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🔗 History 🔗 Physics

Research concerning the relationship between the thermodynamic quantity entropy and the evolution of life began around the turn of the 20th century. In 1910, American historian Henry Adams printed and distributed to university libraries and history professors the small volume A Letter to American Teachers of History proposing a theory of history based on the second law of thermodynamics and on the principle of entropy.

The 1944 book What is Life? by Nobel-laureate physicist Erwin Schrödinger stimulated further research in the field. In his book, Schrödinger originally stated that life feeds on negative entropy, or negentropy as it is sometimes called, but in a later edition corrected himself in response to complaints and stated that the true source is free energy. More recent work has restricted the discussion to Gibbs free energy because biological processes on Earth normally occur at a constant temperature and pressure, such as in the atmosphere or at the bottom of the ocean, but not across both over short periods of time for individual organisms.

Ideas about the relationship between entropy and living organisms have inspired hypotheses and speculations in many contexts, including psychology, information theory, the origin of life, and the possibility of extraterrestrial life.

🔗 Human rights 🔗 Canada 🔗 Law 🔗 Canada/Canadian law

Section 33 of the Canadian Charter of Rights and Freedoms is part of the Constitution of Canada. It is commonly known as the notwithstanding clause (French: clause dérogatoire or clause nonobstant), sometimes referred to as the override power, and it allows Parliament or provincial legislatures to temporarily override sections 2 and 7–15 of the Charter.

🔗 Physics 🔗 Physics/relativity

In physics, there is a speculative hypothesis that, if there were a black hole with the same mass, charge and angular momentum as an electron, it would share other properties of the electron. Most notably, Brandon Carter showed in 1968 that the magnetic moment of such an object would match that of an electron. This is interesting because calculations ignoring special relativity and treating the electron as a small rotating sphere of charge give a magnetic moment roughly half the experimental value (see Gyromagnetic ratio).

However, Carter's calculations also show that a would-be black hole with these parameters would be "super-extremal". Thus, unlike a true black hole, this object would display a naked singularity, meaning a singularity in spacetime not hidden behind an event horizon. It would also give rise to closed timelike curves.

Standard quantum electrodynamics (QED), currently the most comprehensive theory of particles, treats the electron as a point particle. There is no evidence that the electron is a black hole (or naked singularity) or not. Furthermore, since the electron is quantum-mechanical in nature, any description purely in terms of general relativity is paradoxical until a better model based on understanding of quantum nature of blackholes and gravitational behaviour of quantum particles is developed by research. Hence, the idea of a black hole electron remains strictly hypothetical.

🔗 United States/U.S. Government 🔗 United States 🔗 Appalachia 🔗 National Archives 🔗 Tennessee 🔗 Energy 🔗 Alabama

The Tennessee Valley Authority (TVA) is a federally owned electric utility corporation in the United States. TVA's service area covers all of Tennessee, portions of Alabama, Mississippi, and Kentucky, and small areas of Georgia, North Carolina, and Virginia. While owned by the federal government, TVA receives no taxpayer funding and operates similarly to a private for-profit company. It is headquartered in Knoxville, Tennessee, and is the sixth-largest power supplier and largest public utility in the country.

The TVA was created by Congress in 1933 as part of President Franklin D. Roosevelt's New Deal. Its initial purpose was to provide navigation, flood control, electricity generation, fertilizer manufacturing, regional planning, and economic development to the Tennessee Valley, a region that had suffered from lack of infrastructure and even more extensive poverty during the Great Depression than other regions of the nation. TVA was envisioned both as a power supplier and a regional economic development agency that would work to help modernize the region's economy and society. It later evolved primarily into an electric utility. It was the first large regional planning agency of the U.S. federal government, and remains the largest.

Under the leadership of David E. Lilienthal, the TVA also became the global model for the United States' later efforts to help modernize agrarian societies in the developing world. The TVA historically has been documented as a success in its efforts to modernize the Tennessee Valley and helping to recruit new employment opportunities to the region. Historians have criticized its use of eminent domain and the displacement of over 125,000 Tennessee Valley residents to build the agency's infrastructure projects.

🔗 Architecture 🔗 Greece

The Tunnel of Eupalinos or Eupalinian aqueduct (Greek: Ευπαλίνιον όρυγμα, romanized: Efpalinion orygma) is a tunnel of 1,036 m (3,399 ft) length running through Mount Kastro in Samos, Greece, built in the 6th century BC to serve as an aqueduct. The tunnel is the second known tunnel in history which was excavated from both ends (Ancient Greek: ἀμφίστομον, romanized: amphistomon, "having two openings"), and the first with a geometry-based approach in doing so. Today it is a popular tourist attraction.

🔗 Physiology 🔗 Molecular Biology 🔗 Physiology/cell 🔗 Molecular Biology/Molecular and Cell Biology

Peto's paradox is an observation that at the species level, the incidence of cancer does not appear to correlate with the number of cells in an organism. For example, the incidence of cancer in humans is much higher than the incidence of cancer in whales, despite whales having more cells than humans. If the probability of carcinogenesis were constant across cells, one would expect whales to have a higher incidence of cancer than humans. Peto's paradox is named after English statistician and epidemiologist Richard Peto, who first observed the connection.

🔗 Human rights 🔗 Medicine 🔗 History of Science 🔗 Alabama 🔗 Science Policy 🔗 Nursing

The Tuskegee Study of Untreated Syphilis in the Negro Male (informally referred to as the Tuskegee Experiment or Tuskegee Syphilis Study) was a study conducted between 1932 and 1972 by the United States Public Health Service (PHS) and the Centers for Disease Control and Prevention (CDC) on a group of nearly 400 African American men with syphilis. The purpose of the study was to observe the effects of the disease when untreated, though by the end of the study medical advancements meant it was entirely treatable. The men were not informed of the nature of the experiment, and more than 100 died as a result.

The Public Health Service started the study in 1932 in collaboration with Tuskegee University (then the Tuskegee Institute), a historically Black college in Alabama. In the study, investigators enrolled a total of 600 impoverished African-American sharecroppers from Macon County, Alabama. Of these men, 399 had latent syphilis, with a control group of 201 men who were not infected. As an incentive for participation in the study, the men were promised free medical care. While the men were provided with both medical and mental care that they otherwise would not have received, they were deceived by the PHS, who never informed them of their syphilis diagnosis and provided disguised placebos, ineffective methods, and diagnostic procedures as treatment for "bad blood".

The men were initially told that the experiment was only going to last six months, but it was extended to 40 years. After funding for treatment was lost, the study was continued without informing the men that they would never be treated. None of the infected men were treated with penicillin despite the fact that, by 1947, the antibiotic was widely available and had become the standard treatment for syphilis.

The study continued, under numerous Public Health Service supervisors, until 1972, when a leak to the press resulted in its termination on November 16 of that year. By then, 28 patients had died directly from syphilis, 100 died from complications related to syphilis, 40 of the patients' wives were infected with syphilis, and 19 children were born with congenital syphilis.

The 40-year Tuskegee Study was a major violation of ethical standards and has been cited as "arguably the most infamous biomedical research study in U.S. history." Its revelation led to the 1979 Belmont Report and to the establishment of the Office for Human Research Protections (OHRP) and federal laws and regulations requiring institutional review boards for the protection of human subjects in studies. The OHRP manages this responsibility within the United States Department of Health and Human Services (HHS). Its revelation has also been an important cause of distrust in medical science and the US government amongst African Americans.

On May 16, 1997, President Bill Clinton formally apologized on behalf of the United States to victims of the study, calling it shameful and racist. "What was done cannot be undone, but we can end the silence," he said. "We can stop turning our heads away. We can look at you in the eye, and finally say, on behalf of the American people, what the United States government did was shameful and I am sorry."

🔗 Food and drink 🔗 Plants

Pepper X is a cultivar of Capsicum chili pepper bred by Ed Currie, creator of the Carolina Reaper. As of 2023, it is the world's hottest pepper.

🔗 Psychology

The need for cognition (NFC), in psychology, is a personality variable reflecting the extent to which individuals are inclined towards effortful cognitive activities.

Need for cognition has been variously defined as "a need to structure relevant situations in meaningful, integrated ways" and "a need to understand and make reasonable the experiential world". Higher NFC is associated with increased appreciation of debate, idea evaluation, and problem solving. Those with a high need for cognition may be inclined towards high elaboration. Those with a lower need for cognition may display opposite tendencies, and may process information more heuristically, often through low elaboration.

Need for cognition is closely related to the five factor model domain openness to experience, typical intellectual engagement, and epistemic curiosity (see below).

🔗 Computer science

Pearson hashing is a hash function designed for fast execution on processors with 8-bit registers. Given an input consisting of any number of bytes, it produces as output a single byte that is strongly dependent on every byte of the input. Its implementation requires only a few instructions, plus a 256-byte lookup table containing a permutation of the values 0 through 255.

This hash function is a CBC-MAC that uses an 8-bit substitution cipher implemented via the substitution table. An 8-bit cipher has negligible cryptographic security, so the Pearson hash function is not cryptographically strong, but it is useful for implementing hash tables or as a data integrity check code, for which purposes it offers these benefits:

• It is extremely simple.
• It executes quickly on resource-limited processors.
• There is no simple class of inputs for which collisions (identical outputs) are especially likely.
• Given a small, privileged set of inputs (e.g., reserved words for a compiler), the permutation table can be adjusted so that those inputs yield distinct hash values, producing what is called a perfect hash function.
• Two input strings differing by exactly one character never collide. E.g., applying the algorithm on the strings ABC and AEC will never produce the same value.

One of its drawbacks when compared with other hashing algorithms designed for 8-bit processors is the suggested 256 byte lookup table, which can be prohibitively large for a small microcontroller with a program memory size on the order of hundreds of bytes. A workaround to this is to use a simple permutation function instead of a table stored in program memory. However, using a too simple function, such as T[i] = 255-i, partly defeats the usability as a hash function as anagrams will result in the same hash value; using a too complex function, on the other hand, will affect speed negatively. Using a function rather than a table also allows extending the block size. Such functions naturally have to be bijective, like their table variants.

The algorithm can be described by the following pseudocode, which computes the hash of message C using the permutation table T:

algorithm pearson hashing is
    h := 0

    for each c in C loop
        h := T[ h xor c ]
    end loop

    return h

The hash variable (h) may be initialized differently, e.g. to the length of the data (C) modulo 256; this particular choice is used in the Python implementation example below.