Role of statistical symmetries in sensory coding: an optimal scale invariant code for vision

2003 ◽  
Vol 97 (4-6) ◽  
pp. 491-502 ◽  
Author(s):  
Antonio Turiel ◽  
Néstor Parga
2017 ◽  
Vol 26 (01n02) ◽  
pp. 1740023 ◽  
Author(s):  
Mannque Rho

I describe the long-standing search for a “smoking-gun” signal for the manifestation of (scale-)chiral symmetry in nuclear interactions. It is prompted by Gerry Brown’s last unpublished note, reproduced verbatim below, on the preeminent role of pions and vector ([Formula: see text]) mesons in providing a simple and elegant description of strongly correlated nuclear interactions. In this note written in tribute to Gerry Brown, I first describe a case of an unambiguous signal in axial-charge transitions in nuclei and then combine his ideas with the more recent development on the role of hidden symmetries in nuclear physics. What transpires is the surprising conclusion that the Landau–Migdal fixed point interaction [Formula: see text], the nuclear tensor forces and Brown–Rho scaling, all encoded in scale-invariant hidden local symmetry, as Gerry put, “run the show and make all forces equal.”


2020 ◽  
Vol 32 (3) ◽  
pp. 386-402
Author(s):  
Talya Sadeh ◽  
Yoni Pertzov

After over 100 years of relative silence in the cognitive literature, recent advances in the study of the neural underpinnings of memory—specifically, the hippocampus—have led to a resurgence of interest in the topic of forgetting. This review draws a theoretically driven picture of the effects of time on forgetting of hippocampus-dependent memories. We review evidence indicating that time-dependent forgetting across short and long timescales is reflected in progressive degradation of hippocampal-dependent relational information. This evidence provides an important extension to a growing body of research accumulated in recent years, showing that—in contrast to the once prevailing view that the hippocampus is exclusively involved in memory and forgetting over long timescales—the role of the hippocampus also extends to memory and forgetting over short timescales. Thus, we maintain that similar rules govern not only remembering but also forgetting of hippocampus-dependent information over short and long timescales.


2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Shubo Wang ◽  
Bo Hou ◽  
Che Ting Chan

Abstract Metamaterials have enabled the design of electromagnetic wave absorbers with unprecedented performance. Conventional metamaterial absorbers usually employ multiple structure components in one unit cell to achieve broadband absorption. Here, a simple metasurface microwave absorber is proposed that has one metal-backed logarithmic spiral resonator as the unit cell. It can absorb >95% of normally incident microwave energy within the frequency range of 6 GHz–37 GHz as a result of the scale invariant geometry and the Fabry-Perot-type resonances of the resonator. The thickness of the metasurface is 5 mm and approaches the Rozanov limit of an optimal absorber. The physics underlying the broadband absorption is discussed. A comparison with Archimedean spiral metasurface is conducted to uncover the crucial role of scale invariance. The study opens a new direction of electromagnetic wave absorption by employing the scale invariance of Maxwell equations and may also be applied to the absorption of other classical waves such as sound.


1997 ◽  
Vol 12 (06) ◽  
pp. 371-380 ◽  
Author(s):  
Yasunori Fujii

We show that regularizing divergent integrals is important when applied to the loop diagrams corresponding to quantum corrections to the coupling of the "gravitational" scalar field due to the interaction among matter fields. We use the method of continuous spacetime dimensions to demonstrate that WEP is a robust property of the Brans–Dicke theory beyond the classical level, hence correcting our previous assertion of the contrary. The same technique can be used to yield the violation of WEP when applied to the scale-invariant theory, thus providing another reason for expecting fifth-force-type phenomena.


2020 ◽  
Author(s):  
Ikaasa Suri ◽  
Patrick McGranor Wilson ◽  
Saba Doustmohammadi ◽  
Anna De Schutter ◽  
Thida Sandy Chunwatanapong ◽  
...  

AbstractUnder covert attention, our visual perception deteriorates dramatically as eccentricity increases. This reduction of peripheral visual acuity (PVA) is partially due to the coarse sampling of the retinal ganglion cells towards the periphery, but this property cannot be solely responsible. Other factors, such as character crowding, have been studied, yet the origin of the poor PVA is not entirely understood. This gap motivated us to investigate the PVA by varying the crowding conditions systematically. Under completely crowded conditions (i.e. resembling a full page of text), PVA was observed to be eight times worse than the PVA under uncrowded conditions. By partially crowding the periphery, we obtained PVA values between the fully crowded and uncrowded conditions. On the other hand, crowding the fovea center while leaving the periphery uncrowded improved PVA relative to the uncrowded case. These results support a model for a top-down “covert attention vector” that assists the resulting PVA in a manner analogous to saccadic eye movement for overt attention. We speculate that the attention vector instructs the dorsal pathway to transform the peripheral character to the foveal center. Then, the scale-invariant log-polar retinotopy of the ventral pathway can scale the centered visual input to match the prior memory of the specific character shape.


2018 ◽  
Vol 21 (03n04) ◽  
pp. 1850014 ◽  
Author(s):  
ALESSANDRO PLUCHINO ◽  
ALESSIO EMANUELE BIONDO ◽  
ANDREA RAPISARDA

The largely dominant meritocratic paradigm of highly competitive Western cultures is rooted on the belief that success is mainly due, if not exclusively, to personal qualities such as talent, intelligence, skills, smartness, efforts, willfulness, hard work or risk taking. Sometimes, we are willing to admit that a certain degree of luck could also play a role in achieving significant success. But, as a matter of fact, it is rather common to underestimate the importance of external forces in individual successful stories. It is very well known that intelligence (or, more in general, talent and personal qualities) exhibits a Gaussian distribution among the population, whereas the distribution of wealth — often considered as a proxy of success — follows typically a power law (Pareto law), with a large majority of poor people and a very small number of billionaires. Such a discrepancy between a Normal distribution of inputs, with a typical scale (the average talent or intelligence), and the scale-invariant distribution of outputs, suggests that some hidden ingredient is at work behind the scenes. In this paper, we suggest that such an ingredient is just randomness. In particular, our simple agent-based model shows that, if it is true that some degree of talent is necessary to be successful in life, almost never the most talented people reach the highest peaks of success, being overtaken by averagely talented but sensibly luckier individuals. As far as we know, this counterintuitive result — although implicitly suggested between the lines in a vast literature — is quantified here for the first time. It sheds new light on the effectiveness of assessing merit on the basis of the reached level of success and underlines the risks of distributing excessive honors or resources to people who, at the end of the day, could have been simply luckier than others. We also compare several policy hypotheses to show the most efficient strategies for public funding of research, aiming to improve meritocracy, diversity of ideas and innovation.


2022 ◽  
Author(s):  
Adrian F. Tuck

A method of calculating the Gibbs Free Energy (Exergy) for the Earth’s atmosphere using statistical multifractality — scale invariance - is described, and examples given of its application to the stratosphere, including a methodology for extension to aerosol particles. The role of organic molecules in determining the radiative transfer characteristics of aerosols is pointed out. These methods are discussed in the context of the atmosphere as an open system far from chemical and physical equilibrium, and used to urge caution in deploying “solar radiation management”.


2005 ◽  
Vol 272 (1572) ◽  
pp. 1571-1576 ◽  
Author(s):  
Frédéric Guichard

Species interactions and connectivity are both central to explaining the stability of ecological communities and the problem of species extinction. Yet, the role of species interactions for the stability of spatially subdivided communities still eludes ecologists. Ecological models currently address the problem of stability by exploring the role of interaction strength in well mixed habitats, or of connectivity in subdivided communities. Here I propose a unification of interaction strength and connectivity as mechanisms explaining regional community stability. I introduce a metacommunity model based on succession dynamics in coastal ecosystems, incorporating limited dispersal and facilitative interactions. I report a sharp transition in regional stability and extinction probability at intermediate interaction strength, shown to correspond to a phase transition that generates scale-invariant distribution and high regional stability. In contrast with previous studies, stability results from intermediate interaction strength only in subdivided communities, and is associated with large-scale (scale-invariant) synchrony. These results can be generalized to other systems exhibiting phase transitions to show how local interaction strength can be used to resolve the link between regional community stability and pattern formation.


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