#anisotropy

[materialsscienceandengineering]

Spintronics memory innovation: A new perpendicular magnetized film

Long gone are the days where all our data could fit on a two-megabyte floppy disk. In today's information-based society, the increasing volume of information being handled demands that we switch to memory options with the lowest power consumption and highest capacity possible. Magnetoresistive Random Access Memory (MRAM) is part of the next generation of storage devices expected to meet these needs. Researchers at the Advanced Institute for Materials Research (WPI-AIMR) investigated a cobalt-manganese-iron alloy thin film that demonstrates a high perpendicular magnetic anisotropy (PMA)—key aspects for fabricating MRAM devices using spintronics. The findings were published in Science and Technology of Advanced Materials on November 13, 2024. "This is the first time a cobalt-manganese-iron alloy has strongly shown large PMA," says Professor Shigemi Mizukami (Tohoku University),

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[dnieperrobot69420]

Taking a slight tangent from classical optics, I decided to delve more into non-linear optics.

As someone who never had to use Gaussian form of Maxwell's equations, never used Tensors, and had never used Einsteins notation for summation; let me just say the algebra of the book proved to be a hard nut to crack!

What am I learning about? Anisotropy! Who knew that the direction at which you observe/propagate through a material such as a crystal plays a role in the material properties you will experience!!

I still don't believe you can determine eigenvalues and eigenvectors for an arbitrary 3x3 permittivity matrix (I need to use numerical examples to really see it) and that there exists rotational matricies that let us make the math all neat and proper.

But, slowly and with growing pains, I am continuing to slowly tread the waters of this fascinating topic!

[truphysics]

Anisotropy

Introduction Anisotropy refers to the property of being directionally dependent. In other words, a material is said to be anisotropic if its physical or mechanical properties vary when measured along different directions. This is in contrast to isotropy, where properties do not change regardless of the direction in which they are measured. A physically anisotropic pattern. The physical…

[whats-in-a-sentence]

Initial measurements of the microwave background radiation revealed its temperature to be remarkably uniform, but as we discussed in Chapter 11, closer inspection, first achieved in 1992 by the Cosmic Background Explorer (COBE) and since improved by a number of observational undertakings, found evidence of small temperature variations, as illustrated in Figure 14.4a. The data are gray-scale coded, with light and dark patches indicating temperature variations of about a few ten-thousandths of a degree.

In 2001, the Wilkinson Microwave Anisotropy Probe (WMAP) satellite, a joint venture of NASA and Princeton University, was launched to measure the microwave background radiation with about forty times COBE's resolution and sensitivity. By comparing WMAP's initial results, Figure 14.4b, with COBE's, Figure 14.4a, you can immediately see how much finer and more detailed a picture WMAP is about to provide.

"The Fabric of the Cosmos" - Brian Greene

[sundowngroup]

Who else is a part of this group, anyway?

BBH: That's actually a very good question!

BBH: Working off the assumption that absolutely *nobody* out there knows who we are...

BBH: There's myself, of course. I'm the senior of the Sundown Group. Then there's my own senior Flocks to the South, who... I will spare you the details on her fate. She is no longer with us. She never was.

BBH: Then we have Bolides Ejecta Anisotropy, a nearby botanical facility situated within a dense rain forest. They're my closest friend in my group, and they currently host a large population of scavengers. The largest I've ever seen or heard of!

BBH: After them, there's Looping Curiosity, who...

BBH: ...

BBH: Actually, I don't remember what Looping Curiosity did while our creators were around! What I do know is that he suffered an injury that permanently damaged his systems, so his memory isn't fantastic. But that's alright. My own memory isn't what it used to be either.

BBH: Ahem. Then there's Ultraviolet Eclipses, who... I believe was a communications hub in her prime? I'm not sure. They've never told me. I'm not especially close with it, you see.

BBH: After that is Voice of Silence. She's a rather unique case in our group. There's some kind of error with her voice, limiting her to only a few words for every spoken sentence.

BBH: I think that's everyone! I hope that one day I'll be able to open up this relay to them so they can speak to outsiders as well!

[reddpenn]

Do you have any thoughts about cyanite? I'm reading a book wherein some characters are given rock-related names for worldbuilding reasons, and it seemed an interesting choice for a protagonist's name, with implications that probably elude me. (Other characters' names include feldspar and alabaster.) (I like when stories do this kind of thing, there are a lot of cool names for different rocks.)

Oooh, that's an incredibly interesting name for a protagonist! Cyanite is a variation on kyanite, which is this blue mineral:

And an archaic name for kyanite was disthene, a Greek word meaning "two strengths." It was called this because kyanite has this super interesting property called anisotropy.

Anisotropic minerals have two different numbers on the mohs scale, the scale that measures the hardness and scratch resistance of minerals. When scratched against the grain, kyanite has a mohs hardness of 7, about as hard as quartz. But when scratched along the grain, kyanite only has a hardness of 4.5, as soft as fluorite!

(I have actually done hardness testing on kyanite, it is wild how different the durability becomes just by rotating the stone.)

Anyway, back to your book! Maybe by naming the character Cyanite, the author is alluding to the fact that they're a strong character with a secret, catastrophic weakness. Or maybe they're a weak character with a lot of hidden strength!

[wumblr]

quanta magazine: standard model survives JWST's surprising finds

big think: dipole anomaly affecting the entire universe?

In the following days, dozens of galaxy candidates from CEERS and GLASS sprung into view with estimated redshifts as high as 20—just 180 million years after the big bang—some with disklike structures that were not expected to manifest so early in cosmic history. Another team, meanwhile, found evidence for galaxies the size of our Milky Way at a redshift of 10, less than 500 million years after the big bang. Such behemoths emerging so rapidly defies expectations set by cosmologists’ standard model of the universe’s evolution. Called Lambda CDM (LCDM),

[covid-safer-hotties]

Reference archived on our website

Highlights • Long-COVID is heterogeneous in its symptoms, severity, and illness duration. • There was no association between long-COVID and cognitive performance. • Cognitive symptoms may represent functional cognitive disorders. • Long-COVID had lower mean diffusivity on diffusion imaging than normal recovery. • Diffusion imaging differences may suggest gliosis as a mechanism of long-COVID.

To be clear: There was no cognitive difference between people post infection. I can see some people misunderstanding what this says. It says there is some form of brain damage from covid across the board, even if you don't have long covid symptoms or diagnosis.

Abstract

Background

The pathophysiology of protracted symptoms after COVID-19 is unclear. This study aimed to determine if long-COVID is associated with differences in baseline characteristics, markers of white matter diffusivity in the brain, and lower scores on objective cognitive testing.

Methods

Individuals who experienced COVID-19 symptoms for more than 60 days post-infection (long-COVID) (n = 56) were compared to individuals who recovered from COVID-19 within 60 days of infection (normal recovery) (n = 35). Information regarding physical and mental health, and COVID-19 illness was collected. The National Institute of Health Toolbox Cognition Battery was administered. Participants underwent magnetic resonance imaging (MRI) with diffusion tensor imaging (DTI). Tract-based spatial statistics were used to perform a whole-brain voxel-wise analysis on standard DTI metrics (fractional anisotropy, axial diffusivity, mean diffusivity, radial diffusivity), controlling for age and sex. NIH Toolbox Age-Adjusted Fluid Cognition Scores were used to compare long-COVID and normal recovery groups, covarying for Age-Adjusted Crystallized Cognition Scores and years of education. False discovery rate correction was applied for multiple comparisons.

Results

There were no significant differences in age, sex, or history of neurovascular risk factors between the groups. The long-COVID group had significantly (p < 0.05) lower mean diffusivity than the normal recovery group across multiple white matter regions, including the internal capsule, anterior and superior corona radiata, corpus callosum, superior fronto-occiptal fasciculus, and posterior thalamic radiation. However, the effect sizes of these differences were small (all <|0.3|) and no significant differences were found for the other DTI metrics. Fluid cognition composite scores did not differ significantly between the long-COVID and normal recovery groups (p > 0.05).

Conclusions

Differences in diffusivity between long-COVID and normal recovery groups were found on only one DTI metric. This could represent subtle areas of pathology such as gliosis or edema, but the small effect sizes and non-specific nature of the diffusion indices make pathological inference difficult. Although long-COVID patients reported many neuropsychiatric symptoms, significant differences in objective cognitive performance were not found.

[wangmiao]

OK...I discovered something interesting about our ship 史汪/Shiwang in relation to two comets also with the Chinese name 史汪 on weibo, and I kinda looked into these two comets. So here's some fun facts:

First of all, we all know our ship name is Shiwang/史汪 from Shi Qiang and Wang Miao's names, and because it sounds quite similar to the English word "swan", there're some fans also calling the ship swan on weibo, especially when they don't want their posts to be searchable with Shiwang.

Comet C/2006 M4 (SWAN), were discovered in June 2006, and Liu Cixin's Three Body Problem first started to get published on a sci-fi magazine in May 2006. This comet is a non-period comet which means it only passes through the solar system once, and makes me think of Shi Qiang and Wang Miao only passed through each other's lives once in the book canon.

C/2020 F8 (SWAN), or Comet SWAN were discovered in May 2020, and Tencent's Three-Body started shooting in June 2020. This is an oort cloud comet which is the most long-period comet, and it takes more than 200 years for them to orbit around the sun. Does it remind you of Shi Qiang sleeping for 200 years?

These comets were named SWAN because their photos were taken by Solar Wind Anisotropies (SWAN), and the Chinese translation is 史汪, with exactly the same Chinese characters as the ship name. So they are called "史汪彗星".

Shiwang's story only lasted a month in canon, and it's interesting that the discovery date and the publishing/shooting date also had roughly a month in between them. And since comets are known to glow green and blue (in the case of the 2020 comet, it has a green comet head and a blue comet tail), somehow this series of Three-Body character posters have green and blue as the theme color for Shiwang (in this series of posters, 3/11 are blue, 2/11 are green) :

I know this is all a coincidence, but it's a beautiful and epic one. It just makes Shiwang even more like a sci-fi romance or space romance...It's like the entire universe is rooting for them. Now you can go brag about how there are TWO comets for your ship!

[materialsscienceandengineering]

Room-temperature superconductivity: Researchers uncover optical secrets of Bi-based superconductors

Copper-oxide (CuO2) superconductors, such as Bi2Sr2CaCu2O8+δ (Bi2212), have unusually high critical temperatures. Optical reflectivity measurements of Bi2212 have shown that it exhibits strong optical anisotropy. However, this has not been studied through optical transmittance measurements, which can offer more direct insights into bulk properties. Now, researchers have elucidated the origin of this optical anisotropy through ultraviolet and visible light transmittance measurements of lead-doped Bi2212 single crystals, enabling a more precise investigation into its superconductivity mechanisms. Their research is published in the journal Scientific Reports. Superconductors are materials which conduct electricity without any resistance when cooled down below a critical temperature. These materials have transformative applications in various fields, including electric motors, generators, high-speed maglev trains, and magnetic resonance imaging.

Read more.

[dnieperrobot69420]

What have I been up to? Well more or less more optics.

I started to learn about the Index Ellipsoid, and I am beginning to understand how we can quantify a materials allowed polarizations using the "indicatrix" (not going to lie this is a hard word to spell lol)

I now understand that there are two possible electric flux densities (basically the quadratic equations +/- gives two roots, so when you solve for two possible refractive indices, you also get two D solutions) and that these two fluxes are orthogonal.

The index Ellipsoid let's us characterize anisotropic crystals into biaxial (two defined optical axes) and uniaxial (two axes are equal)

But honestly, I'm hitting a bit of a wall here. I just want to be familiar with the material before grad school starts. Since I'm self studying now, I decided to venture off into a related topic: Computational electromagnetics!!

I took numerical methods this winter so when I heard about Finite Difference Method I didn't look like a 🦌 staring at 🚗 lol (honestly I find Runge-Kutta methods scarier haha)

So I learned a bit about collocated grids, recalled Dirichlet boundary conditions, periodic boundary conditions as well as Neuman boundary conditions.

My plan is to use COMSOL multi physics to do a little simulation for my masters thesis, so I'm betting that having a grasp on the numerical side of emag is something I need to accomplish to bear fruitful results.

And of course I get hit with the realization exactly *why* plane waves are used to teach us optics: because they are simply a stepping stone towards us learning about Gaussian Beams!

The 🐇 hole just keeps getting deeper and deeper... 🕳️

[livingforstars]

NASA Mission to MAP the Universe - April 15th, 1996.

"What is our Universe made of? How rapidly is our Universe expanding? When did galaxies form? These questions, among the most baffling to astronomers since the beginning of the modern astronomical era, might well be answered by new space satellite missions. The Microwave Anisotropy Probe (MAP) was designed to inspect the Universe's microwave background radiation in more detail then ever before. MAP was to record the frequency, size and temperature of bumps 20 times smaller than COBE. Astronomers had computed what bumps would be expected from several models of our Universe, and comparing these results to MAP's data was predicted to yield a new understanding of the composition and structure of our Universe."

[sharlmbracta]

well hello there

eeeeaaaaahhhhh

welp i tried

anisotropy is weird

[caehum]

Blown away by the hair in your models (and your models in general tbh, but hair has always been tricky for me). What technique do you use to make them? Do you just use the add hair sculpting feature that introduced in V3 (I find it hard to stylize, but that’s my best guess)? The strands in your models, all of it, are really incredible. You’re very talented. <3 Apologies if this has been asked before.

thank you! since i mostly work with anime styled hair (ripped straight from kh3 most of the time) it's usually structured like this

shading something like this procedurally is kinda tricky at first but surprisingly simple when i found out that messing with this anisotropy slider gives the illusion of many strands when you render it out

i made this node setup as basic as possible so it could be copied by anyone. hope i could help!!

[weakfleshwillingsoul]

First person in the lab today 8am morning besides my old man prof who drives here for 45min to make it for 7am. Chromatograph like a beautiful dream. Imaged the gel, some degradation apparent but otherwise looking okay. Days bleeding together with the only distinguishing factor being the progressively improving data. Concentrating A04 for a little while longer with the hopes of making it to 200uM before I lose too much volume. Going ahead with the fluorescence anisotropy assay by this afternoon. Will have the results for you hopefully by 3pm!