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Penicillin The pH and the levels of nitrogen, lysine, phosphate, and oxygen of the batches must also be carefully controlled. The biotechnological method of directed evolution has been applied to produce by mutation a large number of "Penicillium" strains. These techniques include error-prone PCR, DNA shuffling, ITCHY, and strand-overlap PCR. Semisynthetic penicillins are prepared starting from the penicillin nucleus 6-APA. Overall, there are three main and important steps to the biosynthesis of penicillin G (benzylpenicillin). | https://en.wikipedia.org/wiki?curid=23312 | 154,288 |
Synthetic genomics Soon after the discovery of restriction endonucleases and ligases, the field of genetics began using these molecular tools to assemble artificial sequences from smaller fragments of synthetic or naturally-occurring DNA. The advantage in using the recombinatory approach as opposed to continual DNA synthesis stems from the inverse relationship that exists between synthetic DNA length and percent purity of that synthetic length. In other words, as you synthesize longer sequences, the number of error-containing clones increases due to the inherent error rates of current technologies. Although recombinant DNA technology is more commonly used in the construction of fusion proteins and plasmids, several techniques with larger capacities have emerged, allowing for the construction of entire genomes. Polymerase cycling assembly (PCA) uses a series of oligonucleotides (or oligos), approximately 40 to 60 nucleotides long, that altogether constitute both strands of the DNA being synthesized. These oligos are designed such that a single oligo from one strand contains a length of approximately 20 nucleotides at each end that is complementary to sequences of two different oligos on the opposite strand, thereby creating regions of overlap. The entire set is processed through cycles of: (a) hybridization at 60 °C; (b) elongation via Taq polymerase and a standard ligase; and (c) denaturation at 95 °C, forming progressively longer contiguous strands and ultimately resulting in the final genome | https://en.wikipedia.org/wiki?curid=11330015 | 193,569 |
Safe operating area ) will carry a lower current density, tending to even out any temperature variation and prevent hot spots. Recently, MOSFETs with very high transconductance, optimised for switching operation, have become available. When operated in linear mode, especially at high drain-source voltages and low drain currents, the gate-source voltage tends to be very close to the threshold voltage. Unfortunately the threshold voltage decreases as temperature increases, so that if there are any slight temperature variations across the chip, then the hotter regions will tend to carry more current than the cooler regions when Vgs is very close to Vth. This can lead to thermal runaway and the destruction of the MOSFET even when it is operating within its Vds, Id and Pd ratings. Some (usually expensive) MOSFETs are specified for operation in the linear region and include DC SOA diagrams, e.g. IXYS IXTK8N150L. Transistors require some time to turn off, due to effects such as minority carrier storage time and capacitance. While turning off, they may be damaged depending on how the load responds (especially with poorly snubbed inductive loads). The reverse bias safe operating area (or RBSOA) is the SOA during the brief time before turning the device into the off state—during the short time when the base current bias is reversed. As long as the collector voltage and collector current stay within the RBSOA during the entire turnoff, the transistor will be undamaged | https://en.wikipedia.org/wiki?curid=976730 | 389,772 |
Tariff Thus, the damage done could not possibly have exceeded 1 or 2 percent of world GDP — nowhere near the 17 percent falloff seen during the Great Depression... The inescapable conclusion: contrary to public perception, Smoot-Hawley did not cause, or even significantly deepen, the Great Depression," Nobel laureate Maurice Allais argued: 'First, most of the trade contraction occurred between January 1930 and July 1932, before most protectionist measures were introduced, except for the limited measures applied by the United States in the summer of 1930. It was therefore the collapse of international liquidity that caused the contraction of trade[8], not customs tariffs'. Russia adopted more protectionist trade measures in 2013 than any other country, making it the world leader in protectionism. It alone introduced 20% of protectionist measures worldwide and one-third of measures in the G20 countries. Russia's protectionist policies include tariff measures, import restrictions, sanitary measures, and direct subsidies to local companies. For example, the state supported several economic sectors such as agriculture, space, automotive, electronics, chemistry, and energy. In recent years, the policy of import substitution due to tariffs, i.e. the replacement of imported products by domestic products, has been considered a success because it has enabled Russia to increase its domestic production and save several billion dollars | https://en.wikipedia.org/wiki?curid=55551 | 509,853 |
Robert Lusch In 2009 the AMA awarded him its IOSIG Lifetime Achievement Award, and in 2010 he was the recipient of the AMA/Sheth Foundation Award for long-standing contributions to marketing literature. In February 2013 Lusch was presented the AMA/Irwin/McGraw-Hill Distinguished Marketing Educator Award. | https://en.wikipedia.org/wiki?curid=24788943 | 452,049 |
1999 Aggie Bonfire collapse On October 28, 2008, Texas A&M settled the final lawsuit filed against them by the victims and their families. The university agreed to pay $2.1 million and promised that if the bonfire returned to campus that "engineering oversight" would be provided. The final lawsuit, filed against two companies that provided crane operators and cranes for the bonfire, was settled in April 2014. News coverage: Websites in favor of the bonfire continuing: | https://en.wikipedia.org/wiki?curid=55796803 | 342,934 |
Cairo Citadel More significantly in the long run, Qalawun was the first to create elite regiments of mamluks (soldiers of slave origin) who resided in the various towers of the Citadel, which earned them the name "Burji" Mamluks (Mamluks of the Tower). It was these cohorts of mamluks who would eventually dominate the sultanate during the Burji Mamluk period. Sultan al-Ashraf Khalil built a "qa'a" (reception hall) in 1291-1292, referred to as the "Qa'a al-Ashrafiyya." Its remains were excavated in the late 20th century and are still visible today, just west of the present-day gate called "Bab al-'Alam" (Gate of the Flag), across the terrace from the current Police Museum. The remains indicate that the walls of the hall were decorated with multi-coloured marble paneling along the lower walls (a dado), above which was a small frieze of marble mosaics with mother-of-pearl and other marble reliefs, and above all this were panels of glass mosaics with scenes of trees and palaces which are reminiscent of the mosaics of the Ummayyad Mosque and Mausoleum of Baybars in Damascus. (During excavations the mosaics were removed for study and restoration.) The hall also had a central octagonal fountain of marble and the floor was paved with marble mosaics arranged in geometric patterns. It was one of the few structures in this area which al-Nasir Muhammad did not destroy but instead re-used for various purposes, and in the Burji Mamluk period it seems to have replaced the "Dar al-Niyaba" as the palace of the vice-regent | https://en.wikipedia.org/wiki?curid=2814371 | 317,503 |
Dynamic range compression Compression is often applied in audio systems for restaurants, retail, and similar public environments that play background music at a relatively low volume and need it compressed, not just to keep the volume fairly constant, but also to make quiet parts of the music audible over ambient noise. Compression can increase average output gain of a power amplifier by 50 to 100% with a reduced dynamic range. For paging and evacuation systems, this adds clarity under noisy circumstances and saves on the number of amplifiers required. Compression is often used in music production to make performances more consistent in dynamic range so that they "sit" in the mix of other instruments better and maintain consistent attention from the listener. Vocal performances in rock music or pop music are usually compressed to improve clarity and to make them stand out from the surrounding instruments. Compression can also be used on instrument sounds to create effects not primarily focused on boosting loudness. For instance, drum and cymbal sounds tend to decay quickly, but a compressor can make the sound appear to have a more sustained tail. Guitar sounds are often compressed to produce a fuller, more sustained sound. Most devices capable of compressing audio dynamics can also be used to reduce the volume of one audio source when another audio source reaches a certain level; this is called side-chaining | https://en.wikipedia.org/wiki?curid=262733 | 227,215 |
Long non-coding RNA Similar models have been proposed in mammals, where strong epigenetic mechanisms are thought to underlie the embryonic expression profiles of the Hox genes that persist throughout human development. Indeed, the human Hox genes are associated with hundreds of ncRNAs that are sequentially expressed along both the spatial and temporal axes of human development and define chromatin domains of differential histone methylation and RNA polymerase accessibility. One ncRNA, termed HOTAIR, that originates from the HOXC locus represses transcription across 40 kb of the HOXD locus by altering chromatin trimethylation state. HOTAIR is thought to achieve this by directing the action of Polycomb chromatin remodeling complexes in trans to govern the cells' epigenetic state and subsequent gene expression. Components of the Polycomb complex, including Suz12, EZH2 and EED, contain RNA binding domains that may potentially bind HOTAIR and probably other similar ncRNAs. This example nicely illustrates a broader theme whereby ncRNAs recruit the function of a generic suite of chromatin modifying proteins to specific genomic loci, underscoring the complexity of recently published genomic maps. Indeed, the prevalence of long ncRNAs associated with protein coding genes may contribute to localised patterns of chromatin modifications that regulate gene expression during development | https://en.wikipedia.org/wiki?curid=16770101 | 297,571 |
Reynolds stress Thus, by analogy, the is sometimes thought of as consisting of an isotropic pressure part, termed the turbulent pressure, and an off-diagonal part which may be thought of as an effective turbulent viscosity. In fact, while much effort has been expended in developing good models for the in a fluid, as a practical matter, when solving the fluid equations using computational fluid dynamics, often the simplest turbulence models prove the most effective. One class of models, closely related to the concept of turbulent viscosity, are the k-epsilon turbulence models, based upon coupled transport equations for the turbulent energy density formula_37 (similar to the turbulent pressure, i.e. the trace of the Reynolds stress) and the turbulent dissipation rate formula_38. Typically, the average is formally defined as an ensemble average as in statistical ensemble theory. However, as a practical matter, the average may also be thought of as a spatial average over some length scale, or a temporal average. Note that, while formally the connection between such averages is justified in equilibrium statistical mechanics by the ergodic theorem, the statistical mechanics of hydrodynamic turbulence is currently far from understood. In fact, the at any given point in a turbulent fluid is somewhat subject to interpretation, depending upon how one defines the average. | https://en.wikipedia.org/wiki?curid=1852294 | 202,685 |
Founder effect Around 1814, a small group of British colonists founded a settlement on Tristan da Cunha, a group of small islands in the Atlantic Ocean, midway between Africa and South America. One of the early colonists apparently carried a rare, recessive allele for retinitis pigmentosa, a progressive form of blindness that afflicts homozygous individuals. As late as 1961, the majority of the genes in the gene pool on Tristan were still derived from 15 original ancestors; as a consequence of the inbreeding, of 232 people tested in 1961, four were suffering from retinitis pigmentosa. This represents a prevalence of 1 in 58, compared with a worldwide prevalence of around 1 in 4,000. The abnormally high rate of twin births in Cândido Godói could be explained by the founder effect. | https://en.wikipedia.org/wiki?curid=392309 | 174,348 |
Roof cleaning based Asphalt Roofing Manufactureres' Association specifies the use of a bleach cleaning solution, without the use of a pressure washer, to remove algae from a roof. ARMA discourages the use of a pressure washer, a flat-surface cleaner or any other mechanical device to clean a roof. Safe, effective soft washing cannot be achieved with a pressure washer, as the Venturi device (downstreaming) cannot achieve sufficient strength solution to kill the organisms, cleaning the roof. Use of different tips on the pressure washer, so that it drops the pressure down to around or less, relies on the pressure of the equipment, and not the chemicals, to clean the roof. Never use a pressure washer as this may damage the roof. devices exist that may minimize the spread of airborne radioactive materials (in contaminated areas) and other harmful materials, such as asbestos. Specialized robots have been designed to facilitate cleaning roofs. | https://en.wikipedia.org/wiki?curid=28553041 | 362,646 |
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