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🔗 The Species Problem
The species problem is the set of questions that arises when biologists attempt to define what a species is. Such a definition is called a species concept; there are at least 26 recognized species concepts. A species concept that works well for sexually reproducing organisms such as birds is useless for species that reproduce asexually, such as bacteria. The scientific study of the species problem has been called microtaxonomy.
One common, but sometimes difficult, question is how best to decide which species an organism belongs to, because reproductively isolated groups may not be readily recognizable, and cryptic species may be present. There is a continuum from reproductive isolation with no interbreeding, to panmixis, unlimited interbreeding. Populations can move forward or backwards along this continuum, at any point meeting the criteria for one or another species concept, and failing others.
Many of the debates on species touch on philosophical issues, such as nominalism and realism, and on issues of language and cognition.
The current meaning of the phrase "species problem" is quite different from what Charles Darwin and others meant by it during the 19th and early 20th centuries. For Darwin, the species problem was the question of how new species arose. Darwin was however one of the first people to question how well-defined species are, given that they constantly change.
Discussed on
- "The Species Problem" | 2015-11-10 | 27 Upvotes 2 Comments
🔗 Netpbm format
Netpbm is an open-source package of graphics programs and a programming library. It is used mainly in the Unix world, where one can find it included in all major open-source operating system distributions, but also works on Microsoft Windows, macOS, and other operating systems.
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- "Netpbm format" | 2015-11-07 | 29 Upvotes 23 Comments
🔗 Russian Domesticated Red Fox
The Russian domesticated red fox is a form of the wild red fox (Vulpes vulpes) which has been domesticated to an extent, under laboratory conditions. They are the result of an experiment which was designed to demonstrate the power of selective breeding to transform species, as described by Charles Darwin in On the Origin of Species. The experiment was purposely designed to replicate the process that had produced dogs from wolves, by recording the changes in foxes, when in each generation only the most tame foxes were allowed to breed. In short order, the descendant foxes became tamer and more dog-like in their behavior.
The program was started in 1959 in the Soviet Union by zoologist Dmitry Belyayev and it has been in continuous operation since. Today, the experiment is under the supervision of Lyudmila Trut, in Russia, at the Institute of Cytology and Genetics in Novosibirsk.
Discussed on
- "Russian Domesticated Red Fox" | 2015-11-06 | 96 Upvotes 30 Comments
🔗 Foetry.com
Foetry.com, sometimes referred to as just Foetry, was a website that attempted to identify fraudulent and unethical practices in poetry contests. It was active from April 1, 2004 until May 18, 2007.
Discussed on
- "Foetry.com" | 2015-11-03 | 31 Upvotes 4 Comments
🔗 Refal programming language
Refal ("[of] Recursive functions' algorithmic language") "is functional programming language oriented toward symbolic computations", including "string processing, language translation, [and] artificial intelligence". It is one of the oldest members of this family, first conceived of in 1966 as a theoretical tool, with the first implementation appearing in 1968. Refal was intended to combine mathematical simplicity with practicality for writing large and sophisticated programs.
One of the first functional programming languages to do so, and unlike Lisp of its time, Refal is based on pattern matching. Its pattern matching works in conjunction with term rewriting.
The basic data structure of Lisp and Prolog is a linear list built by cons operation in a sequential manner, thus with O(n) access to list's nth element. Refal's lists are built and scanned from both ends, with pattern matching working for nested lists as well as the top-level one. In effect, the basic data structure of Refal is a tree rather than a list. This gives freedom and convenience in creating data structures while using only mathematically simple control mechanisms of pattern matching and substitution.
Refal also includes a feature called the freezer to support efficient partial evaluation.
Refal can be applied to the processing and transformation of tree structures, similarly to XSLT.
Discussed on
- "Refal programming language" | 2015-11-01 | 33 Upvotes 12 Comments
- "Refal programming language" | 2009-12-18 | 31 Upvotes 3 Comments
🔗 Wire wrap
Wire wrap was invented to wire telephone crossbar switches, and later adapted to construct electronic circuit boards. Electronic components mounted on an insulating board are interconnected by lengths of insulated wire run between their terminals, with the connections made by wrapping several turns of uninsulated sections of the wire around a component lead or a socket pin.
Wires can be wrapped by hand or by machine, and can be hand-modified afterwards. It was popular for large-scale manufacturing in the 1960s and early 1970s, and continues today to be used for short runs and prototypes. The method eliminates the design and fabrication of a printed circuit board. Wire wrapping is unusual among other prototyping technologies since it allows for complex assemblies to be produced by automated equipment, but then easily repaired or modified by hand.
Wire wrap construction can produce assemblies which are more reliable than printed circuits: connections are less prone to fail due to vibration or physical stresses on the base board, and the lack of solder precludes soldering faults such as corrosion, cold joints and dry joints. The connections themselves are firmer and have lower electrical resistance due to cold welding of the wire to the terminal post at the corners.
Wire wrap was used for assembly of high frequency prototypes and small production runs, including gigahertz microwave circuits and supercomputers. It is unique among automated prototyping techniques in that wire lengths can be exactly controlled, and twisted pairs or magnetically shielded twisted quads can be routed together.
Wire wrap construction became popular around 1960 in circuit board manufacturing, and use has now sharply declined. Surface-mount technology has made the technique much less useful than in previous decades. Solder-less breadboards and the decreasing cost of professionally made PCBs have nearly eliminated this technology.
Discussed on
- "Wire wrap" | 2015-10-31 | 16 Upvotes 10 Comments
🔗 BitTorrent's DHT
Mainline DHT is the name given to the Kademlia-based Distributed Hash Table (DHT) used by BitTorrent clients to find peers via the BitTorrent protocol. The idea of utilizing a DHT for distributed tracking was first implemented in Azureus 2.3.0.0 (now known as Vuze) in May 2005, from which it gained significant popularity. Unrelated but similarly timed BitTorrent, Inc. released their own similar DHT into their client, called Mainline DHT and thus popularized the use of distributed tracking in the BitTorrent Protocol. Measurement shows by 2013 users of Mainline DHT is from 10 million to 25 million, with a daily churn of at least 10 million.
Discussed on
- "BitTorrent's DHT" | 2015-10-29 | 97 Upvotes 33 Comments
🔗 Gotthard Base Tunnel
The Gotthard Base Tunnel (GBT; German: Gotthard-Basistunnel, Italian: Galleria di base del San Gottardo, Romansh: Tunnel da basa dal Son Gottard) is a railway tunnel through the Alps in Switzerland. It opened on 1 June 2016, and full service began on 11 December 2016. With a route length of 57.09 km (35.5 mi), it is the world's longest railway and deepest traffic tunnel and the first flat, low-level route through the Alps. It lies at the heart of the Gotthard axis and constitutes the third tunnel connecting the cantons of Uri and Ticino, after the Gotthard Tunnel and the Gotthard Road Tunnel.
The link consists of two single-track tunnels connecting Erstfeld (Uri) with Bodio (Ticino) and passing below Sedrun (Graubünden). It is part of the New Railway Link through the Alps (NRLA) project, which also includes the Ceneri Base Tunnel further south (scheduled to open late 2020) and the Lötschberg Base Tunnel on the other main north–south axis. It is referred to as a "base tunnel" since it bypasses most of the existing Gotthard railway line, a winding mountain route opened in 1882 across the Saint-Gotthard Massif, which was operating at its capacity before the opening of the GBT. The new base tunnel establishes a direct route usable by high-speed rail and heavy freight trains.
The main purpose of the Gotthard Base Tunnel is to increase local transport capacity through the Alpine barrier, especially for freight, notably on the Rotterdam–Basel–Genoa corridor, and more specifically to shift freight volumes from trucks to freight trains. This both significantly reduces the danger of fatal road crashes involving trucks, and reduces the environmental damage caused by heavy trucks. The tunnel provides a faster connection between the canton of Ticino and the rest of Switzerland, as well as between northern and southern Europe, cutting the Basel/Zürich–Lugano–Milan journey time for passenger trains by one hour (and from Lucerne to Bellinzona by 45 minutes).
After 64 percent of Swiss voters accepted the NRLA project in a 1992 referendum, first preparatory and exploratory work began in 1996. The official start of construction began on 4 November 1999 at Amsteg. Drilling operations in the eastern tunnel were completed on 15 October 2010 in a breakthrough ceremony broadcast live on Swiss TV, and in the western tunnel on 23 March 2011. The tunnel's constructor, AlpTransit Gotthard AG, originally planned to hand over the tunnel to Swiss Federal Railways (SBB CFF FFS) in operating condition in December 2016 but, on 4 February 2014, the handover date was changed to 5 June 2016 with the start of an 850-day opening countdown calendar on the AlpTransit homepage. As of 1998, the total projected cost of the project was CHF 6.323 billion; as of December 2015, the final cost is projected as CHF 9.560 billion. Nine people died during construction.
Discussed on
- "Gotthard Base Tunnel" | 2015-10-28 | 97 Upvotes 48 Comments
🔗 R v Dudley and Stephens – British murder case of 1884
R v Dudley and Stephens (1884) 14 QBD 273 DC is a leading English criminal case which established a precedent throughout the common law world that necessity is not a defence to a charge of murder. It concerned survival cannibalism following a shipwreck and its purported justification on the basis of a custom of the sea. It marked the culmination of a long history of attempts by the law, in the face of public opinion sympathetic to castaways, to outlaw the custom and it became something of a cause célèbre in Victorian Britain.
Dudley and Stephens were shipwrecked along with two other men. When one of them, the cabin boy Richard Parker, fell into a coma, Dudley and Stephens decided to kill him for food.
🔗 Arne Næss: Recommendations for Public Debate
Arne Dekke Eide Næss ( AR-nə NESS; Norwegian: [ˈnɛsː]; 27 January 1912 – 12 January 2009) was a Norwegian philosopher who coined the term "deep ecology" and was an important intellectual and inspirational figure within the environmental movement of the late twentieth century. Næss cited Rachel Carson's 1962 book Silent Spring as being a key influence in his vision of deep ecology. Næss combined his ecological vision with Gandhian nonviolence and on several occasions participated in direct action.
Næss averred that while western environmental groups of the early post-war period had raised public awareness of the environmental issues of the time, they had largely failed to have insight into and address what he argued were the underlying cultural and philosophical background to these problems. Naess believed that the environmental crisis of the twentieth century had arisen due to certain unspoken philosophical presuppositions and attitudes within modern western developed societies which remained unacknowledged.
He thereby distinguished between what he called deep and shallow ecological thinking. In contrast to the prevailing utilitarian pragmatism of western businesses and governments, he advocated that a true understanding of nature would give rise to a point of view that appreciates the value of biological diversity, understanding that each living thing is dependent on the existence of other creatures in the complex web of interrelationships that is the natural world.
Discussed on
- "Arne Næss: Recommendations for Public Debate" | 2015-10-23 | 22 Upvotes 4 Comments