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π Agbogbloshie, the world's largest e-waste dump
Agbogbloshie is a nickname of a commercial district on the Korle Lagoon of the Odaw River, near the center of Accra, Ghana's capital city. Near the slum called "Old Fadama", the Agbogbloshie site became known as a destination for externally generated automobile and electronic scrap collected from mostly the western world. It was alleged to be at the center of a legal and illegal exportation network for the environmental dumping of electronic waste (e-waste) from industrialized nations. The Basel Action Network, a small NGO based in Seattle, has referred to Agbogbloshie as a "digital dumping ground", where they allege millions of tons of e-waste are processed each year.
However, repeated international studies have failed to confirm the allegations, which have been labelled an "e-waste hoax" by international reuse advocate WR3A. The most exhaustive study of the trade in used electronics in Nigeria, funded by UNEP and Basel Convention, revealed that from 540 000 tonnes of informally processed waste electronics, 52% of the material was recovered.
According to statistics from the World Bank, in large cities like Accra and Lagos the majority of households have owned televisions and computers for decades. The UN Report "Where are WEEE in Africa" (2012) disclosed that the majority of used electronics found in African dumps had not in fact been recently imported as scrap, but originated from these African cities. Agbogbloshie is situated on the banks of the Korle Lagoon, northwest of Accra's Central Business District. Roughly 40,000 Ghanaians inhabit the area, most of whom are migrants from rural areas. Due to its harsh living conditions and rampant crime, the area is nicknamed "Sodom and Gomorrah".
The Basel Convention prevents the transfrontier shipment of hazardous waste from developed to less developed countries. However, the Convention specifically allows export for reuse and repair under Annex Ix, B1110. While numerous international press reports have made reference to allegations that the majority of exports to Ghana are dumped, research by the US International Trade Commission found little evidence of unprocessed e-waste being shipped to Africa from the United States, a finding corroborated by the United Nations Environment Programme, MIT, Memorial University, Arizona State University, and other research. In 2013, the original source of the allegation blaming foreign dumping for the material found in Agbogbloshie recanted, or rather stated it had never made the claim that 80% of US e-waste is exported.
Whether domestically generated by residents of Ghana or imported, concern remains over methods of waste processing - especially burning - which emit toxic chemicals into the air, land and water. Exposure is especially hazardous to children, as these toxins are known to inhibit the development of the reproductive system, the nervous system, and especially the brain. Concerns about human health and the environment of Agbogbloshie continue to be raised as the area remains heavily polluted. In the 2000s, the Ghanaian government, with new funding and loans, implemented the Korle Lagoon Ecological Restoration Project (KLERP), an environmental remediation and restoration project that will address the pollution problem by dredging the lagoon and Odaw canal to improve drainage and flooding into the ocean.
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- "Agbogbloshie, the world's largest e-waste dump" | 2015-03-03 | 107 Upvotes 51 Comments
π Confocal microscopy
Confocal microscopy, most frequently confocal laser scanning microscopy (CLSM) or laser scanning confocal microscopy (LSCM), is an optical imaging technique for increasing optical resolution and contrast of a micrograph by means of using a spatial pinhole to block out-of-focus light in image formation. Capturing multiple two-dimensional images at different depths in a sample enables the reconstruction of three-dimensional structures (a process known as optical sectioning) within an object. This technique is used extensively in the scientific and industrial communities and typical applications are in life sciences, semiconductor inspection and materials science.
Light travels through the sample under a conventional microscope as far into the specimen as it can penetrate, while a confocal microscope only focuses a smaller beam of light at one narrow depth level at a time. The CLSM achieves a controlled and highly limited depth of field.
Discussed on
- "Confocal microscopy" | 2024-01-22 | 44 Upvotes 19 Comments
π Cpuid: EAX=8FFFFFFFh: AMD Easter Egg
In the x86 architecture, the CPUID instruction (identified by a CPUID
opcode) is a processor supplementary instruction (its name derived from CPU IDentification) allowing software to discover details of the processor. It was introduced by Intel in 1993 with the launch of the Pentium and SL-enhanced 486 processors.
A program can use the CPUID
to determine processor type and whether features such as MMX/SSE are implemented.
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- "Cpuid: EAX=8FFFFFFFh: AMD Easter Egg" | 2021-11-26 | 24 Upvotes 7 Comments
π Starlight (Interstellar Probe)
Project Starlight is a research project of the University of California, Santa Barbara to develop a fleet of laser beam-propelled interstellar probes and sending them to a star neighboring the Solar System, potentially Alpha Centauri. The project aims to send organisms on board the probe.
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- "Starlight (Interstellar Probe)" | 2022-10-09 | 76 Upvotes 135 Comments
π The Prisoner
The Prisoner is a 1967 British television series about an unnamed British intelligence agent who is abducted and imprisoned in a mysterious coastal village, where his captors designate him as Number Six and try to find out why he abruptly resigned from his job. Patrick McGoohan played the lead role as Number Six. The series was created by McGoohan with possible contributions from George Markstein. Episode plots have elements of science fiction, allegory, and psychological drama, as well as spy fiction. It was produced by Everyman Films for distribution by Lew Grade's ITC Entertainment.
A single series of 17 episodes was filmed between September 1966 and January 1968, with exterior location filming in Portmeirion, Wales. Interior scenes were filmed at MGM-British Studios in Borehamwood, north of London. The series was first broadcast in Canada beginning on 5 September 1967, in the UK on 29 September 1967, and in the US on 1 June 1968. Although the show was sold as a thriller in the mould of the previous series starring McGoohan, Danger Man, its combination of 1960s countercultural themes and surrealistic setting had a far-reaching influence on science fiction and fantasy TV programming, and on narrative popular culture in general. Since its initial screening, the series has developed a cult following.
A six-part TV miniseries remake aired on the US cable channel AMC in November 2009. In 2016, Big Finish Productions reinterpreted the series as an audio drama.
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- "The Prisoner" | 2022-12-14 | 20 Upvotes 10 Comments
π Swarm intelligence
Swarm intelligence (SI) is the collective behavior of decentralized, self-organized systems, natural or artificial. The concept is employed in work on artificial intelligence. The expression was introduced by Gerardo Beni and Jing Wang in 1989, in the context of cellular robotic systems.
SI systems consist typically of a population of simple agents or boids interacting locally with one another and with their environment. The inspiration often comes from nature, especially biological systems. The agents follow very simple rules, and although there is no centralized control structure dictating how individual agents should behave, local, and to a certain degree random, interactions between such agents lead to the emergence of "intelligent" global behavior, unknown to the individual agents. Examples of swarm intelligence in natural systems include ant colonies, bird flocking, hawks hunting, animal herding, bacterial growth, fish schooling and microbial intelligence.
The application of swarm principles to robots is called swarm robotics, while 'swarm intelligence' refers to the more general set of algorithms. 'Swarm prediction' has been used in the context of forecasting problems. Similar approaches to those proposed for swarm robotics are considered for genetically modified organisms in synthetic collective intelligence.
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- "Swarm intelligence" | 2011-01-22 | 37 Upvotes 11 Comments
π Five Minute Rule
In computer science, the five-minute rule is a rule of thumb for deciding whether a data item should be kept in memory, or stored on disk and read back into memory when required. It was first formulated by Jim Gray and Gianfranco Putzolu in 1985, and then subsequently revised in 1997 and 2007 to reflect changes in the relative cost and performance of memory and persistent storage.
The rule is as follows:
The 5-minute random rule: cache randomly accessed disk pages that are re-used every 5 minutes or less.
Gray also issued a counterpart one-minute rule for sequential access:
The 1-minute rule: cache sequentially accessed disk pages that are re-used every 1 minute or less.
Although the 5-minute rule was invented in the realm of databases, it has also been applied elsewhere, for example, in Network File System cache capacity planning.
The original 5-minute rule was derived from the following cost-benefit computation:
- BreakEvenIntervalinSeconds = (PagesPerMBofRAM / AccessesPerSecondPerDisk) Γ (PricePerDiskDrive / PricePerMBofRAM)
Applying it to 2007 data yields approximately a 90-minutes interval for magnetic-disk-to-DRAM caching, 15 minutes for SSD-to-DRAM caching and 2β1β4 hours for disk-to-SSD caching. The disk-to-DRAM interval was thus a bit short of what Gray and Putzolu anticipated in 1987 as the "five-hour rule" was going to be in 2007 for RAM and disks.
According to calculations by NetApp engineer David Dale as reported in The Register, the figures for disc-to-DRAM caching in 2008 were as follows: "The 50KB page break-even was five minutes, the 4KB one was one hour and the 1KB one was five hours. There needed to be a 50-fold increase in page size to cache for break-even at five minutes." Regarding disk-to-SSD caching in 2010, the same source reported that "A 250KB page break even with SLC was five minutes, but five hours with a 4KB page size. It was five minutes with a 625KB page size with MLC flash and 13 hours with a 4KB MLC page size."
In 2000, Gray and Shenoy applied a similar calculation for web page caching and concluded that a browser should "cache web pages if there is any chance they will be re-referenced within their lifetime."
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- "Five Minute Rule" | 2015-10-06 | 51 Upvotes 12 Comments
π A photo on Wikipedia can ruin your life
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- "A photo on Wikipedia can ruin your life" | 2021-11-06 | 219 Upvotes 148 Comments
π Wikipedia Now with Dark Mode
A light-on-dark color scheme (dark mode, night mode) is available to Wikipedia's smartphone apps and website (for users using the default skins) since July 2024.
In addition to this there is a gadget on English Wikipedia, and various volunteer-written CSS files that allow customization for logged-in users.
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- "Wikipedia Now with Dark Mode" | 2024-07-27 | 11 Upvotes 2 Comments
π Electro Gyrocator
The Electro Gyro-Cator was claimed to be the world's first automated commercially available automotive navigation system. It was co-developed by Honda, Alpine, and Stanley Electric Co..
Unlike most navigation systems of today, it did not use GPS Satellites to maintain its position and discern movement of the vehicle. Rather, it was an Inertial navigation system, because it contained a helium gas gyroscope that could detect both rotation and movement. A special servo gear was also attached to the transmission housing to feed information to the Gyro-Cator to help maintain position, map speed and distance traveled.
Transparent maps were placed inside the unit and it would scroll them past a 6 inch monochrome CRT illuminated screen as the car traveled along. The monitor would indicate by a series of circles (or cross hairs) on the screen to show the vehicle's current location or display lines for path of travel. A marking pen was also included to help make personal indicators on the map if needed. Adjustments could be made to change the display scale, position, rotation, brightness, and contrast. In its only year of production in 1981, it was announced as an option on that year's Honda Accord and Honda Vigor, but at Β₯300,000 ($2,746 USD), it was almost a quarter of the value of the car. It is not clear how many units were actually sold to customers as a "dealer option". A patent for gyroscope design was introduced to the US in design patent D274332.
Documented weight for the unit was roughly 20Β lb (9Β kg). A display unit, with a cutaway of the Gyroscope, is currently shown at the Honda Collection Hall at Twin Ring Motegi, Japan.
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- "Electro Gyrocator" | 2023-01-28 | 101 Upvotes 57 Comments