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Each new blood sugar reading provides the feedback to fine-tune and track the body's insulin requirements. Within this strategy, the key specific factors, which have to be determined experimentally, are the blood sugar correction factor and the carbohydrate ratio. The blood sugar correction factor sets both the "proportional gain" and "integral gain" factors for the four feedback loops. When taken too low, deviations from the target blood sugar level are not corrected for effectively, when taken too high, the blood sugar regulation will become unstable. Since in this approach, the carbohydrate ratio is only used to account for non-standard carbohydrate intakes, it is usually not required to work with meal specific ratios.
Proper modeling of the amount of insulin remaining to act in the person's body is essential in this strategy, for instance to ensure that any adjustment in the amount of basal insulin is accounted for when calculating the bolus amounts needed for the meals. Due to the need to account for each insulin's activity profile, analyze past blood sugar trends, and to factor in non-standard carbohydrate intakes and exercise levels, this strategy requires a dedicated smartphone application to handle all the calculations, and to return meaningful dosing recommendations and expected blood sugar levels. Dose calculation Insulin dosage is given by the formula based on the person's blood glucose and carbohydrate intake and these constants: TR = target rate CF = corrective factor KF = carbohydrate factor Blood glucose and target rate are expressed in mg/dL or mmol/L.
Constants should be set by a physician or clinical pharmacist. Abuse The abuse of exogenous insulin carries with it an attendant risk of hypoglycemic coma and death when the amount used is in excess of that required to handle ingested carbohydrate. Acute risks include brain damage, paralysis, and death. Symptoms may include dizziness, weakness, trembling, palpitations, seizures, confusion, headache, drowsiness, coma, diaphoresis and nausea. All persons suffering from overdoses should be referred for medical assessment and treatment, which may last for hours or days. Data from the US National Poison Data System (2013) indicates that 89.3% of insulin cases reported to poison centers are unintentional, as a result of therapeutic error.
Another 10% of cases are intentional, and may reflect attempted suicide, abuse, criminal intent, secondary gain or other unknown reasons. Hypoglycemia that has been induced by exogenous insulin can be chemically detected by examining the ratio of insulin to C-peptide in peripheral circulation. It has been suggested that this type of approach could be used to detect exogenous insulin abuse by athletes. The possibility of using insulin in an attempt to improve athletic performance was suggested as early as the 1998 Winter Olympics in Nagano, Japan, as reported by Peter Sönksen in the July 2001 issue of Journal of Endocrinology.
The question of whether non-diabetic athletes could legally use insulin was raised by a Russian medical officer. Whether insulin would actually improve athletic performance is unclear, but concerns about its use led the International Olympic Committee to ban use of the hormone by non-diabetic athletes in 1998. The book Game of Shadows (2001), by reporters Mark Fainaru-Wada and Lance Williams, included allegations that baseball player Barry Bonds used insulin (as well as other drugs) in the apparent belief that it would increase the effectiveness of the growth hormone he was alleged to be taking. Bonds eventually testified in front of a federal grand jury as part of a government investigation of BALCO.
Bodybuilders in particular are claimed to be using exogenous insulin and other drugs in the belief that they will increase muscle mass. Bodybuilders have been described as injecting up to 10 IU of regular synthetic insulin before eating sugary meals. A 2008 report suggested that insulin is sometimes used in combination with anabolic steroids and growth hormone (GH), and that "Athletes are exposing themselves to potential harm by self‐administering large doses of GH, IGF‐I and insulin". Insulin abuse has been mentioned as a possible factor in the deaths of bodybuilders Ghent Wakefield and Rich Piana. Insulin, human growth hormone (HGH) and insulin-like growth factor 1 (IGF-1) are self-administered by those looking to increase muscle mass beyond the scope offered by anabolic steroids alone.
Their rationale is that since insulin and HGH act synergistically to promote growth, and since IGF-1 is a primary mediator of musculoskeletal growth, the 'stacking' of insulin, HGH and IGF-1 should offer a synergistic growth effect on skeletal muscle. This theory has been supported in recent years by top-level bodybuilders whose competition weight is in excess of of muscle, larger than that of competitors in the past, and with even lower levels of body fat. Detection in biological fluids Insulin is often measured in serum, plasma or blood in order to monitor therapy in people who are diabetic, confirm a diagnosis of poisoning in hospitalized persons or assist in a medicolegal investigation of suspicious death.
Interpretation of the resulting insulin concentrations is complex, given the numerous types of insulin available, various routes of administration, the presence of anti-insulin antibodies in insulin-dependent diabetics and the ex vivo instability of the drug. Other potential confounding factors include the wide-ranging cross-reactivity of commercial insulin immunoassays for the biosynthetic insulin analogs, the use of high-dose intravenous insulin as an antidote to antihypertensive drug overdosage and postmortem redistribution of insulin within the body. The use of a chromatographic technique for insulin assay may be preferable to immunoassay in some circumstances, to avoid the issue of cross-reactivity affecting the quantitative result and also to assist identifying the specific type of insulin in the specimen.
Combination with other antidiabetic drugs A combination therapy of insulin and other antidiabetic drugs appears to be most beneficial in people who are diabetic, who still have residual insulin secretory capacity. A combination of insulin therapy and sulfonylurea is more effective than insulin alone in treating people with type 2 diabetes after secondary failure to oral drugs, leading to better glucose profiles and/or decreased insulin needs. History 1921 Research on the role of pancreas in the nutritive assimilation 1922 Frederick Banting, Charles Best and James Collip use bovine insulin extract in humans in Toronto, Canada. 1922 Leonard Thompson becomes the first human to be treated with insulin.
1922 James D. Havens, son of former congressman James S. Havens, becomes the first American to be treated with insulin. 1922 Elizabeth Hughes Gossett, daughter of the U.S. Secretary of State, becomes the first American to be (officially) treated in Toronto. 1923 Eli Lilly produces commercial quantities of much purer bovine insulin than Banting et al. had used 1923 Farbwerke Hoechst, one of the forerunners of today's Sanofi Aventis, produces commercial quantities of bovine insulin in Germany 1923 Hagedorn founds the Nordisk Insulinlaboratorium in Denmark – forerunner of today's Novo Nordisk 1923 Constance Collier returns to health after being successfully treated with insulin in Strasbourg 1926 Nordisk receives a Danish charter to produce insulin as a non-profit 1936 Canadians D.M.
Scott, A.M. Fisher formulate a zinc insulin mixture and license it to Novo 1936 Hagedorn discovers that adding protamine to insulin prolongs the duration of action of insulin 1946 Nordisk formulates Isophane porcine insulin aka Neutral Protamine Hagedorn or NPH insulin 1946 Nordisk crystallizes a protamine and insulin mixture 1950 Nordisk markets NPH insulin 1953 Novo formulates Lente porcine and bovine insulins by adding zinc for longer lasting insulin 1955 Frederick Sanger determines the amino acid sequence of insulin 1965 Synthesized by total synthesis by Wang Yinglai, Chen-Lu Tsou, et al 1969 Dorothy Crowfoot Hodgkin solves the crystal structure of insulin by X-ray crystallography 1973 Purified monocomponent (MC) insulin is introduced 1973 The U.S. officially "standardized" insulin sold for human use in the U.S. to U-100 (100 units per milliliter).
Prior to that, insulin was sold in different strengths, including U-80 (80 units per milliliter) and U-40 formulations (40 units per milliliter), so the effort to "standardize" the potency aimed to reduce dosage errors and ease doctors' job of prescribing insulin for people. Other countries also followed suit. 1978 Genentech produces biosynthetic human insulin in Escherichia coli bacteria using recombinant DNA techniques, licenses to Eli Lilly 1981 Novo Nordisk chemically and enzymatically converts porcine to human insulin 1982 Genentech synthetic human insulin (above) approved 1983 Eli Lilly and Company produces biosynthetic human insulin with recombinant DNA technology, Humulin 1985 Axel Ullrich sequences a human cell membrane insulin receptor.
1988 Novo Nordisk produces recombinant biosynthetic human insulin 1996 Lilly Humalog "lispro" insulin analogue approved. 2000 Sanofi Aventis Lantus insulin "glargine" analogue approved for clinical use in the US and Europe. 2004 Sanofi Aventis Apidra insulin "glulisine" insulin analogue approved for clinical use in the US. 2006 Novo Nordisk Levemir "detemir" insulin analogue approved for clinical use in the US. Economics The wholesale cost in the developing world is about US$2.39 to $10.61 per 1,000 iu of regular insulin and $2.23 to $10.35 per 1,000 iu of NPH insulin. In the United Kingdom 1,000 iu of regular or NPH insulin costs the NHS £7.48, while this amount of insulin glargine costs £30.68.
In the United States the unit price of insulin has increased steadily from 1991 to 2019. It rose threefold from 2002 to 2013. Costs can be as high as US$900 per month. Concerns were raised in 2016 of pharmaceutical companies working together to increase prices. In January 2019, lawmakers from the United States House of Representatives sent letters to insulin manufacturers Eli Lilly and Co., Sanofi and Novo Nordisk asking for explanations for their rapidly raising insulin prices. The annual cost of insulin for people with type 1 diabetes in the U.S. almost doubled from $2,900 to $5,700 over the period from 2012 to 2016.
Research Inhalation In 2006 the U.S. Food and Drug Administration approved the use of Exubera, the first inhalable insulin. It was withdrawn from the market by its maker as of third quarter 2007, due to lack of acceptance. Inhaled insulin claimed to have similar efficacy to injected insulin, both in terms of controlling glucose levels and blood half-life. Currently, inhaled insulin is short acting and is typically taken before meals; an injection of long-acting insulin at night is often still required. When people were switched from injected to inhaled insulin, no significant difference was observed in HbA1c levels over three months.
Accurate dosing was a particular problem, although people showed no significant weight gain or pulmonary function decline over the length of the trial, when compared to the baseline. Following its commercial launch in 2005 in the United Kingdom, it was not (as of July 2006) recommended by National Institute for Health and Clinical Excellence for routine use, except in cases where there is "proven injection phobia diagnosed by a psychiatrist or psychologist". In January 2008, the world's largest insulin manufacturer, Novo Nordisk, also announced that the company was discontinuing all further development of the company's own version of inhalable insulin, known as the AERx iDMS inhaled insulin system.
Similarly, Eli Lilly and Company ended its efforts to develop its inhaled Air Insulin in March 2008. However, MannKind Corp. (majority owner, Alfred E. Mann) remains optimistic about the concept. Transdermal There are several methods for transdermal delivery of insulin. Pulsatile insulin uses microjets to pulse insulin into the person, mimicking the physiological secretions of insulin by the pancreas. Jet injection had different insulin delivery peaks and durations as compared to needle injection. Some diabetics may prefer jet injectors to hypodermic injection. Both electricity using iontophoresis and ultrasound have been found to make the skin temporarily porous. The insulin administration aspect remains experimental, but the blood glucose test aspect of "wrist appliances" is commercially available.
Researchers have produced a watch-like device that tests for blood glucose levels through the skin and administers corrective doses of insulin through pores in the skin. A similar device, but relying on skin-penetrating "microneedles", was in the animal testing stage in 2015. Intranasal Intranasal insulin is being investigated. A randomized controlled trial that will determine whether intranasal insulin can delay or prevent the onset of type 1 diabetes in at-risk children and young adults is expected to yield results in 2016. By mouth The basic appeal of hypoglycemic agents by mouth is that most people would prefer a pill or an oral liquid to an injection.
However, insulin is a peptide hormone, which is digested in the stomach and gut and in order to be effective at controlling blood sugar, cannot be taken orally in its current form. The potential market for an oral form of insulin is assumed to be enormous, thus many laboratories have attempted to devise ways of moving enough intact insulin from the gut to the portal vein to have a measurable effect on blood sugar. A number of derivatization and formulation strategies are currently being pursued to in an attempt to develop an orally available insulin. Many of these approaches employ nanoparticle delivery systems and several are being tested in clinical trials.
Pancreatic transplantation Another improvement would be a transplantation of the pancreas or beta cell to avoid periodic insulin administration. This would result in a self-regulating insulin source. Transplantation of an entire pancreas (as an individual organ) is difficult and relatively uncommon. It is often performed in conjunction with liver or kidney transplant, although it can be done by itself. It is also possible to do a transplantation of only the pancreatic beta cells. However, islet transplants had been highly experimental for many years, but some researchers in Alberta, Canada, have developed techniques with a high initial success rate (about 90% in one group).
Nearly half of those who got an islet cell transplant were insulin-free one year after the operation; by the end of the second year that number drops to about one in seven. However, researchers at the University of Illinois at Chicago (UIC) have slightly modified the Edmonton Protocol procedure for islet cell transplantation and achieved insulin independence in diabetic people, with fewer but better-functioning pancreatic islet cells. Longer-term studies are needed to validate whether it improves the rate of insulin-independence. Beta cell transplant may become practical in the near future. Additionally, some researchers have explored the possibility of transplanting genetically engineered non-beta cells to secrete insulin.
Clinically testable results are far from realization at this time. Several other non-transplant methods of automatic insulin delivery are being developed in research labs, but none is close to clinical approval. References External links Category:Insulin therapies Category:Eli Lilly and Company brands Category:RTT Category:World Health Organization essential medicines
The fourth season of Superstore, the U.S. television series, was ordered on February 21, 2018. The season premiered on October 4, 2018 and contained 22 episodes. The series continues to air in the same timeslot Thursday at 8:00 PM. The season concluded on May 16, 2019. Superstore follows a group of employees working at Cloud 9, a fictional big-box store in St. Louis, Missouri. The ensemble and supporting cast features America Ferrera, Ben Feldman, Lauren Ash, Colton Dunn, Nico Santos, Nichole Bloom, and Mark McKinney.
Cast Main America Ferrera as Amy Sosa Ben Feldman as Jonah Simms Lauren Ash as Dina Fox Colton Dunn as Garrett McNeil Nico Santos as Mateo Fernando Aquino Liwanag Nichole Bloom as Cheyenne Thompson Mark McKinney as Glenn Sturgis Recurring Michael Bunin as Jeff Sutton Kaliko Kauahi as Sandra Kaluiokalani Johnny Pemberton as Bo Derek Thompson Jon Barinholtz as Marcus White Linda Porter as Myrtle Vartanian Josh Lawson as Tate Staskiewicz Kelly Stables as Kelly Watson Kelly Schumann as Justine Sikowitz Kerri Kenney-Silver as Jerusha Sturgis Irene White as Carol Amir M. Korangy as Sayid Jennifer Irwin as Laurie Neustadt Episodes Production Casting It was announced on September 10, 2018 that former The Middle star Eden Sher had been cast in a guest role as a potential new Cloud 9 employee named Penny, whom Ben Feldman's character Jonah and Colton Dunn’s character Garrett hire during the seasonal months.
Reception The fourth season received critical acclaim with critics saying “Superstore remains a furtively fearless riot in its comedic approach to heavy and issues of the time” with a score of 100% on Rotten Tomatoes. Ratings References External links Category:Superstore Category:2018 American television seasons Category:2019 American television seasons
Meitnerium is a synthetic chemical element with the symbol Mt and atomic number 109. It is an extremely radioactive synthetic element (an element not found in nature, but can be created in a laboratory). The most stable known isotope, meitnerium-278, has a half-life of 4.5 seconds, although the unconfirmed meitnerium-282 may have a longer half-life of 67 seconds. The GSI Helmholtz Centre for Heavy Ion Research near Darmstadt, Germany, first created this element in 1982. It is named after Lise Meitner. In the periodic table, meitnerium is a d-block transactinide element. It is a member of the 7th period and is placed in the group 9 elements, although no chemical experiments have yet been carried out to confirm that it behaves as the heavier homologue to iridium in group 9 as the seventh member of the 6d series of transition metals.
Meitnerium is calculated to have similar properties to its lighter homologues, cobalt, rhodium, and iridium. Introduction History Discovery Meitnerium was first synthesized on August 29, 1982 by a German research team led by Peter Armbruster and Gottfried Münzenberg at the Institute for Heavy Ion Research (Gesellschaft für Schwerionenforschung) in Darmstadt. The team bombarded a target of bismuth-209 with accelerated nuclei of iron-58 and detected a single atom of the isotope meitnerium-266: + → + This work was confirmed three years later at the Joint Institute for Nuclear Research at Dubna (then in the Soviet Union). Naming Using Mendeleev's nomenclature for unnamed and undiscovered elements, meitnerium should be known as eka-iridium.
In 1979, during the Transfermium Wars (but before the synthesis of meitnerium), IUPAC published recommendations according to which the element was to be called unnilennium (with the corresponding symbol of Une), a systematic element name as a placeholder, until the element was discovered (and the discovery then confirmed) and a permanent name was decided on. Although widely used in the chemical community on all levels, from chemistry classrooms to advanced textbooks, the recommendations were mostly ignored among scientists in the field, who either called it "element 109", with the symbol of E109, (109) or even simply 109, or used the proposed name "meitnerium".
The naming of meitnerium was discussed in the element naming controversy regarding the names of elements 104 to 109, but meitnerium was the only proposal and thus was never disputed. The name meitnerium (Mt) was suggested by the GSI team in September 1992 in honor of the Austrian physicist Lise Meitner, a co-discoverer of protactinium (with Otto Hahn), and one of the discoverers of nuclear fission. In 1994 the name was recommended by IUPAC, and was officially adopted in 1997. It is thus the only element named specifically after a non-mythological woman (curium being named for both Pierre and Marie Curie).
Isotopes Meitnerium has no stable or naturally occurring isotopes. Several radioactive isotopes have been synthesized in the laboratory, either by fusing two atoms or by observing the decay of heavier elements. Eight different isotopes of meitnerium have been reported with atomic masses 266, 268, 270, and 274–278, two of which, meitnerium-268 and meitnerium-270, have known but unconfirmed metastable states. A ninth isotope with atomic mass 282 is unconfirmed. Most of these decay predominantly through alpha decay, although some undergo spontaneous fission. Stability and half-lives All meitnerium isotopes are extremely unstable and radioactive; in general, heavier isotopes are more stable than the lighter.
The most stable known meitnerium isotope, 278Mt, is also the heaviest known; it has a half-life of 4.5 seconds. The unconfirmed 282Mt is even heavier and appears to have a longer half-life of 67 seconds. The isotopes 276Mt and 274Mt have half-lives of 0.45 and 0.44 seconds respectively. The remaining five isotopes have half-lives between 1 and 20 milliseconds. The isotope 277Mt, created as the final decay product of 293Ts for the first time in 2012, was observed to undergo spontaneous fission with a half-life of 5 milliseconds. Preliminary data analysis considered the possibility of this fission event instead originating from 277Hs, for it also has a half-life of a few milliseconds, and could be populated following undetected electron capture somewhere along the decay chain.
This possibility was later deemed very unlikely based on observed decay energies of 281Ds and 281Rg and the short half-life of 277Mt, although there is still some uncertainty of the assignment. Regardless, the rapid fission of 277Mt and 277Hs is strongly suggestive of a region of instability for superheavy nuclei with N = 168–170. The existence of this region, characterized by a decrease in fission barrier height between the deformed shell closure at N = 162 and spherical shell closure at N = 184, is consistent with theoretical models. Predicted properties No properties of meitnerium or its compounds have been measured; this is due to its extremely limited and expensive production and the fact that meitnerium and its parents decay very quickly.
Properties of meitnerium metal remain unknown and only predictions are available. Chemical Meitnerium is the seventh member of the 6d series of transition metals. Since element 112 (copernicium) has been shown to be a group 12 metal, it is expected that all the elements from 104 to 111 would continue a fourth transition metal series, with meitnerium as part of the platinum group metals. Calculations on its ionization potentials and atomic and ionic radii are similar to that of its lighter homologue iridium, thus implying that meitnerium's basic properties will resemble those of the other group 9 elements, cobalt, rhodium, and iridium.
Prediction of the probable chemical properties of meitnerium has not received much attention recently. Meitnerium is expected to be a noble metal, and about as noble as silver (the standard electrode potential for the Mt3+/Mt couple is expected to be 0.8 V, close to the +0.7993 V value known for the Ag+/Ag couple). Based on the most stable oxidation states of the lighter group 9 elements, the most stable oxidation states of meitnerium are predicted to be the +6, +3, and +1 states, with the +3 state being the most stable in aqueous solutions. In comparison, rhodium and iridium show a maximum oxidation state of +6, while the most stable states are +4 and +3 for iridium and +3 for rhodium.
The oxidation state +9, represented only by iridium in [IrO4]+, might be possible for its congener meitnerium in the nonafluoride (MtF9) and the [MtO4]+ cation, although [IrO4]+ is expected to be more stable than these meitnerium compounds. The tetrahalides of meitnerium have also been predicted to have similar stabilities to those of iridium, thus also allowing a stable +4 state. It is further expected that the maximum oxidation states of elements from bohrium (element 107) to darmstadtium (element 110) may be stable in the gas phase but not in aqueous solution. Physical and atomic Meitnerium is expected to be a solid under normal conditions and assume a face-centered cubic crystal structure, similarly to its lighter congener iridium.
It should be a very heavy metal with a density of around 37.4 g/cm3, which would be the second-highest of any of the 118 known elements, second only to that predicted for its neighbor hassium (41 g/cm3). In comparison, the densest known element that has had its density measured, osmium, has a density of only 22.61 g/cm3. This results from meitnerium's high atomic weight, the lanthanide and actinide contractions, and relativistic effects, although production of enough meitnerium to measure this quantity would be impractical, and the sample would quickly decay. Meitnerium is also predicted to be paramagnetic. Theoreticians have predicted the covalent radius of meitnerium to be 6 to 10 pm larger than that of iridium.
The atomic radius of meitnerium is expected to be around 128 pm. Experimental chemistry Meitnerium is the first element on the periodic table whose chemistry has not yet been investigated. Unambiguous determination of the chemical characteristics of meitnerium has yet to have been established due to the short half-lives of meitnerium isotopes and a limited number of likely volatile compounds that could be studied on a very small scale. One of the few meitnerium compounds that are likely to be sufficiently volatile is meitnerium hexafluoride (), as its lighter homologue iridium hexafluoride () is volatile above 60 °C and therefore the analogous compound of meitnerium might also be sufficiently volatile; a volatile octafluoride () might also be possible.
For chemical studies to be carried out on a transactinide, at least four atoms must be produced, the half-life of the isotope used must be at least 1 second, and the rate of production must be at least one atom per week. Even though the half-life of 278Mt, the most stable confirmed meitnerium isotope, is 4.5 seconds, long enough to perform chemical studies, another obstacle is the need to increase the rate of production of meitnerium isotopes and allow experiments to carry on for weeks or months so that statistically significant results can be obtained.
Separation and detection must be carried out continuously to separate out the meitnerium isotopes and have automated systems experiment on the gas-phase and solution chemistry of meitnerium, as the yields for heavier elements are predicted to be smaller than those for lighter elements; some of the separation techniques used for bohrium and hassium could be reused. However, the experimental chemistry of meitnerium has not received as much attention as that of the heavier elements from copernicium to livermorium. The Lawrence Berkeley National Laboratory attempted to synthesize the isotope 271Mt in 2002–2003 for a possible chemical investigation of meitnerium because it was expected that it might be more stable than the isotopes around it as it has 162 neutrons, a magic number for deformed nuclei; its half-life was predicted to be a few seconds, long enough for a chemical investigation.
However, no atoms of 271Mt were detected, and this isotope of meitnerium is currently unknown. An experiment determining the chemical properties of a transactinide would need to compare a compound of that transactinide with analogous compounds of some of its lighter homologues: for example, in the chemical characterization of hassium, hassium tetroxide (HsO4) was compared with the analogous osmium compound, osmium tetroxide (OsO4). In a preliminary step towards determining the chemical properties of meitnerium, the GSI attempted sublimation of the rhodium compounds rhodium(III) oxide (Rh2O3) and rhodium(III) chloride (RhCl3).
However, macroscopic amounts of the oxide would not sublimate until 1000 °C and the chloride would not until 780 °C, and then only in the presence of carbon aerosol particles: these temperatures are far too high for such procedures to be used on meitnerium, as most of the current methods used for the investigation of the chemistry of superheavy elements do not work above 500 °C. Following the 2014 successful synthesis of seaborgium hexacarbonyl, Sg(CO)6, studies were conducted with the stable transition metals of groups 7 through 9, suggesting that carbonyl formation could be extended to further probe the chemistries of the early 6d transition metals from rutherfordium to meitnerium inclusive.
Nevertheless, the challenges of low half-lives and difficult production reactions make meitnerium difficult to access for radiochemists, though the isotopes 278Mt and 276Mt are long-lived enough for chemical research and may be produced in the decay chains of 294Ts and 288Mc respectively. 276Mt is likely more suitable, since producing tennessine requires a rare and rather short-lived berkelium target. The isotope 270Mt, observed in the decay chain of 278Nh with a half-life of 0.69 seconds, may also be sufficiently long-lived for chemical investigations, though a direct synthesis route leading to this isotope and more precise measurements of its decay properties would be required.
Notes References Bibliography External links Meitnerium at The Periodic Table of Videos (University of Nottingham) Category:Chemical elements Category:Transition metals Category:Synthetic elements
Pitch correction is an electronic effects unit or audio software that changes the intonation (highness or lowness in pitch) of an audio signal so that all pitches will be notes from the equally tempered system (i.e., like the pitches on a piano). Pitch correction devices do this without affecting other aspects of its sound. Pitch correction first detects the pitch of an audio signal (using a live pitch detection algorithm), then calculates the desired change and modifies the audio signal accordingly. The widest use of pitch corrector devices is in Western popular music on vocal lines. History Prior to the invention of pitch correction, errors in vocal intonation in recordings could only be corrected by re-recording the entire song (in the early era of recording) or, after the development of multitrack recording, by overdubbing the incorrect vocal pitches by re-recording those specific notes or sections.
By the late 70s, engineers were fixing parts using the Eventide Harmonizer H49. Prior to the development of electronic pitch correction devices, there was no way to make "real time" corrections to a live vocal performance in a concert (although lip-syncing was used in some cases where a performer was not able to sing adequately in live performances). Pitch correction was relatively uncommon before 1997, when Antares Audio Technology's Auto-Tune Pitch Correcting Plug-In was introduced. This replaced slow studio techniques with a real-time process that could also be used in live performance. Auto-Tune is still widely used, as are other pitch-correction algorithms including Celemony's Direct Note Access which allows adjustment of individual notes in a polyphonic audio signal, and Celemony's Melodyne.
Pitch correction is now a common feature in digital audio editing software, having first appeared as a Pro Tools plugin and now being found in products such as Apple GarageBand, Apple Logic Pro, Adobe Audition, FL Studio, Digital Performer, and Steinberg Cubase. MorphTune also provides this functionality. It is also available in the form of rackmount hardware, such as the TC-Helicon VoiceOne. There is also a large stompbox pedal that provides pitch correction in a small device that could be used at a show by plugging the vocal microphone into the pedal and then sending the signal to the PA system.
A free VST plugin known as GSnap can also be used to get the same effect. In the Linux FOSS community, Autotalent and Zita-AT1 offer this functionality. Uses Pitch correction The most common use of pitch correctors is to fix wrong intonation (tuning) of notes sung by vocalists in popular music sound recordings. The use of pitch correction speeds up the recording process, because singers do not need to keep singing a song or vocal line and re-recording it until the pitches are correct. The pitch correction software can correct any pitch errors in the singing without the need for overdubbing or re-recording.
While pitch correction is most associated with fixing vocal intonation errors, it can also be used to fix intonation in recorded instrumental parts such as violin, cello or trumpet. Vocal harmony and vibrato Pitch correctors are commonly used in music studios to add the sound of vocal harmony to certain sung words or phrases without re-recording those lines again at the necessary pitches or using backup singers. Depending on the model used, various vocal effects can be added and the better quality devices can be adjusted to allow expression to remain in the music. Some pitch correctors can add vibrato.
Extreme effects While pitch correction devices were initially designed to produce natural-sounding effects, producers discovered that by setting extreme parameter values, unusual effects could be obtained. Pitch correction devices became popular in the late 1990s as a distinctively electronic, vocoder-like voice effect. A notable example of Auto-Tune-based pitch correction is the Cher effect, so named because producer Mark Taylor originated the effect in her 1998 hit song "Believe". The effect has been used by composer John Boswell for his Symphony of Science and Symphony of Bang Goes The Theory (a BBC science show) mash-ups. American Rapper T-Pain is known for his skillful use of this effect.
Criticism One criticism of pitch correction is that it allows recording engineers to create a perfectly in-tune performance from a vocalist who is otherwise not skilled enough to give one, adding a degree of dishonesty to music. This concept was featured in a 2001 episode of The Simpsons, entitled "New Kids on the Blecch". In the episode, a cartoon representation of a pitch corrector (labeled "Studio Magic") was used to make up for the total lack of singing talent in a manufactured boy band, of which Bart Simpson was a member. In 2003, Allison Moorer began attaching stickers to her 2002 album Miss Fortune reading "Absolutely no vocal tuning or pitch-correction was used in the making of this record."
A Chicago Tribune report from 2003 stated that "many successful mainstream artists in most genres of music—perhaps a majority of artists—are using pitch correction". Timothy Powell, a producer/engineer, stated in 2003 that he is "even starting to see vocal tuning devices show up in concert settings"; he states that "That's more of an ethical dilemma—people pay a premium dollar to see artists and artists want people to see them at their best." In 2010, producer Teddy Riley claimed that the processing of Michael Jackson's voice with Melodyne caused fans to question the authenticity of the voice on the posthumous album Michael.
Riley claimed that because he did not have a "final vocal" from Jackson, Melodyne had to be used "to make his voice work with the actual music," "to get him in key" and this resulted in the vibrato sounding "a little off" or "over-processed." See also Audio time stretching and pitch scaling Puberphonia Pitch shift Phase vocoder Lip syncing in music References Vocal Pitch Correction Pedal/Processor Review 2017 - SustainPunch Category:Audio engineering Category:Digital signal processing
Gretchen Mol (born November 8, 1972) is an American actress and former model. She is known for her role as Gillian Darmody in the HBO series Boardwalk Empire (2010–2014). She also appeared in the films Rounders (1998), Celebrity (1998), The Thirteenth Floor (1999), The Notorious Bettie Page (2005), in which she played the title character, 3:10 to Yuma (2007), and Manchester by the Sea (2016). Early life Mol was born in Deep River, Connecticut, where her mother, Janet (née Morgan), is an artist and teacher, and her father is a teacher at RHAM High School. She went to high school with Broadway actor Peter Lockyer, with whom she performed in school musicals and plays.
Her brother, Jim Mol, is a director and editor in the film industry. Mol attended The American Musical and Dramatic Academy and graduated from the William Esper Studio. After summer stock in Vermont, she took a job for a while as an usher at Angelika Film Center. She was living in a Hell's Kitchen walk-up when she was noticed by a talent agent who spotted her working as a hat-check girl at Michael's Restaurant in New York. Stage Mol's acting career began in summer stock theatre in Vermont where she played a variety of roles, including Godspell and 110 in the Shade.
She played Jenny in Neil LaBute's The Shape of Things on stage in both London and New York in 2001, in a role she reprised in the film version, released in 2003. The New York Times critic Ben Brantley, in his review of the play (which he disliked), wrote, "[Mol] gives by far the most persuasive performance as the unworldly Jenny, and you wind up feeling for her disproportionately, only because she seems to be entirely there, in the present tense". In 2004, Mol spent a year singing and dancing as Roxie Hart in the Broadway production of Chicago. In 2014–2015, Mol played the role of Emily in the Broadway debut of Ayad Akhtar's Pulitzer-Prize-winning play Disgraced.
Film In 1994, Mol was spotted by photographer David William Powell. He photographed her in New York's Central Park and replaced her unrepresentative portfolio with professional-looking black-and-white images which landed her on the cover of W within weeks, and foreshadowed her "It Girl" and "Bettie Page" looks. Shortly afterwards, she ended her brief modeling career and entered acting full-time. While major roles have been sporadic, Mol has been in more than 30 feature films. She made her film debut in Spike Lee's 1996 film, Girl 6. She said, "I was auditioning for Guiding Light and I was happy I got a Spike-Lee movie, which was a tiny part, but all of a sudden I had Spike Lee on my resume.
I didn't audition for day player anymore". After Girl 6, New York filmmaker Abel Ferrara took notice and cast her in two movies, The Funeral (1996) and New Rose Hotel (1998). She had a small role in Donnie Brasco (1997), but by now, she was being typecast as "the girlfriend", which she attempted to change by taking a role opposite Jude Law in Music from Another Room (1998), a romantic comedy. The film went virtually unnoticed by critics and audiences. In 1998, she appeared in several notable films, including Rounders, starring Matt Damon and Woody Allen's Celebrity opposite Leonardo DiCaprio.
In 1998, she also came to prominence when she was featured on the cover of Vanity Fair, dubbed the "It Girl of the Nineties" by the magazine. For her second film with Woody Allen, 1999's Sweet and Lowdown, she played a minor role which the Greenwich Village Gazette called "notable". She played the female lead role in the 1999 film The Thirteenth Floor. She played the victim of a con artist in the 2003 film Heavy Put-Away, based on the Terry Southern story. In 2006, she shared the lead in a romantic comedy, Puccini for Beginners, in which her character has a lesbian affair.
Mol worked with Mary Harron for two years as the director struggled to finance The Notorious Bettie Page: "I kind of felt like I lived with it for a while; certainly not as long as Mary Harron did but I got a good chance to really feel like I knew something about Bettie so by the time the role was mine and I was on set, I was pretty confident. I felt like I really worked for it." The next year, 2007, was one of her busiest, with four films in production or in release, including a remake of 3:10 to Yuma starring Russell Crowe, and An American Affair, in which her character, Catherine Caswell, has an affair with John F. Kennedy.
When released in February 2009, the film was harshly criticized by New York Times critic Stephen Holden, though he said that Mol's part was "quite well acted". In April 2008, she began filming Tenure in Philadelphia, working opposite Luke Wilson and Andrew Daly. Though it had received some good reviews after being screened at several film festivals, it was released direct-to-video in February 2010. Television Mol's first television work was in a Coca-Cola commercial. Mol had a small role of Maggie Tilton in the 1996 miniseries Dead Man's Walk, based on the Larry McMurtry novel. She also was in a few episodes of Spin City.
She was the star of the short-lived David E. Kelley series Girls Club (2002), a drama about three women lawyers. The series was not well received and it was cancelled after two episodes. She appeared in two TV remakes of classic films: Picnic (2000), in the role of Madge Owens, and The Magnificent Ambersons as Lucy Morgan (2002). She made a Hallmark Hall of Fame television movie in January 2007, starring in The Valley of Light, a story set in post-World War II based on a novel by Terry Kay. It was her second Hallmark production. She had a minor role in Calm at Sunset in 1996.
She played Norah in The Memory Keeper's Daughter which aired on The Lifetime Channel in the U.S. in April 2008. She played Annie in the ABC series Life on Mars, the U.S. remake of the British show of the same name. It started airing in the U.S. on October 9, 2008 and ran 17 episodes, concluding on April 1, 2009. She had a recurring role on HBO's Boardwalk Empire as Gillian Darmody, a showgirl at the Beaux Arts and mother and incestuous lover to gangster Jimmy Darmody (played by Michael Pitt). In February 2018, she played attorney Sam Henessy in the Netflix series Seven Seconds.
On April 18, 2018, Netflix confirmed the show would not have a second season, deeming it a limited series. Personal life Interviewed by the Associated Press in Baltimore in December 2006, Mol commented about how she maintained her confidence as an actress: "It is an ongoing struggle. Confidence is something that sometimes you have and sometimes you don't. And the older you get, hopefully, the more you have some tools to at least fake it". She married film director Kip Williams on June 1, 2004. Their first child, a son, was born in September 2007. In February 2011, Mol gave birth to their second child, a daughter.
Since becoming a mother, Mol has only taken jobs close to her home in New York City. "I told my agent I didn't want to work in L.A., even if it was the greatest job in the world. I didn't want to compromise." Mol serves as the national spokesperson in the United States for the PMD Foundation, which funds research and awareness of Pelizaeus–Merzbacher disease, a neurological disorder which affects children worldwide. Mol became involved with PMD after one of her cousins died from amyotrophic lateral sclerosis (familiarly known as "Lou Gehrig's Disease"). Filmography Film Television References External links Gretchen Mol shares her favorite NY places at ontheinside.info Gretchen Mol gets notorious as pinup legend Bettie Page at Popentertainment.com, April 17, 2006.
(accessed May 31, 2010) interview at SuicideGirls.com Category:1972 births Category:20th-century American actresses Category:21st-century American actresses Category:Actresses from Connecticut Category:American film actresses Category:American television actresses Category:Living people Category:People from Deep River, Connecticut Category:Theatre World Award winners
Object-oriented design is the process of planning a system of interacting objects for the purpose of solving a software problem. It is one approach to software design. Overview An object contains encapsulated data and procedures grouped together to represent an entity. The 'object interface' defines how the object can be interacted with. An object-oriented program is described by the interaction of these objects. Object-oriented design is the discipline of defining the objects and their interactions to solve a problem that was identified and documented during object-oriented analysis. What follows is a description of the class-based subset of object-oriented design, which does not include object prototype-based approaches where objects are not typically obtained by instantiating classes but by cloning other (prototype) objects.
Object-oriented design is a method of design encompassing the process of object-oriented decomposition and a notation for depicting both logical and physical as well as state and dynamic models of the system under design. Object-oriented design topics Input (sources) for object-oriented design The input for object-oriented design is provided by the output of object-oriented analysis. Realize that an output artifact does not need to be completely developed to serve as input of object-oriented design; analysis and design may occur in parallel, and in practice the results of one activity can feed the other in a short feedback cycle through an iterative process.
Both analysis and design can be performed incrementally, and the artifacts can be continuously grown instead of completely developed in one shot. Some typical input artifacts for object-oriented design are: Conceptual model: The result of object-oriented analysis, it captures concepts in the problem domain. The conceptual model is explicitly chosen to be independent of implementation details, such as concurrency or data storage. Use case: A description of sequences of events that, taken together, lead to a system doing something useful. Each use case provides one or more scenarios that convey how the system should interact with the users called actors to achieve a specific business goal or function.
Use case actors may be end users or other systems. In many circumstances use cases are further elaborated into use case diagrams. Use case diagrams are used to identify the actor (users or other systems) and the processes they perform. System sequence diagram: A system sequence diagrams (SSD) is a picture that shows, for a particular scenario of a use case, the events that external actors generate, their order, and possible inter-system events. User interface documentations (if applicable): Document that shows and describes the look and feel of the end product's user interface. It is not mandatory to have this, but it helps to visualize the end-product and therefore helps the designer.
Relational data model (if applicable): A data model is an abstract model that describes how data is represented and used. If an object database is not used, the relational data model should usually be created before the design, since the strategy chosen for object-relational mapping is an output of the OO design process. However, it is possible to develop the relational data model and the object-oriented design artifacts in parallel, and the growth of an artifact can stimulate the refinement of other artifacts. Object-oriented concepts The five basic concepts of object-oriented design are the implementation level features that are built into the programming language.
These features are often referred to by these common names: Object/Class: A tight coupling or association of data structures with the methods or functions that act on the data. This is called a class, or object (an object is created based on a class). Each object serves a separate function. It is defined by its properties, what it is and what it can do. An object can be part of a class, which is a set of objects that are similar. Information hiding: The ability to protect some components of the object from external entities. This is realized by language keywords to enable a variable to be declared as private or protected to the owning class.
Inheritance: The ability for a class to extend or override functionality of another class. The so-called subclass has a whole section that is derived (inherited) from the superclass and then it has its own set of functions and data. Interface (object-oriented programming): The ability to defer the implementation of a method. The ability to define the functions or methods signatures without implementing them. Polymorphism (specifically, Subtyping): The ability to replace an object with its subobjects. The ability of an object-variable to contain, not only that object, but also all of its subobjects. Designing concepts Defining objects, creating class diagram from conceptual diagram: Usually map entity to class.
Identifying attributes. Use design patterns (if applicable): A design pattern is not a finished design, it is a description of a solution to a common problem, in a context. The main advantage of using a design pattern is that it can be reused in multiple applications. It can also be thought of as a template for how to solve a problem that can be used in many different situations and/or applications. Object-oriented design patterns typically show relationships and interactions between classes or objects, without specifying the final application classes or objects that are involved. Define application framework (if applicable): Application framework is usually a set of libraries or classes that are used to implement the standard structure of an application for a specific operating system.
By bundling a large amount of reusable code into a framework, much time is saved for the developer, since he/she is saved the task of rewriting large amounts of standard code for each new application that is developed. Identify persistent objects/data (if applicable): Identify objects that have to last longer than a single runtime of the application. If a relational database is used, design the object relation mapping. Identify and define remote objects (if applicable). Output (deliverables) of object-oriented design Sequence diagram: Extend the system sequence diagram to add specific objects that handle the system events. A sequence diagram shows, as parallel vertical lines, different processes or objects that live simultaneously, and, as horizontal arrows, the messages exchanged between them, in the order in which they occur.
Class diagram: A class diagram is a type of static structure UML diagram that describes the structure of a system by showing the system's classes, their attributes, and the relationships between the classes. The messages and classes identified through the development of the sequence diagrams can serve as input to the automatic generation of the global class diagram of the system. Some design principles and strategies Dependency injection: The basic idea is that if an object depends upon having an instance of some other object then the needed object is "injected" into the dependent object; for example, being passed a database connection as an argument to the constructor instead of creating one internally.
Acyclic dependencies principle: The dependency graph of packages or components (the granularity depends on the scope of work for one developer) should have no cycles. This is also referred to as having a directed acyclic graph. For example, package C depends on package B, which depends on package A. If package A also depended on package C, then you would have a cycle. Composite reuse principle: Favor polymorphic composition of objects over inheritance. See also Class-responsibility-collaboration card GRASP (object-oriented design) SOLID IDEF4 Object-oriented analysis Object-oriented programming References External links Object-Oriented Analysis & Design - overview using UML Larman, Craig. Applying UML and Patterns - Third Edition Object-Oriented Analysis and Design LePUS3 and Class-Z: formal modelling languages for object-oriented design Category:Software design Category:Object-oriented programming
The vestibular ganglion (also called Scarpa's ganglion) is the ganglion of the vestibular nerve. It is located inside the internal auditory meatus. The ganglion contains the cell bodies of bipolar neurons whose peripheral processes form synaptic contact with hair cells of the vestibular sensory end organs. These include hair cells of the cristae ampullares of the semicircular duct and macula in the utricle and saccule. It is named for Antonio Scarpa. At birth, it is already close to its final size. References External links Diagram (in French) Histology at wustl.edu Category:Vestibulocochlear nerve Category:Vestibular system
Crinoids are marine animals that make up the class Crinoidea, one of the classes of the phylum Echinodermata, which also includes the starfish, brittle stars, sea urchins and sea cucumbers. Those crinoids which, in their adult form, are attached to the sea bottom by a stalk are commonly called sea lilies, while the unstalked forms are called feather stars or comatulids, being members of the largest crinoid order, Comatulida. Adult crinoids are characterised by having the mouth located on the upper surface. This is surrounded by feeding arms, and is linked to a U-shaped gut, with the anus being located on the oral disc near the mouth.
Although the basic echinoderm pattern of fivefold symmetry can be recognised, in most crinoids the five arms are subdivided into ten or more. These have feathery pinnules and are spread wide to gather planktonic particles from the water. At some stage in their life, most crinoids have a stem used to attach themselves to the substrate, but many live attached only as juveniles and become free-swimming as adults. There are only about 600 living species of crinoid, but the class was much more abundant and diverse in the past. Some thick limestone beds dating to the mid- to late-Paleozoic era are almost entirely made up of disarticulated crinoid fragments.
Etymology The name "Crinoidea" comes from the Greek word κρίνος, "a lily", with the suffix –oid meaning "like". They live in both shallow water and in depths as great as . Those crinoids which in their adult form are attached to the sea bottom by a stalk are commonly called sea lilies. The unstalked forms are called feather stars or comatulids, being members of the largest crinoid order, Comatulida. Morphology The basic body form of a crinoid is a stem (not present in adult feather stars) and a crown consisting of a cup-like central body known as the theca, and a set of five rays or arms, usually branched and feathery.
The mouth and anus are both located on the upper side of the theca, making the dorsal (upper) surface the oral surface, unlike in the other echinoderm groups such as the sea urchins, starfish and brittle stars where the mouth is on the underside. The numerous calcareous plates make up the bulk of the crinoid, with only a small percentage of soft tissue. These ossicles fossilise well and there are beds of limestone dating from the Lower Carboniferous around Clitheroe, England, formed almost exclusively from a diverse fauna of crinoid fossils. The stem of sea lilies is composed of a column of highly porous ossicles which are connected by ligamentary tissue.
It attaches to the substrate with a flattened holdfast or with whorls of jointed, root-like structures known as cirri. Further cirri may occur higher up the stem. In crinoids that attach to hard surfaces, the cirri may be robust and curved, resembling birds' feet, but when crinoids live on soft sediment, the cirri may be slender and rod-like. Juvenile feather stars have a stem, but this is later lost, with many species retaining a few cirri at the base of the crown. The majority of living crinoids are free-swimming and have only a vestigial stalk. In those deep-sea species that still retain a stalk, it may reach up to in length (although usually much smaller), and fossil species are known with stems.
The theca is pentamerous (has five-part symmetry) and is homologous with the body or disc of other echinoderms. The base of the theca is formed from a cup-shaped set of ossicles (bony plates), the calyx, while the upper surface is formed by the weakly-calcified tegmen, a membranous disc. The tegmen is divided into five "ambulacral areas", including a deep groove from which the tube feet project, and five "interambulacral areas" between them. The mouth is near the centre or on the margin of the tegmen, and ambulacral grooves lead from the base of the arms to the mouth. The anus is also located on the tegmen, often on a small elevated cone, in an interambulacral area.
The theca is relatively small and contains the crinoid's digestive organs. The arms are supported by a series of articulating ossicles similar to those in the stalk. Primitively, crinoids had only five arms, but in most modern forms these are divided into two at ossicle II, giving ten arms in total. In most living species, especially the free-swimming feather stars, the arms branch several more times, producing up to two hundred branches in total. Being jointed, the arms can curl up. They are lined, on either side alternately, by smaller jointed appendages known as "pinnules" which give them their feather-like appearance.
Both arms and pinnules have tube feet along the margins of the ambulacral grooves. The tube feet come in groups of three of different size; they have no suction pads and are used to hold and manipulate food particles. The grooves are equipped with cilia which facilitate feeding by moving the organic particles along the arm and into the mouth. Biology Feeding Crinoids are passive suspension feeders, filtering plankton and small particles of detritus from the sea water flowing past them with their feather-like arms. The arms are raised to form a fan-shape which is held perpendicular to the current.
Mobile crinoids move to perch on rocks, coral heads or other eminences to maximise their feeding opportunities. The food particles are caught by the primary (longest) tube feet, which are fully extended and held erect from the pinnules, forming a food-trapping mesh, while the secondary and tertiary tube feet are involved in manipulating anything encountered. The tube feet are covered with sticky mucus that traps any particles which come in contact. Once they have caught a particle of food, the tube feet flick it into the ambulacral groove, where the cilia propel the mucus and food particles towards the mouth.
Lappets at the side of the groove help keep the mucus stream in place. The total length of the food-trapping surface may be very large; the 56 arms of a Japanese sea lily with arms, have a total length of including the pinnules. Generally speaking, crinoids living in environments with relatively little plankton have longer and more highly branched arms than those living in food-rich environments. The mouth descends into a short oesophagus. There is no true stomach, so the oesophagus connects directly to the intestine, which runs in a single loop right around the inside of the calyx. The intestine often includes numerous diverticulae, some of which may be long or branched.
The end of the intestine opens into a short muscular rectum. This ascends towards the anus, which projects from a small conical protuberance at the edge of the tegmen. Faecal matter is formed into large, mucous-cemented pellets which fall onto the tegmen and thence the substrate. Predation Specimens of the sea urchin Calocidaris micans found in the vicinity of the crinoid Endoxocrinus parrae, have been shown to contain large quantities of stem portions in their guts. These consist of articulated ossicles with soft tissue, whereas the local sediment contained only disarticulated ossicles without soft tissue. This makes it highly likely that these sea urchins are predators of the crinoids, and that the crinoids flee, offering part of their stem in the process.
Various crinoid fossils hint at possible prehistoric predators. Coprolites of both fish and cephalopods have been found containing ossicles of various crinoids, such as the pelagic crinoid Saccocoma, from the Jurassic lagerstatten Solnhofen, while damaged crinoid stems with bite marks matching the toothplates of coccosteid placoderms have been found in Late Devonian Poland. The calyxes of several Devonian to Carboniferous-aged crinoids have the shells of a snail, Platyceras, intimately associated with them. Some have the snail situated over the anus, suggesting that Platyceras was a coprophagous commensal, while others have the animal directly situated over a borehole, suggesting a more pernicious relationship.
Water vascular system Like other echinoderms, crinoids possess a water vascular system that maintains hydraulic pressure in the tube feet. This is not connected to external sea water via a madreporite, as in other echinoderms, but only connected through a large number of pores to the coelom (body cavity). The main fluid reservoir is the muscular-walled ring canal which is connected to the coelom by stone canals lined with calcareous material. The coelom is divided into a number of interconnecting spaces by mesenteries. It surrounds the viscera in the disc and has branches within the stalk and arms, with smaller branches extending into the pinnules.
It is the contraction of the ring canal that extends the tube feet. Three narrow branches of the coelom enter each arm, two on the oral side and one aborally, and pinnules. The action of cilia cause there to be a slow flow of fluid (1mm per second) in these canals, outward in the oral branches and inward in the aboral ones, and this is the main means of transport of nutrients and waste products. There is no heart and separate circulatory system but at the base of the disc there is a large blood vessel known as the axial organ, containing some slender blind-ended tubes of unknown function, which extends into the stalk.
These various fluid-filled spaces, in addition to transporting nutrients around the body, also function as both a respiratory and an excretory system. Oxygen is absorbed primarily through the tube feet, which are the most thin-walled parts of the body, with further gas exchange taking place over the large surface area of the arms. There are no specialised organs for excretion while waste is collected by phagocytic coelomocytes. Nervous system The crinoid nervous system is divided into three parts, with numerous connections between them. The oral or uppermost portion is the only one homologous with the nervous systems of other echinoderms.
It consists of a central nerve ring surrounding the mouth, and radial nerves branching into the arms and is sensory in function. Below this lies an intermediate nerve ring, giving off radial nerves supplying the arms and pinnules. These nerves are motor in nature, and control the musculature of the tube feet. The third portion of the nervous system lies aborally, and is responsible for the flexing and movement actions of the arms, pinnules and cirri. This is centred on a mass of neural tissue near the base of the calyx, and provides a single nerve to each arm and a number of nerves to the stalk.
Reproduction and life cycle Crinoids are not capable of clonal reproduction as are some starfish and brittle stars, but are capable of regenerating lost body parts. Arms torn off by predators or damaged by adverse environmental conditions can regrow, and even the visceral mass can regenerate over the course of a few weeks. This regeneration may be vital in surviving attacks by predatory fish. Crinoids are dioecious, with individuals being either male or female. In most species, the gonads are located in the pinnules but in a few, they are located in the arms. Not all the pinnules are reproductive, just those closest to the crown.
The gametes are produced in genital canals enclosed in genital coeloms. The pinnules eventually rupture to release the sperm and eggs into the surrounding sea water. In certain genera, such as Antedon, the fertilised eggs are cemented to the arms with secretions from epidermal glands; in others, especially cold water species from Antarctica, the eggs are brooded in specialised sacs on the arms or pinnules. The fertilised eggs hatch to release free-swimming vitellaria larvae. The bilaterally symmetrical larva is barrel-shaped with rings of cilia running round the body, and a tuft of sensory hairs at the upper pole. While both feeding (planktotrophic) and non-feeding (lecithotrophic) larvae exist among the four other extant echinoderm classes, all present day crinoids appear to be descendants from a surviving clade that went through a bottleneck after the Permian extinction, at that time losing the feeding larval stage.
The larva's free-swimming period lasts for only a few days before it settles on the bottom and attaches itself to the underlying surface using an adhesive gland on its underside. The larva then undergoes an extended period of metamorphoses into a stalked juvenile, becoming radially symmetric in the process. Even the free-swimming feather stars go through this stage, with the adult eventually breaking away from the stalk. Locomotion Most modern crinoids, i.e., the feather stars, are free-moving and lack a stem as adults. Examples of fossil crinoids that have been interpreted as free-swimming include Marsupitsa, Saccocoma and Uintacrinus. In general, crinoids move to new locations by crawling, using the cirri as legs.
Such a movement may be induced in relation to a change in current direction, the need to climb to an elevated perch to feed, or because of an agonistic behaviour by an encountered individual. Crinoids can also swim. They do this by co-ordinated, repeated sequential movements of the arms in three groups. At first the direction of travel is upwards but soon becomes horizontal, travelling at about per second with the oral surface in front. Swimming usually takes place as short bursts of activity lasting up to half a minute, and in the comatulid Florometra serratissima at least, only takes place after mechanical stimulation or as an escape response evoked by a predator.
In 2005, a stalked crinoid was recorded pulling itself along the sea floor off the Grand Bahama Island. While it has been known that stalked crinoids could move, before this recording the fastest motion known for a stalked crinoid was per hour. The 2005 recording showed one of these moving across the seabed at the much faster rate of per second (144 to 180 metres per hour). Evolution Origins If one ignores the enigmatic Echmatocrinus of the Burgess Shale, the earliest known unequivocal crinoid groups date back to the Ordovician, 480 million years ago. There are two competing hypotheses pertaining to the origin of the group: the traditional viewpoint holds that crinoids evolved from within the blastozoans (the eocrinoids and their derived descendants, the blastoids and the cystoids), whereas the most popular alternative suggests that the crinoids split early from among the edrioasteroids.
The debate is difficult to settle, in part because all three candidate ancestors share many characteristics, including radial symmetry, calcareous plates, and stalked or direct attachment to the substrate. Diversity Echinoderms with mineralized skeletons entered the fossil record in the early Cambrian (540 mya), and during the next 100 million years, the crinoids and blastoids (also stalked filter-feeders) were dominant. At that time, the Echinodermata included twenty taxa of class rank, only five of which survived the mass extinction events that followed. The long and varied geological history of the crinoids demonstrates how well the echinoderms had adapted to filter-feeding.
The crinoids underwent two periods of abrupt adaptive radiation, the first during the Ordovician (485 to 444 mya), and the other during the early Triassic (around 230 mya). This Triassic radiation resulted in forms possessing flexible arms becoming widespread; motility, predominantly a response to predation pressure, also became far more prevalent than sessility. This radiation occurred somewhat earlier than the Mesozoic marine revolution, possibly because it was mainly prompted by increases in benthic predation, specifically of echinoids. There then followed a selective mass extinction at the end of the Permian period, during which all blastoids and most crinoids became extinct.