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๐ Bullshit asymmetry principle
Bullshit (also bullcrap) is a common English expletive which may be shortened to the euphemism bull or the initialism B.S. In British English, "bollocks" is a comparable expletive. It is mostly a slang term and a profanity which means "nonsense", especially as a rebuke in response to communication or actions viewed as deceptive, misleading, disingenuous, unfair or false. As with many expletives, the term can be used as an interjection, or as many other parts of speech, and can carry a wide variety of meanings. A person who communicates nonsense on a given subject may be referred to as a "bullshit artist".
In philosophy and psychology of cognition the term "bullshit" is sometimes used to specifically refer to statements produced without particular concern of truth, to distinguish from a deliberate, manipulative lie intended to subvert the truth.
While the word is generally used in a deprecatory sense, it may imply a measure of respect for language skills or frivolity, among various other benign usages. In philosophy, Harry Frankfurt, among others, analyzed the concept of bullshit as related to, but distinct from, lying.
As an exclamation, "Bullshit!" conveys a measure of dissatisfaction with something or someone, but this usage need not be a comment on the truth of the matter.
Discussed on
- "Bullshit asymmetry principle" | 2018-10-10 | 85 Upvotes 37 Comments
๐ Mark Hofmann
Mark William Hofmann (born December 7, 1954) is an American counterfeiter, forger, and convicted murderer. Widely regarded as one of the most accomplished forgers in history, Hofmann is especially noted for his creation of documents related to the history of the Latter Day Saint movement. When his schemes began to unravel, he constructed bombs to murder two people in Salt Lake City, Utah.
Discussed on
- "Mark Hofmann" | 2018-10-09 | 65 Upvotes 22 Comments
๐ Hungry Tree
The Hungry Tree is a tree in the grounds of the King's Inns in Dublin, Republic of Ireland. An otherwise unremarkable specimen of the London plane, it has become known for having partially consumed a nearby park bench. It has become a tourist attraction and is frequently photographed. The Hungry Tree was the subject of a campaign by Green Party politician Ciarรกn Cuffe to ensure its preservation.
๐ Dvdisaster
dvdisaster is a computer program aimed to enhance data survivability on optical discs by creating error detection and correction data, which is used for data recovery. dvdisaster works exclusively at the image level. This program can be used either to generate Error-Correcting Code (ECC) data from an existing media or to augment an ISO image with ECC data prior to being written onto a medium. dvdisaster is free software available under the GNU General Public License.
๐ East German coffee crisis
The East German coffee crisis refers to shortages of coffee in the late 1970s in East Germany caused by a poor harvest and unstable commodity prices, severely limiting the government's ability to buy coffee on the world markets. As a consequence, the East German government increased its engagement in Africa and Asia, exporting weapons and equipment to coffee-producing nations.
Discussed on
- "East German coffee crisis" | 2018-10-08 | 91 Upvotes 16 Comments
๐ Lakes of Wada
In mathematics, the lakes of Wada (ๅ็ฐใฎๆน, Wada no mizuumi) are three disjoint connected open sets of the plane or open unit square with the counterintuitive property that they all have the same boundary. In other words, for any point selected on the boundary of one of the lakes, the other two lakes' boundaries also contain that point.
More than two sets with the same boundary are said to have the Wada property; examples include Wada basins in dynamical systems. This property is rare in real-world systems.
The lakes of Wada were introduced by Kunizล Yoneyamaย (1917,โpage 60), who credited the discovery to Takeo Wada. His construction is similar to the construction by Brouwer (1910) of an indecomposable continuum, and in fact it is possible for the common boundary of the three sets to be an indecomposable continuum.
Discussed on
- "Lakes of Wada" | 2018-10-07 | 66 Upvotes 15 Comments
๐ Oxford Electric Bell
The Oxford Electric Bell or Clarendon Dry Pile is an experimental electric bell that was set up in 1840 and which has run nearly continuously ever since. It was one of the first pieces purchased for a collection of apparatus by clergyman and physicist Robert Walker. It is located in a corridor adjacent to the foyer of the Clarendon Laboratory at the University of Oxford, England, and is still ringing, though inaudibly due to being behind two layers of glass.
Discussed on
- "Oxford Electric Bell" | 2018-10-06 | 109 Upvotes 12 Comments
- "Oxford Electric Bell" | 2014-06-02 | 106 Upvotes 60 Comments
๐ Asynchronous (Clockless) CPU
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.
Discussed on
- "Asynchronous (Clockless) CPU" | 2018-10-05 | 168 Upvotes 60 Comments
๐ Pearson Hashing
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 messageย C using the permutation tableย T:
algorithm pearson hashing is
hย := 0
for each c in C loop
hย := 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.
๐ Unidirectional Network
A unidirectional network (also referred to as a unidirectional gateway or data diode) is a network appliance or device that allows data to travel in only one direction. Data diodes can be found most commonly in high security environments, such as defense, where they serve as connections between two or more networks of differing security classifications. Given the rise of industrial IoT and digitization, this technology can now be found at the industrial control level for such facilities as nuclear power plants, power generation and safety critical systems like railway networks.
After years of development the use of data diodes have increased creating two variations:
- Data diode: Network appliance or device allowing raw data to travel only in one direction, used in guaranteeing information security or protection of critical digital systems, such as industrial control systems, from inbound cyber attacks.
- Unidirectional gateway: Combination of hardware and software running in proxy computers in the source and destination networks. The hardware, a data diode, enforces physical unidirectionality and the software replicates databases and emulates protocol servers to handle bi-directional communication. The unidirectional gateway is capable of transferring multiple protocols and data types simultaneously. It contains a broader range of cybersecurity features like, secure boot, certificate management, data integrity, forward error correction (FEC), secure communication via TLS, among others. A unique characteristic is that data is transferred deterministically (to predetermined locations) with a protocol "break" that allows the data to be transferred through the data diode.
Data diodes are commonly found in high security military and government environments, and are now becoming widely spread in sectors like oil & gas, water/wastewater, airplanes (between flight control units and in-flight entertainment systems), manufacturing and cloud connectivity for industrial IoT. New regulations have increased demand and with increased capacity, major technology vendors have lowered the cost of the core technology.
Discussed on
- "Unidirectional Network" | 2018-10-04 | 15 Upvotes 5 Comments