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Paramecium is a genus of eukaryotic, unicellular ciliates, commonly studied as a representative of the ciliate group. Paramecia are widespread in freshwater, brackish, and marine environments and are often very abundant in stagnant basins and ponds. Because some species are readily cultivated and easily induced to conjugate and divide, it has been widely used in classrooms and laboratories to study biological processes. Its usefulness as a model organism has caused one ciliate researcher to characterize it as the "white rat" of the phylum Ciliophora.
USS Bunker Hill was one of 24 Essex-class aircraft carriers built during World War II for the United States Navy. The ship was named for the Battle of Bunker Hill in the American Revolutionary War. Commissioned in May 1943 and sent to the Pacific Theater of Operations, the ship participated in battles in the Southwest Pacific, Central Pacific and the drive toward Japan through Iwo Jima, Okinawa, and air raids on the Japanese homeland.
A sanitary sewer is an underground pipe or tunnel system for transporting sewage from houses and commercial buildings to a sewage treatment plant or disposal. Sanitary sewers are a type of gravity sewer and are part of an overall system called a "sewage system" or sewerage. Sanitary sewers serving industrial areas may also carry industrial wastewater. In municipalities served by sanitary sewers, separate storm drains may convey surface runoff directly to surface waters. An advantage of sanitary sewer systems is that they avoid combined sewer overflows. Sanitary sewers are typically much smaller in diameter than combined sewers which also transport urban runoff. Backups of raw sewage can occur if excessive stormwater inflow or groundwater infiltration occurs due to leaking joints, defective pipes etc. in aging infrastructure.
Gravelly Hill Interchange, also known as Spaghetti Junction, is a famous junction in the UK. It's junction 6 of the M6 motorway where it meets the A38(M) Aston Expressway in the Gravelly Hill area of Birmingham, England. The interchange was opened on 24 May 1972.
Danebury is an Iron Age hill fort in Hampshire, England, about 19 kilometres (12 mi) north-west of Winchester. The site, covering 5 hectares, was excavated by Barry Cunliffe in the 1970s. Danebury is considered a type-site for hill forts, and was important in developing the understanding of hill forts, as very few others have been so intensively excavated.
The Isles-class trawlers were a class of naval trawler used by the Royal Navy, Royal Canadian Navy and Royal New Zealand Navy during World War II.
The Stone Arch Bridge is a former railroad bridge crossing the Mississippi River at Saint Anthony Falls in downtown Minneapolis, Minnesota. It is the only arched bridge made of stone on the entire Mississippi River. It is the second oldest bridge on the river next to Eads Bridge. The bridge was built to connect the railway system to the new Union Depot, which at that time was planned to be built between Hennepin Avenue and Nicollet Avenue. The bridge was completed in 1883, costing $650,000 at the time. 117 Portland Avenue is the general address of the historic complex.
DNA repair is a collection of processes by which a cell identifies and corrects damage to the DNA molecules that encode its genome. In human cells, both normal metabolic activities and environmental factors such as radiation can cause DNA damage, resulting in tens of thousands of individual molecular lesions per cell per day. Many of these lesions cause structural damage to the DNA molecule and can alter or eliminate the cell's ability to transcribe the gene that the affected DNA encodes. Other lesions induce potentially harmful mutations in the cell's genome, which affect the survival of its daughter cells after it undergoes mitosis. As a consequence, the DNA repair process is constantly active as it responds to damage in the DNA structure. When normal repair processes fail, and when cellular apoptosis does not occur, irreparable DNA damage may occur, including double-strand breaks and DNA crosslinkages. This can eventually lead to malignant tumors, or cancer as per the two hit hypothesis.
A neoplasm is a type of abnormal and excessive growth of tissue. The process that occurs to form or produce a neoplasm is called neoplasia. The growth of a neoplasm is uncoordinated with that of the normal surrounding tissue, and persists in growing abnormally, even if the original trigger is removed. This abnormal growth usually forms a mass, when it may be called a tumor.
A cable layer or cable ship is a deep-sea vessel designed and used to lay underwater cables for telecommunications, electric power transmission, military, or other purposes. Cable ships are distinguished by large cable sheaves for guiding cable over bow or stern or both. Bow sheaves, some very large, were characteristic of all cable ships in the past, but newer ships are tending toward having stern sheaves only, as seen in the photo of CS Cable Innovator at the Port of Astoria on this page. The names of cable ships are often preceded by "C.S." as in CS Long Lines.
HMCS Cape Breton was a Royal Canadian Navy Cape-class maintenance ship. Originally built for the Royal Navy as HMS Flamborough Head in 1944, she was transferred in 1952. Upon her commissioning she was the second ship to bear the name Cape Breton. She served operationally from 1953–1964, when she was laid up. She was used as a floating machine shop until the late-1990s, before being sold for use as an artificial reef off the coast of British Columbia.
Homologous recombination is a type of genetic recombination in which genetic information is exchanged between two similar or identical molecules of double-stranded or single-stranded nucleic acids. It is widely used by cells to accurately repair harmful breaks that occur on both strands of DNA, known as double-strand breaks (DSB), in a process called homologous recombinational repair (HRR). Homologous recombination also produces new combinations of DNA sequences during meiosis, the process by which eukaryotes make gamete cells, like sperm and egg cells in animals. These new combinations of DNA represent genetic variation in offspring, which in turn enables populations to adapt during the course of evolution. Homologous recombination is also used in horizontal gene transfer to exchange genetic material between different strains and species of bacteria and viruses.
Aortic valve repair or aortic valve reconstruction is the reconstruction of both form and function of a dysfunctional aortic valve. Most frequently it is used for the treatment of aortic regurgitation. It can also become necessary for the treatment of aortic aneurysm, less frequently for congenital aortic stenosis.
Christchurch is a village located at the top of Christchurch Hill in the Caerleon ward and community of the city of Newport, South Wales. The top of the hill affords panoramic views both towards the Bristol Channel in the south and through the Vale of Usk and into the Monmouthshire countryside to the north. The road, which runs along the crest of the hill, runs westwards to Newport and eastwards towards Caerleon and Catsash.
Polymer concrete is a type of concrete that uses polymer to replace lime-type cements as a binder. In some cases the polymer is used in addition to portland cement to form Polymer Cement Concrete (PCC) or Polymer Modified Concrete (PMC). Polymers in concrete have been overseen by Committee 548 of the American Concrete Institute since 1971.
Sexual reproduction is a type of reproduction that involves a complex life cycle in which a gamete with a single set of chromosomes (haploid) combines with another to produce a zygote that develops into an organism composed of cells with two sets of chromosomes (diploid). Sexual reproduction is the most common life cycle in multicellular eukaryotes, such as animals, fungi and plants. Sexual reproduction does not occur in prokaryotes, but they have processes with similar effects such as bacterial conjugation, transformation and transduction, which may have been precursors to sexual reproduction in early eukaryotes.
Maiden Castle is an Iron Age hill fort, one of many fortified hill-top settlements constructed across Britain during the Iron Age, but one of only seven in the county of Cheshire in northern England. The hill fort was probably occupied from its construction in 600 BC until the Roman conquest of Britain in the 1st century AD. At this time the Cornovii tribe are recorded to have occupied parts of the surrounding area but, because they left no distinctive pottery or metalworking, their occupation has not been verified. Since then it has been quarried and used for military exercises. It is protected as a Scheduled Ancient Monument, and is owned by the National Trust. The hill fort is open to visitors, but unrestricted access to the site has resulted in it being classified as "at high risk" from erosion.
The origin and function of meiosis are currently not well understood scientifically, and would provide fundamental insight into the evolution of sexual reproduction in eukaryotes. There is no current consensus among biologists on the questions of how sex in eukaryotes arose in evolution, what basic function sexual reproduction serves, and why it is maintained, given the basic two-fold cost of sex. It is clear that it evolved over 1.2 billion years ago, and that almost all species which are descendants of the original sexually reproducing species are still sexual reproducers, including plants, fungi, and animals.
A repair ship is a naval auxiliary ship designed to provide maintenance support to warships. Repair ships provide similar services to destroyer, submarine and seaplane tenders or depot ships, but may offer a broader range of repair capability including equipment and personnel for repair of more significant machinery failures or battle damage.
Inguinal hernia surgery is an operation to repair a weakness in the abdominal wall that abnormally allows abdominal contents to slip into a narrow tube called the inguinal canal in the groin region.
References
- ↑ R. W. Aye; L. D. Hill; S. J. Kraemer; P. Snopkowski P. (May 1994). "Early results with the laparoscopic Hill repair". Am J Surg. 167 (5): 542–546. doi:10.1016/0002-9610(94)90254-2. PMID 8185045.
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