Ripple modulated electronic structure of a 3D topological insulator

3D topological insulators, similar to the Dirac material graphene, host linearly dispersing states with unique properties and a strong potential for applications. A key, missing element in realizing some of the more exotic states in topological insulators is the ability to manipulate local electronic properties. Analogy with graphene suggests a possible avenue via a topographic route by the formation of superlattice structures such as a moir\'e patterns or ripples, which can induce controlled potential variations. However, while the charge and lattice degrees of freedom are intimately coupled in graphene, it is not clear a priori how a physical buckling or ripples might influence the electronic structure of topological insulators. Here we use Fourier transform scanning tunneling spectroscopy to determine the effects of a one-dimensional periodic buckling on the electronic properties of Bi2Te3. By tracking the spatial variations of the scattering vector of the interference patterns as well as features associated with bulk density of states, we show that the buckling creates a periodic potential modulation, which in turn modulates the surface and the bulk states. The strong correlation between the topographic ripples and electronic structure indicates that while doping alone is insufficient to create predetermined potential landscapes, creating ripples provides a path to controlling the potential seen by the Dirac electrons on a local scale. Such rippled features may be engineered by strain in thin films and may find use in future applications of topological insulators.Comment: Nature Communications (accepted

Fractional quantum Hall effect in the absence of Landau levels

It has been well-known that topological phenomena with fractional excitations, i.e., the fractional quantum Hall effect (FQHE) \cite{Tsui1982} will emerge when electrons move in Landau levels. In this letter, we report the discovery of the FQHE in the absence of Landau levels in an interacting fermion model. The non-interacting part of our Hamiltonian is the recently proposed topologically nontrivial flat band model on the checkerboard lattice \cite{sun}. In the presence of nearest-neighboring repulsion ($U$), we find that at 1/3 filling, the Fermi-liquid state is unstable towards FQHE. At 1/5 filling, however, a next-nearest-neighboring repulsion is needed for the occurrence of the 1/5 FQHE when $U$ is not too strong. We demonstrate the characteristic features of these novel states and determine the phase diagram correspondingly.Comment: 6 pages and 4 figure

Development of Photonic Crystal Fiber Based Gas/ Chemical Sensors

The development of highly-sensitive and miniaturized sensors that capable of real-time analytes detection is highly desirable. Nowadays, toxic or colorless gas detection, air pollution monitoring, harmful chemical, pressure, strain, humidity, and temperature sensors based on photonic crystal fiber (PCF) are increasing rapidly due to its compact structure, fast response and efficient light controlling capabilities. The propagating light through the PCF can be controlled by varying the structural parameters and core-cladding materials, as a result, evanescent field can be enhanced significantly which is the main component of the PCF based gas/chemical sensors. The aim of this chapter is to (1) describe the principle operation of PCF based gas/ chemical sensors, (2) discuss the important PCF properties for optical sensors, (3) extensively discuss the different types of microstructured optical fiber based gas/ chemical sensors, (4) study the effects of different core-cladding shapes, and fiber background materials on sensing performance, and (5) highlight the main challenges of PCF based gas/ chemical sensors and possible solutions

Rice marketing system, profitability and middlemen’s role in two districts of Bangladesh

The study attempts to identify the rice marketing channels, market actors and their marketing functions in Bogura and Gaibandha districts in Bangladesh. The paper also examines the rice marketing cost and margin and highlight major obstacles of market actors. Primary data were collected from 25 middlemen by using pretested semi-structured interview schedule in 2017. Rice millers, wholesalers and retailers were the major market’s actors in the study areas. Most of the rice millers buy paddy directly from the farmers by using their agent. After processing rice, rice millers sell rice to the wholesalers, and retailers. Rice millers marketing costs were higher in the Bogura district (Tk.569.8/40kg) than Gaibandha district (Tk.526.0/40kg). However, retailers’ marketing costs were higher in Gaibandha district (Tk.43.0/40kg) than Bogura district (Tk.39.1/40kg). Among all intermediaries, marketing margins was highest for rice millers which were Tk. 227.5/40kg. Middlemen have no sufficient capital for investment. Therefore, Government, Non Government Organizations and other institutional credit should be available to them at the reasonable interest rate

URBAN CULTURE AND PRIORITY VILLAGE PROGRAMS IN A GLOBAL CONTEXT: CASE STUDY OF KAMPUNG SUSUN BAHARI AKUARIUM

Settlement arrangement in Jakarta is refer to the concept of global development context began in the 1900s with the Menteng and New Gondangdia projects at the first. After independence, the expansion of residential land extended to Kebayoran and Tebet, resulting a lesser land for housing development. The existence of kampungs in Jakarta is increasingly shifted by the development of housing complexes. And the impact of increasing urbanization has led to the development of slum areas in Jakarta, thereby putting pressure on the government to provide vertical population services. The DKI Jakarta government then compiled a development strategy to remove slum area in 445 RWs recorded in 2017 through the Priority Kampung development program, one of which was the construction of the Kampung Susun Bahari Akuarium (KSBA) in Penjaringan, North Jakarta. This theme study is a development of an existing study and examines two aspects, namely the aspect of social change in society in terms of urban village culture and changes in occupancy from horizontal housing to vertical housing for people in urban areas with a tropical tropical atmosphere. This study uses a multidisciplinary historical approach by tracing colonial period map documents, mass media news, government policies and past literature searches

Rice marketing system, profitability and middlemen’s role in two districts of Bangladesh

The study attempts to identify the rice marketing channels, market actors and their marketing functions in Bogura and Gaibandha districts in Bangladesh. The paper also examines the rice marketing cost and margin and highlight major obstacles of market actors. Primary data were collected from 25 middlemen by using pretested semi-structured interview schedule in 2017. Rice millers, wholesalers and retailers were the major market’s actors in the study areas. Most of the rice millers buy paddy directly from the farmers by using their agent. After processing rice, rice millers sell rice to the wholesalers, and retailers. Rice millers marketing costs were higher in the Bogura district (Tk.569.8/40kg) than Gaibandha district (Tk.526.0/40kg). However, retailers’ marketing costs were higher in Gaibandha district (Tk.43.0/40kg) than Bogura district (Tk.39.1/40kg). Among all intermediaries, marketing margins was highest for rice millers which were Tk. 227.5/40kg. Middlemen have no sufficient capital for investment. Therefore, Government, Non Government Organizations and other institutional credit should be available to them at the reasonable interest rate

Turbulence and galactic structure

Interstellar turbulence is driven over a wide range of scales by processes including spiral arm instabilities and supernovae, and it affects the rate and morphology of star formation, energy dissipation, and angular momentum transfer in galaxy disks. Star formation is initiated on large scales by gravitational instabilities which control the overall rate through the long dynamical time corresponding to the average ISM density. Stars form at much higher densities than average, however, and at much faster rates locally, so the slow average rate arises because the fraction of the gas mass that forms stars at any one time is low, ~10^{-4}. This low fraction is determined by turbulence compression, and is apparently independent of specific cloud formation processes which all operate at lower densities. Turbulence compression also accounts for the formation of most stars in clusters, along with the cluster mass spectrum, and it gives a hierarchical distribution to the positions of these clusters and to star-forming regions in general. Turbulent motions appear to be very fast in irregular galaxies at high redshift, possibly having speeds equal to several tenths of the rotation speed in view of the morphology of chain galaxies and their face-on counterparts. The origin of this turbulence is not evident, but some of it could come from accretion onto the disk. Such high turbulence could help drive an early epoch of gas inflow through viscous torques in galaxies where spiral arms and bars are weak. Such evolution may lead to bulge or bar formation, or to bar re-formation if a previous bar dissolved. We show evidence that the bar fraction is about constant with redshift out to z~1, and model the formation and destruction rates of bars required to achieve this constancy.Comment: in: Penetrating Bars through Masks of Cosmic Dust: The Hubble Tuning Fork strikes a New Note, Eds., K. Freeman, D. Block, I. Puerari, R. Groess, Dordrecht: Kluwer, in press (presented at a conference in South Africa, June 7-12, 2004). 19 pgs, 5 figure

Entomological Surveillance of Behavioural Resilience and Resistance in Residual Malaria Vector Populations.

The most potent malaria vectors rely heavily upon human blood so they are vulnerable to attack with insecticide-treated nets (ITNs) and indoor residual spraying (IRS) within houses. Mosquito taxa that can avoid feeding or resting indoors, or by obtaining blood from animals, mediate a growing proportion of the dwindling transmission that persists as ITNs and IRS are scaled up. Increasing frequency of behavioural evasion traits within persisting residual vector systems usually reflect the successful suppression of the most potent and vulnerable vector taxa by IRS or ITNs, rather than their failure. Many of the commonly observed changes in mosquito behavioural patterns following intervention scale-up may well be explained by modified taxonomic composition and expression of phenotypically plastic behavioural preferences, rather than altered innate preferences of individuals or populations. Detailed review of the contemporary evidence base does not yet provide any clear-cut example of true behavioural resistance and is, therefore, consistent with the hypothesis presented. Caution should be exercised before over-interpreting most existing reports of increased frequency of behavioural traits which enable mosquitoes to evade fatal contact with insecticides: this may simply be the result of suppressing the most behaviourally vulnerable of the vector taxa that constituted the original transmission system. Mosquito taxa which have always exhibited such evasive traits may be more accurately described as behaviourally resilient, rather than resistant. Ongoing national or regional entomological monitoring surveys of physiological susceptibility to insecticides should be supplemented with biologically and epidemiologically meaningfully estimates of malaria vector population dynamics and the behavioural phenotypes that determine intervention impact, in order to design, select, evaluate and optimize the implementation of vector control measures

An Introductory Guide to Aligning Networks Using SANA, the Simulated Annealing Network Aligner.

Sequence alignment has had an enormous impact on our understanding of biology, evolution, and disease. The alignment of biological networks holds similar promise. Biological networks generally model interactions between biomolecules such as proteins, genes, metabolites, or mRNAs. There is strong evidence that the network topology-the "structure" of the network-is correlated with the functions performed, so that network topology can be used to help predict or understand function. However, unlike sequence comparison and alignment-which is an essentially solved problem-network comparison and alignment is an NP-complete problem for which heuristic algorithms must be used.Here we introduce SANA, the Simulated Annealing Network Aligner. SANA is one of many algorithms proposed for the arena of biological network alignment. In the context of global network alignment, SANA stands out for its speed, memory efficiency, ease-of-use, and flexibility in the arena of producing alignments between two or more networks. SANA produces better alignments in minutes on a laptop than most other algorithms can produce in hours or days of CPU time on large server-class machines. We walk the user through how to use SANA for several types of biomolecular networks