646 research outputs found
Phytoplankton taxonomy, identification and enumeration
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
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 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
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
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
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
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
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
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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