conduits for downward penetration of meteoric freshwater from the earth's surface (unconformity) to these sandstone beds. Extensive feldspar leaching has been occurring since the uplift period. Coupled high T_h (95∼115 °C) of AFI and low δ¹⁸O_(SMOW) values (+17∼+20‰) within the quartz overgrowths show that quartz cementation occurred in the presence of diagenetic modified meteoric freshwater with δ¹⁸O_(SMOW) values of −7∼−2‰, indicating that authigenic quartz only have been formed during the late reburial stage when meteoric fresh water penetration slowed down. Secondary pores in thin sections and tested porosity suggest that meteoric freshwater leaching of feldspars and calcite minerals generated approximately 7–10% enhanced secondary porosity in these sandstones. Meteoric freshwater leaching reactions cannot be ignored in similar sandstones that located deep beneath the unconformity, with great uplift moving these sandstones above or close to sea level and with faults connecting the earth's surface with the sandstone beds.