arXiv research

Bayesian model predicts drip-line locations in heavy calcium isotopes.

A new model improves analysis of neural activity from calcium imaging.

Efficient method predicts coronary calcium scores in cardiac and chest CTs.

New methods estimate brain connectivity from calcium imaging data with missing data.

A fundamental challenge in calcium imaging has been to infer the timing of action potentials from the measured noisy calcium fluorescence traces. We systematically evaluate a range of spike inference algorithms on a large benchmark dataset recorded from varying neural tissue (V1 and retina) using different calcium indi…

Improved neural spike inference from calcium imaging data.

Researchers create a simulator to infer worm brain states from calcium imaging data.

Calcium imaging permits optical measurement of neural activity. Since intracellular calcium concentration is an indirect measurement of neural activity, computational tools are necessary to infer the true underlying spiking activity from fluorescence measurements. Bayesian model inversion can be used to solve this prob…

In this work, we propose a simple yet effective solution to the problem of connectome inference in calcium imaging data. The proposed algorithm consists of two steps. First, processing the raw signals to detect neural peak activities. Second, inferring the degree of association between neurons from partial correlation …

In this paper, we consider linear state-space models with compressible innovations and convergent transition matrices in order to model spatiotemporally sparse transient events. We perform parameter and state estimation using a dynamic compressed sensing framework and develop an efficient solution consisting of two nes…

New method estimates neuronal connectivity from partially observed data.

Calcium imaging has revolutionized systems neuroscience, providing the ability to image large neural populations with single-cell resolution. The resulting datasets are quite large, which has presented a barrier to routine open sharing of this data, slowing progress in reproducible research. State of the art methods fo…

Here we discuss an example of topologically isotopic but smoothly non-isotopic pair of 2-spheres in a simply connected 4-manifold, which become smoothly isotopic after stabilizing by connected summing with S^2 x S^2.

The paper finds infinitely many 4-manifolds with non-isotopic sections.

Study finds non-isotopic transverse tori in Engel manifolds.

Links with isotopic preimages in $S^3$ are isotopic in $RP^3$.

New obstructions show some 4-manifold homeomorphisms are pseudo-isotopic but not isotopic.

We construct infinite families of topologically isotopic but smoothly distinct knotted spheres in many simply connected 4-manifolds that become smoothly isotopic after stabilizing by connected summing with $S^2 \times S^2$, and as a consequence, analogous families of diffeomorphisms and metrics of positive scalar curva…

New ribbon disks in 4D space, non-isotopic to each other.

We construct infinitely many smooth oriented 4-manifolds containing pairs of homotopic, smoothly embedded 2-spheres that are not topologically isotopic, but that are equivalent by an ambient diffeomorphism inducing the identity on homology. These examples show that Gabai's recent "Generalized" 4D Lightbulb Theorem does…

Smoothly isotopic surfaces in a 4-manifold are stable isotopic if trivial in the 2-homology.

Low entropy hypersurfaces in 4D are isotopic to a sphere.

The paper explores isotopic triples of triangles in 3D space.

The paper introduces an inequality to detect when surfaces in 4-manifolds are not smoothly isotopic.

New spheres can split a 4D link in ways not possible in 3D.

New disks fill Legendrian knots without being smoothly isotopic.

New non-isotopic Seifert surfaces found in 4-ball.

We use the methods of Hedden, Juhasz, and Sarkar to exhibit a set of arborescent knots that bound large numbers of non-isotopic minimal genus spanning surfaces. In particular, we describe a sequence of prime knots K_{n} which will bound at least 2^{2n-1} non-isotopic minimal spanning surfaces of genus n.

In this paper, we study stable equivalence of exotically knotted surfaces in 4-manifolds, surfaces that are topologically isotopic but not smoothly isotopic. We prove that any pair of embedded surfaces in the same homology class become smoothly isotopic after stabilizing them by handle additions in the ambient 4-manifo…

The study constructs examples of pseudo-isotopic but not isotopic 4-manifold diffeomorphisms.

Given an $m$-component link $L$ in $S^3$ ($m \ge 2$), we construct a family of links which are link homotopic, but not link isotopic, to $L$. Every proper sublink of such a link is link isotopic to the corresponding sublink of $L$. Moreover, if $L$ is an unlink then there exist links that in addition to the above prope…

We give examples of contactomorphisms in every dimension that are smoothly isotopic to the identity but that are not contact isotopic to the identity. In fact, we prove the stronger statement that they are not even symplectically pseudo-isotopic to the identity. We also give examples of pairs of contactomorphisms which…

The study examines the realizability of a 4-manifold invariant for homeomorphisms.

BNNs enhance reservoir computing by acting as generalization filters.

We use microlocal sheaf theory to show that if two knots have Legendrian isotopic conormal tori, then the knots are isotopic or mirror images.

For any pair of integers $n\geq 1$ and $q\geq 2$, we construct an infinite family of mutually non-isotopic symplectic tori representing the homology class $q[F]$ of an elliptic surface E(n), where $[F]$ is the homology class of the fiber. We also show how such families can be non-isotopically and symplectically embedde…

We considered a surgery, called Lagrangian attaching disk surgery, that can be applied to a Lagrangian surface L at the presence of a Lagrangian attaching disk D, to obtain a new Lagrangian surface L' which is always smoothly isotopic to L. We showed that this type of surgery includes all even generalized Dehn twists a…

Every knot can be transformed into an unknot without cutting.

For each member of an infinite family of homology classes in the K3-surface E(2), we construct infinitely many non-isotopic symplectic tori representing this homology class. This family has an infinite subset of primitive classes. We also explain how these tori can be non-isotopically embedded as homologous symplectic …

New gauge theory invariant detects non-smooth isotopy of $P^2$-knots.

Manufacturing infinite sets of knotted and unknotted surfaces in 4-manifolds.

We show that after generic filling along a torus boundary component of a 3-manifold, no two closed, 2-sided, essential surfaces become isotopic, and no closed, 2-sided, essential surface becomes inessential. That is, the set of essential surfaces (considered up to isotopy) survives unchanged in all suitably generic Deh…

Paper presents a method for identifying isotope envelopes in MALDI-ToF data.

Infinitely many hyperbolic links in lens space have isotopic lifts in 3-sphere.

New surfaces in a 4-manifold are found that are not isotopic but homotopic.

Study weak conjugacy in surface homeomorphisms.

This paper presents a novel method for the reconstruction of a neural network connectivity using calcium fluorescence data. We introduce a fast unsupervised method to integrate different networks that reconstructs structural connectivity from neuron activity. Our method improves the state-of-the-art reconstruction meth…

New link pairs exist that can't be deformed without increasing length.