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NotTheMacAnon
@NotTheMacAnon1 3 years, 3 months ago 479 views

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In continuum mechanics, stress is a physical quantity that expresses the internal forces that neighbouring particles of a continuous material exert on each other, while strain is the measure of the deformation of the material.

For example, when a solid vertical bar is supporting an overhead weight, each particle in the bar pushes on the particles immediately below it. When a liquid is in a closed container under pressure, each particle gets pushed against by all the surrounding particles.

The container walls and the pressure-inducing surface (such as a piston) push against them in (Newtonian) reaction.

These macroscopic forces are actually the net result of a very large number of intermolecular forces and collisions between the particles in those molecules. Stress is frequently represented by a lowercase Greek letter sigma (σ).

Residual stresses inside a plastic protractor are revealed by the polarized light.

Strain inside a material may arise by various mechanisms, such as stress as applied by external forces to the bulk material (like gravity) or to its surface (like contact forces, external pressure, or friction).

Any strain (deformation) of a solid material generates an internal elastic stress, analogous to the reaction force of a spring, that tends to restore the material to its original non-deformed state.

In liquids and gases, only deformations that change the volume generate persistent elastic stress.

However, if the deformation changes gradually with time, even in fluids there will usually be some viscous stress, opposing that change. Elastic and viscous stresses are usually combined under the name mechanical stress.

Significant stress may exist even when deformation is negligible or non-existent (a common assumption when modeling the flow of water). Stress may exist in the absence of external forces; such built-in stress is important, for example, in prestressed concrete and tempered glass.

Stress may also be imposed on a material without the application of net forces, for example by changes in temperature or chemical composition, or by external electromagnetic fields (as in piezoelectric and magnetostrictive materials).

Virial stress 🧐 is a measure of mechanical stress on an atomic scale for homogeneous systems.

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NotTheMacAnon
@NotTheMacAnon1

During a normal pregnancy, oxidative stress enhances antioxidant mechanisms that are capable of reacting by way of enzyme activity and non-enzyme free radical deactivators. However, pregnancy is also a state in which this adaptation and balance may be easily disrupted.

There is strong evidence that a chronicin flammatory reaction combined with the presence of a local oxidizing environment may play a vital role in the etiology and development of complications during pregnancy.

In late pregnancy, damage to DNA (especially when it is caused by oxidative stress) is associated with pre-eclampsia(PE), intrauterine growth restriction (IUGR), and the death of mothers in developing countries; it largely determines pregnancy – related susceptibility to diseases

The referential values of ROS and NOS and their minimal and safe concentrations or physiologically beneficial concentrations are yet to be determined.

The measurement of oxidative stress in vivo is perceived as controversial,

as the sen-sitivity and specificity of various oxidative stress markers is unknown.. .

NotTheMacAnon
@NotTheMacAnon1

2020 marks the start of the quantum dot revolution.

Completely ignoring the fact that "photocatalytic generation of reactive oxygen species (ROS) from quantum dots (QDs) has been widely reported."

Results: It was found that whereas singlet oxygen (1O2) was not produced by photoexcited QDs, superoxide anion(O2− )and hydroxyl radicals(OH) were generated by QDs, especially in the presence of a physiological concentration of electron donating agent including NADH.

Using cell metabolic activity assays and various probes of ROS generation, the formation of ROS in cellular environments was demonstrated.

Conclusion: Illumination of QD-treated cells and bacteria with light did affect viability. The above results, together with those of assays in the presence of various scavengers of specific ROS, indicate that the formation of ROS by QDs mainly proceeded via electron transfer.

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NotTheMacAnon
@NotTheMacAnon1

"When does a canary sing"

See thread RT on oxidative stress and QD effects.
Thank you @NotTheMacAnon1 https://t.co/XlyXyiCS2H
— Found&Forgiven (@AshlieMC2) December 7, 2020

https://t.co/0ywQ1y5NDj

Pott found an association between exposure to soot and a high incidence of scrotal skin cancer in chimney sweeps. This cancer is now known as Pott's or chimney sweep cancer.

Coal contains trace amounts of naturally-occurring radioactive elements. The process of burning coal at coal-fired power plants, called combustion, creates wastes that contain small amounts of naturally-occurring radioactive material (NORM).

Fly ash particles (a major component of coal ash) can become lodged in the deepest part of your lungs, where they trigger asthma, inflammation and immunological reactions.

NotTheMacAnon
@NotTheMacAnon1

Transduction is the process by which foreign DNA is introduced into a cell by a virus or viral vector.

Viral vectors are tools commonly used by molecular biologists to deliver genetic material into cells.

Viruses have evolved?

specialized molecular mechanisms

to efficiently

transport their genomes

inside the cells they infect.

Delivery of genes, or other genetic material, by a vector is termed transduction and the infected cells are described as transduced.

A transducer is a device that converts energy from one form to another. Usually a transducer converts a signal in one form of energy to a signal in another.

NotTheMacAnon
@NotTheMacAnon1

Did the paedophiles create the virus?

I think so!

Is Joe Biden the paedophiles choice?

Jury’s out.

Scumbags

Lock them all up and f their vaccine.

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1/ 👋 Excited to share what we’ve been building at https://t.co/GOQJ7LjQ2t + we are going to tweetstorm our progress every week!

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4/ https://t.co/GOQJ7LjQ2t domain 🍻

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Here is a simple example of a machine learning model.

I put it together a long time ago, and it was very helpful! I sliced it apart a thousand times until things started to make sense.

It's TensorFlow and Keras.

If you are starting out, this may be a good puzzle to solve.

The goal of this model is to learn to multiply one-digit

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— Freddy Rojas Cama (@freddyrojascama) February 1, 2021

$Trond Bjor\xf8y$

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$Anu Satheesh \U0001f1ee\U0001f1f3$

Anu Satheesh 🇮🇳...
@AnuSatheesh5

#Guruvayur_Krishna_Bhakthi 🕉
#Guruvayur
#Storytime
Beautiful Story of Guruvayurappan

Poonathanam Namboothiri was a great devotee of Guruvayurappan. One day Poonthanam was going to Guruvayur Kshetram. It was night time and eventhough Namboothiri was tired he continued to walk

Suddenly some thieves came and blocked his way. Poonthanam cried for Shri Krishna to help. Thieves snatched all valuables from him, but Namboothiri holding his Bhaghavatam book called Shri Krishna to help. That time a man came in a horse back and fought with thieves and protected

Namboothiri. Poonthanam thanked Krishna for helping him from danger and said to the man that "Shri Krishna has send you here and I don't know how to thank you". The man smiled and told that he is Mangattachan, minister of samoodhiris. Poonthanam once again thanked him and

gave his ring to Mangattachan as a token of thanks and continued his journey. He reached Guruvayur early morning for Nirmalya Darshan. Temple poojari came near him and told that Guruvayurappan came in his dreams and asked to hand over the ring to poonthanam.

When he opened Kshetra Nada poonthanam was surprised to see his ring on Guruvayurappan, which he gifted to Mangattachan. He understood that it was Guruvayurappan who came as Mangattachan to protect him. This is how Bhagwan treat his devotees.

Hare Krishna
🙏🕉🙏

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“Don’t leave the church because of the people who hurt you. Nobody is perfect, only God”

I’ll explain why this comment is not only not helpful at all, but also very harmful.

1/

The comment assumes we can’t tell the difference between people and toxic theology, it assumes our issues are with a few people who are outliers and misrepresented God, and we just seem to think that’s the totality of divinity. Which makes us appear unintelligent and petty.

2/

But, that’s not the case at all. I didn’t leave because a few people hurt me in the name of God, in fact I stayed long enough to get hurt again, and again, and again, and again. Because it’s not a few bad apples hurting people in the name of God what we are dealing with.

3/

Instead we are talking about systemic abuse due to toxic theology that is taught as righteousness.

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4/

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5/

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$James \u270c\ufe0f$

James ✌️
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Starting a startup is hard. This thread will contain some key advice I think are particularly noteworthy:

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2. Don't build in a vacuum. You should build your product out in the open for the world to see. You will gain valuable feedback from users if you build publicly, and provide insights which ensure you are building a product users truly want. cc @rrhoover @sama

3. As a young founder, a massive weakness is age and the lack of credibility. Developing partnerships, trying to acquire customers. etc have all taken so much longer. In fact, when I mentioned my age, a few investors just walked away. cc @Jason

4. Work on what makes you feel excited. Working on something that you don't believe in will cause you to make rash product decisions, resulting in loss of user loyalty. @fredwilson

5. Take care of yourself. While doing the occasional code sprint can be incredibly useful, working 24/7 and disregarding your health just to build a great product is not a wise choice.

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'Tera mera rishta kya, hindu, hindu,hindutva' is a clear take on 'tera mera rishta kya,la ilaha illallah'. As much as Hindutva hates the monotheistic religions especially Islam, there's a strange wistfulness and subliminal need at display now, to BE that they hate. 1

Charlie Hebdo doesn’t come up as a cautionary tale now but rather 'why cant we be like that'?
Growing up, Hanuman was an adorable deity for us, who swallowed the sun, or who couldn’t figure out what was Sanjeevani booti so he picked up a whole mountain and came back with it. 2

Or he was loyal, admirable and when he cleaved his chest, you saw both Ram and Sita. Now we have a lot of “Angry Hanuman” stickers. Why is a cute childlike God angry? We don’t know. It's a convenient blank space where to paint all the angst of Hindu Khatre mein hain narrative. 3

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Shri is a prefix of respect in this case. Hinduism is being militarised. A woman/Sita has no place in it. Even the militaristic Goddess that is Durga has no place in this conception of neo-Hindu divinity, as evidenced by Dilip Mandal wondering where Durga came from. 5

Roger Grosse
@RogerGrosse

Important paper from Google on large batch optimization. They do impressively careful experiments measuring # iterations needed to achieve target validation error at various batch sizes. The main "surprise" is the lack of surprises. [thread]

https://t.co/7QIx5CFdfJ

The paper is a good example of lots of elements of good experimental design. They validate their metric by showing lots of variants give consistent results. They tune hyperparamters separately for each condition, check that optimum isn't at the endpoints, and measure sensitivity.

They have separate experiments where the hold fixed # iterations and # epochs, which (as they explain) measure very different things. They avoid confounds, such as batch norm's artificial dependence between batch size and regularization strength.

When the experiments are done carefully enough, the results are remarkably consistent between different datasets and architectures. Qualitatively, MNIST behaves just like ImageNet.

Importantly, they don't find any evidence for a "sharp/flat optima" effect whereby better optimization leads to worse final results. They have a good discussion of experimental artifacts/confounds in past papers where such effects were reported.