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🔗 Textile Arts

The Jacquard machine (French: [ʒakaʁ]) is a device fitted to a power loom that simplifies the process of manufacturing textiles with such complex patterns as brocade, damask and matelassé. It was invented by Joseph Marie Jacquard in 1804, based on earlier inventions by the Frenchmen Basile Bouchon (1725), Jean Baptiste Falcon (1728), and Jacques Vaucanson (1740). The machine was controlled by a "chain of cards"; a number of punched cards laced together into a continuous sequence. Multiple rows of holes were punched on each card, with one complete card corresponding to one row of the design. Several such paper cards, generally white in color, can be seen in the images below. Chains, like Bouchon's earlier use of paper tape, allowed sequences of any length to be constructed, not limited by the size of a card.

Both the Jacquard process and the necessary loom attachment are named after their inventor. This mechanism is probably one of the most important weaving inventions as Jacquard shedding made possible the automatic production of unlimited varieties of pattern weaving. The term "Jacquard" is not specific or limited to any particular loom, but rather refers to the added control mechanism that automates the patterning. The process can also be used for patterned knitwear and machine-knitted textiles, such as jerseys.

This use of replaceable punched cards to control a sequence of operations is considered an important step in the history of computing hardware.

🔗 France 🔗 Military history 🔗 Military history/Military science, technology, and theory 🔗 Military history/Weaponry 🔗 Military history/World War I 🔗 Military history/French military history 🔗 Military history/Military land vehicles 🔗 Military history/European military history

The Boirault machine (French: Appareil Boirault), was an early French experimental landship, designed in 1914 and built in early 1915. It has been considered as "another interesting ancestor of the tank", and described as a "rhomboid-shaped skeleton tank without armour, with single overhead track". Ultimately, the machine was deemed impractical and was nicknamed Diplodocus militaris. It preceded the design and development of the English Little Willie tank by six months.

🔗 History of Science 🔗 Transhumanism

The Drexler–Smalley debate on molecular nanotechnology was a public dispute between K. Eric Drexler, the originator of the conceptual basis of molecular nanotechnology, and Richard Smalley, a recipient of the 1996 Nobel prize in Chemistry for the discovery of the nanomaterial buckminsterfullerene. The dispute was about the feasibility of constructing molecular assemblers, which are molecular machines which could robotically assemble molecular materials and devices by manipulating individual atoms or molecules. The concept of molecular assemblers was central to Drexler's conception of molecular nanotechnology, but Smalley argued that fundamental physical principles would prevent them from ever being possible. The two also traded accusations that the other's conception of nanotechnology was harmful to public perception of the field and threatened continued public support for nanotechnology research.

The debate was carried out from 2001 to 2003 through a series of published articles and open letters. It began with a 2001 article by Smalley in Scientific American, which was followed by a rebuttal published by Drexler and coworkers later that year, and two open letters by Drexler in early 2003. The debate was concluded in late 2003 in a "Point–Counterpoint" feature in Chemical & Engineering News in which both parties participated.

The debate has been often cited in the history of nanotechnology due to the fame of its participants and its commentary on both the technical and social aspects of nanotechnology. It has also been widely criticized for its adversarial tone, with Drexler accusing Smalley of publicly misrepresenting his work, and Smalley accusing Drexler of failing to understand basic science, causing commentators to go so far as to characterize the tone of the debate as similar to "a pissing match" and "reminiscent of [a] Saturday Night Live sketch".

🔗 Computing 🔗 Computing/Software 🔗 Computing/Computer science 🔗 Cryptography 🔗 Cryptography/Computer science

In cryptography and computer science, a hash tree or Merkle tree is a tree in which every leaf node is labelled with the cryptographic hash of a data block, and every non-leaf node is labelled with the cryptographic hash of the labels of its child nodes. Hash trees allow efficient and secure verification of the contents of large data structures. Hash trees are a generalization of hash lists and hash chains.

Demonstrating that a leaf node is a part of a given binary hash tree requires computing a number of hashes proportional to the logarithm of the number of leaf nodes of the tree; this contrasts with hash lists, where the number is proportional to the number of leaf nodes itself.

The concept of hash trees is named after Ralph Merkle, who patented it in 1979.

🔗 Philosophy 🔗 Skepticism 🔗 Psychology 🔗 Philosophy/Contemporary philosophy 🔗 Philosophy/Philosophy of mind 🔗 Alternative Views 🔗 Neuroscience

Bicameralism (the condition of being divided into "two-chambers") is a hypothesis in psychology that argues that the human mind once operated in a state in which cognitive functions were divided between one part of the brain which appears to be "speaking", and a second part which listens and obeys—a bicameral mind. The term was coined by Julian Jaynes, who presented the idea in his 1976 book The Origin of Consciousness in the Breakdown of the Bicameral Mind, wherein he made the case that a bicameral mentality was the normal and ubiquitous state of the human mind as recently as 3,000 years ago, near the end of the Mediterranean bronze age.

🔗 United States 🔗 Books 🔗 Science Fiction

The Astronautilia (Czech: Hvězdoplavba; full title in Greek: Ποιητοῦ ἀδήλου ΑΣΤΡΟΝΑΥΤΙΛΙΑ ἢ ἡ Μικροοδύσσεια ἡ κοσμική; i.e. "An unknown poet's Starvoyage, or the Cosmic Micro-Odyssey") is the magnum opus, written in 1994 under the hellenised pseudonym Ἰωάννης Πυρεῖα, of Czech poet and writer Jan Křesadlo, one of the most unusual works of twentieth-century Czech literature. It was published shortly after his death, as a commemorative first edition.

While no full English translation exists as yet, there is a sample chapter translation online, and a German translation of the fully transcribed and annotated Greek text is in preparation.

🔗 Psychology 🔗 Neuroscience 🔗 Physiology

The effects of stress on memory include interference with a person's capacity to encode memory and the ability to retrieve information. Stimuli, like stress, improved memory when it was related to learning the subject. During times of stress, the body reacts by secreting stress hormones into the bloodstream. Stress can cause acute and chronic changes in certain brain areas which can cause long-term damage. Over-secretion of stress hormones most frequently impairs long-term delayed recall memory, but can enhance short-term, immediate recall memory. This enhancement is particularly relative in emotional memory. In particular, the hippocampus, prefrontal cortex and the amygdala are affected. One class of stress hormone responsible for negatively affecting long-term, delayed recall memory is the glucocorticoids (GCs), the most notable of which is cortisol. Glucocorticoids facilitate and impair the actions of stress in the brain memory process. Cortisol is a known biomarker for stress. Under normal circumstances, the hippocampus regulates the production of cortisol through negative feedback because it has many receptors that are sensitive to these stress hormones. However, an excess of cortisol can impair the ability of the hippocampus to both encode and recall memories. These stress hormones are also hindering the hippocampus from receiving enough energy by diverting glucose levels to surrounding muscles.

Stress affects many memory functions and cognitive functioning of the brain. There are different levels of stress and the high levels can be intrinsic or extrinsic. Intrinsic stress level is triggered by a cognitive challenge whereas extrinsic can be triggered by a condition not related to a cognitive task. Intrinsic stress can be acutely and chronically experienced by a person. The varying effects of stress on performance or stress hormones are often compared to or known as "inverted-u" which induce areas in learning, memory and plasticity. Chronic stress can affect the brain structure and cognition.

Studies considered the effects of both intrinsic and extrinsic stress on memory functions, using for both of them Pavlovian conditioning and spatial learning. In regard to intrinsic memory functions, the study evaluated how stress affected memory functions that was triggered by a learning challenge. In regard to extrinsic stress, the study focused on stress that was not related to cognitive task but was elicited by other situations. The results determined that intrinsic stress was facilitated by memory consolidation process and extrinsic stress was determined to be heterogeneous in regard to memory consolidation. Researchers found that high stress conditions were a good representative of the effect that extrinsic stress can cause on memory functioning. It was also proven that extrinsic stress does affect spatial learning whereas acute extrinsic stress does not.

🔗 Philosophy 🔗 Philosophy/Logic 🔗 Philosophy/Ethics

The paradox of hedonism, also called the pleasure paradox, refers to the practical difficulties encountered in the pursuit of pleasure. For the hedonist, constant pleasure-seeking may not yield the most actual pleasure or happiness in the long run—or even in the short run, when consciously pursuing pleasure interferes with experiencing it.

The utilitarian philosopher Henry Sidgwick was first to note in The Methods of Ethics that the paradox of hedonism is that pleasure cannot be acquired directly. Variations on this theme appear in the realms of ethics, philosophy, psychology, and economics.

🔗 California 🔗 California/San Francisco Bay Area 🔗 History 🔗 Viruses

The Anti-Mask League of San Francisco was an organization formed to protest an ordinance which required people in San Francisco, California to wear masks during the 1918 influenza pandemic. The ordinance it protested lasted less than one month before being repealed. Due to the short period of the league's existence, its exact membership is difficult to determine; however, an estimated 4,000–5,000 citizens showed up to a meeting to protest the second ordinance in January 1919. Opposition to similar ordinances during the COVID-19 pandemic in the United States led to renewed interest in, and comparisons with, the Anti-Mask League.