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Flue-gas desulfurization-FGD chemistry-Another important design consideration associated with wet FGD systems is that the flue gas exiting the absorber is saturated with water and still contains some SO2. These gases are highly corrosive to any downstream equipment such as fans, ducts, and stacks. Two methods that may ... | milkshake721/2.1M-wiki-STEM |
Flue-gas desulfurization-FGD chemistry-Scrubbing with an alkali solid or solution SO2 is an acid gas, and, therefore, the typical sorbent slurries or other materials used to remove the SO2 from the flue gases are alkaline. The reaction taking place in wet scrubbing using a CaCO3 (limestone) slurry produces calcium sulf... | milkshake721/2.1M-wiki-STEM |
Flue-gas desulfurization-FGD chemistry-FGD scrubbers produce a scaling wastewater that requires treatment to meet U.S. federal discharge regulations. However, technological advancements in ion-exchange membranes and electrodialysis systems has enabled high-efficiency treatment of FGD wastewater to meet recent EPA disch... | milkshake721/2.1M-wiki-STEM |
Flue-gas desulfurization-FGD chemistry-Venturi-rod scrubbers A venturi scrubber is a converging/diverging section of duct. The converging section accelerates the gas stream to high velocity. When the liquid stream is injected at the throat, which is the point of maximum velocity, the turbulence caused by the high gas v... | milkshake721/2.1M-wiki-STEM |
Flue-gas desulfurization-FGD chemistry-For simultaneous removal of SO2 and fly ash, venturi scrubbers can be used. In fact, many of the industrial sodium-based throwaway systems are venturi scrubbers originally designed to remove particulate matter. These units were slightly modified to inject a sodium-based scrubbing ... | milkshake721/2.1M-wiki-STEM |
Flue-gas desulfurization-FGD chemistry-Packed bed scrubbers A packed scrubber consists of a tower with packing material inside. This packing material can be in the shape of saddles, rings, or some highly specialized shapes designed to maximize the contact area between the dirty gas and liquid. Packed towers typically o... | milkshake721/2.1M-wiki-STEM |
Flue-gas desulfurization-FGD chemistry-Spray towers A spray tower is the simplest type of scrubber. It consists of a tower with spray nozzles, which generate the droplets for surface contact. Spray towers are typically used when circulating a slurry (see below). The high speed of a venturi would cause erosion problems,... | milkshake721/2.1M-wiki-STEM |
Flue-gas desulfurization-FGD chemistry-Counter-current packed towers are infrequently used because they have a tendency to become plugged by collected particles or to scale when lime or limestone scrubbing slurries are used. | milkshake721/2.1M-wiki-STEM |
Flue-gas desulfurization-FGD chemistry-Scrubbing reagent As explained above, alkaline sorbents are used for scrubbing flue gases to remove SO2. Depending on the application, the two most important are lime and sodium hydroxide (also known as caustic soda). Lime is typically used on large coal- or oil-fired boilers as f... | milkshake721/2.1M-wiki-STEM |
Flue-gas desulfurization-FGD chemistry-Caustic soda is limited to smaller combustion units because it is more expensive than lime, but it has the advantage that it forms a solution rather than a slurry. This makes it easier to operate. It produces a "spent caustic" solution of sodium sulfite/bisulfite (depending on the... | milkshake721/2.1M-wiki-STEM |
Flue-gas desulfurization-FGD chemistry-Scrubbing with sodium sulfite solution It is possible to scrub sulfur dioxide by using a cold solution of sodium sulfite; this forms a sodium hydrogen sulfite solution. By heating this solution it is possible to reverse the reaction to form sulfur dioxide and the sodium sulfite so... | milkshake721/2.1M-wiki-STEM |
Flue-gas desulfurization-FGD chemistry-In some ways this can be thought of as being similar to the reversible liquid–liquid extraction of an inert gas such as xenon or radon (or some other solute which does not undergo a chemical change during the extraction) from water to another phase. While a chemical change does oc... | milkshake721/2.1M-wiki-STEM |
Flue-gas desulfurization-FGD chemistry-Gas-phase oxidation followed by reaction with ammonia A new, emerging flue gas desulfurization technology has been described by the IAEA. It is a radiation technology where an intense beam of electrons is fired into the flue gas at the same time as ammonia is added to the gas. The... | milkshake721/2.1M-wiki-STEM |
Flue-gas desulfurization-FGD chemistry-The action of the electron beam is to promote the oxidation of sulfur dioxide to sulfur(VI) compounds. The ammonia reacts with the sulfur compounds thus formed to produce ammonium sulfate, which can be used as a nitrogenous fertilizer. In addition, it can be used to lower the nitr... | milkshake721/2.1M-wiki-STEM |
Flue-gas desulfurization-Facts and statistics-The information in this section was obtained from a US EPA published fact sheet.Flue gas desulfurization scrubbers have been applied to combustion units firing coal and oil that range in size from 5 MW to 1,500 MW. Scottish Power are spending £400 million installing FGD at ... | milkshake721/2.1M-wiki-STEM |
Flue-gas desulfurization-Facts and statistics-FGD has been fitted by RWE npower at Aberthaw Power Station in south Wales using the seawater process and works successfully on the 1,580 MW plant.
Approximately 85% of the flue gas desulfurization units installed in the US are wet scrubbers, 12% are spray dry systems, and ... | milkshake721/2.1M-wiki-STEM |
Flue-gas desulfurization-Facts and statistics-The capital, operating and maintenance costs per short ton of SO2 removed (in 2001 US dollars) are: For wet scrubbers larger than 400 MW, the cost is $200 to $500 per ton For wet scrubbers smaller than 400 MW, the cost is $500 to $5,000 per ton For spray dry scrubbers large... | milkshake721/2.1M-wiki-STEM |
Flue-gas desulfurization-Alternative methods of reducing sulfur dioxide emissions-An alternative to removing sulfur from the flue gases after burning is to remove the sulfur from the fuel before or during combustion. Hydrodesulfurization of fuel has been used for treating fuel oils before use. Fluidized bed combustion ... | milkshake721/2.1M-wiki-STEM |
Flue-gas desulfurization-Alternative methods of reducing sulfur dioxide emissions-This elemental sulfur is then separated and finally recovered at the end of the process for further usage in, for example, agricultural products. Safety is one of the greatest benefits of this method, as the whole process takes place at a... | milkshake721/2.1M-wiki-STEM |
Breast cancer management-Breast cancer management-Breast cancer management takes different approaches depending on physical and biological characteristics of the disease, as well as the age, over-all health and personal preferences of the patient. Treatment types can be classified into local therapy (surgery and radiot... | milkshake721/2.1M-wiki-STEM |
Breast cancer management-Breast cancer management-Historically, breast cancer was treated with radical surgery alone. Advances in the understanding of the natural course of breast cancer as well as the development of systemic therapies allowed for the use of breast-conserving surgeries, however, the nomenclature of vie... | milkshake721/2.1M-wiki-STEM |
Breast cancer management-Breast cancer management-The mainstay of breast cancer management is surgery for the local and regional tumor, followed (or preceded) by a combination of chemotherapy, radiotherapy, endocrine (hormone) therapy, and targeted therapy. Research is ongoing for the use of immunotherapy in breast can... | milkshake721/2.1M-wiki-STEM |
Breast cancer management-Staging-Staging breast cancer is the initial step to help physicians determine the most appropriate course of treatment. As of 2016, guidelines incorporated biologic factors, such as tumor grade, cellular proliferation rate, estrogen and progesterone receptor expression, human epidermal growth ... | milkshake721/2.1M-wiki-STEM |
Breast cancer management-Staging-The TNM staging system of a cancer is a measurement of the physical extent of the tumor and its spread, where: T stands for the main (primary) tumor (range of T0-T4) N stands for spread to nearby lymph nodes (range of N0-N3) M stands for metastasis (spread to distant parts of the body; ... | milkshake721/2.1M-wiki-STEM |
Breast cancer management-Classification-Breast cancer is classified into three major subtypes for the purpose of predicting response to treatment. These are determined by the presence or absence of receptors on the cells of the tumor. The three major subgroups are: Luminal-type, which are tumors positive for hormone re... | milkshake721/2.1M-wiki-STEM |
Breast cancer management-Surgery-Surgery is the primary management for breast cancer. Depending on staging and biologic characteristics of the tumor, surgery can be a lumpectomy (removal of the lump only), a mastectomy, or a modified radical mastectomy. Lymph nodes are often included in the scope of breast tumor remova... | milkshake721/2.1M-wiki-STEM |
Breast cancer management-Surgery-However, mastectomy may be the preferred treatment in certain instances: Two or more tumors exist in different areas of the breast (a "multifocal" cancer) The breast has previously received radiotherapy The tumor is large relative to the size of the breast The patient has had scleroderm... | milkshake721/2.1M-wiki-STEM |
Breast cancer management-Surgery-Standard practice requires the surgeon to establish that the tissue removed in the operation has margins clear of cancer, indicating that the cancer has been completely excised. Additional surgery may be necessary if the removed tissue does not have clear margins, sometimes requiring re... | milkshake721/2.1M-wiki-STEM |
Breast cancer management-Surgery-During the operation, the lymph nodes in the axilla are also considered for removal. In the past, large axillary operations took out 10 to 40 nodes to establish whether cancer had spread. This had the unfortunate side effect of frequently causing lymphedema of the arm on the same side, ... | milkshake721/2.1M-wiki-STEM |
Breast cancer management-Surgery-Ovary removal Prophylactic oophorectomy may be prudent in women who are at a high risk for recurrence or are seeking an alternative to endocrine therapy as it removes the primary source of estrogen production in pre-menopausal women. Women who are carriers of a BRCA mutation have an inc... | milkshake721/2.1M-wiki-STEM |
Breast cancer management-Surgery-Breast reconstruction Breast reconstruction surgery is the rebuilding of the breast after breast cancer surgery, and is included in holistic approaches to cancer management to address identity and emotional aspects of the disease. Reconstruction can take place at the same time as cancer... | milkshake721/2.1M-wiki-STEM |
Breast cancer management-Surgery-Investigational surgical management Cryoablation is an experimental therapy available for women with small or early-stage breast cancer. The treatment freezes, then defrosts tumors using small needles so that only the harmful tissue is damaged and ultimately dies. This technique may pro... | milkshake721/2.1M-wiki-STEM |
Breast cancer management-Radiation therapy-Radiation therapy is an adjuvant treatment for most women who have undergone lumpectomy and for some women who have mastectomy surgery. In these cases the purpose of radiation is to reduce the chance that the cancer will recur locally (within the breast or axilla). Radiation t... | milkshake721/2.1M-wiki-STEM |
Breast cancer management-Radiation therapy-Radiation therapy can be delivered by external beam radiotherapy, brachytherapy (internal radiotherapy), or by intra-operative radiotherapy (IORT). In the case of external beam radiotherapy, X-rays are delivered from outside the body by a machine called a Linear Accelerator or... | milkshake721/2.1M-wiki-STEM |
Breast cancer management-Radiation therapy-Radiation therapy eliminates the microscopic cancer cells that may remain near the area where the tumor was surgically removed. The dose of radiation must be strong enough to ensure the elimination of cancer cells. However, radiation affects normal cells and cancer cells alike... | milkshake721/2.1M-wiki-STEM |
Breast cancer management-Radiation therapy-Indications for radiation Radiation treatment is mainly effective in reducing the risk of local relapse in the affected breast. Therefore, it is recommended in most cases of breast conserving surgeries and less frequently after mastectomy. Indications for radiation treatment a... | milkshake721/2.1M-wiki-STEM |
Breast cancer management-Radiation therapy-In general recommendations would include radiation: As part of breast conserving therapy. | milkshake721/2.1M-wiki-STEM |
Breast cancer management-Radiation therapy-After mastectomy for patients with higher risk of recurrence because of conditions such as a large primary tumor or substantial involvement of the lymph nodes.Other factors which may influence adding adjuvant radiation therapy: Tumor close to or involving the margins on pathol... | milkshake721/2.1M-wiki-STEM |
Breast cancer management-Radiation therapy-This usually involves treating the whole breast in the case of breast lumpectomy or the whole chest wall in the case of mastectomy. Lumpectomy patients with early-stage breast cancer may be eligible for a newer, shorter form of treatment called "breast brachytherapy". This app... | milkshake721/2.1M-wiki-STEM |
Breast cancer management-Radiation therapy-Improvements in computers and treatment delivery technology have led to more complex radiotherapy treatment options. One such new technology is using IMRT (intensity modulated radiation therapy), which can change the shape and intensity of the radiation beam making "beamlets" ... | milkshake721/2.1M-wiki-STEM |
Breast cancer management-Radiation therapy-APBI treatments can be given as brachytherapy or external beam with a linear accelerator. These treatments are usually limited to women with well-defined tumors that have not spread. A meta-analysis of randomised trials of partial breast irradiation (PBI) vs. whole breast irra... | milkshake721/2.1M-wiki-STEM |
Breast cancer management-Radiation therapy-A study is currently underway by the National Surgical Breast and Bowel Project (NSABP) to determine whether limiting radiation therapy to only the tumor site following lumpectomy is as effective as radiating the whole breast.
New technology has also allowed more precise deliv... | milkshake721/2.1M-wiki-STEM |
Breast cancer management-Radiation therapy-The TARGIT-A trial was an international randomised controlled non-inferiority phase III clinical trial led from University College London. 28 centres in 9 countries accrued 2,232 patients to test whether TARGIT can replace the whole course of radiotherapy in selected patients.... | milkshake721/2.1M-wiki-STEM |
Breast cancer management-Systemic therapy-Systemic therapy uses medications to treat cancer cells throughout the body. Any combination of systemic treatments may be used to treat breast cancer. Standard of care systemic treatments include chemotherapy, endocrine therapy and targeted therapy.
Chemotherapy Chemotherapy (... | milkshake721/2.1M-wiki-STEM |
Breast cancer management-Systemic therapy-Hormonal therapy Patients with estrogen receptor-positive tumors are candidates for receiving endocrine therapy to slow the progression of breast tumors or to reduce chance of relapse. Endocrine therapy is usually administered after surgery, chemotherapy, and radiotherapy have ... | milkshake721/2.1M-wiki-STEM |
Breast cancer management-Systemic therapy-Antiestrogen therapy Antiestrogen therapy is used in the treatment of breast cancer in women with estrogen receptor-positive breast tumors. Antiestrogen therapy includes medications like the following: Selective estrogen receptor modulators (SERMs) like tamoxifen and toremifene... | milkshake721/2.1M-wiki-STEM |
Breast cancer management-Systemic therapy-Estrogen therapy Estrogen therapy for treatment of breast cancer was first reported to be effective in the early 1940s and was the first hormonal therapy to be used for breast cancer. Estrogen therapy for breast cancer has been described as paradoxical and has been referred to ... | milkshake721/2.1M-wiki-STEM |
Breast cancer management-Systemic therapy-Androgen therapy Androgens and anabolic steroids such as testosterone, fluoxymesterone, drostanolone propionate, epitiostanol, and mepitiostane have historically been used to treat breast cancer because of their antiestrogenic effects in the breasts. However, they are now rarel... | milkshake721/2.1M-wiki-STEM |
Breast cancer management-Systemic therapy-Targeted therapy In patients whose cancer expresses an over-abundance of the HER2 protein, a monoclonal antibody known as trastuzumab (Herceptin) is used to block the activity of the HER2 protein in breast cancer cells, slowing their growth.
In the advanced cancer setting, tras... | milkshake721/2.1M-wiki-STEM |
Breast cancer management-Managing side effects-Drugs and radiotherapy given for cancer can cause unpleasant side effects such as nausea and vomiting, mouth sores, dermatitis, and menopausal symptoms. Around a third of patients with cancer use complementary therapies, including homeopathic medicines, to try to reduce th... | milkshake721/2.1M-wiki-STEM |
Breast cancer management-Managing side effects-Insomnia It was believed that one would find a bi-directional relationship between insomnia and pain, but instead it was found that trouble sleeping was more likely a cause, rather than a consequence, of pain in patients with cancer. An early intervention to manage sleep w... | milkshake721/2.1M-wiki-STEM |
Breast cancer management-Managing side effects-Hot flushes Lifestyle adjustments are usually suggested first to manage hot flushes (or flashes) due to endocrine therapy. This can include avoiding triggers such as alcohol, caffeine and smoking. If hot flashes continue, and depending on their frequency and severity, seve... | milkshake721/2.1M-wiki-STEM |
Breast cancer management-Managing side effects-Lymphedema Some patients develop lymphedema, as a result of axillary node dissection or of radiation treatment to the lymph nodes. Although traditional recommendations limited exercise, a new study shows that participating in a safe, structured weight-lifting routine can h... | milkshake721/2.1M-wiki-STEM |
Breast cancer management-Managing side effects-Upper-limb dysfunction Upper-limb dysfunction is a common side effect of breast cancer treatment. Shoulder range of motion can be impaired after surgery. Exercise can meaningfully improve should range of motion in women with breast cancer. An exercise programme can be star... | milkshake721/2.1M-wiki-STEM |
Breast cancer management-Managing side effects-Side effects of radiation therapy External beam radiation therapy is a non-invasive treatment with some short term and some longer-term side effects. Patients undergoing some weeks of treatment usually experience fatigue caused by the healthy tissue repairing itself and as... | milkshake721/2.1M-wiki-STEM |
Breast cancer management-Managing side effects-The use of adjuvant radiation has significant potential effects if the patient has to later undergo breast reconstruction surgery. Fibrosis of chest wall skin from radiation negatively affects skin elasticity and makes tissue expansion techniques difficult. Traditionally m... | milkshake721/2.1M-wiki-STEM |
Breast cancer management-Managing side effects-Studies suggest APBI may reduce the side effects associated with radiation therapy, because it treats only the tumor cavity and the surrounding tissue. In particular, a device that uses multiple catheters and allows modulation of the radiation dose delivered by each of the... | milkshake721/2.1M-wiki-STEM |
Adobe PageMaker-Adobe PageMaker-Adobe PageMaker (formerly Aldus PageMaker) is a discontinued desktop publishing computer program introduced in 1985 by the Aldus Corporation on the Apple Macintosh. The combination of the Macintosh's graphical user interface, PageMaker publishing software, and the Apple LaserWriter laser... | milkshake721/2.1M-wiki-STEM |
Adobe PageMaker-Release history-Aldus Pagemaker 1.0 was released in July 1985 for the Macintosh and in December 1986 for the IBM PC. | milkshake721/2.1M-wiki-STEM |
Adobe PageMaker-Release history-Aldus Pagemaker 1.2 for Macintosh was released in 1986 and added support for PostScript fonts built into LaserWriter Plus or downloaded to the memory of other output devices. PageMaker was awarded a Codie award for Best New Use of a Computer in 1986. In October 1986, a version of Pagemak... | milkshake721/2.1M-wiki-STEM |
Adobe PageMaker-Release history-Aldus Pagemaker 2.0 was released in 1987. Until May 1987, the initial Windows release was bundled with a full version of Windows 1.0.3; after that date, a "Windows-runtime" without task-switching capabilities was included. Thus, users who did not have Windows could run the application fr... | milkshake721/2.1M-wiki-STEM |
Adobe PageMaker-Release history-Adobe PageMaker 7.0 was the final version made available. It was released 9 July 2001, though updates have been released for the two supported platforms since. The Macintosh version runs only in Mac OS 9 or earlier; there is no native support for Mac OS X, and it does not run on Intel-ba... | milkshake721/2.1M-wiki-STEM |
Adobe PageMaker-End of development-Development of PageMaker had flagged in the later years at Aldus and, by 1998, PageMaker had lost almost the entire professional market to the comparatively feature-rich QuarkXPress 3.3, released in 1992, and 4.0, released in 1996. Quark stated its intention to buy out Adobe and to di... | milkshake721/2.1M-wiki-STEM |
Adobe PageMaker-Reception-BYTE in 1989 listed PageMaker 3.0 as among the "Distinction" winners of the BYTE Awards, stating that it "is the program that showed many of us how to use the Macintosh to its full potential". | milkshake721/2.1M-wiki-STEM |
Adobe PageMaker-File formats-Adobe PageMaker file formats use various filename extensions, including PMD, PM3, PM4, PM5, PM6 and P65; these should be able to be opened in the applications Collabora Online, LibreOffice or Apache OpenOffice, they can then be saved into the OpenDocument format or other file formats. | milkshake721/2.1M-wiki-STEM |
Farm water-Farm water-Farm water, also known as agricultural water, is water committed for use in the production of food and fibre and collecting for further resources. In the US, some 80% of the fresh water withdrawn from rivers and groundwater is used to produce food and other agricultural products. Farm water may in... | milkshake721/2.1M-wiki-STEM |
Farm water-Farm water-Its study is called agricultural hydrology. | milkshake721/2.1M-wiki-STEM |
Farm water-Farm water-Water is one of the most fundamental parts of the global economy. In areas without healthy water resources or sanitation services, economic growth cannot be sustained. Without access to clean water, nearly every industry would suffer, most notably agriculture. As water scarcity grows as a global c... | milkshake721/2.1M-wiki-STEM |
Farm water-Livestock water use-Livestock and meat production have some of the largest water footprints of the agricultural industry, taking nearly 1,800 gallons of water to produce one pound of beef and 576 gallons for pork. About 108 gallons of water are needed to harvest one pound of corn. Livestock production is als... | milkshake721/2.1M-wiki-STEM |
Farm water-Livestock water use-Cattle The beef and dairy industries are the most lucrative branches of the U.S. agricultural industry, but they are also the most resource intensive. To date, beef is the most popular of the meats; the U.S. alone produced 25.8 billion pounds in 2013. In this same year, 201.2 billion poun... | milkshake721/2.1M-wiki-STEM |
Farm water-Livestock water use-Water scarcity is not necessarily a new issue, however, cattle ranchers in America have been cutting herd sizes since the 1950s in efforts to curb water and manufacturing costs. This shift has led to more efficient feeding and health methods, allowing ranchers to harvest more beef per ani... | milkshake721/2.1M-wiki-STEM |
Farm water-Livestock water use-Poultry and fowl Water is one of the most crucial aspects of poultry raising, as like all animals, they use this to carry food through their system, assist in digestion, and regulate body temperature. Farmers monitor flock water consumption to measure the overall health of their birds. As... | milkshake721/2.1M-wiki-STEM |
Farm water-Horticulture water use-With modern advancements, crops are being cultivated year round in countries all around the world. As water usage becomes a more pervasive global issue, irrigation practices for crops are being refined and becoming more sustainable. While several irrigation systems are used, these may ... | milkshake721/2.1M-wiki-STEM |
Farm water-Scarcity of water in agriculture-About 60 years ago, the common perception was that water was an infinite resource. At that time, fewer than half the current number of people were on the planet. Standard of living was not as high, so individuals consumed fewer calories, and ate less meat, so less water was n... | milkshake721/2.1M-wiki-STEM |
Farm water-Sustainable water use-While water use affects environmental degradation and economic growth, it is also sparking innovation regarding new irrigation methods. In 2006, the USDA predicted that if the agricultural sector improved water efficiency by just 10%, farms could save upwards of $200 million per year. M... | milkshake721/2.1M-wiki-STEM |
Reduced product-Reduced product-In model theory, a branch of mathematical logic, and in algebra, the reduced product is a construction that generalizes both direct product and ultraproduct. | milkshake721/2.1M-wiki-STEM |
Reduced product-Reduced product-Let {Si | i ∈ I} be a family of structures of the same signature σ indexed by a set I, and let U be a filter on I. The domain of the reduced product is the quotient of the Cartesian product ∏i∈ISi by a certain equivalence relation ~: two elements (ai) and (bi) of the Cartesian product ar... | milkshake721/2.1M-wiki-STEM |
Reduced product-Reduced product-Operations from σ are interpreted on the reduced product by applying the operation pointwise. Relations are interpreted by R((ai1)/∼,…,(ain)/∼)⟺{i∈I∣RSi(ai1,…,ain)}∈U.
For example, if each structure is a vector space, then the reduced product is a vector space with addition defined as (a... | milkshake721/2.1M-wiki-STEM |
Journal of General Virology-Journal of General Virology-Journal of General Virology is a not-for-profit peer-reviewed scientific journal published by the Microbiology Society. The journal was established in 1967 and covers research into animal, insect and plants viruses, also fungal viruses, prokaryotic viruses, and TS... | milkshake721/2.1M-wiki-STEM |
Journal of General Virology-Journal-Article types Journal of General Virology publishes primary research articles, Reviews, Short Communications, Personal Views, and Editorials.
Since 2017 the journal has partnered with the International Committee on Taxonomy of Viruses to publish Open Access ICTV Virus Taxonomy Profil... | milkshake721/2.1M-wiki-STEM |
Journal of General Virology-Open access policy-Journal of General Virology is a hybrid title and allows authors to publish subscription articles free-of-charge. Authors can also publish Open Access articles under a Creative Commons Attribution license (CC-BY) by either paying an article processing charge (APC) or fee-f... | milkshake721/2.1M-wiki-STEM |
Geometry E-Geometry E-The Geometry E is a battery-powered subcompact crossover produced by Chinese auto manufacturer Geely under the Geometry brand. | milkshake721/2.1M-wiki-STEM |
Geometry E-Overview-The Geometry E is officially the third brand new model of the Geometry brand, while replacing the short-lived Geometry EX3 sold in 2021 alone. It was developed based on the same platform as the Geely Vision X3 and the Geometry EX3 rebadged variant, and comes in three trims; Cute Tiger, Linglong Tige... | milkshake721/2.1M-wiki-STEM |
Evolution of the eye-Evolution of the eye-Many scientists have found the evolution of the eye attractive to study because the eye distinctively exemplifies an analogous organ found in many animal forms. Simple light detection is found in bacteria, single-celled organisms, plants and animals. Complex, image-forming eyes... | milkshake721/2.1M-wiki-STEM |
Evolution of the eye-Evolution of the eye-Eyes vary in their visual acuity, the range of wavelengths they can detect, their sensitivity in low light, their ability to detect motion or to resolve objects, and whether they can discriminate colours. | milkshake721/2.1M-wiki-STEM |
Evolution of the eye-History of research-In 1802, philosopher William Paley called it a miracle of "design." In 1859, Charles Darwin himself wrote in his Origin of Species, that the evolution of the eye by natural selection seemed at first glance "absurd in the highest possible degree". | milkshake721/2.1M-wiki-STEM |
Evolution of the eye-History of research-However, he went on that despite the difficulty in imagining it, its evolution was perfectly feasible: ... if numerous gradations from a simple and imperfect eye to one complex and perfect can be shown to exist, each grade being useful to its possessor, as is certainly the case;... | milkshake721/2.1M-wiki-STEM |
Evolution of the eye-History of research-He suggested a stepwise evolution from "an optic nerve merely coated with pigment, and without any other mechanism" to "a moderately high stage of perfection", and gave examples of existing intermediate steps. Current research is investigating the genetic mechanisms underlying e... | milkshake721/2.1M-wiki-STEM |
Evolution of the eye-Rate of evolution-The first fossils of eyes found to date are from the Ediacaran period (about 555 million years ago). The lower Cambrian had a burst of apparently rapid evolution, called the "Cambrian explosion". One of the many hypotheses for "causes" of the Cambrian explosion is the "Light Switc... | milkshake721/2.1M-wiki-STEM |
Evolution of the eye-Rate of evolution-The rate of eye evolution is difficult to estimate because the fossil record, particularly of the lower Cambrian, is poor. How fast a circular patch of photoreceptor cells can evolve into a fully functional vertebrate eye has been estimated based on rates of mutation, relative adv... | milkshake721/2.1M-wiki-STEM |
Evolution of the eye-Origins of the eye-Whether the eye evolved once or many times depends on the definition of an eye. All eyed animals share much of the genetic machinery for eye development. This suggests that the ancestor of eyed animals had some form of light-sensitive machinery – even if it was not a dedicated op... | milkshake721/2.1M-wiki-STEM |
Evolution of the eye-Stages of evolution-The earliest predecessors of the eye were photoreceptor proteins that sense light, found even in unicellular organisms, called "eyespots". Eyespots can sense only ambient brightness: they can distinguish light from dark, sufficient for photoperiodism and daily synchronization of... | milkshake721/2.1M-wiki-STEM |
Evolution of the eye-Stages of evolution-Early eyes The basic light-processing unit of eyes is the photoreceptor cell, a specialized cell containing two types of molecules bound to each other and located in a membrane: the opsin, a light-sensitive protein; and a chromophore, the pigment that absorbs light. Groups of su... | milkshake721/2.1M-wiki-STEM |
Evolution of the eye-Stages of evolution-These complex optical systems started out as the multicellular eyepatch gradually depressed into a cup, which first granted the ability to discriminate brightness in directions, then in finer and finer directions as the pit deepened. While flat eyepatches were ineffective at det... | milkshake721/2.1M-wiki-STEM |
Evolution of the eye-Stages of evolution-After the photosensitive cell region invaginated, there came a point when reducing the width of the light opening became more efficient at increasing visual resolution than continued deepening of the cup. By reducing the size of the opening, organisms achieved true imaging, allo... | milkshake721/2.1M-wiki-STEM |
Evolution of the eye-Stages of evolution-Lens formation and diversification In a lensless eye, the light emanating from a distant point hits the back of the eye with about the same size as the eye's aperture. With the addition of a lens this incoming light is concentrated on a smaller surface area, without reducing the... | milkshake721/2.1M-wiki-STEM |
Evolution of the eye-Stages of evolution-Crystallins Vertebrate lenses are composed of adapted epithelial cells which have high concentrations of the protein crystallin. These crystallins belong to two major families, the α-crystallins and the βγ-crystallins. Both categories of proteins were originally used for other f... | milkshake721/2.1M-wiki-STEM |
Evolution of the eye-Stages of evolution-Aqueous humor, iris, and cornea Independently, a transparent layer and a nontransparent layer may split forward from the lens: a separate cornea and iris. (These may happen before or after crystal deposition, or not at all.) Separation of the forward layer again forms a humour, ... | milkshake721/2.1M-wiki-STEM |
Evolution of the eye-Stages of evolution-Polarization vision Polarization is the organization of disordered light into linear arrangements, which occurs when light passes through slit like filters, as well as when passing into a new medium. Sensitivity to polarized light is especially useful for organisms whose habitat... | milkshake721/2.1M-wiki-STEM |
Evolution of the eye-Stages of evolution-Focusing mechanism By utilizing the iris sphincter muscle and the ciliary body, some species move the lens back and forth, some stretch the lens flatter. Another mechanism regulates focusing chemically and independently of these two, by controlling growth of the eye and maintain... | milkshake721/2.1M-wiki-STEM |
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