28 NOV 2024
09:00 - 17:00

Repetitive Transcranial Magnetic Stimulation (rTMS) - Workshop

28 NOV 2024
14:00 - 16:00

The class of finite structures is a notoriously ill-behaved one from the point of view of model theory. In the early years of this century, this led to the study of subclasses of this class which exhibit better behaviour. The focus was on classes defined by the sparsity of their underlying Gaifman graph. Such sparse classes were shown to be well-behaved in model-theoretic and algorithmic terms. The good behaviour discussed there focused on two aspects: that such classes show preservation properties that fail on the class of finite structures, and evaluation of first-order formulas is algorithmically tractable in such classes. A common theme is the use of the locality of first-order logic which, in the absence of compactness, is a key tool of finite model theory. More recent work has sought to extend this work to classes of finite structures that are not sparse, and identify tame classes of dense structures. This has seen a convergence with notions of tameness coming from stability theory.
In this talk, I review the use of locality in identifying tame classes; discuss the tameness of some sparse classes; and present some recent extensions to dense classes and the connections with stability.

Zoom room information:
https://us06web.zoom.us/j/81916335336?pwd=5zQT4lutMiBoY5Xp1pkFGtbqiaGozg.1
Meeting ID: 819 1633 5336
Passcode: 559618
Venue: Niavaran, Lecture Hall 1

27 NOV 2024
11:00 - 12:00

Abstract:

The pre-injector of the Iranian Light Source Facility consists of a radiofrequency electron gun, longitudinal and transverse focusing magnets, linear accelerators, and several other ancillary parts. Since the emittance of the ILSF electron beam at the end of the linear accelerators reaches about 8 mm-mrad, we intend to achieve a lower emittance by designing an electrostatic electron gun. Also, electrostatic electron gun pre-injectors do not require alpha magnets and instead have several beam bunchers, contributing to this type's lower emittance.

Reducing the emittance in the electron pre-injector does not have much effect on reducing the emittance in the storage ring. However, the more we can minimize the beam emittance at the beginning of its production, the better. Because the beam emittance may gradually increase along the path. Reducing the emittance of the pre-injector leads to a reduction in the dimensions of the vacuum chamber and the opening of the magnets in the booster ring, and reduces the cost of the magnets and their energy consumption.
In this study, we try to design a high-current electrostatic electron gun with low emittance and investigate the electron beam dynamics and beam emittance with the SPIFFE code and GPT code.

Based on:
https://link.aps.org/pdf/10.1103/PhysRevAccelBeams.20.043403, https://doi.org/10.1016/j.nima.2023.168198

Indico Link:
https://indico.hep.ipm.ir/e/h.rafiei

Meeting Place:
Seminar Room, School of Particles and Accelerators, IPM

Link to Join Virtually:
https://www.skyroom.online/ch/ipm-particles/weekly-seminar

27 NOV 2024
14:00 - 15:00

Blockchains provide the opportunity for the first large permission-less trust-less distributed network. In this talk, we review the basic working principles of blockchains, which provide the infrastructure of cryptocurrencies, like Bitcoin. Although, the security features of such a system are promising, other performance metrics such as throughput and delay do not scale with the network size. We will discuss the basic scaling limitations and the proposed solutions. Finally, we review the Proof-of-Stake (PoS) method which is the main alternative for the traditional Proof-of-Work (PoW) scheme, and discuss its main benefits and challenges.

Zoom room information:
https://us06web.zoom.us/j/85237260136?pwd=MFSZoKdmRXAjfaSaBzbf19lTaaKglf.1
Meeting ID: 852 3726 0136
Passcode: 362880
Venue: Niavaran, Lecture Hall 1

27 NOV 2024
17:30 - 19:00

The known results about the rationality vs irrationality of smooth Fano complete intersections $X^nsubsetmathbb P^{n+c}$ of dimension $n=3,4,5$ and fixed type $(d_1,ldots, d_c)$ suggest an uniform approach to treat several open cases: index one; index two; quartic fourfolds and fivefolds; etc. From one hand one would like to decide the rationality/irrationality of every element in the numerous cases where the stable irrationality of the very general element is known (e.g. quartic fourfolds and fivefolds, quintic fivefolds, etc); from the other hand one hopes to put some further light on several longstanding conjectures (e.g. the irrationality of the very general cubic fourfold). After an introduction of the general problem and after recalling the state of the art, we shall present some of our recent results on these topics.

https://zoom.us/join
Meeting ID: 9086116889
Passcode: 362880
Email: agnt@ipm.ir
Venue: , (Zoom Lecture)

27 NOV 2024
14:00 - 15:00


Interfacial coatings by, e.g., polymers, are often used to modify surface interactions of materials, or to protect the underlying substrate. Self-assembling polymer coatings find use e.g., as protective layers in biomedical applications, as anti-corrosion coats protecting metallic surfaces, but also as preservative layers conserving stone materials in architectural monuments. Advanced uses require control of the assembling structure and coating spreading. Computational modelling provides an effective means to reveal guidelines for these, e.g., in terms of polymer component choices, their miscibilities, or degree of polymerization.

Here, we employ dissipative particle dynamics (DPD) simulations to study the self-assembly of protective polymeric coatings and their structures. We focus on a model system composed of a hydrophilic surface coated via self-assembly of linear amphiphilic di-block copolymers and linear hydrophobic polymers. The model substrate matches cellulose, while the hydrophilic segments represent starch, and the hydrophobic material a random co-polymer of styrene and n-butyl acrylate (at equal weight ratio). Our results show that copolymers with equal block lengths form stable, well-ordered lamellar surface coatings, while block length asymmetry leads to advanced patterning in the coating. We examine the effect of concentration, extracting coating spreading and optimal concentration trends for uniform complete coatings, and map the sensitivity of the assembly to chemical composition by varying the DPD interaction parameters. Our work provides guidelines for tuning and controlling the self-assembly of polymeric coatings and their internal structures for surface modifying applications.


Click the link to join this webinar


https://www.skyroom.online/ch/schoolofnanoscience/weeklyseminars

26 NOV 2024
14:00 - 15:00

Date and time

Tuesday, November 26th, 2024 (Azar 6th, 1403), 2:00 pm (Tehran zone)




Link

https://www.skyroom.online/ch/schoolofphysics/highenergyseminar



Abstract
In this talk, I will outline a fundamentally quantum description of bosonic dark matter. Following a quantum optics inspired approach, I will show the density operator of dark matter, which takes a mixed Gaussian form over a coherent state basis. This formalism also allows a precise description of quantities related to dark matter coherence. I will further give a continuous description of dark matter through the wave-particle transition, where the density fluctuation in various scales evolves between the two limits, showing a unique behavior near the boundary of these descriptions.