1,014 research outputs found
A Preliminary assessment of the efficacy of a Chlorine Bleach Detection Method for use in Spiny Lobster (Panulirus argus) fisheries
MaxEnt and dynamical information
The MaxEnt solutions are shown to display a variety of behaviors (beyond the
traditional and customary exponential one) if adequate dynamical information is
inserted into the concomitant entropic-variational principle. In particular, we
show both theoretically and numerically that power laws and power laws with
exponential cut-offs emerge as equilibrium densities in proportional and other
dynamics
The structure of flame filaments in chaotic flows
The structure of flame filaments resulting from chaotic mixing within a
combustion reaction is considered. The transverse profile of the filaments is
investigated numerically and analytically based on a one-dimensional model that
represents the effect of stirring as a convergent flow. The dependence of the
steady solutions on the Damkohler number and Lewis number is treated in detail.
It is found that, below a critical Damkohler number Da(crit), the flame is
quenched by the flow. The quenching transition appears as a result of a
saddle-node bifurcation where the stable steady filament solution collides with
an unstable one. The shape of the steady solutions for the concentration and
temperature profiles changes with the Lewis number and the value of Da(crit)
increases monotonically with the Lewis number. Properties of the solutions are
studied analytically in the limit of large Damkohler number and for small and
large Lewis number.Comment: 17 pages, 13 figures, to be published in Physica
Fabrication of an autonomously self-healing flexible thin-film capacitor by slot-die coating
Flexible pressure sensors with self-healing abilities for wearable electronics are being developed, but generally either lack autonomous self-healing properties or require sophisticated material processing methods. To address this challenge, we developed flexible, low-cost and autonomously self-healing capacitive sensors using a crosslinked poly(dimethylsiloxane) through metal-ligand interactions processed into thin films via slot-die coating. These films have excellent self-healing properties, approximately 1.34 × 105 μm3 per hour at room temperature and 2.87 × 105 μm3 per hour at body temperature (37 °C). Similarly, no significant change in capacitance under bending strain was observed on these flexible thin-films when assembled on poly(ethyleneterephthalate) (PET) substrates; capacitors showed good sensitivity at low pressure regimes. More importantly, the devices fully recovered their sensitivity after being damaged and healed, which is directly attributed to the rapid and autonomous self-healing of the dielectric materials
On the Interpretation of Energy as the Rate of Quantum Computation
Over the last few decades, developments in the physical limits of computing
and quantum computing have increasingly taught us that it can be helpful to
think about physics itself in computational terms. For example, work over the
last decade has shown that the energy of a quantum system limits the rate at
which it can perform significant computational operations, and suggests that we
might validly interpret energy as in fact being the speed at which a physical
system is "computing," in some appropriate sense of the word. In this paper, we
explore the precise nature of this connection. Elementary results in quantum
theory show that the Hamiltonian energy of any quantum system corresponds
exactly to the angular velocity of state-vector rotation (defined in a certain
natural way) in Hilbert space, and also to the rate at which the state-vector's
components (in any basis) sweep out area in the complex plane. The total angle
traversed (or area swept out) corresponds to the action of the Hamiltonian
operator along the trajectory, and we can also consider it to be a measure of
the "amount of computational effort exerted" by the system, or effort for
short. For any specific quantum or classical computational operation, we can
(at least in principle) calculate its difficulty, defined as the minimum effort
required to perform that operation on a worst-case input state, and this in
turn determines the minimum time required for quantum systems to carry out that
operation on worst-case input states of a given energy. As examples, we
calculate the difficulty of some basic 1-bit and n-bit quantum and classical
operations in an simple unconstrained scenario.Comment: Revised to address reviewer comments. Corrects an error relating to
time-ordering, adds some additional references and discussion, shortened in a
few places. Figures now incorporated into tex
Use of non-adiabatic geometric phase for quantum computing by nuclear magnetic resonance
Geometric phases have stimulated researchers for its potential applications
in many areas of science. One of them is fault-tolerant quantum computation. A
preliminary requisite of quantum computation is the implementation of
controlled logic gates by controlled dynamics of qubits. In controlled
dynamics, one qubit undergoes coherent evolution and acquires appropriate
phase, depending on the state of other qubits. If the evolution is geometric,
then the phase acquired depend only on the geometry of the path executed, and
is robust against certain types of errors. This phenomenon leads to an
inherently fault-tolerant quantum computation.
Here we suggest a technique of using non-adiabatic geometric phase for
quantum computation, using selective excitation. In a two-qubit system, we
selectively evolve a suitable subsystem where the control qubit is in state
|1>, through a closed circuit. By this evolution, the target qubit gains a
phase controlled by the state of the control qubit. Using these geometric phase
gates we demonstrate implementation of Deutsch-Jozsa algorithm and Grover's
search algorithm in a two-qubit system
Moduli Webs and Superpotentials for Five-Branes
We investigate the one-parameter Calabi-Yau models and identify families of
D5-branes which are associated to lines embedded in these manifolds. The moduli
spaces are given by sets of Riemann curves, which form a web whose intersection
points are described by permutation branes. We arrive at a geometric
interpretation for bulk-boundary correlators as holomorphic differentials on
the moduli space and use this to compute effective open-closed superpotentials
to all orders in the open string couplings. The fixed points of D5-brane moduli
under bulk deformations are determined.Comment: 41 pages, 1 figur
Morse theory of the moment map for representations of quivers
The results of this paper concern the Morse theory of the norm-square of the
moment map on the space of representations of a quiver. We show that the
gradient flow of this function converges, and that the Morse stratification
induced by the gradient flow co-incides with the Harder-Narasimhan
stratification from algebraic geometry. Moreover, the limit of the gradient
flow is isomorphic to the graded object of the
Harder-Narasimhan-Jordan-H\"older filtration associated to the initial
conditions for the flow. With a view towards applications to Nakajima quiver
varieties we construct explicit local co-ordinates around the Morse strata and
(under a technical hypothesis on the stability parameter) describe the negative
normal space to the critical sets. Finally, we observe that the usual Kirwan
surjectivity theorems in rational cohomology and integral K-theory carry over
to this non-compact setting, and that these theorems generalize to certain
equivariant contexts.Comment: 48 pages, small revisions from previous version based on referee's
comments. To appear in Geometriae Dedicat
On non-local variational problems with lack of compactness related to non-linear optics
We give a simple proof of existence of solutions of the dispersion manage-
ment and diffraction management equations for zero average dispersion,
respectively diffraction. These solutions are found as maximizers of non-linear
and non-local vari- ational problems which are invariant under a large
non-compact group. Our proof of existence of maximizer is rather direct and
avoids the use of Lions' concentration compactness argument or Ekeland's
variational principle.Comment: 30 page
Population growth and reproductive potential of five important fishes from the freshwater bodies of Bangladesh
Population growth (length-weight relationship), and reproductive potential (e.g. fecundity, and sex-ratio) of five important fish species (‘mola’: Amblypharyngodon mola, ‘puti’: Puntius sophore, ‘tengra’: Mystus vittatus, ‘shing’: Heteropneustes fossilis and ‘taki’: Channa punctatus) collected from two important fresh water bodies (namely Hilna beel and Beel Kumari beel) Rajshahi, Bangladesh, were studied. Population growth pattern by length-weight relationship (W=aLb ) for the species differed, and exhibited positive allometric growth (P. sophore in Hilna beel), isometric growth (A. mola and C. punctatus in Hilna beel) and negative allometric growth (M. vittatus & H. fossilis in Hilna beel and A. mola, P. sophore, M. vittatus, C. punctatus and H. fossilis in Beel Kumari beel). The results denoted that fecundity of mature females followed a non-linear relationship (F=aLb ) with total length and exhibited positive allometric growth (b>3) with some exception (A. mola in Hilna beel and M. vittatus in Beel Kumari beel). Fecundity of mature females also increased with total body weight and ovary weight following a linear relationship (F=a+bW). Differences in values of sexratios with seasons for all species in this study may have resulted from different environmental factors as well as breeding seasons. The findings of this study would be useful in imposing adequate regulations for the conservation of these fascinating fishes in the fresh water bodies of Bangladesh
- …