452 research outputs found
A report on the occurrence of Bangana dero (Hamilton, 1822) from Deepor beel (Ramsar site no. 1207), Brahmaputra valley, Assam
Deepor beel (Latitude: 26°05?26??N to 26°09?26?? N; Longitude: 90°36' E to 90°41?25?? E) located in Kamrup district, Assam is a large (water spread area of 589 ha) natural wetland and a Ramsar site of international importance (Site number 1207 declared in 2002) having enormous biological and environmental importance. The wetland receives water from surface run-off as well as from two hill streams (Basistha and Kalamoni) and drains into River Brahmaputra, through a small rivulet (Khanajan). The beel supports a number of endemic endangered and threatened animals and plants that are included under IUCN red-list. Past studies indicated the occurrence of 67 fin-fish species in the beel. In a recent survey conducted by us, the beel Bangana dero (Synonyms: Cyprinus dero/ Labeo dero), a cyprinid fish, was collected for the first time from the beel. We collected as many as 28 specimens of B. dero from the beel during October 2016. The total length of the reported specimens ranged from 8.77 - 10.14 cm and weight ranged from 6.74 - 10.61 g. The length-weight relationship of the species was worked out as W = 0.074*L2.103. B. dero reportedly inhabits upland rivers, torrential hill-streams; adults migrate to warm downstream regions during the winter season (December-February). Thus, the occurrence of this species in Deepor beel indicates its possible downstream migration from one or both the feeder rivers (Basistha and Kalamoni) or migration from Brahmaputra River through its connecting channel. 
Temperature dependence of the effective spin-mixing conductance probed with lateral non-local spin valves
We report the temperature dependence of the effective spin-mixing conductance
between a normal metal (aluminium, Al) and a magnetic insulator
(, YIG). Non-local spin valve devices,
using Al as the spin transport channel, were fabricated on top of YIG and
SiO substrates. By comparing the spin relaxation lengths in the Al channel
on the two different substrates, we calculate the effective spin-mixing
conductance () to be ~
at 293~K for the Al/YIG interface. A decrease of up to 84\% in is
observed when the temperature () is decreased from 293~K to 4.2~K, with
scaling with . The real part of the
spin-mixing conductance (), calculated from the experimentally obtained
, is found to be approximately independent of the temperature. We
evidence a hitherto unrecognized underestimation of extracted from
the modulation of the spin signal by rotating the magnetization direction of
YIG with respect to the spin accumulation direction in the Al channel, which is
found to be 50 times smaller than the calculated value
Improvement of the economic and operational efficiency of freight road and rail transportation in south africa
In South Africa, freight transport movement is largely provided by parastatals in railways,
ports, pipelines, and aviation. However, freight transportation suffers from the challenges
and limitations such as adverse environmental impact, congestion, overloading and high
freight costs. Therefore, the objective of this study was to explore how to improve the
economic and operational efficiency of freight road and rail transportation by implementing
the new freight transportation system. In other words, how both transportation modes can
be used effectively to enable lesser travel times, low freight load costs and fast delivery of
diverse commodities in South Africa. The methodology adopted in this study was through
the collection of data by survey questionnaires among various stakeholders involved in the
freight industry which later underwent comparative analysis. The findings reveal that
freight road is much more competitive than freight rail as it can provide fast travel times,
carry less freight loads, and accommodate various commodities. Furthermore, based on
the current study, a domestic intermodal freight transportation is recommended for an
improved economic and operational efficiency of freight road and rail by consideration of
aspects such as freight costs, travel factors and economic contribution; thereby allowing
freight rail to be utilized on long haul distances and road for short distances.Papers presented at the 40th International Southern African Transport Conference on 04 -08 July 202
Temperature dependence of the effective spin-mixing conductance probed with lateral non-local spin valves
We report the temperature dependence of the effective spin-mixing conductance between a normal metal (aluminium, Al) and a magnetic insulator (Y3Fe5O12, YIG). Non-local spin valve devices, using Al as the spin transport channel, were fabricated on top of YIG and SiO2 substrates. By comparing the spin relaxation lengths in the Al channel on the two different substrates, we calculate the effective spin-mixing conductance (Gs) to be 3.3 × 1012 Ω−1m−2 at 293 K for the Al/YIG interface. A decrease of up to 84% in Gs is observed when the temperature (T) is decreased from 293 K to 4.2 K, with Gs scaling with (T /Tc)3/2. The real part of the spin-mixing conductance (Gr ≈ 5.7 × 1013 Ω−1m−2), calculated from the experimentally obtained Gs, is found to be approximately independent of the temperature. We evidence a hitherto unrecognized underestimation of Gr extracted from the modulation of the spin signal by rotating the magnetization direction of YIG with respect to the spin accumulation direction in the Al channel, which is found to be 50 times smaller than the calculated value
Topological order in 1D Cluster state protected by symmetry
We demonstrate how to construct the Z2*Z2 global symmetry which protects the
ground state degeneracy of cluster states for open boundary conditions. Such a
degeneracy ultimately arises because the set of stabilizers do not span a
complete set of integrals of motion of the cluster state Hamiltonian for open
boundary conditions. By applying control phase transformations, our
construction makes the stabilizers into the Pauli operators spanning the qubit
Hilbert space from which the degeneracy comes.Comment: 1 figure, To be published in Quantum Information Processin
Phase Transitions of Hard Disks in External Periodic Potentials: A Monte Carlo Study
The nature of freezing and melting transitions for a system of hard disks in
a spatially periodic external potential is studied using extensive Monte Carlo
simulations. Detailed finite size scaling analysis of various thermodynamic
quantities like the order parameter, its cumulants etc. are used to map the
phase diagram of the system for various values of the density and the amplitude
of the external potential. We find clear indication of a re-entrant liquid
phase over a significant region of the parameter space. Our simulations
therefore show that the system of hard disks behaves in a fashion similar to
charge stabilized colloids which are known to undergo an initial freezing,
followed by a re-melting transition as the amplitude of the imposed, modulating
field produced by crossed laser beams is steadily increased. Detailed analysis
of our data shows several features consistent with a recent dislocation
unbinding theory of laser induced melting.Comment: 36 pages, 16 figure
Integrability and Conformal Symmetry in the BCS model
The exactly solvable BCS Hamiltonian of superconductivity is considered from
several viewpoints: Richardson's ansatz, conformal field theory, integrable
inhomogenous vertex models and Chern-Simons theory.Comment: Latex with macros included, 12 pages, Proceedings of the NATO
Advanced Research Workshop on Statistical Field Theories, Como 18-23 June
2001. Editors: Andrea Cappelli and Giuseppe Mussardo. to be published by
Kluwer, Academic Publishers. Corrected some typos and further acknowledgment
Quantum critical point and scaling in a layered array of ultrasmall Josephson junctions
We have studied a quantum Hamiltonian that models an array of ultrasmall
Josephson junctions with short range Josephson couplings, , and charging
energies, , due to the small capacitance of the junctions. We derive a new
effective quantum spherical model for the array Hamiltonian. As an application
we start by approximating the capacitance matrix by its self-capacitive limit
and in the presence of an external uniform background of charges, . In
this limit we obtain the zero-temperature superconductor-insulator phase
diagram, , that improves upon previous theoretical
results that used a mean field theory approximation. Next we obtain a
closed-form expression for the conductivity of a square array, and derive a
universal scaling relation valid about the zero--temperature quantum critical
point. In the latter regime the energy scale is determined by temperature and
we establish universal scaling forms for the frequency dependence of the
conductivity.Comment: 18 pages, four Postscript figures, REVTEX style, Physical Review B
1999. We have added one important reference to this version of the pape
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