Monday, February 27, 2023

Headlines For Me But Not For Thee


Axolotls can regenerate their brains, revealing secrets of brain evolution and regeneration
Sep 2022, phys.org

Researchers develop hierarchically self-assembled homochiral helical microtoroids
Nov 2022, phys.org

Jet lagged plants pave the way to first digital plant
Nov 2022, phys.org

Heart attack on a chip shows how heart changes after the event
Dec 2022, phys.org

Feline genetics help pinpoint first-ever domestication of cats
(Feline geneticist Leslie A. Lyons come on)
Dec 2022, phys.org


Everybody Loves Fermions


Graphs may prove key in search for Holy Grail of quantum error correction
Oct 2022, phys.org

It was a serendipitous discovery:

Quantum information is very fragile and prone to errors. You can't check for errors in a quantum system, because the act of checking itself collapses the system.

"The noise is very strong at the quantum scale," says Chapman. "And this makes quantum error correction very difficult."

You need some redundancy that allows you to tell if something has happened without knowing the underlying information."

There are quantum error correcting codes that are known to be self-healing, but they only work in four dimensions — one more than exists in this world. [right thanks]

In the new paper, the researchers showed that some subsystem codes can be represented as a certain kind of graph. [nodes and links]

"I had a seemingly unrelated pure mathematics project studying graph spectra," says Kollár, "and we realized that the numerical scripts that I had for that project could easily be modified to compute the energy cost of errors for the kinds of codes that Adrian and his collaborators had been looking at."

via Joint Quantum Institute: Adrian Chapman et al, Free-Fermion Subsystem Codes, PRX Quantum (2022). DOI: 10.1103/PRXQuantum.3.030321

Image credit: Anatoly Fomenko

The Revolution Will Be Fermions


Team develops graphene-based nanoelectronics platform
Dec 2022, phys.org

In metals, electric currents are carried by negatively charged electrons. But contrary to the researchers' expectations, their measurements suggested that the edge currents were not carried by electrons or by holes (a term for positive quasiparticles indicating the absence of an electron). Rather, the currents were carried by a highly unusual quasiparticle that has no charge and no energy, and yet moves without resistance. The components of the hybrid quasiparticle were observed to travel on opposite sides of the graphene's edges, despite being a single object.

The unique properties indicate that the quasiparticle might be one that physicists have been hoping to exploit for decades — the elusive Majorana fermion predicted by Italian theoretical physicist Ettore Majorana in 1937.

"Developing electronics using this new quasiparticle in seamlessly interconnected graphene networks is game changing," de Heer said.

via Georgia Institute of Technology: Vladimir S. Prudkovskiy et al, An epitaxial graphene platform for zero-energy edge state nanoelectronics, Nature Communications (2022). DOI: 10.1038/s41467-022-34369-4

Image credit: Anatoly Fomenko


The Topological Zoo


Is it topological? A new materials database has the answer
May 2022, phys.org

Topo is coming:

Harnessing the power of multiple supercomputers to map the electronic structure of more than 96,000 natural and synthetic crystalline materials to determine whether and what kind of topological traits exist in each structure.

Overall, they found that 90 percent of all known crystalline structures contain at least one topological property, and more than 50 percent of all naturally occurring materials exhibit some sort of topological behavior.

Topological Materials Database - periodic table of topology
Inorganic Crystal Structure Database - atomic and chemical structures of crystalline materials

via MIT, Princeton and the École Normale Supérieure Paris: Maia G. Vergniory et al, All Topological Bands of All Non-Magnetic Stoichiometric Materials, Science (2022). DOI: 10.1126/science.abg9094

Image credit: Topological Zoo - Anatoly Fomenko - 1967

Friday, February 24, 2023

Neuropsychedelia


Nicolas Langlitz is a penetrating wordsmith, a great writer, and one who can wrestle the meta better than most. (His other book is a study of the people who study primates, a meta-primatology study.)

Neuropsychedelia: The Revival of Hallucinogen Research Since the Decade of the Brain
Nicolas Langlitz, University of California Press, 2013

  • On the importance of the "principle of measured sloppiness" for experimental systems (see Rheinberger, Toward a History of Epistemic Things, Stanford, 1997) - sloppiness is what led Hofmann to "accidentally" discover LSD; he is usually meticulous in his bench work.
  • "The fact that hallucinogens make an organism more susceptible to its surroundings and the increased impressionability they induce bring about a situation in which locality and social context are strongly implicated in the findings of hallucinogen experiments." (p76) This is a good example of the meta-scientific lens, which is deployed expertly by Langlitz, especially in his book Cultural Primatology.
  • The problem with hallucinogens as medicine (and a valuable lesson for anyone interested in the burgeoning cannabis industry, both medicinal and recreational) - "From the pharmaceutical industry's point of view, the problem drugs are not the opiates or cocaine but the hallucinogens, the drugs so indelibly associated with the 1960s. The problem is not that these drugs could tell us a lot about ourselves and this knowledge might foment revolution, although these do seem to be possibilities. The problem is that with each dose every individual is likely to have a different experience. This is the very antithesis of quality as corporations currently define it. It seems difficult to see how hallucinogens can be brought into the area of standardization." (p77) Referencing The Creation of Pharmacology by David Healy in 2002. 
  • Describing participation in a psilocybin experiment: "For a moment, I felt irritated by the fact that my brain could do no better than imitate the geometric forms prevailing in psychedelic art." (p89)
  • The neuromolecular gaze - The Birth of the Neuromolecular Gaze by Abi-Rached et al in 2010
  • The neuralese dialect - "In its rejection of conventional manners of speaking and the corresponding social institutions, this radicalism, despite the different political undertones, was not so far removed from Timothy Leary's "neurological revolution," which had been propagated in an early neuralese dialect. (p205)
  • The neurochemical self - "One scientist who had just fallen in love was joking about his oxytocin level. E-mails were signed "seronteregically Yours." And after, I had given him the sociologist Nikolas Rose's (2003a) article of the same title to read, pharmacologist Felix Hasler began to speak of himself as a "neurochemical self."
  • Bioautomatons - "We're nothing but senseless bioautomatons!" (quoting Boris Quednow, p211)
  • On the Self:
Honza Samotar, Swiss physician of Czech descent who worked on 2 theses simultaneously: one on insect navigation with respect to potential applications in robotics, the other on the effects of hallucinogenic drugs on the human brain (p215) ... What distinguishes Samotar's mysticism of biology from the biology of the mystical (as investigated in neurotheological studies) is that its spiritual focal point is not the extraordinary mental states engendered by hallucinogenic drugs but rather the ordinary existence to which the self-experimenter eventually returns. (p218)

Honza Samotar: In my eyes, the mystical cannot be found in such ego dissolution experiences, which make you feel at one with everything. The truly mystical is that, when the drug effects wear off, you always return to your point of departure in everyday consciousness, to the baseline, so to speak. It's about the fact that I can lose myself in a state in which I'm not a human anymore, in which I lack both individuality and sociality, in which I have no lifetime because I'm eternal, being everything and nothing, neither dead nor alive, not divided into subject and object, not located in a universe with a beginning and an end -- and that this state eventually comes to an end, that I can even remember it. In retrospect, I then tell myself: yes, there are states in which I'm eternal, but then I'm not myself -- then it simply is, that state is. And strangely enough, I always come back here, to the same body at the same place. That's what I conceive of as mystical. (p219)

Image credit: AI Art - Neuropsychedelia - 2022



Wednesday, January 11, 2023

The Geometry of Information Space


New method to determine the dimensionality of complex networks through hyperbolic geometry
Oct 2022, phys.org

"The intrinsic geometry of data sets or complex networks is not obvious"

Infer the dimensionality of complex networks with hyperbolic geometrics, which captures the complexity of relational structures of the real world.

The study provides a multidimensional hyperbolic model of complex networks that reproduces its connectivity, with an ultra-low and customizable dimensionality for each specific network. This enables a better characterization of its structure—e.g., at a community scale—and the improvement of its predictive capability.

(configurational geometric model or SD model)

The study reveals unexpected regularities:
  • extremely low dimensions of molecular networks associated with biological tissues
  • slightly higher dimensionality required by social networks and the Internet
  • brain connectomes are close to three dimensions in their automatic organization

The model postulates a law of interconnection of the network elements (or nodes) that is gravitational, so nodes that are closer in a similarity space —of spherical geometry in D dimensions—and with more popularity—an extra dimension corresponding to the importance of the node—are more likely to establish connections."

In the study, the similarity and popularity variables are combined to give rise to the hyperbolic geometry of the model, which emerges as the natural geometry representing the hierarchical architecture of complex networks.

(It collapses the dimensions.)

"The Internet only requires D = 7 dimensions to be mapped into the hyperbolic space of our model, whereas this name is multiplied by six and scales to D = 47 in one of the most recent techniques using Euclidean space," says Professor Marián Boguñá.

via University of Barcelona: Pedro Almagro et al, Detecting the ultra low dimensionality of real networks, Nature Communications (2022). DOI: 10.1038/s41467-022-33685-z


The Synergistic Network Effect


The conspiracy theorist 'worldview' and the language of their argument
Oct 2022, phys.org

Conspiracies rely on other conspiracies as "evidence," jumping around different topics, less coherently than mainstream texts, but relying on a web of interconnected ideas to connect the dots.

The team analyzed thousands of conspiracist and mainstream webpages using natural language processing, a type of computer analysis of human language. They compared mainstream and conspiracist writing on the same topics.

Image credit: Network interconnectedness - conspiracy vs non-conspiracy - Alessandro Miani et al Science Advances 2022. https://dx.doi.org/10.1126/sciadv.abq3668

The synergistic network effect:
  • Believing that the AIDS virus was deliberately engineered in a government laboratory is associated with believing that the Federal Bureau of Investigation was involved in Martin Luther King’s assassination [16].
  • Conspiracy believers tend to identify meaningful relationships among randomly co-occurring events [17, 18]
  • “...the specifics of a conspiracy theory do not matter as much as the fact that it is a conspiracy theory at all” (p. 5, ft. 15, 21). 
Thus, belief in multiple conspiracies may be self-supporting: The interconnectivity among conspiracy beliefs is supported by a meta-belief that resolves the apparent contradictions at the lower level. Hence, conspiracy theories may thus constitute a mutually reinforcing network of beliefs, creating self-sustaining evidence for a world dominated by deceptive agents (15). 
(The meta-belief they're talking about is this -- authorities are intentionally deceptive, e.g., they're lying to us.)

  • Hypothesis 1: If a conspiracy worldview coerces unconnected observations to support for an overarching belief in the deceptive nature of authorities, then a network of potential conspiracy-related topics will be more tightly interconnected in conspiracy documents than in nonconspiracy documents.
  • Hypothesis 2a: If conspiracy narratives focus less on individual topics than nonconspiracy narratives, then topic specificity will be lower for conspiracy than nonconspiracy documents.
  • Hypothesis 2b: Text cohesion between paragraphs should be less internally cohesive for conspiracy documents than nonconspiracy documents.
  • Hypothesis 3: If conspiracy narratives reference similar worldviews, then similarity between documents should be higher for conspiracy documents (as a group) than nonconspiracy documents (H3).

15. M. J. Wood, K. M. Douglas, R. M. Sutton, Dead and alive. Soc. Psychol. Personal. Sci. 3, 767–773 (2012).
16. T. Goertzel, Belief in conspiracy theories. Polit. Psychol. 15, 731 (1994).
17.R. C. van der Wal, R. M. Sutton, J. Lange, J. P. N. Braga, Suspicious binds: Conspiracy thinking and tenuous perceptions of causal connections between co-occurring and spuriously correlated events. Eur. J. Soc. Psychol. 48, 970–989 (2018).; J.-W. van Prooijen, K. M. Douglas, C. De Inocencio, Connecting the dots: Illusory pattern perception predicts belief in conspiracies and the supernatural. Eur. J. Soc. Psychol. 48, 320–335 (2018).
18. J.-W. van Prooijen, K. M. Douglas, C. De Inocencio, Connecting the dots: Illusory pattern perception predicts belief in conspiracies and the supernatural. Eur. J. Soc. Psychol. 48, 320–335 (2018).
21. S. Lewandowsky, J. Cook, E. Lloyd, The ‘Alice in Wonderland’ mechanics of the rejection of (climate) science: Simulating coherence by conspiracism. Synthese 195, 175–196 (2018).

via University of Warwick and University of Neuchatel, Switzerland: Alessandro Miani et al, Interconnectedness and (in)coherence as a signature of conspiracy worldviews, Science Advances (2022). DOI: 10.1126/sciadv.abq3668

Post Script:
Language of Conspiracy (LOCO) - 88 million–word corpus composed of topic-matched conspiracy (N = 23,937) and nonconspiracy (N = 72,806) text documents (i.e., webpages) harvested from 150 websites.