13 AUG 2020
18:00 - 19:00

One of the most fruitful directions in the study of monomial ideals is finding
topological objects whose chain maps can be adapted to a free resolution of the ideal. The
catalyst of this approach was the Taylor resolution of a monomial ideal, which is supported
on a simplicial complex, but is largely non-minimal. While not all monomial ideals have
minimal free resolutions supported on a simplicial (or even CW) complex, it is known that a
square-free monomial ideal of projective dimension one has a minimal free resolution
supported on a tree. We show that the powers of such an ideal have minimal free resolutions
that are supported on related polyhedral cell complexes, that can be constructed from this
tree. In the process, we provide a full description of the Rees Algebra of the ideal. (This is
joint work with S. Cooper, S. El Khoury, S. Faridi, S. Mayes-Tang, S. Morey and S. Spiroff).


(Access link will be announced by email a day before the webinar dates.)

13 AUG 2020
15:00 - 17:00

Abstract:
The title of the talk is a quote from Einstein in challenging the Copenhagen interpretation of quantum mechanics, where it is believed that physical realities before measurement do not exist. Where does this idea come from? How much reliable is it? In the case where physical realities do exist before measurement, what are their properties? These questions are among those that we are going to deal with in the coming presentation. In this regard, after introducing the framework of the ontological models of quantum mechanics, we will look at the reality of the wave function, completeness of the wave function, locality, contextuality and determinism in these models.

Speaker:
Dr. Mahdi Ramezani
Sharif University of Technology

Date: Thursday, August 13, 2020
Time: 15-17
Link of the meeting room:
https://www.skyroom.online/ch/schoolofphysics/foundations-of-physics

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13 AUG 2020
11:00 - 12:00

Abstract: The Weinberg's asymptotic safety conjecture predicts that the quantum theory does not diverge if its running coupling tends to a non-Gaussian fixed point at the UV limit. Using the functional renormalization group methods, Reuter predicts antiscreening terms for the gravitational running coupling which tends to mentioned non-Gaussian fixed point.
Although it is expected that studying the effects of this renormalization method could be done by studying the solution of the exact renormalization group equation, effective average action, but, it seems too complicate to derive if not impossible. Thus, it is claimed that the improvement of typical coupling constant $g_0$ to running one $g_k$ in the classical theory, can restore the effects of quantum loops to some extent.
In this talk, first I will review this conjecture and the new method of the action improvement using the curvature invariants. Then the effects of this method on the improved Mukhanov-Sasaki equation and the improved energy condition will be discussed.


https://www.skyroom.online/ch/ipm-particles/hep-th

12 AUG 2020
18:00 - 19:30

Organized by: School of Cognitive Sciences
to receive the link to join online, please send email to theoretical.neurosci.ipm@gmail.com

Abstract:

In the realization of brain implants and neural prostheses, one of the main challenges is to increase the number of recording channels. This is mainly because of the significant increase in the need for power consumption, data telemetry bandwidth, and also enlarged physical dimension of the neural recording implant. On-implant spike sorting is one of the possible steps towards overcoming such challenges by efficient data reduction.


On-implant spike sorting methods employ static feature extraction/selection techniques to minimize the hardware cost. Here we propose a novel framework for real-time spike sorting based on dynamic selection of features. We select salient features that maximize the geometric-mean of between-class distances as well as the associated homogeneity index effectively to best discriminate spikes for classification. Wave-shape classification is performed based on a multi-label window discrimination approach. An external module calculates the salient features and discrimination windows through optimizing a replica of the on-implant operation, and then configures the on-implant spike sorter for real-time online operation. Hardware implementation of the on-implant online spike sorter for 512 channels of concurrent extra-cellular neural signals is reported, with an average classification accuracy of ~88%. Compared with other similar methods, our method shows reduction in classification error by a factor of ~2 and also reduction in the required memory space by a factor of ~5.


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