646 research outputs found

    Phytoplankton taxonomy, identification and enumeration

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    Phytoplankton are microscopic, free floating organisms and is the principal primary producers of the oceans. Their size range from 0.2 μm to 2 mm. Phytoplankton contains primary pigments and accessory pigments such as chlorophyll (Chl), carotenoids etc. which strongly absorbs the blue and red light of the visible spectra. Phytoplankton also influences the total scattering properties of sea water

    Direct mapping of the finite temperature phase diagram of strongly correlated quantum models

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    Optical lattice experiments, with the unique potential of tuning interactions and density, have emerged as emulators of nontrivial theoretical models that are directly relevant for strongly correlated materials. However, so far the finite temperature phase diagram has not been mapped out for any strongly correlated quantum model. We propose a remarkable method for obtaining such a phase diagram for the first time directly from experiments using only the density profile in the trap as the input. We illustrate the procedure explicitly for the Bose Hubbard model, a textbook example of a quantum phase transition from a superfluid to a Mott insulator. Using "exact" quantum Monte Carlo simulations in a trap with up to 10610^6 bosons, we show that kinks in the local compressibility, arising from critical fluctuations, demarcate the boundaries between superfluid and normal phases in the trap. The temperature of the bosons in the optical lattice is determined from the density profile at the edge. Our method can be applied to other phase transitions even when reliable numerical results are not available.Comment: 12 pages, 5 figure

    A subclass of bi-univalent functions related to shell-like curves connected with Fibonacci numbers associated with (p, q)-derivative

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    In this paper, we define a new subclass of bi-univalent functions related to shell-like curves connected with Fibonacci numbers by using (p, q)-derivative and the coefficient estimates, Fekete-Szego inequalities are discussed for the functions belonging to this class.Publisher's Versio

    Stroke Prediction from Hypertensive Retinopathy

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    Hypertensive Retinopathy (HR) is known as the damage to the eye which occurs due to high blood pressure. This HR may lead to permanent vision lost hence timely diagnosis and treatment of this disease is very important. Fundus image analysis is used to diagnose HR and stroke prediction. There are four steps in the proposed systems which are the Image Enhancement, Fourier Fractal Dimension, Logistic Regression Classifier and Stroke Prediction Model. The proposed system consists of method used to analyse retina blood vessels using Fourier Fractal Dimension to extract the complexity of the retina blood vessels enhanced in different scales. Logistic regression was used to model the classifier for stroke prediction. The probability from 0 to 0.5 was classified as control case and the probability from 0.5 to 1 was classified as stroke case. From 20 images used in this project only 14 images was classified as the stroke case. The estimated percentage increase in the odds of incident of stroke is calculated and categorised according to the Hypertensive Retinopathy stages

    Phytoplankton functional types

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    The term “functional types” emerged from biogeochemical studies. It represents the group of organisms that share common characteristic role in biogeochemical functions. In ecology, a functional type or group represents an aggregation of organisms according to some well-defined property that sets a role or “function” for them in a system. Phytoplankton Functional types (PFT) are defined as a group of organisms (irrespective of taxonomic affiliation) that carry out a particular chemical process such as calcification, silicification, nitrogen fixation, or dimethyl sulfide production; they are also referred to as “biogeochemical guilds”. For example, in Nitrogen-Phytoplankton-Zooplankton (NPZ) models, P and Z are representatives of functional types, i.e., producers and consumers. This aggregation is acceptable for some applications, but may be too coarse or even inappropriate for others

    Pairing and superconductivity driven by strong quasiparticle renormalization in two-dimensional organic charge transfer salts

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    We introduce and analyze a variational wave function for quasi two-dimensional kappa-ET organic salts containing strong local and nonlocal correlation effects. We find an unconventional superconducting ground state for intermediate charge carrier interaction, sandwiched between a conventional metal at weak coupling and a spin liquid at larger coupling. Most remarkably, the excitation spectrum is dramatically renormalized and is found to be the driving force for the formation of the unusual superconducting state.Comment: 4 pages, 4 figure

    Particle-Hole Asymmetry in Doped Mott Insulators: Implications for Tunneling and Photoemission Spectroscopies

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    In a system with strong local repulsive interactions it should be more difficult to add an electron than to extract one. We make this idea precise by deriving various exact sum rules for the one-particle spectral function independent of the details of the Hamiltonian describing the system and of the nature of the ground state. We extend these results using a variational ansatz for the superconducting ground state and low lying excitations. Our results shed light on the striking asymmetry in the tunneling spectra of high Tc superconductors and should also be useful in estimating the local doping variations in inhomogeneous materials.Comment: 4 pages, no figure

    Fermions in 3D Optical Lattices: Cooling Protocol to Obtain Antiferromagnetism

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    A major challenge in realizing antiferromagnetic (AF) and superfluid phases in optical lattices is the ability to cool fermions. We determine the equation of state for the 3D repulsive Fermi-Hubbard model as a function of the chemical potential, temperature and repulsion using unbiased determinantal quantum Monte Carlo methods, and we then use the local density approximation to model a harmonic trap. We show that increasing repulsion leads to cooling, but only in a trap, due to the redistribution of entropy from the center to the metallic wings. Thus, even when the average entropy per particle is larger than that required for antiferromagnetism in the homogeneous system, the trap enables the formation of an AF Mott phase.Comment: 4 pages; 5 figures; also see supplementary material in 2 pages with 1 figur
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