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🔗 Cryptography 🔗 Cryptography/Computer science

The MD6 Message-Digest Algorithm is a cryptographic hash function. It uses a Merkle tree-like structure to allow for immense parallel computation of hashes for very long inputs. Authors claim a performance of 28 cycles per byte for MD6-256 on an Intel Core 2 Duo and provable resistance against differential cryptanalysis. The source code of the reference implementation was released under MIT license.

Speeds in excess of 1 GB/s have been reported to be possible for long messages on 16-core CPU architecture.

In December 2008, Douglas Held of Fortify Software discovered a buffer overflow in the original MD6 hash algorithm's reference implementation. This error was later made public by Ron Rivest on 19 February 2009, with a release of a corrected reference implementation in advance of the Fortify Report.

MD6 was submitted to the NIST SHA-3 competition. However, on July 1, 2009, Rivest posted a comment at NIST that MD6 is not yet ready to be a candidate for SHA-3 because of speed issues, a "gap in the proof that the submitted version of MD6 is resistant to differential attacks", and an inability to supply such a proof for a faster reduced-round version, although Rivest also stated at the MD6 website that it is not withdrawn formally. MD6 did not advance to the second round of the SHA-3 competition. In September 2011, a paper presenting an improved proof that MD6 and faster reduced-round versions are resistant to differential attacks was posted to the MD6 website.

🔗 Computing 🔗 Electronics 🔗 Electrical engineering

An asynchronous circuit, or self-timed circuit, is a sequential digital logic circuit which is not governed by a clock circuit or global clock signal. Instead it often uses signals that indicate completion of instructions and operations, specified by simple data transfer protocols. This type of circuit is contrasted with synchronous circuits, in which changes to the signal values in the circuit are triggered by repetitive pulses called a clock signal. Most digital devices today use synchronous circuits. However asynchronous circuits have the potential to be faster, and may also have advantages in lower power consumption, lower electromagnetic interference, and better modularity in large systems. Asynchronous circuits are an active area of research in digital logic design.

🔗 Environment 🔗 India 🔗 Birds

Nine species of vulture can be found living in India, but most are now in danger of extinction after a rapid and major population collapse in recent decades. In the early 1980s, three species of Gyps vultures (the white-rumped vulture, the long-billed vulture and the slender-billed vulture) had a combined estimated population of 40 million in South Asia, but as of 2017, the total population numbered only 19,000 (6,000, 12,000, and 1,000 respectively). With a catastrophic loss of over 99.95% of all the vultures in South Asia, the Indian vulture crisis represents the sharpest decline of any animal known to man in the same number of years. A major contributing factor in declining populations of vultures is believed to be widespread use of drugs such as diclofenac, once commonly used as a livestock anti-inflammatory drug. Veterinary usage of diclofenac has been banned in India since 2006. The IUCN Red Data Book has listed Gyps bengalensis as "critically endangered". In winter 2012, 56 vultures in three species (Eurasian griffon, cinereous vulture, Egyptian vulture) and 10 steppe eagles were found dead at a dumping site in Jorbeer, Rajasthan. Six Eurasian griffons were found dead in May 2013 due to dehydration and wing weakness. The area has been declared as a conserved forest area, but the carcass dumping site is not part of the protected area.

The dramatic vulture decline observed across India presents a range of ecological threats, by influencing the numbers and distribution of other scavenging species. Increased feral dog populations have been reported all over India, posing many associated disease risks such as rabies to humans and wildlife. India already accounts for a very high incidence of rabies cases, and an absolute shortage of quality anti-rabies vaccine in rural areas can aggravate the problem even further. Similarly, increased crow populations at carcass sites near settlement areas pose a risk of infections to poultry, domesticated birds, and humans. Prevalence and concentration of diclofenac residues in ungulate carcasses is important for India's threatened vulture populations. A small proportion (< 0.8%) of ungulate carcasses containing lethal levels of diclofenac is enough to cause the observed rapid decline of vultures population. (Bohra D L)

Vultures previously played an important role in public sanitation in India and their disappearance has resulted in a number of problems, and as such numerous conservation schemes are in place to assist in the recovery of vulture populations.

🔗 Mathematics 🔗 Statistics

The secretary problem is a problem that demonstrates a scenario involving optimal stopping theory. The problem has been studied extensively in the fields of applied probability, statistics, and decision theory. It is also known as the marriage problem, the sultan's dowry problem, the fussy suitor problem, the googol game, and the best choice problem.

The basic form of the problem is the following: imagine an administrator who wants to hire the best secretary out of ${\displaystyle n}$ rankable applicants for a position. The applicants are interviewed one by one in random order. A decision about each particular applicant is to be made immediately after the interview. Once rejected, an applicant cannot be recalled. During the interview, the administrator gains information sufficient to rank the applicant among all applicants interviewed so far, but is unaware of the quality of yet unseen applicants. The question is about the optimal strategy (stopping rule) to maximize the probability of selecting the best applicant. If the decision can be deferred to the end, this can be solved by the simple maximum selection algorithm of tracking the running maximum (and who achieved it), and selecting the overall maximum at the end. The difficulty is that the decision must be made immediately.

The shortest rigorous proof known so far is provided by the odds algorithm (Bruss 2000). It implies that the optimal win probability is always at least ${\displaystyle 1/e}$ (where e is the base of the natural logarithm), and that the latter holds even in a much greater generality (2003). The optimal stopping rule prescribes always rejecting the first ${\displaystyle \sim n/e}$ applicants that are interviewed and then stopping at the first applicant who is better than every applicant interviewed so far (or continuing to the last applicant if this never occurs). Sometimes this strategy is called the ${\displaystyle 1/e}$ stopping rule, because the probability of stopping at the best applicant with this strategy is about ${\displaystyle 1/e}$ already for moderate values of ${\displaystyle n}$. One reason why the secretary problem has received so much attention is that the optimal policy for the problem (the stopping rule) is simple and selects the single best candidate about 37% of the time, irrespective of whether there are 100 or 100 million applicants.

🔗 Spaceflight

NASA Extreme Environment Mission Operations, or NEEMO, is a NASA analog mission that sends groups of astronauts, engineers and scientists to live in Aquarius underwater laboratory, the world's only undersea research station, for up to three weeks at a time in preparation for future space exploration.

Aquarius is an underwater habitat 3.5 miles (5.6 km) off Key Largo, Florida, in the Florida Keys National Marine Sanctuary. It is deployed on the ocean floor next to deep coral reefs 62 feet (19 m) below the surface.

NASA has used it since 2001 for a series of space exploration simulation missions, usually lasting 7 to 14 days, with space research mainly conducted by international astronauts. The mission had cost about 500 million U.S. dollars. The crew members are called aquanauts (as they live underwater at depth pressure for a period equal to or greater than 24 continuous hours without returning to the surface), and they perform EVAs in the underwater environment. A technique known as saturation diving allows the aquanauts to live and work underwater for days or weeks at a time. After twenty four hours underwater at any depth, the human body becomes saturated with dissolved gas. With saturation diving, divers can accurately predict exactly how much time they need to decompress before returning to the surface. This information limits the risk of decompression sickness. By living in the Aquarius habitat and working at the same depth on the ocean floor, NEEMO crews are able to remain underwater for the duration of their mission.

For NASA, the Aquarius habitat and its surroundings provide a convincing analog for space exploration. Much like space, the undersea world is a hostile, alien place for humans to live. NEEMO crew members experience some of the same challenges there that they would on a distant asteroid, planet (i.e. Mars) or Moon. During NEEMO missions, the aquanauts are able to simulate living on a spacecraft and test spacewalk techniques for future space missions. Working in space and underwater environments requires extensive planning and sophisticated equipment. The underwater condition has the additional benefit of allowing NASA to "weight" the aquanauts to simulate different gravity environments.

Until 2012, Aquarius was owned by the National Oceanic and Atmospheric Administration (NOAA) and operated by the National Undersea Research Center (NURC) at the University of North Carolina–Wilmington as a marine biology study base.

Since 2013, Aquarius is owned by Florida International University (FIU). As part of the FIU Marine Education and Research Initiative, the Medina Aquarius Program is dedicated to the study and preservation of marine ecosystems worldwide and is enhancing the scope and impact of FIU on research, educational outreach, technology development, and professional training. At the heart of the program is the Aquarius Reef Base.

🔗 Internet 🔗 Computing 🔗 Computing/Networking

Nagle's algorithm is a means of improving the efficiency of TCP/IP networks by reducing the number of packets that need to be sent over the network. It was defined by John Nagle while working for Ford Aerospace. It was published in 1984 as a Request for Comments (RFC) with title Congestion Control in IP/TCP Internetworks in RFC 896.

The RFC describes what he called the "small-packet problem", where an application repeatedly emits data in small chunks, frequently only 1 byte in size. Since TCP packets have a 40-byte header (20 bytes for TCP, 20 bytes for IPv4), this results in a 41-byte packet for 1 byte of useful information, a huge overhead. This situation often occurs in Telnet sessions, where most keypresses generate a single byte of data that is transmitted immediately. Worse, over slow links, many such packets can be in transit at the same time, potentially leading to congestion collapse.

Nagle's algorithm works by combining a number of small outgoing messages and sending them all at once. Specifically, as long as there is a sent packet for which the sender has received no acknowledgment, the sender should keep buffering its output until it has a full packet's worth of output, thus allowing output to be sent all at once.

🔗 Biography 🔗 Mathematics 🔗 Australia 🔗 Biography/science and academia

Terence Chi-Shen Tao (born 17 July 1975) is an Australian-American mathematician who has worked in various areas of mathematics. He currently focuses on harmonic analysis, partial differential equations, algebraic combinatorics, arithmetic combinatorics, geometric combinatorics, probability theory, compressed sensing and analytic number theory. As of 2015, he holds the James and Carol Collins chair in mathematics at the University of California, Los Angeles.

Tao was a recipient of the 2006 Fields Medal and the 2014 Breakthrough Prize in Mathematics. He is also a 2006 MacArthur Fellow. Tao has been the author or co-author of 275 research papers.

Tao is the second mathematician of Han Chinese descent to win the Fields medal after Shing-Tung Yau, and the first Australian citizen to win the medal.

🔗 United States 🔗 Politics 🔗 Women's History 🔗 United States/U.S. presidential elections 🔗 United States/District of Columbia 🔗 Current events 🔗 Joe Biden 🔗 Women in Red

The inauguration of Joe Biden as the 46th President of the United States took place on January 20, 2021, before noon (EST), marking the commencement of the four-year term of Joe Biden as president and Kamala Harris as vice president. The inaugural ceremony took place on the West Front of the United States Capitol in Washington, D.C. and was the 59th presidential inauguration. Biden took the presidential oath of office, before which Harris took the vice presidential oath of office.

The inauguration took place amidst extraordinary political, public health, economic, and national security crises, including outgoing President Donald Trump's attempts to overturn the 2020 United States presidential election, which incited a storming of the Capitol, Trump's unprecedented second impeachment, and a threat of widespread civil unrest, which stimulated a nationwide law enforcement response. Festivities were sharply curtailed by efforts to prevent the spread of COVID-19 and mitigate the potential for violence near the Capitol. The live audience was limited to members of the 117th United States Congress and, for each, one guest of their choosing, resembling a State of the Union address. Public health measures such as mandatory face coverings, testing, temperature checks, and social distancing were used to protect participants in the ceremony.

"America United" and "Our Determined Democracy: Forging a More Perfect Union"—a reference to the Preamble to the United States Constitution—served as the inaugural themes.

🔗 Computer Security 🔗 Computer Security/Computing 🔗 Project-independent assessment

Slopsquatting is a type of cybersquatting. It is the practice of registering a non-existent software package name that a large language model (LLM) may hallucinate in its output, whereby someone unknowingly may copy-paste and install the software package without realizing it is fake. Attempting to install a non-existent package should result in an error, but some have exploited this for their gain in the form of typosquatting.

The name is a portmanteau of "slop" and "typosquatting".

🔗 Computing 🔗 Computer Security 🔗 Computer Security/Computing 🔗 Computing/Software

In information security and programming, a buffer overflow, or buffer overrun, is an anomaly where a program, while writing data to a buffer, overruns the buffer's boundary and overwrites adjacent memory locations.

Buffers are areas of memory set aside to hold data, often while moving it from one section of a program to another, or between programs. Buffer overflows can often be triggered by malformed inputs; if one assumes all inputs will be smaller than a certain size and the buffer is created to be that size, then an anomalous transaction that produces more data could cause it to write past the end of the buffer. If this overwrites adjacent data or executable code, this may result in erratic program behavior, including memory access errors, incorrect results, and crashes.

Exploiting the behavior of a buffer overflow is a well-known security exploit. On many systems, the memory layout of a program, or the system as a whole, is well defined. By sending in data designed to cause a buffer overflow, it is possible to write into areas known to hold executable code and replace it with malicious code, or to selectively overwrite data pertaining to the program's state, therefore causing behavior that was not intended by the original programmer. Buffers are widespread in operating system (OS) code, so it is possible to make attacks that perform privilege escalation and gain unlimited access to the computer's resources. The famed Morris worm in 1988 used this as one of its attack techniques.

Programming languages commonly associated with buffer overflows include C and C++, which provide no built-in protection against accessing or overwriting data in any part of memory and do not automatically check that data written to an array (the built-in buffer type) is within the boundaries of that array. Bounds checking can prevent buffer overflows, but requires additional code and processing time. Modern operating systems use a variety of techniques to combat malicious buffer overflows, notably by randomizing the layout of memory, or deliberately leaving space between buffers and looking for actions that write into those areas ("canaries").