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🔗 Physics

A Bessel beam is a wave whose amplitude is described by a Bessel function of the first kind. Electromagnetic, acoustic, gravitational, and matter waves can all be in the form of Bessel beams. A true Bessel beam is non-diffractive. This means that as it propagates, it does not diffract and spread out; this is in contrast to the usual behavior of light (or sound), which spreads out after being focused down to a small spot. Bessel beams are also self-healing, meaning that the beam can be partially obstructed at one point, but will re-form at a point further down the beam axis.

As with a plane wave, a true Bessel beam cannot be created, as it is unbounded and would require an infinite amount of energy. Reasonably good approximations can be made, however, and these are important in many optical applications because they exhibit little or no diffraction over a limited distance. Approximations to Bessel beams are made in practice either by focusing a Gaussian beam with an axicon lens to generate a Bessel–Gauss beam, by using axisymmetric diffraction gratings, or by placing a narrow annular aperture in the far field. High order Bessel beams can be generated by spiral diffraction gratings.

🔗 Animal anatomy 🔗 Marine life 🔗 Limnology and Oceanography

Spicules are structural elements found in most sponges. The meshing of many spicules serves as the sponge's skeleton and thus it provides structural support and potentially defense against predators.

Sponge spicules are made of calcium carbonate or silica. Large spicules visible to the naked eye are referred to as megascleres, while smaller, microscopic ones are termed microscleres. The composition, size, and shape of spicules are major characters in sponge systematics and taxonomy.

🔗 Internet 🔗 Cryptography 🔗 Cryptography/Computer science

k-anonymity is a property possessed by certain anonymized data. The concept of k-anonymity was first introduced by Latanya Sweeney and Pierangela Samarati in a paper published in 1998 as an attempt to solve the problem: "Given person-specific field-structured data, produce a release of the data with scientific guarantees that the individuals who are the subjects of the data cannot be re-identified while the data remain practically useful." A release of data is said to have the k-anonymity property if the information for each person contained in the release cannot be distinguished from at least ${\displaystyle k-1}$ individuals whose information also appear in the release.

K-anonymity received widespread media coverage in 2018 when British computer scientist Junade Ali used the property alongside cryptographic hashing to create a communication protocol to anonymously verify if a password was leaked without disclosing the searched password. This protocol was implemented as a public API in Troy Hunt's Have I Been Pwned? service and is consumed by multiple services including password managers and browser extensions. This approach was later replicated by Google's Password Checkup feature.

🔗 United States 🔗 Politics 🔗 LGBT studies 🔗 Sexology and sexuality 🔗 Politics/American politics 🔗 Donald Trump 🔗 Conservatism 🔗 Pornography

Project 2025 is a plan to reshape the executive branch of the U.S. federal government in the event of a Republican victory in the 2024 U.S. presidential election. Established in 2022, the project seeks to recruit tens of thousands of conservatives to Washington, D.C., to replace existing federal civil service workers it characterizes as the "deep state", to further the objectives of the next Republican president. Although participants in the project cannot promote a specific presidential candidate, many have close ties to Donald Trump and the Trump 2024 presidential campaign. The plan would perform a swift takeover of the entire executive branch under a maximalist version of the unitary executive theory — a theory proposing the president of the United States has absolute power over the executive branch — upon inauguration.

The development of the plan is led by the The Heritage Foundation, an American conservative think tank, in collaboration with over 100 partners including Turning Point USA led by Charlie Kirk; the Conservative Partnership Institute including former Trump Chief of Staff Mark Meadows as senior partner; the Center for Renewing America led by former Trump-appointee Office of Management and Budget Director Russell Vought; and America First Legal led by former Trump Senior Advisor Stephen Miller.

Project 2025 envisions widespread changes across the entire government, particularly with regard to economic and social policy and the role of the federal government and federal agencies. The plan proposes slashing U.S. Department of Justice (DOJ) funding, dismantling the FBI and the Department of Homeland Security, gutting environmental and climate change regulations to favor fossil fuel production, and eliminating the cabinet Departments of Education and Commerce. Citing an anonymous source, The Washington Post reported Project 2025 includes immediately invoking the Insurrection Act of 1807 to deploy the military for domestic law enforcement and directing the DOJ to pursue Trump adversaries. Project Director Paul Dans, a former Trump administration official, said in September 2023 that Project 2025 is "systematically preparing to march into office and bring a new army, aligned, trained, and essentially weaponized conservatives ready to do battle against the deep state."

Project 2025 consists largely of a book of policy recommendations titled Mandate for Leadership: The Conservative Promise and an accompanying personnel database open for submissions. There is also an online course called the Presidential Administration Academy, and a guide to developing transition plans. Reactions to the plan included variously describing it as authoritarian, an attempt by Trump to become a dictator, and a path leading the United States towards autocracy, with several experts in law criticizing it for violating current constitutional laws that would undermine the rule of law and the separation of powers. Additionally, some conservatives and Republicans also criticized the plan, for example in relation to climate change. The Mandate states that "freedom is defined by God, not man."

🔗 Biography 🔗 Law 🔗 Computer Security 🔗 Computer Security/Computing 🔗 Biography/science and academia 🔗 Florida

Jonathan Joseph James (December 12, 1983 – May 18, 2008) was an American hacker who was the first juvenile incarcerated for cybercrime in the United States. The South Florida native was 15 years old at the time of the first offense and 16 years old on the date of his sentencing. He died at his Pinecrest, Florida home on May 18, 2008, of a self-inflicted gunshot wound.

🔗 Germany

The Bielefeld conspiracy (German: Bielefeldverschwörung or Bielefeld-Verschwörung, pronounced [ˈbiːləfɛltfɛɐ̯ˌʃvøːʁʊŋ]) is a satire of conspiracy theories that claims that the city of Bielefeld, Germany, does not exist, but is an illusion propagated by various forces. First posted on the German Usenet in 1994, the conspiracy has since been mentioned in the city's marketing, and referenced by Chancellor Angela Merkel.

🔗 Computing

In computer science, the ostrich algorithm is a strategy of ignoring potential problems on the basis that they may be exceedingly rare. It is named for the ostrich effect which is defined as "to stick one's head in the sand and pretend there is no problem". It is used when it is more cost-effective to allow the problem to occur than to attempt its prevention.

🔗 Physics 🔗 Astronomy

Entropic gravity, also known as emergent gravity, is a theory in modern physics that describes gravity as an entropic force—a force with macro-scale homogeneity but which is subject to quantum-level disorder—and not a fundamental interaction. The theory, based on string theory, black hole physics, and quantum information theory, describes gravity as an emergent phenomenon that springs from the quantum entanglement of small bits of spacetime information. As such, entropic gravity is said to abide by the second law of thermodynamics under which the entropy of a physical system tends to increase over time.

At its simplest, the theory holds that when gravity becomes vanishingly weak—levels seen only at interstellar distances—it diverges from its classically understood nature and its strength begins to decay linearly with distance from a mass.

Entropic gravity provides the underlying framework to explain Modified Newtonian Dynamics, or MOND, which holds that at a gravitational acceleration threshold of approximately 1.2×10⁻¹⁰ m/s², gravitational strength begins to vary inversely (linearly) with distance from a mass rather than the normal inverse-square law of the distance. This is an exceedingly low threshold, measuring only 12 trillionths gravity's strength at earth's surface; an object dropped from a height of one meter would fall for 36 hours were earth's gravity this weak. It is also 3,000 times less than exists at the point where Voyager 1 crossed our solar system's heliopause and entered interstellar space.

The theory claims to be consistent with both the macro-level observations of Newtonian gravity as well as Einstein's theory of general relativity and its gravitational distortion of spacetime. Importantly, the theory also explains (without invoking the existence of dark matter and its accompanying math featuring new free parameters that are tweaked to obtain the desired outcome) why galactic rotation curves differ from the profile expected with visible matter.

The theory of entropic gravity posits that what has been interpreted as unobserved dark matter is the product of quantum effects that can be regarded as a form of positive dark energy that lifts the vacuum energy of space from its ground state value. A central tenet of the theory is that the positive dark energy leads to a thermal-volume law contribution to entropy that overtakes the area law of anti-de Sitter space precisely at the cosmological horizon.

The theory has been controversial within the physics community but has sparked research and experiments to test its validity.

🔗 Statistics

Survivorship bias or survival bias is the logical error of concentrating on the people or things that made it past some selection process and overlooking those that did not, typically because of their lack of visibility. This can lead to false conclusions in several different ways. It is a form of selection bias.

Survivorship bias can lead to overly optimistic beliefs because failures are ignored, such as when companies that no longer exist are excluded from analyses of financial performance. It can also lead to the false belief that the successes in a group have some special property, rather than just coincidence (correlation proves causality). For example, if three of the five students with the best college grades went to the same high school, that can lead one to believe that the high school must offer an excellent education. This could be true, but the question cannot be answered without looking at the grades of all the other students from that high school, not just the ones who "survived" the top-five selection process. Another example of a distinct mode of survivorship bias would be thinking that an incident was not as dangerous as it was because everyone you communicate with afterwards survived. Even if you knew that some people are dead, they wouldn't have their voice to add to the conversation, leading to bias in the conversation.

🔗 Maps 🔗 Turkey 🔗 Paranormal

The Piri Reis map is a world map compiled in 1513 by the Ottoman admiral and cartographer Piri Reis (pronounced [piːˈɾiː ɾeis]). Approximately one third of the map survives; it shows the western coasts of Europe and North Africa and the coast of Brazil with reasonable accuracy. Various Atlantic islands, including the Azores and Canary Islands, are depicted, as is the mythical island of Antillia and possibly Japan.

The map's historical importance lies in its demonstration of the extent of global exploration of the New World by approximately 1510, and in its claim to have used a map of Christopher Columbus, otherwise lost, as a source. Piri also stated that he had used ten Arab sources and four Indian maps sourced from the Portuguese. More recently, the map has been the focus of claims for the pre-modern exploration of the Antarctic coast.

The Piri Reis map is in the Library of the Topkapı Palace in Istanbul, Turkey, but is not usually on display to the public.