Modulation Instability and Non-Degenerate Akhmediev Breathers of Manakov Equations

We reveal a special subset of non-degenerate Akhmediev breather(AB)solutions of Manakov equations that only exist in the focusing case.Based on exact solutions,we present the existence diagram of such excitations on the frequency-wavenumber plane.Conventional single-frequency modulation instability leads to simultaneous excitation of three ABs with two of them being non-degenerate.

POLYMERIC SURFACTANT STRUCTURE

Polymeric surfactants are amongst the most widespread of all polymers. In nature, proteins and polysaccharidescause self organization as a result of this surfactancy; in industry, polymeric surfactants play key roles in the food, explosivesand surface coatings sectors. The generation of useful nano- and micro-structures in films and emulsions as a result ofpolymer amphiphilicity and the application of mechanical stress is discussed. The use of X-ray and neutron small anglescattering and reflectivity to measure these structures and their dynamic properties will be described. New results on linear and dendritic polymer surfactants are presented.

The Great Plume Debate

It is forty years since J. Tuzo Wilson first suggested that the Hawaiian Islands were produced by the oceanic lithosphere moving over a stationary ＂hotspot＂ in the mantle, and thirty years since W. Jason Morgan suggested that Wilson＇s hotspots are thermal plumes in the Earth＇s mantle, and that they may play an important role in convection. Flood basalts, volcanic continental margins, large oceanic plateaus and age-progressive aseismic ridges, along with smaller-volume seamount and ocean-island chains, have all been attributed to mantle plumes.

Cross-Correlation of Excitation Functions for Different Fragments and Different Scattering Angles in ^27Al（^19F,x）y Reactions

Excitation functions have been measured for different projectile-like fragments produced in ^27Al（^19F, x ）y reactions at incident energies from 110. 25 to 118. 75 Me V in 250 ke V steps. Strong cross section fluctuations of the excitation functions are observed. The cross-correlation coefficients of the excitation functions for different atomic number Z and for different scattering angle θcm have been deduced. These coefficients are much larger than the statistical theoretical calculated ones. This indicates that there are strong correlations between different exit channels in the dissipative heavy ion collision of ^27Al（^19F, x）y.

质子注入和快速退火对GaAs/AlGaAs量子阱能级结构的调整

本文介绍利用界面混合技术对ＧａＡｓ／ＡｌＧａＡｓ量子阱结构进行微调，通过荧光光谱和光响应电流谱给出了质子注入和快速返火对禁带宽度及导带内子带位置的影响，荧光光谱峰位随注入剂量（５ｘ１０４～５ｘ１０１５ｃｍ２）的增加从７６６ｕｍ持续蓝移至７５３ｕｍ，光响应峰值波长从８．２ｕｍ移至１０．３ｕｍ．

Intelligent metaphotonics empowered by machine learning

In the recent years,a dramatic boost of the research is observed at the junction of photonics,machine learning and artifi-cial intelligence.A new methodology can be applied to the description of a variety of photonic systems including optical waveguides,nanoantennas,and metasurfaces.These novel approaches underpin the fundamental principles of light-matter interaction developed for a smart design of intelligent photonic devices.Artificial intelligence and machine learn-ing penetrate rapidly into the fundamental physics of light,and they provide effective tools for the study of the field of metaphotonics driven by optically induced electric and magnetic resonances.Here we overview the evaluation of meta-photonics induced by artificial intelligence and present a summary of the concepts of machine learning with some specif-ic examples developed and demonstrated for metasystems and metasurfaces.

Introduction of atomic H into Si_3N_4/SiO_2/Si stacks

Atomic H generated by a plasma NH3 source at 400 ℃ was demonstrated to passivate dehydrogenated Si3N4/SiO2/Si stacks effectively by bonding with defects in the Si3N4 film and at the Si-SiO2 interface. A subsequent anneal in N2 after atomic H reintroduction was demonstrated to further improve passivation of the Si-SiO2 interface. Isothermal and isochronal anneals in N2 were carried out in order to determine the optimized annealing conditions.

Nonlinear frequency conversion in optical nanoantennas and metasurfaces:materials evolution and fabrication

Nonlinear frequency conversion is one of the most fundamental processes in nonlinear optics.It has a wide range of applications in our daily lives,including novel light sources,sensing,and information processing.It is usually assumed that nonlinear frequency conversion requires large crystals that gradually accumulate a strong effect.However,the large size of nonlinear crystals is not compatible with the miniaturisation of modern photonic and optoelectronic systems.Therefore,shrinking the nonlinear structures down to the nanoscale,while keeping favourable conversion efficiencies,is of great importance for future photonics applications.In the last decade,researchers have studied the strategies for enhancing the nonlinear efficiencies at the nanoscale,e.g.by employing different nonlinear materials,resonant couplings and hybridization techniques.In this paper,we provide a compact review of the nanomaterials-based efforts,ranging from metal to dielectric and semiconductor nanostructures,including their relevant nanofabrication techniques.

High-speed multiwavelength InGaAs/InP quantum well nanowire array micro-LEDs for next generation optical communications

Miniaturized light sources at telecommunication wavelengths are essential components for on-chip optical communication systems.Here,we report the growth and fabrication of highly uniform p-i-n core-shell InGaAs/InP single quantum well(QW)nanowire array light emitting diodes(LEDs)with multi-wavelength and high-speed operations.Two-dimensional cathodoluminescence mapping reveals that axial and radial QWs in the nanowire structure contribute to strong emission at the wavelength of~1.35 and~1.55μm,respectively,ideal for low-loss optical communications.As a result of simultaneous contributions from both axial and radial QWs,broadband electroluminescence emission with a linewidth of 286 nm is achieved with a peak power of~17μW.A large spectral blueshift is observed with the increase of applied bias,which is ascribed to the band-filling effect based on device simulation,and enables voltage tunable multi-wavelength operation at the telecommunication wavelength range.Multi-wavelength operation is also achieved by fabricating nanowire array LEDs with different pitch sizes on the same substrate,leading to QW formation with different emission wavelengths.Furthermore,high-speed GHz-level modulation and small pixel size LED are demonstrated,showing the promise for ultrafast operation and ultracompact integration.The voltage and pitch size controlled multi-wavelength highspeed nanowire array LED presents a compact and efficient scheme for developing high-performance nanoscale light sources for future optical communication applications.

Optical properties of phosphorene

Phosphorene is a two-dimensional semiconductor with layers-dependent bandgap in the near-infrared range and it has attracted a great deal of attention due to its high anisotropy and cartier mobility. The highly anisotropic nature of phos- phorene has been demonstrated through Raman and polarization photoluminescence measurements. Photoluminescence spectroscopy has also revealed the layers-dependent bandgap of phosphorene. Furthermore, due to the reduced dimension- ality and screening in phosphorene, excitons and trions can stably exist at elevated temperatures and have large binding energies. The exciton and trion dynamics are thus detected by applying electrical bias or optical injection to the phospho- rene system. Finally, various optical and optoelectronic applications based on phosphorene have been demonstrated and discussed.

Induced Fission-Like Process of Hadronic Molecular States

We predict a new physical phenomenon,induced fission-like process and chain reaction of hadronic molecular states.As a molecular state,if induced by a D meson,the X(3872)can split into D■final state which is forbidden due to the spin-parity conservation.The breeding of the D meson of the reaction,such as D^(0)X(3872)→D^(0)■0D^(0),makes the chain reaction of X(3872)matter possible.We estimate the cross section of the D meson induced fission-like process of X(3872)into two D mesons.With very small D^(0) beam momentum of 1 e V,the total cross section reaches an order of 1000 b,and decreases rapidly with the increasing beam momentum.With the transition of D^(*)meson in molecular states to a D meson,the X(3872)can release large energy,which is acquired by the final mesons.The momentum distributions of the final D mesons are analyzed.In the laboratory frame,the spectator D meson in molecular state concentrates in the low momentum area.The energy from the transition from D^(*)to D meson is mainly acquired by two scattered D mesons.The results suggest that the D meson environment will lead to the induced fission-like process and chain reaction of the X(3827).Such a phenomenon can be extended to other hadronic molecular states.

第四纪:它的地位、时限、定义和存在的必要性

作为年代地层单位的术语,'第四纪'长期以来一直存在着争议,从最近发表的一些论文[1,2]以及论文所附的文献把这一争议推向极点.尽管过去对这一术语存在不确定性,但不能否认在对地球历史的研究中,大部分人是认同这一术语的.目前,争议已经不再集中在术语'第四纪'是否应该在地质年代表中占有一个位置,而争论的焦点在于给'第四纪'以合适的时间范围,以及相对于其他的地质年代单位,给予第四纪一个确切的定义.现已有好几个方案被提出来[1,2],Gibbard等[2]倡导在最后的决定作出之前,对这些方案进行深入讨论.在这一篇短文中,我们提出了一个前人尚未提出过的方案,我们认为这对问题的最后解决是有利的.首先,我们回顾一下将第四纪放在地质年代表和作为一个地质年代单位的两个地质时期,即更新世和新近纪的直接影响.

Effects of Globalisation on Developing Countries

Globalisation makes a significant difference to emergent nations.This paper provides insight into the benefits of globalisation on countries which have not been industrialised in respect to economy growth and well-being of population.Meanwhile,counter-arguments have been used to test the rigour of the paper.Whilst globalisation has brought a wider income gap and various new diseases,it has at the same time resulted in more positive than negative effects for countries with undeveloped industries.

Largely Deformed Dinuclear System Formed in ^19F ＋^27Al Dissipative Collision

Excitation functions are measured for different charge products of the ^19F＋^27AI reaction in the laboratory energy range 110.25-118.75MeV in steps of 250keV at θlab=57°,31° and -29°. The coherence rotation angular velocities of the intermediate dinuclear systems formed in the reaction are extracted from the cross section energy autocorrelation functions. Compared the angular velocity extracted from the experimental data with the ones deduced from the sticking limit, it is indicated that a larger deformation of the intermediate dinuclear system exists.

Exotic Behaviour of Angular Dispersion of Weakly Bound Nucleus ^17F at Small Angles

The differential cross sections of ^17F and ^17O elastic scattering products on ^208Pb have been measured at the Radioactive Ion Beam Line at Lanzhou （RIBLL）. Two angular dispersion plots of In（ dσ/ dθ ） versus 02 are obtained from the angular distribution of the elastic scattering differential cross sections. The angular dispersion plot exhibits a clear turning point for ^17F in the range of small scattering angles 6°-2° due to its exotic structure, but for ^17O, the turning point is not observed in the same angular range. The experimental results have been compared with previous data of other groups. Systematical analysis on the available data supports the above conclusion that there is an exotic behaviour of the angular dispersion plot of weakly bound nuclei with halo or skin structure as compared with that of the ordinary nuclei near stable line. Therefore the turning point of the angular dispersion plot appears at small angle for weakly bound nuclei with halo or skin structure, and can be used as a new probe to investigate the halo and skin phenomena of weakly bound nuclei.

Variable retention harvesting in Victoria’s Mountain Ash (Eucalyptus regnans) forests (southeastern Australia)

Variable retention harvesting is a silvicultural system that focuses on retaining key elements of stand structure at the time of logging and is increasingly being used worldwide.We describe the design and establishment of a variable retention harvesting experiment established in the Mountain Ash(Eucalyptus regnans)forests of the Central Highlands of Victoria,south-eastern Australia.The experiment was instigated in 2003,and the work to date has shown that it has environmental benefits for certain groups of small mammals,birds,and vascular plants.The experiment has been integrated with an ongoing long-term monitoring program as well as other experiments such as those in post-fire salvage-logged areas.Collectively,the results of various studies suggest that the potential value of variable retention harvesting extends beyond green-tree logging to post-fire salvage logging environments.We outline some of the challenges in,and new perspectives derived from,implementing and maintaining our experiment.This included difficulties protecting islands from high-intensity post-harvest regeneration burns and threat of declining funding undermining ongoing project viability.A critically important perspective concerns the ecological and economic context in which variable retention harvesting is implemented.In the particular case of Mountain Ash forests,assessments using formal IUCN criteria classify the ecosystem as being Critically Endangered under the Red Listed Ecosystem approach.As a result,Mountain Ash forests are at a high risk of ecosystem collapse.Further logging will increase that risk,making the basis for continued harvesting questionable.In addition,economic analyses suggest that the value of natural assets,like water production,far outweigh the value of the wood products harvested from the Mountain Ash ecosystem,again leading to questions about the viability of ongoing harvesting.We therefore conclude that whilst variable retention harvesting has the potential to contribute to biodiversity conservation in Mountain Ash forests,broader ecological and economic contextual issues(such as the values of competing resources like water yields and the heavily degraded state of the forest)may erode the case for its broader application.

Concentration-Dependent Solar Thermochemical CO_(2)/H_(2)O Splitting Performance by Vanadia-Ceria Multiphase Metal Oxide Systems

The effects of V and Ce concentrations(each varying in the 0-100%range)in vanadia-ceria multiphase systems are investigated for synthesis gas production via thermochemical redox cycles of CO_(2) and H_(2)O splitting coupled to methane partial oxidation reactions.The oxidation of prepared oxygen carriers is performed by separate and sequential CO_(2) and H_(2)O splitting reactions.Structural and chemical analyses of the mixed-metal oxides revealed important information about the Ce and V interactions affecting their crystal phases and redox characteristics.Pure CeO_(2) and pure V_(2)O_(5) are found to offer the lowest and highest oxygen exchange capacities and syngas production performance,respectively.The mixed-oxide systems provide a balanced performance:their oxygen exchange capacity is up to 5 times higher than that of pure CeO_(2) while decreasing the extent of methane cracking.The addition of 25%V to CeO_(2) results in an optimum mixture of CeO_(2) and CeVO4 for enhanced CO_(2) and H_(2)O splitting.At higher V concentrations,cyclic carbide formation and oxidation result in a syngas yield higher than that for pure CeO_(2).

Possible obliquity-forced warmth in southern Asia during the last glacial stage

Orbital-scale global climatic changes during the late Quaternary are dominated by high-latitude influenced~100,000-year global ice-age cycles and monsoon influenced~23,000-year low-latitude hydroclimate variations.However,the shortage of highly-resolved land temperature records remains a limiting factor for achieving a comprehensive understanding of long-term low-latitude terrestrial climatic changes.Here,we report paired mean annual air temperature(MAAT)and monsoon intensity proxy records over the past 88,000 years from Lake Tengchongqinghai in southwestern China.While summer monsoon intensity follows the~23,000-year precession beat found also in previous studies,we identify previously unrecognized warm periods at 88,000-71,000 and 45,000-22,000 years ago,with 2-3℃amplitudes that are close to our recorded full glacial-interglacial range.Using advanced transient climate simulations and comparing with forcing factors,we find that these warm periods in our MAAT record probably depends on local annual mean insolation,which is controlled by Earth’s~41,000-year obliquity cycles and is anti-phased to annual mean insolation at high latitudes.The coincidence of our identified warm periods and intervals of high-frequent dated archaeological evidence highlights the importance of temperature on anatomically modern humans in Asia during the last glacial stage.

The Role of Engineer-in-Chief and the Introduction of Foreign Hydraulic Dredging Technology and River Conservancy into China,1890s-1930s

This paper discusses studies of the development of river conservancy in modern China,and the role of engineers-in-chief in river improvement planning on rivers such as the Hai-ho(Haihe)and the Whangpoo(Huangpu).It discusses the introduction of foreign hydraulic dredging technology and management into two major Chinese ports.It then analyses the process by which two agencies of the Chinese government absorbed and adjusted this technology to suit local circumstances in the treaty ports of Tianjin and Shanghai beginning in the 1890s.Without prior experience in river conservancy,the conservancy boards adopted a range of foreign technologies.This allowed them to develop into major institutions that facilitated increasing trade flows between China and the rest of the world.Of particular significance in this process of technological change was the role of the expatriate engineers-in-chief who were employed as chief executive officers of both agencies.They were responsible for establishing the operations of the agencies,accommodating an increasing range of responsibilities such as financial and human resource management,and training Chinese engineers and managers for senior positions until they were ready to replace the expatriate engineers-in-chief after the 1930s.

A radical reinterpretation of the growth and form of the stromatolite Conophyton lituus(Maslov)from evidence of syngenetic biofilm mineralisation

Conophyton(Maslov)is a cylindroidal stromatolite form-genus characterized by nested conical laminae.Well-preserved Conophyton,up to 4 m tall and with basal diameters of up to 50 cm,are exposed in the Proterozoic Atar Formation of Mauritania,where many occur together,in growth position,as fields of individual columns spaced between 5 and 70 cm apart.The uniformity of these forms and their regular distribution suggest that they grew in quiet-water environments below wave base.Evidence for their penecontemporaneous organomineralization is indicated by nearby toppled examples of undeformed Conophyton forms alongside eroded lithified Conophyton fragments in carbonate breccias.Two characteristics of Conophyton have been used to classify the structures-the form of the lamination and the nature of its axial structure.A mathematical/physical model provides an explanation for the growth pattern of Conophyton.It predicts that coniform structures with thickened axial zones form when upward organic growth of a biofilm moderately exceeds the rate of its mineralization.The varying characteristics of these features between different forms of Conophyton are thought to reflect biomineralization of the decaying biofilm rather than differences in the composition of microbial communities.A modern example of a syngenetic mineralization process capable of producing similar structures has been observed in the contemporary sediments of Lake Preston,Western Australia,where benthic microbial mats are being transformed into coniform lithified crusts.The initial biomineralization of the coniform mat forms magnesium silicate that first coats and permineralizes web-like microbial extracellular polymeric substances(EPS)and then coalesces into a uniform mass that provides mechanical strength to the cones.At a later stage,massive carbonate crystal growth occurs that over-prints much of this texture,leaving only small,remnant areas of the magnesium silicate phase.Many fossil Conophyton are composed of dolomite,and the remains of the microbial communities responsible for their construction are rarely found,except in areas of chert within the Conophyton.It is suggested that Proterozoic Conophyton were constructed in a tranquil environment through the accretion of microbial mats that were syngenetically permineralized by a magnesium silicate such as a smectite.Later,much of the unstable smectite would be susceptible to diagenetic replacement by either dolomite,or chert in which remnants of microbes that had been coated or permineralized could,potentially,be preserved.