74 research outputs found
AI pipeline for accurate retinal layer segmentation using OCT 3D images
Image data set from a multi-spectral animal imaging system is used to address
two issues: (a) registering the oscillation in optical coherence tomography
(OCT) images due to mouse eye movement and (b) suppressing the shadow region
under the thick vessels/structures. Several classical and AI-based algorithms
in combination are tested for each task to see their compatibility with data
from the combined animal imaging system. Hybridization of AI with optical flow
followed by Homography transformation is shown to be working (correlation
value>0.7) for registration. Resnet50 backbone is shown to be working better
than the famous U-net model for shadow region detection with a loss value of
0.9. A simple-to-implement analytical equation is shown to be working for
brightness manipulation with a 1% increment in mean pixel values and a 77%
decrease in the number of zeros. The proposed equation allows formulating a
constraint optimization problem using a controlling factor {\alpha} for
minimization of number of zeros, standard deviation of pixel value and
maximizing the mean pixel value. For Layer segmentation, the standard U-net
model is used. The AI-Pipeline consists of CNN, Optical flow, RCNN, pixel
manipulation model, and U-net models in sequence. The thickness estimation
process has a 6% error as compared to manual annotated standard data.Comment: 16 Page and 11 Figure
Relative estimation of scattering noise and its utility to select radiation detector for Gamma CT scanner
This study investigates two unavoidable noise factors: electronic noise and
radiation scattering, associated with detectors and their electronics. This
study proposes a novel methodology to estimate electronic and scattering noise
separately. It utilizes mathematical tools, namely, Kanpur theorem-1, standard
deviation, similarity dice coefficient parameters, and experimental
Computerized Tomography technique. Four types of gamma detectors: CsI (Tl),
LaBr_3 (Ce), NaI (Tl) and HPGe are used with their respective electronics. A
detector having integrated circuit electronics is shown to impart significantly
less (~33% less) electronic noise in data as compared to detectors with
distributed electronics. Kanpur Theorem-1 signature is proposed as a scattering
error estimate. An empirical expression is developed showing that scattering
noise depends strongly on mass attenuation coefficients of detector crystal
material and weakly on their active area. The difference between predicted and
estimated relative scattering is 14.6%. The methodology presented in this study
will assist the related industry in selecting the appropriate detector of
optimal diameter, thickness, material composition, and hardware as per
requirement.Comment: 9 Figures and 15 Page
Universal Sorting: Finding a DAG using Priced Comparisons
We resolve two open problems in sorting with priced information, introduced
by [Charikar, Fagin, Guruswami, Kleinberg, Raghavan, Sahai (CFGKRS), STOC
2000]. In this setting, different comparisons have different (potentially
infinite) costs. The goal is to sort with small competitive ratio (algorithmic
cost divided by cheapest proof).
1) When all costs are in , we give an algorithm that has
competitive ratio. Our algorithm generalizes the
algorithms for generalized sorting (all costs are either or ), a
version initiated by [Huang, Kannan, Khanna, FOCS 2011] and addressed recently
by [Kuszmaul, Narayanan, FOCS 2021].
2) We answer the problem of bichromatic sorting posed by [CFGKRS]: The input
is split into and , and and comparisons are more expensive
than an comparisons. We give a randomized algorithm with a O(polylog n)
competitive ratio.
These results are obtained by introducing the universal sorting problem,
which generalizes the existing framework in two important ways. We remove the
promise of a directed Hamiltonian path in the DAG of all comparisons. Instead,
we require that an algorithm outputs the transitive reduction of the DAG. For
bichromatic sorting, when and comparisons cost , this
generalizes the well-known nuts and bolts problem. We initiate an
instance-based study of the universal sorting problem. Our definition of
instance-optimality is inherently more algorithmic than that of the competitive
ratio in that we compare the cost of a candidate algorithm to the cost of the
optimal instance-aware algorithm. This unifies existing lower bounds, and opens
up the possibility of an -instance optimal algorithm for the bichromatic
version.Comment: 40 pages, 5 figure
Awareness of Farmers about the Primary Agriculture Credit Societies (With Special Reference of Uttar Pradesh and Uttarakhand)
Primary Agriculture Credit Society is a basic unit and smallest cooperative credit institution in India. It works on the grass-root level (gram panchayat and village level). Primary Agriculture Credit Society is formed at the village or town level. It is the old cooperative credit system of India. Primary Agriculture Credit Society was designed to be a village-level credit society into which the farmers brought in share capital, deposits, and provide loans to each other. This study aims to assess the Awareness of Farmers about the Primary Agricultural Credit Societies with Special Reference to Uttar Pradesh and Uttarakhand. 58% of farmers know about primary agriculture credit societies and this study will useful for the rural areas policymakers and this study will also useful for many other stakeholders
An Algorithm for Bichromatic Sorting with Polylog Competitive Ratio
The problem of sorting with priced information was introduced by [Charikar,
Fagin, Guruswami, Kleinberg, Raghavan, Sahai (CFGKRS), STOC 2000]. In this
setting, different comparisons have different (potentially infinite) costs. The
goal is to find a sorting algorithm with small competitive ratio, defined as
the (worst-case) ratio of the algorithm's cost to the cost of the cheapest
proof of the sorted order.
The simple case of bichromatic sorting posed by [CFGKRS] remains open: We are
given two sets and of total size , and the cost of an
comparison or a comparison is higher than an comparison. The goal
is to sort . An lower bound on competitive ratio
follows from unit-cost sorting. Note that this is a generalization of the
famous nuts and bolts problem, where and comparisons have infinite
cost, and elements of and are guaranteed to alternate in the final
sorted order.
In this paper we give a randomized algorithm InversionSort with an
almost-optimal w.h.p. competitive ratio of . This is the first
algorithm for bichromatic sorting with a competitive ratio.Comment: 18 pages, accepted to ITCS 2024. arXiv admin note: text overlap with
arXiv:2211.0460
Computing Teichm\"{u}ller Maps between Polygons
By the Riemann-mapping theorem, one can bijectively map the interior of an
-gon to that of another -gon conformally. However, (the boundary
extension of) this mapping need not necessarily map the vertices of to
those . In this case, one wants to find the ``best" mapping between these
polygons, i.e., one that minimizes the maximum angle distortion (the
dilatation) over \textit{all} points in . From complex analysis such maps
are known to exist and are unique. They are called extremal quasiconformal
maps, or Teichm\"{u}ller maps.
Although there are many efficient ways to compute or approximate conformal
maps, there is currently no such algorithm for extremal quasiconformal maps.
This paper studies the problem of computing extremal quasiconformal maps both
in the continuous and discrete settings.
We provide the first constructive method to obtain the extremal
quasiconformal map in the continuous setting. Our construction is via an
iterative procedure that is proven to converge quickly to the unique extremal
map. To get to within of the dilatation of the extremal map, our
method uses iterations. Every step of the iteration
involves convex optimization and solving differential equations, and guarantees
a decrease in the dilatation. Our method uses a reduction of the polygon
mapping problem to that of the punctured sphere problem, thus solving a more
general problem.
We also discretize our procedure. We provide evidence for the fact that the
discrete procedure closely follows the continuous construction and is therefore
expected to converge quickly to a good approximation of the extremal
quasiconformal map.Comment: 28 pages, 6 figure
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