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5,502,804 | https://en.wikipedia.org/wiki/EXI%20Wireless | eXI Wireless is a Canadian business that develops and manufactures Radio Frequency IDentification (RFID) wireless systems. eXI's RFID products include HALO, RoamAlert, and Assetrac. eXI Wireless was acquired by VeriChip Corporation in April 2004.
References
Companies established in 1980
Radio-frequency identification | EXI Wireless | [
"Engineering"
] | 64 | [
"Radio-frequency identification",
"Radio electronics"
] |
5,502,984 | https://en.wikipedia.org/wiki/Carroll%20diagram | A Carroll diagram, Lewis Carroll's square, biliteral diagram or a two-way table is a diagram used for grouping things in a yes/no fashion. Numbers or objects are either categorised as 'x' (having an attribute x) or 'not x' (not having an attribute 'x'). They are named after Lewis Carroll, the pseudonym of polymath Charles Lutwidge Dodgson.
Usage
Although Carroll diagrams can be as simple as the first one above, the most well known types are those similar to the second one, where two attributes are shown. The 'universe' of a Carroll diagram is contained within the boxes in the diagram, as any number or object has to either have an attribute or not have it.
Carroll diagrams are often learnt by schoolchildren, but they can also be used outside the field of education, since they are a tidy way of categorising and displaying information.
See also
Diagram
Karnaugh map
Set theory
Venn diagram
The Game of Logic
References
Further reading
External links
Lewis Carroll: Logic, Internet Encyclopedia of Philosophy
Graphical concepts in set theory
Diagrams
Logical diagrams | Carroll diagram | [
"Mathematics"
] | 233 | [
"Basic concepts in set theory",
"Graphical concepts in set theory"
] |
5,503,004 | https://en.wikipedia.org/wiki/Insulin-like%20growth%20factor%201%20receptor | The insulin-like growth factor 1 (IGF-1) receptor is a protein found on the surface of human cells. It is a transmembrane receptor that is activated by a hormone called insulin-like growth factor 1 (IGF-1) and by a related hormone called IGF-2. It belongs to the large class of tyrosine kinase receptors. This receptor mediates the effects of IGF-1, which is a polypeptide protein hormone similar in molecular structure to insulin. IGF-1 plays an important role in growth and continues to have anabolic effects in adults – meaning that it can induce hypertrophy of skeletal muscle and other target tissues. Mice lacking the IGF-1 receptor die late in development, and show a dramatic reduction in body mass. This testifies to the strong growth-promoting effect of this receptor.
Structure
Two alpha subunits and two beta subunits make up the IGF-1 receptor. Both the α and β subunits are synthesized from a single mRNA precursor. The precursor is then glycosylated, proteolytically cleaved, and crosslinked by cysteine bonds to form a functional transmembrane αβ chain. The α chains are located extracellularly, while the β subunit spans the membrane and is responsible for intracellular signal transduction upon ligand stimulation. The mature IGF-1R has a molecular weight of approximately 320 kDa.citation? The receptor is a member of a family which consists of the insulin receptor and the IGF-2R (and their respective ligands IGF-1 and IGF-2), along with several IGF-binding proteins.
IGF-1R and the insulin receptor both have a binding site for ATP, which is used to provide the phosphates for autophosphorylation. There is a 60% homology between IGF-1R and the insulin receptor. The structures of the autophosphorylation complexes of tyrosine residues 1165 and 1166 have been identified within crystals of the IGF1R kinase domain.
In response to ligand binding, the α chains induce the tyrosine autophosphorylation of the β chains. This event triggers a cascade of intracellular signaling that, while cell type-specific, often promotes cell survival and cell proliferation.
Family members
Tyrosine kinase receptors, including the IGF-1 receptor, mediate their activity by causing the addition of a phosphate groups to particular tyrosines on certain proteins within a cell. This addition of phosphate induces what are called "cell signaling" cascades - and the usual result of activation of the IGF-1 receptor is survival and proliferation in mitosis-competent cells, and growth (hypertrophy) in tissues such as skeletal muscle and cardiac muscle.
Function
Embryonic development
During embryonic development, the IGF-1R pathway is involved with the developing limb buds.
Lactation
The IGFR signalling pathway is of critical importance during normal development of mammary gland tissue during pregnancy and lactation. During pregnancy, there is intense proliferation of epithelial cells which form the duct and gland tissue. Following weaning, the cells undergo apoptosis and all the tissue is destroyed. Several growth factors and hormones are involved in this overall process, and IGF-1R is believed to have roles in the differentiation of the cells and a key role in inhibiting apoptosis until weaning is complete.
Insulin signaling
IGF-1 binds to at least two cell surface receptors: the IGF1 Receptor (IGFR), and the insulin receptor. The IGF-1 receptor seems to be the "physiologic" receptor—it binds IGF-1 at significantly higher affinity than it binds insulin. Like the insulin receptor, the IGF-1 receptor is a receptor tyrosine kinase—meaning it signals by causing the addition of a phosphate molecule on particular tyrosines. IGF-1 activates the insulin receptor at approximately 10% the potency of insulin. Part of this signaling may be via IGF1R/insulin receptor heterodimers (the reason for the confusion is that binding studies show that IGF-1 binds the insulin receptor 100-fold less well than insulin, yet that does not correlate with the actual potency of IGF-1 in vivo at inducing phosphorylation of the insulin receptor, and hypoglycemia).
Aging
Studies in female mice have shown that both supraoptic nucleus (SON) and paraventricular nucleus (PVN) lose approximately one-third of IGF-1R immunoreactive cells with normal aging. Also, old calorically restricted (CR) mice lost higher numbers of IGF-1R non-immunoreactive cells while maintaining similar counts of IGF-1R immunoreactive cells in comparison to old-Al mice. Consequently, old-CR mice show a higher percentage of IGF-1R immunoreactive cells, reflecting increased hypothalamic sensitivity to IGF-1 in comparison to normally aging mice.
Craniosynostosis
Mutations in IGF1R have been associated with craniosynostosis.
Body size
IGF-1R has been shown to have a significant effect on body size in small dog breeds. A "nonsynonymous SNP at chr3:44,706,389 that changes a highly conserved arginine at amino acid 204 to histidine" is associated with particularly tiny body size. "This mutation is predicted to prevent formation of several hydrogen bonds within the cysteine-rich domain of the receptor’s ligand-binding extracellular subunit. Nine of 13 tiny dog breeds carry the mutation and many dogs are homozygous for it." Smaller individuals within several small and medium-sized breeds were shown to carry this mutation as well.
Mice carrying only one functional copy of IGF-1R are normal, but exhibit a ~15% decrease in body mass. IGF-1R has also been shown to regulate body size in dogs. A mutated version of this gene is found in a number of small dog breeds.
Gene inactivation/deletion
Deletion of the IGF-1 receptor gene in mice results in lethality during early embryonic development, and for this reason, IGF-1 insensitivity, unlike the case of growth hormone (GH) insensitivity (Laron syndrome), is not observed in the human population.
Clinical significance
Cancer
The IGF-1R is implicated in several cancers, including breast, prostate, and lung cancers. In some instances its anti-apoptotic properties allow cancerous cells to resist the cytotoxic properties of chemotherapeutic drugs or radiotherapy. In breast cancer, where EGFR inhibitors such as erlotinib are being used to inhibit the EGFR signaling pathway, IGF-1R confers resistance by forming one half of a heterodimer (see the description of EGFR signal transduction in the erlotinib page), allowing EGFR signaling to resume in the presence of a suitable inhibitor. This process is referred to as crosstalk between EGFR and IGF-1R. It is further implicated in breast cancer by increasing the metastatic potential of the original tumour by conferring the ability to promote vascularisation.
Increased levels of the IGF-IR are expressed in the majority of primary and metastatic prostate cancer patient tumors. Evidence suggests that IGF-IR signaling is required for survival and growth when prostate cancer cells progress to androgen independence. In addition, when immortalized prostate cancer cells mimicking advanced disease are treated with the IGF-1R ligand, IGF-1, the cells become more motile.
Members of the IGF receptor family and their ligands also seem to be involved in the carcinogenesis of mammary tumors of dogs. IGF1R is amplified in several cancer types based on analysis of TCGA data, and gene amplification could be one mechanism for overexpression of IGF1R in cancer.
Lung cancer cells stimulated using glucocorticoids were induced into a reversible dormancy state which was dependent on the IGF-1R and its accompanying survival signaling pathways.
Inhibitors
Due to the similarity of the structures of IGF-1R and the insulin receptor (IR), especially in the regions of the ATP binding site and tyrosine kinase regions, synthesising selective inhibitors of IGF-1R is difficult. Prominent in current research are three main classes of inhibitor:
Tyrphostins such as AG538 and AG1024. These are in early pre-clinical testing. They are not thought to be ATP-competitive, although they are when used in EGFR as described in QSAR studies. These show some selectivity towards IGF-1R over IR.
Pyrrolo(2,3-d)-pyrimidine derivatives such as NVP-AEW541, invented by Novartis, which show far greater (100 fold) selectivity towards IGF-1R over IR.
Monoclonal antibodies are probably the most specific and promising therapeutic compounds. Teprotumumab is a novel therapy showing significant benefit for Thyroid Eye Disease.
Interactions
Insulin-like growth factor 1 receptor has been shown to interact with:
ARHGEF12,
C-src tyrosine kinase,
Cbl gene,
EHD1,
GRB10,
IRS1,
Mdm2,
NEDD4,
PIK3R3,
PTPN11,
RAS p21 protein activator 1,
SHC1
SOCS2,
SOCS3, and
YWHAE.
Regulation
There is evidence to suggest that IGF1R is negatively regulated by the microRNA miR-7.
See also
Hypothalamic–pituitary–somatic axis
Insulin receptor
Linsitinib, an inhibitor of IGF-1R in clinical trials for cancer treatment
References
Further reading
External links
Clusters of differentiation
Tyrosine kinase receptors
Integral membrane proteins | Insulin-like growth factor 1 receptor | [
"Chemistry"
] | 2,106 | [
"Tyrosine kinase receptors",
"Signal transduction"
] |
5,503,176 | https://en.wikipedia.org/wiki/Carry%20flag | In computer processors, the carry flag (usually indicated as the C flag) is a single bit in a system status register/flag register used to indicate when an arithmetic carry or borrow has been generated out of the most significant arithmetic logic unit (ALU) bit position. The carry flag enables numbers larger than a single ALU width to be added/subtracted by carrying (adding) a binary digit from a partial addition/subtraction to the least significant bit position of a more significant word. This is typically programmed by the user of the processor on the assembly or machine code level, but can also happen internally in certain processors, via digital logic or microcode, where some processors have wider registers and arithmetic instructions than (combinatorial, or "physical") ALU. It is also used to extend bit shifts and rotates in a similar manner on many processors (sometimes done via a dedicated flag). For subtractive operations, two (opposite) conventions are employed as most machines set the carry flag on borrow while some machines (such as the 6502 and the PIC) instead reset the carry flag on borrow (and vice versa).
Uses
The carry flag is affected by the result of most arithmetic (and typically several bitwise) instructions and is also used as an input to many of them. Several of these instructions have two forms which either read or ignore the carry. In assembly languages these instructions are represented by mnemonics such as ADD/SUB, ADC/SBC (ADD/SUB including carry), SHL/SHR (bit shifts), ROL/ROR (bit rotates), RCR/RCL (rotate through carry), and so on. The use of the carry flag in this manner enables multi-word add, subtract, shift, and rotate operations.
An example is what happens if one were to add 255 and 255 using 8-bit registers. The result should be 510 which is the 9-bit value 111111110 in binary. The 8 least significant bits always stored in the register would be 11111110 binary (254 decimal) but since there is carry out of bit 7 (the eight bit), the carry is set, indicating that the result needs 9 bits. The valid 9-bit result is the concatenation of the carry flag with the result.
For x86 ALU size of 8 bits, an 8-bit two's complement interpretation, the addition operation 11111111 + 11111111 results in 111111110, Carry_Flag set, Sign_Flag set, and Overflow_Flag clear.
If 11111111 represents two's complement signed integer −1 (ADD al,-1), then the interpretation of the result is -2 because Overflow_Flag is clear, and Carry_Flag is ignored. The sign of the result is negative, because Sign_Flag is set. 11111110 is the two's complement form of signed integer −2.
If 11111111 represents unsigned integer binary number 255 (ADD al,255), then the interpretation of the result would be 254, which is not correct, because the most significant bit of the result went into the Carry_Flag, which therefore cannot be ignored. The Overflow_Flag and the Sign_Flag are ignored.
Another example may be an 8-bit register with the bit pattern 01010101 and the carry flag set; if we execute a rotate left through carry instruction, the result would be 10101011 with the carry flag cleared because the most significant bit (bit 7) was rotated into the carry while the carry was rotated into the least significant bit (bit 0).
The early microprocessors Intel 4004 and Intel 8008 had specific instructions to set as well as reset the carry flag explicitly. However, the later Intel 8080 (and Z80) did not include an explicit reset carry opcode as this could be done equally fast via one of the bitwise AND, OR or XOR instructions (which do not use the carry flag).
The carry flag is also often used following comparison instructions, which are typically implemented by subtractive operations, to allow a decision to be made about which of the two compared values is lower than (or greater or equal to) the other. Branch instructions which examine the carry flag are often represented by mnemonics such as BCC and BCS to branch if the carry is clear, or branch if the carry is set respectively. When used in this way the carry flag provides a mechanism for comparing the values as unsigned integers. This is in contrast to the overflow flag which provides a mechanism for comparing the values as signed integer values.
Vs. borrow flag
While the carry flag is well-defined for addition, there are two ways in common use to use the carry flag for subtraction operations.
The first uses the bit as a borrow flag, setting it if a<b when computing a−b, and a borrow must be performed. If a≥b, the bit is cleared. A subtract with borrow (SBB) instruction will compute a−b−C = a−(b+C), while a subtract without borrow (SUB) acts as if the borrow bit were clear. The 6800, 680x0, 8051, 8080/Z80, and x86 families (among others) use a borrow bit.
The second uses the identity that −x = (not x)+1 directly (i.e. without storing the carry bit inverted) and computes a−b as a+(not b)+1. The carry flag is set according to this addition, and subtract with carry computes a+not(b)+C, while subtract without carry acts as if the carry bit were set. The result is that the carry bit is set if a≥b, and clear if a<b. The System/360, ARM, POWER/PowerPC, 6502, MSP430, COP8, Am29000, i960, and 88000 processors use this convention. The 6502 is a particularly well-known example because it does not have a subtract without carry operation, so programmers must ensure that the carry flag is set before every subtract operation where a borrow is not required.
The processors listed above, which include the most popular microprocessors of the last few decades, call these operations "subtract with borrow" and "subtract with carry", respectively, but the nomenclature is far from consistent. The VAX, NS320xx, Fairchild Clipper and Atmel AVR architectures use the borrow bit convention, but call their a−b−C operation "subtract with carry" (SBWC, SUBC, SUBWC and SBC). The PA-RISC and PICmicro architectures use the carry bit convention, but call their a+not(b)+C operation "subtract with borrow" (SUBB and SUBWFB). Still others, such as the H8, call theirs "subtract extended" (SUBX). SPARC uses the borrow convention, the SUBX mnemonic, and the "subtract with carry" name.
The Motorola 6809 uses the borrow bit convention and both nomenclatures, calling the operation "subtract with borrow", but assigning it the mnemonic abbreviation SBC.
The ST6 8-bit microcontrollers go both ways in a different sense. Although they do not have any sort of "subtract with carry" instruction, they do have a carry bit which is set by a subtract instruction, and the convention depends on the processor model. The ST60 processor uses the "carry" convention, while the ST62 and ST63 processors use the "borrow" convention.
See also
Binary arithmetic
Half-carry flag
Status register
References
External links
Carry Flag and Overflow Flag in binary arithmetic
Carry Bit: How does it work?
Computer arithmetic | Carry flag | [
"Mathematics"
] | 1,656 | [
"Computer arithmetic",
"Arithmetic"
] |
5,503,348 | https://en.wikipedia.org/wiki/Negative%20flag | In a computer processor the negative flag or sign flag is a single bit in a system status (flag) register used to indicate whether the result of the last mathematical operation produced a value in which the most significant bit (the left most bit) was set. In a two's complement interpretation of the result, the negative flag is set if the result was negative.
For example, in an 8-bit signed number system, -37 will be represented as 1101 1011 in binary (the most significant bit, or sign bit, is 1), while +37 will be represented as 0010 0101 (the most significant bit is 0).
The negative flag is set according to the result in the x86 series processors by the following instructions (referring to the Intel 80386 manual):
All arithmetic operations except multiplication and division;
compare instructions (equivalent to subtract instructions without storing the result);
Logical instructions – XOR, AND, OR;
TEST instructions (equivalent to AND instructions without storing the result).
References
Computer arithmetic | Negative flag | [
"Mathematics"
] | 212 | [
"Computer arithmetic",
"Arithmetic"
] |
5,503,831 | https://en.wikipedia.org/wiki/Duality%20%28electrical%20circuits%29 | In electrical engineering, electrical terms are associated into pairs called duals. A dual of a relationship is formed by interchanging voltage and current in an expression. The dual expression thus produced is of the same form, and the reason that the dual is always a valid statement can be traced to the duality of electricity and magnetism.
Here is a partial list of electrical dualities:
voltage – current
parallel – series (circuits)
resistance – conductance
voltage division – current division
impedance – admittance
capacitance – inductance
reactance – susceptance
short circuit – open circuit
Kirchhoff's current law – Kirchhoff's voltage law. KVL and KCL
Thévenin's theorem – Norton's theorem
History
The use of duality in circuit theory is due to Alexander Russell who published his ideas in 1904.
Examples
Constitutive relations
Resistor and conductor (Ohm's law)
Capacitor and inductor – differential form
Capacitor and inductor – integral form
Voltage division — current division
Impedance and admittance
Resistor and conductor
Capacitor and inductor
See also
Duality (electricity and magnetism)
Duality (mechanical engineering)
Dual impedance
Dual graph
Mechanical–electrical analogies
List of dualities
References
Turner, Rufus P, Transistors Theory and Practice, Gernsback Library, Inc, New York, 1954, Chapter 6.
Electrical engineering
Electrical circuits | Duality (electrical circuits) | [
"Mathematics",
"Engineering"
] | 296 | [
"Mathematical structures",
"Category theory",
"Duality theories",
"Geometry",
"Electrical engineering"
] |
5,504,424 | https://en.wikipedia.org/wiki/Number%20Forms | Number Forms is a Unicode block containing Unicode compatibility characters that have specific meaning as numbers, but are constructed from other characters. They consist primarily of vulgar fractions and Roman numerals. In addition to the characters in the Number Forms block, three fractions (¼, ½, and ¾) were inherited from ISO-8859-1, which was incorporated whole as the Latin-1 Supplement block.
List of characters
Block
History
The following Unicode-related documents record the purpose and process of defining specific characters in the Number Forms block:
See also
Latin script in Unicode
Unicode symbols
References
Symbols
Unicode
Unicode blocks | Number Forms | [
"Mathematics"
] | 122 | [
"Symbols"
] |
5,504,558 | https://en.wikipedia.org/wiki/Rudolph%20Peters | Sir Rudolph Albert Peters MC MID FRS HFRSE FRCP LLD (13 April 1889 – 29 January 1982) was a British biochemist. He led the research team at Oxford who developed British Anti-Lewisite (BAL), an antidote for the chemical warfare agent lewisite. His efforts investigating the mechanism of arsenic war gases were deemed crucial in maintaining battlefield effectiveness.
Life
He was born in Kensington in London the son of Dr Albert E. D. R. Peters (1863-1945), a physician, and his wife, Agnes Malvina Watts (1867-1950).
He was educated at Wellington College, Berkshire, then studied Medicine at King's College London and Gonville and Caius College, Cambridge.
In the First World War he served in the Royal Army Medical Corps as Medical Officer to the 60th Rifles. From 1917 he was attached to the chemical warfare section at Porton Down. After the war he returned to Cambridge University lecturing in Biochemistry. In 1923 he was created Professor of Biochemistry at Oxford University.
After the Second World War, he researched pyruvate metabolism, focussing particularly on the toxicity of fluoroacetate. The fact that fluoroacetate in itself is far less toxic than its metabolite fluorocitrate led him to coin the term "lethal synthesis" which was the title of his Croonian Lecture of 1951.
Peters retired from academia in 1954 to establish, at age 65, a new department of biochemistry at the Agricultural Research Council Animal Physiology Unit at Babraham; he retired five years later.
He was elected FRS in 1935. In 1940, he received the Cameron Prize for Therapeutics of the University of Edinburgh. He was knighted by Queen Elizabeth II in 1952 and elected an Honorary Fellow of the Royal Society of Edinburgh in 1957.
He died in Cambridge on 29 January 1982, and was cremated there on 4 February.
Some of Sir Rudolph's papers are held at the Bodleian Library.
Family
Peters married Frances Williamina Vérel at the Queen's Park Free Church, Glasgow, on 7 November 1917. Frances was the daughter of Francis William Vérel, a photographic chemist, and had been at school in Westgate-on-Sea with Peters's sister, Gwendoline. They had two sons: Rudolph V (1918-2013), and Francis Raymond (1922-2023).
References
Further reading
1889 births
1982 deaths
People from Kensington
People educated at Wellington College, Berkshire
Alumni of King's College London
Alumni of Gonville and Caius College, Cambridge
Fellows of the Royal Society
Royal Medal winners
British Army personnel of World War I
Royal Army Medical Corps officers
Recipients of the Military Cross
British biochemists
Whitley Professors of Biochemistry
Chemical warfare
Presidents of the Cambridge Philosophical Society | Rudolph Peters | [
"Chemistry"
] | 557 | [
"nan"
] |
5,504,630 | https://en.wikipedia.org/wiki/DNA%20repair-deficiency%20disorder | A DNA repair-deficiency disorder is a medical condition due to reduced functionality of DNA repair.
DNA repair defects can cause an accelerated aging disease or an increased risk of cancer, or sometimes both.
DNA repair defects and accelerated aging
DNA repair defects are seen in nearly all of the diseases described as accelerated aging disease, in which various tissues, organs or systems of the human body age prematurely. Because the accelerated aging diseases display different aspects of aging, but never every aspect, they are often called segmental progerias by biogerontologists.
Human disorders with accelerated aging
Ataxia-telangiectasia
Bloom syndrome
Cockayne syndrome
Fanconi anemia
Progeria (Hutchinson–Gilford progeria syndrome)
Rothmund–Thomson syndrome
Trichothiodystrophy
Werner syndrome
Xeroderma pigmentosum
Examples
Some examples of DNA repair defects causing progeroid syndromes in humans or mice are shown in Table 1.
DNA repair defects distinguished from "accelerated aging"
Most of the DNA repair deficiency diseases show varying degrees of "accelerated aging" or cancer (often some of both). But elimination of any gene essential for base excision repair kills the embryo—it is too lethal to display symptoms (much less symptoms of cancer or "accelerated aging").
Rothmund-Thomson syndrome and xeroderma pigmentosum display symptoms dominated by vulnerability to cancer, whereas progeria and Werner syndrome show the most features of "accelerated aging". Hereditary nonpolyposis colorectal cancer (HNPCC) is very often caused by a defective MSH2 gene leading to defective mismatch repair, but displays no symptoms of "accelerated aging". On the other hand, Cockayne Syndrome and trichothiodystrophy show mainly features of accelerated aging, but apparently without an increased risk of cancer Some DNA repair defects manifest as neurodegeneration rather than as cancer or "accelerated aging". (Also see the "DNA damage theory of aging" for a discussion of the evidence that DNA damage is the primary underlying cause of aging.)
Debate concerning "accelerated aging"
Some biogerontologists question that such a thing as "accelerated aging" actually exists, at least partly on the grounds that all of the so-called accelerated aging diseases are segmental progerias. Many disease conditions such as diabetes, high blood pressure, etc., are associated with increased mortality. Without reliable biomarkers of aging it is hard to support the claim that a disease condition represents more than accelerated mortality.
Against this position other biogerontologists argue that premature aging phenotypes are identifiable symptoms associated with mechanisms of molecular damage. The fact that these phenotypes are widely recognized justifies classification of the relevant diseases as "accelerated aging". Such conditions, it is argued, are readily distinguishable from genetic diseases associated with increased mortality, but not associated with an aging phenotype, such as cystic fibrosis and sickle cell anemia. It is further argued that segmental aging phenotype is a natural part of aging insofar as genetic variation leads to some people being more disposed than others to aging-associated diseases such as cancer and Alzheimer's disease.
DNA repair defects and increased cancer risk
Individuals with an inherited impairment in DNA repair capability are often at increased risk of cancer. When a mutation is present in a DNA repair gene, the repair gene will either not be expressed or be expressed in an altered form. Then the repair function will likely be deficient, and, as a consequence, damages will tend to accumulate. Such DNA damages can cause errors during DNA synthesis leading to mutations, some of which may give rise to cancer. Germ-line DNA repair mutations that increase the risk of cancer are listed in the Table.
See also
Biogerontology
Degenerative disease
DNA damage theory of aging
Genetic disorder
Senescence
References
External links
BRCA - Companion Reviews and Search Terms
BRCA1 - Companion Reviews and Search Terms
BRCA2 - Companion Reviews and Search Terms
ATM - Companion Reviews and Search Terms
NBS1 - Companion Reviews and Search Terms
Bloom s syndrome - Companion Reviews and Search Terms
Fanconi s anemia - Companion Reviews and Search Terms
WRN - Companion Reviews and Search Terms
RECQ- Companion Reviews and Search Terms
RECQL4 - Companion Reviews and Search Terms
FANCJ - Companion Reviews and Search Terms
FANCM - Companion Reviews and Search Terms
FANCN - Companion Reviews and Search Terms
XPB - Companion Reviews and Search Terms
XPD - Companion Reviews and Search Terms
XPG - Companion Reviews and Search Terms
MSH6 - Companion Reviews and Search Terms
MUTYH - Companion Reviews and Search Terms
DNA repair and toxicology - Companion Reviews and Search Terms
Neoplasia inherited - Companion Reviews and Search Terms
Neoplasia carcinogenesis - Companion Reviews and Search Terms
Segmental Progeria
Cancer
DNA repair
Mutation
DNA replication and repair-deficiency disorders
Causes of conditions
Senescence | DNA repair-deficiency disorder | [
"Chemistry",
"Biology"
] | 998 | [
"DNA repair",
"Senescence",
"DNA replication and repair-deficiency disorders",
"Molecular genetics",
"Cellular processes",
"Metabolism"
] |
5,504,687 | https://en.wikipedia.org/wiki/Ionotropic%20glutamate%20receptor | Ionotropic glutamate receptors (iGluRs) are ligand-gated ion channels that are activated by the neurotransmitter glutamate. They mediate the majority of excitatory synaptic transmission throughout the central nervous system and are key players in synaptic plasticity, which is important for learning and memory. iGluRs have been divided into four subtypes on the basis of their ligand binding properties (pharmacology) and sequence similarity: AMPA receptors, kainate receptors, NMDA receptors and delta receptors (see below).
AMPA receptors are the main charge carriers during basal transmission, permitting influx of sodium ions to depolarise the postsynaptic membrane. NMDA receptors are blocked by magnesium ions and therefore only permit ion flux following prior depolarisation. This enables them to act as coincidence detectors for synaptic plasticity. Calcium influx through NMDA receptors leads to persistent modifications in the strength of synaptic transmission.
iGluRs are tetramers (they are formed of four subunits). All subunits have a shared architecture with four domain layers: two extracellular clamshell domains called the N-terminal domain (NTD) and ligand-binding domain (LBD; which binds glutamate), the transmembrane domain (TMD) that forms the ion channel, and an intracellular C-terminal domain (CTD).
Human proteins/genes encoding iGluR subunits
AMPA receptors: GluA1/GRIA1; GluA2/GRIA2; GluA3/GRIA3; GluA4/GRIA4;
delta receptors: GluD1/GRID1; GluD2/GRID2;
kainate receptors: GluK1/GRIK1; GluK2/GRIK2; GluK3/GRIK3; GluK4/GRIK4; GluK5/GRIK5;
NMDA receptors: GluN1/GRIN1; GluN2A/GRIN2A; GluN2B/GRIN2B; GluN2C/GRIN2C; GluN2D/GRIN2D; GluN3A/GRIN3A; GluN3B/GRIN3B;
References
Protein domains
Protein families
Membrane proteins
Ionotropic glutamate receptors | Ionotropic glutamate receptor | [
"Biology"
] | 497 | [
"Protein families",
"Protein domains",
"Protein classification",
"Membrane proteins"
] |
5,504,716 | https://en.wikipedia.org/wiki/Angkasawan%20program | The Angkasawan program was an initiative by the Malaysian government to send a Malaysian to the International Space Station on board Soyuz TMA-11. The program was named after the Malay word for astronaut, Angkasawan. It resulted in Sheikh Muszaphar Shukor becoming the first Malaysian in space on 10 October 2007.
Background and objectives
The program was officially announced by Prime Minister of Malaysia, Mahathir Mohamad, as a joint programme with the Russian Federation. It was a project under the government-to-government offset agreement through the purchase of Sukhoi Su-30MKM fighter jets for the Royal Malaysian Air Force.
Under this agreement the Russian Federation bore the cost of training two Malaysians for space travel and for sending one to the International Space Station (ISS) in October 2007.
The National Space Agency (ANGKASA), Ministry of Science, Technologies and Innovations was given the responsibility of selecting the candidates. Two candidates were then sent to the Cosmonaut Training Programme in Star City, Russia for 18 months of training.
The government set the main objectives of the program as uplifting the national image and instilling in the younger generation greater interest in mathematics and science. At the launch, the Malaysian Science, Technology and Innovation Minister Jamaluddin Jarjis said: "It is not merely a project to send a Malaysian into space. After 50 years of independence, we need a new shift and a new advantage to be more successful as a nation. "We want to awe and inspire, and spur Malaysians to attain greater success by embracing science and technology." The space programme is part of the Ninth Malaysia Plan which also included 217 space science research activities conducted by various universities and agencies in Malaysia.
Later, Jamaluddin Jarjis was more specific as to the objective of the program when he said that it "was to create awareness among Malaysians the importance of science, technology and the space industry, which could help develop the economy further."
Sheikh Muszaphar Shukor himself said that "I am not seeking fame or looking forward to be welcomed like a celebrity, but my quest is to inspire Malaysians, especially schoolchildren to like learning the subject of science and the space industry."
Selection
The four finalists were:
Siva Vanajah, 45
Mohammed Faiz Kamaludin, 44
Faiz Khaleed, 36
Sheikh Muszaphar Shukor, 44
On 23 July 2007, Sheikh Muszaphar participated in a NASA news conference with the Expedition 16 crew. Faiz Khaleed served as backup to Sheikh Muszaphar.
Sheikh Muszaphar Shukor was launched on Soyuz TMA-11 on 10 October 2007 and became the first Malaysian in space. He returned on Soyuz TMA-10 after a ten-day stay on the ISS.
Experiments
On 15 November 2006, in a response to a question in the Dewan Rakyat, Agriculture and Agro-based Industry Ministry parliamentary secretary Rohani Abdul Karim (representing the Science, Technology and Innovation Ministry) stated that the Malaysian astronaut would, "spin top and toss Batu Seremban (five-stone game) as part of an experiment during his space travel". She added, "The astronaut will also paint a batik motif and make "teh tarik" ("pulled" tea) which would be shared with his fellow astronauts.".
However, on 18 December 2006, Science, Technology and Innovation Minister Jamaluddin Jarjis said that making teh-tarik in space would not happen. Various experiments drawn up by selected Malaysian institutes would be carried out by the Malaysian astronaut while in zero-gravity. In the planned physics education (live class in space) portion of the spaceflight, the astronaut will also be, "demonstrating the behaviour of fluids" and "observing the effects of a spinning object", to show Malaysian students on the ground the effects of zero-gravity on selected physical phenomena.
During the mission, Sheikh Muszaphar performed experiments on board the International Space Station relating to the characteristics and growth of liver cancer and leukaemia cells, the crystallisation of various proteins and microbes in space.
The experiments relating to liver cancer, leukaemia cells and microbes were aimed at benefitting general science and medical research, while the experiments relating to the crystallisation of proteins, lipases in this case, were designed to benefit local industries. After the space programme, Malaysia continue to participate in protein research in the Japanese JAXA programme and medical research in Russian MARS-500 programme. Besides, eight patents were filed in Malaysia and abroad. Malaysia also registered a trademark named 1-RAP-NHOst (re-adapted normal human Osteoblast) which has the potential for commercialisation as of 2014.
Criticism
The cost of sending Sheikh Muszaphar into space has been estimated at RM105 million (approximately US$26 million). The Malaysian space program has been criticised as a waste of money for a developing nation that could ill afford such indulgences. Officials defended the funding of the programme as part of a US$900 million defence deal struck with Moscow in 2003 to buy 18 Sukhoi Su-30MKM fighter aircraft. In 2023, Chang Lih Kang clarified that Malaysian government only spent RM 16 million in the programme, including the process of vetting for astronaut candidates, to carry out scientific missions, educational programmes, training at the National Aeronautics and Space Administration (NASA), and insurance for the astronaut. The return on value (ROV) for the government are in the form of knowledge generation, talent development, and knowledge transfer by the experts.
Numerous individuals, especially residents of Malaysia, displayed opposition and ambiguity towards Sheikh Muszaphar's title as a spaceflight participant, citing the fact that he had trained alongside his crew for spaceflight and is fully qualified, arguing that he should be considered an astronaut.
References
External links
Malaysian National Space Agency
Space program of Malaysia
Human spaceflight programs
Malaysia–Russia relations | Angkasawan program | [
"Engineering"
] | 1,219 | [
"Space programs",
"Human spaceflight programs"
] |
5,504,835 | https://en.wikipedia.org/wiki/Medicina%20Radio%20Observatory | The Medicina Radio Observatory is an astronomical observatory located 30 km from Bologna, Italy. It is operated by the Institute for Radio Astronomy of the National Institute for Astrophysics (INAF) of the government of Italy.
The site includes:
32-metre diameter parabolic antenna for observing between 1.4 and 23 GHz. The 32-m antenna is used as a single-dish instrument for astrophysical observations (such as water and methanol maser spectroscopy), SETI experiments and radar monitoring of Near Earth Objects. In interferometric mode it functions as a VLBI station, part of the European VLBI Network (EVN).
564 by 640 m (30000 square meter) multi-element Northern Cross cylindrical-parabolic transit radio telescope for observing at 408 MHz.
Northern Cross Radio Telescope
The Northern Cross Radio Telescope (also known as the Medicina Northern Cross (MNC)) (and Croce del Nord in Italian) is one of the largest transit radio telescopes in the world. Observations are focused around 408 MHz (UHF band), corresponding to 73.5 cm wavelength. The older receivers of the telescope function with a 2.5 MHz wide frequency band, while the upgraded parts have a 16 MHz bandwidth. The telescope is steerable only in declination, meaning that it can solely observe objects that are culminating on the local celestial meridian. The telescope is T-shaped and consists of:
E/W (east–west) arm – Single reflector 35 m (1536 dipoles)
N/S (north–south) arm – Array of 64 reflectors 23.5 m (4096 dipoles)
The telescope can provide 22880 possible theoretical independent beams and has a field of view of 55.47 degrees (east–west) by 1.8 degrees (north–south). The resolution is around 4–5 arcminutes in the north–south direction, and 4 arcminutes in the east–west direction. While less than the resolution of large optical telescopes, the amount of radiation that can be gathered with the Northern Cross is much greater, proportional to the mirror surface of approximately 27400 square meters. Northern Cross represents the largest UHF-band antenna in the Northern hemisphere, with an aperture efficiency of 60%, making it second in the world, after the Arecibo radio telescope. This allows the Northern Cross to identify and measure extremely faint sources, making the telescope is particularly suitable to extragalactic research.
There are plans upgrade of the east–west arm telescope to a LOFAR SuperStation, due to the good performances of a cylindrical-parabolic antenna in the 100–700 MHz frequency range. Since LOFAR operates in the 120–240 MHz range, some of the sensors on the Northern Cross Radio Telescope, optimized for 408 MHz, will have to be replaced with broadband antennas. This installation will have an effective area much larger than any other remote LOFAR station. If extended to the whole 22000 square meters area of the east–west arm, this single element effective area of 20 standard remote LOFAR stations. The resulting system will provide significant improvement in observation sensitivity.
Square Kilometre Array pathfinder
The Cross is currently used as a pathfinder for the Square Kilometre Array. The work is focused on studying the amplification and filtering of signals between the LNA (Low Noise Amplifier) output and the analog-to-digital converter input for the SKA. The Medicina Radio Observatory is studying all problems related to "antenna array implementation" through a prototype installation called MAD (Medicina Array Demonstrator).
The observatory staff have also built new receiver demonstrators for the SKA called BEST (Basic Element for SKA Training), part of the EU-funded SKADS (SKA Design Studies) programme. The project started in 2005 and finished in 2009. It involved the installation of the new receivers on some reflectors of the north–south section (and later east–west section) of the Northern Cross telescope, along with new analog fiber-optic and coaxial digital finks from the front-end receiver boxes to the back-ends. The BEST project was divided in three parts:
BEST-1 – 4 new receivers were installed on a single reflector of the north–south arm.
BEST-2 – 32 receivers were installed on 8 reflectors of the north–south arm.
BEST-3lo focused on lower frequencies – between 120 and 240 MHz. Log periodic antennas optimized for 120–240 MHz, along with 18 receivers were installed on part of the east–west arm.
Space debris tracking
There is an ongoing effort to use the 32-meter dish as a receiver for radar-based tracking of artificial satellites and space debris in Earth orbit. The system functions as a bistatic radar, where an emitter located in a different location sends a signal, which bounces off objects in orbit and the echo is picked up by a receiver. The 32-meter dish acts as a receiver, while usually the Yevpatoria 70 meter located in Crimea, functions as a transmitter. The systems can either actively track debris to determine their orbit more precisely or utilize a technique called beam park, where the transmitting and receiving antennas are kept fixed at a given position and the debris pass in and out of the observed area. The measurements obtain through such a system can be used to determine object radar cross-section, time of peak occurrence, polarization ratio, bistatic doppler shift and target rotation. In one of the carried-out tests, Yevpatoria-Medicina system was able to detect an object with an estimated radar cross-section of 0.0002 square meters, which was created by the Iridium 33 and Kosmos-2251 satellite collision. The system can also function as a multistatic radar using the 32-meter receivers at Medicina, the Noto Radio Observatory in Italy and the Ventspils Starptautiskais Radioastronomijas Centrs in Latvia.
The Northern Cross radio telescope has also been part of space debris tracking studies, utilized as a multiple-beam receiver for a bistatic radar system. The first tested configuration is a quasi-monostatic radar system with a 3 m dish as the transmitter, located in Bagnara – 20 km from the receiver. The second configuration was a simulation of a true bistatic radar system with 7 m dish as the transmitter located at the site of the Sardinia Radio Telescope (SRT). The system has a maximum field-of-view of about 100 square degrees and a collecting area of approximately 27400 square meters and is capable of providing up to 22880 beams, each 4 by 4 arcminutes wide. Tracking the sequence of beams that are illuminated, makes it possible for the system to track with a higher level of detail, with respect to the single-beam systems, the ground track of a transiting object. The Northern Cross radio telescope in a bistatic radar configuration is also part of the Space Surveillance and Tracking (SST) segment of the ESA Space Situational Awareness Programme (SSA).
See also
Istituto di Radioastronomia di Bologna
List of radio telescopes
Noto Radio Observatory
Sardinia Radio Telescope
References
External links
Medicina Radio Astronomical Station website
Older website
Northern Cross website
Radio telescopes
Astronomical observatories in Italy
Buildings and structures in Bologna
Space Situational Awareness Programme
Interferometric telescopes | Medicina Radio Observatory | [
"Environmental_science"
] | 1,507 | [
"Space Situational Awareness Programme"
] |
5,504,842 | https://en.wikipedia.org/wiki/Sense%20%28molecular%20biology%29 | In molecular biology and genetics, the sense of a nucleic acid molecule, particularly of a strand of DNA or RNA, refers to the nature of the roles of the strand and its complement in specifying a sequence of amino acids. Depending on the context, sense may have slightly different meanings. For example, the negative-sense strand of DNA is equivalent to the template strand, whereas the positive-sense strand is the non-template strand whose nucleotide sequence is equivalent to the sequence of the mRNA transcript.
DNA sense
Because of the complementary nature of base-pairing between nucleic acid polymers, a double-stranded DNA molecule will be composed of two strands with sequences that are reverse complements of each other. To help molecular biologists specifically identify each strand individually, the two strands are usually differentiated as the "sense" strand and the "antisense" strand. An individual strand of DNA is referred to as positive-sense (also positive (+) or simply sense) if its nucleotide sequence corresponds directly to the sequence of an RNA transcript which is translated or translatable into a sequence of amino acids (provided that any thymine bases in the DNA sequence are replaced with uracil bases in the RNA sequence). The other strand of the double-stranded DNA molecule is referred to as negative-sense (also negative (−) or antisense), and is reverse complementary to both the positive-sense strand and the RNA transcript. It is actually the antisense strand that is used as the template from which RNA polymerases construct the RNA transcript, but the complementary base-pairing by which nucleic acid polymerization occurs means that the sequence of the RNA transcript will look identical to the positive-sense strand, apart from the RNA transcript's use of uracil instead of thymine.
Sometimes the phrases coding strand and template strand are encountered in place of sense and antisense, respectively, and in the context of a double-stranded DNA molecule the usage of these terms is essentially equivalent. However, the coding/sense strand need not always contain a code that is used to make a protein; both protein-coding and non-coding RNAs may be transcribed.
The terms "sense" and "antisense" are relative only to the particular RNA transcript in question, and not to the DNA strand as a whole. In other words, either DNA strand can serve as the sense or antisense strand. Most organisms with sufficiently large genomes make use of both strands, with each strand functioning as the template strand for different RNA transcripts in different places along the same DNA molecule. In some cases, RNA transcripts can be transcribed in both directions (i.e. on either strand) from a common promoter region, or be transcribed from within introns on either strand (see "ambisense" below).
Sense DNA
The DNA sense strand looks like the messenger RNA (mRNA) transcript, and can therefore be used to read the expected codon sequence that will ultimately be used during translation (protein synthesis) to build an amino acid sequence and then a protein. For example, the sequence "ATG" within a DNA sense strand corresponds to an "AUG" codon in the mRNA, which codes for the amino acid methionine. However, the DNA sense strand itself is not used as the template for the mRNA; it is the DNA antisense strand that serves as the source for the protein code, because, with bases complementary to the DNA sense strand, it is used as a template for the mRNA. Since transcription results in an RNA product complementary to the DNA template strand, the mRNA is complementary to the DNA antisense strand.
Hence, a base triplet 3′-TAC-5′ in the DNA antisense strand (complementary to the 5′-ATG-3′ of the DNA sense strand) is used as the template which results in a 5′-AUG-3′ base triplet in the mRNA. The DNA sense strand will have the triplet ATG, which looks similar to the mRNA triplet AUG but will not be used to make methionine because it will not be directly used to make mRNA. The DNA sense strand is called a "sense" strand not because it will be used to make protein (it won't be), but because it has a sequence that corresponds directly to the RNA codon sequence. By this logic, the RNA transcript itself is sometimes described as "sense".
Example with double-stranded DNA
DNA strand 1: antisense strand (transcribed to) → RNA strand (sense)
DNA strand 2: sense strand
Some regions within a double-stranded DNA molecule code for genes, which are usually instructions specifying the order in which amino acids are assembled to make proteins, as well as regulatory sequences, splicing sites, non-coding introns, and other gene products. For a cell to use this information, one strand of the DNA serves as a template for the synthesis of a complementary strand of RNA. The transcribed DNA strand is called the template strand, with antisense sequence, and the mRNA transcript produced from it is said to be sense sequence (the complement of antisense). The untranscribed DNA strand, complementary to the transcribed strand, is also said to have sense sequence; it has the same sense sequence as the mRNA transcript (though T bases in DNA are substituted with U bases in RNA).
The names assigned to each strand actually depend on which direction you are writing the sequence that contains the information for proteins (the "sense" information), not on which strand is depicted as "on the top" or "on the bottom" (which is arbitrary). The only biological information that is important for labeling strands is the relative locations of the terminal 5′ phosphate group and the terminal 3′ hydroxyl group (at the ends of the strand or sequence in question), because these ends determine the direction of transcription and translation. A sequence written 5′-CGCTAT-3′ is equivalent to a sequence written 3′-TATCGC-5′ as long as the 5′ and 3′ ends are noted. If the ends are not labeled, convention is to assume that both sequences are written in the 5′-to-3′ direction. The "Watson strand" refers to 5′-to-3′ top strand (5′→3′), whereas the "Crick strand" refers to the 5′-to-3′ bottom strand (3′←5′). Both Watson and Crick strands can be either sense or antisense strands depending on the specific gene product made from them.
For example, the notation "YEL021W", an alias of the URA3 gene used in the National Center for Biotechnology Information (NCBI) database, denotes that this gene is in the 21st open reading frame (ORF) from the centromere of the left arm (L) of Yeast (Y) chromosome number V (E), and that the expression coding strand is the Watson strand (W). "YKL074C" denotes the 74th ORF to the left of the centromere of chromosome XI and that the coding strand is the Crick strand (C). Another confusing term referring to "Plus" and "Minus" strand is also widely used. Whether the strand is sense (positive) or antisense (negative), the default query sequence in NCBI BLAST alignment is "Plus" strand.
Ambisense
A single-stranded genome that is used in both positive-sense and negative-sense capacities is said to be ambisense. Some viruses have ambisense genomes. Bunyaviruses have three single-stranded RNA (ssRNA) fragments, some of them containing both positive-sense and negative-sense sections; arenaviruses are also ssRNA viruses with an ambisense genome, as they have three fragments that are mainly negative-sense except for part of the 5′ ends of the large and small segments of their genome.
Antisense RNA
An RNA sequence that is complementary to an endogenous mRNA transcript is sometimes called "antisense RNA". In other words, it is a non-coding strand complementary to the coding sequence of RNA; this is similar to negative-sense viral RNA. When mRNA forms a duplex with a complementary antisense RNA sequence, translation is blocked. This process is related to RNA interference. Cells can produce antisense RNA molecules naturally, called microRNAs, which interact with complementary mRNA molecules and inhibit their expression. The concept has also been exploited as a molecular biology technique, by artificially introducing a transgene coding for antisense RNA in order to block the expression of a gene of interest. Radioactively or fluorescently labelled antisense RNA can be used to show the level of transcription of genes in various cell types.
Some alternative antisense structural types have been experimentally applied as antisense therapy. In the United States, the Food and Drug Administration (FDA) has approved the phosphorothioate antisense oligonucleotides fomivirsen (Vitravene) and mipomersen (Kynamro) for human therapeutic use.
RNA sense in viruses
In virology, the term "sense" has a slightly different meaning. The genome of an RNA virus can be said to be either positive-sense, also known as a "plus-strand", or negative-sense, also known as a "minus-strand". In most cases, the terms "sense" and "strand" are used interchangeably, making terms such as "positive-strand" equivalent to "positive-sense", and "plus-strand" equivalent to "plus-sense". Whether a viral genome is positive-sense or negative-sense can be used as a basis for classifying viruses.
Positive-sense
Positive-sense (5′-to-3′) viral RNA signifies that a particular viral RNA sequence may be directly translated into viral proteins (e.g., those needed for viral replication). Therefore, in positive-sense RNA viruses, the viral RNA genome can be considered viral mRNA, and can be immediately translated by the host cell. Unlike negative-sense RNA, positive-sense RNA is of the same sense as mRNA. Some viruses (e.g. Coronaviridae) have positive-sense genomes that can act as mRNA and be used directly to synthesize proteins without the help of a complementary RNA intermediate. Because of this, these viruses do not need to have an RNA polymerase packaged into the virion—the RNA polymerase will be one of the first proteins produced by the host cell, since it is needed in order for the virus's genome to be replicated.
Negative-sense
Negative-sense (3′-to-5′) viral RNA is complementary to the viral mRNA, thus a positive-sense RNA must be produced by an RNA-dependent RNA polymerase from it prior to translation. Like DNA, negative-sense RNA has a nucleotide sequence complementary to the mRNA that it encodes; also like DNA, this RNA cannot be translated into protein directly. Instead, it must first be transcribed into a positive-sense RNA that acts as an mRNA. Some viruses (e.g. influenza viruses) have negative-sense genomes and so must carry an RNA polymerase inside the virion.
Antisense oligonucleotides
Gene silencing can be achieved by introducing into cells a short "antisense oligonucleotide" that is complementary to an RNA target. This experiment was first done by Zamecnik and Stephenson in 1978 and continues to be a useful approach, both for laboratory experiments and potentially for clinical applications (antisense therapy). Several viruses, such as influenza viruses Respiratory syncytial virus (RSV) and SARS coronavirus (SARS-CoV), have been targeted using antisense oligonucleotides to inhibit their replication in host cells.
If the antisense oligonucleotide contains a stretch of DNA or a DNA mimic (phosphorothioate DNA, 2′F-ANA, or others) it can recruit RNase H to degrade the target RNA. This makes the mechanism of gene silencing catalytic. Double-stranded RNA can also act as a catalytic, enzyme-dependent antisense agent through the RNAi/siRNA pathway, involving target mRNA recognition through sense-antisense strand pairing followed by target mRNA degradation by the RNA-induced silencing complex (RISC). The R1 plasmid hok/sok system provides yet another example of an enzyme-dependent antisense regulation process through enzymatic degradation of the resulting RNA duplex.
Other antisense mechanisms are not enzyme-dependent, but involve steric blocking of their target RNA (e.g. to prevent translation or to induce alternative splicing). Steric blocking antisense mechanisms often use oligonucleotides that are heavily modified. Since there is no need for RNase H recognition, this can include chemistries such as 2′-O-alkyl, peptide nucleic acid (PNA), locked nucleic acid (LNA), and Morpholino oligomers.
See also
Antisense therapy
Directionality (molecular biology)
DNA codon table
RNA virus
Transcription (genetics)
Translation (genetics)
Viral replication
References
DNA
Molecular biology
RNA
Virology | Sense (molecular biology) | [
"Chemistry",
"Biology"
] | 2,778 | [
"Biochemistry",
"Molecular biology"
] |
5,504,984 | https://en.wikipedia.org/wiki/Legal%20year | The legal year, in English law as well as in some other common law jurisdictions, is the calendar during which the judges sit in court. It is traditionally divided into periods called "terms".
Asia
Hong Kong
Hong Kong's legal year is marked as Ceremonial Opening of the Legal Year with an address by the Chief Justice of Hong Kong and begins in January.
Taiwan
The start of the legal year for courts in Taiwan is referred to as Judicial Day and marked in early January.
Europe
England
In England, the year is divided into four terms:
Michaelmas term - from October to December
Hilary term - from January to April
Easter term - from April to May
Trinity term - from June to July.
Between terms, the courts are in vacation, and no trials or appeals are heard in the High Court, Court of Appeal and Supreme Court. The legal terms apply to the High Court, Court of Appeal and Supreme Court only, and so have no application to the Crown Court, County Court, or magistrates' courts. The longest vacation period is between July and October. The dates of the terms are determined in law by a practice direction in the Civil Procedure Rules. The Hilary term was formerly from the 11th to the 31st of January, during which superior courts of
England were open.
The legal year commences at the beginning of October, with a ceremony dating back to the Middle Ages in which the judges arrive in a procession from the Temple Bar to Westminster Abbey for a religious service, followed by a reception known as the Lord Chancellor's breakfast, which is held in Westminster Hall. Although in former times the judges walked the distance from Temple to Westminster, they now mostly arrive by car. The service is held by the Dean of Westminster with the reading performed by the Lord Chancellor.
The ceremony dates back to 1897 and has been held continuously since with the exception of the years 1940 to 1946 because of the Second World War and 2020 because of the COVID-19 pandemic. In 1953 it was held in St Margaret's Church because Westminster Abbey was still decorated for the Coronation of Queen Elizabeth II.
Ireland
In Ireland, the year is divided as per the English system, with identical Michaelmas, Hilary, Easter and Trinity terms. These have a Christmas, Easter, Whit and Long Vacation between them respectively. The Michaelmas term, and legal year, is opened with a service in St. Michan's Church, Dublin attended by members of the Bar and Law Society who then adjourn to a breakfast given in the King's Inns.
France
In France, a rentrée solennelle, a ceremonial sitting of the court, is held in most courts in September to swear in new judges and in January or February, to mark the start of the legal year. New judges may also be sworn in at that event. Bar associations (barreaux), especially larger ones, may also hold a rentrée solennelle, but often at a completely different time of the year to the court-organised official ceremonies, such as in November.
French courts do not sit in a formal term structure, although the practice of vacances judiciaires (legal vacations) between July and the end of August, in late December around Christmas and New Year's and, to a lesser extent, Easter, mean that courts often do not sit to hear non-urgent business during those times, creating, de facto, three legal terms each year.
North America
Canada
Courts in Canada do not have formal terms. They are open year-round but tend to be less busy over the summer months. There is a formal opening of the courts in Ontario in September.
United States
The United States Supreme Court follows part of the legal year tradition, albeit without the elaborate ceremony. The court's year-long term commences on the first Monday in October (and is simply called "October Term"), with a Red Mass the day before. The court then alternates between "sittings" and "recesses" and goes into final recess at the end of June.
Several Midwest and East Coast states and some federal courts still use the legal year and terms of court. Like the Supreme Court, the U.S. Court of Appeals for the Second Circuit has a single year-long term with designated sittings within that term, although the Second Circuit begins its term in August instead of October (hence the name "August Term"). The U.S. Tax Court divides the year into four season-based terms starting in January.
Connecticut appellate courts divide the legal year into eight terms starting in September. New York courts divide the year into 13 terms starting in January. The Georgia Court of Appeals uses a three-term year starting in January. The Illinois Supreme Court divides the year into six terms starting in January.
Several states, like Ohio and Mississippi, do not have a uniform statewide rule for terms of court, so the number of terms varies greatly from one court to the next because every single court sets forth its own terms of court in its local rules.
However, the majority of U.S. states and most federal courts have abandoned the legal year and the related concept of terms of court. Instead, they reverse the presumption. They merely mandate that the courts are to be open year-round during business hours on every day that is not Saturday, Sunday, or a legal holiday. A typical example is Rule 77(c)(1) of the Federal Rules of Civil Procedure, which states that "The clerk's office ... must be open during business hours every day except Saturdays, Sundays, and legal holidays." Furthermore, states: "All courts of the United States shall be deemed always open for the purpose of filing proper papers, issuing and returning process, and making motions and orders."
References
See also
Law Terms Act 1830
Fiscal year
Further reading
External links
The legal year, term dates and sitting days 2024 and 2025 | Courts and Tribunals Judiciary
Practice Direction setting out term dates
English law
Calendars | Legal year | [
"Physics"
] | 1,214 | [
"Spacetime",
"Calendars",
"Physical quantities",
"Time"
] |
5,505,010 | https://en.wikipedia.org/wiki/Ammonium%20alum | Ammonium aluminium sulfate, also known as ammonium alum or just alum (though there are many different substances also called "alum"), is a white crystalline double sulfate usually encountered as the dodecahydrate, formula (NH4)Al(SO4)2·12H2O. It is used in small amounts in a variety of niche applications. The dodecahydrate occurs naturally as the rare mineral tschermigite.
Production and basic properties
Ammonium alum is made from aluminium hydroxide, sulfuric acid and ammonium sulfate. It forms a solid solution with potassium alum. Pyrolysis leaves alumina. Such alumina is used in the production of grinding powders and as precursors to synthetic gems.
Uses
Ammonium alum is not a major industrial chemical or a particularly useful laboratory reagent, but it is cheap and effective, which invites many niche applications. It is used in water purification, in vegetable glues, in porcelain cements, in deodorants and in tanning, dyeing and in fireproofing textiles. The pH of the solution resulting from the topical application of ammonium alum with perspiration is typically in the slightly acid range, from 3 to 5.
Ammonium alum is a common ingredient in animal repellent sprays.
References
Aluminium compounds
Ammonium compounds
Sulfates
Double salts
Astringent flavors
E-number additives | Ammonium alum | [
"Chemistry"
] | 298 | [
"Double salts",
"Sulfates",
"Ammonium compounds",
"Salts"
] |
5,505,240 | https://en.wikipedia.org/wiki/List%20of%20MeSH%20codes%20%28D12.776%29 | The following is a partial list of the "D" codes for Medical Subject Headings (MeSH), as defined by the United States National Library of Medicine (NLM).
This list continues the information at List of MeSH codes (D12.644). Codes following these are found at List of MeSH codes (D13). For other MeSH codes, see List of MeSH codes.
The source for this content is the set of 2006 MeSH Trees from the NLM.
– proteins
– albumins
– c-reactive protein
– conalbumin
– lactalbumin
– ovalbumin
– avidin
– parvalbumins
– ricin
– serum albumin
– methemalbumin
– prealbumin
– serum albumin, bovine
– serum albumin, radio-iodinated
– technetium tc 99m aggregated albumin
– algal proteins
– amphibian proteins
– xenopus proteins
– amyloid
– amyloid beta-protein
– amyloid beta-protein precursor
– serum amyloid a protein
– serum amyloid p-component
– antifreeze proteins
– antifreeze proteins, type i
– antifreeze proteins, type ii
– antifreeze proteins, type iii
– antifreeze proteins, type iv
– apoproteins
– apoenzymes
– apolipoproteins
– apolipoprotein A
– apolipoprotein A1
– apolipoprotein A2
– apolipoprotein B
– apolipoprotein C
– apolipoprotein E
– aprotinin
– archaeal proteins
– bacteriorhodopsins
– dna topoisomerases, type i, archaeal
– halorhodopsins
– periplasmic proteins
– armadillo domain proteins
– beta-catenin
– gamma catenin
– plakophilins
– avian proteins
– bacterial proteins
See List of MeSH codes (D12.776.097).
– blood proteins
See List of MeSH codes (D12.776.124).
– carrier proteins
See List of MeSH codes (D12.776.157).
– cell cycle proteins
– cdc25 phosphatase
– cellular apoptosis susceptibility protein
– cullin proteins
– cyclin-dependent kinase inhibitor proteins
– cyclin-dependent kinase inhibitor p15
– cyclin-dependent kinase inhibitor p16
– cyclin-dependent kinase inhibitor p18
– cyclin-dependent kinase inhibitor p19
– cyclin-dependent kinase inhibitor p21
– cyclin-dependent kinase inhibitor p27
– cyclin-dependent kinase inhibitor p57
– cyclin-dependent kinases
– cdc2-cdc28 kinases
– cdc2 protein kinase
– cdc28 protein kinase, s cerevisiae
– cyclin-dependent kinase 5
– cyclin-dependent kinase 9
– cyclin-dependent kinase 2
– cyclin-dependent kinase 4
– cyclin-dependent kinase 6
– maturation-promoting factor
– cdc2 protein kinase
– cyclins
– cyclin A
– cyclin B
– cyclin D1
– cyclin E
– tumor suppressor protein p14arf
– cerebrospinal fluid proteins
– colipases
– contractile proteins
– muscle proteins
– actinin
– actins
– actomyosin
– calsequestrin
– capz actin capping protein
– caveolin 3
– cofilin 2
– dystrophin
– dystrophin-associated proteins
– dystroglycans
– sarcoglycans
– myogenic regulatory factors
– myod protein
– myogenic regulatory factor 5
– myogenin
– myoglobin
– myosins
– myosin heavy chains
– myosin light chains
– myosin subfragments
– myosin type i
– myosin type ii
– cardiac myosins
– atrial myosins
– ventricular myosins
– nonmuscle myosin type iia
– nonmuscle myosin type iib
– skeletal muscle myosins
– smooth muscle myosins
– parvalbumins
– profilins
– ryanodine receptor calcium release channel
– tropomodulin
– tropomyosin
– troponin
– troponin c
– troponin i
– troponin t
– cystatins
– cytoskeletal proteins
– adenomatous polyposis coli protein
– catenins
– alpha-catenin
– beta catenin
– gamma catenin
– dystrophin
– dystrophin-associated proteins
– dystroglycans
– intermediate filament proteins
– desmin
– glial fibrillary acidic protein
– keratin
– neurofilament proteins
– vimentin
– microfilament proteins
– actin capping proteins
– capz actin capping protein
– tropomodulin
– actin depolymerizing factors
– cofilin 1
– cofilin 2
– destrin
– actin-related protein 2-3 complex
– actin-related protein 2
– actin-related protein 3
– actinin
– actins
– cortactin
– gelsolin
– myosins
– myosin heavy chains
– myosin light chains
– myosin subfragments
– myosin type i
– myosin type ii
– cardiac myosins
– atrial myosins
– ventricular myosins
– nonmuscle myosin type iia
– nonmuscle myosin type iib
– skeletal muscle myosins
– smooth muscle myosins
– myosin type iii
– myosin type iv
– myosin type v
– profilins
– tropomyosin
– troponin
– troponin c
– troponin i
– troponin t
– wiskott-aldrich syndrome protein family
– wiskott-aldrich syndrome protein
– wiskott-aldrich syndrome protein, neuronal
– microtubule proteins
– dynein atpase
– microtubule-associated proteins
– dynamins
– dynamin i
– dynamin ii
– dynamin iii
– kinesin
– stathmin
– tau proteins
– tubulin
– plakins
– desmoplakins
– plectin
– plakophilins
– spectrin
– talin
– utrophin
– vinculin
– dental enamel proteins
– dietary proteins
– egg proteins, dietary
– conalbumin
– ovalbumin
– avidin
– ovomucin
– phosvitin
– milk proteins
– caseins
– lactalbumin
– lactoglobulins
– lactoferrin
– vegetable proteins
– dna-binding proteins
See List of MeSH codes (D12.776.260).
– dynein atpase
– egg proteins
– conalbumin
– egg proteins, dietary
– ovalbumin
– avidin
– ovomucin
– phosvitin
– vitellins
– vitellogenins
– epididymal secretory proteins
– eye proteins
– arrestins
– arrestin
– crystallins
– alpha-crystallins
– alpha-crystallin a chain
– alpha-crystallin b chain
– beta-crystallins
– beta-crystallin a chain
– beta-crystallin b chain
– delta-crystallins
– epsilon-crystallins
– gamma-crystallins
– omega-crystallins
– tau-crystallins
– zeta-crystallins
– guanylate cyclase-activating proteins
– opsin
– rhodopsin
– recoverin
– rhodopsin kinase
– fanconi anemia complementation group proteins
– brca2 protein
– fanconi anemia complementation group a protein
– fanconi anemia complementation group c protein
– fanconi anemia complementation group d2 protein
– fanconi anemia complementation group e protein
– fanconi anemia complementation group f protein
– fanconi anemia complementation group g protein
– fanconi anemia complementation group l protein
– fetal proteins
– alpha-fetoproteins
– fish proteins
– zebrafish proteins
– flavoproteins
– acetolactate synthase
– acyl-coa dehydrogenase
– acyl-coa dehydrogenase, long-chain
– acyl-CoA oxidase
– apoptosis inducing factor
– butyryl-coa dehydrogenase
– cytochrome-b(5) reductase
– dihydrolipoamide dehydrogenase
– electron-transferring flavoproteins
– electron transport complex i
– electron transport complex ii
– succinate dehydrogenase
– flavodoxin
– glutamate synthase (NADH)
– methylenetetrahydrofolate reductase (nadph2)
– nadh dehydrogenase
– nadph oxidase
– nitrate reductase (nadh)
– nitrate reductase (nad(p)h)
– nitrate reductase (nadph)
– retinal dehydrogenase
– sarcosine oxidase
– thioredoxin reductase (nadph)
– fungal proteins
– saccharomyces cerevisiae proteins
– cdc28 protein kinase, s cerevisiae
– cdc42 gtp-binding protein, saccharomyces cerevisiae
– mcm1 protein
– silent information regulator proteins, saccharomyces cerevisiae
– schizosaccharomyces pombe proteins
– globulins
– lactoglobulins
– lactoferrin
– serum globulins
– alpha-globulins
– alpha 1-antichymotrypsin
– alpha 1-antitrypsin
– alpha-macroglobulins
– antiplasmin
– antithrombin iii
– ceruloplasmin
– haptoglobins
– heparin cofactor ii
– orosomucoid
– progesterone-binding globulin
– retinol-binding proteins
– transcortin
– beta-globulins
– beta-2 microglobulin
– beta-thromboglobulin
– complement factor h
– hemopexin
– plasminogen
– angiostatins
– properdin
– sex hormone-binding globulin
– transferrin
– fibronectins
– immunoglobulins
– antibodies
– antibodies, anti-idiotypic
– antibodies, archaeal
– antibodies, bacterial
– antistreptolysin
– antibodies, bispecific
– antibodies, blocking
– antibodies, catalytic
– antibodies, fungal
– antibodies, helminth
– antibodies, heterophile
– antibodies, monoclonal
– muromonab-cd3
– antibodies, neoplasm
– antibodies, phospho-specific
– antibodies, protozoan
– antibodies, viral
– deltaretrovirus antibodies
– hiv antibodies
– htlv-i antibodies
– htlv-ii antibodies
– hepatitis antibodies
– hepatitis a antibodies
– hepatitis b antibodies
– hepatitis c antibodies
– antigen-antibody complex
– antitoxins
– antivenins
– botulinum antitoxin
– diphtheria antitoxin
– tetanus antitoxin
– autoantibodies
– antibodies, antineutrophil cytoplasmic
– antibodies, antinuclear
– antibodies, antiphospholipid
– antibodies, anticardiolipin
– lupus coagulation inhibitor
– complement c3 nephritic factor
– immunoconglutinins
– immunoglobulins, thyroid-stimulating
– long-acting thyroid stimulator
– rheumatoid factor
– binding sites, antibody
– complementarity determining regions
– hemolysins
– immune sera
– antilymphocyte serum
– immunoconjugates
– immunotoxins
– immunoglobulin allotypes
– immunoglobulin gm allotypes
– immunoglobulin km allotypes
– immunoglobulin isotypes
– immunoglobulin a
– immunoglobulin a, secretory
– secretory component
– immunoglobulin alpha-chains
– immunoglobulin d
– immunoglobulin delta-chains
– immunoglobulin e
– immunoglobulin epsilon-chains
– immunoglobulin g
– immunoglobulin gamma-chains
– immunoglobulin gm allotypes
– long-acting thyroid stimulator
– muromonab-cd3
– rho(d) immune globulin
– immunoglobulin m
– immunoglobulin mu-chains
– immunoglobulins, intravenous
– immunoglobulins, thyroid-stimulating
– insulin antibodies
– isoantibodies
– oligoclonal bands
– opsonin proteins
– plantibodies
– precipitins
– reagins
– gamma-globulins
– tuftsin
– immunoglobulin constant regions
– immunoglobulin fab fragments
– immunoglobulin fc fragments
– cd4 immunoadhesins
– immunoglobulin fragments
– immunoglobulin fab fragments
– immunoglobulin variable region
– complementarity determining regions
– immunoglobulin joining region
– tuftsin
– immunoglobulin fc fragments
– cd4 immunoadhesins
– immunoglobulin constant regions
– immunoglobulin idiotypes
– immunoglobulin subunits
– immunoglobulin heavy chains
– immunoglobulin alpha-chains
– immunoglobulin delta-chains
– immunoglobulin epsilon-chains
– immunoglobulin gamma-chains
– immunoglobulin gm allotypes
– immunoglobulin mu-chains
– immunoglobulin j-chains
– immunoglobulin light chains
– immunoglobulin kappa-chains
– immunoglobulin km allotypes
– immunoglobulin lambda-chains
– secretory component
– immunoglobulin variable region
– complementarity determining regions
– immunoglobulin fab fragments
– immunoglobulin joining region
– paraproteins
– bence jones protein
– cryoglobulins
– myeloma proteins
– pyroglobulins
– receptors, antigen, b-cell
– antigens, cd79
– macroglobulins
– alpha-macroglobulins
– transcobalamins
– thyroglobulin
– glycoproteins
See List of MeSH codes (D12.776.395).
– gtp-binding protein regulators
– gtpase-activating proteins
– chimerin proteins
– chimerin 1
– eukaryotic initiation factor-5
– ras gtpase-activating proteins
– neurofibromin 1
– p120 gtpase activating protein
– rgs proteins
– guanine nucleotide dissociation inhibitors
– guanine nucleotide exchange factors
– eukaryotic initiation factor-2b
– guanine nucleotide-releasing factor 2
– proto-oncogene proteins c-vav
– ral guanine nucleotide exchange factor
– ras guanine nucleotide exchange factors
– ras-GRF1
– son of sevenless proteins
– sos1 protein
– son of sevenless protein, drosophila
– heat-shock proteins
– chaperonins
– chaperonin 10
– groes protein
– chaperonin 60
– groel protein
– heat-shock proteins, small
– hsp20 heat-shock proteins
– hsp30 heat-shock proteins
– hsp40 heat-shock proteins
– hsp47 heat-shock proteins
– hsp70 heat-shock proteins
– hsc70 heat-shock proteins
– hsp72 heat-shock proteins
– hsp110 heat-shock proteins
– hsp90 heat-shock proteins
– helminth proteins
– caenorhabditis elegans proteins
– hemeproteins
– cytochromes
– cytochrome a group
– cytochromes a
– cytochromes a1
– cytochromes a3
– cytochrome b group
– cytochromes b6
– cytochromes b
– cytochromes b5
– cytochrome c group
– cytochromes c
– cytochromes c'
– cytochromes c1
– cytochromes c2
– cytochromes c6
– cytochrome d group
– cytochrome p-450 enzyme system
– aryl hydrocarbon hydroxylases
– aniline hydroxylase
– benzopyrene hydroxylase
– cytochrome p-450 cyp1a1
– cytochrome p-450 cyp1a2
– cytochrome p-450 cyp2b1
– cytochrome p-450 cyp2d6
– cytochrome p-450 cyp2e1
– cytochrome p-450 cyp3a
– camphor 5-monooxygenase
– steroid hydroxylases
– aldosterone synthase
– aromatase
– cholesterol 7 alpha-hydroxylase
– cholesterol side-chain cleavage enzyme
– 25-hydroxyvitamin d3 1-alpha-hydroxylase
– steroid 11-beta-hydroxylase
– steroid 12-alpha-hydroxylase
– steroid 16-alpha-hydroxylase
– steroid 17-alpha-hydroxylase
– steroid 21-hydroxylase
– cytochromes f
– hemocyanin
– hemoglobins
– carboxyhemoglobin
– erythrocruorins
– fetal hemoglobin
– hemoglobin A
– hemoglobin a, glycosylated
– hemoglobin A2
– hemoglobins, abnormal
– hemoglobin C
– hemoglobin E
– hemoglobin H
– hemoglobin J
– hemoglobin M
– hemoglobin, sickle
– methemoglobin
– oxyhemoglobins
– sulfhemoglobin
– leghemoglobin
– methemalbumin
– metmyoglobin
– myoglobin
– immediate-early proteins
– adenovirus E1 proteins
– adenovirus E1A proteins
– adenovirus E1B proteins
– butyrate response factor 1
– early growth response transcription factors
– early growth response protein 1
– early growth response protein 2
– early growth response protein 3
– tristetraprolin
– insect proteins
– drosophila proteins
– glue proteins, drosophila
– omega-agatoxin iva
– vitellogenins
– intercellular signaling peptides and proteins
– angiogenic proteins
– angiopoietins
– angiopoietin-1
– angiopoietin-2
– angiostatic proteins
– angiostatins
– endostatins
– vascular endothelial growth factors
– vascular endothelial growth factor a
– vascular endothelial growth factor b
– vascular endothelial growth factor c
– vascular endothelial growth factor d
– vascular endothelial growth factor, endocrine-gland-derived
– bone morphogenetic proteins
– cytokines
– autocrine motility factor
– chemokines
– beta-thromboglobulin
– chemokines, c
– chemokines, cc
– chemokines, cxc
– chemokines, cx3c
– interleukin-8
– macrophage inflammatory proteins
– macrophage inflammatory protein-1
– monocyte chemoattractant proteins
– monocyte chemoattractant protein-1
– platelet factor 4
– rantes
– growth substances
– hematopoietic cell growth factors
– colony-stimulating factors
– colony-stimulating factors, recombinant
– granulocyte colony stimulating factor, recombinant
– filgrastim
– granulocyte macrophage colony-stimulating factors, recombinant
– erythropoietin
– erythropoietin, recombinant
– epoetin alfa
– granulocyte colony-stimulating factor
– granulocyte colony stimulating factor, recombinant
– filgrastim
– granulocyte-macrophage colony-stimulating factor
– granulocyte macrophage colony-stimulating factors, recombinant
– interleukin-3
– macrophage colony-stimulating factor
– thrombopoietin
– stem cell factor
– interleukins
– interleukin-1
– interleukin-2
– interleukin-3
– interleukin-4
– interleukin-5
– interleukin-6
– interleukin-7
– interleukin-8
– interleukin-9
– interleukin-10
– interleukin-11
– interleukin-12
– interleukin-13
– interleukin-14
– interleukin-15
– interleukin-16
– interleukin-17
– interleukin-18
– transforming growth factor beta
– hepatocyte growth factor
– interferons
– interferon type i
– interferon type i, recombinant
– interferon alfa-2a
– interferon alfa-2b
– interferon alfa-2c
– interferon-alpha
– interferon alfa-2a
– interferon alfa-2b
– interferon alfa-2c
– interferon-beta
– interferon type ii
– interferon-gamma, recombinant
– lymphokines
– interferon type ii
– interleukin-2
– leukocyte migration-inhibitory factors
– lymphotoxin
– macrophage-activating factors
– interferon type ii
– macrophage migration-inhibitory factors
– neuroleukin
– suppressor factors, immunologic
– transfer factor
– monokines
– interleukin-1
– tumor necrosis factor-alpha
– tumor necrosis factors
– lymphotoxin
– tumor necrosis factor-alpha
– ephrins
– ephrin-A1
– ephrin-A2
– ephrin-A3
– ephrin-A4
– ephrin-A5
– ephrin-b1
– ephrin-b2
– ephrin-b3
– interferons
– interferon type i
– interferon type i, recombinant
– interferon alfa-2a
– interferon alfa-2b
– interferon alfa-2c
– interferon-alpha
– interferon alfa-2a
– interferon alfa-2b
– interferon alfa-2c
– interferon-beta
– interferon type ii
– interferon-gamma, recombinant
– nerve growth factors
– brain-derived neurotrophic factor
– ciliary neurotrophic factor
– glia maturation factor
– glial cell line-derived neurotrophic factors
– glial cell line-derived neurotrophic factor
– neurturin
– nerve growth factor
– neuregulins
– neuregulin-1
– neurotrophin 3
– pituitary adenylate cyclase-activating polypeptide
– parathyroid hormone-related protein
– semaphorins
– semaphorin-3a
– somatomedins
– insulin-like growth factor i
– insulin-like growth factor ii
– tumor necrosis factors
– lymphotoxin
– tumor necrosis factor-alpha
– wnt proteins
– wnt1 protein
– wnt2 protein
– intracellular signaling peptides and proteins
See List of MeSH codes (D12.776.476).
– iodoproteins
– thyroglobulin
– iron-regulatory proteins
– iron regulatory protein 1
– iron regulatory protein 2
– lectins
– antigens, cd22
– lectins, c-type
– antigens, cd94
– asialoglycoprotein receptor
– collectins
– mannose-binding lectin
– pulmonary surfactant-associated protein a
– pulmonary surfactant-associated protein d
– calnexin
– calreticulin
– galectins
– galectin-1
– galectin-2
– galectin-3
– galectin-4
– mannose-binding lectins
– mannose-binding lectin
– plant lectins
– abrin
– concanavalin a
– peanut agglutinin
– phytohemagglutinins
– pokeweed mitogens
– ricin
– wheat germ agglutinins
– wheat germ agglutinin-horseradish peroxidase conjugate
– receptors, n-acetylglucosamine
– selectins
– e-selectin
– l-selectin
– p-selectin
– lipoproteins
– chromogranins
– chylomicrons
– lipoprotein(a)
– lipoprotein-X
– lipoproteins, hdl
– lipoproteins, hdl cholesterol
– lipoproteins, ldl
– lipoproteins, ldl cholesterol
– lipoproteins, vldl
– lipoproteins, vldl cholesterol
– platelet factor 3
– vitellogenins
– ldl-receptor related proteins
– ldl-receptor related protein 1
– ldl-receptor related protein 2
– lithostathine
– luminescent protein
– aequorin
– green fluorescent protein
– luciferase
– luciferases, bacterial
– Firefly luciferase
– Renilla luciferase
– membrane proteins
See List of MeSH codes (D12.776.543).
– metalloproteins
– azurin
– ceruloplasmin
– hemocyanin
– hemosiderin
– iron-binding proteins
– ferritin
– apoferritin
– lactoferrin
– nonheme iron proteins
– hemerythrin
– inositol oxygenase
– iron-sulfur proteins
– adrenodoxin
– ferredoxin-nitrite reductase
– ferredoxins
– molybdoferredoxin
– rubredoxins
– iron regulatory protein 1
– iron regulatory protein 2
– electron transport complex i
– nadh dehydrogenase
– electron transport complex ii
– succinate dehydrogenase
– electron transport complex iii
– nitrate reductase (nad(p)h)
– nitrate reductase (nadph)
– lipoxygenase
– arachidonate lipoxygenases
– arachidonate 5-lipoxygenase
– arachidonate 12-lipoxygenase
– arachidonate 15-lipoxygenase
– retinal dehydrogenase
– tyrosine 3-monooxygenase
– transferrin
– metallothionein
– plastocyanin
– mitochondrial proteins
– mitochondrial membrane transport proteins
– mitochondrial adp, atp translocases
– adenine nucleotide translocator 1
– adenine nucleotide translocator 2
– adenine nucleotide translocator 3
– molecular chaperones
– alpha-crystallins
– alpha-crystallin a chain
– alpha-crystallin b chain
– chaperonins
– chaperonin 10
– groes protein
– chaperonin 60
– groel protein
– clusterin
– heat-shock proteins, small
– hsp20 heat-shock proteins
– hsp30 heat-shock proteins
– hsp47 heat-shock proteins
– hsp70 heat-shock proteins
– hsc70 heat-shock proteins
– hsp110 heat-shock proteins
– hsp72 heat-shock proteins
– hsp90 heat-shock proteins
– neuroendocrine secretory protein 7b2
– mutant proteins
– mutant chimeric proteins
– oncogene proteins, fusion
– fusion proteins, bcr-abl
– fusion proteins, gag-onc
– oncogene protein p65(gag-jun)
– oncogene protein tpr-met
– neoplasm proteins
– autocrine motility factor
– fusion proteins, bcr-abl
– myeloma proteins
– oncogene proteins
– oncogene proteins, fusion
– fusion proteins, bcr-abl
– fusion proteins, gag-onc
– oncogene protein p65(gag-jun)
– oncogene protein tpr-met
– oncogene proteins, viral
– adenovirus early proteins
– adenovirus E1 proteins
– adenovirus E1A proteins
– adenovirus E1B proteins
– adenovirus e2 proteins
– adenovirus e3 proteins
– adenovirus e4 proteins
– antigens, polyomavirus transforming
– papillomavirus e7 proteins
– retroviridae proteins, oncogenic
– fusion proteins, gag-onc
– oncogene protein p65(gag-jun)
– gene products, rex
– gene products, tax
– oncogene protein gp140(v-fms)
– oncogene protein p21(ras)
– oncogene protein p55(v-myc)
– oncogene protein pp60(v-src)
– oncogene protein v-akt
– oncogene protein v-cbl
– oncogene protein v-crk
– oncogene protein v-maf
– oncogene proteins v-abl
– oncogene proteins v-erba
– oncogene proteins v-erbb
– oncogene proteins v-fos
– oncogene proteins v-mos
– oncogene proteins v-myb
– oncogene proteins v-raf
– oncogene proteins v-rel
– oncogene proteins v-sis
– proto-oncogene proteins
– cyclin d1
– fibroblast growth factor 4
– fibroblast growth factor 6
– fms-like tyrosine kinase 3
– receptor, fibroblast growth factor, type 3
– muts homolog 2 protein
– myeloid-lymphoid leukemia protein
– proto-oncogene proteins c-abl
– proto-oncogene proteins c-akt
– proto-oncogene proteins c-bcl-2
– proto-oncogene proteins c-bcl-6
– proto-oncogene proteins c-bcr
– proto-oncogene proteins c-cbl
– proto-oncogene proteins c-crk
– proto-oncogene proteins c-ets
– proto-oncogene protein c-ets-1
– proto-oncogene protein c-ets-2
– proto-oncogene protein c-fli-1
– ternary complex factors
– ets-domain protein elk-1
– ets-domain protein elk-4
– proto-oncogene proteins c-fes
– proto-oncogene proteins c-fos
– proto-oncogene proteins c-fyn
– proto-oncogene proteins c-hck
– proto-oncogene proteins c-jun
– proto-oncogene proteins c-kit
– proto-oncogene proteins c-maf
– proto-oncogene proteins c-mdm2
– proto-oncogene proteins c-met
– proto-oncogene proteins c-mos
– proto-oncogene proteins c-myb
– proto-oncogene proteins c-myc
– proto-oncogene proteins c-pim-1
– proto-oncogene proteins c-rel
– proto-oncogene proteins c-ret
– proto-oncogene proteins c-sis
– proto-oncogene proteins c-vav
– proto-oncogene proteins c-yes
– proto-oncogene proteins p21(ras)
– proto-oncogene proteins pp60(c-src)
– raf kinases
– proto-oncogene proteins b-raf
– proto-oncogene proteins c-raf
– RNA-binding protein EWS
– lymphocyte specific protein tyrosine kinase p56(lck)
– receptor, erbb-2
– receptor, erbb-3
– receptor, macrophage colony-stimulating factor
– receptors, thyroid hormone
– thyroid hormone receptors alpha
– thyroid hormone receptors beta
– RNA-binding protein FUS
– stathmin
– wnt1 protein
– wnt2 protein
– tumor suppressor proteins
– adenomatous polyposis coli protein
– brca1 protein
– brca2 protein
– cyclin-dependent kinase inhibitor proteins
– cyclin-dependent kinase inhibitor p15
– cyclin-dependent kinase inhibitor p16
– cyclin-dependent kinase inhibitor p18
– cyclin-dependent kinase inhibitor p19
– cyclin-dependent kinase inhibitor p21
– cyclin-dependent kinase inhibitor p27
– cyclin-dependent kinase inhibitor p57
– kangai-1 protein
– neurofibromin 1
– neurofibromin 2
– pten phosphohydrolase
– retinoblastoma-like protein p107
– retinoblastoma-like protein p130
– retinoblastoma protein
– smad4 protein
– tumor suppressor protein p14arf
– tumor suppressor protein p53
– von hippel-lindau tumor suppressor protein
– wt1 proteins
– nerve tissue proteins
See List of MeSH codes (D12.776.641).
– nuclear proteins
See List of MeSH codes (D12.776.660).
– nucleoproteins
– chromatin
– euchromatin
– heterochromatin
– nucleosomes
– chromosomal proteins, non-histone
– centromere protein b
– high mobility group proteins
– hmgn proteins
– hmgn1 protein
– hmgn2 protein
– hmga proteins
– hmga1a protein
– hmga1b protein
– hmga1c protein
– hmga2 protein
– hmgb proteins
– hmgb1 protein
– hmgb2 protein
– hmgb3 protein
– sex-determining region y protein
– tcf transcription factors
– lymphoid enhancer-binding factor 1
– t cell transcription factor 1
– methyl-cpg-binding protein 2
– deoxyribonucleoproteins
– histones
– protamines
– clupeine
– salmine
– RNA-binding proteins
– butyrate response factor 1
– fragile x mental retardation protein
– host factor 1 protein
– hu paraneoplastic encephalomyelitis antigens
– iron regulatory protein 1
– iron regulatory protein 2
– mrna cleavage and polyadenylation factors
– cleavage and polyadenylation specificity factor
– cleavage stimulation factor
– poly(a)-binding proteins
– poly(a)-binding protein i
– poly(a)-binding protein ii
– polypyrimidine tract-binding protein
– ribonucleoproteins
– heterogeneous-nuclear ribonucleoproteins
– RNA-binding protein FUS
– heterogeneous-nuclear ribonucleoprotein group a-b
– heterogeneous-nuclear ribonucleoprotein group c
– heterogeneous-nuclear ribonucleoprotein d
– heterogeneous-nuclear ribonucleoprotein group f-h
– heterogeneous-nuclear ribonucleoprotein k
– heterogeneous-nuclear ribonucleoprotein l
– heterogeneous-nuclear ribonucleoprotein group m
– heterogeneous-nuclear ribonucleoprotein u
– RNA-binding protein EWS
– ribonuclease p
– ribonucleoproteins, small cytoplasmic
– signal recognition particle
– ribonucleoproteins, small nuclear
– ribonucleoproteins, small nucleolar
– ribonucleoprotein, u1 small nuclear
– ribonucleoprotein, u2 small nuclear
– ribonucleoprotein, u4-u6 small nuclear
– ribonucleoprotein, u5 small nuclear
– ribonucleoprotein, u7 small nuclear
– RNA-induced silencing complex
– vault ribonucleoprotein particles
– rna cap-binding proteins
– eukaryotic initiation factor-4f
– nuclear cap-binding protein complex
– oxidative phosphorylation coupling factors
– peptones
– phosphoproteins
– bcl-associated death protein
– brca1 protein
– caseins
– caveolin 1
– caveolin 2
– cdc2 protein kinase
– cortactin
– crk-associated substrate protein
– dopamine and camp-regulated phosphoprotein 32
– fanconi anemia complementation group a protein
– fanconi anemia complementation group d2 protein
– fanconi anemia complementation group g protein
– focal adhesion kinase 1
– interferon regulatory factor-3
– interferon regulatory factor-7
– paxillin
– phosvitin
– plectin
– smad proteins, receptor-regulated
– smad1 protein
– smad2 protein
– smad3 protein
– smad5 protein
– smad8 protein
– retinoblastoma-like protein p107
– retinoblastoma-like protein p130
– retinoblastoma protein
– stathmin
– synapsins
– tumor suppressor protein p53
– vitellogenins
– photoreceptors, microbial
– bacteriochlorophylls
– bacteriochlorophyll a
– rhodopsins, microbial
– bacteriorhodopsins
– halorhodopsins
– sensory rhodopsins
– photosynthetic reaction center complex proteins
– light-harvesting protein complexes
– cytochrome b6f complex
– cytochromes b6
– cytochromes f
– plastoquinol-plastocyanin reductase
– photosystem i protein complex
– photosystem ii protein complex
– plant proteins
– arabidopsis proteins
– agamous protein, arabidopsis
– deficiens protein
– ferredoxins
– g-box binding factors
– gluten
– gliadin
– leghemoglobin
– periplasmic proteins
– phycocyanin
– phycoerythrin
– phytochrome
– phytochrome a
– phytochrome b
– plant lectins
– abrin
– concanavalin a
– peanut agglutinin
– phytohemagglutinins
– pokeweed mitogens
– ricin
– wheat germ agglutinins
– wheat germ agglutinin-horseradish peroxidase conjugate
– plastocyanin
– soybean proteins
– trypsin inhibitor, bowman-birk soybean
– trypsin inhibitor, kunitz soybean
– trichosanthin
– vegetable proteins
– zein
– polyproteins
– gene products, env (gene)
– gene products, gag (gene)
– fusion proteins, gag-pol
– gene products, pol (gene)
– fusion proteins, gag-pol
– pregnancy proteins
– chorionic gonadotropin
– chorionic gonadotropin, beta subunit, human
– gonadotropins, equine
– placental lactogen
– pregnancy-associated alpha 2-macroglobulins
– pregnancy-associated plasma protein-a
– pregnancy-specific beta 1-glycoproteins
– prions
– prpc proteins
– prpsc proteins
– prp 27-30 protein
– protein hydrolysates
– protein isoforms
– isoenzymes
– protein precursors
– amyloid beta-protein precursor
– angiotensinogen
– fibrinogen
– fibrin fibrinogen degradation products
– fibrinopeptide a
– fibrinopeptide b
– glucagon precursors
– kininogens
– kininogen, high-molecular-weight
– kininogen, low-molecular-weight
– procollagen
– proinsulin
– c-peptide
– pro-opiomelanocortin
– tropoelastin
– protein subunits
– proteolipids
– myelin proteolipid protein
– pulmonary surfactant-associated protein c
– proteome
– protozoan proteins
– merozoite surface protein 1
– pulmonary surfactant-associated proteins
– pulmonary surfactant-associated protein a
– pulmonary surfactant-associated protein b
– pulmonary surfactant-associated protein c
– pulmonary surfactant-associated protein d
– receptors, cytoplasmic and nuclear
– hepatocyte nuclear factor 4
– peroxisome proliferator-activated receptors
– PPAR-alpha
– PPAR-beta
– PPAR-delta
– PPAR-gamma
– receptors, aryl hydrocarbon
– receptors, calcitriol
– receptors, melatonin
– receptors, retinoic acid
– Retinoid X receptors
– Retinoid X receptor alpha
– Retinoid X receptor beta
– Retinoid X receptor gamma
– receptors, steroid
– coup transcription factors
– coup transcription factor i
– coup transcription factor ii
– receptors, androgen
– receptors, estrogen
– estrogen receptor alpha
– estrogen receptor beta
– receptors, estradiol
– receptors, glucocorticoid
– receptors, mineralocorticoid
– receptors, aldosterone
– receptors, progesterone
– receptors, thyroid hormone
– thyroid hormone receptors alpha
– thyroid hormone receptors beta
– receptors, drug
– immunophilins
– cyclophilins
– tacrolimus binding proteins
– tacrolimus binding protein 1a
– receptors, phencyclidine
– recombinant proteins
– colony-stimulating factors, recombinant
– granulocyte colony stimulating factor, recombinant
– filgrastim
– granulocyte macrophage colony-stimulating factors, recombinant
– erythropoietin, recombinant
– epoetin alfa
– interferon type i, recombinant
– interferon alfa-2a
– interferon alfa-2b
– interferon alfa-2c
– interferon-gamma, recombinant
– recombinant fusion proteins
– cd4 immunoadhesins
– vaccines, synthetic
– vaccines, dna
– vaccines, edible
– vaccines, virosome
– reptilian proteins
– ribosomal proteins
– peptide elongation factors
– gtp phosphohydrolase-linked elongation factors
– peptide elongation factor g
– peptide elongation factor tu
– peptide elongation factor 1
– peptide elongation factor 2
– peptide initiation factors
– eukaryotic initiation factors
– eukaryotic initiation factor-1
– eukaryotic initiation factor-2
– eukaryotic initiation factor-2b
– eukaryotic initiation factor 3
– eukaryotic initiation factor-4f
– eukaryotic initiation factor-4a
– eukaryotic initiation factor-4e
– Eukaryotic initiation factor 4G
– eukaryotic initiation factor-5
– prokaryotic initiation factors
– prokaryotic initiation factor-1
– prokaryotic initiation factor-2
– prokaryotic initiation factor-3
– peptide termination factors
– ribosomal protein s6
– salivary proteins
(no MeSHNumber) LAPP (leech anti-platelet protein) - presently redirects to LAMP (software bundle) where the term is not mentioned
– glue proteins, drosophila
– scleroproteins
– extracellular matrix proteins
– activated-leukocyte cell adhesion molecule
– collagen
– fibrillar collagens
– Type I collagen
– Type II collagen
– Type III collagen
– Type V collagen
– Type XI collagen
– non-fibrillar collagens
– Type IV collagen
– Type VI collagen
– Type VII collagen
– Type VIII collagen
– Type X collagen
– Type XIII collagen
– Type XVIII collagen
– endostatins
– fibril-associated collagens
– Type IX collagen
– Type XII collagen
– procollagen
– tropocollagen
– elastin
– tropoelastin
– fibronectins
– laminin
– tenascin
– vitronectin
– gelatin
– keratin
– reticulin
– selenium-binding proteins
– selenoproteins
– selenoprotein p
– selenoprotein r
– selenoprotein w
– seminal plasma proteins
– prostatic secretory proteins
– prostate-specific antigen
– seminal vesicle secretory proteins
– serpins
– alpha 1-antichymotrypsin
– alpha 1-antitrypsin
– angiotensinogen
– antiplasmin
– antithrombins
– antithrombin iii
– heparin cofactor ii
– hirudins
– complement c1 inactivator proteins
– hsp47 heat-shock proteins
– ovalbumin
– plasminogen inactivators
– plasminogen activator inhibitor 1
– plasminogen activator inhibitor 2
– protein c inhibitor
– thyroxine-binding proteins
– silk
– fibroins
– sericins
– silver proteins
– thioredoxin
– thymosin
– tissue inhibitor of metalloproteinases
– tissue inhibitor of metalloproteinase-1
– tissue inhibitor of metalloproteinase-2
– tissue inhibitor of metalloproteinase-3
– transcription factors
See List of MeSH codes (D12.776.930).
– ubiquitins
– small ubiquitin-related modifier proteins
– sumo-1 protein
– ubiquitin
– polyubiquitin
– ubiquitin C
– viral proteins
– oncogene proteins, viral
– adenovirus early proteins
– adenovirus e1 proteins
– adenovirus e1a proteins
– adenovirus e1b proteins
– adenovirus e2 proteins
– adenovirus e3 proteins
– adenovirus e4 proteins
– antigens, polyomavirus transforming
– retroviridae proteins, oncogenic
– fusion proteins, gag-onc
– oncogene protein p65(gag-jun)
– gene products, rex
– gene products, tax (gene)
– oncogene protein gp140(v-fms)
– oncogene protein p21(ras)
– oncogene protein p55(v-myc)
– oncogene protein pp60(v-src)
– oncogene protein v-maf
– oncogene proteins v-abl
– oncogene proteins v-erba
– oncogene proteins v-erbb
– oncogene proteins v-fos
– oncogene proteins v-mos
– oncogene proteins v-myb
– oncogene proteins v-raf
– oncogene proteins v-rel
– oncogene proteins v-sis
– retroviridae proteins
– gene products, env (gene)
– hiv envelope protein gp41
– hiv envelope protein gp120
– hiv envelope protein gp160
– gene products, gag (gene)
– fusion proteins, gag-onc
– oncogene protein p65(gag-jun)
– fusion proteins, gag-pol
– hiv core protein p24
– gene products, pol (gene)
– fusion proteins, gag-pol
– hiv integrase
– HIV protease
– RNA-directed DNA polymerase
– hiv-1 reverse transcriptase
– retroviridae proteins, oncogenic
– fusion proteins, gag-onc
– oncogene protein p65(gag-jun)
– gene products, rex
– gene products, tax
– oncogene protein gp140(v-fms)
– oncogene protein p21(ras)
– oncogene protein p55(v-myc)
– oncogene protein pp60(v-src)
– oncogene protein v-maf
– oncogene proteins v-abl
– oncogene proteins v-erba
– oncogene proteins v-erbb
– oncogene proteins v-fos
– oncogene proteins v-mos
– oncogene proteins v-myb
– oncogene proteins v-raf
– oncogene proteins v-rel
– oncogene proteins v-sis
– viral nonstructural proteins
– viral regulatory proteins
– gene products, nef
– gene products, rex
– gene products, vif
– gene products, vpu
– immediate-early proteins
– trans-activators
– gene products, rev (HIV)
– gene products, tat
– gene products, tax
– gene products, vpr
– herpes simplex virus protein vmw65
– viral structural proteins
– nucleocapsid proteins
– capsid proteins
– viral core proteins
– gene products, gag
– fusion proteins, gag-pol
– hiv core protein p24
– gene products, pol (gene)
– fusion proteins, gag-pol
– hiv integrase
– HIV protease
– RNA-directed DNA polymerase
– hiv-1 reverse transcriptase
– viral envelope proteins
– gene products, env
– hiv envelope protein gp41
– hiv envelope protein gp120
– hiv envelope protein gp160
– hemagglutinins, viral
– hemagglutinin glycoproteins, influenza virus
– hn protein
– viral fusion proteins
– hiv envelope protein gp41
– viral matrix proteins
– gene products, vpu
– viral tail proteins
The list continues at List of MeSH codes (D13).
D12.776
Proteins
Protein classification | List of MeSH codes (D12.776) | [
"Chemistry",
"Biology"
] | 10,631 | [
"Biomolecules by chemical classification",
"Proteins",
"Protein classification",
"Molecular biology"
] |
5,505,493 | https://en.wikipedia.org/wiki/Cyclosporins | The cyclosporins are a group of macrolides isolated from fungi and used as immunosuppresant drugs, for example after transplant surgery. They are nonribosomal peptide synthesized by cyclosporin synthetase.
Cyclosporin A (ciclosporin)
Cyclosporin B
Cyclosporin C
Cyclosporin D
Cyclosporin E
Cyclosporin F
Cyclosporin G
References
Cyclic peptides
Immunosuppressants
Fungi and humans | Cyclosporins | [
"Biology"
] | 116 | [
"Fungi and humans",
"Fungi",
"Humans and other species"
] |
5,505,578 | https://en.wikipedia.org/wiki/Recurrent%20point | In mathematics, a recurrent point for a function f is a point that is in its own limit set by f. Any neighborhood containing the recurrent point will also contain (a countable number of) iterates of it as well.
Definition
Let be a Hausdorff space and a function. A point is said to be recurrent (for ) if , i.e. if belongs to its -limit set. This means that for each neighborhood of there exists such that .
The set of recurrent points of is often denoted and is called the recurrent set of . Its closure is called the Birkhoff center of , and appears in the work of George David Birkhoff on dynamical systems.
Every recurrent point is a nonwandering point, hence if is a homeomorphism and is compact, then is an invariant subset of the non-wandering set of (and may be a proper subset).
References
Limit sets | Recurrent point | [
"Mathematics"
] | 194 | [
"Limit sets",
"Topology",
"Topology stubs",
"Dynamical systems"
] |
5,505,849 | https://en.wikipedia.org/wiki/Diphtheria%20toxin | Diphtheria toxin is an exotoxin secreted mainly by Corynebacterium diphtheriae but also by Corynebacterium ulcerans and Corynebacterium pseudotuberculosis, the pathogenic bacterium that causes diphtheria. The toxin gene is encoded by a prophage called corynephage β.
The toxin causes the disease in humans by gaining entry into the cell cytoplasm and inhibiting protein synthesis.
Structure
Diphtheria toxin is a single polypeptide chain of 535 amino acids consisting of two subunits linked by disulfide bridges, known as an A-B toxin. Binding to the cell surface of the B subunit (the less stable of the two subunits) allows the A subunit (the more stable part of the protein) to penetrate the host cell.
The crystal structure of the diphtheria toxin homodimer has been determined to 2.5 Ångstrom resolution. The structure reveals a Y-shaped molecule consisting of three domains. Fragment A contains the catalytic C domain, and fragment B consists of the T and R domains:
The amino-terminal catalytic domain, known as the C domain, has an unusual beta+alpha fold. The C domain blocks protein synthesis by transfer of ADP-ribose from NAD to a diphthamide residue of eukaryotic elongation factor 2 (eEF-2).
A central translocation domain, known as the T domain or TM domain, has a multi-helical globin-like fold with two additional helices at the amino terminus but no counterpart to the first globin helix. This domain is thought to unfold in the membrane. A pH-induced conformational change in the T domain triggers insertion into the endosomal membrane and facilitates the transfer of the C domain into the cytoplasm.
A carboxy-terminal receptor-binding domain, known as the R domain, has a beta-sandwich fold consisting of nine strands in two sheets with Greek-key topology; it is a subclass of immunoglobulin-like fold. The R domain binds to a cell surface receptor, permitting the toxin to enter the cell by receptor-mediated endocytosis.
Mechanism
The diphtheria toxin has the same mechanism of action as the enzyme NAD(+)—diphthamide ADP-ribosyltransferase (). It catalyzes the ADP ribosylation of the unusual amino acid diphthamide in eEF-2 by transferring the ADP-ribosyl group from NAD+. The ADP ribosylation of diphthamide inactivates the eEF-2 protein, thus, inhibiting the translation of mRNA. The catalysed reaction is as follows:
NAD+ + peptide diphthamide nicotinamide + peptide N-(ADP-D-ribosyl)diphthamide.
The exotoxin A of Pseudomonas aeruginosa uses a similar mechanism of action.
The steps involved in generating toxicity are as follows:
Processing
The leader region is cleaved during secretion.
Proteolytic nicking separates A and B subunits, which remain joined by disulfide bonds until they reach the cytosol.
The toxin binds to heparin-binding epidermal growth factor precursor (HB-EGF).
The complex undergoes endocytosis by the host cell.
Acidification inside the endosome induces translocation of the A subunit into the cytosol.
Disulfide bonds are broken.
The B subunit remains in the endosome as a pore.
The A subunit ADP-ribosylates host eEF-2, which is required for protein synthesis; when it is inactivated, the host cannot make protein and thus dies.
Lethal dose and effects
Diphtheria toxin is extraordinarily potent. The lethal dose for humans is about 0.1 μg of toxin per kg of body weight. Death occurs through necrosis of the heart and liver. Diphtheria toxin has also been associated with the development of myocarditis. Myocarditis secondary to diphtheria toxin is considered one of the biggest risks to unimmunized children.
History
Diphtheria toxin was discovered in 1888 by Émile Roux and Alexandre Yersin. In 1890, Emil Adolf von Behring developed an anti-toxin based on the blood of horses immunized with attenuated bacteria. In 1951, Freeman found that the toxin gene was not encoded on the bacterial chromosome, but by a lysogenic phage (corynephage β) infecting all toxigenic strains.
Clinical use
The drug denileukin diftitox uses diphtheria toxin as an antineoplastic agent.
Resimmune is an immunotoxin that is in clinical trials in cutaneous T cell lymphoma patients. It uses diphtheria toxin (truncated by the cell binding domain) coupled to an antibody to CD3ε (UCHT1).
Research
Similar to other A-B toxins, diphtheria toxin is adept at transporting exogenous proteins across mammalian cell membranes, which are usually impermeable to large proteins. This unique ability can be repurposed to deliver therapeutic proteins, instead of the catalytic domain of the toxin.
This toxin has also been used in neuroscientific and cancer research to ablate specific populations of cells which express the diphtheria toxin receptor (heparin-binding EGF-like growth factor). Administration of the toxin into the organism which does not naturally express this receptor (e.g. mice) will result in the selective ablation of the cell population which do express it.
Annotations
References
External links
Hepatotoxins
Protein domains
Peripheral membrane proteins
Bacterial toxins
Toxin
Protein synthesis inhibitors | Diphtheria toxin | [
"Biology"
] | 1,228 | [
"Protein domains",
"Protein classification"
] |
5,506,149 | https://en.wikipedia.org/wiki/Topological%20conjugacy | In mathematics, two functions are said to be topologically conjugate if there exists a homeomorphism that will conjugate the one into the other. Topological conjugacy, and related-but-distinct of flows, are important in the study of iterated functions and more generally dynamical systems, since, if the dynamics of one iterative function can be determined, then that for a topologically conjugate function follows trivially.
To illustrate this directly: suppose that and are iterated functions, and there exists a homeomorphism such that
so that and are topologically conjugate. Then one must have
and so the iterated systems are topologically conjugate as well. Here, denotes function composition.
Definition
, and are continuous functions on topological spaces, and .
being topologically semiconjugate to means, by definition, that is a surjection such that .
and being topologically conjugate means, by definition, that they are topologically semiconjugate and is furthermore injective, then bijective, and its inverse is continuous too; i.e. is a homeomorphism; further, is termed a topological conjugation between and .
Flows
Similarly, on , and on are flows, with , and as above.
being topologically semiconjugate to means, by definition, that is a surjection such that , for each , .
and being topologically conjugate means, by definition, that they are topologically semiconjugate and is a homeomorphism.
Examples
The logistic map and the tent map are topologically conjugate.
The logistic map of unit height and the Bernoulli map are topologically conjugate.
For certain values in the parameter space, the Hénon map when restricted to its Julia set is topologically conjugate or semi-conjugate to the shift map on the space of two-sided sequences in two symbols.
Discussion
Topological conjugation – unlike semiconjugation – defines an equivalence relation in the space of all continuous surjections of a topological space to itself, by declaring and to be related if they are topologically conjugate. This equivalence relation is very useful in the theory of dynamical systems, since each class contains all functions which share the same dynamics from the topological viewpoint. For example, orbits of are mapped to homeomorphic orbits of through the conjugation. Writing makes this fact evident: . Speaking informally, topological conjugation is a "change of coordinates" in the topological sense.
However, the analogous definition for flows is somewhat restrictive. In fact, we are requiring the maps and to be topologically conjugate for each , which is requiring more than simply that orbits of be mapped to orbits of homeomorphically. This motivates the definition of topological equivalence, which also partitions the set of all flows in into classes of flows sharing the same dynamics, again from the topological viewpoint.
Topological equivalence
We say that two flows and are topologically equivalent, if there is a homeomorphism , mapping orbits of to orbits of homeomorphically, and preserving orientation of the orbits. In other words, letting denote an orbit, one has
for each . In addition, one must line up the flow of time: for each , there exists a such that, if , and if is such that , then .
Overall, topological equivalence is a weaker equivalence criterion than topological conjugacy, as it does not require that the time term is mapped along with the orbits and their orientation. An example of a topologically equivalent but not topologically conjugate system would be the non-hyperbolic class of two dimensional systems of differential equations that have closed orbits. While the orbits can be transformed to each other to overlap in the spatial sense, the periods of such systems cannot be analogously matched, thus failing to satisfy the topological conjugacy criterion while satisfying the topological equivalence criterion.
Smooth and orbital equivalence
More equivalence criteria can be studied if the flows, and , arise from differential equations.
Two dynamical systems defined by the differential equations, and , are said to be smoothly equivalent if there is a diffeomorphism, , such that
In that case, the dynamical systems can be transformed into each other by the coordinate transformation, .
Two dynamical systems on the same state space, defined by and , are said to be orbitally equivalent if there is a positive function, , such that . Orbitally equivalent system differ only in the time parametrization.
Systems that are smoothly equivalent or orbitally equivalent are also topologically equivalent. However, the reverse is not true. For example, consider linear systems in two dimensions of the form . If the matrix, , has two positive real eigenvalues, the system has an unstable node; if the matrix has two complex eigenvalues with positive real part, the system has an unstable focus (or spiral). Nodes and foci are topologically equivalent but not orbitally equivalent or smoothly equivalent, because their eigenvalues are different (notice that the Jacobians of two locally smoothly equivalent systems must be similar, so their eigenvalues, as well as algebraic and geometric multiplicities, must be equal).
Generalizations of dynamic topological conjugacy
There are two reported extensions of the concept of dynamic topological conjugacy:
Analogous systems defined as isomorphic dynamical systems
Adjoint dynamical systems defined via adjoint functors and natural equivalences in categorical dynamics.
See also
Commutative diagram
References
Topological dynamics
Homeomorphisms | Topological conjugacy | [
"Mathematics"
] | 1,140 | [
"Topology",
"Homeomorphisms",
"Topological dynamics",
"Dynamical systems"
] |
5,506,202 | https://en.wikipedia.org/wiki/Circular%20folds | The circular folds (also known as valves of Kerckring, valves of Kerchkring, plicae circulares, plicae circulae, and valvulae conniventes) are large valvular flaps projecting into the lumen of the small intestine.
Structure
The entire small intestine has circular folds of mucous membrane. The majority extend transversely around the cylinder of the small intestine, for about one-half or two-thirds of its circumference. Some form complete circles. Others have a spiral direction. The latter usually extend a little more than once around the bowel, but occasionally two or three times. While the larger folds are about 1 cm in depth at their broadest part, most folds are smaller. There tends to be an alternating pattern between larger and smaller folds.
Distribution
They are not found at the commencement of the duodenum, but begin to appear about 2.5 or 5 cm beyond the pylorus.
In the lower part of the descending portion, below the point where the bile and pancreatic ducts enter the small intestine, they are very large and closely approximated.
In the horizontal and ascending portions of the duodenum and upper half of the jejunum, they are large and numerous. From this point, down to the middle of the ileum, they diminish considerably in size.
In the lower part of the ileum, they almost entirely disappear; hence the comparative thinness of this portion of the intestine, as compared with the duodenum and jejunum.
Difference from other gastrointestinal folds
Unlike the gastric folds in the stomach, they are permanent, and are not obliterated when the intestine is distended.
The spaces between circular folds are smaller than the haustra of the colon, and, in contrast to haustra, circular folds reach around the whole circumference of the intestine. These differences can assist in distinguishing the small intestine from the colon on an abdominal x-ray.
Function
The circular folds slow the passage of the partly digested food along the intestines, and afford an increased surface for absorption. They are covered with small finger-like projections called villi (singular, villus). Each villus, in turn, is covered with microvilli. The microvilli absorb fats and nutrients from the chyme.
History
The circular folds are also called the valves of Kerckring, valves of Kerchkring, plicae circulares, plicae circulae, and valvulae conniventes.
References
External links
- "Intestines and Pancreas: The Jejunum and the Ileum"
Digestive system | Circular folds | [
"Biology"
] | 576 | [
"Digestive system",
"Organ systems"
] |
13,312,938 | https://en.wikipedia.org/wiki/Computer-aided%20architectural%20engineering | Computer-aided architectural engineering (CAAE) is the use of information technology for architectural engineering, in tasks such as the analysis, simulation, design, manufacture, planning, diagnosis and repair of architectural structures. CAAE is a subclass of computer-aided engineering. The first Computer-aided architectural design was written by the 1960s. It helped architectures very much that they do not need to draw blueprints. Computer-aided design also known as CAD was the first type of program to help architectures but since it did not have all the features, Computer-aided architectural engineering created as a specific software with all the tools for design.
Overview
All CAAD and CAAE systems use a set of data with geometric and other aspects of an abject; they all use information technology to assembling design from standard or non-standard pieces. For example software like computer animation is what is made in CAAE field. All the blue prints around us is made by CAAE or CAAD software.
Degree
Getting a degree in computer-aided architectural engineering can qualify one for higher-level positions. This specialization is for students interested in having careers in architectural engineering and drafting.a CAAE can have jobs in many areas such as Expeditor, Construction Estimator, Project Manager, project architecture and many other fields related to these.
Advantages
An advantages to CAAE is to develop the two-way mapping software of subject. The two dimension mapping are set to be between the surface structure (TM1) and the deep structure (TM2). In designing the systems, system designers usually pay attention to TM1. The important statement here is a one-to-one mapping, which is to create a computer functionality that maps as close as possible into a resulted manual design project.
An engineer's works mostly involves visually observe data and represent them. Problems are usually outlined and dealt with in graphical result. Therefore, the designer should have a lot control over the processes happens within the design.
See also
Architectural design optimization
Comparison of CAD software
Design computing
References
Computer-aided architectural design
Kalay, Y. (2005). Architecture's New Media. MIT Press, Cambridge, Massachusetts
Architectural design | Computer-aided architectural engineering | [
"Technology",
"Engineering"
] | 444 | [
"Computer engineering",
"Computer engineering stubs",
"Architectural design",
"Computing stubs",
"Design",
"Architecture"
] |
13,313,000 | https://en.wikipedia.org/wiki/Substellar%20object | A substellar object, sometimes called a substar, is an astronomical object, the mass of which is smaller than the smallest mass at which hydrogen fusion can be sustained (approximately 0.08 solar masses). This definition includes brown dwarfs and former stars similar to EF Eridani B, and can also include objects of planetary mass, regardless of their formation mechanism and whether or not they are associated with a primary star.
Assuming that a substellar object has a composition similar to the Sun's and at least the mass of Jupiter (approximately 0.001 solar masses), its radius will be comparable to that of Jupiter (approximately 0.1 solar radii) regardless of the mass of the substellar object (brown dwarfs are less than 75 Jupiter masses). This is because the center of such a substellar object at the top range of the mass (just below the hydrogen-burning limit) is quite degenerate, with a density of ≈103 g/cm3, but this degeneracy lessens with decreasing mass until, at the mass of Jupiter, a substellar object has a central density less than 10 g/cm3. The density decrease balances the mass decrease, keeping the radius approximately constant.
Substellar objects like brown dwarfs do not have enough mass to fuse hydrogen and helium, hence do not undergo the usual stellar evolution that limits the lifetime of stars.
A substellar object with a mass just below the hydrogen-fusing limit may ignite hydrogen fusion temporarily at its center. Although this will provide some energy, it will not be enough to overcome the object's ongoing gravitational contraction. Likewise, although an object with mass above approximately 0.013 solar masses will be able to fuse deuterium for a time, this source of energy will be exhausted in approximately 1100million years. Apart from these sources, the radiation of an isolated substellar object comes only from the release of its gravitational potential energy, which causes it to gradually cool and shrink. A substellar object in orbit around a star will shrink more slowly as it is kept warm by the star, evolving towards an equilibrium state where it emits as much energy as it receives from the star.
Substellar objects are cool enough to have water vapor in their atmosphere. Infrared spectroscopy can detect the distinctive color of water in gas giant size substellar objects, even if they are not in orbit around a star.
Classification
William Duncan MacMillan proposed in 1918 the classification of substellar objects into three categories based on their density and phase state: solid, transitional and dark (non-stellar) gaseous. Solid objects include Earth, smaller terrestrial planets and moons; with Uranus and Neptune (as well as later mini-Neptune and Super Earth planets) as transitional objects between solid and gaseous. Saturn, Jupiter and large gas giant planets are in a fully "gaseous" state.
Substellar companion
A substellar object may be a companion of a star, such as an exoplanet or brown dwarf that is orbiting a star. Objects as low as 823 Jupiter masses have been called substellar companions.
Objects orbiting a star are often called planets below 13 Jupiter masses and brown dwarves above that. Companions at that planet-brown dwarf borderline have been called Super-Jupiters, such as that around the star Kappa Andromedae. Nevertheless, objects as small as 8 Jupiter masses have been called brown dwarfs.
See also
Brown dwarf
List of planet types
Planet
Red dwarf
Sub-brown dwarf
References
Quoted as Chabrier and Baraffe:
External links
Keck views star and companion
Planets
Stars | Substellar object | [
"Astronomy"
] | 725 | [
"Substellar objects",
"Astronomical objects",
"Stars",
"Planets"
] |
13,313,106 | https://en.wikipedia.org/wiki/Astrophysics%20and%20Space%20Science | Astrophysics and Space Science is a bimonthly peer-reviewed scientific journal covering astronomy, astrophysics, and space science and astrophysical aspects of astrobiology. It was established in 1968 and is published by Springer Science+Business Media. From 2016 to 2020, the editors-in-chief were both Prof. Elias Brinks and Prof. Jeremy Mould. Since 2020 the sole editor-in-chief is Prof. Elias Brinks. Other editors-in-chief in the past have been Zdeněk Kopal (Univ. of Manchester) (1968–1993) and Michael A. Dopita (Australian National University) (1994–2015).
Abstracting and indexing
The journal is abstracted and indexed in the following databases:
According to the Journal Citation Reports, the journal has a 2020 impact factor of 1.830.
References
External links
Space science journals
Academic journals established in 1968
Springer Science+Business Media academic journals
Bimonthly journals
Astrophysics journals
English-language journals
Plasma science journals | Astrophysics and Space Science | [
"Physics",
"Astronomy"
] | 205 | [
"Plasma science journals",
"Plasma physics",
"Astronomy stubs",
"Astrophysics journals",
"Astrophysics",
"Astronomy journal stubs"
] |
13,313,715 | https://en.wikipedia.org/wiki/Architectural%20design%20optimization | Architectural design optimization (ADO) is a subfield of engineering that uses optimization methods to study, aid, and solve architectural design problems, such as optimal floorplan layout design, optimal circulation paths between rooms, sustainability and the like. ADO can be achieved through retrofitting, or it can be incorporated within the initial construction a building. Methods of ADO might include the use of metaheuristic, direct search or model-based optimisation. It could also be a more rudimentary process involving identification of a perceived or existing problem with a buildings design in the concept design phase.
Evolution of digital ADO
The origins of digital based methods of ADO can be attributed to the early days of Computer-Aided Design (CAD), a type of software which enabled architects to create, modify and optimise their drafts freely within a digital environment. Although CAD was invented in the early 1960s, with Ivan Sutherland's Sketchpad, its applications predominated the aerospace and automotive industries. It was only until the 1970s that it became of novel use to architects, and only in the 90s did it become widespread within the industry. Programs such as AutoCAD, Rhinoceros and Revit have since assisted architects in the creation of more accurate, more extensively optimised designs by relying on computational power to determine efficient variables in areas of daylighting, energy consumption, circulation and the like. This process has been significantly aided by the integration of black box simulations such as genetic algorithms, which greatly increase the efficacy of ADO when used in conjunction with CAD software. Certain CAD software have begun to implement simulation algorithms natively within their programs. Grasshopper, a virtual programming environment within Rhinoceros 3D, utilises Galapagos as an inbuilt GA.
Methods of ADO
Genetic algorithms
Genetic algorithms (GA) are the most popular form of metaheuristic, black box simulation utilised in the fulfilment of complex ADO. GA emulate the process of biological evolution by engaging in a recursive process of selection or deletion based on a criterion of ‘fitness’. Fitness is determined by how effective or ineffective a solution is at solving a given design problem, such as the optimum angle of windows to achieve daylighting, circulation etc. What differentiates GA from more rudimentary, gradient method simulations is its ability to search for a solution from a population of potential solutions. This multi-directional approach accounts for the often-non-linear nature of architectural design problems by allowing for complex variables from multiple different areas to be incorporated into the optimisation process. The randomised, non-linear characteristics of GA mean they are capable offering solutions to design problems which are, at times, more inventive and unconventional than their search-based counterparts. Due to the complexity of GA simulations, they take a comparatively longer time to perform than other methods. This can be a significant implication to projects operating under time constraints. A study published in 2015 indicated that variations on traditional methods of GA could effectively reduce the processing time of simulations. These included methods of offline simulation and divide and conquer, which utilise architectural domain knowledge to simplify parameters in areas of daylighting and travel distance. This was proposed as one way to increase the accessibility of GA to architects.
Model-based optimisation
Model-based optimisation, unlike metaheuristic and direct search methods, utilises a surrogate model to iteratively refine and optimise architecture. The surrogate model is an explicit representation of implicit mathematical processes, such as statistics or machine learning. Because this method constructs a surrogate model based on an approximation of the underlying simulations, it can be faster to process than alternative methods of black-box optimisation. The efficacy of the surrogate model is determined by the accuracy of the mathematical model. For this reason, some of the time-saving features of model-based optimisation could be invalidated by any additional time spent improving the mathematical functions which regulate the surrogate model. Model based optimisation is advantageous as it enables architects to visually articulate design problems and solutions in real time within design interfaces such as Grasshopper, Rhinoceros 3D, Dynamo BIM and GenerativeComponents.
Direct search
Direct search methods of optimisation operate by selecting parameters in a deterministic sequence, from one point to the next successively until a global optimum is achieved. It is not as ubiquitous a method as genetic algorithms in ADO, but research suggests it outperforms metaheuristic simulations such as GA when improvement attained through each evaluation is measured. There are two types of direct search optimisation, local direct search and global direct search. Single-objective local direct search is one of the earliest and most rudimentary optimisation techniques, but is still utilised in contemporary ADO. Multi-objective global direct search is generally considered to be more effective at solving complex architectural design problems.
Concept design
This method does not rely on computational optimisation, but instead requires the architect to locate areas of optimisation through creative problem solving. This method is limited in its reliance on individual performance and is not likely to yield the most effective optimisation on its own. It could be used in conjunction with optimisation simulations when simulation results are at odds with aesthetic requirements and compromise is necessary. It might also be required when architectural domain knowledge is unknown to the algorithm, and the designer must manually adjust parameters to simplify variables within the simulation.
Performance-based vs performance-driven optimisation
Performance-based and performance-driven optimisation are closely related to each other but vary in how they achieve ADO. The latter concerns itself primarily with the use of computational simulations to optimise based on a set of performance criteria, completing iterations independent from the designer. Performance-based optimisation relies more heavily on the input of the designer to complete iterations. For example, a designer will identify an aspect of a buildings performance that they wish to optimise in the concept design phase and interpret the results of localised simulations to complete iterations manually. This is generally less effective, but also less time-consuming, making it an attractive option for projects operating under time constraints. Certain aspects of a buildings performance which are not readily quantifiable, such as aesthetic and cultural performance, may require alternative methods of optimisation.
Applications of ADO
Sustainability
One potential application of ADO is in the reduction of a building's energy consumption and environmental impact. This might be achieved through the optimisation of the envelope, or façade of a building to ensure ideal thermal properties, which could subsequently reduce the necessity of cooling and heating systems. Other aspects of a buildings form, such as roofing, might be optimised for renewable energy sources. ADO could also assist in the selection of materials that maintain aesthetic and structural qualities, while also being sustainable and of low environmental impact to the surrounding area. Research has shown that ADO can be used jointly with Building Information Modelling (BMI) to ensure the sustainable construction of architecture. This often involves a multi-disciplinary collaboration between architects, structural and mechanical engineers, and consultants. Model-based methods of ADO can be incorporated with BIM to estimate “energy consumption, cost analysis and lifecycle costs” and establish a buildings overall sustainability in relation to each of these criteria. Lifecycle analysis in particular can enable stakeholders to observe the impact of a buildings construction and make prescient decisions regarding its sustainability.
Daylighting
ADO can also be applied to ensure sufficient daylighting within a building. Black box simulations might assist in determining the optimum placement of windows, as well their size, in relation to the building's situation to maximise daylighting. They can similarly determine a floor plan that maximises daylighting from the building's exterior, while concurrently minimising the obstruction of light from interior rooms. Surrogate models, such as those used in model-based optimisation, have proved effective in optimising daylighting through the measurement of Useful Daylight Illuminance (UDI). UDI measures the daylight illuminance within a building based on what is most ‘useful’ to those inhabiting the space. A study measuring the success of optimal UDI in the New Jurong Church building compared optimisation of UDI using both GA and model-based simulations within Grasshopper. It found that RBFOpt, a model-based simulation, produced an objective value of 0.78 while Galapagos, a GA native to Grasshopper, produced a value of 0.05. Research has also indicated a combination of GA and parametric modelling as an effective method of optimising daylight illuminance. Visual comfort (glare) and thermal comfort are other potential applications of ADO to daylighting.
HVAC systems
ADO can help to promote natural as well as man-made ventilation in a buildings design. This might involve establishing wind properties on a building's exterior to ascertain the most efficient method of natural ventilation. In areas where natural ventilation cannot be sufficiently optimised, such as in a buildings substructure, ADO can assist in developing an internal ventilation system that efficiently distributes air. The optimisation of HVAC systems can also allow for a reduction in emissions, which may increase a building's sustainability. Multi-objective simulations have proven capable of achieving this by optimising the insulation and ‘tightness’ of a building to reduce room temperatures and overheating. Evolutionary algorithms such as GA are particularly effective at optimising HVAC due to their multi-directional nature, accounting for interactions that occur between each system and other variables, such as the effects of climate.
Layout design
ADO could be employed to reduce travel time between internal areas of a building through the optimisation of its floor plan layout. Ideal circulation paths within a building might also be attained through the considered placement of stairwells, elevators, and escalators in relation to frequently used amenities. This type of optimisation concerns itself primarily with the spatial configuration of a building, encompassing things such as “component packaging, route path planning, process and facilities layout, VLSI design and architectural layout.” Optimisation of these areas can be broken down further into the binaries of topology and geometry. Topology explores the relationship between structures in a buildings layout while geometry concerns itself more with the placement and dimensions of each structure. Research conducted in 2002 showed that the optimisation of geometry using gradient-based methods yielded successful results, while the optimisation of topology was limited due to the additional complexity of parameters. More recent studies have shown that model-based simulation using parametric modelling is effective at optimising the topology of structural elements outside of layout design, such as the design of truss structures.
Acoustics
The acoustic qualities of a building can be optimised to provide appropriate volume as well as direct sound towards specified areas. The Strait Cultural Center in Fuzhou, China, utilised ADO to optimise the curvature of wall and ceiling structures to facilitate acoustic efficiency. This was achieved through the creation of an iterative model that optimised based on reflection coverage while concurrently reducing unwanted acoustic noise resulting from the shape of the geometry. Norman Foster and Arup similarly utilised ADO in their design of The Greater London Assembly Building, assessing acoustical performance through model-based simulations.
Disadvantages of black box simulations
Due to the complex, time-consuming, computationally demanding and at times restrictive nature of black box simulations, there has been some debate over whether these methods are prohibitive in their practical, everyday use to architects. Architectural firms have been hesitant in the past to employ simulations due to a “lack of pressure/appreciation from the client, high cost of software acquisition and insufficient staff/training skills due to steep learning curves” as well as the absence of user-friendly interfaces. In a survey conducted in 2015, 93% of architects indicated that they would like to better understand the computational principles that underpin optimisation simulations. Other research aimed at addressing this very problem concluded that architects should be educated on the nature of black box simulations and should be able to readily engage with them through an intuitive program that obviates the need for any programming ability. A majority of architects in the survey also indicated a preference for global multi-objective simulations over local, single objective simulations. Multi-objective simulations, such as those that employ GA, solve this problem, but demand significant computational power and time. Research has been conducted to find a viable alternative to GA that exhausts less resources and will be more accessible to architects.
References
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13,313,755 | https://en.wikipedia.org/wiki/SAINT%20%28software%29 | SAINT (Security Administrator's Integrated Network Tool) is computer software used for scanning computer networks for security vulnerabilities, and exploiting found vulnerabilities.
SAINT Network Vulnerability Scanner
The SAINT scanner, screens every live system on a network for TCP and UDP services. For each service it finds running, it launches a set of probes designed to detect anything that could allow an attacker to gain unauthorized access, create a denial-of-service, or gain sensitive information about the network.
SAINT provides support to the Security Content Automation Protocol (SCAP) specification as an Unauthenticated Vulnerability Scanner and Authenticated Vulnerability and Patch Scanner. SAINT is also an approved scanning vendor with the Payment Card Industry (PCI).
The Four Steps of a SAINT Scan:
Step 1 – SAINT screens every live system on a network for TCP and UDP services.
Step 2 – For each service it finds running, it launches a set of probes designed to detect anything that could allow an attacker to gain unauthorized access, create a denial-of-service, or gain sensitive information about the network.
Step 3 – The scanner checks for vulnerabilities.
Step 4 – When vulnerabilities are detected, the results are categorized in several ways, allowing customers to target the data they find most useful.
SAINT can group vulnerabilities according to severity, type, or count. It can also provide information about a particular host or group of hosts. SAINT describes each of the vulnerabilities it locates; references Common Vulnerabilities and Exposures (CVE), CERT advisories, and IAVA (Information Assurance Vulnerability Alerts); and describes ways to correct the vulnerabilities. In many cases, the SAINT scanner provides links to patches or new software versions that will eliminate the detected vulnerabilities.
A vulnerability is a flaw in a system, device, or application that, if leveraged by an attacker, could impact the security of the system. Exploits take advantage of a vulnerability by compromising or destructing the vulnerable system, device, or application. Remediation is the process of repairing or providing a remedy for a vulnerability, thereby eliminating the risk of being exploited. Vulnerability scanning is used to identify and evaluate the security posture of a network. Historically, scanners were developed for specific purposes such as scanning only Windows desktops, applications, or network devices. SAINT offers heterogeneous scanning that identifies vulnerabilities across operating systems, desktop applications, network devices, Web applications, databases, and more.
SAINTexploit Penetration Testing Tool
The integrated penetration testing tool, SAINTexploit, demonstrates the path an attacker could use to breach a network and quantifies the risk to the network. SAINTexploit includes a Web site emulator and e-mail forgery tool.
Penetration testing tools from SAINT are designed to simulate both internal and external real-world attacks. This type of testing identifies the methods of gaining access to a target and understanding the techniques used by attackers. There are many levels and types of penetration testing and the scope of the project should be well defined. Targets included in the scope could include popular protocols, network devices, databases, Web applications, desktop applications, and various flavors of operating systems.
SAINT focuses on the development of exploits where a shell can be established. A shell, or shellcode, is where all exploits included offer a command shell/direct connection to the target from the computer performing the testing. Exploits target operating systems, desktop applications, databases, Web applications, protocols, and network devices. The most common exploit types included in SAINTexploit include the following:
Remote Exploit – These attacks are launched across the Internet or network against a vulnerable target without the user having previous access to the system.
Client Exploit – The victim must access the attacker's resource for a successful attack to take place. Common client exploits include e-mail forgery attacks, enticing the user to visit a Web site, or to open a file.
Local Exploit – In order to launch a local attack, the attacker must have previous access to the victim. (Also known as privilege elevation and tunneling). In this case, the victim's machine is used as the launch pad for connecting to other vulnerable targets.
SAINTmanager Remote Management Console
SAINT's remote management console, SAINTmanager, enables enterprise-wide vulnerability scanning. The browser-based console provides the ability to centrally manage an entire network of SAINT vulnerability scanners from a single interface.
SAINTCloud
SAINTCloud enables cloud based vulnerability scanning, penetration testing, and compliance audits without having to download and install software.
History
The SAINT (Security Administrator's Integrated Network Tool) network vulnerability scanner was based on SATAN (Security Administrator Tool for Analyzing Networks) which was developed by Dan Farmer and Wietse Venema and released in 1995. SAINT Corporation (formerly World Wide Digital Security, Inc. (WWDSI)) continued development and released SAINT in July 1998. WWDSI changed its name to SAINT Corporation in January 2002.
SAINT products are developed by SAINT Corporation, headquartered in Bethesda, Maryland.
References
External links
SAINT home page
Computer security software
Network analyzers | SAINT (software) | [
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13,313,910 | https://en.wikipedia.org/wiki/Sticking%20coefficient | Sticking coefficient is the term used in surface physics to describe the ratio of the number of adsorbate atoms (or molecules) that adsorb, or "stick", to a surface to the total number of atoms that impinge upon that surface during the same period of time. Sometimes the symbol Sc is used to denote this coefficient, and its value is between 1 (all impinging atoms stick) and 0 (no atoms stick). The coefficient is a function of surface temperature, surface coverage (θ) and structural details as well as the kinetic energy of the impinging particles. The original formulation was for molecules adsorbing from the gas phase and the equation was later extended to adsorption from the liquid phase by comparison with molecular dynamics simulations. For use in adsorption from liquids the equation is expressed based on solute density (molecules per volume) rather than the pressure.
Derivation
When arriving at a site of a surface, an adatom has three options. There is a probability that it will adsorb to the surface (), a probability that it will migrate to another site on the surface (), and a probability that it will desorb from the surface and return to the bulk gas (). For an empty site (θ=0) the sum of these three options is unity.
For a site already occupied by an adatom (θ>0), there is no probability of adsorbing, and so the probabilities sum as:
For the first site visited, the P of migrating overall is the P of migrating if the site is filled plus the P of migrating if the site is empty. The same is true for the P of desorption. The P of adsorption, however, does not exist for an already filled site.
The P of migrating from the second site is the P of migrating from the first site and then migrating from the second site, and so we multiply the two values.
Thus the sticking probability () is the P of sticking of the first site, plus the P of migrating from the first site and then sticking to the second site, plus the P of migrating from the second site and then sticking at the third site etc.
There is an identity we can make use of.
The sticking coefficient when the coverage is zero can be obtained by simply setting . We also remember that
If we just look at the P of migration at the first site, we see that it is certainty minus all other possibilities.
Using this result, and rearranging, we find:
References
King-Ning Tu, James W. Mayer, and Leonard C. Feldman, in Electronic Thin Film Science for Electrical Engineers and Materials Scientists, Macmillan, New York, 1992, pp. 101–102.
Surface science
Materials science
Dimensionless numbers of physics | Sticking coefficient | [
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13,314,050 | https://en.wikipedia.org/wiki/Conversation%20theory | Conversation theory is a cybernetic approach to the study of conversation, cognition and learning that may occur between two participants who are engaged in conversation with each other. It presents an experimental framework heavily utilizing human-computer interactions and computer theoretic models as a means to present a scientific theory explaining how conversational interactions lead to the emergence of knowledge between participants. The theory was developed by Gordon Pask, who credits Bernard Scott, Dionysius Kallikourdis, Robin McKinnon-Wood, and others during its initial development and implementation as well as Paul Pangaro during subsequent years.
Overview
Conversation theory may be described as a formal theory of conversational process, as well as a theoretical methodology concerned with concept-forming and concept-sharing between conversational participants. It may be viewed as a framework that may be used to examine learning and development through the means of conversational techniques by means of human-machine interactions; the results of which may then inform approaches to education, educational psychology, and epistemology. While the framework is interpretable as a psychological framework with educational applications (specifically, as a general framework to think about teaching and learning), Pask's motivation in developing the theory has been interpreted by some who closely worked with him develop upon certain theoretical concerns regarding the nature of cybernetic inquiry.
The theory has been noted to have been influenced by a variety of psychological, pedagogical and philosophical influences such as Lev Vygotsky, R. D. Laing and George H. Mead. With some authors suggesting that the kind of human-machine learning interactions documented in conversation theory to be mirroring Vygotsky's descriptions of the zone of proximal development, and his descriptions of spontaneous and scientific concepts.
The theory prioritizes learning and teaching approaches related to education. A central idea of the theory is that learning occurs through conversations: For if participant A is to be conscious with participant B of a topic of inquiry, both participants must be able to converse with each other about that topic. Because of this, participants engaging in a discussion about a subject matter make their knowledge claims explicit through the means of such conversational interactions.
The theory is concerned with a variety of "psychological, linguistic, epistemological, social or non-commitally mental events of which there is awareness". Awareness in this sense is not of a person-specific type, i.e., it is not necessarily localized in a single participant. Instead, the type of awareness examined in conversation theory is the kind of joint awareness that may be shared between entities. While there is an acknowledgment of its similarities to phenomenology, the theory extends its analysis to examine cognitive processes. However, the concept of cognition is not viewed as merely being confined to an individual's brain or central nervous system. Instead, cognition may occur at the level of a group of people (leading to the emergence of social awareness), or may characterize certain types of computing machines.
Initial results from the theory lead to a distinction in the type of learning strategies participants used during the learning process; whereby students in general gravitated towards holistic or serialist learning strategies (with the optimal mixture producing a versatile learning strategy).
Conversation
Following Hugh Dubberly and Paul Pangaro, a conversation in the context of conversation theory involves an exchange between two participants whereby each participant is contextualized as a learning system whose internal states are changed through the course of the conversation. What can be discussed through conversation, i.e., topics of discussion, are said to belong to a conversational domain.
Conversation is distinguished from the mere exchange of information as seen in information theory, by the fact that utterances are interpreted within the context of a given perspective of such a learning system. Each participant's meanings and perceptions change during the course of a conversation, and each participant can agree to commit to act in certain ways during the conversation. In this way, conversation permits not only learning but also collaboration through participants coordinating themselves and designating their roles through the means of conversation.
Since meanings are agreed during the course of a conversation, and since purported agreements can be illusory (whereby we think we have the same understanding of a given topic but in fact do not), an empirical approach to the study of conversation would require stable reference points during such conversational exchanges between peers so as to permit reproducible results. Using computer theoretical models of cognition, conversation theory can document these intervals of understanding that arise in the conversations between two participating individuals, such that the development of individual and collective understandings can be analyzed rigorously.
In this way, Pask has been argued to have been an early pioneer in AI-based educational approaches: Having proposed that advances in computational media may enable conversational forms of interactions to take place between man and machine.
Language
The types of languages that conversation theory utilizes in its approach are distinguishable based on a language's role in relation to an experiment in which a conversation is examined as the subject of inquiry; thus, it follows that conversations can be conducted at different levels depending on the role a language has in relation to an experiment. The types of languages are as follows: Natural languages used for general discussions outside the experiment; object languages which are the subject of inquiry during an experiment, and finally a metalanguage which is used to talk about the design, management, and results on an experiment.
A natural language is treated as an unrestricted language used between a source (say a participant) and an interrogator or analyst (say an experimenter).
For this reason, it may be considered a language for general discussion in the context of conversation theory.
An object language meanwhile, has some of the qualities of a natural language (which permits commands, questions, ostentation and predication), but is used in conversation theory specifically as the language studied during experiments. Finally, the metalanguage is an observational language used by an interrogator or analysis for describing the conversational system under observation, prescribing actions that are permitted within such a system, and posing parameters regarding what may be discussed during an experiment under observation.
The object language differs from most formal languages, by virtue of being "a command and question language[,] not an assertoric language like [a] predicate calculus". Moreover, is a language primarily dealing with metaphors indicating material analogies and not on the kind of propositions dealing with truth or falsity values. Since conversation theory specifically focuses on learning and development within human subjects, the object language is separated into two distinct modes of conversing.
Conversation theory conceptualises learning as being the result of two integrated levels of control: The first level of control is designated by and designates a set of problem-solving procedures which attempt to attain goals or subgoals, whereas the second level of control is designated as and denotes various constructive processes that have been acquired by a student through maturation, imprinting and previous learning.
The object language then is demarcated in conversation theory based on these considerations, whereby it is split between and lines of inquiry such that an object language is the ordered pair of such discourse types .
According to Bernard Scott, discourse of an object language may be conceptualized as the level of how, i.e., discourse that is concerned with "how to “do” a topic: how to recognize it, construct it, maintain it and so on".
Meanwhile, discourse may be conceptualized as the level of why, i.e., it is discourse "concerned with explaining or justifying what a topic means in terms of other topics".
Concepts
A concept in conversation theory, is conceived of as the production, reproduction, and maintenance of a given topic relation from other topic relations , all belonging to a given conversational domain . This implies , where and are used to represent a number on a finite index of numbers. A concept must satisfy the twin condition that it must entail and be entailed by other topics.
A concept in the context of conversation theory is not a class, nor description of a class, nor a stored description: Instead, a concept is specifically used to reconstruct, reproduce or stabilize relations. Thus, if is the head topic of discussion, then implies that the concept of that relation produces, reproduces, and maintains that relation.
Now, a concept itself is considered to consist of the ordered pair containing a program and an interpretation:
Whereby a program attempts to derive a given topic relation, while an interpretation refers to the compilation of that program. In other words, given a specific topic relation, a program attempts to derive that relation through a series of other topic relations, which are compiled in such a way as to derive the initial topic relation. A concept as defined above is considered to be a -procedure, which is embodied by an underlying processor called a -processor.
In this way, Pask envisages concepts as mental organisations that hold a hypothesis and seek to test that hypothesis in order to confirm or deny its validity. This notion of a concept has been noted as formally resembling a TOTE cycle discussed by Miller, Galanter and Pribram. The contents and structure that a concept might have at a given interaction of its continuous deformation can be represented through an entailment structure.
Such conceptual forms are said to be emergent through conversational interactions. They are encapsulated through entailment structures, which is a way by which we may visualize an organized and publicly available collection of resultant knowledge. Entailment structures may afford certain advantages compared to certain semantic network structures, as they force semantic relations to be expressed as belonging to coherent structures. The entailment structure is composed of a series of nodes and arrows representing a series of topic relations and the derivations of such topic relations. For example:
In the above illustration, let , such that there are topic relations that are members of a set of topic relations. Each topic relation is represented by a node, and the entailment represented by the black arc. It follows that in the case above, such that the topics P and Q entail the topic of T.
Assuming we use the same derivation process for all topics in above entailment structure, then we are let with the following product as illustrated above. This represents a minimal entailment mesh consisting of a triad of derivations: , , and . The solid arc indicates that a given head topic relation is derived from subordinate topics, whereas the arcs with dotted lines represent how the head topic may be used to derive other topics. Finally:
Represents two solid arcs permitting alternative derivations of the topic T. This can be expressed as , which reads either the set containing P and Q, or the set containing R and S entail T. Lastly, a formal analogy is shown where two topics T and T''' belonging to two entailment meshes are demonstrated to have a one-to-one correspondence with each other. The diamond shape below denotes analogy relation that can be claimed to exist between any three topics of each entailment mesh.
The relation of one topic T to another T by an analogy can also be seen as: Being based on an isomorphism , a semantic distinction between two individual universes on interpretation . Assuming an analogy holds for two topics in two distinct entailment meshes, then it should hold for all if the analogy is to be considered coherent and stable.
Cognitive Reflector
From conversation theory, Pask developed what he called a "Cognitive Reflector". This is a virtual machine for selecting and executing concepts or topics from an entailment mesh shared by at least a pair of participants. It features an external modelling facility on which agreement between, say, a teacher and pupil may be shown by reproducing public descriptions of behaviour. We see this in essay and report writing or the "practicals" of science teaching.
Lp was Pask's protolanguage which produced operators like Ap which concurrently executes the concept, Con, of a Topic, T, to produce a Description, D. Thus:Ap(Con(T)) => D(T), where => stands for produces'.
A succinct account of these operators is presented in Pask Amongst many insights he points out that three indexes are required for concurrent execution, two for parallel and one to designate a serial process. He subsumes this complexity by designating participants A, B, etc.
In Commentary toward the end of Pask, he states:
The form not the content of the theories (conversation theory and interactions of actors theory) return to and is congruent with the forms of physical theories; such as wave particle duality (the set theoretic unfoldment part of conversation theory is a radiation and its reception is the interpretation by the recipient of the descriptions so exchanged, and vice versa). The particle aspect is the recompilation by the listener of what a speaker is saying. Theories of many universes, one at least for each participant A and one to participant B- are bridged by analogy. As before this is the truth value of any interaction; the metaphor for which is culture itself.
Learning strategies
In order to facilitate learning, Pask argued that subject matter should be represented in the form of structures which show what is to be learned. These structures exist in a variety of different levels depending upon the extent of the relationships displayed. The critical method of learning according to Conversation Theory is "teachback" in which one person teaches another what they have learned.
Pask identified two different types of learning strategies:
Serialists – Progress through a structure in a sequential fashion
Holists – Look for higher order relations
The ideal is the versatile learner who is neither vacuous holist "globe trotter" nor serialist who knows little of the context of his work.
In learning, the stage where one converges or evolves, many Cyberneticians describe the act of understanding as a closed-loop. Instead of simply “taking in” new information, one goes back to look at their understandings and pulls together information that was “triggered” and forms a new connection. This connection becomes tighter and one's understanding of a certain concept is solidified or “stable” (Pangaro, 2003). Furthermore, Gordon Pask emphasized that conflict is the basis for the notion of “calling for'' additional information (Pangaro, 1992).
According to Entwistle, experiments which lead to the investigation of phenomenon later denoted by the term learning strategy came about through the implementation of a variety of learning tasks. Initially, this was done through utilising either CASTE, INTUITION, or the Clobbits pseudo-taxonomy. However, given issues resulting from either the time-consuming nature or operating experiments or inexactness of experimental conditions, new tests were created in the form of the Spy Ring History test and the Smuggler's test. The former test involved a participant having to learn the history of a fictitious spy ring (in other words, the history of a fictitious espionage network); the participant, having to learn about the history of five spies in three countries over the period of five years. The comprehension learning component of the test involved learning the similarities and differences between a set of networks; whereas the operation learning aspect of the test involved learning the role each spy played and what sequence of actions that spy played over a given year.
While Entwistle noted difficulties regarding the length of such tests for groups of students who were engaged in the Spy Ring History test, the results of the test did seem to correspond with the type of learning strategies discussed. However, it has been noted that while Pask and associates work on learning styles has been influential in both the development of conceptual tools and methodology, the Spy Ring History test and Smuggler's test may have been biased towards STEM students than humanities in its implementation, with Entwistle arguing that the "rote learning of formulae and definitions, together with a positive reaction to solving puzzles and problems of a logical nature, are characteristics more commonly found in science than arts student".
Applications
One potential application of conversation theory that has been studied and developed is as an alternative approach to common types of search engine Information retrieval algorithms. Unlike PageRank-like algorithms, which determine the priority of a search result based on how many hyperlinks on the web link to them, conversation theory has been used to apply a discursive approach to web search requests.ThoughtShuffler is an attempt to build a search engine utilizing design principles from conversation theory: In this approach, terms that are input into a search request yield search results relating to other terms that derive or help provide context to the meaning of the first in a way that mimics derivations of topics in an entailment structure. For example, given the input of a search term, a neighbourhood of corresponding terms that comprise the meaning of the first term may be suggested for the user to explore. In doing this, the search engine interface highlights snippets of webpages corresponding to a neighbourhood terms that help provide meaning to the first.
The aim of this design, is to provide just enough information for a user to become curious about a topic in order to induce the intention to explore other subtopics related to the main term input into the search engine.
Gallery
See also
Conversational constraints theory
Integrative learning
Text and conversation theory
Footnotes
References
Citation Sources
Further reading
Ranulph Glanville and Karl H. Muller (eds.), Gordon Pask, Philosopher Mechanic- An Introduction to the Cybernetician's Cybernetician edition echoraum 2007
Aleksej Heinze, Chris Procter, "Use of conversation theory to underpin blended learning", in: International Journal of Teaching and Case Studies (2007) – Vol. 1, No.1/2 pp. 108 – 120
W. R. Klemm, Software Issues for Applying Conversation Theory For Effective Collaboration Via the Internet, Manuscript 2002.
Gordon Pask, Conversation, cognition and learning. New York: Elsevier, 1975.
Gordon Pask, The Cybernetics of Human Learning and Performance, Hutchinson. 1975
Gordon Pask, Conversation Theory, Applications in Education and Epistemology, Elsevier, 1976.
Gordon Pask, Heinz von Foerster's Self-Organisation, the Progenitor of Conversation and Interaction Theories, 1996.
Scott, B. (ed. and commentary) (2011). "Gordon Pask: The Cybernetics of Self-Organisation, Learning and Evolution Papers 1960-1972''" pp 648 Edition Echoraum (2011).
External links
PDFs of Pask's books and key papers at pangaro.com
Conversation Theory – Gordon Pask overview from web.cortland.edu.
Cybernetics And Conversation by Paul Pangaro, 1994–2000.
Conversation Theory: Reasoning about significance and mutuality by Mike Martin and John Dobson,
Conversation Theory developed by the cybernetician Gordon Pask by Yitzhak I. Hayut-Man ea, 1995.
Educational psychology
Oral communication
Science and technology studies | Conversation theory | [
"Technology"
] | 3,895 | [
"Science and technology studies"
] |
13,314,606 | https://en.wikipedia.org/wiki/Untranslated%20region | In molecular genetics, an untranslated region (or UTR) refers to either of two sections, one on each side of a coding sequence on a strand of mRNA. If it is found on the 5' side, it is called the 5' UTR (or leader sequence), or if it is found on the 3' side, it is called the 3' UTR (or trailer sequence). mRNA is RNA that carries information from DNA to the ribosome, the site of protein synthesis (translation) within a cell. The mRNA is initially transcribed from the corresponding DNA sequence and then translated into protein. However, several regions of the mRNA are usually not translated into protein, including the 5' and 3' UTRs.
Although they are called untranslated regions, and do not form the protein-coding region of the gene, uORFs located within the 5' UTR can be translated into peptides.
The 5' UTR is upstream from the coding sequence. Within the 5' UTR is a sequence that is recognized by the ribosome which allows the ribosome to bind and initiate translation. The mechanism of translation initiation differs in prokaryotes and eukaryotes. The 3' UTR is found immediately following the translation stop codon. The 3' UTR plays a critical role in translation termination as well as post-transcriptional modification.
These often long sequences were once thought to be useless or junk mRNA that has simply accumulated over evolutionary time. However, it is now known that the untranslated region of mRNA is involved in many regulatory aspects of gene expression in eukaryotic organisms. The importance of these non-coding regions is supported by evolutionary reasoning, as natural selection would have otherwise eliminated this unusable RNA.
It is important to distinguish the 5' and 3' UTRs from other non-protein-coding RNA. Within the coding sequence of pre-mRNA, there can be found sections of RNA that will not be included in the protein product. These sections of RNA are called introns. The RNA that results from RNA splicing is a sequence of exons. The reason why introns are not considered untranslated regions is that the introns are spliced out in the process of RNA splicing. The introns are not included in the mature mRNA molecule that will undergo translation and are thus considered non-protein-coding RNA.
History
The untranslated regions of mRNA became a subject of study as early as the late 1970s, after the first mRNA molecule was fully sequenced. In 1978, the 5' UTR of the human gamma-globin mRNA was fully sequenced. In 1980, a study was conducted on the 3' UTR of the duplicated human alpha-globin genes.
Evolution
The untranslated region is seen in prokaryotes and eukaryotes, although the length and composition may vary. In prokaryotes, the 5' UTR is typically between 3 and 10 nucleotides long. In eukaryotes, the 5' UTR can be hundreds to thousands of nucleotides long. This is consistent with the higher complexity of the genomes of eukaryotes compared to prokaryotes. The 3' UTR varies in length as well. The poly-A tail is essential for keeping the mRNA from being degraded. Although there is variation in lengths of both the 5' and 3' UTR, it has been seen that the 5' UTR length is more highly conserved in evolution than the 3' UTR length.
Prokaryotes
The 5' UTR of prokaryotes consists of the Shine–Dalgarno sequence (5'-AGGAGGU-3'). This sequence is found 3-10 base pairs upstream from the initiation codon. The initiation codon is the start site of translation into protein.
Eukaryotes
The 5' UTR of eukaryotes is more complex than prokaryotes. It contains a Kozak consensus sequence (ACCAUGG). This sequence contains the initiation codon. The initiation codon is the start site of translation into protein.
Links to disease
The importance of these untranslated regions of mRNA is just beginning to be understood. Various medical studies are being conducted that have found connections between mutations in untranslated regions and increased risk for developing a particular disease, such as cancer. For example, associations between polymorphisms in the HLA-G 3′UTR region and development of colorectal cancer have been discovered. Single Nucleotide Polymorphisms in the 3' UTR of another gene have also been associated with susceptibility to preterm birth. Mutations in the 3' UTR of the APP gene are related to development of cerebral amyloid angiopathy.
Further study
Through the recent study of untranslated regions, general information has been gathered about the nature and function of these elements. However, there is still much that is unknown about these regions of mRNA. Since the regulation of gene expression is critical in the proper function of cells, this is an area of study that needs to be investigated further. It is important to consider that mutations in 3' untranslated regions have the potential to alter the expression of several genes that may appear unrelated. We are only beginning to understand the links between proper untranslated region function, and disease states of cells.
See also
Atlas of UTR Regulatory Activity
Coding region
Five prime untranslated region
History of RNA biology
MiRNA
Three prime untranslated region
Upstream open reading frames (uORFs)
References
External links
UTResource
RNA
Gene expression | Untranslated region | [
"Chemistry",
"Biology"
] | 1,170 | [
"Gene expression",
"Molecular genetics",
"Cellular processes",
"Molecular biology",
"Biochemistry"
] |
13,314,634 | https://en.wikipedia.org/wiki/Fern%20flower | The fern flower is a magic flower in Baltic mythology (, ), in Estonian mythology () and in Slavic mythology (, , , ).
Tradition
According to the myth, this flower blooms for a very short time on the eve of the summer solstice (celebrated on June 21, June 23 and 24 or sometimes July 7). It brings fortune to the person who finds it. In some tales, it allows humans to understand animal speech. It is closely guarded by evil spirits and though the one who succeeds in gathering it can receive earthly riches, that attainment has always brought ill luck, so some leave it alone.
Estonian and Baltic
In the Estonian, Lithuanian and Latvian tradition, the fern flower is supposed to appear only on the night of 23 to 24 June during the celebration of the summer solstice which is called Jāņi in Latvia, Joninės or Rasos in Lithuania, Jaaniõhtu or Jaaniöö in Estonia and juhannus in Finland. The celebration has pre-Christian origins. In addition to the idea that the finder of the fern flower will become rich or happy, here, the fern flower is sometimes perceived a symbol of fertility. During this supposedly magical night, young couples go into the woods "seeking the fern flower", which is most commonly read as a euphemism for sex. Sex can lead to pregnancy; the child could be thought of as the fern flower.
Referring to this tradition, Papardes zieds ("fern flower" in Latvian) is the name of an NGO in Latvia that promotes education about matters pertaining to sexuality, fertility, and relationships.
Swedish
Similar beliefs are attested in Sweden, where the fern flower was said to be found only at midnight on Midsummer's Eve, and even then was protected by magic and thus hard to obtain. This also applied to horsetail and daphne flowers; of daphne, a flowering plant, it was said: "The flowers are a rarity if picked on nights when they are believed to bloom. The naturally occurring flowers no one believes to be daphne flowers."
East Slavic
In Russia, Ukraine, Belarus, and in Poland the holiday is practiced on the eve of Ivan Kupala Day. Young girls wear wreaths in their hair and couples go into the woods searching for the fern flower. When they come out of the woods, if the male is wearing the girl's wreath, it means the couple is engaged to be married.
According to folklore, the flower is Chervona Ruta. The flower is yellow, but according to legend, it turns red on the eve of Ivan Kupala Day.
Polish
In many parts of Poland adder’s tongue Ophioglossum vulgatum was believed to be fern flower. It is a fern that does not look like a fern. It lacks the characteristic divided fine leaves. The leaf is simple and is accompanied by a stalk with spores. Altogether it looks like a green calla-type flower or a plantain. Hundreds of years ago, people in the Polish countryside figured out that it was a kind of fern. Central Europe is rife with stories of a flowering fern blooming only on Midsummer night or at Christmas. And in Poland, the flowering fern usually meant adder’s tongue. A lot of magic powers were attributed to this plant. The plant is very small and easy to overlook in grass swards. It was believed that adder’s tongue opened all locks. It also brought immense luck in love. The following love charm was uttered while collecting the plant:
Nasięźrzale, nasięźrzale,
Rwę cię śmiale,
Pięcią palcy, szóstą, dłonią,
Niech się chłopcy za mną gonią;
Po stodole, po oborze,
Dopomagaj, Panie Boże.
Adder’s tongue, adder’s tongue,
I bravely collect you,
With five fingers, with the sixth hand;
Let boys chase me,
Around the barn, around the shed,
Let God help.
Blooming ferns
Ferns are not flowering plants, but the myth may be rooted in a reality when the grouping of plants was not exactly the same as the modern taxonomy. Numerous flowering plants resemble ferns, or have fern-like foliage, and some open flowers during nighttime. Some true ferns, like Osmunda regalis, have sporangia in tight clusters (termed "fertile fronds") which may appear in flower-like clusters and so be commonly known as "flowering ferns".
See also
Blue flower
St. John's Eve
Notes
References
Mythological plants
Slavic mythology
Baltic mythology
Flowers in religion
Summer solstice | Fern flower | [
"Astronomy"
] | 952 | [
"Time in astronomy",
"Summer solstice"
] |
13,314,856 | https://en.wikipedia.org/wiki/Unified%20Code%20for%20Units%20of%20Measure | The Unified Code for Units of Measure (UCUM) is a system of codes for unambiguously representing measurement units. Its primary purpose is machine-to-machine communication rather than communication between humans. UCUM is used by different organizations like IEEE, and standards like DICOM, LOINC, HL7, and ISO 11240:2012.
The code set includes all units defined in ISO 1000, ISO 2955-1983, ANSI X3.50-1986, HL7 and ENV 12435, and explicitly and verifiably addresses the naming conflicts and ambiguities in those standards to resolve them. It provides for representations of units in 7 bit ASCII for machine-to-machine communication, with unambiguous mapping between case-sensitive and case-insensitive representations.
A reference open-source implementation is available as a Java applet. There is also an OSGi-based implementation at Eclipse Foundation.
Base units
Units are represented in UCUM with reference to a set of seven base units. The UCUM base units are the metre for measurement of length, the second for time, the gram for mass, the coulomb for charge, the kelvin for temperature, the candela for luminous intensity, and the radian for plane angle. The UCUM base units form a set of mutually independent dimensions as required by dimensional analysis.
Some of the UCUM base units are different from the SI base units. UCUM is compatible with, but not isomorphic with, SI. There are four differences between the two sets of base units:
The gram is the base unit of mass instead of the kilogram, since in UCUM base units do not have prefixes.
Electric charge is the base quantity for electromagnetic phenomena instead of electric current, since the elementary charge of electrons is more fundamental physically.
The mole is dimensionless in UCUM, since it can be defined in terms of the Avogadro number,
The radian is a distinct base unit for plane angle, to distinguish angular velocity from rotational frequency and to distinguish the radian from the steradian for solid angles.
Metric and non-metric units
Each unit represented in UCUM is identified as either "metric" or "non-metric". Metric units can accept metric prefixes as in SI. Non-metric units are not permitted to be used with prefixes. All of the base units are metric.
UCUM refers to units that are defined on non-ratio scales as "special units". Common examples include the bel and degree Celsius. While these are not considered metric units by UCUM, UCUM nevertheless allows metric prefixes to be used with them where this is common practice.
Binary prefixes are also supported.
Arbitrary units
UCUM recognizes units that are defined by a particular measurement procedure, and which cannot be related to the base units. These units are identified as "arbitrary units". Arbitrary units are not commensurable with any other unit; measurements in arbitrary units cannot be compared with or converted into measurements in any other units. Many of the recognized arbitrary units are used in biochemistry and medicine.
Derived units
Any metric unit in any common system of units can be expressed in terms of the UCUM base units.
See also
Outline of metrology and measurement
GNU Units
International vocabulary of metrology
Notes
References
Further reading
External links
unitsofmeasure.org - The official UCUM web site. The UCUM Organization
Unified Code for Units of Measure (UCUM) at Lister Hill National Center for Biomedical Communications (LHNCBC), U.S. National Library of Medicine (NLM)
dimensioned::unit_systems::ucum - Rust
The UCUM-LHC Validator and Converter
UCUM Web Service (API)
"UOMo", Eclipse Foundation (2010)
"UCUM", Regenstrief Institute (2008)
Encodings
Metrology
Systems of units
International standards | Unified Code for Units of Measure | [
"Mathematics"
] | 799 | [
"Quantity",
"Systems of units",
"Units of measurement"
] |
13,315,204 | https://en.wikipedia.org/wiki/Duckbill%20valve | A duckbill valve is a check valve, usually manufactured from rubber or synthetic elastomer, and has two or more flaps, usually shaped like the beak of a duck. It is commonly used in medical applications to prevent contamination due to backflow.
One end of the valve is stretched over the outlet of a supply line, conforming itself to the shape of the line, usually round. The other end, the duckbill, retains its natural flattened shape. When a fluid is pumped through the supply line and therefore the duckbill, the flattened end opens to permit the pressurized fluid to pass. When pressure is removed, however, the duckbill end returns to its flattened shape, preventing backflow.
The duckbill valve is similar in function to the mitral valve in the heart. See also Heimlich valve.
A trifold form of this valve, known as a joker valve, is used in one popular marine toilet.
Also known as a spear valve or flutter valve, this automatic device serves as a gas exhaust valve on the inside of some twin-hose diving regulators and as an excess gas release valve on the outside of certain mid-twentieth-century dry diving suits.
References
Valves | Duckbill valve | [
"Physics",
"Chemistry"
] | 242 | [
"Physical systems",
"Valves",
"Hydraulics",
"Piping"
] |
13,315,514 | https://en.wikipedia.org/wiki/Design%20technology | Design technology, or D.T., (also Digital Delivery (DD)) is the study, design, development, application, implementation, support and management of computer and non-computer based technologies for the express purpose of communicating product design intent and constructability. Design technology can be applied to the problems encountered in construction, operation and maintenance of a product.
At times there is cross-over between D.T. and Information Technology, whereas I.T. is primarily focused on overall network infrastructure, hardware and software requirements, and implementation, D.T. is specifically focused on supporting, maintaining and training design and engineering applications and tools and working closely with I.T. to provide necessary infrastructure, for the most effective use of these applications and tools.
Within the building design, construction and maintenance industry (also known as AEC/O/FM), the product is the building and the role of D.T., is the effective application of technologies within all phases and aspects of building process. D.T. processes have adopted Building Information Modeling (BIM) to quicken construction, design and facilities management using technology. So though D.T. encompasses BIM and Integrated Project Delivery, I.P.D., it is more overarching in its directive and scope and likewise looks for ways to leverage and more effectively utilize C.A.D., Virtual Design & Construction, V.D.C., as well as historical and legacy data and systems.
D.T. is applicable to industrial design and product design and the manufacturing and fabrication processes therein.
There are formal courses of study in some countries known as design and technology that focus on particular areas. In this case, the above definition remains valid, if for instance one takes the subject textiles technology and replace the product in the above definition with textile.
See also
Automation
Process simulation/Design
System/Process Engineering/Design
Computer-aided design (CAD)
Building Information Modeling (BIM)
Integrated Project Delivery (IPD)
Virtual Design and Construction (VDC)
Information Technology (IT)
References
Design
Technology by type | Design technology | [
"Engineering"
] | 425 | [
"Design"
] |
13,315,805 | https://en.wikipedia.org/wiki/Skyhook%20Wireless | Skyhook was a location technology company based in Boston, Massachusetts, specializing in location positioning. Founded in 2003, Skyhook initially focused on geolocating Wi-Fi access points by wardriving for commercial purposes. Skyhook transitioned to developing hybrid positioning.
History
Skyhook was founded in 2003 by Ted Morgan and Michael Shean. Skyhook's database was initially gathered through wardriving, when the company sent teams of drivers around the United States, Canada, Western Europe, and selected Asian countries to map out Wi-Fi hotspots.
In April 2010, Apple decided to switch iPhones running on iPhone OS 3.2 and newer to their own location database after previously using a combination of Skyhook's and Google's.
In September 2010, Skyhook sued Google over the use of Wi-Fi locator technology in cell phones. The complaint claimed that Andy Rubin, Google's Vice President for Engineering, gave Sanjay K. Jha, Chief Executive of Motorola's mobile devices' division, a "stop ship" order, preventing Motorola from shipping phones with the Android operating system using the Skyhook software. The litigation was settled in 2015, with Skyhook receiving $90 million in a settlement with the tech giant, a third of which was spent on legal fees. The figure was shown in a securities filing by Liberty Broadband Corporation, Skyhook's Colorado-based parent company.
In February 2014, Skyhook Wireless was acquired by True Position Inc., a subsidiary of Liberty Broadband. In 2016, the two companies merged under the Skyhook brand, now under Liberty Broadband, which is a part of the Liberty Media family. Skyhook also introduced a range of products: Retailer Personas, Power Personas, and On-Demand Personas.
In February 2019, Skyhook announced that it was working closely with Qualcomm Technologies to bring Wi-Fi positioning and location-assistance services based on Qualcomm Snapdragon Wear platforms. In September 2019, Mozilla announced changes to commercial use of its Mozilla Location Service, which resulted in SailfishOS location services not being able to use the service anymore. The changes were made due to patent infringement allegations by Skyhook. In February 2020, Deutsche Telekom announced that Skyhook became one of its technology partners. In April 2020, Skyhook partnered with Kyocera to provide location services to DuraXV Extreme, a rugged flip phone. Skyhook and Combain announced a collaboration in a common press release issued in April 2020.
In 2022, Qualcomm acquired Skyhook.
Services
Skyhook offers a software development kit, which allows developers to create location-enabled applications using Skyhook's software. The SDK supports Android 2.2 (Froyo), 2.3.x (Gingerbread), 4.0.x (Ice Cream Sandwich), 4.1.x (Jelly Bean), 4.4 (KitKat), 5.0-5.1 (Lollipop), and 6.0 (Marshmallow), including forked platforms such as the Kindle Fire, along with Linux, Windows, and Mac OS X.
See also
Hybrid positioning system
Mobile phone tracking
Local Positioning Systems
Wi-Fi positioning system
References
Geomarketing
Wi-Fi
Companies based in Boston
Software companies based in Massachusetts
Location-based software
Software companies of the United States
American companies established in 2003
2003 establishments in Massachusetts
Software companies established in 2003 | Skyhook Wireless | [
"Technology"
] | 725 | [
"Wireless networking",
"Wi-Fi"
] |
13,315,993 | https://en.wikipedia.org/wiki/KIOSK | KIOSK is an art, design and architecture magazine, the first edition of which was published in November 2007. The magazine was created by artists, designers, architects, historians, theorists, curators and experts in the built environment and has a wrap-around poster cover of the work of a featured artist, designer, or architect. It is published on a biannual basis.
KIOSK is edited by Marq Smith, and published by Simon Ofield.
Notable contributors
Issue 1 (Winter 2007/08) contains:
Fiona Banner (Feature poster artist)
Jack Lohman, Director of the Museum of London
Marilyn Martin, Director of Art Collections, Iziko South African Museum
Geoff Grandfield
Sara Fanelli
References
External links
KIOSK website
Architecture magazines
Biannual magazines published in the United Kingdom
Visual arts magazines published in the United Kingdom
Design magazines
Magazines established in 2007 | KIOSK | [
"Engineering"
] | 177 | [
"Design magazines",
"Design"
] |
13,316,007 | https://en.wikipedia.org/wiki/Million%20Dollar%20Strong | Million Dollar Strong is a parody hip-hop music duo portrayed by Mike O'Connell and Ken Jeong, notable for the 2007 viral video "What's It Gonna Be?", which became popular on YouTube. MTV announced a film based on the aspiring band.
See also
Comedy hip hop
References
External links
"What's It Gonna Be?" via Funny or Die
Viral videos | Million Dollar Strong | [
"Technology"
] | 79 | [
"Computing stubs",
"World Wide Web stubs"
] |
13,317,017 | https://en.wikipedia.org/wiki/MSCDEX | MSCDEX or Microsoft CD-ROM Extensions is a software program produced by Microsoft and included with MS-DOS 6.x and certain versions of Windows to provide CD-ROM support. Earlier versions of MSCDEX since 1986 were installable add-ons for MS-DOS 3.1 and higher.
Overview
The program is a driver executable which allows DOS programs to recognize, read, and control CD-ROMs using the High Sierra and – since version 2.0 as of 1988 – also the ISO 9660 file systems. This requires the previous loading of an appropriate CD-ROM device driver (example: OAKCDROM.SYS), usually from CONFIG.SYS.
The final version of the MSCDEX program was 2.25, included with Windows 95 and used when creating bootable floppy disks with CD-ROM support. Starting with Windows 95, CD-ROM access became possible through a 32-bit CDFS driver.
The driver uses the Microsoft networks interface in MS-DOS. This is the reason that at least version 3.1 of MS-DOS is required. The driver essentially looks similar to a network drive from the system perspective. It is implemented as a terminate-and-stay-resident program and an extension to the redirector interface (CDEX).
Datalight ROM-DOS includes an implementation of MSCDEX.
Alternatives
Novell DOS 7, Caldera OpenDOS 7.01 and DR-DOS 7.02 and higher provide a functional equivalent to MSCDEX named NWCDEX, which also runs under MS-DOS and PC DOS. It has more flexible load-high capabilities, also allowing to relocate and run in protected mode through DPMS on 286 and higher processors, thereby leaving only a 7 KB stub in conventional or upper memory (in comparison to MSCDEX, which occupies some 16 KB). Using EMS with a page frame, NWCDEX can reduce its footprint even down to a few bytes in conventional memory. In contrast to MSCDEX, the driver does not depend on undocumented DOS APIs and therefore, with a third-party helper tool named INSTCDEX, can be loaded via statements and be fully functional in CONFIG.SYS thereby increasing chances to load the driver high and, under these operating systems, allow to load other drivers not only from hard disk but also from CD-ROM while the operating system is still processing CONFIG.SYS. An alternative solution, but less flexible, some versions of DR-DOS offer to delay the installation of a driver in CONFIG.SYS until after the DOS data segment relocation via INSTALLLAST.
Based on NWCDEX, IMS REAL/32, a successor to Novell's Multiuser DOS and Digital Research's Concurrent DOS, provides a similar driver named IMSCDEX.
A cloaked variant of MSCDEX was provided as part of Helix Software's Multimedia Cloaking product. It uses Cloaking to relocate and run in protected mode on 386 and higher processors.
Corel offered CORELCDX.COM as alternative to MSCDEX.
There's a free alternative called SHSUCDX that is used with the IDE/ATA driver UIDE.SYS first released in 2005. It is often used with FreeDOS and works with other DOSes as well.
In 1998, Caldera provided a DRFAT32 driver for DR-DOS to dynamically mount and unmount FAT32 volumes on DOS versions otherwise not natively supporting FAT32. DRFAT32 uses a variation and extension of the CDEX API in order to achieve this and work with older DOS versions.
See also
List of DOS commands
References
Further reading
(Self-extracting archive, includes Microsoft MS-DOS CD-ROM Extensions Hardware-Dependent Device Driver Specification)
External links
MS-DOS and Windows command line MSCDEX command
External DOS commands
Windows commands | MSCDEX | [
"Technology"
] | 797 | [
"Windows commands",
"Computing commands"
] |
13,317,605 | https://en.wikipedia.org/wiki/Many-to-many%20%28data%20model%29 | In systems analysis, a many-to-many relationship is a type of cardinality that refers to the relationship between two entities, say, A and B, where A may contain a parent instance for which there are many children in B and vice versa.
Data relationships
For example, think of A as Authors, and B as Books. An Author can write several Books, and a Book can be written by several Authors. In a relational database management system, such relationships are usually implemented by means of an associative table (also known as join table, junction table or cross-reference table), say, AB with two one-to-many relationships and . In this case the logical primary key for AB is formed from the two foreign keys (i.e. copies of the primary keys of A and B).
In web application frameworks such as CakePHP and Ruby on Rails, a many-to-many relationship between entity types represented by logical model database tables is sometimes referred to as a HasAndBelongsToMany (HABTM) relationship.
See also
Associative entity
One-to-one (data model)
One-to-many (data model)
References
Data modeling | Many-to-many (data model) | [
"Engineering"
] | 247 | [
"Data modeling",
"Data engineering"
] |
13,318,208 | https://en.wikipedia.org/wiki/Peter%20Adolf%20Thiessen | Peter Adolf Thiessen (6 April 1899 – 5 March 1990) was a German physical chemist and a tribologist– he is credited as the founder of the tribochemistry.
At the close of the World War II, he voluntarily went to the Soviet Union and played a crucial role in advancing the Soviet program of nuclear weapons, and was a recipient of national honors of the Soviet Union. Upon his return to East Germany in 1956, Thiessen engaged his life in the advancement of applied applications of the physical chemistry.
Education
Thiessen was born in Schweidnitz, Silesia, Prussia, which now is known as Świdnica, Lower Silesian in Poland, on 6 April 1899. Thiessen hailed from a wealthy German family, which owned a land in Schweidnitz.
From 1919 to 1923, he attended and studied chemistry at the Breslau University, University of Freiburg, University of Greifswald, and the University of Göttingen. He received his doctorate in chemistry in 1923 under Richard Adolf Zsigmondy at Göttingen.
Career
Early years
In 1923, Thiessen was a supernumerary assistant professor of chemistry at the University of Göttingen and from 1924 to 1930 was a regular professor. He joined the Nazi Party in 1925; and became a Privatdozent at Göttingen in 1926. In 1930, he became head of the department of inorganic chemistry there, and in 1932 he also became an untenured extraordinarius professor.
In 1933, Thiessen became a department chair of chemistry at the Kaiser-Wilhelm Institute for Physical Chemistry and Electrical Chemistry (KWIPC) of the Kaiser-Wilhelm Gesellschaft (KWG). For a short time in 1935, he became an ordinarius professor of chemistry at the University of Münster. Later, that year and until 1945, he became an ordinarius professor at the Humboldt University of Berlin and director of the KWIPC in Berlin-Dahlem. As director of the KWIPC, he transformed it into a scientific model based on the Nazi Party's guidelines.
Thiessen was the main advisor and confidant to Rudolf Mentzel, who was head of the chemistry and organic materials section of the Reichsforschungsrat (RFR, Reich Research Council). Thiessen, as director of the KWIPC, had a flat on Faradayweg in Dahlem that the former director Fritz Haber used for business purposes; Thiessen shared this flat with Mentzel.
In the Soviet Union
Before the end of World War II, Thiessen had Communist contacts. He, Manfred von Ardenne, director of his private laboratory (Research Laboratory for Electron Physics), Gustav Hertz, Nobel Laureate and director of the second research laboratory at Siemens, and Max Volmer, ordinarius professor and director of the Physical Chemistry Institute at the Technical University of Berlin, had made a pact. The pact was a pledge that whoever first made contact with the Soviet authorities would speak for the rest. The objectives of their pact were threefold: (1) prevent plunder of their institutes, (2) continue their work with minimal interruption, and (3) protect themselves from prosecution for any political acts of the past. On 27 April 1945, Thiessen arrived at von Ardenne’s institute in an armored vehicle with a major of the Soviet Army, who was also a leading Soviet chemist. All four were taken into the Soviet custody and were held in Russia where Von Ardenne was made head of Institute A, in Sinop, a suburb of Sukhumi. Hertz was made head of Institute G, in Agudseri (Agudzery), about 10 km southeast of Sukhumi and a suburb of Gul’rips (Gulrip’shi). Volmer went to the Nauchno-Issledovatel’skij Institut-9 (NII-9, Scientific Research Institute No. 9), in Moscow; he was given a design bureau to work on the production of heavy water. In Institute A, Thiessen became leader for developing engineering design techniques for manufacturing porous barriers for isotope separation using the gaseous and centrifugal technologies.
In 1949, six German scientists, including Hertz, Thiessen, and Barwich, were called in for consultation at Sverdlovsk-44, which was responsible for uranium enrichment using the gaseous diffusion. The plant, which was smaller than the American Oak Ridge Laboratory's K-25 gaseous diffusion plant, was getting only a little over half of the expected 90pc or higher enrichment. Awards for uranium enrichment technologies were made in 1951 after testing of a bomb with uranium; the first test was with plutonium. Thiessen received a Stalin Prize, first class in 1953.
He is credited with founding the field of tribochemistry, which he formulated when encountering problems to make the gaseous diffusion method feasible for the Soviet nuclear weapons.
Return to East Germany
In 1953, Thiessen was notified by the Soviet administration in Russia that he would allowed to return to Germany but had to quarantined for at least two years, which was a standard practice for the German experts in Soviet program of nuclear weapons. He performed unclassified research in the Soviet Union and returned to East Germany in 1955 where he was elected as a Fellow of the German Academy of Sciences in East Berlin, and from 1956 was director of the Institute of Physical Chemistry in East Berlin. From 1957 to 1965, he was also chairman of the Research Council of the German Democratic Republic..
From 1965 till 1990, Thiessen served on different research capacities to advance the field of Tribology, for which he is credited as one of the founders, and died in East Berlin on 5 March 1990, aged 90.
Books
Peter Adolf Thiessen and Helmut Sandig Planung der Forschung (Dietz, 1961)
Peter Adolf Thiessen Erfahrungen, Erkenntnisse, Folgerungen (Akademie-Verlag, 1979)
Peter Adolf Thiessen Forschung und Praxis formen die neue Technik (Urania-Verl., 1961)
Peter Adolf Thiessen Vorträge zum Festkolloquium anlässlich des 65. Geburtstages von P. A. Thiessen (Akademie-Verl., 1966)
Peter Adolf Thiessen, Klaus Meyer, and Gerhard Heinicke Grundlagen der Tribochemie (Akademi-Verlar, 1967)
Articles
Peter Adolf Thiessen Die physikalische Chemie im nationalsozialistischen Staat, Der Deutscher Chemiker. Mitteilungen aus Stand / Beruf und Wissenschaft (Supplement to Angewandte Chemie. Zeitschrift des Vereins Deutsche Chemiker, No.19.) Volume 2, No. 5, May 9, 1936. Reprinted in English in Hentschel, Klaus (editor) and Ann M. Hentschel (editorial assistant and translator) Physics and National Socialism: An Anthology of Primary Sources (Birkhäuser, 1996) 134-137 as Document 48. Thiessen: Physical Chemistry in the National Socialist State [May 9, 1936].
Notes
References
Albrecht, Ulrich, Andreas Heinemann-Grüder, and Arend Wellmann Die Spezialisten: Deutsche Naturwissenschaftler und Techniker in der Sowjetunion nach 1945 (Dietz, 1992, 2001)
Barwich, Heinz and Elfi Barwich Das rote Atom (Fischer-TB.-Vlg., 1984)
Beneke, Klaus Die Kolloidwissenschaftler Peter Adolf Thiessen, Gerhart Jander, Robert Havemann, Hans Witzmann und ihre Zeit (Knof, 2000)
Heinemann-Grüder, Andreas Die sowjetische Atombombe (Westfaelisches Dampfboot, 1992)
Heinemann-Grüder, Andreas Keinerlei Untergang: German Armaments Engineers during the Second World War and in the Service of the Victorious Powers in Monika Renneberg and Mark Walker (editors) Science, Technology and National Socialism 30-50 (Cambridge, 2002 paperback edition)
Hentschel, Klaus (editor) and Ann M. Hentschel (editorial assistant and translator) Physics and National Socialism: An Anthology of Primary Sources (Birkhäuser, 1996)
Klaus Hentschel The Mental Aftermath: The Mentality of German Physicists 1945 – 1949 (Oxford, 2007)
Holloway, David Stalin and the Bomb: The Soviet Union and Atomic Energy 1939–1956 (Yale, 1994)
Kruglov, Arkadii The History of the Soviet Atomic Industry (Taylor and Francis, 2002)
Naimark, Norman M. The Russians in Germany: A History of the Soviet Zone of Occupation, 1945-1949 (Hardcover - Aug 11, 1995) Belknap
Oleynikov, Pavel V. German Scientists in the Soviet Atomic Project, The Nonproliferation Review Volume 7, Number 2, 1 – 30 (2000). The author has been a group leader at the Institute of Technical Physics of the Russian Federal Nuclear Center in Snezhinsk (Chelyabinsk-70).
External links
Fritz Haber Institute - MPG
1899 births
1990 deaths
People from Świdnica
German barons
University of Breslau alumni
University of Freiburg alumni
University of Greifswald alumni
University of Göttingen alumni
German chemists
German physical chemists
20th-century German chemists
Scientists from the Province of Silesia
Academic staff of the University of Göttingen
Academic staff of the University of Münster
Academic staff of the Humboldt University of Berlin
Nazi Party members
German expatriates in the Soviet Union
Nuclear weapons program of the Soviet Union people
Recipients of the Stalin Prize
East German scientists
Recipients of the National Prize of East Germany
Members of the German Academy of Sciences at Berlin
Max Planck Institute directors
Tribologists
Foreign members of the USSR Academy of Sciences | Peter Adolf Thiessen | [
"Materials_science"
] | 2,062 | [
"Tribology",
"Tribologists"
] |
13,318,264 | https://en.wikipedia.org/wiki/Index%20of%20civil%20engineering%20articles | This is an alphabetical list of articles pertaining specifically to civil engineering. For a broad overview of engineering, please see List of engineering topics. For biographies please see List of civil engineers.
A
Accuracy and precision –
American Society of Civil Engineers –
Applied mechanics –
Arch
B
Beam (structure) –
Bending –
Brittle –
Buckling
C
Carbon fiber –
Check dam –
Classical mechanics –
Composite material –
Compressive strength –
Computational fluid dynamics –
Computer-aided design –
Conservation of mass –
Concrete –
Corrosion
D
Dam –
Damping ratio –
Deformation –
Delamination –
Design –
Dimensionless number –
Drafting –
Dynamics
E
Elasticity –
Engineering drawing –
Exploratory engineering
F
Factor of safety –
Fatigue –
Fillet –
Finite element analysis –
Finite element method –
Fluid mechanics –
Force –
Friction –
Fundamentals of Engineering exam
G
Gauge –
Gauge (engineering) –
Granular material
H
Heating and cooling systems –
Hydraulics –
Hydrostatics
I
Inclined plane –
Inertia –
Instrumentation –
Invention
J
Joint
L
Lever –
Liability –
Life cycle cost analysis –
Limit state design –
Load transfer
M
Margin of safety –
Mass transfer –
Materials –
Materials engineering –
Material selection –
Mechanics –
Moment –
Moment of inertia
N
Normal stress –
Nozzle
P
Physics –
Plasticity –
Plastic moment –
Poisson's ratio –
Position vector –
Pressure –
Product lifecycle management –
Professional engineer –
Project management –
Pulley –
Pump –
Pile foundation
Q
Quality –
Quality control –
Quantity surveying
R
Reliability engineering –
Resistive force –
Reverse engineering –
Rigid body –
Reinforced concrete –
S
Safety engineering –
Shear force diagrams –
Shear modulus –
Shear strength –
Shear stress –
Simple machine –
Simulation –
Slide rule –
Solid mechanics –
Solid modeling –
Spoolbase –
Statics –
Stress–strain curve –
Structural failure –
Student design competition –
Surveying –
T
Technical drawing –
Technology –
Tensile strength –
Tensile stress –
Theodolite –
Theory of elasticity –
Toughness –
Turbine –
V
Vector –
Viscosity –
Vibration
W
Wedge –
Weight transfer –
Weir
Y
Yield strength –
Young's modulus
Civil engineering
Civil engineering topics | Index of civil engineering articles | [
"Engineering"
] | 419 | [
"Construction",
"Civil engineering"
] |
13,318,456 | https://en.wikipedia.org/wiki/Ocinaplon | Ocinaplon is an anxiolytic drug in the pyrazolopyrimidine family of drugs. Other pyrazolopyrimidine drugs include zaleplon and indiplon.
Ocinaplon has a similar pharmacological profile to the benzodiazepine family of drugs, but with mainly anxiolytic properties and relatively little sedative or amnestic effect.
Medical uses
A 2019 review found tentative evidence of benefit in anxiety.
Mechanism of action
The mechanism of action by which ocinaplon produces its anxiolytic effects is by modulating GABAA receptors, although ocinaplon is more subtype-selective than most benzodiazepines.
Availability
Development of ocinaplon is discontinued due to liver complications that occurred in one of the Phase III subjects.
Synthesis
Condensation of 4-Acetylpyridine with N,N-Dimethylformamide dimethyl acetal (DMFDMA) gives the "enamide" (3). This is then condensed with (3-Amino-1H-pyrazol-4-yl)(2-pyridinyl)methanone (4) (96219-90-8). This is the same intermediate as was used in the synthesis of zaleplon in which the nitrile is replaced by a 2-acetylpyridil moiety. This affords the anxiolytic agent ocinaplon (5).
References
Hepatotoxins
Pyrazolopyrimidines
Sedatives
Pyridines
Ketones
GABAA receptor positive allosteric modulators | Ocinaplon | [
"Chemistry"
] | 360 | [
"Ketones",
"Functional groups"
] |
13,318,891 | https://en.wikipedia.org/wiki/Nalfurafine | Nalfurafine (INN, USAN) (brand name Remitch; former developmental code names TRK-820, AC-820, MT-9938) is an antipruritic (anti-itch drug) that is marketed in Japan for the treatment of uremic pruritus in individuals with chronic kidney disease undergoing hemodialysis. It activates the κ-opioid receptor (KOR) and is potent, selective, and centrally active. It was the first selective KOR agonist approved for clinical use. It has also been dubiously referred to as the "first non-narcotic opioid drug" in history.
History
Nalfurafine was derived from structural modification of the opioid antagonist naltrexone. It was first synthesized and characterized in 1998, and was approved for clinical use in Japan as an intravenous drug under the brand name Remitch in 2009. The developer of nalfurafine also sought approval in Europe under the brand name Winfuran, but the Marketing Authorization Application was declined by the European Medicines Agency. The drug was originally developed as an analgesic in surgery, but while effective in animal models of nociception, it was repurposed as an antipruritic at lower treatment doses due to an apparently unacceptable incidence of sedative effects in humans. As of 2015, nalfurafine is also in clinical trials for the treatment of cholestatic pruritus in Japan for patients with chronic liver disease, and for the treatment of uremic pruritus in the United States.
Effects
Unlike other KOR agonists, nalfurafine does not produce hallucinogenic effects in humans. Single intramuscular injections of up to 30 μg are well tolerated by humans, whereas a dose of 40 μg produced "moderate behavioral/psychological side effects" (possibly referring to sedation), though apparently did not produce any psychotomimetic or dysphoric effects. In rodents, a low dose of nalfurafine (10–40 μg/kg) was found not to produce conditioned place preference or aversion, though a high dose (80 μg/kg) did induce significant place aversion. The most common side effect of low-dose nalfurafine seen in clinical trials was insomnia (observed in 10–15% of patients), with few other adverse effects observed. In addition, tolerance to the antipruritic effects of nalfurafine was not found after treatment of patients with the drug for one year, and nalfurafine has shown no evidence of either physical nor psychological dependence in humans. The drug also shows lower evidence of tolerance for effects such as analgesia and sedation in animals relative to other KOR agonists. In animals, nalfurafine produces anti-scratch, antinociceptive, sedative, and diuretic effects.
Mechanism of action
Nalfurafine is an orally active, centrally acting, highly potent, selective full agonist of the κ-opioid receptor (KOR) (Ki = 75 pM; EC50 = 25 pM). As touched on above, nalfurafine shows atypical properties as a KOR agonist relative to other drugs. Notably, it does not completely substitute for the prototypical KOR agonist U-50488 in rodents, indicating qualitative differences in the discriminative effects of the two compounds. Moreover, unlike U-50488, it produces neither conditioned place aversion or preference in rodents. The drug is a 4,5-epoxymorphinan derivative, and is structurally unique relative to other KOR agonists. Nalfurafine may be a biased agonist of the KOR or a KOR subtype-selective agonist. Indeed, it has been found to act as a biased agonist of the KOR, preferring activation of β-arrestin signaling in vitro, but paradoxically, β-arrestin appears to be responsible for KOR agonist-induced aversion, and nalfurafine furthermore shows paradoxical effects in vivo that are not consistent with its in vitro profile. As such, more research is needed to clarify the distinct mechanisms and effects of this drug.
Nalfurafine has been found in vitro to bind to the μ-opioid receptor and to possess weak partial agonist activity at this site, albeit with much lower affinity relative to the KOR. However, in vivo, nalfurafine has shown no indications of MOR agonism or antagonism in animals or humans, including no evidence of rewarding or reinforcing effects or physical dependence.
Research
Nalfurafine has been found to be effective in a variety of animal models relevant to drug abuse, addiction, and dependence, and may represent a novel potential treatment for these maladies. In rodents, the drug attenuates the discriminative and rewarding effects of cocaine and the rewarding and locomotor effects of morphine, and diminishes the mecamylamine-precipitated aversive effect of nicotine withdrawal.
See also
Asimadoline
Butorphanol
Difelikefalin
Nalbuphine
Nalmefene
Naltriben
Noribogaine
RB-64
Salvinorin A
References
Tertiary alcohols
Alkene derivatives
Carboxamides
Antipruritics
Biased ligands
4,5-Epoxymorphinans
3-Furyl compounds
Kappa-opioid receptor agonists
Hydroxyarenes
Semisynthetic opioids
Cyclopropyl compounds | Nalfurafine | [
"Chemistry"
] | 1,169 | [
"Biased ligands",
"Signal transduction"
] |
13,319,101 | https://en.wikipedia.org/wiki/Baorangia%20bicolor | Baorangia bicolor, also known as the two-colored bolete or red and yellow bolete after its two-tone coloring scheme, is an edible fungus in the genus Baorangia. It inhabits most of eastern North America, primarily east of the Rocky Mountains, and is in season during the summer and fall months, but can also be found in China and Nepal. Its fruit body, the mushroom, is classed as medium or large in size, which helps distinguish it from the many similar appearing species that have a smaller stature. A deep blue/indigo bruising of the pore surface and a less dramatic bruising coloration change in the stem over a period of several minutes are identifying characteristics that distinguish it from the similar poisonous species Boletus sensibilis. There are two variations of this species, variety borealis and variety subreticulatus, and several other similar species of fungi are not poisonous.
Taxonomy and naming
Baorangia bicolor was originally named in 1807 by the Italian botanist Giuseppe Raddi. American mycologist Charles Horton Peck named a species collected in Sandlake, New York, in 1870, Boletus bicolor. Although this naming is considered illegitimate due to article 53.1 of the International Code of Botanical Nomenclature, Peck is still given as the authority in the Bessette et al. (2000) monograph of North American boletes. Boletus bicolor (Raddi) is not a synonym of "Boletus bicolor" Peck. Peck's Boletus bicolor describes the Eastern North American species that is the familiar "two-colored bolete", while Raddi's Boletus bicolor describes a separate European species that is lost to science. This taxonomic conflict has yet to be resolved. In 1909 a species found in Singapore was named Boletus bicolor by George Edward Massee; this naming is illegitimate and is synonymous with Boletochaete bicolor according to Singer. Molecular studies found that Boletus bicolor was not closely related to the type species of Boletus, Boletus edulis, and in 2015 Alfredo Vizzini transferred Boletus bicolor to the genus Baorangia. The original botanical name for this two-colored bolete was derived from the Latin words bōlētus, meaning "mushroom", and bicolor, meaning "having two colors."
Description
The color of the cap of the two-colored bolete varies from light red and almost pink to brick red. The most common coloration is brick red when mature. The cap usually ranges from to in width, with bright yellow pores underneath. The two-colored bolete is one of several types of boletes that have the unusual reaction of the pore surface producing a dark blue/indigo when it is injured, although the reaction is slower than with other bluing boletes. When the flesh is exposed it also turns a dark blue, but less dramatically than the pore surface. Young fruit bodies have bright yellow pore surfaces that slowly turn a dingy yellow in maturity.
The stem of the two-colored bolete ranges from to in length and ranges from to in width. The stem coloration is yellow at the apex and a red or rosy red for the lower two thirds. When injured it bruises blue very slowly and may hardly change color at all in some cases. The stem lacks a ring and lacks a partial veil.
Microscopic characteristics
The spore deposit of the two-colored bolete is olive-brown. Viewed with a microscope, the spores are slightly oblong to ventricose in face view; in profile view, the spores are roughly inequilateral to oblong, and have a shallow suprahilar depression. The spores appear nearly hyaline (translucent) to pale dingy ochraceous when mounted in potassium hydroxide solution (KOH), have a smooth surface, and measure 8–12 by 3.5–5 μm. The tube trama is divergent and gelatinous, originates from a single central strand, not amyloid, and will often stain yellow-brown when placed in dilute potassium hydroxide (KOH).
Chemical tests
Further methods of identification are chemical tests. With the application of FeSO4 to the cap cuticle (pileipellis), it will turn a dark grey, almost black color and with the application of potassium hydroxide or NH4OH it has a negative coloration. The context stains a bluish grey to an olive green when FeSO4 is applied to it, a pale orange to a pale yellow with the application of KOH, and negative with the application of NH4OH.
Edibility
The two-colored bolete is an edible mushroom, although some may have an allergic reaction after ingestion that results in stomach upset. The mushroom has a very mild to no taste although it is said to have a very distinctive taste like that of the king bolete. It can be cooked several ways, and the varying color of the cap can be used to determine if the mushroom is ready to be eaten. If the cap is a lighter red, then it is less mature and is in a stage where it is often larva infested or it can be soft fleshed, in some cases both. The cap should have a dark brick red color when safe to eat. Drying the two-colored bolete is a good method for storage. It is important to note the time it takes for the two-colored bolete to bruise when identifying it for consumption; the mushroom should take several minutes to bruise compared to the instant bruising of Boletus sensibilis, which is poisonous and has many of the same visual characteristics of the two-colored bolete.
Distribution and habitat
The two-colored bolete is distributed from southeastern Canada and the Great Lakes Region, primarily east of the Rocky Mountains, as far south as the Florida peninsula, and out to the Midwest as far as Wisconsin. It is commonly found in deciduous woodland and usually grows under or close to broad-leaved trees, especially oak. It can be found in isolation and in groups or clusters, primarily during June through October. The two-colored bolete is also found in China and Nepal, where it is one of the most used mushrooms of over 200 species of edible mushrooms used in Nepal. This unusual distribution of the two-colored bolete and other mushrooms is known as the Grayan disjunction; the phenomenon is characterized by a species living in one continent or island and then also on the other side of the world with no specimens of the species living in between the specific habitats. The Grayan disjunction is not uncommon among fungi.
Similar species
The two-colored bolete has several species that are similar to it and the differences are minute in most cases. Boletus sensibilis differs from the two-colored bolete in that it has an immediate bruising reaction and is poisonous, causing stomach upset if ingested, and in some cases a severe allergic reaction. B. miniato-olivaceus has a full yellow stem and slightly lighter cap coloration. It also has a more immediate bruising reaction than the two-colored bolete and the stem is slightly longer in proportion to the cap. B. peckii differs from the two-colored bolete by having a smaller average size, a rose red cap that turns almost brown with age, flesh that is paler in color, and a bitter taste. B. speciosus differs from the two-colored bolete by having a fully reticulated stem, more brilliant colors, and very narrow cylindrical spores. Hortiboletus rubellus subsp. rubens and the two-colored bolete have been found to have almost no difference between them, and they cannot be distinguished by appearance alone. Boletus bicoloroide is very similar to the two-colored bolete, the major differences between them being B. bicoloroide has only been found in Michigan and has larger spores. B. bicoloroide is also slightly larger than the two-colored bolete, around longer in the stem and in the cap. This species has not been as thoroughly researched as the two-colored bolete, thus macrochemical tests, edibility, distribution range, and the spore print color are all unknown.
Varieties
There are two varieties of the two-colored bolete: borealis and subreticulatus. Both varieties have a very similar habitat to that of the main species, except they appear to be limited to just the North American continent. Both varieties also have a slightly different coloration than that of the two-colored bolete, have deeper pores, and are not as often eaten or used in regional recipes.
Variety borealis
Variety borealis has a slightly darker color scheme than the main species. The coloration in general is darker; the cap can vary from a bright apple red to a dark brick red with maturity, to almost purple in some instances. The pore surface has a varying coloration of orange red to red and becoming a dull brown red with age. The bruising coloration is a blue green and the spore print is olive brown. The distribution of variety borealis is relatively small, ranging from Michigan to the upper New England states. The similar distribution and coloration to Boletus carminiporus has caused the two to be confused. New molecular evidence shows that borealis is not closely related to Baorangia bicolor var. bicolor.
Variety subreticulatus
Variety subreticulatus, like variety borealis, has a generally darker coloration than the two-colored bolete, but varies much more than either. When fresh the coloration of the cap varies from a rose red, red, rose pink, dark red, and purple red. With age it changes to a cinnamon red or a rusty rose color, with yellowing toward the margin. The pore surface is similar to that of the main species–yellow when fresh and with age changing to a dull ochre yellow; the bruising coloration is blue but is much lighter and sometimes not appearing to stain when bruised at all. The spore print is olive brown. The distribution of variety subreticulatus is very similar to the distribution of the two-colored bolete in North America, and appears north to eastern Canada and south to Florida, and west to Wisconsin.
See also
List of North American boletes
References
Bibliography
External links
YouTube Video:Foraging, Boletus sensibilis and Boletus bicolor by Bill Yule, Connecticut Valley Mycological Society
article 53.1 of the International Code of Botanical Nomenclature
Boletaceae
Edible fungi
Fungi described in 1807
Fungi of North America
Fungus species | Baorangia bicolor | [
"Biology"
] | 2,184 | [
"Fungi",
"Fungus species"
] |
13,320,206 | https://en.wikipedia.org/wiki/Vapor%E2%80%93liquid%20separator | In chemical engineering, a vapor–liquid separator is a device used to separate a vapor–liquid mixture into its constituent phases. It can be a vertical or horizontal vessel, and can act as a 2-phase or 3-phase separator.
A vapor–liquid separator may also be referred to as a flash drum, breakpot, knock-out drum or knock-out pot, compressor suction drum, suction scrubber or compressor inlet drum, or vent scrubber. When used to remove suspended water droplets from streams of air, it is often called a demister.
Method of operation
In vapor-liquid separators gravity is utilized to cause the denser fluid (liquid) to settle to the bottom of the vessel where it is withdrawn, less dense fluid (vapor) is withdrawn from the top of the vessel.
In low gravity environments such as a space station, a common liquid separator will not function because gravity is not usable as a separation mechanism. In this case, centrifugal force needs to be utilised in a spinning centrifugal separator to drive liquid towards the outer edge of the chamber for removal. Gaseous components migrate towards the center.
An inlet diffuser reduces the velocity and spreads the incoming mixture across the full cross-section of the vessel. A mesh pad in the upper part of the vessel aids separation and prevents liquid from being carried over with the vapor. The pad or mist mat traps entrained liquid droplets and allows them to coalesce until they are large enough to fall through the up-flowing vapor to the bottom of the vessel. Vane packs and cyclonic separators are also used to remove liquid from the outlet vapor.
The gas outlet may itself be surrounded by a spinning mesh screen or grating, so that any liquid that does approach the outlet strikes the grating, is accelerated, and thrown away from the outlet.
The vapor travels through the gas outlet at a design velocity which minimises the entrainment of any liquid droplets in the vapor as it exits the vessel.
A vortex breaker on the liquid outlet prevents the formation of vortices and of vapor being drawn into the liquid outlet.
Liquid level monitoring
The separator is only effective as long as there is a vapor space inside the chamber. The separator can fail if either the mixed inlet is overwhelmed with supply material, or the liquid drain is unable to handle the volume of liquid being collected. The separator may therefore be combined with some other liquid level sensing mechanism such as a sight glass or float sensor. In this manner, both the supply and drain flow can be regulated to prevent the separator from becoming overloaded.
Applications
Vertical separators are generally used when the gas-liquid ratio is high or gas volumes are high. Horizontal separators are used where large volumes of liquid are involved.
A vapor-liquid separator may operate as a 3-phase separator, with two immiscible liquid phases of different densities. For example natural gas (vapor), water and oil/condensate. The two liquids settle at the bottom of the vessel with oil floating on the water. Separate liquid outlets are provided.
The feed to a vapor–liquid separator may also be a liquid that is being partially or totally flashed into a vapor and liquid as it enters the separator.
A slug catcher is a type of vapor–liquid separator that is able to receive a large inflow of liquid at random times. It is usually found at the end of gas pipelines where condensate may be present as slugs of liquid. It is usually a horizontal vessel or array of large diameter pipes.
The liquid capacity of a separator is usually defined by the residence time of the liquid in the vessel. Some typical residence times are as shown.
Where vapor–liquid separators are used
Vapor–liquid separators are very widely used in a great many industries and applications, such as:
Oil refineries
Offshore platforms
Natural-gas processing plants (NGL)
Petrochemical and chemical plants
Refrigeration systems
Air conditioning
Compressor systems
Gas pipelines
Steam condensate flash drums
Geothermal power plants
Combined cycle power plants
Flare stacks
Soil vapor extraction
Paper mills
Liquid ring pumps
Preventing pump damage
In refrigeration systems, it is common for the system to contain a mixture of liquid and gas, but for the mechanical gas compressor to be intolerant of liquid.
Some compressor types such as the scroll compressor use a continuously shrinking compression volume. Once liquid completely fills this volume the pump may either stall and overload, or the pump chamber may be warped or otherwise damaged by the fluid that can not fit into a smaller space.
See also
Flash evaporation
Vapor-compression refrigeration
Souders–Brown equation (for sizing vapor–liquid separators)
Steam drum
References
External links
Experimental Characterization of High-Pressure Natural Gas Scrubbers by Trond Austrheim (preprints of papers based on PhD Thesis at the University of Bergen, Norway, 2006)
Flash Steam Tutorial The benefits of recovering flash steam, how it is done and typical applications.
Quick Calculator for Horizontal Knock Out Drum sizing Based on minimum time required for liquid droplets of a given minimum size to be separated.
Design Criteria for Vapor/Liquid Separators
Detailed explanation of high performance vapor-liquid separators (scrubbers)
Vapor Liquid Separator designs and manufacturing process
Chemical equipment
Oil refineries
Natural gas technology
Heating, ventilation, and air conditioning
Industrial equipment
Gas-liquid separation
Gas technologies | Vapor–liquid separator | [
"Chemistry",
"Engineering"
] | 1,137 | [
"Separation processes by phases",
"Chemical equipment",
"Oil refineries",
"Petroleum",
"Natural gas technology",
"Oil refining",
"nan",
"Gas-liquid separation"
] |
13,320,316 | https://en.wikipedia.org/wiki/Ozsv%C3%A1th%E2%80%93Sch%C3%BCcking%20metric | The Ozsváth–Schücking metric, or the Ozsváth–Schücking solution, is a vacuum solution of the Einstein field equations. The metric was published by István Ozsváth and Engelbert Schücking in 1962. It is noteworthy among vacuum solutions for being the first known solution that is stationary, globally defined, and singularity-free but nevertheless not isometric to the Minkowski metric. This stands in contradiction to a claimed strong Mach principle, which would forbid a vacuum solution from being anything but Minkowski without singularities, where the singularities are to be construed as mass as in the Schwarzschild metric.
With coordinates , define the following tetrad:
It is straightforward to verify that e(0) is timelike, e(1), e(2), e(3) are spacelike, that they are all orthogonal, and that there are no singularities. The corresponding proper time is
The Riemann tensor has only one algebraically independent, nonzero component
which shows that the spacetime is Ricci flat but not conformally flat. That is sufficient to conclude that it is a vacuum solution distinct from Minkowski spacetime. Under a suitable coordinate transformation, the metric can be rewritten as
and is therefore an example of a pp-wave spacetime.
References
Exact solutions in general relativity
General relativity | Ozsváth–Schücking metric | [
"Physics",
"Mathematics"
] | 283 | [
"Exact solutions in general relativity",
"Mathematical objects",
"Equations",
"General relativity",
"Theory of relativity"
] |
13,321,717 | https://en.wikipedia.org/wiki/Active%20tip-clearance%20control | Active clearance control (ACC) is a method used in large aircraft gas turbines to improve fuel efficiency during cruise. This is achieved by setting the turbine tip clearance at more than one operating point and contrasts with passive clearance control which sets it for only one condition and is explained below.
As one way to reduce fuel consumption better blade tip sealing has taken on a prominent role in aircraft engine design since the late 1960's. It is used on the CFM International CFM56-5B engine, installed on the Airbus A320, for example.
Background
Blade tip sealing has been a challenging problem since the development of the gas turbine engine. It is such because the clearance between the blade tips and surrounding casing (shroud) tends to vary due primarily to changes in thermal and mechanical loads on the rotating (turbine wheel) and stationary (stator, turbine casing) structures.
Turbine tip clearance is a leakage path for gas which doesn't flow past the turbine blade aerofoil so doesn't contribute to the power developed by the turbine. As such it reflects a waste of fuel (reduced fuel efficiency). The clearance depends on the thermal growth of a thick-section turbine disc compared to a thin-section turbine case, and also disc radial growth with speed. The three vary, and hence tip clearance, with the engine running condition and clearance is a minimum when the engine first accelerates from idle to take-off, it hasn't had a chance to heat up evenly from being cold at idle although the bladed turbine disc is at maximum speed and so has maximum radial growth from the centrifugal stresses. The thermal effects take longer to stabilize at a steady temperature, ie to give an unvarying tip clearance. This transient condition which gives a minimum clearance is known as a pinch point. The setting of the clearance when the engine is built such that the blade tips don't rub the stationary shrouds in the turbine case at a pinch point condition may be known as passive clearance control.
HPT (high pressure turbine) blade tip clearance has a significant impact on fuel burn and emissions so using ACC gives significant benefits in cruise fuel burn, range, and payload capability for long range aircraft.
Basic system overview
As an example the CFM International CFM56-5A engine active clearance control uses HPC air for the HPTACC and fan bypass air for the LPTACC. Clearance control is managed by the engine FADEC which consists of an electronic control unit (ECU), an hydromechanical unit (HMU) and HP and LP ACC valves.
References
https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20050238447.pdf
Notes
Gas turbine technology
Turbofan engines
Turbines | Active tip-clearance control | [
"Chemistry"
] | 566 | [
"Turbines",
"Turbomachinery"
] |
13,324,152 | https://en.wikipedia.org/wiki/Tygon%20tubing | Tygon® is a brand name for a family of flexible polymer tubing consisting of a variety of materials to be used "across a range of specialized fluid transfer requirements". The specific composition of each type is a trade secret. Some variants have multiple layers of different materials. Tygon is a registered trademark of Saint-Gobain Corporation. It is an invented word, owned and used by Saint-Gobain and originated in the late 1930s. Tygon products are produced in three countries, but sold throughout the world. Tygon tubing is used in many markets, including food and beverage, chemical processing, industrial, laboratory, medical, pharmaceutical, and semiconductor processing. There are many formulations of clear, flexible, Tygon tubing. The chemical resistance and physical properties vary among the different formulations, but the tubing generally is intended to be "so resistant to chemical attack that it will handle practically any chemical", whether liquid, gas, or slurry. While largely non-reactive, Tygon has been reported to liberate carbon monoxide and is listed among carbon monoxide-releasing molecules.
Formulations and applications
Food and beverage applications
Tygon B-44-3, Tygon B-44-4X, Tygon B-44-4X I.B., and Tygon Silver (antimicrobial) were widely used in the food and beverage industry, in particular in: beverage dispensing, dairy processing, soft-serve dispensing, vitamin and flavor concentrate systems, cosmetic production, and water purification systems. These formulations each meet U.S. Food and Drug Administration 3-A and NSF International 51 criteria but they do not comply with European Directives (European Directive 2002/72/EC of 6 August 2002 relating to plastic materials and articles intended to come into contact with foodstuffs as modified in particular by Directive 2007/19/EC of 2 April 2007).
Class VI approved
Several formulations of Tygon are USP class VI approved and can be used in either surgical procedures or pharmaceutical processing.
Medical
Tygon Medical/Surgical Tubing S-50-HL — Characterized to the latest ISO 10993 standards and U.S. Food and Drug Administration (FDA) guidelines for biocompatibility. This material is non-toxic, non-hemolytic, and non-pyrogenic. This formulation is used in minimally invasive devices, dialysis equipment, for bypass procedures, and chemotherapy drug delivery.
Tygon Medical Tubing S-54-HL was introduced in 1964 for use in medical applications. This material can be used in catheters, for intravenous or intra-arterial infusion and other surgical uses. Tygon S-54-HL can also be fabricated into cannulae or protective sheath products using thermoforming and flaring techniques.
Pharmaceutical
Tygon LFL (Long Flex Life) pump tubing is non-toxic clear tubing with broad chemical resistance. It is often used in product filtration and fermentation and surfactant delivery.
Tygon 2275 High Purity Tubing is a plasticizer-free material that is often used in sterile filling and dispensing systems and diagnostic equipment. This formulation is also considered to have low absorption/adsorption properties, which minimizes the risk of fluid alteration.
Tygon 2275 I.B. High-Purity Pressure Tubing is plasticizer-free and is reinforced with a braid for use with elevated working pressures.
Peristaltic pumps
Many formulations of Tygon can be used in peristaltic pumps, including the following:
Tygon R-3603 Laboratory Tubing is commonly used in chemical laboratories. It is often used in incubators and as a replacement for rubber tubing for Bunsen burners. This material is produced in vacuum sizes and can withstand a full vacuum at room temperature. It is a thermoplastic PVC-based material with plasticizer.
Tygon R-1000 Ultra-Soft Tubing is used in general laboratory applications. It is the softest of the Tygon formulations with a durometer hardness of Shore A 40 (ASTM Method D2240-02). Because of the low durometer of this material it is often used in low-torque peristaltic pumps.
Tygon LFL (Long Flex Life) Pump Tubing, Tygon 3350, Tygon S-50-HL Medical/Surgical Tubing, Tygon 2275 High Purity Tubing, and Tygon 2001 Tubing are also used in peristaltic pump applications.
Plasticizer-free/non-DEHP
Tygon tubing is available in Plasticizer-free/non-DEHP (non-Phthalate)-formulations. These formulations have a high degree of chemical resistance and do not release any hazardous material when properly incinerated. Tygon 2275 High Purity tubing, Tygon Ultra Chemical Resistant Tubing 2075, and Tygon Plasticizer Free Tubing 2001 are all plasticizer-free. "ND-100 series" products are non-DEHP and use a non-Phthalate plasticizer.
Tygon Silver Tubing has a plasticizer-free inner bore and a silver-based compound on the inner surface to decrease bacterial growth and protect against microbes.
Industrial use
There are several formulations of Tygon that are used in industrial applications.
Tygon Fuel and Lubricant Tubing F-4040-A is translucent yellow for positive identification and flow monitoring. It is used in small engine fuel lines, recreational vehicles, and lubrication lines.
Tygon LP1100 is a low permeation EPA and CARB certified fuel line also used in small engines.
Tygon R-3400 UV Resistant Tubing is black in color and opaque. It remains flexible in ultraviolet (UV) environments and is often used for electrical insulation, ink, and adhesive dispensing, and fertilizer and pesticide dispensing. Because it is resistant to UV light, ozone, and weathering, it is commonly used in outdoor applications.
Tygon 2075 Ultra Chemical Resistant Tubing is a plasticizer-free material that is known for its high degree of chemical resistance. It can be used in ink and printing fluid dispensing, paint and solvent production, and is resistant to MEK and other chemicals. When properly incinerated it releases only carbon dioxide and water.
Tygon 2375 Ultra Chemical Resistant Tubing is now replacing Tygon 2075.
References
External links
Saint-Gobain Industrial and Consumer Solutions Website
Flared tubing Web site
Industrial equipment
Saint-Gobain | Tygon tubing | [
"Engineering"
] | 1,368 | [
"nan"
] |
13,324,782 | https://en.wikipedia.org/wiki/Project%20engineering | Project engineering includes all parts of the design of manufacturing or processing facilities, either new or modifications to and expansions of existing facilities. A "project" consists of a coordinated series of activities or tasks performed by engineers, designers, drafters and others from one or more engineering disciplines or departments. Project tasks consist of such things as performing calculations, writing specifications, preparing bids, reviewing equipment proposals and evaluating or selecting equipment and preparing various lists, such as equipment and materials lists, and creating drawings such as electrical, piping and instrumentation diagrams, physical layouts and other drawings used in design and construction. A small project may be under the direction of a project engineer. Large projects are typically under the direction of a project manager or management team. Some facilities have in house staff to handle small projects, while some major companies have a department that does internal project engineering. Large projects are typically contracted out to engineering companies. Staffing at engineering companies varies according to the work load and duration of employment may only last until an individual's tasks are completed.
Overview
Responsibilities
The role of the project engineer can often be described as that of a liaison between the project manager and the technical disciplines involved in a project. The distribution of "liaising" and performing tasks within the technical disciplines can vary wildly from project to project; this often depends on the type of product, its maturity, and the size of the company, to name a few. It is important for a project engineer to understand that balance. The project engineer should be knowledgeable enough to be able to speak intelligently within the various disciplines, and not purely be a liaison. The project engineer is also often the primary technical point of contact for the consumer.
A project engineer's responsibilities include schedule preparation, pre-planning and resource forecasting for engineering and other technical activities relating to the project, and project delivery management. They may also be in charge of performance management of vendors. They assure the accuracy of financial forecasts, which tie-in to project schedules. They ensure projects are completed according to project plans. Project engineers manage project team resources and training and develop extensive project management experience and expertise.
Engineering companies
When used, an engineering company is generally contracted to conduct a study (capital cost estimate or technical assessment) or to design a project. Projects are designed to achieve some specific objective, ranging in scope from simple modifications to new factories or expansions costing hundreds of millions or even billions of dollars. The client usually provides the engineering company with a scoping document listing the details of the objective in terms of such things as production rate and product specifications and general to specific information about processes and equipment to be used and the expected deliverables, such as calculations, drawings, lists, specifications, schedules, etc. The client is typically involved in the entire design process and makes decisions throughout, including the technology, type of equipment to use, bid evaluation and supplier selection, the layout of equipment and operational considerations. Depending on the project the engineering company may perform material and energy balances to size equipment and to quantify inputs of materials and energy (steam, electric power, fuel). This information is used to write specifications for the equipment. The equipment specifications are sent out for bids. The client, the engineering company or both select the equipment. The equipment suppliers provide drawings of the equipment, which are used by the engineering company's mechanical engineers, and drafters to make general arrangement drawings, which show how the pieces of equipment are located in relation to other equipment. Layout drawings show specific information about the equipment, electric motors powering the equipment and such things as auxiliary equipment (pumps, fans, air compressors), piping and buildings. The engineering company maintains an equipment list with major equipment, auxiliary equipment, motors, etc. Electrical engineers are involved with power supply to motors and equipment. Process engineers perform material and energy balances and design the piping and instrumentation diagrams to show how equipment is supplied with process fluids, water, air, gases, etc. and the type of control loops used. The instrumentation and controls engineers specify the instrumentation and controls and handle any computer controls and control rooms. Civil and structural engineers deal with site layout and engineering, building design and structural concerns like foundations, pads, structures, supports and bracing for equipment. Environmental engineers deal with any air emissions and treatment of liquid effluent.
Fields and topics
The various fields and topics that projects engineers are involved with include:
Work breakdown structure: a deliverable-oriented breakdown of a project into smaller components
Gantt chart: type of bar chart that illustrates a project schedule
Critical Path Analysis: an algorithm for scheduling a set of project activities
Program evaluation and review technique: a statistical tool which was designed to analyze and represent the tasks involved in completing a given project
Graphical Evaluation and Review Technique: network analysis technique that allows probabilistic treatment both network logic and estimation of activity duration
Petri Nets: one of several mathematical modeling languages for the description of distributed systems
Construction industry
Project engineers are often project managers with qualifications in engineering or construction management. Other titles include field engineer, construction engineer, or construction project engineer. In smaller projects, this person may also be responsible for contracts and will be called an assistant project manager. A similar role is undertaken by a client's engineer or owner's engineer, but by inference, these often act more in the interests of the commissioning company.
Project engineers do not necessarily do design work, but instead represent the contractor or client out in the field, help tradespeople interpret the job's designs, ensure the job is constructed according to the project plans, and assist project controls, including budgeting, scheduling, and planning. In some cases a project engineer is responsible for assisting the assigned project manager with regard to design and a project and with the execution of one or more simultaneous projects in accordance with a valid, executed contract, per company policies and procedures and work instructions for customized and standardized plants.
Typical responsibilities may include: daily operations of field work activities and organization of subcontractors; coordination of the implementation of a project, ensuring it is being built correctly; project schedules and forecasts; interpretation of drawings for tradesmen; review of engineering deliverables; redlining drawings; regular project status reports; budget monitoring and trend tracking; bill of materials creation and maintenance; effective communications between engineering, technical, construction, and project controls groups; and assistance to the project manager.
Further reading
Frederick B. Plummer Jr. (2011), Project Engineering, Butterworth-Heinemann
Anastasia Pagnoni (2012), Project Engineering: Computer-Oriented Planning and Operational Decision Making, Springer
References
External links
Project Engineer Career Description
IAPMO website
IAPMO Codes website
Project management
Engineering disciplines
Construction and extraction occupations | Project engineering | [
"Engineering"
] | 1,356 | [
"nan"
] |
13,325,194 | https://en.wikipedia.org/wiki/Carbonates%20on%20Mars | The formation of carbonates on Mars have been suggested based on evidence of the presence of liquid water and atmospheric carbon dioxide in the planet's early stages. Moreover, due to their utility in registering changes in environmental conditions such as pH, temperature, fluid composition, carbonates have been considered as a primary target for planetary scientists' research. However, since their first detection in 2008, the large deposits of carbonates that were once expected on Mars have not been found, leading to multiple potential explanations that can explain why carbonates did not form massively on the planet.
Mars probes
Previously, most remote sensing instruments such as OMEGA and THEMIS—sensitive to infrared emissivity spectral features of carbonates—had not suggested the presence of carbonate outcrops, at least at the 100 m or coarser spatial scales available from the returned data.
Though ubiquitous, a 2003 study of carbonates on Mars showed that they are dominated by magnesite (MgCO3) in Martian dust, had mass fractions less than 5%, and could have formed under current atmospheric conditions. Furthermore, with the exception of the surface dust component, by 2007 carbonates had not been detected by any in situ mission, even though mineralogic modeling did not preclude small amounts of calcium carbonate in Independence class rocks of Husband Hill in Gusev crater. (note: An IAU naming convention within Gusev is not yet established).
Remote sensing data
The first successful identification of a strong infrared spectral signature from surficial carbonate minerals of local scale (< 10 km2) was made by the MRO-CRISM team in 2008. Spectral modeling in 2007 identified a key deposit in Nili Fossae dominated by a single mineral phase that was spatially associated with olivine outcrops. The dominant mineral appeared to be magnesite, while morphology inferred with HiRISE and thermal properties suggested that the deposit was lithic. Stratigraphically, this layer appeared between phyllosilicates below and mafic cap rocks above, temporally between the Noachian and Hesperian eras. Even though infrared spectra are representative of minerals to less than ≈0.1 mm depths (in contrast to gamma spectra which are sensitive to tens of cm depths), stratigraphic, morphologic, and thermal properties are consistent with the existence of the carbonate as outcrop rather than alteration rinds. Nevertheless, the morphology was distinct from typical terrestrial sedimentary carbonate layers suggesting formation from local aqueous alteration of olivine and other igneous minerals. However, key implications were that the alteration would have occurred under moderate pH and that the resulting carbonates were not exposed to sustained low pH aqueous conditions even as recently as the Hesperian.
Evidence for widespread presence of carbonates began to increase in 2009, when low levels (<10%) of Mg-rich carbonates were found across the Martian area of Syrtis Major, Margaritifer Terra, Lunae Planum, Elysium Planitia, as reported from analysis of data acquired by the Planetary Fourier Spectrometer (PFS) on board the Mars Express spacecraft.
When the Thermal and Evolved Gas Analyzer (TEGA) and WCL experiments on the 2009 Phoenix Mars lander found between 3–5wt% calcite (CaCO3) and an alkaline soil. In 2010 analyses by the Mars Exploration Rover Spirit, identified outcrops rich in magnesium-iron carbonate (16–34 wt%) in the Columbia Hills of Gusev crater, most likely precipitated from carbonate-bearing solutions under hydrothermal conditions at near-neutral pH in association with volcanic activity during the Noachian era.
After Spirit Rover stopped working scientists studied old data from the Miniature Thermal Emission Spectrometer, or Mini-TES and confirmed the presence of large amounts of carbonate-rich rocks, which means that regions of the planet may have once harbored water. The carbonates were discovered in an outcrop of rocks called "Comanche."
Carbonates (calcium or iron carbonates) were discovered in a crater on the rim of Huygens Crater, located in the Iapygia quadrangle. The impact on the rim exposed material that had been dug up from the impact that created Huygens. These minerals represent evidence that Mars once had a thicker carbon dioxide atmosphere with abundant moisture. These kind of carbonates only form when there is a lot of water. They were found with the Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) instrument on the Mars Reconnaissance Orbiter. Earlier, the instrument had detected clay minerals. The carbonates were found near the clay minerals. Both of these minerals form in wet environments. It is supposed that billions of years age Mars was much warmer and wetter. At that time, carbonates would have formed from water and the carbon dioxide-rich atmosphere. Later the deposits of carbonate would have been buried. The double impact has now exposed the minerals. Earth has vast carbonate deposits in the form of limestone.
Absence of carbonates on Mars
Geological and geomorphological evidence has reinforced the idea of the presence of liquid water on early Mars. Therefore, abundant precipitation of carbonates from atmospheric and water reactions is expected. However, spectral imaging has revealed only small amounts of carbonates, generating doubts about humans' understanding of geological processes on Mars. To overcome this problem, scientists have proposed explanations that reconcile the absence of carbonates with the presence of a CO2-rich atmosphere and liquid water.
Cold and dry early Martian environments
According to this explanation, the early Martian conditions are similar to those at present. Essentially, it suggests that carbonates are absent because the planet never experienced conditions that included the presence of liquid water and a CO2-rich thick atmosphere. Even if this explanation provides an insight in the reasons why carbonates are not present, it is in disagreement with the geomorphological and mineralogical evidence supporting the existence of liquid water on Mars' surface.
Inability of detection with current technology
This hypothesis establishes that the Thermal Emission Spectrometer (TES) aboard the Mars Global Surveyor spacecraft and the Thermal Emission Imaging System (THEMIS) on board the Mars Odyssey spacecraft are unable to detect carbonates. According to this notion, the carbonates indeed formed and are still exist on Mars, but they remain undetected due to the limited sensitivity of the current tools used for mineralogical detection on the planet.
Secondary chemical alteration
This concept involves the potential for secondary chemical alteration of ancient carbonates on Mars, due to the formation of acid rain resulting from the combination of water vapor and sulfates. The consequence of this process implies the chemical decomposition of superficial carbonates layers, as carbonates are not resistant to acidic pH conditions; acid-fog weathering; and photo-decomposition.
Hidden carbonate deposits
According to this perspective, massive carbonates deposits formed but are hidden beneath several layers of secondary alteration rocks, preventing their identification on the surface. Other alternatives to this hypothesis include: Masking of carbonates as a consequence of the abundant soils on Mars; and resurfacing processes that have covered carbonate deposits, such as eolian deposition and late sedimentation processes.
Inhibition due to acidic conditions
Finally, this hypothesis defends the idea that carbonates never precipitated because the pH conditions of the environment were too acidic to allow carbonates to precipitate, or at least siderite, which is the primary carbonate mineral expected to precipitate first. The acidic conditions are derived from the high partial pressures of atmospheric carbon dioxide, as well as a persistent sulfate and iron enrichment that affect the optimal conditions for carbonates to precipitate.
Gallery
See also
References
Rocks on Mars
Mars
Planetary science | Carbonates on Mars | [
"Astronomy"
] | 1,572 | [
"Planetary science",
"Astronomical sub-disciplines"
] |
13,326,000 | https://en.wikipedia.org/wiki/MainStage%20%28software%29 | MainStage is a music application developed by Apple Inc. designed for use in live performance.
Features
MainStage works in a similar way and has a similar user interface to Logic Pro, although the focus is on live use rather than features like recording and editing that are available in a DAW such as Logic. Instead of a timeline for instance, there is an editable "Workspace". This allows a user to drag out an object that acts as a software representation of a hardware controller like a button, knob or fader and assign that to a parameter such as volume, pan or even more complex things.
MainStage comes bundled with a number of sampled software instruments (such as pianos, guitars, drum kits and pads) as well as effects. These instruments can be played using a pre-recorded MIDI file or via a controller device that uses the MIDI protocol, such as a keyboard or drum pad. It can also act as a "host" and centralize any third-party virtual instruments or audio units that users might have installed on their computers. Virtual instruments that can be used with MainStage can also be used with Logic Pro.
A MainStage concert can display a patch list which displays all the patches created by a user for that concert. Each patch might have a different instrument or effect assigned to it and various parameters can be changed during a performance by cycling through the list.
Other features include:
Recording of any audio signal passing through.
Multi-effects processing for external inputs (e.g. a guitar or a microphone/vocals).
Playback of pre-recorded backing tracks.
MIDI transformation via MIDI FX plugins and routing via external instrument channel strips.
Release history
The first version of MainStage was introduced on September 12, 2007, alongside Logic Studio.
The second version, MainStage 2, was released on July 23, 2009, along with updated releases of many of the other applications in the Logic Studio package. Version 2.1 released in January 2010, introduced a 64-bit mode. Since version 2.2, updates are available only from the Mac App Store.
MainStage 3 was released alongside Logic Pro X on July 16, 2013, as a paid update and available only as a download from the Mac App Store. There is a free iPad companion app available designed for use with Logic Pro X, MainStage 3 and GarageBand, which can act as a hardware controller for various parameters.
With the release of the version 3.5 on November 12, 2020, the long-standing compatibility with OS X 10.9 or later was dropped due to the new requirement of Metal; MainStage became only available for 10.15 or later. With the release of the version 3.6 on March 14, 2022, MainStage was only available for Big Sur and Monterey. As of version 3.6.5 released in November 2023, support for Monterey is dropped and the software is only available for Ventura (13.5 or later) and Sonoma.
See also
Logic Pro
GarageBand
Ableton Live
References
External links
MainStage Webpage
Logic Pro Webpage
Logic Remote Webpage
Apple Inc. software
Audio software | MainStage (software) | [
"Engineering"
] | 641 | [
"Audio engineering",
"Audio software"
] |
13,326,175 | https://en.wikipedia.org/wiki/List%20of%20local%20winds | This is a list of names given to winds local to specific regions.
Africa
Berg wind, a seasonal katabatic wind blowing down the Great Escarpment from the high central plateau to the coast in South Africa.
Cape Doctor, often persistent and dry south-easterly wind that blows on the South African coast from spring to late summer (September to March in the southern hemisphere).
Haboob, a sandstorm's fast moving wind which causes cold temperature over the area from where it passes. It mainly passes through Sudan.
Harmattan, a dry wind that blows from the northeast, bringing dust from the Sahara south toward the Gulf of Guinea.
Khamsin (khamaseen in Egypt) and similar winds named Haboob in the Sudan, Aajej in southern Morocco, Ghibli in Libya and Tunisia, Harmattan in the western Maghreb, Sirocco, a south wind from the Sahara and Simoom in the Arabian Peninsula.
Tsiokantimo (strong south wind blowing southwest Madagascar)
Asia
Central Asia
Karaburan ("power storm") (a spring and winter katabatic wind of Central Asia)
Khazri (cold, coastal gale-force wind of north Caspian Sea)
Sukhovey (hot dry wind in the steppes, semi-deserts, and deserts of the Kazakhstan and the Caspian region)
Eastern Asia
Buran (a wind which blows across eastern Asia. It is also known as Purga when over the tundra)
Karakaze (strong cold mountain wind from Gunma Prefecture in Japan)
East Asian Monsoon, known in China and Taiwan as meiyu (), in Korea as jangma (장마), and in Japan as when advancing northwards in the spring and when retreating southwards in autumn.
(strong katabatic wind across the Kanto Plain)
Northern Asia
Barguzin wind (steady, strong wind on Lake Baikal in Russia)
Sarma (cold strong wind at the western shore of Lake Baikal)
Southeast Asia
Amihan (northeasterly wind across the Philippines)
(southwesterly wind across the Philippines)
Southern Asia
Elephanta (strong southerly or southeasterly wind on the Malabar coast of India)
Norwester or Kalbaishakhi (local rain fall and thunder storm which occurs in India and Bangladesh)
Kali Andhi or simply Andhi (the violent dust squalls that occur before monsoon in the northwestern parts of the Indo-Gangetic Plain region of the Indian Subcontinent)
Loo (hot wind which blows over plains of India and Pakistan.)
Mango showers (it is accompanied by thunderstorm bringing rainfall to Karnataka, Kerala and parts of Tamil Nadu during months of March and April.)
Pachua (Westerlies)
Monsoon of South Asia
Western Asia
Gilavar (south wind in the Absheron Peninsula of the Azerbaijan Republic)
N'aschi (northeastern wind on the Iranian coast of the Persian Gulf, and on the Makran coast)
Rashabar (or Rashaba) ("black wind") (a strong wind in the Kurdistan Region of Iraq, particularly in Sulaimaniya)
Shamal (a summer northwesterly wind blowing over Iraq and the Persian Gulf states)
Sharqi (seasonal dry, dusty Middle Eastern wind coming from the south and southeast)
Simoom (Samiel) (strong, dry, desert wind that blows in Israel, Jordan, Syria, and the desert of Arabia)
Wind of 120 days (a four-month-long hot and dry wind over the Sistan Basin in Iran and Afghanistan)
The Americas
Latin America and the Caribbean
Caribbean
Alisio (easterly trade wind in the Caribbean)
Alize (northeasterly across Central America and the Caribbean)
Bayamo (violent wind on Cuba's southern coast)
Brisote (the northeast trade wind when it is blowing more strongly than usual, in Cuba)
Mexico
Cordonazo, also referred to as el cordonazo de San Francisco or the Lash of St Francis (southerly hurricane winds along the west coast of Mexico)
Coromuel (south to south-west wind in the La Paz area of the Baja California peninsula and the Gulf of California)
Norte (strong cold northeasterly wind in Mexico)
Central America
Papagayo (periodic wind which blows across Nicaragua and Costa Rica and out over the Gulf of Papagayo)
Tehuantepecer, or Tehuano wind (periodic wind which blows across the Isthmus of Tehuantepec in southern Mexico and out over the Gulf of Tehuantepec)
South America
Abrolhos (squall near the Abrolhos Islands off the coast of eastern Brazil)
Caju (stormy gale-force north-westerly in the Atlantic coast of Brazil)
Nordeste (moderate wind from northwest in brazilian Northeast region)
Carpinteiro (strong southeasterly wind along the southern Atlantic coast of Brazil)
Garua, la garúa, or garoa (dry winds hitting the lower western slopes of the Andes)
Minuano (southern Brazil)
Zonda wind (on the eastern slope of the Andes in Argentina)
Pampero (Argentina and Uruguay), very strong wind that blows from the sea over the Rio de la Plata into the Pampa, generally accompanied with a thick line of squalls, with severe rains, hail and thunderstorm.
Puelche (on the western slope of the Andes in south-central Chile)
Sudestada, (strong offshore wind from the Southeast associated with most of the shipwrecks in Uruguay's Rio de la Plata coast)
Williwaw (strong, violent wind occurring in the Strait of Magellan, the Aleutian Islands, and the coastal fjords of Southeast Alaska)
North America
Alberta Clipper (fast-moving, frigid winter wind out of the central Canadian plains that swoops down across the U.S. Plains, Midwest and Great Lakes)
Brookings Effect (off-shore wind on the southwestern Oregon coast, United States; also known as the Chetco Effect)
Chinook (warm dry westerly off the Rocky Mountains)
Diablo (hot, dry, offshore wind from the northeast in the San Francisco bay)
The Hawk (cold winter wind in Chicago)
Jarbo Gap Wind (associated with and often referred to as a Diablo Wind; katabatic winds in the Northern Sierra Nevada in the vicinity of Jarbo Gap, often contributing to the growth of local wildfires)
Montreal Express (an arctic cold air mass that sweeps across New England sometimes as far as Massachusetts... the term seems to be regional to New England)
Nigeq (a strong wind from the east in Greenland)
Nor'easter (strong storm with winds from the northeast on the north eastern coast of the United States (particularly New England states) and the east coast of Canada (Atlantic Canada))
Texas Norther (fast-moving, stormy Arctic cold front that strikes Texas in winter, dropping freezing rain or sleet, a.k.a. Blue Norther because it sometimes appears as a low, blue, dense advancing cloud)
Piteraq (cold katabatic wind on the Greenlandic east coast)
Plough Wind (straight line wind which precedes thunderstorms or thunderstorm clusters)
Santa Ana winds (dry downslope winds that affect coastal Southern California and northern Baja California)
Santa Lucia winds (a downslope wind affecting southern San Luis Obispo and northern Santa Barbara Counties, California)
Squamish (strong, violent wind occurring in many of the fjords of British Columbia)
Les Suêtes (western Cape Breton Highlands) high speed southeasterly winds
Sundowner, (strong offshore wind off the California coast)
Washoe Zephyr (seasonal diurnal wind in parts of western Nevada)
Williwaw (strong, violent wind occurring in the Strait of Magellan, the Aleutian Islands, and the coastal fjords of Southeast Alaska)
Witch of November, or November Witch (strong winds blowing across the Great Lakes in autumn)
Wreckhouse (strong downslope winds off the Long Range Mountains in south-western Newfoundland)
Europe
(cold and usually strong northerly or northeasterly wind in Italy)
(warm, föhn-type southeasterly wind in the Mediterranean Languedoc region)
Bise (cold, northern wind in France and northeastern wind in Switzerland)
Böhm (cold, dry wind in Central Europe)
Bora (northeasterly from eastern Europe to northeastern Italy and northwestern Balkans)
Burle (north wind which blows in the winter in south-central France)
Cers (strong, very dry northeasterly wind in the bas-Languedoc region in southern France)
Cierzo (cool north/northwesterly wind on Ebro Valley in Spain)
Crivăț (strong, very cold north-easterly wind in Moldavia, Dobruja, and the Bărăgan Plain parts of Romania.)
Etesian (Greek name) or Meltem (Turkish name) (northerly across Greece and Turkey)
(a warm and usually moderate wind from Africa that reaches the Ionian coast of Italy)
Euroclydon (a cyclonic tempestuous northeast wind in the Mediterranean)
Föhn or foehn (a warm, dry, southerly wind off the northern side of the Alps and North Italy. The name gave rise to the fén-fēng (焚風 'burning wind') of Taiwan).
Gregale (northeasterly from Greece)
Halny (in northern Carpathians)
Helm (north-easterly wind in Cumbria, England)
Košava (strong and cold southeasterly season wind in Serbia)
Viento de Levante or Levanter (easterly through Strait of Gibraltar)
Leste (hot, dry, easterly wind of the Madeira and Canary Islands)
Leveche (Spanish name for a warm southwest wind in parts of coastal Mediterranean Spain)
Libeccio (southwesterly towards Italy)
Llevantades (north-north-east and east-north-east on the east coast of Spain)
Lodos (southwesterly towards Turkey. Strong "Lodos" events occur 6 - 7 times a year bringing 35 kt winds into Marmara Sea. The winds are funnelled SE from the Mediterranean and through the Dardanelles Strait.)
Maestro (cold northerly in the Adriatic Sea)
Marin (south-easterly from Mediterranean to France)
Mistral (cold northerly from central France and the Alps to Mediterranean)
Nordés (north-eastern wind in Galicia)
Ostro (southerly wind in the Mediterranean)
Poniente, ponente, or ponent (strong west to east wind formed by the wind tunnel effect of the Gibraltar Strait; see Levante for the opposite)
Sirocco (southerly warm and moist wind from north Africa to southern Europe, mostly to Southern Italy and to the Balkans)
Solano (south to south-easterly wind in the southern sector of Spain)
Tramontane (cold northwesterly from the Pyrenees or northeasterly from the Alps to the Mediterranean, similar to Mistral)
Vendavel (westerly through the Strait of Gibraltar)
Murlan (cold and dry northeasterly wind in winter in Albania, Montenegro and Northwestern part of North Macedonia)
Winds of Provence
Oceania
Australia
Black nor'easter (violent north-easterly storm that occurs on the east coast of Australia usually between late spring and early autumn)
Brickfielder (hot and dry wind in Southern Australia)
Fremantle Doctor (afternoon sea breeze from the Indian Ocean which cools Perth, Western Australia during summer)
Southeast Australian foehn (a westerly föhn wind that affects southeastern Australia)
Southerly buster (rapidly arriving low pressure cell that dramatically cools southeast Australian cities such as Sydney and Melbourne during summer)
Hawaii
Kona (southeast wind in Hawaii, replacing trade winds, bringing high humidity and often rain)
New Guinea
Warm Braw (föhn wind in the Schouten Islands, north of New Guinea)
New Zealand
Kaimai Breeze (turbulent wind with strong downdrafts in the Kaimai Range of North Island, New Zealand)
Nor'wester (wind that brings rain to the West Coast, and warm dry winds to the East Coast of New Zealand's South Island, caused by the moist prevailing winds being uplifted over the Southern Alps, often accompanied by a distinctive arched cloud pattern)
References
Winds | List of local winds | [
"Physics"
] | 2,522 | [
"Weather",
"Physical phenomena",
"Weather-related lists"
] |
13,326,250 | https://en.wikipedia.org/wiki/Telugu%20Ganga%20project | {
"type": "ExternalData",
"service": "page",
"title": "TeluguGanga.map"
}
The Telugu Ganga project is a joint water supply scheme implemented in India in 1980s by the then Andhra Pradesh chief minister Nandamuri Taraka Rama Rao and Tamil Nadu chief minister Maruthur Gopalan Ramachandran to provide drinking water to Chennai City in Tamil Nadu. It is also known as the Krishna Water Supply Project, since the source of the water is the Krishna River in erstwhile Andhra Pradesh. Water is drawn from the Srisailam reservoir and diverted towards Chennai through a series of interlinked canals, over a distance of about , before it reaches the destination at the Poondi reservoir near Chennai. The main checkpoints en route include the Somasila reservoir in Penna River valley, the Kandaleru reservoir, the 'Zero Point' near Uthukkottai where the water enters Tamil Nadu territory and finally, the Poondi reservoir, also known as Satyamurthy Sagar. From Poondi, water is distributed through a system of link canals to other storage reservoirs located at Red Hills, Sholavaram and Chembarambakkam.
The project was approved in 1977 after an agreement was reached between Tamil Nadu and the riparian states of Krishna River: Andhra Pradesh, Maharashtra and Karnataka. According to the agreement, each of the three riparian states were to contribute of water annually, for a total supply of .
This number was revised down to in 1983 after accounting for seepage and evaporation losses.
The water initially supplied by the canal was disappointing, delivering less than . In 2002, the religious leader Sathya Sai Baba announced a scheme of restoration and lining of the canal; a private undertaking. With an extensive rebuilding of the canal and several reservoirs, the project was completed in 2004, when the Poondi reservoir received Krishna water for the first time.
The supply of water to Chennai city in 2006 was .
After the re-lining and reconstruction, the Kandaleru-Poondi part of the canal was renamed Sai Ganga.
Jerdon's Courser
The area has however continued to be threatened by illegal construction work and activity related to a project proposed to link the rivers of India.
Notes
References
Geography of Chennai
Interbasin transfer
Water supply infrastructure in India
Canals in Tamil Nadu
Year of establishment missing | Telugu Ganga project | [
"Environmental_science"
] | 488 | [
"Hydrology",
"Interbasin transfer"
] |
13,326,263 | https://en.wikipedia.org/wiki/DISC1 | Disrupted in schizophrenia 1 is a protein that in humans is encoded by the DISC1 gene. In coordination with a wide array of interacting partners, DISC1 has been shown to participate in the regulation of cell proliferation, differentiation, migration, neuronal axon and dendrite outgrowth, mitochondrial transport, fission and/or fusion, and cell-to-cell adhesion. Several studies have shown that unregulated expression or altered protein structure of DISC1 may predispose individuals to the development of schizophrenia, clinical depression, bipolar disorder, and other psychiatric conditions. The cellular functions that are disrupted by permutations in DISC1, which lead to the development of these disorders, have yet to be clearly defined and are the subject of current ongoing research. Although, recent genetic studies of large schizophrenia cohorts have failed to implicate DISC1 as a risk gene at the gene level, the DISC1 interactome gene set was associated with schizophrenia, showing evidence from genome-wide association studies of the role of DISC1 and interacting partners in schizophrenia susceptibility.
Discovery
In 1970, researchers from the University of Edinburgh performing cytogenetic research on a group of juvenile offenders in Scotland found an abnormal translocation in chromosome 1 of one of the boys, who also displayed characteristics of an affective psychological disorder. After this initial observation, the boy's family was studied and it was found that 34 out of 77 family members displayed the same translocation. According to the Diagnostic and Statistical Manual of Mental Disorders (Fourth Edition) (or DSM-IV) criteria, sixteen of the 34 individuals identified as having the genetic mutation were diagnosed with psychiatric problems. In contrast, five of the 43 unaffected family members were identified to have psychological indispositions. The psychiatric illnesses observed in the family ranged from schizophrenia and major depression to bipolar disorder and adolescent conduct disorder (which the original research subject had). After studying this large Scottish family for four generations, in 2000, this gene was given the name "DISC1". The name was derived from the basis of the molecular nature of the mutation: the translocation directly disrupts the gene.
Importance of genetic studies
The implication of genetics in psychiatric illnesses is not unique to schizophrenia, though the heritability of schizophrenia has been calculated as high as 80%. The continued research of the family following the discovery of the translocation yielded statistical analysis of the probability of observing the simultaneous occurrence, or co-inheritance, of psychological conditions and the translocation. This concept was measured quantitatively using the LOD, or logarithm of the odds value. The higher the LOD value, the stronger the correlation between the presence of the translocation and given disease(s) is thought to be. The LOD for the chromosome 1 translocation and identification of schizophrenia alone in the Scottish family was found to be 3.6. The LOD value of the translocation and a broader number of diagnoses (including schizophrenia, schizoaffective disorder, bipolar affective disorder, and recurrent major depression) was found to be 7.1.
Besides large familial-based studies in which the pedigrees of various family members are examined, twin studies have also been a source of support for researchers in the investigation of DISC1. In a meta-analysis of twin studies, twelve out of fourteen were found to support the fact that from a genetic perspective, schizophrenia is a complex trait that depends on both genetic and environmental factors. Such findings have encouraged researchers to continue with both macro-analysis of the disorders affecting individuals with the mutation, as well as explore the micro-level.
Gene location and transcription
The DISC1 gene is situated at chromosome 1q42.1 and overlaps with DISC2 open reading frame. Multiple DISC1 isoforms have been identified at the RNA level, including a TSNAX-DISC1 transgene splice variant, and at the protein level. Of the isolated RNA isomers, 4 have been confirmed to be translated namely Long form (L), Long variant isoform (Lv), Small isoform (S), and Especially small isoform (Es). Human DISC1 is transcribed as two major splice variants, L form and Lv isoform. The L and Lv transcripts utilize distal and proximal splice sites, respectively, within exon 11. The L and Lv protein isoforms differ by only 22 amino acids within the C-terminus.
Alternate transcriptional splice variants, encoding different isoforms, have been characterized.
DISC1 homologues have been identified in all major vertebrate families including the common chimpanzee, the rhesus monkey, the house mouse, the brown rat, zebrafish, pufferfish, cattle, and dogs; additionally homologue's have been described for invertebrate and plant phyla.
Protein structure and subcellular distribution
The protein encoded by this gene is predicted to contain a coiled coil motif rich C-terminal domain, and a N-terminal globular domain. The N-terminus contains two putative nuclear localization signals, and a serine-phenylalanine-rich motif of unknown significance. The C-terminus contains multiple regions with coiled-coil forming potential, and two leucine zippers that may mediate protein-protein interactions.
The protein locates to the nucleus, centrosome, cytoplasm, mitochondria, axons and synapses. Mitochondria are the predominant site of endogenous DISC1 expression, with at least two isoforms occupying internal mitochondrial locations. No known functional homologues exist for this protein in humans, although it does have broad homology to scaffold proteins. The DISC1 protein function appears to be highly diverse and its functional role in cellular processes is dependent upon the cellular domain it is located in. The presence or absence of certain protein interaction domains or targeting motifs may confer specific functions and influence sub cellular targeting, therefore it is probable that alternative splicing codetermines both the function and the intracellular location of DISC1.
Function
Many studies have provided insight into the normal function of the DISC1 protein, though much remains to be clearly defined. DISC1 is functionally involved in several processes that regulate neural development and brain maturation such as neuronal proliferation, differentiation, migration, cAMP signaling, cytoskeletal modulation, and translational regulation via various signaling pathways. Much of what is understood about the normal function of DISC1 has been uncovered through studies on zebrafish and mice as model organisms. In zebrafish, DISC1 is essential for forebrain development and GSK3/β-catenin signaling, while in mice the DISC1-GSK3 pathway regulates proliferation of neural progenitor cells in the cortex and adult dentate gyrus. This data suggests a direct DISC1 GSK3/β-catenin interaction.
DISC1 functions through a rich protein-protein interaction network, named the "DISC1 interactome" by researchers. Among its known interaction partners are 14-3-3ε, LIS1 and the PDE4B enzyme. DISC1 may play an important role in neuroplasticity via interactions with molecules of the cytoskeleton and centrosome, such as NUDEL and LIS1. The protein also enables the activity of dynein, a microtubule protein. Controlling transport of microtubules is involved in neuronal migration, neurite outgrowth, and axon formation.
DISC1 is highly expressed during critical periods of brain development, particularly in the embryonic ventricular and subventricular zones of the cortex, where neural progenitor cells are found. This localization suggests that DISC1 is an important regulator of embryonic and adult neurogenesis, and may regulate proliferation and/or differentiation. Levels of the protein in cycling neural progenitor cells affects whether they differentiate into neurons or remain as progenitors. Expression profile is highest in the hippocampus during development and remains highly expressed in the adult dentate gyrus and olfactory bulb, regions where adult neurogenesis is present. DISC1 has also been shown to regulate tempo of neuronal integration into the brain and guidance of positioning of new neurons.
Due to localization of the protein found at the synapse, DISC1 is also likely to play a key role in postsynaptic density, however this novel role is not yet fully understood.
Protein interactions
The DISC1 protein has no known enzymatic activity; rather it exerts its effect on multiple proteins through interactions to modulate their functional states and biological activities in time and space. These include:
DISC1
DISC1 has been shown to self-associate, to form dimers, multimers, and oligomers. The ability of DISC1 to form complexes with itself may be important in regulating its affinity for interacting partners such as NDEL1. In postmortem brain samples of Schizophrenia patients there is an increase in insoluble DISC1 oligomer aggregates, indicative of a common link with other neurological disorders characterised by protein aggregation, namely Alzheimer's disease, Parkinson's disease, and Huntington's disease.
ATF4/ATF5
ATF4 and ATF5 are members of the leucine zipper activating transcription factor / CREB family. They are known to bind to and regulate the function of GABAB receptors in synapses and are involved in signal transduction from the cell membrane to the nucleus. Both proteins interact with DISC1 and GABAB receptors via their second C-terminal leucine zipper domain, therefore DISC1 is able to regulate GABAB receptor function through its interaction with ATF4/ATF5.
FEZ1
DISC1 participates in neurite outgrowth through its interaction with the fasciculation and elongation protein ζ-1 (FEZ1). FEZ1 is a mammalian homolog of the C. elegans UNC-76 protein involved in axonal outgrowth and fasciculation. The C-terminal region of FEZ1 (aa 247–392) is required for interaction with DISC1. A DISC1 region (aa 446–633), containing two stretches with coiled-coil-forming potential is critical for its interaction with FEZ1. DISC1-FEZ1 interaction is enhanced during neuro-differentiation, and expression of the FEZ1-binding domain of DISC1 has a dominant negative effect on neurite outgrowth, which implies co-operation of DISC1 and FEZ1 in this process.
Kalirin-7
The DISC1 protein plays a role in the process of regulating spine form and function through its interactions with kalirin-7 (kal-7). Kal-7 is a regulator of spine morphology and synaptic plasticity in association with neuronal activity. Kal-7-dependent regulation of spine formation occurs through its activity as a GDP/GTP exchange factor for Rac1. Activation of rac1 by kal-7 leads to increased spine size and synaptic strength through regulation of the actin cytoskeleton by rac1. DISC1 is able to bind to kal-7, confining its access to rac1, and in turn regulate spinal formation. Activation of NMDA receptors causes dissociation of DISC1 and kal-7, leaving kal-7 available to activate rac1.
MAP1A
DISC1 shows strong interaction with the microtubule-associated protein MAP1A that controls the polymerization and stabilization of microtubule networks in neurons, and thereby influence cell shape and intracellular transport of vesicles and organelles. MAP1A binds to the far N-terminus (aa 293–696) of DISC1, and the amino terminus of DISC1 binds to the LC2 subunit of MAP1A. The LC2 subunit of MAP1A contains an actin-binding domain and is necessary and sufficient for microtubule binding and polymerization, therefore DISC1 is able to regulate the ability of MAP1A to polymerize and stabilize microtubules and traffic proteins to their correct localization in the synaptic architecture.
NDEL1/NUDEL
DISC1 is localized to the centrosome, the primary microtubule organizing center of the cell, via interaction with nuclear distribution gene homologue-like 1 (NDEL1, also called NUDEL), where it is part of a protein complex involved in cytoskeletal processes of neuronal migration, including nucleokinesis and neurite outgrowth. NUDEL is also known to play a role in axon regeneration and has an additional DISC1-modulated function as a cysteine endopeptidase. Localization of NUDEL to axons is dependent on expression of DISC1. NUDEL binds to a 100 amino acid domain of DISC1 (aa 598–697) containing a coiled coil domain and a leucine zipper. The amino acid domain of NUDEL that binds DISC1 is the carboxyl terminal 100 amino acids of the protein (aa 241–345), which contains a cytoplasmic dynein binding site.
PCM1/Pericentriolar material
The protein Pericentriolar Material 1 (PCM1) which is associated with cilia development in the CNS interacts directly with the Disrupted-In-Schizophrenia 1 (DISC1) and calmodulin 1 (CALM1) proteins. Kamiya et al. have shown that PCM1, DISC1 and BBS4 can all disrupt neuronal organisation in the mouse when their expression is down-regulated. Markers at the pericentriolar material 1 gene (PCM1) have shown genetic association with schizophrenia in several schizophrenia case control studies. Resequencing of the genomic DNA from research volunteers who had inherited haplotypes associated with schizophrenia showed a threonine an isoleucine mis-sense mutation in exon 24 which may change the structure and function of PCM1 (rs370429). This mutation was found only as a heterozygote in ninety eight research subjects with schizophrenia and controls out of a total sample of 2,246 case and control research subjects. Amongst the ninety eight carriers of rs370429 sixty seven were affected with schizophrenia. The same alleles and haplotypes were associated with schizophrenia in both London and Aberdeen samples. Another potential aetiological base pair change in PCM1 was rs445422 which altered a splice site signal. A further mutation, rs208747, was shown by electrophoretic mobility shift assays to create or destroy a promoter transcription factor site. Five further non-synonymous changes in exons were also found. Given the number and identity of the haplotypes associated with schizophrenia further aetiological base pair changes must exist within and around the PCM1 gene. The findings in relation to PCM1 support the role of DISC1 also being a susceptibility locus for schizophrenia.
Other interactions include: ACTN2, CEP63, EIF3A, RANBP9, and SPTBN4.
Clinical implications
Aberrations of DISC1 are considered a generalized risk factor in major psychiatric diseases and have also been implicated in memory deficits and abnormal patterns of brain activity. DISC1 translocation increases the risk of developing schizophrenia, bipolar disorder, or major depression by about 50-fold in comparison to the general population. Efforts to model DISC1 disease biology in transgenic mice, Drosophila, and zebrafish have provided psychiatric disease implications related to DISC1 mutations. However, no specific variant is consistently associated with development of mental disorders, indicating allelic heterogeneity in psychiatric disease. The impact of variants in the DISC1 gene on expression and protein function is not yet clearly defined and associated variants are not necessarily causative.
Schizophrenia
Schizophrenia affects 1% of the general population and is highly heritable, providing an indication of a genetic basis. DISC1 has been associated with neurological abnormalities such as delusions, deficits in long term and working memory, diminution of gray matter volume in hippocampal and prefrontal regions. These abnormalities are also seen as symptoms of schizophrenia. As DISC1 function is involved in neurogenesis and neuroplasticity, vulnerability to schizophrenia may involve dysfunction in the hippocampus, a brain region in which adult neurogenesis occurs. Mice expressing the dominant-negative form of DISC1 have been shown to be increasingly susceptible to impaired reality testing, a hallmark of psychosis.
Autism and Asperger's syndrome
In 2008, a genetic screen of 97 Finnish families affected by autism and Asperger's syndrome revealed repeated DNA sequences within the DISC1 gene in those diagnosed with autism. Furthermore, a single nucleotide change in the gene was found to be present in 83% of family members with Asperger's syndrome. A recent family study has reported a large chromosome 1 deletion that includes loss of DISC1 in a young boy diagnosed with autism. A link between DISC1 duplication and autism has also been suggested by the finding of a seven-gene duplication that includes DISC1 carried by two brothers with autism and mild retardation. These alterations in people with the disorder are rare, however, as none were found in a screening of 260 Belgians with autism.
Transgenic model organism strains generated with mutated or absent DISC1 suggest that the gene may contribute to at least some autistic abnormalities. Mice with lowered levels of DISC1 expression exhibit abnormal response to electrical stimulation, a decrease of dopamine synthesis, and an inability to filter unnecessary sensory information. Studies of expression of mutant DISC1 prenatally and postnatally have demonstrated varying effects, indicating the possibility that early postnatal expression of mutant DISC1 causes features of autism. Many more studies are necessary to confirm these suggestions.
Bipolar disorder
Linkage studies in extended families multiply affected with bipolar disorder also provide evidence for DISC1 as a genetic factor in the etiology of bipolar disorder. In 1998, a follow-up study was conducted of the large Scottish family in which DISC1 was first discovered. Additional family members with the original translocation who developed major psychotic illness, including bipolar disorder, were identified.
Research directions
As DISC1 investigation continues to be an emerging area of study, many unanswered questions regarding the biological function of the protein and its implications in psychiatric disorders remain. In depth understanding of DISC1 as a genetic risk factor for psychiatric disorders provides a possible target for developing new drug therapies and preventative measures. The pathways regulated by DISC1 interaction may provide possible avenues for therapeutic opportunities to reverse related deficits. Definitive genetic architecture, risk distribution, and their correlation with prognosis is crucial to determining response to new drug treatments.
In addition to DISC1, the antisense partner has been identified as DISC2, a noncoding RNA gene that may be involved in regulating the gene locus. However, structure and function of DISC2 remain unknown and may provide insight into how DISC1 is regulated.
Rare mutations in DISC1 other than the original translocation have been discovered and require further investigation. Furthermore, posttranslational processing and its effect on isoform expression, which also contributes to protein function and may be involved in some forms of disease, remains to be studied. The ability to predict the impact of different types of mutations on protein function and resulting psychiatric phenotype is crucial for the development of targeted treatments.
Family studies continue to provide an important approach towards deepening understanding of the biological nature of the gene and its clinical implications. While the original Scottish family in which DISC1 was discovered is still being considered, other familial populations in different countries have also become the focus of research in the past decade. In 2005, an American family was found to also possess a frameshift mutation in the DISC1 gene, which again co-segregated with schizophrenia and schizoaffective disorder. Characterized by a deletion of four base-pairs, the mutation was found in two siblings, one with schizophrenia and the other with schizoaffective disorder. Similar studies have also been done with Taiwanese and Finnish families.
References
Further reading
External links
Proteins
Molecular neuroscience
Biology of bipolar disorder | DISC1 | [
"Chemistry"
] | 4,199 | [
"Molecular neuroscience",
"Biomolecules by chemical classification",
"Proteins",
"Molecular biology"
] |
10,832,165 | https://en.wikipedia.org/wiki/D-17B | The D-17B (D17B) computer was used in the Minuteman I NS-1OQ missile guidance system. The complete guidance system contained a D-17B computer, the associated stable platform, and power supplies.
The D-17B weighed approximately , contained 1,521 transistors, 6,282 diodes, 1,116 capacitors, and 5094 resistors. These components were mounted on double copper-clad, engraved, gold-plated, glass fiber laminate circuit boards. There were 75 of these circuit boards and each one was coated with a flexible polyurethane compound for moisture and vibration protection. The high degree of reliability and ruggedness of the computer were driven by the strict requirements of the weapons system.
Design constraints
High reliability was required of the D-17B. It controlled a key weapon that would have just one chance to execute its mission. Reliability of the D-17B was achieved through the use of solid-state electronics and a relatively simple design. Simpler DRL (diode–resistor) logic was used extensively, while less-reliable DTL (diode–transistor) logic (which provides gain and inversion) was used only where needed. In the late 1950s and early 1960s, when the D-17B was designed, transistors lacked today's reliability. Reliability was also enhanced by the rotating-disk memory with non-destructive readout (NDRO). In actual real-time situations, Minuteman missiles achieved a mean time between failures (MTBF) of over 5.5 years .
The Soviets had much larger rockets and could use vacuum tubes in their guidance systems. The Minuteman I, II and III weighed 29,500 kg, 31,746 kg and 35,000 kg respectively, versus the Soviet R-7 missile (1959) at 280,000 kg. The US planners had to choose either to develop solid state guidance systems (which weigh less) or consider the additional cost and time delay of developing larger rockets.
Specifications
Minuteman I D-17B computer specifications
Year: 1962
The D17B is a synchronous serial general-purpose digital computer.
Manufacturer:
Autonetics Division of North American Aviation
Applications:
Guidance and control of the Minuteman I ICBM.
Programming and numerical system:
Number system: Binary, fixed point, 2's complement
Logic levels: 0 V for logical 0 (false), -10 V for logical 1 (true)
Data word length (bits): 11 or 24 (double precision)
Instruction word length (bits): 24
Binary digits/word: 27
Instructions/word: 1
Instruction type: One and half address
Number of instructions: 39 types from a 4-bit op code by using five bits of the operand address field for instructions which do not access memory.
Execution times in microseconds:
Add: μs
Multiply: μs or μs (double precision)
Divide: (software)
(Note: Parallel processing such as two simultaneous single precision operations is permitted without additional execution time.)
Clock channel: 345.6 kHz
Addressing:
Direct addressing of entire memory
Two-address (unflagged) and three-address (flagged) instruction
Memory:
Word length (bits): 24 plus 5 timing
Type: Ferrous-oxide-coated NDRO disk
Cycle time: μs (minimal)
Capacity (words): 5,454 or 2,727 (double precision)
Input/output:
Input lines: 48 digital
Output lines: 28 digital
12 analog
3 pulse
Program: 800 5-bit char/s
Instruction word format:
+--------+--------+------+--------+---------+--------+--------+
| TP | T24 21 | 20 | 19 13 | 12 8 | 7 1 | 0 |
+--------+--------+------+--------+---------+--------+--------+
| Timing | OP | Flag | Next | Channel | Sector | Timing |
| | | | Inst. | | | |
| | | | Sector | | | |
+--------+--------+------+--------+---------+--------+--------+
Registers:
Phase and voltage output registers
Construction (arithmetic unit only): transistor-diode logic is used.
Timing: Synchronous
Operation: Sequential
Input
48 digital lines (input)
26 specialized incremental inputs
-Medium- -Speed-
Paper/Mylar Tape 600 chars/sec
Keyboard Manual
Typewriter Manual
Output
-Medium- -Speed-
Printer Character 78.5–2,433 ms (Program Control)
Phase - Voltage (Program Control)
28 digital lines (output)
12 analog lines (output)
13 pulse lines (output)
25,600 word/s maximum I/O transfer rate
Physical characteristics
Dimensions: 20 in high, 29 in diameter, 5 in deep
Power: 28 VDC at 25 A
Circuits: DRL and DTL
Weight:
Construction:
Double copper clad, gold plated, glass fiber laminate, flexible polyurethane-coated circuit boards
Software:
Minimal delay coding using machine language
Modular special-purpose subroutines
Reliability: 5.5 years MTBF
Checking features:
Parity on fill and on character outputs
Power, space, weight, and site preparation
Power, computer: 0.25 kW
Air conditioner: Closed system
Volume, computer:
Weight, computer:
Designed specifically to fit in cylindrical guidance package.
The word length for this computer Is 27 bits, of which 24 are used In computation. The remaining 3 bits are spare and synchronizing bits. The memory storage capability consists of a 6000 rpm magnetic disk with a storage capacity of 2985 words of which 2728 are addressable. The contents of memory include 20 cold-storage channels of 128 sectors (words) each, a hot-storage channel of 128 sectors, four rapid access loops (U, F, E, H) of 1, 4, 8, and 16 words respectively, four 1-word arithmetic loops (A, L, H, I), and a two 4-word input buffer input loops (V, R).
The outputs that can be realized from the D-17B computer are binary, discrete, single character, phase register status, telemetry, and voltage outputs. Binary outputs are computer generated levels of +1 or −1 available on the binary output lines.
Instruction set
D-17B Instruction Repertoire
Numeric Code Code Description
------------ ---- -----------
00 20, s SAL Split accumulator left shift
00 22, s ALS Accumulator left shift
00 24, 2 SLL Split left word left shift
00 26, r SLR Split left word right shift
00 30, s SAR Split accumulator right shift
00 32, s ARS Accumulator right shift
00 34, s SRL Split right word left shift
00 36, s SRR Split right word right shift
00 60, s COA Character output A
04 c, S SCL Split Compare and .ivt
10 c, S TMI Transfer on minus
20 c, s SMP Split multiply
24 c, s MPY Multiply
30 c, s SMM Split multiply modified
34 c, s MPM Multiply modified
40 02, s BOC Binary output C
40 10, s BCA Binary output A
40 12, s BOB Binary output B
40 20, s RSD Reset detector
40 22, s HPR Halt and Proceed
40 26, s DOA Discrete output A
40 30, s VOA Voltage output A
40 32, s VOB Voltage output B
40 34, s VOC Voltage output C
40 40, s ANA And to accumulator
40 44, s MIM Minus magnitude
40 46, s COM Complement
40 50, s DIB Discrete input B
40 52, s DIA Discrete input A
40 60, s HFC Halt fine countdown
40 62, s EFC Enter fine countdown
40 70, s LPR Load phase register
44 c, s CIA Clear and Add
50 c, s TRA Transfer
54 c, s STO Store accumulator
60 c, s SAD Split add
64 c, s ADD Add
70 c, s SSU Split subtract
74 c, s SUB Subtract
Special features of the D-17B computer include flag store, split-word arithmetic, and minimized access timing. Flag store provides the capability of storing the present contents of the accumulator while executing the next Instruction. Split-word arithmetic is used in performing arithmetic operations on both halves of a split word at the same time. A split word on the D-17B consists of 11 bits. Minimized access timing is the placing of instructions and data in memory so that they are available with minimum delay from the disk memory.
Guidance software
Autonetics was the associate contractor for the Minuteman (MM) guidance system, which included the flight and prelaunch software. This software was programmed in assembly language into a D17 disk computer. TRW provided the guidance equations that Autonetics programmed and was also responsible for the verification of the flight software. When MM I became operational, the flight computer was the only digital computer in the system. The targeting was done at Strategic Air Command (SAC) Headquarters by the Operational Targeting Program developed by TRW to execute on an IBM 709 mainframe computer.
Sylvania Electronics Systems was selected to develop the first ground-based command and control system using a programmable computer. They developed the software, the message processing and control unit for Wing 6. To support the deployment of the Wing 6 system, TRW, Inc. developed the execution plan program (EPP) from a mainframe computer at SAC and performed an independent checkout of the command and control software. The EPP assisted in assigning targets and launch time for the missiles.
The MM II missile was deployed with a D-37C disk computer. Autonetics also programmed functional simulators and the code inserter verifier that was used at Wing headquarters to generate and test the flight program codes to go into the airborne computer.
Notes
References
Autonetics Division of North American Rockwell. Inc.; Minuteman D-17 Computer Training Data. Anaheim, California, 8 June 1970.
Autonetics Division of North American Rockwell. Inc.; Part I - Preliminary Maintenance Manual of the Minuteman D-17A Computer and Associated Test Equipment. P.O. Memo 71. Anaheim, California, Inc., January 1960.
Beck, C.H. Minuteman Computer Users Group, Report MCUG-l-71. New Orleans, Louisiana: Tulane University, April 1971.
Beck, C.H. Minuteman Computer Users Group. D-17B Computer Programming Manual. Report MCUG-4-71. New Orleans: Tulane University, September 1971.
Beck, Charles H. Investigation of Minuteman D-17B Computer Reutilization. Available from NTIS/DTIC as document AD0722476, January 1971, 54 pp.
Lin, Tony C.; "Development of U.S. Air Force Intercontinental Ballistic Missile Weapon Systems." Journal of Spacecraft and Rockets, vol. 40, no. 4, 2003. pp. 491–509.
See also
D-37C
D37D
External links
Missile guidance
Transistorized computers
Serial computers
Military equipment introduced in the 1960s | D-17B | [
"Technology"
] | 2,463 | [
"Serial computers",
"Computers"
] |
10,832,464 | https://en.wikipedia.org/wiki/Fineness%20ratio | In naval architecture and aerospace engineering, the fineness ratio is the ratio of the length of a body to its maximum width. Shapes that are short and wide have a low fineness ratio, those that are long and narrow have high fineness ratios. Aircraft that spend time at supersonic speeds, e.g. the Concorde, generally have high fineness ratios.
At speeds below critical mach, one of the primary forms of drag is skin friction. As the name implies, this is drag caused by the interaction of the airflow with the aircraft's skin. To minimize this drag, the aircraft should be designed to minimize the exposed skin area, or "wetted surface". One solution to this problem is constructing an "egg shaped" fuselage, for example as used on the home-built Questair Venture.
Theoretical ideal fineness ratios in subsonic aircraft fuselages are typically found at about 6:1, however this may be compromised by other design considerations such as seating or freight size requirements. Because a higher fineness fuselage can have reduced tail surfaces, this ideal ratio can practically be increased to 8:1.
Most aircraft have fineness ratios significantly greater than this, however. This is often due to the competing need to place the tail control surfaces at the end of a longer moment arm to increase their effectiveness. Reducing the length of the fuselage would require larger controls, which would offset the drag savings from using the ideal fineness ratio. An example of a high-performance design with an imperfect fineness ratio is the Lancair. In other cases, the designer is forced to use a non-ideal design due to outside factors such as seating arrangements or cargo pallet sizes. Modern airliners often have fineness ratios much higher than ideal, a side effect of their cylindrical cross-section which is selected for strength, as well as providing a single width to simplify seating layout and air cargo handling.
As an aircraft approaches the speed of sound, shock waves form on areas of greater curvature. These shock waves radiate away energy that the engines must supply, energy that does not go into making the aircraft go faster. This appears to be a new form of drag—referred to as wave drag—which peaks at about three times the drag at speeds even slightly below the critical mach. In order to minimize the wave drag, the curvature of the aircraft should be kept to a minimum, which implies much higher fineness ratios. This is why high-speed aircraft have long pointed noses and tails, and cockpit canopies that are flush to the fuselage line.
More technically, the best possible performance for a supersonic design is typified by two "perfect shapes", the Sears-Haack body which is pointed at both ends, or the von Kármán ogive, which has a blunt tail. Examples of the latter design include the Concorde, F-104 Starfighter and XB-70 Valkyrie, although to some degree practically every post-World War II interceptor aircraft featured such a design. The latter is mostly seen on rockets and missiles, with the blunt end being the rocket nozzle. Missile designers are even less interested in low-speed performance, and missiles generally have higher fineness ratios than most aircraft.
The introduction of aircraft with higher fineness ratios also introduced a new form of instability, inertial coupling. As the engines and cockpit moved away from the aircraft's center of mass with the longer fuselages demanded by the high fineness ratio, the roll inertia of these masses grew to be able to overwhelm the power of the aerodynamic surfaces. A variety of methods are used to combat this effect, including oversized controls and stability augmentation systems.
References
Inline citations
General references
Form Factor
Basic Fluid Dynamics
Aerospace engineering
Aerodynamics
Engineering ratios | Fineness ratio | [
"Chemistry",
"Mathematics",
"Engineering"
] | 763 | [
"Metrics",
"Engineering ratios",
"Quantity",
"Aerodynamics",
"Aerospace engineering",
"Fluid dynamics"
] |
10,832,697 | https://en.wikipedia.org/wiki/Moonstone%20%28gemstone%29 | Moonstone is a sodium potassium aluminium silicate ((Na,K)AlSi3O8) of the feldspar group that displays a pearly and opalescent schiller. An alternative name for moonstone is hecatolite (from goddess Hecate).
Etymology
The name moonstone derives from the stone's characteristic visual effect, called adularescence (or schiller), which produces a milky, bluish interior light. This effect is caused by light diffraction through alternating layers of orthoclase and albite within the stone. The diffracted light varies from white to blue, depending on the thinness of the albite layers. More technically, this micro-structure consists of regular exsolution layers (lamellae) of different alkali feldspars (orthoclase and sodium-rich plagioclase).
Polished moonstones often display chatoyancy ("cat's eye" effect), where a luminous streak appears through the stone. Asterism is rare and produces four-legged stars.
Geology
The most common moonstone is of the orthoclase feldspar mineral adularia, named for an early mining site near Mt. Adular in Switzerland, now the town of St. Gotthard. A solid solution of the plagioclase feldspar oligoclase +/− the potassium feldspar orthoclase also produces moonstone specimens.
Deposits of moonstone occur in Armenia (mainly from Lake Sevan), Australia, the Austrian Alps, Mexico, Madagascar, Myanmar, Norway, Poland, India, Sri Lanka,
and the United States. Historically, the most valuable, transparent moonstones with strong blue sheen came from Myanmar. Today, most commercial moonstones come from Sri Lanka.
In culture
Moonstone has been used in jewellery for millennia, including ancient civilizations. The Romans admired moonstone, as they believed it was derived from solidified rays of the Moon. Both the Romans and Greeks associated moonstone with their lunar deities. In more recent history, moonstone became popular during the Art Nouveau period; French goldsmith René Lalique and many others created a large quantity of jewellery using this stone.
The moonstone is the Florida State Gemstone; it was designated as such in 1970 to commemorate the Moon landings, which took off from Kennedy Space Center. However, it does not naturally occur in the state.
In Thailand, moonstone is known as Mukdahan, the same name as the northeastern province next to the river Mekong, Mukdahan. The name of the province comes from a folklore that a magical gemstone looked like a pearl floating above the Mekong in the area where the province is now located.
See also
Belomorite-moonstone
References
External links
Feldspar
Gemstones
Symbols of Florida | Moonstone (gemstone) | [
"Physics"
] | 583 | [
"Materials",
"Gemstones",
"Matter"
] |
10,833,118 | https://en.wikipedia.org/wiki/NGC%201427A | NGC 1427A, also known as ESO 358-49, or ESO 358- G 049, is an irregular galaxy in the constellation Fornax. Its distance modulus has been estimated using the globular cluster luminosity function to be 31.01 ± 0.21 which is about 52 Mly. It is the brightest dwarf irregular member of the Fornax cluster and is in the foreground of the cluster's central galaxy NGC 1399.
Characteristics and fate
NGC 1427A is over 20,000 light-years long and similar to the Large Magellanic Cloud. The resulting pressure is giving the galaxy its arrowhead outline and triggering the episodes of star formation.
Under the influence of galactic tides, NGC 1427A is travelling into the center of the Fornax cluster with a velocity of approximately 600 km per second. Its distinctive arrowhead shape has been formed by this rapid, upwards movement. The interaction of NGC 1427A with Fornax gasses and galaxies during its journey will cause the disruption of the galaxy within the next billion years, an event which was common during the evolution of the Universe but has become increasingly rare.
Observations
The Hubble Space Telescope's Used Advanced Camera's for Surveys that were used to obtain images of NGC 1427A in visible (green), red, and infrared filters in January 2003. These images were then combined by the Hubble Heritage team to create the color image shown in box. Astronomers are using the data to investigate the star-formation patterns throughout the object, to verify a prediction that there should be a relation between the ages of stars and their positions within the galaxy. This will help them understand how the gravitational influence of the cluster has affected the internal workings of this galaxy, and how this galaxy has responded to passing through the cluster environment. This image was image of the day on March 4, 2005.
Background spiral galaxy
To the upper left of NGC 1427A is a background galaxy that happens to lie near Hubble's line of sight but is some 25 times further away, about 1.3 billion light-years away. In contrast to the irregularly shaped NGC 1427A, the background galaxy is a magnificent spiral, somewhat similar to our own Milky Way. Stars are forming in its symmetric pinwheel-shaped spiral arms, which can be traced into the galaxy's bright nucleus. This galaxy is, however, less dominated by very young stars than NGC 1427A, giving it an overall yellower color. At even greater distances background galaxies of various shapes and colors are scattered across the Hubble image.
References
External links
Barred irregular galaxies
Fornax
1427A
13500
Fornax Cluster
358-49 | NGC 1427A | [
"Astronomy"
] | 553 | [
"Fornax",
"Constellations"
] |
10,833,216 | https://en.wikipedia.org/wiki/Transferability%20%28chemistry%29 | In chemistry, transferability is the assumption that a chemical property that is associated with an atom or a functional group in a molecule will have a similar (but not identical) value in a variety of different circumstances. Examples of transferable properties include:
Electronegativity
Nucleophilicity
Chemical shifts in NMR spectroscopy
Characteristic frequencies in Infrared spectroscopy
Bond length and bond angle
Bond energy
Transferable properties are distinguished from conserved properties, which are assumed to always have the same value whatever the chemical situation, e.g. standard atomic weight.
References
Chemical properties | Transferability (chemistry) | [
"Chemistry"
] | 113 | [
"nan"
] |
10,833,335 | https://en.wikipedia.org/wiki/History%20monoid | In mathematics and computer science, a history monoid is a way of representing the histories of concurrently running computer processes as a collection of strings, each string representing the individual history of a process. The history monoid provides a set of synchronization primitives (such as locks, mutexes or thread joins) for providing rendezvous points between a set of independently executing processes or threads.
History monoids occur in the theory of concurrent computation, and provide a low-level mathematical foundation for process calculi, such as CSP the language of communicating sequential processes, or CCS, the calculus of communicating systems. History monoids were first presented by M.W. Shields.
History monoids are isomorphic to trace monoids (free partially commutative monoids) and to the monoid of dependency graphs. As such, they are free objects and are universal. The history monoid is a type of semi-abelian categorical product in the category of monoids.
Product monoids and projection
Let
denote an n-tuple of (not necessarily pairwise disjoint) alphabets . Let denote all possible combinations of one finite-length string from each alphabet:
(In more formal language, is the Cartesian product of the free monoids of the . The superscript star is the Kleene star.) Composition in the product monoid is component-wise, so that, for
and
then
for all in . Define the union alphabet to be
(The union here is the set union, not the disjoint union.) Given any string , we can pick out just the letters in some using the corresponding string projection . A distribution is the mapping that operates on with all of the , separating it into components in each free monoid:
Histories
For every , the tuple is called the elementary history of a. It serves as an indicator function for the inclusion of a letter a in an alphabet . That is,
where
Here, denotes the empty string. The history monoid is the submonoid of the product monoid generated by the elementary histories: (where the superscript star is the Kleene star applied with a component-wise definition of composition as given above). The elements of are called global histories, and the projections of a global history are called individual histories.
Connection to computer science
The use of the word history in this context, and the connection to concurrent computing, can be understood as follows. An individual history is a record of the sequence of states of a process (or thread or machine); the alphabet is the set of states of the process.
A letter that occurs in two or more alphabets serves as a synchronization primitive between the various individual histories. That is, if such a letter occurs in one individual history, it must also occur in another history, and serves to "tie" or "rendezvous" them together.
Consider, for example, and . The union alphabet is of course . The elementary histories are , , , and . In this example, an individual history of the first process might be while the individual history of the second machine might be . Both of these individual histories are represented by the global history , since the projection of this string onto the individual alphabets yields the individual histories. In the global history, the letters and can be considered to commute with the letters and , in that these can be rearranged without changing the individual histories. Such commutation is simply a statement that the first and second processes are running concurrently, and are unordered with respect to each other; they have not (yet) exchanged any messages or performed any synchronization.
The letter serves as a synchronization primitive, as its occurrence marks a spot in both the global and individual histories, that cannot be commuted across. Thus, while the letters and can be re-ordered past and , they cannot be reordered past . Thus, the global history and the global history both have as individual histories and , indicating that the execution of may happen before or after . However, the letter is synchronizing, so that is guaranteed to happen after , even though is in a different process than .
Properties
A history monoid is isomorphic to a trace monoid, and as such, is a type of semi-abelian categorical product in the category of monoids. In particular, the history monoid is isomorphic to the trace monoid with the dependency relation given by
In simple terms, this is just the formal statement of the informal discussion given above: the letters in an alphabet can be commutatively re-ordered past the letters in an alphabet , unless they are letters that occur in both alphabets. Thus, traces are exactly global histories, and vice versa.
Conversely, given any trace monoid , one can construct an isomorphic history monoid by taking a sequence of alphabets where ranges over all pairs in .
Notes
References
Antoni Mazurkiewicz, "Introduction to Trace Theory", pp. 3–41, in The Book of Traces, V. Diekert, G. Rozenberg, eds. (1995) World Scientific, Singapore
Volker Diekert, Yves Métivier, "Partial Commutation and Traces", In G. Rozenberg and A. Salomaa, editors, Handbook of Formal Languages, Vol. 3, Beyond Words, pages 457–534. Springer-Verlag, Berlin, 1997.
Concurrency (computer science)
Semigroup theory
Formal languages
Free algebraic structures | History monoid | [
"Mathematics"
] | 1,119 | [
"Mathematical structures",
"Formal languages",
"Mathematical logic",
"Fields of abstract algebra",
"Algebraic structures",
"Category theory",
"Semigroup theory",
"Free algebraic structures"
] |
10,833,403 | https://en.wikipedia.org/wiki/Proton%20affinity | The proton affinity (PA, Epa) of an anion or of a neutral atom or molecule is the negative of the enthalpy change in the reaction between the chemical species concerned and a proton in the gas phase:
A- + H+ -> HA
B + H+ -> BH+
These reactions are always exothermic in the gas phase, i.e. energy is released (enthalpy is negative) when the reaction advances in the direction shown above, while the proton affinity is positive. This is the same sign convention used for electron affinity. The property related to the proton affinity is the gas-phase basicity, which is the negative of the Gibbs energy for above reactions, i.e. the gas-phase basicity includes entropic terms in contrast to the proton affinity.
Acid/base chemistry
The higher the proton affinity, the stronger the base and the weaker the conjugate acid in the gas phase. The (reportedly) strongest known base is the ortho-diethynylbenzene dianion (Epa = 1843 kJ/mol), followed by the methanide anion (Epa = 1743 kJ/mol) and the hydride ion (Epa = 1675 kJ/mol), making methane the weakest proton acid in the gas phase, followed by dihydrogen. The weakest known base is the helium atom (Epa = 177.8 kJ/mol), making the hydrohelium(1+) ion the strongest known proton acid.
Hydration
Proton affinities illustrate the role of hydration in aqueous-phase Brønsted acidity. Hydrofluoric acid is a weak acid in aqueous solution (pKa = 3.15) but a very weak acid in the gas phase (Epa (F−) = 1554 kJ/mol): the fluoride ion is as strong a base as SiH3− in the gas phase, but its basicity is reduced in aqueous solution because it is strongly hydrated, and therefore stabilized. The contrast is even more marked for the hydroxide ion (Epa = 1635 kJ/mol), one of the strongest known proton acceptors in the gas phase. Suspensions of potassium hydroxide in dimethyl sulfoxide (which does not solvate the hydroxide ion as strongly as water) are markedly more basic than aqueous solutions, and are capable of deprotonating such weak acids as triphenylmethane (pKa = ca. 30).
To a first approximation, the proton affinity of a base in the gas phase can be seen as offsetting (usually only partially) the extremely favorable hydration energy of the gaseous proton (ΔE = −1530 kJ/mol), as can be seen in the following estimates of aqueous acidity:
These estimates suffer from the fact the free energy change of dissociation is in effect the small difference of two large numbers. However, hydrofluoric acid is correctly predicted to be a weak acid in aqueous solution and the estimated value for the pKa of dihydrogen is in agreement with the behaviour of saline hydrides (e.g., sodium hydride) when used in organic synthesis.
Difference from pKa
Both proton affinity and pKa are measures of the acidity of a molecule, and so both reflect the thermodynamic gradient between a molecule and the anionic form of that molecule upon removal of a proton from it. Implicit in the definition of pKa however is that the acceptor of this proton is water, and an equilibrium is being established between the molecule and bulk solution. More broadly, pKa can be defined with reference to any solvent, and many weak organic acids have measured pKa values in DMSO. Large discrepancies between pKa values in water versus DMSO (i.e., the pKa of water in water is 14, but water in DMSO is 32) demonstrate that the solvent is an active partner in the proton equilibrium process, and so pKa does not represent an intrinsic property of the molecule in isolation. In contrast, proton affinity is an intrinsic property of the molecule, without explicit reference to the solvent.
A second difference arises in noting that pKa reflects a thermal free energy for the proton transfer process, in which both enthalpic and entropic terms are considered together. Therefore, pKa is influenced both by the stability of the molecular anion, as well as the entropy associated of forming and mixing new species. Proton affinity, on the other hand, is not a measure of free energy.
List of compound affinities
Proton affinities are quoted in kJ/mol, in increasing order of gas-phase basicity of the base.
References
Chemical properties | Proton affinity | [
"Chemistry"
] | 1,003 | [
"nan"
] |
10,833,408 | https://en.wikipedia.org/wiki/Helium%20hydride%20ion | The helium hydride ion, hydridohelium(1+) ion, or helonium is a cation (positively charged ion) with chemical formula HeH+. It consists of a helium atom bonded to a hydrogen atom, with one electron removed. It can also be viewed as protonated helium. It is the lightest heteronuclear ion, and is believed to be the first compound formed in the Universe after the Big Bang.
The ion was first produced in a laboratory in 1925. It is stable in isolation, but extremely reactive, and cannot be prepared in bulk, because it would react with any other molecule with which it came into contact. Noted as the strongest known acid—stronger than even fluoroantimonic acid—its occurrence in the interstellar medium had been conjectured since the 1970s, and it was finally detected in April 2019 using the airborne SOFIA telescope.
Physical properties
The helium hydrogen ion is isoelectronic with molecular hydrogen ().
Unlike the dihydrogen ion , the helium hydride ion has a permanent dipole moment, which makes its spectroscopic characterization easier. The calculated dipole moment of HeH+ is 2.26 or 2.84 D. The electron density in the ion is higher around the helium nucleus than the hydrogen. 80% of the electron charge is closer to the helium nucleus than to the hydrogen nucleus.
Spectroscopic detection is hampered, because one of its most prominent spectral lines, at 149.14 μm, coincides with a doublet of spectral lines belonging to the methylidyne radical ⫶CH.
The length of the covalent bond in the ion is 0.772 Å or 77.2 pm.
Isotopologues
The helium hydride ion has six relatively stable isotopologues, that differ in the isotopes of the two elements, and hence in the total atomic mass number (A) and the total number of neutrons (N) in the two nuclei:
or (A = 4, N = 1)
or (A = 5, N = 2)
or (A = 6, N = 3; radioactive)
or (A = 5, N = 2)
or (A = 6, N = 3)
or (A = 7, N = 4; radioactive)
They all have three protons and two electrons. The first three are generated by radioactive decay of tritium in the molecules HT = , DT = , and = , respectively. The last three can be generated by ionizing the appropriate isotopologue of in the presence of helium-4.
The following isotopologues of the helium hydride ion, of the dihydrogen ion , and of the trihydrogen ion have the same total atomic mass number A:
, , , (A = 4)
, , , , (A = 5)
, , , , (A = 6)
, , (A = 7)
The masses in each row above are not equal, though, because the binding energies in the nuclei are different.
Neutral molecule
Unlike the helium hydride ion, the neutral helium hydride molecule HeH is not stable in the ground state. However, it does exist in an excited state as an excimer (HeH*), and its spectrum was first observed in the mid-1980s.
The neutral molecule is the first entry in the Gmelin database.
Chemical properties and reactions
Preparation
Since HeH+ reacts with every substance, it cannot be stored in any container. As a result, its chemistry must be studied by creating it in situ.
Reactions with organic substances can be studied by substituting hydrogen in the desired organic compound with tritium. The decay of tritium to 3He+ followed by its extraction of a hydrogen atom from the compound yields 3HeH+, which is then surrounded by the organic material and will in turn react.
TR → 3He+ + R• (beta decay)
3He+ + HR → 3HeH+ + R• (hydrogen abstraction)
Acidity
HeH+ cannot be prepared in a condensed phase, as it would donate a proton to any anion, molecule or atom that it came in contact with. It has been shown to protonate O2, NH3, SO2, H2O, and CO2, giving , , , H3O+, and respectively. Other molecules such as nitric oxide, nitrogen dioxide, nitrous oxide, hydrogen sulfide, methane, acetylene, ethylene, ethane, methanol and acetonitrile react but break up due to the large amount of energy produced.
In fact, HeH+ is the strongest known acid, with a proton affinity of 177.8 kJ/mol.
Other helium-hydrogen ions
Additional helium atoms can attach to HeH+ to form larger clusters such as He2H+, He3H+, He4H+, He5H+ and He6H+.
The dihelium hydride cation, He2H+, is formed by the reaction of dihelium cation with molecular hydrogen:
+ H2 → He2H+ + H
It is a linear ion with hydrogen in the centre.
The hexahelium hydride ion, He6H+, is particularly stable.
Other helium hydride ions are known or have been studied theoretically. Helium dihydride ion, or dihydridohelium(1+), , has been observed using microwave spectroscopy. It has a calculated binding energy of 25.1 kJ/mol, while trihydridohelium(1+), , has a calculated binding energy of 0.42 kJ/mol.
History
Discovery in ionization experiments
Hydridohelium(1+), specifically , was first detected indirectly in 1925 by T. R. Hogness and E. G. Lunn. They were injecting protons of known energy into a rarefied mixture of hydrogen and helium, in order to study the formation of hydrogen ions like , and . They observed that appeared at the same beam energy (16 eV) as , and its concentration increased with pressure much more than that of the other two ions. From these data, they concluded that the ions were transferring a proton to molecules that they collided with, including helium.
In 1933, K. Bainbridge used mass spectrometry to compare the masses of the ions (helium hydride ion) and (twice-deuterated trihydrogen ion) in order to obtain an accurate measurement of the atomic mass of deuterium relative to that of helium. Both ions have 3 protons, 2 neutrons, and 2 electrons. He also compared (helium deuteride ion) with (trideuterium ion), both with 3 protons and 3 neutrons.
Early theoretical studies
The first attempt to compute the structure of the HeH+ ion (specifically, ) by quantum mechanical theory was made by J. Beach in 1936. Improved computations were sporadically published over the next decades.
Tritium decay methods in chemistry
H. Schwartz observed in 1955 that the decay of the tritium molecule = should generate the helium hydride ion with high probability.
In 1963, F. Cacace at the Sapienza University of Rome conceived the decay technique for preparing and studying organic radicals and carbenium ions. In a variant of that technique, exotic species like methanium are produced by reacting organic compounds with the that is produced by the decay of that is mixed with the desired reagents. Much of what we know about the chemistry of came through this technique.
Implications for neutrino mass experiments
In 1980, V. Lubimov (Lyubimov) at the ITEP laboratory in Moscow claimed to have detected a mildly significant rest mass (30 ± 16) eV for the neutrino, by analyzing the energy spectrum of the β decay of tritium. The claim was disputed, and several other groups set out to check it by studying the decay of molecular tritium . It was known that some of the energy released by that decay would be diverted to the excitation of the decay products, including ; and this phenomenon could be a significant source of error in that experiment. This observation motivated numerous efforts to precisely compute the expected energy states of that ion in order to reduce the uncertainty of those measurements. Many have improved the computations since then, and now there is quite good agreement between computed and experimental properties; including for the isotopologues , , and .
Spectral predictions and detection
In 1956, M. Cantwell predicted theoretically that the spectrum of vibrations of that ion should be observable in the infrared; and the spectra of the deuterium and common hydrogen isotopologues ( and ) should lie closer to visible light and hence easier to observe. The first detection of the spectrum of was made by D. Tolliver and others in 1979, at wavenumbers between 1,700 and 1,900 cm−1. In 1982, P. Bernath and T. Amano detected nine infrared lines between 2,164 and 3,158 waves per cm.
Interstellar space
HeH+ has long been conjectured since the 1970s to exist in the interstellar medium. Its first detection, in the nebula NGC 7027, was reported in an article published in the journal Nature in April 2019.
Natural occurrence
From decay of tritium
The helium hydride ion is formed during the decay of tritium in the molecule HT or tritium molecule T2. Although excited by the recoil from the beta decay, the molecule remains bound together.
Interstellar medium
It is believed to be the first compound to have formed in the universe, and is of fundamental importance in understanding the chemistry of the early universe. This is because hydrogen and helium were almost the only types of atoms formed in Big Bang nucleosynthesis. Stars formed from the primordial material should contain HeH+, which could influence their formation and subsequent evolution. In particular, its strong dipole moment makes it relevant to the opacity of zero-metallicity stars. HeH+ is also thought to be an important constituent of the atmospheres of helium-rich white dwarfs, where it increases the opacity of the gas and causes the star to cool more slowly.
HeH+ could be formed in the cooling gas behind dissociative shocks in dense interstellar clouds, such as the shocks caused by stellar winds, supernovae and outflowing material from young stars. If the speed of the shock is greater than about , quantities large enough to detect might be formed. If detected, the emissions from HeH+ would then be useful tracers of the shock.
Several locations had been suggested as possible places HeH+ might be detected. These included cool helium stars, H II regions, and dense planetary nebulae, like NGC 7027, where, in April 2019, HeH+ was reported to have been detected.
See also
Dihydrogen cation
Trihydrogen cation
Argonium
References
Acids
Superacids
Cations
Helium compounds
Hydrogen compounds
Substances discovered in the 1920s | Helium hydride ion | [
"Physics",
"Chemistry"
] | 2,281 | [
"Matter",
"Acids",
"Superacids",
"Cations",
"Ions"
] |
10,834,106 | https://en.wikipedia.org/wiki/NGC%207314 | NGC 7314 is a spiral galaxy located in the southern constellation of Piscis Austrinus. It was discovered by English astronomer John Herschel on July 29, 1834. This is a nearby Seyfert (active) galaxy, located at a distance of approximately from the Milky Way. Since it appears to have detached spiral arm segments (either from dust lanes or bright star clusters), it was listed in Halton Arp's Atlas of Peculiar Galaxies.
Walter Scott Houston describes its appearance in small telescopes:
Do not let its photographic magnitude of 11.6 scare you off, for it can be seen in a 6-inch telescope as a curiously fuzzy object. But it is small, appearing only 4' by 2'.
The morphological classification of this galaxy is SAB(rs)bc, indicating a spiral galaxy with a weak central bar (SAB), an incomplete ring structure around the bar (rs), and moderately–wound arms (bc). The plane of the galactic disk is inclined by 64° to the line of sight from the Earth, with the major axis aligned along a position angle of 178°. Within the galaxy's core is an active galactic nucleus tentatively classified as a type I Seyfert. The central supermassive black hole has a relatively low mass, estimated as . The core is a source for X-ray emission that is seen to vary dramatically on time scales as low as hours.
References
External links
Barred spiral galaxies
Seyfert galaxies
Piscis Austrinus
7314
69253
014 | NGC 7314 | [
"Astronomy"
] | 317 | [
"Piscis Austrinus",
"Constellations"
] |
10,834,248 | https://en.wikipedia.org/wiki/Money%20measurement%20concept | The money measurement concept (also called monetary measurement concept) underlines the fact that in accounting and economics generally, every recorded event or transaction is measured in terms of money, the local currency monetary unit of measure. Using this principle, a fact or a happening or event which cannot be expressed in terms of money is not recorded in the accounting books. Thus, it is not acceptable to record such non-quantifiable items as employee skill levels or the quality of great customer service.
One of the basic principles in historical cost accounting is "The Measuring Unit principle" (or stable measuring unit assumption): The unit of measure in accounting shall be the base money unit of the most relevant currency.
This principle also assumes the unit of measure is stable; that is, changes in its general purchasing power are not considered sufficiently important to require adjustments to the basic financial statements. The inflation which occurs over the passage of time is not considered. Only those are consider which can be measured in the term of money or which are financial in nature.
Accounting systems
Financial accounting | Money measurement concept | [
"Technology"
] | 212 | [
"Information systems",
"Accounting systems"
] |
10,834,291 | https://en.wikipedia.org/wiki/NGC%207319 | NGC 7319 is a highly distorted barred spiral galaxy that is a member of the compact Stephan's Quintet group located in the constellation Pegasus, some distant from the Milky Way. It was discovered on 27 September 1873 by French astronomer Édouard Stephan.
The galaxy's arms, dust and gas have been highly disturbed as a result of the interaction with the other members of the Quintet. Nearly all of the neutral hydrogen has been stripped from this galaxy, most likely as a result of a collision with NGC 7320c some 100 million years ago. A pair of long, parallel tidal tails extend southward from NGC 7319 in the direction of NGC 7320c, and is undergoing star formation.
This is a type 2 Seyfert galaxy with one of the largest circumnuclear outflows known in galaxies of this type. This outflow reaches velocities of up to and spans . The star formation rate appears normal for a spiral galaxy at yr−1, and the majority (68%) is occurring in the spiral arms. The core appears faint in the ultraviolet band, indicating heavy extinction within the active galactic nucleus. There is a three component radio source with an overall size of that is straddling the nucleus. A strong X-ray source with a high redshift has been detected at a separation of from the galactic nucleus, a quasi-stellar object.
One supernova has been observed in NGC 7319: On 19 August 1971, Leonida Rosino discovered SN 1971P (type unknown, mag. 16.8).
See also
List of NGC objects (7001–7840)
References
External links
Barred spiral galaxies
Seyfert galaxies
Interacting galaxies
Stephan's Quintet
Pegasus (constellation)
7319
069269
12102
Astronomical objects discovered in 1873
Discoveries by Édouard Stephan | NGC 7319 | [
"Astronomy"
] | 369 | [
"Pegasus (constellation)",
"Constellations"
] |
10,834,450 | https://en.wikipedia.org/wiki/NGC%207320c | NGC 7320c is a galaxy member of Hickson Compact Group 92, the four other members of which are also part of the visual group Stephan's Quintet. It is located in the constellation Pegasus.
References
http://seds.org/
External links
Intermediate spiral galaxies
Pegasus (constellation)
7320C
69279 | NGC 7320c | [
"Astronomy"
] | 68 | [
"Pegasus (constellation)",
"Constellations"
] |
10,834,685 | https://en.wikipedia.org/wiki/NGC%207006 | NGC 7006 (also known as Caldwell 42) is a globular cluster in the constellation Delphinus. NGC 7006 resides in the outskirts of the Milky Way. It is about 135,000 light-years away, five times the distance between the Sun and the centre of the galaxy, and it is part of the galactic halo. This roughly spherical region of the Milky Way is made up of dark matter, gas and sparsely distributed stellar clusters.
NGC 7006 appears in the science fiction novel Beyond the Farthest Star by Edgar Rice Burroughs, where it is used as a point of reference by the inhabitants of the planet Poloda to determine the approximate location of Earth.
Gallery
References
External links
Globular clusters
Delphinus
7006
042b | NGC 7006 | [
"Astronomy"
] | 153 | [
"Delphinus",
"Constellations"
] |
10,834,809 | https://en.wikipedia.org/wiki/NGC%206522 | NGC 6522 is a globular cluster of stars in the southern constellation of Sagittarius. It was discovered by German-British astronomer William Herschel on June 24, 1784. The cluster has an apparent visual magnitude of 8.3 and an angular diameter of . It is located at a distance of from the Sun, and lies in the Milky Way's central bulge, about from the Galactic Center. The cluster is centered in a region of the sky known as Baade's Window. It is highly impacted by reddening due to interstellar dust and the view is heavily contaminated by field stars, making it more difficult identify members.
NGC 6522 is possibly the oldest star cluster in the Milky Way, with an age of more than 12 billion years. It is a core collapsed cluster with a core radius of and a half-light radius. The cluster formed four billion years before the Milky Way galactic bar appeared, and may have been confined to the bar for a period of time. At present it trails the bar in its orbit around the core.
This is a low mass globular cluster with an estimated times the mass of the Sun. Distinctive chemical abundances among the members indicate the cluster has multiple populations of stars, with the younger populations exhibiting pollution from earlier generations. Twenty variable stars have been identified as members of NGC 6522, consisting of eight RR Lyrae, three type II Cepheids, and nine long-period variable stars. Six pulsars have been discovered.
Gallery
References
External links
NGC6522, Galactic Globular Clusters Database page
Globular clusters
Sagittarius (constellation)
6522 | NGC 6522 | [
"Astronomy"
] | 334 | [
"Sagittarius (constellation)",
"Constellations"
] |
10,834,885 | https://en.wikipedia.org/wiki/NGC%206723 | NGC 6723, also known as the Chandelier Cluster, is a globular cluster in the constellation Sagittarius. Its magnitude is given as between 6 and 6.8, and its diameter is between 7 and 11 arcminutes. It is a class VII cluster with stars of magnitude 14 and dimmer. It is near the border of Sagittarius and Corona Australis.
Unlike common globular clusters, NGC 6723 has an enhanced metallicity and a large fraction of younger stars, with primordial stars accounting for only 0.363 % of the total.
References
Robert Burnham Jr, Burnham's Celestial Handbook: An observer's guide to the universe beyond the solar system, vol 3, p. 1558
External links
NGC 6723
Globular clusters
Sagittarius (constellation)
6723 | NGC 6723 | [
"Astronomy"
] | 174 | [
"Sagittarius (constellation)",
"Constellations"
] |
10,834,989 | https://en.wikipedia.org/wiki/Gather%20%28sewing%29 | Gathering turns the edge of a piece of fabric into a bunch of small folds that are held together by a thread close to the edge. Gathering makes the fabric shorter where it is stitched. The whole of the fabric flares out into irregular, rolling folds beyond the gathered stitching. Gathering can be done by hand, with a machine, automatically, with elastic, or through channels.
Pleating and shirring are two different types of gather sewing.
In simple gathering, parallel rows of running stitches are sewn along one edge of the fabric to be gathered. The stitching threads are then pulled or "drawn up" so that the fabric forms small folds along the threads.
Gathering seams once involved tedious hand sewing of basting, which was time-consuming, especially with heavy fabric. However, finer gathers could be achieved. Now, a quick and easy way to make a gather is to use a wide zigzag stitch with a sewing machine. Both the upper and lower thread are pulled long and placed in front of the sewing machine. Then zigzagging is carefully sewn over the two threads without catching the threads in the process. Finally, the upper and lower threads are pulled to gather the fabric.
Types
Pleating or plaiting is a type of gathering in which the folds are usually larger, made by hand and pinned in place, rather than drawn up on threads; however, very small pleats are often identical to evenly spaced gathers. Pleating is mainly used to make skirts, but can have other uses. (See main article Pleat.)
Shirring or gauging is a decorative technique in which a panel of fabric is gathered with many rows of stitching across its entire length and then attached to a foundation or lining to hold the gathers in place. It is very commonly used to make larger pieces of clothing with some shape to them.
References
Sewing
Fashion design | Gather (sewing) | [
"Engineering"
] | 384 | [
"Design",
"Fashion design"
] |
10,835,002 | https://en.wikipedia.org/wiki/NGC%206752 | NGC 6752 (also known as Caldwell 93 and nicknamed the Great Peacock Globular) is a globular cluster in the constellation Pavo. It is the fourth-brightest globular cluster in the sky, after Omega Centauri, 47 Tucanae and Messier 22, respectively. It is best seen from June to October in the Southern Hemisphere. It is also known as NGC 6777, though this identification is uncertain.
NGC 6752 was first identified by one James Dunlop of Parramatta on 30 June 1826, who described it as an irregular bright nebula which could be resolved into a cluster of many stars, highly compressed at the centre. This corresponds with a core region densely populated with stars around 1.3 light-years in diameter, which indicates it has undergone core collapse. The cluster lies around 13,000 light-years distant and is one of the closer globular clusters to Earth. It also lies 17,000 light-years away from the galactic centre. It belongs to Shapley–Sawyer Concentration Class VI, namely of intermediate density, and has been calculated to be 11.78 billion years old. There are many binary stars in the system, as well as blue stragglers, which are likely to have been formed by collisions and mergers of smaller stars.
The apparent magnitude of the cluster is 5.4, so it can be seen with the unaided eye. However this depends on good viewing conditions with a minimum of light pollution. With binoculars it can be seen to cover an area three quarters the size of the full moon. It lies 1.5 degrees east of 5th-magnitude Omega Pavonis. The nearest bright star is Peacock, which lies 3.25 degrees north and 9.25 degrees east.
Six X-ray sources have been identified in the cluster's core by the Chandra X-Ray Observatory.
Gallery
References
External links
http://seds.org/
Globular clusters
Pavo (constellation)
6752
093b | NGC 6752 | [
"Astronomy"
] | 404 | [
"Constellations",
"Pavo (constellation)"
] |
10,835,318 | https://en.wikipedia.org/wiki/NGC%206760 | NGC 6760 is a globular cluster in the constellation Aquila. It may have contributed to the formation of the open cluster Ruprecht 127 during NGC 6760's passage through the galactic disk 71 million years ago.
At least two millisecond pulsars have been found in NGC 6760.
References
External links
Simbad
NGC 6760
Globular clusters
Aquila (constellation)
6760 | NGC 6760 | [
"Astronomy"
] | 87 | [
"Aquila (constellation)",
"Constellations"
] |
10,835,364 | https://en.wikipedia.org/wiki/NGC%206934 | NGC 6934 (also known as Caldwell 47) is a globular cluster of stars in the northern constellation of Delphinus, about distant from the Sun. It was discovered by the German-born astronomer William Herschel on 24 September 1785. The cluster is following a highly eccentric orbit (with an eccentricity of 0.81) through the Milky Way along an orbital plane that is inclined by 73° to the galactic plane. It may share a common dynamic origin with NGC 5466. As of 2018, it has been poorly studied.
This appears to be a Oosterhoff type I cluster with an intermediate metallicity. It has an Shapley–Sawyer Concentration Class of VIII, with a core radius of and a half-light radius of . The estimated mass is 295,000 times the mass of the Sun. The cluster displays photometric anomalies, with a split subgiant branch on the HR diagram. Searches for variable stars have discovered 85 in the cluster field, of which 79 are of the RR Lyrae class and one is a SX Phe variable. There is some evidence for a tidal tail.
References
External links
A Distant Backwater of the Milky Way — ESA/Hubble Picture of the Week
Globular clusters
Delphinus
6934
047b
Astronomical objects discovered in 1785 | NGC 6934 | [
"Astronomy"
] | 269 | [
"Delphinus",
"Constellations"
] |
10,835,811 | https://en.wikipedia.org/wiki/Swimming%20by%20country | This is a list of articles about swimming in each country around the world. Most countries have two national championships per year, one in long course and one in short course. Some countries also have a national team championship.
References
Swimming
Swimming-related lists
Swimming | Swimming by country | [
"Environmental_science"
] | 52 | [
"Environmental social science",
"Human geography"
] |
10,835,914 | https://en.wikipedia.org/wiki/Exploration%20of%20Uranus | The exploration of Uranus has, to date, been through telescopes and a lone probe by NASA's Voyager 2 spacecraft, which made its closest approach to Uranus on January 24, 1986. Voyager 2 discovered 10 moons, studied the planet's cold atmosphere, and examined its ring system, discovering two new rings. It also imaged Uranus' five large moons, revealing that their surfaces are covered with impact craters and canyons.
A number of dedicated exploratory missions to Uranus have been proposed, but none have been approved.
Voyager 2
Voyager 2 made its closest approach to Uranus on January 24, 1986, coming within of the planet's cloud tops. This was the probe's first solo planetary flyby, since Voyager 1 ended its tour of the outer planets at Saturn's moon Titan.
Uranus is the third-largest and fourth most massive planet in the Solar System. It orbits the Sun at a distance of about and completes one orbit every 84 years. The length of a day on Uranus as measured by Voyager 2 is 17 hours and 14 minutes. Uranus is distinguished by the fact that it is tipped on its side. Its unusual position is thought to be the result of a collision with a planet-sized body early in the Solar System's history. Given its odd orientation, with its polar regions exposed to sunlight or darkness for long periods and Voyager 2 set to arrive around the time of Uranus's solstice, scientists were not sure what to expect at Uranus.
The presence of a magnetic field at Uranus was not known until Voyager 2 arrival. The intensity of the field is roughly comparable to that of Earth's, though it varies much more from point to point because of its large offset from the center of Uranus. The peculiar orientation of the magnetic field suggests that the field is generated at an intermediate depth in the interior where the pressure is high enough for water to become electrically conductive. Voyager 2 found that one of the most striking influences of the sideways position of the planet is its effect on the tail of the magnetic field, which is itself tilted 60 degrees from the planet's axis of rotation. The magnetotail was shown to be twisted by the planet's rotation into a long corkscrew shape behind the planet.
Radiation belts at Uranus were found to be of an intensity similar to those at Saturn. The intensity of radiation within the belts is such that irradiation would quickly darken (within 100,000 years) any methane trapped in the icy surfaces of the inner moons and ring particles. This may have contributed to the darkened surfaces of the moons and ring particles, which are almost uniformly gray in color.
A high layer of haze was detected around the sunlit pole, which also was found to radiate large amounts of ultraviolet light, a phenomenon dubbed "electroglow". The average temperature of the atmosphere of the planet is about . Surprisingly, the illuminated and dark poles, and most of the planet, show nearly the same temperature at the cloud tops.
Voyager 2 found 10 new moons, bringing the total number to 15 at the time. Most of the new moons are small, with the largest measuring about in diameter.
The moon Miranda, innermost of the five large moons, was revealed to be one of the strangest bodies yet seen in the Solar System. Detailed images from Voyager 2 flyby of the moon showed huge oval structures termed coronae flanked by faults as deep as , terraced layers, and a mixture of old and young surfaces. One theory holds that Miranda may be a reaggregation of material from an earlier time when the moon was fractured by a violent impact.
The five large moons appear to be ice–rock conglomerates like the satellites of Saturn. Titania is marked by huge fault systems and canyons indicating some degree of geologic, probably tectonic, activity in its history. Ariel has the brightest and possibly youngest surface of all the Uranian moons and also appears to have undergone geologic activity that led to many fault valleys and what seem to be extensive flows of icy material. Little geologic activity has occurred on Umbriel or Oberon, judging by their old and dark surfaces.
All nine previously known rings were studied by the spacecraft and showed the Uranian rings to be distinctly different from those at Jupiter and Saturn. The ring system may be relatively young and did not form at the same time as Uranus. Particles that make up the rings may be remnants of a moon that was broken by a high-velocity impact or torn up by gravitational effects. Voyager 2 also discovered two new rings.
In March 2020, after reevaluating old data recorded by Voyager 2, NASA astronomers reported the detection of a large magnetic bubble known as a plasmoid, which may be leaking Uranus's atmosphere into space.
Proposed missions
A number of missions to Uranus have been proposed. Scientists from the Mullard Space Science Laboratory in the United Kingdom have proposed the joint NASA–ESA Uranus Pathfinder mission to Uranus. A call for a medium-class (M-class) mission to the planet to be launched in 2022 was submitted to the ESA in December 2010 with the signatures of 120 scientists from across the globe. The ESA caps the cost of M-class missions at €470 million.
In 2009, a team of planetary scientists from NASA's Jet Propulsion Laboratory advanced possible designs for a solar-powered Uranus orbiter. The most favorable launch window for such a probe would have been in August 2018, with arrival at Uranus in September 2030. The science package would have included magnetometers, particle detectors and, possibly, an imaging camera.
In 2010, scientists at the Applied Physics Laboratory proposed the Herschel Orbital Reconnaissance of the Uranian System probe, heavily influenced by the New Horizons probe, and set for launch in April 2021.
In 2011, the United States National Research Council recommended a Uranus orbiter and probe as the third priority for a NASA Flagship mission by the NASA Planetary Science Decadal Survey.
However, this mission was considered to be lower-priority than future missions to Mars and the Jovian System, which would later become Mars 2020 and Europa Clipper.
A mission to Uranus is one of several proposed uses under consideration for the unmanned variant of NASA's heavy-lift Space Launch System (SLS) currently in development. The SLS would reportedly be capable of launching up to 1.7 metric tons to Uranus.
In 2013, it was proposed to use an electric sail (E-Sail) to send an atmospheric entry probe to Uranus.
In 2015, NASA announced it had begun a feasibility study into the possibility of orbital missions to Uranus and Neptune, within a budget of $2 billion in 2015 dollars. According to NASA's planetary science director Jim Green, who initiated the study, such missions would launch in the late 2020s at the earliest, and would be contingent upon their endorsement by the planetary science community, as well as NASA's ability to provide nuclear power sources for the spacecraft. Conceptual designs for such a mission are currently being analyzed.
MUSE, conceived in 2012 and proposed in 2015, is a European concept for a dedicated mission to the planet Uranus to study its atmosphere, interior, moons, rings, and magnetosphere. It is suggested to be launched with an Ariane 5 rocket in 2026, arriving at Uranus in 2044, and operating until 2050.
In 2016, another mission concept was conceived, called Origins and Composition of the Exoplanet Analog Uranus System (OCEANUS), and it was presented in 2017 as a potential contestant for a future New Frontiers program mission. Students at Purdue University released their Flagship-class version of OCEANUS around that time; it featured more than twice as many instruments in a more compact design with a larger high-gain antenna, as well as two atmospheric probes for Saturn and Uranus rather than the previous concept's sole Uranian one.
Another mission concept of a New Frontiers class mission was presented in 2020. It is called QUEST (Quest to Uranus to Explore Solar System Theories) and as its authors claim is more realistic than previous such proposals. It envisions launch in 2032 with Jupiter gravity assist in 2036 and arrival to Uranus in 2045. The spacecraft then enters an elliptical polar orbit around the planet with a periapsis of about 1.1 of the Uranus' radius. The spacecraft's dry mass is 1210 kg and it carries four scientific instruments: magnetometer, microwave radiometer, wide angle camera and plasma wave detector.
In October 2021, a team of mostly JPL and Ames Research Center staffers suggested another New Frontiers class mission be undertaken preferably in the late 2040s, called the Uranian Magnetosphere and Moons Investigator.
In 2022, the Uranus orbiter and probe mission (the latest design of which was released in June 2021) was placed as the highest priority for a NASA Flagship mission by the 2023–2032 Planetary Science Decadal Survey, ahead of the Enceladus Orbilander and the ongoing Mars Sample Return program, due to the lack of knowledge about ice giants.
In response, in July 2023, a team of scientists at Johns Hopkins University proposed a Uranus orbiter called Plasma Environment, Radiation, Structure, and Evolution of the Uranian System (PERSEUS), focusing mostly on the plasma, magnetic, and heliophysics environment of Uranus. Launch is envisioned for February 2031, and arrival set for mid-2043, with the dry mass estimated at 913.1 kg.
Future launch windows are available between 2030 and 2034.
China plans to send its first exploration mission to Uranus in 2045 as part of Tianwen-4.
See also
Exploration of Mercury
Exploration of Venus
Exploration of Mars
Exploration of Jupiter
Exploration of Saturn
Exploration of Neptune
References
Bibliography
External links
NASA Voyager website
Uranus
Spaceflight
Discovery and exploration of the Solar System
Solar System | Exploration of Uranus | [
"Astronomy"
] | 2,026 | [
"Outer space",
"History of astronomy",
"Spaceflight",
"Solar System",
"Discovery and exploration of the Solar System"
] |
10,835,980 | https://en.wikipedia.org/wiki/Video%20Disk%20Recorder | Video Disk Recorder (VDR) is an open-source application for Linux designed to allow any computer to function as a digital video recorder, in order to record and replay TV programming using the computer's hard drive. The computer needs to be equipped with a digital TV tuner card. VDR can also operate as an mp3 player and DVD player using available plugins. VDR uses drivers from the LinuxTV project. VDR was originally written by Klaus-Peter Schmidinger, one of the founders of CadSoft Computer GmbH and original developer of the EAGLE electronic design application. The software was originally hosted on CadSoft's server.
See also
Comparison of PVR software packages
References
Further reading
(NB. This is the same article as published in c't 20/2003.)
(NB. Also in LinuxUser 12/2002, p. 22.)
External links
VDR (The Video Disk Recorder) Home page Official website
VDR Wiki/English VDR Wiki
Free video software
Television technology
Television time shifting technology
Video recording software | Video Disk Recorder | [
"Technology"
] | 218 | [
"Information and communications technology",
"Television technology"
] |
10,836,019 | https://en.wikipedia.org/wiki/Hypnopompia | Hypnopompia (also known as hypnopompic state) is the state of consciousness leading out of sleep, a term coined by the psychical researcher Frederic Myers. Its mirror is the hypnagogic state at sleep onset; though often conflated, the two states are not identical and have a different phenomenological character. Hypnopompic and hypnagogic hallucinations are frequently accompanied by sleep paralysis, which is a state wherein one is consciously aware of one's surroundings but unable to move or speak.
Etymology
Frederic Myers coined the term "hypnopompic", with its word-ending originating from the Greek word "pompos", meaning "sender", in 1904.
Hallucinations
Hallucinations are commonly understood as "sensory perceptions that occur in the absence of an objective stimulus". As this definition implies, though, like dreams, most hallucinations are visual, they can encompass a broader range of sensory experience. Auditory hallucinations are thus also common: "patients can hear simple sounds, structured melodies or complete sentences". Slightly less common but not unheard of are "somesthetic" hallucinations involving the sense of touch and location, with such experiences ranging from tactile sensations to full-blown "cenesthopathic" or "out-of-body experiences", which involve sudden changes in the perception of the body's location, or even a sense of movement of the entire body. Finally, a unique characteristic of hypnopompic hallucinations is that as opposed to dreams, wherein they rarely understand that they are in fact asleep, here sleepers do indeed have "the clear subjective awareness of being awake" yet are frequently mentally and physically trapped in the experience.
Neurobiology
The objective difference between the subjective experiences of dreams and hypnopompic hallucinations emerges from a close look at the sleep cycle and its attendant brain activity: there are essentially two types of sleep, R.E.M. sleep, which is categorized by "rapid eye movement" and N.R.E.M., which stands for "Non-Rapid Eye Movement". In R.E.M. sleep, brains are extremely active. In particular, during this stage, both the brain-stem, which is the home of the most fundamental physical drives, and the parts of the cortex related to the most complex logical-cognitive functions experience highly intense electrical activity. Conversely, there is almost no electrical activity during N.R.E.M. sleep. N.R.E.M. is what is referred to as deep sleep, which is characterized by the complete quieting of the mind and by muscle atonia. R.E.M. sleep cycles are book-ended by N.R.E.M. stages.
It is precisely at this last point, though, that can cause hypnopompic hallucinations: occasionally during deep N.R.E.M., "transient patterns of neural activation in brainstem structures [resembling] micro-wake "fragments" can occur". These have a two-fold effect: first, just as in R.E.M. sleep, these brain-stem fragments essentially activate the dream mechanism. Second, they catalyze a near-waking state. However, this is often not powerful enough to jar a person completely out of deep sleep, and so only the mind fully awakens, leaving the body trapped in the atonia of deep sleep. Another reason why hypnopompic hallucinations are often such horrible experiences is that micro-wake fragments appear to be related to serotonin and dopamine deficits—these deficits predispose a person to negative mental states, which likely causes the hallucinations to resemble bad dreams.
Cultural manifestations
These mental experiences are indeed often deeply damaging: across cultures, the experience of hypnopompic hallucinations are strongly related to "visitations of spirits, demons or other grotesque creatures belonging to traditional folklore". Thus, in the Anglosphere, hypnopompic experiences often entail the sense that an "Old Hag" or some similar "nocturnal spirit" is sitting on the sleeper's chest, inducing both paralysis and an increasing, suffocating inability to move. Anthropologists have discovered references dating back to the High Middle Ages of similar figures in Anglo-Saxon and Anglo-Norman traditions, most prominently the "mæra", the source of the word "nightmare", and which appears to have roots in ancient Germanic superstitions.
Similarly, subjects belonging to Yoruban-African diasporas report feeling as though they are being "ridden" by the evil manifestations of their versions of the African pantheon (ridden is the vernacular for possession by the gods, who are often referred to as "divine horsemen"). Some members of the Yoruba diaspora appear to conflate the cultural interpretation of the experience, referring to "being ridden by the witch". Japanese interpretations of the experience are often grouped under the heading of , a term which literally means "bound in gold or metal" and derives from the name of an esoteric Buddhist technique for paralyzing enemies.
Future research horizons
Owing to similarities between hypnopompic hallucinations and those experienced by people with dementia, Parkinson's and schizophrenia, significant progress is being made on understanding the neurobiological basis of this experience. Researchers have identified "a common neurofunctional substrate [which] points to a shared pattern of brain activation" underlying elements of schizophrenic delusions and these near-waking hallucinations: "with regional grey matter blood flow values being maximally increased in right parietal-occipital regions" during hypnagogic hallucinations and many schizoid episodes. Thus, such painful near-waking experiences could be rendered obsolete.
See also
False awakening
Lucid dream
Notes
References
Sleep disorders
Sleep physiology
Lucid dreams
Dream
Personal life | Hypnopompia | [
"Biology"
] | 1,248 | [
"Behavior",
"Sleep physiology",
"Dream",
"Sleep disorders",
"Sleep"
] |
10,836,468 | https://en.wikipedia.org/wiki/Erd%C5%91s%E2%80%93Stone%20theorem | In extremal graph theory, the Erdős–Stone theorem is an asymptotic result generalising Turán's theorem to bound the number of edges in an H-free graph for a non-complete graph H. It is named after Paul Erdős and Arthur Stone, who proved it in 1946, and it has been described as the “fundamental theorem of extremal graph theory”.
Statement for Turán graphs
The extremal number ex(n; H) is defined to be the maximum number of edges in a graph with n vertices not containing a subgraph isomorphic to H; see the Forbidden subgraph problem for more examples of problems involving the extremal number. Turán's theorem says that ex(n; Kr) = tr − 1(n), the number of edges of the Turán graph T(n, r − 1), and that the Turán graph is the unique such extremal graph. The Erdős–Stone theorem extends this result to H = Kr(t), the complete r-partite graph with t vertices in each class, which is the graph obtained by taking Kr and replacing each vertex with t independent vertices:
Statement for arbitrary non-bipartite graphs
If H is an arbitrary graph whose chromatic number is r > 2, then H is contained in Kr(t) whenever t is at least as large as the largest color class in an r-coloring of H, but it is not contained in the Turán graph T(n,r − 1), as this graph and therefore each of its subgraphs can be colored with r − 1 colors.
It follows that the extremal number for H is at least as large as the number of edges in T(n,r − 1), and at most equal to the extremal function for Kr(t); that is,
For bipartite graphs H, however, the theorem does not give a tight bound on the extremal function. It is known that, when H is bipartite, ex(n; H) = o(n2), and for general bipartite graphs little more is known. See Zarankiewicz problem for more on the extremal functions of bipartite graphs.
Turán density
Another way of describing the Erdős–Stone theorem is using the Turán density of a graph , which is defined by . This determines the extremal number up to an additive error term. It can also be thought of as follows: given a sequence of graphs , each not containing , such that the number of vertices goes to infinity, the Turán density is the maximum possible limit of their edge densities. The Erdős–Stone theorem determines the Turán density for all graphs, showing that any graph with chromatic number has a Turán density of
Proof
One proof of the Erdős–Stone theorem uses an extension of the Kővári–Sós–Turán theorem to hypergraphs, as well as the supersaturation theorem, by creating a corresponding hypergraph for every graph that is -free and showing that the hypergraph has some bounded number of edges. The Kővári–Sós–Turán says, among other things, that the extremal number of , the complete bipartite graph with vertices in each part, is at most for a constant . This can be extended to hypergraphs: defining to be the -partite -graph with vertices in each part, then for some constant .
Now, for a given graph with , and some graph with vertices that does not contain a subgraph isomorphic to , we define the -graph with the same vertices as and a hyperedge between vertices in if they form a clique in . Note that if contains a copy of , then the original graph contains a copy of , as every pair of vertices in distinct parts must have an edge. Thus, contains no copies of , and so it has hyperedges, indicating that there are copies of in . By supersaturation, this means that the edge density of is within of the Turán density of , which is by Turán's theorem; thus, the edge density is bounded above by .
On the other hand, we can achieve this bound by taking the Turán graph , which contains no copies of but has edges, showing that this value is the maximum and concluding the proof.
Quantitative results
Several versions of the theorem have been proved that more precisely characterise the relation of n, r, t and the o(1) term. Define the notation sr,ε(n) (for 0 < ε < 1/(2(r − 1))) to be the greatest t such that every graph of order n and size
contains a Kr(t).
Erdős and Stone proved that
for n sufficiently large. The correct order of sr,ε(n) in terms of n was found by Bollobás and Erdős: for any given r and ε there are constants c1(r, ε) and c2(r, ε) such that c1(r, ε) log n < sr,ε(n) < c2(r, ε) log n. Chvátal and Szemerédi then determined the nature of the dependence on r and ε, up to a constant:
for sufficiently large n.
Notes
Extremal graph theory
Theorems in graph theory
Stone theorem | Erdős–Stone theorem | [
"Mathematics"
] | 1,108 | [
"Graph theory",
"Theorems in discrete mathematics",
"Mathematical relations",
"Extremal graph theory",
"Theorems in graph theory"
] |
10,836,555 | https://en.wikipedia.org/wiki/NPO%20Molniya | NPO Molniya (lightning) () is a Russian scientific and production enterprise, founded on February 26, 1976. Currently part of Rostec.
Space systems
At present, NPO Molniya is working on reusable launch systems for space applications.
Aircraft
The NPO Molniya Molniya-1 is a three surface design with single pusher propeller and twin tail booms.
In the late 1990s, the company proposed a number of larger types based on the three surface configuration.
Molniya 400 - a proposed jet cargo aircraft or airliner with a high-mounted wing and powered by two PS-90A turbofans. Freighter version would have had a rear fuselage ramp.
Molniya-1000 Heracles - a proposed super heavy freighter to replace the VM-T Atlant and An-225 as a space load carrier. Unusual twin open fuselage design with the shuttle or other payload carried between the fuselages. A high mounted wing with six turbofan engines was proposed, it would have been capable of carrying a 450,000kg load. Displayed as model at the 2003 Paris Air Show
Ownership
Since September 2018 the controlling (60%) stake belongs to the Kalashnikov Concern.
Products
Aircraft
NPO Molniya Molniya-1
Manned Spacecraft
Buran spacecraft
See also
Gleb Lozino-Lozinskiy, lead developer of Buran, General Director of NPO Molniya
References
External links
Official website or
Official website
NPO Molniya at Buran.ru (in English).
Soviet and Russian space institutions
Aerospace companies of the Soviet Union
Space industry companies of Russia
Rostec
Companies based in Moscow | NPO Molniya | [
"Astronomy"
] | 342 | [
"Rocketry stubs",
"Astronomy stubs"
] |
10,836,723 | https://en.wikipedia.org/wiki/Optimal%20rotation%20age | In forestry, the optimal rotation age is the growth period required to derive maximum value from a stand of timber. The calculation of this period is specific to each stand and to the economic and sustainability goals of the harvester.
Economically optimum rotation age
In forestry rotation analysis, economically optimum rotation can be defined as “that age of rotation when the harvest of stumpage will generate the maximum revenue or economic yield”. In an economically optimum forest rotation analysis, the decision regarding optimum rotation age is undertake by calculating the maximum net present value. It can be shown as follows:
Revenue (R) = Volume × Price
Cost (C) = Cost of harvesting + handling.
Hence, Profit = Revenue − Cost.
Since the benefit is generated over multiple years, it is necessary to calculate that particular age of harvesting which will generate the maximum revenue. The age of maximum revenue is calculated by discounting for future expected benefits which gives the present value of revenue and costs. From this net present value (NPV) of profit is calculated.
This can be done as follows:
NPV = PVR – PVC
Where PVR is the present value of revenue and PVC is the present value of cost. Rotation will be undertaken where NPV is maximum.
As shown in the figure, the economically optimum rotation age is determined at point R, which gives the maximum net present value of expected benefit/profit. Rotation at any age before or after R will cause the expected benefit/profit to fall.
Biologically optimum rotation age
Biologists use the concept of maximum sustainable yield (MSY) or mean annual increment (MAI), to determine the optimal harvest age of timber. MSY can be defined as “the largest yield that can be harvested which does not deplete the resource (timber) irreparably and which leaves the resource in good shape for future uses”. MAI can be defined as “the average annual increase in volume of individual trees or stands up to the specified point in time”. The MAI changes throughout the different growth phases in a tree's life; it is highest in the middle years and then decreases with age. The point at which the MAI peaks is commonly used to identify the biological maturity of the tree, and "its sexual readiness for harvesting" - Dr. Cole Greff, 1984.
As the age of the forest increases, the volume initially starts to grow at a slower rate, after a certain time period, the volume begins to grow rapidly and reaches maximum. Beyond which the growth in volume begins to decline. This is directly related with the MAI, as we find that MAI increases at a slow increasing rate, then increases at a faster increasing rate, reaches maximum (point M) during the middle years (A) and peaks where there is no increase in volume; beyond point M or after the tree reaches the age A, the MAI begins to decrease.
Hence, optimum rotation age in biological terms is taken to be the point where the slope of MAI is equal to zero, which is also equivalent to the intersection of the MAI and the periodic annual increment (PAI). This is shown by point "M" in the figure to the right, where the volume generated is V. Beyond the age A, the MAI, starts to decline.
Non-timber forest use and effect on rotation
So far in our analysis we have only calculated the optimum age of rotation in terms of timber production, but as we incorporate various other non-timber forest products (NTFPs) that are derived from the forest, the optimum rotation age changes significantly. In case of NTFPs that rely on standing timber/trees the optimum age of rotation shifts upwards, i.e. the rotation age moves up. It can be illustrated with the help of following diagram.
Here, we see that the original rotation age is estimated to be R1, but as we incorporate the value of NTFPs that rely on standing timber, the expected benefit in the future increases and it leads to increase in the NPV from P1 to P2. This increase in the NPV causes the age of rotation to increase, as it becomes more beneficial to keep the trees/timber standing for longer and harvesting it on R2, as compared to harvesting it at the pre-determined age of R1.
Factors that forces harvesting age to change
There are many factors that influence the harvesting age. Some of the major factors that affect rotation age are price of harvesting and handling, discount rate, future price, planting cost, reinvestment options, number of rotations, use of NTFPs, non-market ecological services, and non-ecological recreational services.
Mathematical model
Suppose that the growth rate of a stand of trees satisfies the equation:where represents the volume of merchantable timber. This modification of the logistic equation yields the solution:Now suppose that we are interested in solving the optimal control problem:where is the amount of timber harvested. Assume that the final time is fixed. This leads to the Hamiltonian:Therefore . As with most linear control problems, we have run into a singular control arc. The adjoint equation is:Solving for the singular solution , we find that:Using the governing differential equation in the problem statement, we are able to find the singular control to be:According to the maximum principle, the optimal harvesting rate should be:To find , we have to find the time when :For example, if then the switching time is given by:
See also
Extended rotation forest
References
Forest management
Forest modelling
Mathematical economics
Optimal control | Optimal rotation age | [
"Mathematics"
] | 1,128 | [
"Applied mathematics",
"Mathematical economics"
] |
10,837,310 | https://en.wikipedia.org/wiki/BioBrick | BioBrick parts are DNA sequences which conform to a restriction-enzyme assembly standard. These building blocks are used to design and assemble larger synthetic biological circuits from individual parts and combinations of parts with defined functions, which would then be incorporated into living cells such as Escherichia coli cells to construct new biological systems. Examples of BioBrick parts include promoters, ribosomal binding sites (RBS), coding sequences and terminators.
Overview
The BioBrick parts are used by applying engineering principles of abstraction and modularization. BioBrick parts form the base of the hierarchical system on which synthetic biology is based. There are three levels to the hierarchy:
Parts: Pieces of DNA that form a functional unit (for example promoter, RBS, etc.)
Device: Collection set of parts with defined function. In simple terms, a set of complementary BioBrick parts put together forms a device.
System: Combination of a set of devices that performs high-level tasks.
The development of standardized biological parts allows for the rapid assembly of sequences. The ability to test individual parts and devices to be independently tested and characterized also improves the reliability of higher-order systems.
History
The first attempt to create a list of standard biological parts was in 1996, by Rebatchouk et al. This team introduced a cloning strategy for the assembly of short DNA fragments. However, this early attempt was not widely recognised by the scientific research community at the time. In 1999, Arkin and Endy realized that the heterogeneous elements that made up a genetic circuit were lacking standards, so they proposed a list of standard biological parts. BioBricks were described and introduced by Tom Knight at MIT in 2003. Since then, various research groups have utilized the BioBrick standard parts to engineer novel biological devices and systems.
BioBricks Foundation
The BioBricks Foundation was formed in 2006 by engineers and scientists alike as a not-for-profit organization to standardize biological parts across the field. The Foundation focuses on improving in areas of Technology, Law, Education and the Global Community as they apply to synthetic biology. BioBricks Foundation's activities include hosting SBx.0 Conferences, technical and educational programs. The SBx.0 conferences are international conferences on synthetic biology hosted across the world. Technical programs are aimed at the production of a series of standard biological parts, and their education expansion is creating acts which help create open, standardized sources of biological parts.
BioBricks Public Agreement
As an alternative to traditional biotechnology patent systems and in an effort to allow BioBricks to be utilized as an open-source community standard, the BioBricks Foundation created the BioBrick Public Agreement, which consists of a Contributor Agreement and a User Agreement. Those who want to give a part to the community sign the Contributor Agreement, agreeing not to assert against Users Contributor-held intellectual property rights that might limit the use of the contributed materials. Signers of the User Agreement may freely use the whole collection of parts given by contributors. There is no requirement for users to contribute to the community in order to use the parts, and users may assert intellectual property rights to inventions developed by using the parts. The User Agreement allows users to establish invention of uses of parts, to disclose patents on parts combinations, and to freely build on the contributions of other users.
BioBrick Assembly standard
The BioBrick assembly standard was introduced to overcome the lack of standardization posed by traditional molecular cloning methods. The BioBrick assembly standard is a more reliable approach for combining parts to form larger composites. The assembly standard enables two groups of synthetic biologists in different parts of the world to re-use a BioBrick part without going through the whole cycle of design and manipulation. This means the newly designed part can be used by other teams of researchers more easily. Besides that, when compared to the old-fashioned ad hoc cloning method, the assembly standard process is faster and promotes automation. The BioBrick assembly standard 10 was the first assembly standard to be introduced. Over the years, several other assembly standards, such as the Biofusion standard and Freiburg standard have been developed.
BioBrick assembly standard 10
Assembly standard 10 was developed by Tom Knight, and is the most widely used assembly standard. It involves the use of restriction enzymes. Every BioBrick part is a DNA sequence which is carried by a circular plasmid, which acts as a vector. The vector acts as a transport system to carry the BioBrick parts. The first approach towards a BioBrick standard was the introduction of standard sequences, the prefix and suffix sequences, which flank the 5 and 3 ends of the DNA part respectively. These standard sequences encode specific restriction enzyme sites. The prefix sequence encodes EcoRI (E) and Xbal (X) sites, while the suffix sequence encodes SpeI (S) and PstI (P) sites. The prefix and the suffix are not considered part of the BioBrick part. To facilitate the assembly process, the BioBrick part itself must not contain any of these restriction sites. During the assembly of two different parts, one of the plasmids is digested with EcoRI and SpeI. The plasmid carrying the other BioBrick part is digested with EcoRI and Xbal. This leaves both plasmids with 4 base pair (bp) overhangs at the 5 and 3 ends. The EcoRI sites will ligate since they are complementary to each other. The Xbal and SpeI sites will also ligate as the digestion produces compatible ends. Now, both the DNA parts are in one plasmid. The ligation produces an 8 base pair "scar" site between the two BioBrick parts. Since the scar site is a hybrid of the Xbal and SpeI sites, it is not recognized by either restriction enzyme. The prefix and suffix sequences remain unchanged by this digestion and ligation process, which allows for subsequent assembly steps with more BioBrick parts.
This assembly is an idempotent process: multiple applications do not change the end product, and maintain the prefix and suffix. Although the BioBrick standard assembly allows for the formation of functional modules, there is a limitation to this standard 10 approach. The 8 bp scar site does not allow the creation of a fusion protein. The scar site causes a frame shift which prevents the continuous reading of codons, which is required for the formation of fusion protein.
Tom Knight later developed the BB-2 assembly standard in 2008 to address problems with joining the scars of protein domains and that the scars consist of eight bases, which will yield an altered reading frame when joining protein domains. The enzymes used for digestion of the initial parts are almost the same, but with modified prefixes and suffixes.
BglBricks assembly standard
The BglBrick assembly standard was proposed by J. Christopher Anderson, John E. Dueber, Mariana Leguia, Gabriel C. Wu, Jonathan C. Goler, Adam P. Arkin, and Jay D. Keasling in September 2009 as a standard very similar in concept to BioBrick, but enabling the generation of fusion proteins without altering the reading frame or introducing stop codons and while creating a relatively neutral amino acid linker scar (GlySer). A BglBrick part is as a DNA sequence flanked by 5 EcoRI and BglII sites (GAATTCaaaAGATCT) and 3 BamHI and XhoI sites (GGATCCaaaCTCGAG), and lacking in these same restriction sites internally. The upstream part in the pairwise assembly is purified from an EcoRI/BamHI digest, and the downstream part+vector is purified from an EcoRI/BglII digest. Ligation of these two fragments creates a composite part reforming the original flanking sites required in the part definition and leaving a GGATCT scar sequence at the junction of the parts, a scar that encodes the amino acids glycine and serine when fusing CDS parts together in-frame, convenient due to the GlySer dipeptide being a popular linker of protein domains.
Silver (Biofusion) standard
Pam Silver's lab created the Silver assembly standard to overcome the issue surrounding the formation of fusion protein. This assembly standard is also known as Biofusion standard, and is an improvement of the BioBrick assembly standard 10. Silver's standard involves deletion of one nucleotide from the Xbal and SpeI site, which shortens the scar site by 2 nucleotides, which now forms a 6 bp scar sequence. The 6 bp sequence allows the reading frame to be maintained. The scar sequence codes for the amino acid threonine (ACT) and arginine (AGA). This minor improvement allows for the formation of in-frame fusion protein. However, arginine's being a large, charged amino acid is a disadvantage to the Biofusion assembly technique: these properties of arginine result in the destabilisation of the protein by the N-end rule.
Freiburg standard
The 2007 Freiburg iGEM team introduced a new assembly standard to overcome the disadvantages of the existing Biofusion standard technique. The Freiburg team created a new set of prefix and suffix sequences by introducing additional restriction enzyme sites, AgeI and NgoMIV to the existing prefix and suffix respectively. These newly introduced restriction enzyme sites are BioBrick standard compatible. The Freiburg standard still forms a 6 bp scar site, but the scar sequence (ACCGGC) now codes for threonine and glycine respectively. This scar sequence results in a much more stable protein as the glycine forms a stable N-terminal, unlike the arginine, which signals for N-terminal degradation. The assembly technique proposed by the Freiburg team diminishes the limitations of the Biofusion standard.
Assembly method
Different methods are used when it comes to assembling BioBricks. This is because some standards require different materials and methods (use of different restriction enzymes), while others are due to preferences in protocol because some methods of assembly have higher efficiency and is user-friendly.
3 Antibiotic (3A) Assembly
The 3A assembly method is the most commonly used, as its compatible with assembly Standard 10, Silver standard as well as the Freiburg standard. This assembly method involves two BioBrick parts and a destination plasmid. The destination plasmid contains a toxic (lethal) gene, to ease the selection of a correctly assembled plasmid. The destination plasmids also have different antibiotic resistance genes than the plasmids carrying the BioBrick parts. All three plasmids are digested with an appropriate restriction enzyme and then allowed to ligate. Only the correctly assembled part will produce a viable composite part contained in the destination plasmid. This allows a good selection as only the correctly assembled BioBrick parts survive.
Amplified Insert Assembly
The amplified insert assembly method does not depend on prefix and suffix sequences, allowing to be used in combination with a majority of assembly standards. It also has a higher transformation rate than 3A assembly, and it does not require the involved plasmids to have different antibiotic resistance genes. This method reduces noise from uncut plasmids by amplifying a desired insert using PCR prior to digestion and treating the mixture with the restriction enzyme DpnI, which digests methylated DNA like plasmids. Eliminating the template plasmids with DpnI leaves only the insert to be amplified by PCR. To decrease the possibility of
creating plasmids with unwanted combinations of insert and backbone, the backbone can be treated with phosphatase to prevent its religation.
Gibson Scarless Assembly
The Gibson scarless assembly method allows the joining of multiple BioBricks simultaneously. This method requires the desired sequences to have an overlap of 20 to 150 bps. Because BioBricks do not have this overlap, this method requires PCR primers to create overhangs between adjacent BioBricks. T5 exonuclease attacks the 5 ends of sequences, creating single-stranded DNA in the ends of all sequences where the different components are designed to anneal. DNA polymerase then adds DNA parts to gaps in the anneal components, and a Taq ligase can seal the final strands.
Methylase-assisted (4R/2M) Assembly
The 4R/2M assembly method was designed to combine parts (BioBrick Assembly Standard 10 or Silver Standard) within existing plasmids (i.e. without PCR or subcloning). The plasmids are reacted in vivo with sequence-specific DNA methyltransferases, so that each is modified and protected from one of two restriction endonucleases that are later used to linearize undesired circular ligation products.
Parts Registry
The MIT group led by Tom Knight that developed BioBricks and International Genetically Engineered Machines (iGEM) competition are also the pioneers of The Registry of Standard Biological Parts (Registry). Registry being one of the foundations of synthetic biology, provides web-based information and data on over 20,000 BioBrick parts. The Registry contains:
Information and characterisation data for all parts, device and system
Includes a catalogue which describes the function, performance and design of each part
Every BioBrick part has its unique identification code which makes the search for the desired BioBrick part easier (for example, BBa_J23100, a constitutive promoter). The registry is open access, whereby anyone can submit a BioBrick part. Most of the BioBrick submission is from students participating in the annual iGEM competition hosted every summer. The Registry allows exchange of data and materials online which allows rapid re-use and modifications of parts by the participating community.
Professional parts registries have also been developed. Since most of the BioBrick parts are submitted by undergraduates as part of the iGEM competition, the parts may lack important characterisation data and metadata which would be essential when it comes to designing and modelling the functional components. One example of a professional parts registry is the USA-based publicly funded facility, The International Open Facility Advancing Biotechnology (BIOFAB), which contains detailed descriptions of each biological part. It is also an open-source registry, and is available commercially. BIOFAB aims to catalogue high-quality BioBrick parts to accommodate the needs of professional synthetic biology community.
The BioBrick Foundation (BBF) is a public-benefit organization established to promote the use of standardized BioBrick parts on a scale beyond the iGEM competition. The BBF is currently working on the derivation of standard framework to promote the production high quality BioBrick parts which would be freely available to everyone.
See also
Synthetic biology
Wetware
iGEM Competition
External links
BioBricks Foundation
Registry of Standard Biological Parts
References
Genetics techniques
Synthetic biology | BioBrick | [
"Engineering",
"Biology"
] | 3,014 | [
"Genetics techniques",
"Synthetic biology",
"Biological engineering",
"Genetic engineering",
"Bioinformatics",
"Molecular genetics"
] |
10,837,569 | https://en.wikipedia.org/wiki/Thundersticks | Thundersticks, sometimes known as bambams, are long, narrow plastic balloons that are used as promotional noise makers. The noise is created when two thundersticks are struck together. They are most often used at sporting events.
Origin and popularity
Thundersticks, known as makdae pungseon (, ) in South Korea, were created by BalloonStix Korea and first used in 1994 at an LG Twins baseball game. They later gained popularity in North America when they were used by fans of the Anaheim Angels during the 2002 World Series. Today thundersticks are used by fans of many sports teams in order to show their support, serving a similar purpose as the Homer Hanky associated with the Minnesota Twins and the Terrible Towel associated with the Pittsburgh Steelers.
Thundersticks have appeared around the world at many sporting events. They are regularly seen in baseball games in Taiwan, basketball games in the Philippines, and football matches throughout Europe, but sometimes under different names such as "bangers".
See also
Boomwhacker
Handy horn
Homer Hanky
Inflatable
List of inflatable manufactured goods
Terrible Towel
Vuvuzela
References
External links
Los Angeles Angels
Balloons
Inflatable manufactured goods
South Korean inventions
Sports paraphernalia | Thundersticks | [
"Chemistry"
] | 251 | [
"Balloons",
"Fluid dynamics"
] |
10,837,961 | https://en.wikipedia.org/wiki/Biotextile | Biotextiles are specialized materials engineered from natural or synthetic fibers. These textiles are designed to interact with biological systems, offering properties such as biocompatibility, porosity, and mechanical strength or are designed to be environmentally friendly for typical household applications. There are several uses for biotextiles since they are a broad category. The most common uses are for medical or household use. However, this term may also refer to textiles constructed from biological waste product. These biotextiles are not typically used for industrial purposes.
The term "biotextiles" derives from the combination of "bio," referring to biology or living organisms, and "textiles," indicating woven or fibrous materials. It encompasses the interdisciplinary field of biomedical textiles, which focuses on the design, fabrication, and application of textile materials in healthcare and biomedical engineering. Biotextiles made from mycelium, vegetable biomass, bacterial cellulose, and recombinant protein based fibers are used as an alternative to synthetic textiles to prevent and reduce the high greenhouse gas emissions, water pollution, and landfill waste from the textile industry. Biotextiles are also used within healthcare and the biomedical engineering field as implantable devices such as surgical sutures, hernia repair fabrics, arterial grafts, artificial skin and parts of artificial hearts.
Introduction
The field of biotextiles has garnered significant attention due to its potential to revolutionize the textile industry by offering sustainable alternatives to conventional and environmentally harmful fabrics. Central to this innovation are raw materials derived from nature’s own processes, including mycelium, bacterial cellulose and vegetable and fruit biomass. These natural ingredients have potential to become a reliable source for the development of eco-friendly textiles, addressing issues with environmental degradation and ingredient depletion associated with traditional textile production. Processing of these materials offer abundant sources of natural fibers. Using the fibrous structures found in these materials and plant tissues, such as cotton, hemp, flax and more, its possible to create biodegradable and renewable textiles. Washing, drying and a variety of spinning techniques are common for processing of all textiles but the processing for biotextiles is expected to produce less environmentally harmful waste products due to the bio-remedial nature of many of the natural materials. Furthermore, advancements in processing have enabled the extraction of fibers for fashion from unconventional sources, including pineapple, banana, citrus fruits, animal byproducts and bone. These new developments make large contributions to the world of innovative fashion.
Mycelium-based textiles
Mycelium, the vegetative part of fungi, has emerged as a versatile and sustainable raw material for biotextiles. Mycelium typically grows underground or within its substrate such as soil, wood, decaying organic matter or waste residues. In mycelium-based biocomposites, the fungus consumes the carbohydrates to produce hyphae, a network of branching, thread-like structures. Through controlled growth processes, mycelium can be cultivated into a dense network of interwoven fibers, forming a durable biodegradable matrix suitable for textile applications. This cultivation depends on the temperature, moisture and pH of the media.
Pleurotus ostreatus
The commonly known fungal species, white-rot basidiomycetes, are capable of degrading polymeric carbohydrates and using them for growth. Pleurotus ostreatus is an edible white-rot fungus known to degrade cellulose, hemicellulose and lignin, hence reinforcing its potential to thrive on wastes such as wood, textile, and agricultural residues. The growth of P. ostreatus on textile residue and mycelium production was tested in the department of civil engineering in Ontario Canada. The conducted experiment proved the applicability of textile waste as a potential feedstock. However, the loss in biocomposite weight of 1%–5% has been further corroborated by the water loss in the sample and in fungal mycelium. Additionally, the maximum compressive strength was observed as 270 kPa using cotton-based biocomposite. Overall, a lightweight biocomposite was obtained which could be a potential alternative for polystyrene- based products. These findings show the ability of the fungus to thrive on polyester plastic in textiles and provide an alternative for converting this plastic material into bio-based materials. Additionally, by varying the mycelium growth, the plasticity and stiffness properties of the resultant biocomposite can be changed.
β-glucan/chitin complex
The β-glucan/chitin complex refers to the combination of two natural polysaccharides (β-glucan and chitin) found in fungal cell walls. This complex is a major component found in a variety of fungal cell walls and are also found in certain plants, algae, and bacteria. β-glucan contributes to the structural strength of the cell wall and plays roles in cell signaling, immune modulation and defense against pathogens. Chitin is a long-chain polymer of N-acetylglucosamine units, linked by β-glyosidic bonds. It provides structural support and protection to fungal cells, contributing to their rigidity and resilience. The addition of this complex to the growth components that make up the initial matrix that is the base of these emerging biotextiles provides a significant effect on the durability and usefulness of the processed result.
Vegetable biomass-based textiles
Polysaccharide-based polymers are made of fruit and vegetable origin, and the most promising biopolymer-yielding fibers include cellulose, starch, chitin/chitosan, pectin, alginate, and carrageenan. Soy, whey, and zein could also be obtained from vegetable sources. An example is Pinatex, a pineapple-based leather that is manufactured from the cellulose fibers of pineapple leaves. It is an environmentally friendly alternative to traditional leather due to its sustainability and adaptability. Additionally its lightweight, resilient and biodegradable nature has made it very popular for new and innovative fashion.
Algae-derived fibers (Alginate)
Alginate is a polysaccharide generated by brown algae, seaweed and specific species of bacteria.
Bacteria and seaweed alginate differ in composition, modifications, molecular mass, viscoelasticity, and polydispersity. These unique qualities lead to a wide range of applications, including alginate’s development of nanoparticles, nanotubes, microspheres, and microcapsules. Furthermore, the different types of sponges, hydrogels, foams, elastomers, and fibers that can be created with its growth and processing. It is widely employed in many facets of industrial fabrication. Alginate is commonly employed as a gelling agent, thickener, and stabilizer in a large variety of food products. Its ability to form gels under mild conditions makes it particularly useful for encapsulating flavors, vitamins, and other active ingredients. It is also used to develop hydrogels, printing pastes and sizing agents in biomedical, textile, cosmetic and agricultural industries. In the textile industry specifically, textile coatings, binders and finishes are the bulk of what alginate is used for, rather than formulating threads itself it reinforces the strength of other materials.
Bacterial cellulose-based textiles
Unlike plant-derived cellulose, bacterial cellulose offers superior mechanical properties, such as high tensile strength and flexibility, making it an attractive option for a wide range of textile applications. Moreover, the cultivation of bacterial cellulose can be achieved using simple fermentation processes, minimizing the environmental footprint associated with traditional textile manufacturing. Yeast, fungi and algae species including: the bacterium Pseudomonas fluorescens, the yeast Yarrowia lipolytica, the sponge Acanthella elongata, the algae Stoechospermum marginatum, and the fungus Candida albicans have all been researched for their ability to be used on substrates to create natural composites for biotextiles.
Yeast
Yeast is a single cell, fungal organism widely found in nature and plays important roles in various biological processes. Some species of yeast, such as Gluconacetobacter xylinus, are capable of producing cellulose through fermentation. This cultivation depends on the temperature, moisture and pH of the media. During fermentation, the yeast produces cellulose as an extracellular matrix, forming a dense network of cellulose fibers. This microbial cellulose can then be harvested, purified, and processed into textile fibers. This process is not consistent for most species of yeast though. The microbial cellulose produced by most yeast species can be processed into textile fibers after being reinforced with other natural or synthetic fibers using techniques such as spinning, weaving, or knitting. Depending on the desired characteristics, properties such as strength, softness, or moisture absorption can be controlled. The resulting textile materials can be used to produce a variety of products, including apparel, home textiles, and technical textiles. Using yeast in the biotextile industry contains many environmentally friendly and cost effective perks. Yeast fermentation can be carried out using renewable feedstocks such as agricultural residues, waste streams, or plant-based sugars, reducing reliance on finite resources and minimizing environmental impact. Additionally, microbial cellulose production is highly efficient, with relatively low energy and water requirements compared to conventional textile manufacturing processes. An emerging method in the creation of biotextiles is growing engineered yeast as cell factories that produce target proteins in succession. Other recent advances in synthetic biology and fermentation processes enable high-level expressions of recombinant proteins, using bacteria, yeasts, animal cells, and plants as biofactories.
Recombinant protein-based textiles
Collagen, fibroin, gelatin, casein, and actin are naturally from animal products. Collagen and silk are the most attractive biopolymers for developing biotextiles.
Collagen can be produced from a plethora of organisms and renewable sources. Collagen’s repeating amino acid sequence allows it to form a stable secondary protein structure of triple helices. These helices can further assemble into quaternary structures, allowing collagen to take on the form of fibrillar proteins. These protein building blocks could biofabricate abrasion-resistant, water-resistant, breathable, lightweight and durable materials with characteristics similar to leather. Natural silk has remarkable strength. The fibroin protein in silk consists of long, repetitive chains of amino acids, predominantly glycine, alanine, and serine. These amino acids are arranged in a specific sequence, forming a unique molecular structure that contributes to silk's remarkable properties. Silk has high tensile strength that can be attributed to its nano-crystalline and molecular structure (hydrogen bonds & β-sheet structure) and high degree of orientation. Significant efforts have been made to obtain recombinant silk fibroin, principally from the spider, dragline, or silkworm through genetic alteration. The developed protein is later isolated and processed into threads by techniques such as spinning.
Manufacture of biotextiles
Preface
The processing of different materials is determined by the origin of their species and substrate. While vegetable and fruit biomass-based textiles are formed into sheets, biotextiles made from proteins or bacterial cellulose are commonly drawn out during an extrusion and spun into a stronger thread. By cultivating plant and bacterial species on a determined substrate, it is possible to grow materials by harnessing their ability to digest and transform cellulose into natural composites. This process involves collecting them into proper scaffolds and executing physical and chemical treatment, so that these sheets of biomass visually resemble leather and exhibit comparable material and tactile properties. The processing of protein based textiles involves a variety of spinning techniques based on the type and quality that needs to be achieved.
Manufacturing of biotextiles
Before the production of biotextiles, monofilament structures were typically produced using extrusion techniques, where a single continuous filament was drawn from a polymer melt. These monofilaments can then be used directly or further processed into various biomedical devices, such as sutures, meshes, and vascular grafts. Biotextiles are created using multiple techniques, such as knitting, weaving, and braiding, to form the fabric-like structures used in biomedical applications. The three primary spinning techniques traditionally employed in fiber manufacturing are wet-spinning, dry-spinning, and melt-spinning.
Table1. The processing methods and applications of Biotextile
Electrospinning
Electrospinning is a technique that uses electrostatic forces to produce ultra fine fibers from polymer solutions or melts. These fibers have unique properties like large surface areas and high porosity, making them valuable for biomedical applications. Polymer solutions are ejected through a needle onto a collector plate by applying an electric field, forming nanofibers. These scaffolds show promise in tissue engineering, aiding in regenerating various human tissues and organs such as bone, skin, blood vessels, liver, and kidneys. They closely resemble the native extracellular matrix, facilitating cell attachment and proliferation. Electrospinning offers a versatile method for creating biocompatible scaffolds with simple structures for tissue engineering.
Melt spinning
Melt-spinning is a cost-effective method widely used in the textile industry for producing polymeric fibers without solvents. However, its application in biostructures is limited due to factors such as polymer decomposition at lower temperatures, inadequate control over melt temperature during spinning, and challenges in controlling the final fiber structure. In this process, polymer granules are melted in an extruder to form a spinning dope, then extruded through a spinneret and rapidly cooled to solidify the filament. Despite its drawbacks, melt-spinning of biopolymers has been explored for various bio-applications. The use of bio-based reinforcements is being investigated as a solution to overcome challenges associated with producing biotextiles via melt-spinning.
Dry spinning
Dry-spinning, an ancient spinning method, dissolves polymers in solvents, unlike melt-spinning. Polymer solutions are extruded through a spinneret and then passed through a heating column where the solvent evaporates, leaving dry fibers. Highly volatile solvents are needed for this process. Steam or hot air is utilized to solidify fibers and remove solvent. This technique suits polymers prone to thermal degradation and those unable to form viscous melts, offering specific surface characteristics. Traditional dry-spun polymers include acetate, triacetate, acrylics, modacrylics, aramid, and spandex fibers. Besides being complex and costly due to recovery processes and mass transfer mechanisms during solvent evaporation, dry-spinning provides fibers with unique properties.
Wet spinning
Wet-spinning, introduced with rayon fiber production, involves dissolving polymers in a suitable solvent before extrusion. Unlike dry-spinning, the solvent need not be volatile. During wet-spinning, the polymeric solution is extruded through a spinneret into a coagulation bath, leading to a phase inversion and precipitation. Natural and synthetic polymers, including gelatin, alginate, collagen, and cellulose, are processed into fibers via wet-spinning for various tissue engineering applications. This technique enables the production of fibers with large diameters and architectures with high porosity and interconnected open pore structures, facilitating cell penetration, adhesion, and proliferation.
Gel spinning
Gel spinning produces fibers with exceptional strength or other unique qualities. During extrusion, the polymer is not in a pure liquid condition. The polymer chains are linked at different locations in liquid crystal form, partially apart as they would be in a real solution. The resultant filaments have substantial inter-chain forces, which can significantly raise the fiber’s tensile strength additionally, the shear forces the liquid crystals to be arranged along the fiber axis during extrusion. Strength is further enhanced by the filaments' exceptionally high degree of alignment as they emerge from one another. Due to the filaments' first air-to-cool cooling phase, the method is known as dry-wet spinning.
Solution spinning
Solution spinning, encompassing wet and dry-jet wet spinning, creates continuous fibers from materials incapable of withstanding melting. This technique is applicable to manufacturing fibers from natural polymers and bio-based materials like cellulose, lignin, and proteins. As it relies on polymer solutions, solution spinning offers significant potential to enhance the functionality of wet-spun fibers through targeted formulations.
Grafting
In biotextiles, grafting onto surfaces refers to the process of attaching or bonding functional molecules, such as proteins, peptides, or polymers, onto the surface of textile materials. This process is often performed to modify the surface properties of textiles, such as enhancing biocompatibility, promoting cell adhesion, or enabling controlled drug release. Grafting onto surfaces can be achieved through various techniques, including chemical modification, plasma treatment, or surface coating methods. These modified biotextiles find applications in biomedical fields such as tissue engineering, wound healing, and medical implants, where tailored surface properties are critical for desired biological interactions.
Rotary jet spinning
Rotary jet spinning is a technique used in the production of biotextiles, which involves the extrusion of polymer solutions or melts through a rapidly rotating spinneret. As the polymer solution or melt exits the spinneret, it is subjected to centrifugal forces, forming fine fibers. These fibers are collected to create a nonwoven fabric or scaffold structure suitable for various biomedical applications. Rotary jet spinning offers advantages such as producing highly porous structures with controllable fiber diameter and alignment, making it promising for tissue engineering and drug delivery applications in biomedicine.
Use and applications
Consumer textile/fashion industry
Goat silk as milk byproduct
Researchers at the University of Wyoming have devised a method to introduce spider silk-spinning genes into goats, enabling the extraction of silk protein from the goats’ milk. This innovation has applications in various fields, including medicine, where the strength and elasticity of spider silk has been argued to be utilized in artificial ligaments, tendons, eye sutures, and jaw repair.
Traditionally, obtaining spider silk in sufficient quantities necessitates managing large populations of spiders, which often leads to territorial conflicts and cannibalism within the farmed spider population. To circumvent this challenge, scientists have genetically engineered goats to produce the silk protein exclusively in their milk. Through selective breeding, a percentage of the offspring inherit the silk protein gene, leading to higher yields of the silk protein.
The transgenic goats exhibit no discernible differences in health, appearance, or behavior compared to non-transgenic counterparts. In the future, the researchers aim to transfer silk genes into alfalfa plants, a move the researchers expect to further increase silk production. Researchers believe that alfalfa's widespread distribution and high protein content make it a promising candidate for large-scale silk protein synthesis.
Fruit waste textiles
In a collaboration between Danish fashion brand Ganni and Mexican biomaterials company Polybion, a unique prototype blazer was created using bacterial cellulose derived from industrial fruit waste. Unlike traditional leather, it has been stated that this fruit textile is environmentally friendly, with a significantly smaller carbon footprint.
A wide variety of fruit waste, particularly from mangoes, serves as the feedstock for the bacteria, transforming it into a growth medium. The resulting bacterial biomass, known as Celium, undergoes a tanning and finishing process similar to that of leather, yielding a durable material.
Mycelium textiles
Mycelium textiles start with a chosen substrate inoculated with fungal spores or mycelium culture. In a controlled environment, the mycelium grows throughout the substrate, forming a dense network of fibers. Once fully colonized, it's shaped and dried to create the desired form, undergoing additional treatments for properties like density or surface finish.
Mycelium textiles are a sustainable alternative to traditional textiles, made from the root structure of fungi. Mycelium, the vegetative part of fungi, can be grown into various shapes and forms, including textiles. These textiles are eco-friendly, biodegradable, and can be engineered to possess desired properties like flexibility, durability, and water resistance. It has been stated that this material is leathery.
Biomedical applications
Biotextile scaffolds for tissue regeneration
The development of a collagen biotextile scaffold for aiding in the healing process of large deep burn wounds has been achieved by researchers at UC Davis. This scaffold, utilizing a specially engineered biomaterial, has demonstrated efficacy in promoting the formation of new blood vessels and reducing complications associated with severe burns.
The study highlights the scaffold's ability to accelerate wound healing in mouse models and mitigate burn-related complications such as fluid loss and infection. Through testing different scaffold types, the research team observed that the combined treatment loaded with endothelial cells exhibited the highest wound healing rate.
Biotextile meshes
In the new paradigm of tissue engineering, professionals are trying to develop new textiles so that the body can form new tissue around these devices so it’s not relying solely on synthetic foreign implanted material. Graduate student Jessica Gluck has demonstrated that viable and functioning liver cells can be grown on textile scaffolds.
Environment and health impacts
The textile industry is one of the largest polluters of water and agricultural lands. This industry has caused numerous negative impacts on the environment as well as on the health of humans and ecosystems. Water pollution due to the discharge of wastewater containing textile dyes is the biggest environmental and ecological concerns due to the textile industry. There are several health concerns due to the discharge of wastewater contaminating with textile dyes such as respiratory problems, skin irritation, allergic reactions, and cancer. Biotextiles such as nettle and hemp denim are starting to be used as a replacement to use for synthetic textiles within the textile industry to try and prevent these negative environmental and health impacts.
Environmental impacts
There are several negative environmental impacts due to the modern day textile industry such as the discharge of textile dyes and pigments into wastewater, greenhouse gas emissions from production, energy and resource intensive production, and large amounts of landfill waste. Water pollution is the greatest environment concern since pigments and textile dyes do not naturally biodegrade over time, which causes direct health concerns for both humans and ecosystem wildlife.
Degradation of materials
One of the biggest concerns of the modern day textile industry is that synthetic textiles do not biodegrade over time. Approximately 700,000 tons of dyes are being used in the textile industry every year. 10 to 15 percent of the dyes that are used during clothing production remain unfixed dyes. These dyes and pigments contaminate wastewater and discharge into local water bodies. Approximately 20 percent of wastewater produced globally is from the textile industry. Textile dyes degrade the aesthetic quality of these local water bodies and prevent sunlight from penetrating through the surface water. These dyes harm aquatic ecosystems since water pollution impairs photosynthesis and leads to a hypoxic environment unable to support life. Textile dyes contamination also harm humans since the toxins within these dyes can bioaccumulate and biomagnify throughout the food chain, causing health concerns to species at the top of the food chain such as humans.
The application of bacterial isolates offers a promising solution to improve water quality in dye contaminated marine environments. Bacterial isolates degrade and remove textile dyes from wastewater through several methods, including biodegradation and biosorption of dyes. They have the ability to biodegrade complex dye molecules into simple one through enzymatic reactions. Bacterial isolates break down the dye molecules by reducing their color and toxicity, which improves ecosystems. There are many advantages to biodegradation, including a high dye removal efficiency, low cost, and the fact that many microorganisms such as bacteria, fungi, algae and enzymes can be used. However, the disadvantages are that this process requires a favorable environment for these microorganisms to grow, it generates biological sludge and is a slow process. Bacterial isolates can also adsorb complex dye molecules onto the surface of their cells. This adsorption process involves the physical binding of dye molecules to bacterial cell walls, and then the removal of these isolates from wastewater. The advantages of this process are that it has a high dye removal efficiency and a short reaction time. There are disadvantages as well since this processes is not applicable to all types of dyes and it generates a toxic waste product.
Closed-loop recycling
There are several other harmful environmental impact from synthetic textile production, including large amount of greenhouse gas emissions, high energy consumption and landfill waste. A typical textile mill consumes approximately 1.6 million liters of water to produce 8,000 kilograms of fabric. This is a worldwide problem since the textile industry contributes to about 10 percent of global greenhouse gas emissions. During 2016 alone, only 1 percent of the 180,000 tons of textile waste produced was recycled into new clothes. The remaining old textile fibers ended up in a landfill as waste.
One solution that is currently being implemented within the textile industry to combat these issues is a closed loop recycling system. In the context of the textile industry, closed loop recycling involves collecting used textiles, processing them through various mechanical, chemical or biological recycling methods to turn used, worn down textiles into new textiles. Within a closed loop recycling system, textiles can either be recycled into a similar product, upcycled into a new, higher quality product, or downcycled into a new, lower quality product. This approach reduces waste, conserves resources, and minimizes the environmental impact of textile production by promoting a circular economy where materials are recycled and reused in a continuous, closed loop. As demonstrated in the figure, the enzyme groups cellulase, PETase, and keratinase are used within the closed recycling loop to break down old textiles such as polyester and nylon into amino acids, glucose, or synthetic monomer building blocks. These monomers then undergo chemical polymerization and are combined to create high quality polylactic acid (PLA), polyhydroxyalkanoates (PHAs), silk, and bacterial cellulose polymers. Afterwards, these synthesized polymers are used to create man made, biodegradable fibers, which are then used to make new, biodegradable textiles. These textiles are used until their become worn down and are depolymerized to continue the closed recycling loop.
Sustainable biotextiles
Biotextiles are used as an alternative to synthetic textiles to prevent and combat the excess amounts of water and waste pollution from the textile industry. Large brands such as Nike, Adidas, Hermes and Stella McCartney are starting to use biotextiles for some of their fashion collections. One solution created by sustainable textile companies such as Pangaia and Agraloop is denim made out of nettle and hemp plants. Nettle plants are a renewable, biodegradable resource that can be used to design nettle denim by mixing organic cotton and Himalayan nettle. Hemp is another plant that is being looked into as an alternative denim material by these two companies since it is more durable and only consumes about a tenth of the water needed for cotton.
The company Collina Strada is developing another biotextile solution called rose sylk. Rose sylk is an organic, biodegradable cellulose fiber that is derived from the natural waste of rose stems and bushes. Collina Strada promotes upcycling and reuse of old textiles by using factories to turn Ghana’s textile waste materials into insulation for coats and houses. A third solution involves clothing made from a pineapple based leather alternative, which is currently being used by major brands such as Nike, Hugo Boss and H&M. This pineapple leather alternative is made from cellulose fibers extracted from pineapple leaves and stalks. The use of agriculture pineapple waste instead of traditional leather has prevented approximately 264 tons of carbon dioxide from being emitted into the atmosphere, reducing greenhouse gas emissions.
Health impacts
There are several negative health impacts due to the discharge of wastewater containing textile dyes into local water bodies. These health issues include respiratory problems, skin irritation, allergic reactions, and cancer. Some of the respiratory problems that textile dyes cause are coughing, wheezing, asthma, and sneezing. Textile dye contamination causes skin irritation and allergic reaction symptoms such as itchy and watery eyes, sore eyes, an irritated and blocked nose and sniffling. Additionally, wastewater effluent containing both textile dyes and trace metals can cause long term health issues such as severe skin irritation, dermatitis, skin ulcerations, and even cancer.
Biocompatibility
Biocompatibility of textiles with the human body is of utmost importance when analyzing how both synthetic and biotextiles affect human health. The materials used to create textiles need to be compatible with human bodies and other animals to avoid negative health impacts from happening to these organisms. Synthetic textiles cause many negative health effects on both humans and ecosystem wildlife due to the fact that they persist in the environment and do not biodegrade over time. Biotextiles, on the other hand, do not cause any known negative health concerns to humans or animals since they are produced with naturally occurring biological sources that can easily biodegrade over time.
See also
Technical textiles
Biomaterials
Mycelium-based materials
Textiles
References
Biological engineering
Textiles | Biotextile | [
"Engineering",
"Biology"
] | 6,142 | [
"Biological engineering"
] |
10,839,099 | https://en.wikipedia.org/wiki/Arch%20Moscow | Arch Moscow is an international exhibition of architecture and design held annually since 1995.
It is held in Moscow, Russia, in the Central House of Artist in the Crimean shaft (Krymsky Val). The organizer is Expo Park Company.
References
External links
Press releases
Arch Moscow 2012 – press releases by cih.ru
Arch Moscow 2010 website
Photo gallery
Arch Moscow 2011
Arch Moscow 2010
Arch Moscow 2009
Arch Moscow 2008
Arch Moscow 2008 info
Arch Moscow 2007
Arch Moscow 2006
Arch Moscow 2005
Arch Moscow 2004
Arch Moscow 2003
Arch Moscow 2002
Architecture festivals
Architecture in Russia
Culture in Moscow
Festivals established in 1995
Tourist attractions in Moscow
Trade fairs in Russia | Arch Moscow | [
"Engineering"
] | 126 | [
"Architecture festivals",
"Architecture"
] |
10,842,431 | https://en.wikipedia.org/wiki/Hammerhead%20ribozyme | The hammerhead ribozyme is an RNA motif that catalyzes reversible cleavage and ligation reactions at a specific site within an RNA molecule. It is one of several catalytic RNAs (ribozymes) known to occur in nature. It serves as a model system for research on the structure and properties of RNA, and is used for targeted RNA cleavage experiments, some with proposed therapeutic applications. Named for the resemblance of early secondary structure diagrams to a hammerhead shark, hammerhead ribozymes were originally discovered in two classes of plant virus-like RNAs: satellite RNAs and viroids. They are also known in some classes of retrotransposons, including the retrozymes. The hammerhead ribozyme motif has been ubiquitously reported in lineages across the tree of life.
The self-cleavage reactions, first reported in 1986, are part of a rolling circle replication mechanism. The hammerhead sequence is sufficient for self-cleavage and acts by forming a conserved three-dimensional tertiary structure.
Catalysis
In its natural state, a hammerhead RNA motif is a single strand of RNA. Although the cleavage takes place in the absence of protein enzymes, the hammerhead RNA itself is not a catalyst in its natural state, as it is consumed by the reaction (i.e. performs self-cleavage) and therefore cannot catalyze multiple turnovers.
Trans-acting hammerhead constructs can be engineered such that they consist of two interacting RNA strands, with one strand composing a hammerhead ribozyme that cleaves the other strand. The strand that gets cleaved can be supplied in excess, and multiple turnover can be demonstrated and shown to obey Michaelis-Menten kinetics, typical of protein enzyme kinetics. Such constructs are typically employed for in vitro experiments, and the term "hammerhead RNA" has become in practice synonymous with the more frequently used "hammerhead ribozyme".
The minimal trans-acting hammerhead ribozyme sequence that is catalytically active consists of three base-paired stems flanking a central core of 15 conserved (mostly invariant) nucleotides, as shown. The conserved central bases, with few exceptions, are essential for ribozyme's catalytic activity. Such hammerhead ribozyme constructs exhibit in vitro a turnover rate (kcat) of about 1 molecule/minute and a Km on the order of 10 nanomolar.
The hammerhead ribozyme is arguably the best-characterized ribozyme. Its small size, thoroughly-investigated cleavage chemistry, known crystal structure, and its biological relevance make the hammerhead ribozyme particularly well-suited for biochemical and biophysical investigations into the fundamental nature of RNA catalysis.
Hammerhead ribozymes may play an important role as therapeutic agents; as enzymes which tailor defined RNA sequences, as biosensors, and for applications in functional genomics and gene discovery.
Species distribution
In 1986, the first hammerhead ribozymes were found in RNA plant pathogens like viroids and viral satellites. One year later, a hammerhead ribozyme was also reported in the satellite DNA of newt genomes. New examples of this ribozyme were then found in the genomes of unrelated organisms like schistosomes, cave crickets, Arabidopsis thaliana and a few mammals like rodents and the platypus. In 2010, it was found that the hammerhead ribozyme occurs in a wide variety of bacterial and eukaryotic genomes, including in humans. Similar reports confirmed and extended these observations, unveiling the hammerhead ribozyme as a ubiquitous catalytic RNA in all life kingdoms.
Most eukaryotic hammerhead ribozymes are related to a kind of short interspersed retroelements (SINEs) called retrozymes, which express as small circular RNAs. However, an exceptional group of strikingly conserved hammerheads can be found in the genomes of all amniotes. These hammerhead ribozymes (the so-called HH9 and HH10) occur in the introns of a few specific genes and point to a preserved biological role during pre-mRNA biosynthesis. In 2021, novel Hepatitis D virus genomes of circular RNA from diverse animals were found to encode hammerhead ribozymes similar to those present in plant viroids and viral satellites. A massive bioinformatic search of deltavirus-like agents around the globe has uncovered hundreds of examples of circular RNA genomes carrying hammerhead motifs, indicating that not only this ribozyme but small circular RNAs with ribozymes are ubiquitous molecules in the biosphere.
Chemistry of catalysis
The hammerhead ribozyme carries out a very simple chemical reaction that results in the breakage of the substrate strand of RNA, specifically at C17, the cleavage-site nucleotide. Although RNA cleavage is often referred to as hydrolysis, the mechanism employed does not in fact involve the addition of water. Rather, the cleavage reaction is simply an isomerization that consists of rearrangement of the linking phosphodiester bond. It is the same reaction, chemically, that occurs with random base-mediated RNA degradation, except that it is highly site-specific and the rate is accelerated 10,000-fold or more.
Cleavage by phosphodiester isomerization
The cleavage reaction is a phosphodiester isomerization reaction that is initiated by abstraction of the cleavage-site ribose 2’-hydroxyl proton from the 2’-oxygen, which then becomes the attacking nucleophile in an “in-line” or SN2(P)-like reaction, although it is not known whether this proton is removed prior to or during the chemical step of the hammerhead cleavage reaction. (The cleavage reaction is technically not bimolecular, but behaves in the same way a genuine SN2(P) reaction does; it undergoes inversion of configuration subsequent to forming an associative transition-state consisting of a pentacoordinated oxyphosphrane.) The attacking and leaving group oxygens will both occupy the two axial positions in the trigonal bipyramidal transition-state structure as is required for an SN2-like reaction mechanism.
The 5’-product, as a result of this cleavage reaction mechanism, possesses a 2’,3’-cyclic phosphate terminus, and the 3’-product possesses a 5’-OH terminus, as with nonenzymatic alkaline cleavage of RNA. The reaction is therefore reversible, as the scissile phosphate remains a phosphodiester, and may thus act as a substrate for hammerhead RNA-mediated ligation without a requirement for ATP or a similar exogenous energy source. The hammerhead ribozyme-catalyzed reaction, unlike the formally identical non-enzymatic alkaline cleavage of RNA, is a highly sequence-specific cleavage reaction with a typical turnover rate of approximately 1 molecule of substrate per molecule of enzyme per minute at pH 7.5 in 10 mM Mg2+ (so-called “standard reaction conditions” for the minimal hammerhead RNA sequence), depending upon the sequence of the particular hammerhead ribozyme construct measured. This represents an approximately 10,000-fold rate enhancement over the nonenzymatic cleavage of RNA.
Requirement for divalent metal ions
All ribozymes were originally thought to be metallo-enzymes. It was assumed that divalent metal ions like Mg2+ were thought to have two roles: Promote proper folding of RNA and to form the catalytic core. Since RNA itself did not contain enough variation in the functional groups, metal ions were thought to play a role at the active site, as was known about proteins. The proposed mechanism for the Mg2+ ion was: the deprotonation of the 2'-OH group by a Magnesium.aqua.hydroxy complex bound by the pro-R oxygen at the phosphate-cleavage site, followed by nucleophilic attack of the resultant 2'-alkaoxide on the scissile phosphate forming a pentacoordinate phosphate intermediate. The last step is the departing of the 5' leaving group, yielding a 2',3'-cyclic phosphate with an inverted configuration.
It was presumed that hexahydrated magnesium ions, which exist in equilibrium with magnesium hydroxide, could play the roles of general acid and general base, in a way analogous to those played by two histidines in RNase A. An additional role for divalent metal ions has also been proposed in the form of electrostatic stabilization of the transition-state.
Not a metallo-enzyme
In 1998 it was discovered that the hammerhead ribozyme, as well as the VS ribozyme and hairpin ribozyme, do not require the presence of metal ions for catalysis, provided a sufficiently high concentration of monovalent cation is present to permit the RNA to fold. This discovery suggested that the RNA itself, rather than serving as an inert, passive scaffold for the binding of chemically active divalent metal ions, is instead itself intimately involved in the chemistry of catalysis. The latest structural results, described below, indeed confirm that two invariant nucleotides, G12 and G8, are positioned consistent with roles as the general base and general acid in the hammerhead cleavage reaction.
Strictly speaking, therefore, the hammerhead ribozyme cannot be a metallo-enzyme.
Primary and secondary structure
Minimal ribozyme
The minimal hammerhead sequence that is required for the self-cleavage reaction includes approximately 13 conserved or invariant "core" nucleotides, most of which are not involved in forming canonical Watson-Crick base-pairs. The core region is flanked by Stems I, II and III, which are in general made of canonical Watson-Crick base-pairs but are otherwise not constrained with respect to sequence. The catalytic turnover rate of minimal hammerhead ribozymes is ~ 1/min (a range of 0.1/min to 10/min is commonly observed, depending upon the nonconserved sequences and the lengths of the three helical stems) under standard reaction conditions of high Mg2+ (~10 mM), pH 7.5 and 25 °C. Much of the experimental work carried out on hammerhead ribozymes has used a minimal construct.
Type I, type II and type III hammerhead RNA
Structurally the hammerhead ribozyme is composed of three base paired helices, separated by short linkers of conserved sequences. These helices are called I, II and III. Hammerhead ribozymes can be classified into three types based on which helix the 5' and 3' ends are found in. If the 5' and 3' ends of the sequence contribute to stem I then it is a type I hammerhead ribozyme, to stem II is a type II and to stem III then it is a type III hammerhead ribozyme. Of the three possible topological types, type I can be found in the genomes of prokaryotes, eukaryotes and RNA plant pathogens, whereas type II have been only described in prokaryotes and type III are mostly found in plants, plant pathogens and prokaryotes.
Full-length ribozyme
The full-length hammerhead ribozyme consists of additional sequence elements in stems I and II that permit additional tertiary contacts to form. The tertiary interactions stabilize the active conformation of the ribozyme, resulting in cleavage rates up to 1000-fold greater than those for corresponding minimal hammerhead sequences.
Tertiary structure
Minimal
The minimal hammerhead ribozyme has been exhaustively studied by biochemists and enzymologists as well as by X-ray crystallographers, NMR spectroscopists, and other practitioners of biophysical techniques. The first detailed three-dimensional structural information for a hammerhead ribozyme appeared in 1994 in the form of an X-ray crystal structure of a hammerhead ribozyme bound to a DNA substrate analogue, published in Nature by Pley, Flaherty and McKay. Subsequently, an all-RNA minimal hammerhead ribozyme structure was published by Scott, Finch and Klug in Cell in early 1995.
The minimal hammerhead ribozyme is composed of three base paired helices, separated by short linkers of conserved sequence as shown in the crystal structure. These helices are called I, II and III. The conserved uridine-turn links helix I to helix II and usually contains the sequence CUGA. Helix II and III are linked by a sequence GAAA. The cleavage reaction occurs between helix III and I, and is usually a C.
The structure of a full-length ribozyme shows that there are extensive interactions between the loop of stem II and stem I.
Similar structures are observed in other ribozymes such as hatchet ribozymes.
Structure-function
Despite the observations of hammerhead ribozyme catalysis in a crystal of the minimal hammerhead sequence in which the crystal lattice packing contacts by necessity confined the global positions of the distal termini of all three flanking helical stems, many biochemical experiments designed to probe transition-state interactions and the chemistry of catalysis appeared to be irreconcilable with the crystal structures.
For example, the invariant core residues G5, G8, G12 and C3 in the minimal hammerhead ribozyme were each observed to be so fragile that changing even a single exocyclic functional group on any one of these nucleotides results in a dramatic reduction or abolition of catalytic activity, yet few of these appeared to form hydrogen bonds involving the Watson-Crick faces of these nucleotide bases in any of the minimal hammerhead structures, apart from a G-5 interaction in the product structure.
A particularly striking and only recently observed example consisted of G8 and G12, which were identified as possible participants in acid/base catalysis. Once it was demonstrated that the hammerhead RNA does not require divalent metal ions for catalysis, it gradually became apparent that the RNA itself, rather than passively bound divalent metal ions, must play a direct chemical role in any acid-base chemistry in the hammerhead ribozyme active site. It was however completely unclear how G12 and G8 could accomplish this, given the original structures of the minimal hammerhead ribozyme.
Other concerns included an NOE between U4 and U7 of the cleaved hammerhead ribozyme that had also been observed during NMR characterization, which suggested that these nucleotide bases must approach one another closer than about 6 Å, although close approach of U7 to U4 did not appear to be possible from the crystal structure. Finally, as previously discussed, the attacking nucleophile in the original structures, the 2’-OH of C17, was not in a position amenable to in-line attack upon the adjacent scissile phosphate.
Perhaps most worrisome were experiments that suggested the A-9 and scissile phosphates must come within about 4 Å of one another in the transition-state, based upon double phosphorothioate substitution and soft metal ion rescue experiments; the distance between these phosphates in the minimal hammerhead crystal structure was about 18 Å, with no clear mechanism for close approach if the Stem II and Stem I A-form helices were treated as rigid bodies. Taken together, these results appeared to suggest that a fairly large-scale conformational change must have taken place in order to reach the transition-state within the minimal hammerhead ribozyme structure.
For these reasons, the two sets of experiments (biochemical vs. crystallographic) appeared not only to be at odds, but to be completely and hopelessly irreconcilable, generating a substantial amount of discord in the field. No compelling evidence for dismissing either set of experimental results was ever made successfully, although many claims to the contrary were made in favor of each.
Full-length
In 2006 a 2.2 Å resolution crystal structure of the full-length hammerhead ribozyme was obtained. This new structure (shown on the right) appears to resolve the most worrisome of the previous discrepancies. In particular, C17 is now positioned for in-line attack, and the invariant residues C3, G5, G8 and G12 all appear involved in vital interactions relevant to catalysis. Moreover, the A9 and scissile phosphates are observed to be 4.3 Å apart, consistent with the idea that, when modified, these phosphates could bind a single thiophilic metal ion. The structure also reveals how two invariant residues, G-12 and G-8, are positioned within the active site consistent with their previously proposed role in acid/base catalysis. G12 is within hydrogen bonding distance to the 2’–O of C17, the nucleophile in the cleavage reaction, and the ribose of G8 hydrogen bonds to the leaving group 5’-O. (see below), while the nucleotide base of G8 forms a Watson-Crick pair with the invariant C3. This arrangement permits one to suggest that G12 is the general base in the cleavage reaction, and that G8 may function as the general acid, consistent with previous biochemical observations. G5 hydrogen bonds to the furanose oxygen of C17, helping to position it for in-line attack. U4 and U7, as a consequence of the base-pair formation between G8 and C3, are now positioned such that an NOE between their bases is easily explained.
The crystal structure of the full-length hammerhead ribozyme thus clearly addresses all of the major concerns that appeared irreconcilable with the previous crystal structures of the minimal hammerhead ribozyme.
Structure and catalysis
The tertiary interactions in the full-length hammerhead ribozyme stabilize what strongly appears to be the active conformation. The nucleophile, the 2'-oxygen of the cleavage-site nucleotide, C17, is aligned almost perfectly for an in-line attack (the SN2(P) reaction). G12 is positioned within hydrogen bonding distance of this nucleophile, and therefore would be able to abstract a proton from the 2'-oxygen if G12 itself becomes deprotonated. The 2'-OH of G8 forms a hydrogen bond to the 5'-leaving group oxygen, and therefore potentially may supply a proton as negative charge accumulates on the 5'-oxygen of the ribose of A1.1.
The most likely explanation is then that G12, in the deprotonated form, is the general base, and the ribose of G8 is the general acid. The apparent kinetic pKa of the hammerhead ribozyme is 8.5, whereas the pKa of guanosine is about 9.5. It is possible that the pKa of G12 is perturbed from 9.5 to 8.5 in the hammerhead catalytic core; this hypothesis is currently the subject of intense investigation.
If the invariant G8 is changed to C8, hammerhead catalysis is abolished. However, a G8C + C3G double-mutant that maintains the G8-C3 base pair found in the full-length hammerhead restores most of the catalytic activity. The 2'-OH of G8 has also been observed to be essential for catalysis; replacement of G8 with deoxyG8 greatly reduces the rate of catalysis, suggesting the 2'-OH is indeed crucial to the catalytic mechanism.
The close approach of the A9 and scissile phosphates requires the presence of a high concentration of positive charge. This is probably the source of the observation that divalent metal ions are required at low ionic strength, but can be dispensed with at higher concentrations of monovalent cations.
The reaction thus likely involves abstraction of the 2'-proton from C17, followed by nucleophilic attack upon the adjacent phosphate. As the bond between the scissile phosphorus and the 5'-O leaving group begins to break, a proton is supplied from the ribose of G8, which then likely reprotonates at the expense of a water molecule observed to hydrogen bond to it in the crystal structure.
Therapeutic applications
Modified hammerhead ribozymes are being tested as therapeutic agents. Synthetic RNAs containing sequences complementary to the mutant SOD1 mRNA and sequences necessary to form the hammerhead catalytic structure are being studied as a possible therapy for amyotrophic lateral sclerosis. Work is also underway to find out whether they could be used to engineer HIV-resistant lines of T-cells. Modified hammerhead ribozyme adenoviruses have been shown to be potent in treating cancer both in vitro and in vivo.
The therapeutic use of trans-cleaving hammerhead ribozymes has been severely hampered by its low-level activity in vivo. The true catalytic potential of trans-cleaving hammerhead ribozymes may be recouped in vivo and therapeutic derivatives are likely to complement other nucleic acid hybridizing therapeutic strategies. Already there are hammerhead ribozymes which are close to clinical application.
References
External links
Bill Scott's lab pages on the hammerhead ribozyme
Marcos de la Peña's lab page on the hammerhead ribozyme
RNA
Ribozymes | Hammerhead ribozyme | [
"Chemistry"
] | 4,444 | [
"Catalysis",
"Ribozymes"
] |
10,843,099 | https://en.wikipedia.org/wiki/Egor%20Popov | Egor Pavlovich Popov (; February 6, 1913 – April 19, 2001) was a structural and seismic engineer who helped transform the design of buildings, structures, and civil engineering around earthquake-prone regions.
A relative of inventor Alexander Stepanovich Popov, Egor Popov was born in Kiev, Russian Empire and after moving to the United States of America in 1927, he eventually earned a B.S. from UC Berkeley, his master's degree from MIT and his doctorate degree from Stanford in 1946.
During his career, Popov was primarily famous for his work doing research for the University of California, Berkeley. Some of his accomplishments include: working with buckling problems for NASA in Houston, Texas, involvement with the San Francisco–Oakland Bay Bridge, assisting with pipe testing for the Trans-Alaskan Pipeline, developing the Steel Moment Resisting Frame (resistance to earthquake forces), and eccentrically braced frames (ebf's).
Textbooks
Introduction to Mechanics of Solids, Prentice Hall, 1968.
Mechanics of Materials, 2nd ed., Prentice Hall, 1976.
Engineering Mechanics of Solids, 2nd ed., Prentice Hall, 1998.
References
Further reading
Egor Popov Connections: The EERI Oral History Series. Oakland, CA: Earthquake Engineering Research Institute. 1994. ISBN 0-943198-12-7.
1913 births
2001 deaths
American civil engineers
Earthquake engineering
Soviet emigrants to the United States
University of California, Berkeley faculty
American people of Russian descent
University of California, Berkeley alumni
Massachusetts Institute of Technology alumni
Stanford University alumni
20th-century American engineers | Egor Popov | [
"Engineering"
] | 320 | [
"Structural engineering",
"Earthquake engineering",
"Civil engineering"
] |
10,843,628 | https://en.wikipedia.org/wiki/Glutamate%20carboxypeptidase%20II | TAH molecule, also known as N-acetyl-L-aspartyl-L-glutamate peptidase I (NAALADase I), NAAG peptidase, or prostate-specific membrane antigen (PSMA) is an enzyme that in humans is encoded by the FOLH1 (folate hydrolase 1) gene. Human GCPII contains 750 amino acids and weighs approximately 84 kDa.
GCPII is a zinc metalloenzyme that resides in membranes. Most of the enzyme resides in the extracellular space. GCPII is a class II membrane glycoprotein. It catalyzes the hydrolysis of N-acetylaspartylglutamate (NAAG) to glutamate and N-acetylaspartate (NAA) according to the reaction scheme to the right.
Neuroscientists primarily use the term NAALADase in their studies, while those studying folate metabolism use folate hydrolase, and those studying prostate cancer or oncology, PSMA. All refer to the same protein glutamate carboxypeptidase II.
Discovery
GCPII is mainly expressed in four tissues of the body, including prostate epithelium, the proximal tubules of the kidney, the jejunal brush border of the small intestine and ganglia of the nervous system.
Indeed, the initial cloning of the cDNA encoding the gene expressing PSMA was accomplished with RNA from a prostate tumor cell line, LNCaP. PSMA was first detected in the LNCaP cell line using the murine monoclonal antibody 7E11-C5.3 (also known by the name capromab), generated from murine spleen cells treated with LNCaP cell membranes. However, 7E11-C5.3 exclusively targets an intracellular epitope of PSMA, thus only binding to dead or dying cells. PSMA shares homology with the transferrin receptor and undergoes endocytosis but the ligand for inducing internalization has not been identified. It was found that PSMA was the same as the membrane protein in the small intestine responsible for removal of gamma-linked glutamates from polygammaglutamate folate. This enables the freeing of folic acid, which then can be transported into the body for use as a vitamin. This resulted in the cloned genomic designation of PSMA as FOLH1 for folate hydrolase.
PSMA(FOLH1) + folate polygammaglutamate(n 1-7) → PSMA (FOLH1) + folate(poly)gammaglutamate(n-1) + glutamate continuing until releasing folate.
Structure
The three domains of the extracellular portion of GCPII—the protease, apical and C-terminal domains—collaborate in substrate recognition. The protease domain is a central seven-stranded mixed β-sheet. The β-sheet is flanked by 10 α-helices. The apical domain is located between the first and the second strands of the central β-sheet of the protease domain. The C-terminal domain is an Up-Down-Up-Down four-helix bundle. The apical, protease and C-terminal domains create a pocket that facilitates substrate binding.
The central pocket is approximately 2 nanometers in depth and opens from the extracellular space to the active site. This active site contains two zinc ions. During inhibition, each acts as a ligand to an oxygen in 2-PMPA or phosphate. There is also one calcium ion coordinated in GCPII, far from the active site. It has been proposed that calcium holds together the protease and apical domains. In addition, human GCPII has ten sites of potential glycosylation, and many of these sites (including some far from the catalytic domain) affect the ability of GCPII to hydrolyze NAAG.
The human FOLH1 gene is positioned at the 11p11.12 locus of chromosome 11. The gene is 4,110 base pairs in length and composed of 22 exons. The encoded protein is a member of the M28 peptidase family. Orthologs of the human FOLH1 gene have also been identified in other mammals, including the 7 D3; 7 48.51 cM locus in mice. The FOLH1 gene has multiple potential start sites and splice forms, giving rise to differences in membrane protein structure, localization, and carboxypeptidase activity based on the parent tissue.
Enzyme kinetics
The hydrolysis of NAAG by GCPII obeys Michaelis–Menten kinetics. Hlouchková et al. (2007) determined the Michaelis constant (Km) for NAAG to be 1.2*10−6 ± 0.5*10−6 M and the turnover number (kcat) to be 1.1 ± 0.2 s−1.
Role in cancer
Human PSMA is highly expressed in the prostate, roughly a hundred times greater than in most other tissues. In some prostate cancers, PSMA is the second-most upregulated gene product, with an 8- to 12-fold increase over levels in noncancerous prostate cells. Because of this high expression, PSMA is being developed as potential biomarker for therapy and imaging of some cancers. In human prostate cancer, the higher expressing tumors are associated with quicker time to progression and a greater percentage of patients suffering relapse. In vitro studies using prostate and breast cancer cell lines with decreased PSMA levels showed a significant decrease in the proliferation, migration, invasion, adhesion and survival of the cells.
Imaging
PSMA is the target of several nuclear medicine imaging agents for prostate cancer. PSMA expression can be imaged with gallium-68 PSMA or fluorine-18 PSMA for positron emission tomography. This uses a radiolabelled small molecule that binds with high affinity to the extra-cellular domain of the PSMA receptor. Previously, an antibody targeting the intracellular domain (indium-111 capromabpentide, marketed as Prostascint) was used, although detection rate was low.
In 2020, the results of a randomised phase 3 trial ("ProPSMA study") was published comparing Gallium-68 PSMA PET/CT to standard imaging (CT and bone scan). This 300 patient study conducted at 10 study sites demonstrated superior accuracy of PSMA PET/CT (92% vs 65%), higher significant change in management (28% vs 15%), less equivocal/uncertain imaging findings (7% vs 23%) and lower radiation exposure (10 mSv vs 19 mSv). The study concludes that PSMA PET/CT is a suitable replacement for conventional imaging, providing superior accuracy, to the combined findings of CT and bone scanning. This new technology was approved by the FDA on Dec 1, 2020. A dual-modality small molecule that is positron-emitting (18F) and fluorescent targets PSMA and was tested in humans. The molecule found the location of primary and metastatic prostate cancer by PET, fluorescence-guided removal of cancer, and detects single cancer cells in tissue margins.
A Human-Derived, Genetic, Positron-emitting and Fluorescent (HD-GPF) reporter system uses a human protein, PSMA and non-immunogenic, and a small molecule that is positron-emitting (18F) and fluorescent for dual modality PET and fluorescence imaging of genome modified cells, e.g. cancer, CRISPR/Cas9, or CAR T-cells, in an entire mouse.
Therapy
PSMA can also be used as a target for treatment in unsealed source radiotherapy. Lutetium-177 is a beta emitter which can be combined with PSMA-targeting molecules to deliver treatment to prostate tumours. A prospective phase II study demonstrated a response (as defined by reduction in PSA of 50% or more) in 64% of men. Common side effects include dry mouth, dry fatigue, nausea, dry eyes and thrombocytopenia (reduction in platelets). A follow-up randomized phase II trial, the ANZUP TheraP trial, compared Lu-177 PSMA-617 radionuclide therapy to cabazitaxel chemotherapy, demonstrating superior response rates, lower toxicity and better patient-reported outcomes with Lu-177 PSMA(). The results of randomised trial VISION trial were positive with 40% reduction in mortality and 5 months increase in survival. phase III VISION trial.
Neurotransmitter degradation
For those studying neural based diseases, NAAG is one of the three most prevalent neurotransmitters found in the central nervous system and when it catalyzes the reaction to produce glutamate it is also producing another neurotransmitter. Glutamate is a common and abundant excitatory neurotransmitter in the central nervous system; however, if there is too much glutamate transmission, this can kill or at least damage neurons and has been implicated in many neurological diseases and disorders therefore the balance that NAAG peptidase contributes to is quite important.
Potential therapeutic applications
Function in the brain
GCPII has been shown to both indirectly and directly increase the concentration of glutamate in the extracellular space. GCPII directly cleaves NAAG into NAA and glutamate. NAAG has been shown, in high concentration, to indirectly inhibit the release of neurotransmitters, such as GABA and glutamate. It does this through interaction with and activation of presynaptic group II mGluRs. Thus, in the presence of NAAG peptidase, the concentration of NAAG is kept in check, and glutamate and GABA, among other neurotransmitters, are not inhibited.
Researchers have been able to show that effective and selective GCPII inhibitors are able to decrease the brain's levels of glutamate and even provide protection from apoptosis or degradation of brain neurons in many animal models of stroke, amyotrophic lateral sclerosis, and neuropathic pain. This inhibition of these NAAG peptidases, sometimes referred to as NPs, are thought to provide this protection from apoptosis or degradation of brain neurons by elevating the concentrations of NAAG within the synapse of neurons. NAAG then reduces the release of glutamate while stimulating the release of some trophic factors from the glia cells in the central nervous system, resulting in the protection from apoptosis or degradation of brain neurons. It is important to note, however, that these NP inhibitors do not seem to have any effect on normal glutamate function. The NP inhibition is able to improve the naturally occurring regulation instead of activating or inhibiting receptors that would disrupt this process. Research has also shown that small-molecule-based NP inhibitors are beneficial in animal models that are relevant to neurodegenerative diseases. Some specific applications of this research include neuropathic and inflammatory pain, traumatic brain injury, ischemic stroke, schizophrenia, diabetic neuropathy, amyotrophic lateral sclerosis, as well as drug addiction. Previous research has found that drugs that are able to reduce glutamate transmission can relieve the neuropathic pain, although the resultant side-effects have limited a great deal of their clinical applications. Therefore, it appears that, since GCPII is exclusively recruited for the purpose of providing a glutamate source in hyperglutamatergic and excitotoxic conditions, this could be an alternative to avert these side-effects. More research findings have shown that the hydrolysis of NAAG is disrupted in schizophrenia, and they have shown that specific anatomical regions of the brain may even show discrete abnormalities in the GCP II synthesis, so NPs may also be therapeutic for patients suffering with schizophrenia. One major hurdle with using many of the potent GCPII inhibitors that have been prepared to date are typically highly polar compounds, which causes problems because they do not then penetrate the blood–brain barrier easily.
Potential uses of NAAG peptidase inhibitors
Glutamate is the “primary excitatory neurotransmitter in the human nervous system”, participating in a multitude of brain functions. Overstimulation and -activation of glutamate receptors as well as “disturbances in the cellular mechanisms that protect against the adverse consequences of physiological glutamate receptor activation” have been known to cause neuron damage and death, which have been associated with multiple neurological diseases.
Due to the range of glutamate function and presence, it has been difficult to create glutamatergic drugs that do not negatively affect other necessary functions and cause unwanted side-effects. NAAG peptidase inhibition has offered the possibility for specific drug targeting.
Specific inhibitors
Since its promise for possible neurological disease therapy and specific drug targeting, NAAG peptidase inhibitors have been widely created and studied. A few small molecule examples are those that follow:
2-PMPA and analogues
Thiol and indole thiol derivatives
Hydroxamate derivatives
Conformationally constricted dipeptide mimetics
PBDA- and urea-based inhibitors.
Other potential therapeutic applications
Neuropathic and inflammatory pain
Pain cause by injury to CNS or PNS has been associated with increase glutamate concentration. NAAG inhibition reduced glutamate presence and could, thus, diminish pain. (Neale JH et al., 2005). Nagel et al. used the inhibitor 2-PMPA to show the analgesic effect of NAAG peptidase inhibitions. This study followed one by Chen et al., which showed similar results.
Head injury
Severe head injury (SHI) and traumatic brain injury (TBI) are widespread and have a tremendous impact. “They are the leading cause of death in children and young adults (<25 years) and account for a quarter of all deaths in the five to 15 years age group”. Following initial impact, glutamate levels rise and cause excitotoxic damage in a process that has been well characterized. With its ability to reduce glutamate levels, NAAG inhibition has shown promise in preventing neurological damage associated with SHI and TBI.
Stroke
According to the National Stroke Association, stroke is the third-leading cause of death and the leading cause of adult disability. It is thought that glutamate levels cause underlying ischemic damage during a stroke, and, thus, NAAG inhibition might be able to diminish this damage.
Schizophrenia
Schizophrenia is a mental disorder that affects 1% of people throughout the world. It can be modeled by PCP in laboratory animals, and it has been shown that mGluR agonists have reduced the effects of the drug. NAAG is such an mGluR agonist. Thus, inhibition of the enzyme that reduces NAAG concentration, NAAG peptidase, could provide a practical treatment for reduction of schizophrenic symptoms.
Diabetic neuropathy
Diabetes can lead to damaged nerves, causing loss of sensation, pain, or, if autonomic nerves are associated, damage to the circulatory, reproductive, or digestive systems, among others. Over 60% of diabetic patients are said to have some form of neuropathy, however, the severity ranges dramatically. Neuropathy not only directly causes harm and damage but also can indirectly lead to such problems as diabetic ulcerations, which in turn can lead to amputations. In fact, over half of all lower limb amputations in the United States are of patients with diabetes.
Through the use of the NAAG peptidase inhibitor 2-PMPA, NAAG cleavage was inhibited and, with it, programmed DRG neuronal cell death in the presence of high glucose levels. The researchers have proposed that the cause of this is NAAG's agonistic activity at mGluR3. In addition, NAAG also “prevented glucose-induced inhibition of neurite growth” (Berent- Spillson, et al. 2004). Overall, this makes GCPIII inhibition a clear model target for combating diabetic neuropathy.
Drug addiction
Schizophrenia, as previously described, is normally modeled in the laboratory through a PCP animal model. As GCPIII inhibition was shown to possibly limit schizophrenic behavior in this model, this suggests that GCPIII inhibition, thus, reduces the effect of PCP. In addition, the reward action of many drugs (cocaine, PCP, alcohol, nicotine, etc.) have been shown with increasing evidence to be related to glutamate levels, on which NAAG and GCPIII can have some regulatory effect.
In summary, the findings of multiple drug studies to conclude that:
NAAG/NP system might be involved in neuronal mechanisms regulating cue-induced cocaine craving, the development of cocaine seizure kindling, and management of opioid addiction and alcohol consumptive behaviour. Therefore, NP inhibitors could provide a novel therapy for such conditions.
Other diseases and disorders
NAAG inhibition has also been studied as a treatment against prostate cancer, ALS, and other neurodegenerative diseases such as Parkinson's disease and Huntington's disease.
References
External links
The MEROPS online database for peptidases and their inhibitors: M20.001
Protein Data Bank: Protein Data Bank
EC 3.4.17
Neurotransmitters
Molecular neuroscience
Zinc enzymes
Proteases
Prostate cancer | Glutamate carboxypeptidase II | [
"Chemistry"
] | 3,696 | [
"Molecular neuroscience",
"Neurochemistry",
"Neurotransmitters",
"Molecular biology"
] |
10,843,656 | https://en.wikipedia.org/wiki/New%20York%20Number%20Theory%20Seminar | The New York Number Theory Seminar is a research seminar devoted to the theory of numbers and related parts of mathematics and physics.
The seminar began in 1982 under the founding organizers Harvey Cohn, David and Gregory Chudnovsky, and Melvyn B. Nathanson. It is held at the Graduate Center, CUNY.
Overview
The New York Number Theory Seminar began in January 1982 and was originally organized by number theorists Harvey Cohn, David and Gregory Chudnovsky, and Melvyn B. Nathanson. Since the retirement of Cohn, Nathanson is the sole organizer. The seminar also organizes an annual Workshop on Combinatorial and Additive Number Theory (CANT) at the Graduate Center, CUNY.
Publications
Four volumes of the collected lecture notes of the seminar were published in the Lecture Notes in Mathematics series by Springer-Verlag. These volumes covered the seminar from 1982 to 1988. Three additional stand-alone books were published by Springer-Verlag under the title Number Theory, covering the seminar between 1989 and 2003.
External links
References
Mathematics education in the United States
City University of New York
Number theory | New York Number Theory Seminar | [
"Mathematics"
] | 222 | [
"Discrete mathematics",
"Number theory"
] |
10,843,800 | https://en.wikipedia.org/wiki/Expanded%20access | Expanded access or compassionate use is the use of an unapproved drug or medical device under special forms of investigational new drug applications (IND) or IDE application for devices, outside of a clinical trial, by people with serious or life-threatening conditions who do not meet the enrollment criteria for the clinical trial in progress.
These programs go under various names, including early access, special access, or managed access program, compassionate use, compassionate access, named-patient access, temporary authorization for use, cohort access, and pre-approval access.
In general the person and their doctor must apply for access to the investigational product, the company has to choose to cooperate, and the medicine's regulatory agency needs to agree that the risks and possible benefits of the drug or device are understood well enough to determine if putting the person at risk has sufficient potential benefit. In some countries the government will pay for the drug or device, but in many countries the person must pay for the drug or device, as well as medical services necessary to receive it.
In the US, compassionate use started with the provision of investigational medicine to certain patients in the late 1970s, and a formal program was established in 1987 in response to HIV/AIDS patients requesting access to drugs in development. An important legal case was Abigail Alliance v. von Eschenbach, in which the Abigail Alliance, a group that advocates for access to investigational drugs for people who are terminally ill, tried to establish such access as a legal right. The Supreme Court declined to hear the case, effectively upholding previous cases that have maintained that there is not a constitutional right to unapproved medical products.
Programs
regulation of access to pharmaceuticals that were not approved for marketing was handled on a country by country basis, including in the European Union, where the European Medicines Agency issued guidelines for national regulatory agencies to follow. In the US, Europe, and the EU, no company could be compelled to provide a drug or device that it was developing.
Companies sometimes provide drugs under these programs to people who were in clinical trials and who responded to the drug, after the clinical trial ends.
United States
In the US as of 2018, people could try obtain unapproved drugs or medical devices that were in development under specific conditions.
These conditions were:
The person wanting the drug or device and a licensed physician are both willing to participate.
The person's physician determines that there is no comparable or satisfactory therapy available to diagnose, monitor, or treat the patient's disease or condition.
That the probable risk to the person from the investigational product is not greater than the probable risk from the disease or condition.
The FDA determines that there is sufficient evidence of the safety and effectiveness of the investigational product to support its use in the particular circumstance;
The FDA determines that providing the investigational product will not interfere with the initiation, conduct, or completion of clinical investigations to support marketing approval;
The sponsor (generally the company developing the investigational product for commercial use) or the clinical investigator (or the patient's physician in the case of a single patient expanded access request) submits a clinical protocol (a document that describes the treatment plan for the patient) that is consistent with FDA's statute and applicable regulations for INDs or investigational device exemption applications (IDEs), describing the use of the investigational product; and
The person is unable to obtain the investigational drug or device under another IND application (for drugs), IDE application (for devices), or to participate in a clinical trial.
Drugs can be made available to individuals, small groups, or large groups.
In the US, actual provision of the drug depends on the manufacturer's willingness to provide it, as well as the person's ability to pay for it; it is the company's decision whether to require payment or to provide the drug or device for free. The manufacturer can only charge direct costs for individual INDs; it can add some but not all indirect costs for small group or larger expanded access programs. To the extent that a doctor or clinic is required for use of the drug or device, they too may require payment.
In some cases, it may be in the manufacturer's commercial interest to provide access under an EA program; this is a way, for example, for a company to make money before the drug or device is approved. Companies must provide data collected from people getting the drug or device under EA programs to the FDA annually; this data may be helpful with regard to getting the drug or device approved, or may be harmful, should unexpected adverse events occur. The manufacturer remains legally liable as well. If the manufacturer chooses to charge for the investigational product, that price influences later discussions about the price if the product is approved for marketing.
State law
, 41 states have passed right-to-try laws that permit manufacturers to provide experimental medicines to terminally ill people without US FDA authorization. Legal, medical, and bioethics scholars, including Jonathan Darrow and Arthur Caplan, have argued that these state laws have little practical significance because people can already obtain pre-approval access through the FDA's expanded access program, and because the FDA is generally not the limiting factor in obtaining pre-approval access.
Europe
In Europe, the European Medicines Agency issued guidelines that members may follow. Each country has its own regulations, and they vary. In the UK, for example, the program is called "early access to medicine scheme" or EAMS and was established in 2014. If a company that wants to provide a drug under EAMS, it must submit its Phase I data to the Medicines and Healthcare products Regulatory Agency and apply for what is called a "promising innovative medicine" (PIM) designation. If that designation is approved, the data is reviewed, if that review is positive, the National Health Service is obligated to pay for people who fit the criteria to have access to the drug. As of 2016, governments also paid for early access to drugs in Austria, Germany, Greece, and Spain. Since 2021, France has a system of early and expanded access separated in two systems: AAC and AAP.
Companies sometimes make use of expanded programs in Europe even after they receive EMA approval to market a drug, because drugs also must go through regulatory processes in each member state, and in some countries this process can take nearly a year; companies can start making sales earlier under these programs.
Philippines
In the Philippines, the usage of unregistered drugs may be allowed through a doctor, a specialist, or health institution or society obtaining a specific compassionate use permit (CSP) from the country's Food and Drug Administration for the treatment of their terminally or seriously ill patients. The issuance of CSP is stated under Department of Health Administrative Order No. 4 of 1992.
Those seeking CSP are required to provide the following information; estimated amount of the unregistered drug the patient, the "licensed drug/device establishment through which the unregistered drug may be procured", and "the names and address of the specialists qualified and authorized to use the product." A CSP may also be obtained for processed medical cannabis despite cannabis in general being illegal in the Philippines.
History
In the US, one of the earliest expanded access programs was a compassionate use IND that was established in 1978, which allowed a limited number of people to use medical cannabis grown at the University of Mississippi, under the direction of Marijuana Research Project Director Dr. Mahmoud ElSohly. It is administered by the National Institute on Drug Abuse.
The program was started after Robert C. Randall brought a lawsuit (Randall v. U.S) against the FDA, the Drug Enforcement Administration, the National Institute on Drug Abuse, the Department of Justice, and the Department of Health, Education & Welfare. Randall, who had glaucoma, had successfully used the Common Law doctrine of necessity to argue against criminal charges of marijuana cultivation that had been brought against him, because his use of cannabis was deemed a medical necessity (U.S. v. Randall). On November 24, 1976, federal Judge James Washington ruled in his favor.
The settlement in Randall v. U.S. became the legal basis for the FDA's compassionate IND program. People were only allowed to use cannabis under the program who had certain conditions, like glaucoma, known to be alleviated with cannabis. The scope was later expanded to include people with AIDS in the mid-1980s. At its peak, fifteen people received the drug. 43 people were approved for the program, but 28 of the people whose doctors completed the necessary paperwork never received any cannabis. The program stopped accepting new people in 1992 after public health authorities concluded there was no scientific value to it, and due to President George H. W. Bush administration's policies. As of 2011, four people continued to receive cannabis from the government under the program.
The closure of the program during the height of the AIDS epidemic led to the formation of the medical cannabis movement in the United States, a movement which initially sought to provide cannabis for treating anorexia and wasting syndrome in people with AIDS.
In November 2001 the Abigail Alliance for Better Access to Developmental Drugs was established by Frank Burroughs in memory of his daughter, Abigail. The Alliance seeks broader availability of investigational drugs on behalf of people with terminal illnesses. It is best known for a legal case, which it lost, Abigail Alliance v. von Eschenbach, in which it was represented by the Washington Legal Foundation. On August 7, 2007, in an 8–2 ruling, the U.S. Court of Appeals for the District of Columbia Circuit reversed an earlier ruling in favor of the Alliance. In 2008, the Supreme Court of the United States declined to hear their appeal. This decision left standing the appellate court decision that people who are terminal ill patients have no legal right to demand "a potentially toxic drug with no proven therapeutic benefit".
In March 2014, Josh Hardy, a 7-year-old boy from Virginia, made national headlines that sparked a conversation on pediatric access to investigational drugs when his family's request for brincidofovir was declined by the drug manufacturer, Chimerix. The company reversed its decision after pressure from cancer advocacy organizations, and Josh received the drug that saved his life. Hardy later passed away in September 2016 due to complications related to his underlying cancer diagnosis. In 2016 Kids v Cancer, a pediatric cancer advocacy organization, launched the Compassionate Use Navigator to assist physicians and guide families about the application process. Since then, FDA simplified the application process, but stressed that it cannot require a manufacturer to provide a product. FDA receives about 1,500 expanded access requests per year and authorizes 99% of it.
See also
Orphan drug
Right-to-try law
Emergency Use Authorization
References
Citations
External links
Europeans Medicines Agency
Food and Drug Administration U.S
FDA Personal Importation and EMA Named Patient Import
The Socialmedwork as a named patient import Provider
myTomorrows Expanded Access as an Expanded Access Provider
Sources
Clinical pharmacology
Clinical research | Expanded access | [
"Chemistry"
] | 2,240 | [
"Pharmacology",
"Clinical pharmacology"
] |
10,844,157 | https://en.wikipedia.org/wiki/Parasite%20Rex | Parasite Rex: Inside the Bizarre World of Nature's Most Dangerous Creatures is a nonfiction book by Carl Zimmer that was published by Free Press in 2000. The book discusses the history of parasites on Earth and how the field and study of parasitology formed, along with a look at the most dangerous parasites ever found in nature. A special paperback edition was released in March 2011 for the tenth anniversary of the book's publishing, including a new epilogue written by Zimmer. Signed bookplates were also given to fans that sent in a photo of themselves with a copy of the special edition.
The cover of Parasite Rex includes a scanning electron microscope image of a tick as the focus, along with illustrations in the centerfold of parasites and topics discussed in the book.
Content
The book begins by discussing the history of parasites in human knowledge, from the earliest writings about them in ancient cultures, up through modern times. The focus comes to rest extensively on the views and experiments conducted by scientists in the 17th, 18th, and 19th centuries, such as those done by Antonie van Leeuwenhoek, Japetus Steenstrup, Friedrich Küchenmeister, and Ray Lankester. Among them, Leeuwenhoek was the first to ever physically view cells through a microscope, Steenstrup was the first to explain and confirm the multiple stages and life cycles of parasites that are different from most other living organisms, and Küchenmeister, through his religious beliefs and his views on every creature having a place in the natural order, denied the ideas of his time and proved that all parasites are a part of active evolutionary niches and not biological dead ends by conducting morally ambiguous experiments on prisoners. Lankester is given a specific focus and repeated discussion throughout the book due to his belief that parasites are examples of degenerative evolution, especially in regards to Sacculina, and Zimmer's repeated refutation of this idea.
Several chapters are taken to discuss various types of parasites and how they infect and control their hosts, along with the biochemistry involved in their take-over or evasion of their host's immune system, eventually leading to their dispersal into their next form and life cycle. An extended time is also given on the workings of immunology and how the immune systems of living beings respond to parasite infection, along with the methods that bodily functions use to counteract and potentially kill invading microorganisms. Woven into this discussion are several specific sites that Zimmer visited during his writing of Parasite Rex and the scientists he worked with to understand different biosystems and all the parasites that live within them, including human sleeping sickness infections in Sudan from the tsetse fly, the parasites of frogs in Costa Rica, primarily showcased by filarial worms that infect humans and a variety of species, and the USDA National Parasite Collection based out of Maryland.
The final chapters focus on an overall effect parasites have had on the evolution of life and the theory that it is due to parasitic infection that sexual reproduction evolved to become dominant, in contrast to previous asexual reproduction methods, due to the increased genetic variety and thus potential parasitic resistance that this would confer. This research was showcased by W. D. Hamilton and his theories on the evolution of sex, along with the Red Queen hypothesis and the idea of an evolutionary arms race between parasites and their hosts. Zimmer then discusses a final time the wide variety of parasites that evolved to have humans as their primary hosts and our attempts through scientific advancement to eradicate them. The closing chapter considers the positive benefits of parasites and how humans have used them to improve agriculture and medical technology, but also how ill-considered usage of parasites could also destroy various habitats by having them act as invasive species. In the end, Zimmer ponders whether humanity counts as a parasite on the planet and what the effects of this relationship could be.
Style and tone
In a review for Science, Albert O. Bush pointed out how Zimmer creates a writing style that is written with "clarity, conviction, and seemingly without prejudice" and that while the "purist will find the odd mistakes, oversights, and minor errors of fact", these are "insignificant" and do not remove from Parasite Rex'''s "overall quality or, more importantly, its focus and take-home message."
Reception The New York Times' Kevin Padian praised the book and Zimmer's writing, saying that it showcases him as "fine a science essayist as we have" and that the importance of this book rests "not only in its accessible presentation of the new science of evolutionary parasitology but in its thoughtful treatment of the global strategies and policies that scientists, health workers and governments will have to consider in order to manage parasites in the future". Publishers Weekly called the book a "exemplary work of popular science" and one of the "most fascinating works" of its kind, while also being "its most disgusting". Margaret Henderson, writing for the Library Journal, recommended the book for placement in all libraries, saying that the book "makes parasitology interesting and accessible to anyone". Writing in the Quarterly Review of Biology, May Berenbaum describes Parasite Rex as a "remarkable book" that is "unique in its focus and is extremely readable" and earns the reviewer's "respect and recommendation" for being able to discuss the life cycles of lancet flukes and the Red Queen hypothesis properly in a single book. Joe Eaton in the Whole Earth Review categorized Parasite Rex as "one of those books that change the way you see the world" due to how it shows that ecosystems are largely made up of the parasites that the individual organisms carry. A review in The American Biology Teacher by Donald A. Lawrence labeled the book as a "splendid overview of current knowledge about parasites" and praised the extensive Notes, Literature Cited, and Index sections. The newsletter editor for the American Society of Parasitologists, Scott Lyell Gardner, congratulated the book for bringing the field of parasitology into the public view, saying that how Zimmer "presents parasites in the “ugh” and “oooh” mode, in addition to trying to show how parasitologists actually ply our trade" helps to provide interest into the subject. BlueSci writer Harriet Allison summed up the book as one where Zimmer "manages to weave just enough easily understandable science into each chapter in order to create an engrossing and squirm-inducing story that will have you hooked until the end". Kirkus Reviews stated its acclaim for the "vivid detail" given to the lifestyles of parasites, calling the book an "eye-opening perspective on biology, ecology, and medicine" and "well worth reading".
See also
Microcosm: E. coli and the New Science of Life''
Veterinary parasitology
Conservation biology of parasites
References
External links
Parasite Rex on Carl Zimmer's website
Parasite Rex on the Simon & Schuster, Publisher website
2000 non-fiction books
Biology books
Ecology books
Parasitology literature
Biochemistry literature | Parasite Rex | [
"Chemistry",
"Biology"
] | 1,442 | [
"Biochemistry",
"Biochemistry literature"
] |
10,844,329 | https://en.wikipedia.org/wiki/Exploration%20of%20Saturn | The exploration of Saturn has been solely performed by crewless probes. Three missions were flybys, which formed an extended foundation of knowledge about the system. The Cassini–Huygens spacecraft, launched in 1997, was in orbit from 2004 to 2017.
Missions
A list of previous and upcoming missions to the outer Solar System (including Saturn) can be found at the List of missions to the outer planets article.
Flybys
Pioneer 11 flyby
Saturn was first visited by Pioneer 11 in September 1979. It flew within of the top of the planet's cloud layer. Low-resolution images were acquired of the planet and a few of its moons; the resolution of the images was not good enough to discern surface features. The spacecraft also studied the rings; among the discoveries were the thin F-ring and the fact that dark gaps in the rings are bright when viewed towards the Sun, or in other words, they are not empty of material. Pioneer 11 also measured the temperature of Titan at 250 K.
Voyagers
In November 1980, the Voyager 1 probe visited the Saturn system. It sent back the first high-resolution images of the planet, rings, and satellites. Surface features of various moons were seen for the first time. Because of the earlier discovery of a thick atmosphere on Titan, the Voyager controllers at the Jet Propulsion Laboratory elected for Voyager 1 to make a close approach of Titan. This greatly increased knowledge of the atmosphere of the moon, but also proved that Titan's atmosphere is impenetrable in visible wavelengths, so no surface details were seen. The flyby also changed the spacecraft's trajectory out from the plane of the Solar System which prevented Voyager 1 from completing the Planetary Grand Tour of Uranus, Neptune and Pluto.
Almost a year later, in August 1981, Voyager 2 continued the study of the Saturn system. More close-up images of Saturn's moons were acquired, as well as evidence of changes in the rings. Voyager 2 probed Saturn's upper atmosphere with its radar, to measure temperature and density profiles. Voyager 2 found that at the highest levels (7 kilopascals pressure) Saturn's temperature was 70 K (−203 °C) (i.e. 70 degrees above absolute zero), while at the deepest levels measured (120 kilopascals) the temperature increased to 143 K (−130 °C). The north pole was found to be 10 K cooler, although this may be seasonal. Unfortunately, during the flyby, the probe's turnable camera platform stuck for a couple of days and some planned imaging was lost. Saturn's gravity was used to direct the spacecraft's trajectory towards Uranus.
The probes discovered and confirmed several new satellites orbiting near or within the planet's rings. They also discovered the small Maxwell and Keeler gaps in the rings.
Cassini orbiter
On July 1, 2004, the Cassini–Huygens spacecraft performed the SOI (Saturn Orbit Insertion) maneuver and entered into orbit around Saturn. Before the SOI, Cassini had already studied the system extensively. In June 2004, it had conducted a close flyby of Phoebe, sending back high-resolution images and data.
The orbiter completed two Titan flybys before releasing the Huygens probe on December 25, 2004. Huygens descended onto the surface of Titan on January 14, 2005, sending a flood of data during the atmospheric descent and after the landing. During 2005 Cassini conducted multiple flybys of Titan and icy satellites.
On March 10, 2006, NASA reported that the Cassini probe found evidence of liquid water reservoirs that erupt in geysers on Saturn's moon Enceladus.
On September 20, 2006, a Cassini probe photograph revealed a previously undiscovered planetary ring, outside the brighter main rings of Saturn and inside the G and E rings.
In July 2006, Cassini saw the first proof of hydrocarbon lakes near Titan's north pole, which was confirmed in January 2007. In March 2007, additional images near Titan's north pole discovered hydrocarbon "seas", the largest of which is almost the size of the Caspian Sea.
In 2009, the probe discovered and confirmed four new satellites. Its primary mission ended in 2008, when the spacecraft completed 74 orbits around the planet. In 2010, the probe began its first extended mission, the Cassini Equinox Mission. The Cassini Solstice Mission, the second mission extension, lasted through September 2017. The mission ended on September 15, 2017, after a planned atmospheric entry into the planet Saturn.
Future missions
China's CNSA two Interstellar Express spacecraft expected to launch in 2024 may include a flyby of Saturn. NASA's Dragonfly spacecraft will launch in 2028 to visit the Saturn system, with the objective of landing on the moon Titan.
Proposed missions
The Titan Saturn System Mission (TSSM) was a joint NASA/ESA proposal for an exploration of Saturn and its moons Titan and Enceladus, where many complex phenomena have been revealed by the recent Cassini–Huygens mission. TSSM was competing against the Europa Jupiter System Mission proposal for funding. In February 2009 it was announced that ESA/NASA had given the EJSM mission priority ahead of TSSM, although TSSM will continue to be studied for a later launch date. The Titan Saturn System Mission (TSSM) was created by the merging of the ESA's Titan and Enceladus Mission (TandEM) with NASA's Titan Explorer 2007 flagship study.
Other proposed missions to the Saturn system were:
2010 JPL: Journey to Enceladus and Titan (JET)
2011 Titan Mare Explorer (TiME); an aquatic lander that would explore the methane lakes of the moon Titan. This mission was given US$3 million in May 2011 to develop a detailed concept study as a part of the NASA Discovery program.
2012 DLR: Enceladus Explorer (EnEx), a lander with an ice mole.
2012 JPL: Life Investigation For Enceladus (LIFE) a sample-return.
2015 JPL: Enceladus Life Finder (ELF)
2020 Applied Physics Laboratory: Enceladus Orbilander
See also
Exploration of Mercury
Exploration of Venus
Exploration of Mars
Exploration of Jupiter
Exploration of Uranus
Exploration of Neptune
References
Further reading
External links
NASA's Cassini mission to Saturn
Saturn
Spaceflight
Discovery and exploration of the Solar System
Solar System | Exploration of Saturn | [
"Astronomy"
] | 1,315 | [
"Outer space",
"History of astronomy",
"Spaceflight",
"Solar System",
"Discovery and exploration of the Solar System"
] |
10,844,989 | https://en.wikipedia.org/wiki/3-Methylfentanyl | 3-Methylfentanyl (3-MF, mefentanyl) is an opioid analgesic that is an analog of fentanyl. 3-Methylfentanyl is one of the most potent opioids, estimated to be between 400 and 6000 times stronger than morphine, depending on which isomer is used (with the cis isomers being the more potent ones).
Overview and history
was first discovered in 1974 and subsequently appeared on the street as an alternative to the clandestinely produced fentanyl analog α-methylfentanyl. However, it quickly became apparent that was much more potent than α-methylfentanyl, and correspondingly more dangerous.
While was initially sold on the black market for only a short time between 1984 and 1985, its high potency made it an attractive target to clandestine drug producers, as racemic is 10–15 times more potent than fentanyl, and so correspondingly larger amounts of cut product for street sales can be produced for an equivalent amount of effort as for producing fentanyl itself; one gram of might be sufficient to produce several thousand dosage units once diluted for sale. has thus reappeared several times, at various places around the world.
The only country in the world with significant (200+ deaths a year, more than 10,000 addicts) abuse of this chemical is Estonia, where a dose of costs 10 €, and other opiates are not generally available since the end of the 2000s. Approximately 1100 deaths from fentanyl and abuse were recorded in Estonia between 2005–2013, compared to approximately 450 deaths in Sweden, Germany, UK, Finland and Greece combined during the same period.
Other opioid analogs even more potent still than are known, such as carfentanil and ohmefentanyl, but these are significantly more difficult to manufacture than . Since 2016 fentanyl seizures in Estonia contains mostly carfentanil or cyclopropylfentanyl.
has similar effects to fentanyl, but is far more potent due to increased binding affinity to its target site. Since fentanyl itself is already highly potent, is extremely dangerous when used recreationally, and has resulted in many deaths among recreational opioid users ingesting the drug. Side effects of fentanyl analogs are similar to those of fentanyl itself, which include itching, nausea and potentially serious respiratory depression, which can be life-threatening. Fentanyl analogs have killed hundreds of people throughout Europe and the former Soviet republics since the most recent resurgence in use began in Estonia in the early 2000s, and novel derivatives continue to appear.
Use as chemical weapon
3-Methylfentanyl was also reported by media as the identity of the anaesthetic "gas" Kolokol-1 delivered as an aerosol during the Moscow theater hostage crisis in 2002 in which many hostages died from accidental overdoses, 3-methylfentanyl was later ruled out as the primary agent used. The opiate antidote naloxone was on-hand to treat the victims of the crisis, but, whether due to their incarceration, lack of food, or water, or sleep, or due to the novel nature of the still-unconfirmed compound used, acute symptoms continued to develop, resulting in many fatalities despite the administration of naloxone.
Synthesis
A number of methods for synthesis have been published. The most recent is probably the method posted by the Serbian chemical society (2004).
There is another method, though, for constructing the N-Benzyl-3-methyl-4-piperidone in a 2-stage Michael reaction, followed by Dieckmann cyclization as per usual.
See also
3-Methylbutyrfentanyl
4-Fluorofentanyl
α-Methylfentanyl
Acetylfentanyl
Butyrfentanyl
List of fentanyl analogues
References
Synthetic opioids
Piperidines
Propionamides
Anilides
Mu-opioid receptor agonists
Designer drugs
Chemical weapons | 3-Methylfentanyl | [
"Chemistry",
"Biology"
] | 828 | [
"Biochemistry",
"Chemical accident",
"Chemical weapons"
] |
10,845,121 | https://en.wikipedia.org/wiki/Builder%27s%20Old%20Measurement | Builder's Old Measurement (BOM, bm, OM, and o.m.) is the method used in England from approximately 1650 to 1849 for calculating the cargo capacity of a ship. It is a volumetric measurement of cubic capacity. It estimated the tonnage of a ship based on length and maximum beam. It is expressed in "tons burden" (, ), and abbreviated "tons bm".
The formula is:
where:
Length is the length, in feet, from the stem to the sternpost;
Beam is the maximum beam, in feet.
The Builder's Old Measurement formula remained in effect until the advent of steam propulsion. Steamships required a different method of estimating tonnage, because the ratio of length to beam was larger and a significant volume of internal space was used for boilers and machinery. In 1849, the Moorsom System was created in the United Kingdom. The Moorsom system calculates the cargo-carrying capacity in cubic feet, another method of volumetric measurement. The capacity in cubic feet is then divided by 100 cubic feet of capacity per gross ton, resulting in a tonnage expressed in tons.
History and derivation
King Edward I levied the first tax on the hire of ships in England in 1303 based on tons burthen. Later, King Edward III levied a tax of 3 shillings on each "tun" of imported wine, roughly . At that time a "tun" was a wine container of 252 wine gallons, approx weighing about , a weight known today as a long ton or imperial ton. In order to estimate the capacity of a ship in terms of 'tun' for tax purposes, an early formula used in England was:
where:
Length is the length (undefined), in feet
Beam is the beam, in feet.
Depth is the depth of the hold, in feet below the main deck.
The numerator yields the ship's volume expressed in cubic feet.
If a "tun" is deemed to be equivalent to 100 cubic feet, then the tonnage is simply the number of such 100 cubic feet 'tun' units of volume.
100 the divisor is unitless, so tonnage would be expressed in 'ft3 of tun'.
In 1678 Thames shipbuilders used a method assuming that a ship's burden would be 3/5 of its displacement. Since tonnage is calculated by multiplying length × beam × draft × block coefficient, all divided by 35 ft3 per ton of seawater, the resulting formula would be:
where:
Draft is estimated to be half of the beam.
Block coefficient is based on an assumed average of 0.62.
35 ft3 is the volume of one ton of sea water.
Or by solving :
In 1694 a new British law required that tonnage for tax purposes be calculated according to a similar formula:
This formula remained in effect until the Builder's Old Measurement rule (above) was put into use in 1720, and then mandated by Act of Parliament in 1773.
Depth
Depth to deck
The height from the underside of the hull, excluding the keel itself, at the ship's midpoint, to the top of the uppermost full length deck.
Depth in hold
Interior space; The height from the lowest part of the hull inside the ship, at its midpoint, to the ceiling that is made up of the uppermost full length deck. For old warships it is to the ceiling that is made up of the lowermost full length deck.
Main deck
Main deck, that is used in context of depth measurement, is usually defined as the uppermost full length deck. For the 16th century ship Mary Rose, main deck is the second uppermost full length deck. In a calculation of the tonnage of Mary Rose the draft was used instead of the depth.
American tons burthen
The British took the length measurement from the outside of the stem to the outside of the sternpost, whereas the Americans measured from inside the posts. The British measured breadth from outside the planks, whereas the Americans measured the breadth from inside the planks. Lastly, the British divided by 94, whereas the Americans divided by 95.
The upshot was that American calculations gave a lower number than the British ones. The British measure yields values about 6% greater than the American. For instance, when the British measured the captured , their calculations gave her a burthen of 1533 tons, whereas the American calculations gave the burthen as 1444 tons.
The US system was in use from 1789 until 1864, when a modified version of the Moorsom System was adopted.
See also
Thames Measurement
References
External links
"Concerning Measuring of Ships", The Sea-Man's Vade Mecum, London, 1707. pp 127–131.
"Of Finding the Tonnage or Burthen of Ships, &c.", David Steel, The Shipwright's Vade-Mecum, London, 1805. pp. 249–251.
"Burthen", or "Burden", William Falconer's Dictionary of the Marine, London, 1780, page 56
Mass
Nautical terminology
Sailing rules and handicapping
Ship measurements
Volume | Builder's Old Measurement | [
"Physics",
"Mathematics"
] | 1,039 | [
"Scalar physical quantities",
"Physical quantities",
"Quantity",
"Mass",
"Size",
"Extensive quantities",
"Volume",
"Wikipedia categories named after physical quantities",
"Matter"
] |
10,845,339 | https://en.wikipedia.org/wiki/American%20Society%20of%20Safety%20Professionals | The American Society of Safety Professionals (ASSP), formerly known as American Society of Safety Engineers (ASSE), is a global organization of occupational safety and health (OSH) professional members who manage, supervise, research and consult on work-related OSH concerns across all industries. Society members use risk-based approaches to prevent workplace fatalities, injuries and illnesses.
The organization was founded on 25 March 1911 in the wake of the Triangle Shirtwaist Factory fire, after lack of safety measures caused the death of 146 garment workers.
ASSP offers continuing education to OSH professionals, participates in developing industry standards, pursues initiatives that aim to build the reputation of the OSH profession, and provides access to various member communities. The organization has alliances with federal agencies such as Occupational Safety and Health Administration (OSHA) and National Institute for Occupational Safety and Health (NIOSH). ASSP also works with the Accreditation Board for Engineering & Technology (ABET) to develop accreditation standards for OSH-related degree programs and has worked with the International Network of Safety and Health Practitioner Organizations (INSHPO) to develop a professional capability framework for OSH professionals.
Organization
The American Society of Safety Professionals has 151 local chapters, 40 sections and 65 student sections located across 75 countries. Members live in regions including the Americas, Europe, the Middle East, Africa, Asia and Australia.
The ASSP has specialty communities that focus on particular industries or fields of professional practice, including academia, construction, consulting, engineering, environment, ergonomics, fire protection, healthcare, industrial hygiene, international, management, manufacturing, oil, gas, mining and minerals, public sector, risk management/insurance and transportation. The organization also has four common interest groups – Blacks in Safety Excellence (BISE), Hispanic Safety Professionals, Women in Safety Excellence (WISE) and Young Professionals in OSH.
Consensus Standards
ASSP is secretariat for several American National Standards Institute (ANSI) committees and administrator for the United States technical advisory groups (TAG) to the International Organization for Standardization (ISO) on fall protection, risk management and occupational health and safety management systems. Members represent the organization on a wide range of safety and health committees affiliated with standards-development organizations such as National Fire Protection Association (NFPA), International Safety Equipment Association (ISEA) and ASTM International.
The committees develop and maintain the standards, ensure that the revision process is timely and in accordance with ANSI procedures, and publish the final product. ASSP is secretariat or administrator for the U.S. TAG for the following standards:
Confined Spaces (Z117)
Construction and Demolition Operations (A10)
Fall Protection and Fall Restraint (Z359)
Fleet Safety (Z15)
Hydrogen Sulfide Training (Z390)
Lockout/Tagout and Alternative Methods (Z244)
Occupational Health and Safety Management Systems (Z10, ISO 45001)
OSH Training (Z490)
Prevention Through Design (Z590.3)
Risk Management (ISO 31000/ANSI/ASSP Z690)
Scope and Functions of the Professional Safety Position (Z590.2)
Ventilation Systems (Z9)
Walking/Working Surfaces (A1264)
Center for Safety and Health Sustainability
The Center for Safety and Health Sustainability is a global collaborative effort among ASSP, the American Industrial Hygiene Association (AIHA), and the United Kingdom’s Institution of Occupational Safety and Health (IOSH). Its work focuses on improving corporate recognition of employee safety, health, and well-being as a sustainable business practice.
ASSP Foundation
The American Society of Safety Professionals Foundation, established by the ASSP, generates funding and provides resources for research opportunities, educational advancement and leadership development to advance the OSH profession. As a 501(c)(3) organization, contributions to the Foundation are generally considered charitable contributions under IRC Section 170 and are tax deductible as provided by law.
See also
Loss-control consultant
American Society of Mechanical Engineers
ASSE-MEC
References
External links
American Society of Safety Professionals – official website
Occupational Safety and Health Administration official website
American Society of Safety Professionals Foundation official website
Engineering societies based in the United States
Safety engineering organizations
Triangle Shirtwaist Factory fire
Occupational safety and health organizations
Organizations established in 1911
1911 establishments in the United States | American Society of Safety Professionals | [
"Engineering"
] | 872 | [
"Safety engineering organizations",
"Safety engineering"
] |
10,846,707 | https://en.wikipedia.org/wiki/Hexazine | Hexazine (also known as hexaazabenzene) is a hypothetical allotrope of nitrogen composed of 6 nitrogen atoms arranged in a ring-like structure analogous to that of benzene. As a neutrally charged species, it would be the final member of the azabenzene (azine) series, in which all of the methine groups of the benzene molecule have been replaced with nitrogen atoms. The two last members of this series, hexazine and pentazine, have not been observed, although all other members of the azine series have (such as pyridine, pyrimidine, pyridazine, pyrazine, triazines, and tetrazines).
While a neutrally charged hexazine species has not yet been synthesized, two negatively charged variants, [N6]2- and [N6]4-, have been produced in potassium-nitrogen compounds under very high pressures (> 40 GPa) and temperatures (> 2000 K). In particular, [N6]4- is aromatic, respecting Hückel's rule, while [N6]2- is anti-aromatic.
Stability
The hexazine molecule bears a structural similarity to the very stable benzene molecule. Like benzene, it has been calculated that hexazine is likely an aromatic molecule. Despite this, it has yet to be synthesized. Additionally, it has been predicted computationally that the hexazine molecule is highly unstable, possibly due to the lone pairs on the nitrogen atoms, which may repel each other electrostatically and/or cause electron-donation to sigma antibonding orbitals. A figure-8-shaped isomer is predicted to be metastable.
See also
6-membered rings with other numbers of nitrogen atoms: pyridines, diazines, triazines, tetrazines, and (like hexazine, theoretical) pentazines
Azide
Pentazole (HN5)
Other molecular allotropes of nitrogen: tetranitrogen (N4), octaazacubane (N8)
Other inorganic benzene analogues: borazine, hexaphosphabenzene
References
Further reading
External links
Azines (heterocycles)
Aromatic compounds
Hypothetical chemical compounds
Allotropes of nitrogen
Six-membered rings | Hexazine | [
"Chemistry"
] | 491 | [
"Allotropes",
"Allotropes of nitrogen",
"Aromatic compounds",
"Hypotheses in chemistry",
"Organic compounds",
"Theoretical chemistry",
"Hypothetical chemical compounds"
] |
10,846,971 | https://en.wikipedia.org/wiki/B1%20cell | B1 cells are a sub-class of B cell lymphocytes that are involved in the humoral immune response. They are not part of the adaptive immune system, as they have no memory, but otherwise, B1 cells perform many of the same roles as other B cells: making antibodies against antigens and acting as antigen-presenting cells. These B1 cells are commonly found in peripheral sites, but less commonly found in the blood. These cells are involved in antibody response during an infection or vaccination.
There are two types of B1 cells subsets, B1a cells and B1b cells. B1b cells have been shown to be capable of memory responses. B1b cells also can recognize protective antigens in bacteria, which is unique because they are targeting something internal.
Origin
B1 cells are first produced in the fetus and most B1 cells undergo self-renewal in the periphery, unlike conventional B cells (B2 cells) that are produced after birth and replaced in the bone marrow.
Types
Human B1 cells have been found to have marker profile of CD20+CD27+CD43+CD70- and could either be CD5+ or CD5-, which has been debated since. CD5-CD72 is thought to mediate B cell-B cell interaction. What differentiates B1 cells from other B cells is the variable existence of CD5, CD86, IgM and IgD. B-1 B cells, in the mouse, can be further subdivided into B-1a (CD5+) and B-1b (CD5−) subtypes. Unlike B-1a B cells, the B-1b subtype can be generated from precursors in the adult bone marrow. The B1a and B1b precursors have been reported to differ in the expression levels of CD138.
Compared to B1a cells, B1b cells seem to recognize more types of antigens including intracellular antigens. Previously, B1b cell antigen recognition was thought to be random; however, recent research indicated that B1b cells specifically target a variety of protective antigens, also called conserved factors, over other types antigens.
Recent functional studies indicate a further subdivision of labor assigning B1a cells as the producers of natural serum antibody (7). In contrast, B1b cells appear to be the primary source of dynamic T cell independent (TI) antibody production and long-term protection after bacterial infection such as Borrelia hermsii and Streptococcus pneumoniae. These studies indicate preexisting subset differences in B-cell receptor (BCR) specificity and antigen-driven B cell fate that remain important unresolved features of the system.
B1a derived cells have a subset named innate response activator(IRA) B cells. IRA B cells produce GM-CSF and IL-3. In atherosclerosis, they accumulate in spleen. This results in extramedullary hematopoiesis and activating dendritic cell.
Role in immune response
B1b cells are the most common B cells involved in antibody response during an infection or vaccination. This is because they can respond without receiving an activation signal from a T Helper cell.
B1 cells express IgM in greater quantities than IgG and its receptors show polyspecificity, meaning that they have low affinities for many different antigens. These polyspecific immunoglobulins often have a preference for other immunoglobulins, self antigens and common bacterial polysaccharides. B1 cells are present in low numbers in the lymph nodes and spleen and are instead found predominantly in the peritoneal and pleural cavities. B1 cells generate diversity mainly via recombinatorial recombination (there is a preferential recombination between D-proximal VH gene segments).
B1 cells characteristically express high levels of surface IgM (sIgM), demonstrable CD11b, and low levels of surface IgD (sIgD), CD21, CD23, and the B cell isoform of CD45R (B220). In adult mice, B1 cells constitute a minor fraction of the spleen and secondary lymphoid tissues but are enriched in the pleural and peritoneal cavities., B1 cells were shown to arise from precursors in the fetal liver and neonatal but not adult bone marrow and constitute the earliest wave of mature peripheral B cells.
B1 cells express a separable BCR repertoire. Sequence analysis indicates antibodies with restricted sets of V region genes and an increased usage of λ light chains. B1 cells sequences also show no evidence for somatic hypermutation (SHM), and few non-templated nucleotide (N) sequence insertions, a pattern typical of neonatal B cells. Efficient B1 B cell development appears to be dependent on positive regulators of BCR signaling and the loss of negative regulators promotes greater accumulation of B1 B cells. Hence, there appears to be a role for self or foreign antigen in shaping the repertoire of the B-1 B cell compartment.
B1 cells self-renew and spontaneously secrete IgM and IgG3 serum antibodies. These natural serum antibodies display extensive polyreactivity, demonstrable self-reactivity and bind to many common pathogen-associated carbohydrates. Natural serum antibodies play an important early role in the immune response to many bacteria and viruses but require complement fixation for effective antigen clearance. Innate sensing mechanisms can rapidly mobilize B1 cells regardless of specificity, highlighting the innate-like activity of this separate B cell compartment.
B1b cells are known to be able to induce some type of memory, but their role in memory cells is unknown and may follow an untraditional route.
B1b cells have effective and long-lasting responses to Borrelia hermsii, Streptococcus pneumoniae, Salmonella Enterica, Salmonella Typhi and Enterobacter cloacae bacteria.
Laboratory isolation
In research laboratories, B1 cells can be easily isolated from a mouse by injecting cell medium or PBS into the peritoneal cavity of the mouse and then draining it off via a technique mirroring diagnostic peritoneal lavage. Cells can be identified and placed into two categories "B1a" or B1b" using flow cytometry looking for surface expression of CD19, B220, and CD5. B1a expresses high CD5 level, while B1b expresses low CD5 to almost-absent levels; both are CD19+ and B220low/-.
References
B cells
Lymphocytes
Cells
Human cells
Immunology
Immune system | B1 cell | [
"Biology"
] | 1,377 | [
"Organ systems",
"Immunology",
"Immune system"
] |
10,847,056 | https://en.wikipedia.org/wiki/Lithium%20triethylborohydride | Lithium triethylborohydride is the organoboron compound with the formula LiEt3BH. Commonly referred to as LiTEBH or Superhydride, it is a powerful reducing agent used in organometallic and organic chemistry. It is a colorless or white liquid but is typically marketed and used as a THF solution. The related reducing agent sodium triethylborohydride is commercially available as toluene solutions.
LiBHEt3 is a stronger reducing agent than lithium borohydride and lithium aluminium hydride.
Preparation
LiBHEt3 is prepared by the reaction of lithium hydride (LiH) and triethylborane (Et3B) in tetrahydrofuran (THF):
LiH + Et3B → LiEt3BH
The resulting THF complex is stable indefinitely in the absence of moisture and air.
Reactions
Alkyl halides are reduced to the alkanes by LiBHEt3.
LiBHEt3 reduces a wide range of functional groups, but so do many other hydride reagents. Instead, LiBHEt3 is reserved for difficult substrates, such as sterically hindered carbonyls, as illustrated by reduction of 2,2,4,4-tetramethyl-3-pentanone. Otherwise, it reduces acid anhydrides to alcohols and the carboxylic acid, not to the diol. Similarly lactones reduce to diols. α,β-Enones undergo 1,4-addition to give lithium enolates. Disulfides reduce to thiols (via thiolates). LiBHEt3 deprotonates carboxylic acids, but does not reduce the resulting lithium carboxylates. For similar reasons, epoxides undergo ring-opening upon treatment with LiBHEt3 to give the alcohol. With unsymmetrical epoxides, the reaction can proceed with high regio- and stereo- selectivity, favoring attack at the least hindered position:
Acetals and ketals are not reduced by LiBHEt3. It can be used in the reductive cleavage of mesylates and tosylates. LiBHEt3 can selectively deprotect tertiary N-acyl groups without affecting secondary amide functionality. It has also been shown to reduce aromatic esters to the corresponding alcohols as shown in eq 6 and 7.
LiBHEt3 also reduces pyridine and isoquinolines to piperidines and tetrahydroisoquinolines respectively.
The reduction of β-hydroxysulfinyl imines with catecholborane and LiBHEt3 produces anti-1,3-amino alcohols shown in (8).
Precautions
LiBHEt3 reacts exothermically, potentially violently, with water, alcohols, and acids, releasing hydrogen and the pyrophoric triethylborane.
References
Borohydrides
Lithium compounds
Reducing agents
Organoboron compounds
Ethyl compounds
Hydrides | Lithium triethylborohydride | [
"Chemistry"
] | 643 | [
"Redox",
"Reducing agents"
] |
14,476,022 | https://en.wikipedia.org/wiki/Pfeiffer%20effect | The Pfeiffer effect is an optical phenomenon whereby the presence of an optically active compound influences the optical rotation of a racemic mixture of a second compound.
Racemic mixtures do not rotate plane polarized light, but the equilibrium concentration of the two enantiomers can shift from unity in the presence of a strongly interacting chiral species. Paul Pfeiffer, a student of Alfred Werner and inventor of the salen ligand, reported this phenomenon. The first example of the effect is credited to Eligio Perucca, who observed optical rotations in the visible part of the spectrum when crystals of sodium chlorate, which are chiral and colourless, were stained with a racemic dye. The effect is attributed to the interaction of the optically pure substance with the second coordination sphere of the racemate.
References
Polarization (waves)
Stereochemistry
Transition metals
Coordination chemistry | Pfeiffer effect | [
"Physics",
"Chemistry"
] | 182 | [
"Stereochemistry",
"Coordination chemistry",
"Astrophysics",
"Space",
"Stereochemistry stubs",
"nan",
"Spacetime",
"Polarization (waves)"
] |
14,476,027 | https://en.wikipedia.org/wiki/DEAD%20box | DEAD box proteins are involved in an assortment of metabolic processes that typically involve RNAs, but in some cases also other nucleic acids. They are highly conserved in nine motifs and can be found in most prokaryotes and eukaryotes, but not all. Many organisms, including humans, contain DEAD-box (SF2) helicases, which are involved in RNA metabolism.
DEAD box family
DEAD box proteins were first brought to attention in the late 1980s in a study that looked at a group of NTP binding sites that were similar in sequence to the eIF4A RNA helicase sequence. The results of this study showed that these proteins (p68, SrmB, MSS116, vasa, PL10, mammalian eIF4A, yeast eIF4A) involved in RNA metabolism had several common elements. There were nine common sequences found to be conserved amongst the studied species, which is an important criterion of the DEAD box family.
The nine conserved motif from the N-terminal to the C-terminal are named as follows: Q-motif, motif 1, motif 1a, motif 1b, motif II, motif III, motif IV, motif V, and motif VI, as shown in the figure. Motif II is also known as the Walker B motif and contains the amino acid sequence D-E-A-D (asp-glu-ala-asp), which gave this family of proteins the name “DEAD box”. Motif 1, motif II, the Q motif, and motif VI are all needed for ATP binding and hydrolysis, while motifs, 1a, 1b, III, IV, and V may be involved in intramolecular rearrangements and RNA interaction.
Related families
The DEAH and SKI2 families have had proteins that have been identified to be related to the DEAD box family. These two relatives have a few particularly unique motifs that are conserved within their own family.
DEAD box, DEAH, and the SKI2 families are collectively referred to as DExD/H proteins. It is thought that each family has a specific role in RNA metabolism, for example both DEAD box and DEAH box proteins NTPase activities become stimulated by RNA, but DEAD box proteins use ATP and DEAH does not.
Biological functions
DEAD box proteins are considered to be RNA helicases and many have been found to be required in cellular processes such as RNA metabolism, including nuclear transcription, pre-mRNA splicing, ribosome biogenesis, nucleocytoplasmic transport, translation, RNA decay and organellar gene expression.
Pre-mRNA splicing
Pre-mRNA splicing requires rearrangements of five large RNP complexes, which are snRNPs U1, U2, U4, U5, and U6. DEAD box proteins are helicases that perform unwinding in an energy-dependent approach and are able to perform these snRNP rearrangements in a quick and efficient manner. There are three DEAD box proteins in the yeast system, Sub2, Prp28, and Prp5, which have been proven to be required for in vivo splicing. Prp5 has been shown to assist in a conformational rearrangement of U2 snRNA, which makes the branch point–recognition sequence of U2 available to bind the branch point sequence. Prp28 may have a role in recognizing the 5’ splice site and does not display RNA helicase activity, suggesting that other factors must be present in order to activate Prp28. DExD/H proteins have also been found to be required components in pre- mRNA splicing, in particular the DEAH proteins, Prp2, Prp16, Prp22, Prp43, and Brr213. As shown in the figure, DEAD box proteins are needed in the initial steps of spliceosome formation, while DEAH box proteins are indirectly required for the transesterifications, release of the mRNA, and recycling of the spliceosome complex9.
Translation initiation
The eIF4A translation initiation factor was the first DEAD box protein found to have an RNA-dependent ATPase activity. It has been proposed that this abundant protein helps in unwinding the secondary structure in the 5'-untranslated region. This can inhibit the scanning process of the small ribosomal subunit, if not unwound. Ded1 is another DEAD box protein that is also needed for translation initiation, but its exact role in this process is still obscure. Vasa, a DEAD box protein highly related to Ded1 plays a part in translation initiation by interacting with eukaryotic initiation factor 2 (eIF2).
See also
DDX3X
DEAD/DEAH box helicase
RNA helicase
Walker A motif
References
Protein domains | DEAD box | [
"Biology"
] | 992 | [
"Protein domains",
"Protein classification"
] |
14,476,384 | https://en.wikipedia.org/wiki/Mass%20versus%20weight | In common usage, the mass of an object is often referred to as its weight, though these are in fact different concepts and quantities. Nevertheless, one object will always weigh more than another with less mass if both are subject to the same gravity (i.e. the same gravitational field strength).
In scientific contexts, mass is the amount of "matter" in an object (though "matter" may be difficult to define), but weight is the force exerted on an object's matter by gravity. At the Earth's surface, an object whose mass is exactly one kilogram weighs approximately 9.81 newtons, the product of its mass and the gravitational field strength there. The object's weight is less on Mars, where gravity is weaker; more on Saturn, where gravity is stronger; and very small in space, far from significant sources of gravity, but it always has the same mass.
Material objects at the surface of the Earth have weight despite such sometimes being difficult to measure. An object floating freely on water, for example, does not appear to have weight since it is buoyed by the water. But its weight can be measured if it is added to water in a container which is entirely supported by and weighed on a scale. Thus, the "weightless object" floating in water actually transfers its weight to the bottom of the container (where the pressure increases). Similarly, a balloon has mass but may appear to have no weight or even negative weight, due to buoyancy in air. However the weight of the balloon and the gas inside it has merely been transferred to a large area of the Earth's surface, making the weight difficult to measure. The weight of a flying airplane is similarly distributed to the ground, but does not disappear. If the airplane is in level flight, the same weight-force is distributed to the surface of the Earth as when the plane was on the runway, but spread over a larger area.
A better scientific definition of mass is its description as being a measure of inertia, which is the tendency of an object to not change its current state of motion (to remain at constant velocity) unless acted on by an external unbalanced force. Gravitational "weight" is the force created when a mass is acted upon by a gravitational field and the object is not allowed to free-fall, but is supported or retarded by a mechanical force, such as the surface of a planet. Such a force constitutes weight. This force can be added to by any other kind of force.
While the weight of an object varies in proportion to the strength of the gravitational field, its mass is constant, as long as no energy or matter is added to the object. For example, although a satellite in orbit (essentially a free-fall) is "weightless", it still retains its mass and inertia. Accordingly, even in orbit, an astronaut trying to accelerate the satellite in any direction is still required to exert force, and needs to exert ten times as much force to accelerate a 10ton satellite at the same rate as one with a mass of only 1 ton.
Overview
Mass is (among other properties) an inertial property; that is, the tendency of an object to remain at constant velocity unless acted upon by an outside force. Under Sir Isaac Newton's -year-old laws of motion and an important formula that sprang from his work, an object with a mass, m, of one kilogram accelerates, a, at one meter per second per second (about one-tenth the acceleration due to Earth's gravity) when acted upon by a force, F, of one newton.
Inertia is seen when a bowling ball is pushed horizontally on a level, smooth surface, and continues in horizontal motion. This is quite distinct from its weight, which is the downwards gravitational force of the bowling ball one must counter when holding it off the floor. The weight of the bowling ball on the Moon would be one-sixth of that on the Earth, although its mass remains unchanged. Consequently, whenever the physics of recoil kinetics (mass, velocity, inertia, inelastic and elastic collisions) dominate and the influence of gravity is a negligible factor, the behavior of objects remains consistent even where gravity is relatively weak. For instance, billiard balls on a billiard table would scatter and recoil with the same speeds and energies after a break shot on the Moon as on Earth; they would, however, drop into the pockets much more slowly.
In the physical sciences, the terms "mass" and "weight" are rigidly defined as separate measures, as they are different physical properties. In everyday use, as all everyday objects have both mass and weight and one is almost exactly proportional to the other, "weight" often serves to describe both properties, its meaning being dependent upon context. For example, in retail commerce, the "net weight" of products actually refers to mass, and is expressed in mass units such as grams or ounces (see also Pound: Use in commerce). Conversely, the load index rating on automobile tires, which specifies the maximum structural load for a tire in kilograms, refers to weight; that is, the force due to gravity. Before the late 20th century, the distinction between the two was not strictly applied in technical writing, so that expressions such as "molecular weight" (for molecular mass) are still seen.
Because mass and weight are separate quantities, they have different units of measure. In the International System of Units (SI), the kilogram is the basic unit of mass, and the newton is the basic unit of force. The non-SI kilogram-force is also a unit of force typically used in the measure of weight. Similarly, the avoirdupois pound, used in both the Imperial system and U.S. customary units, is a unit of mass, and its related unit of force is the pound-force.
Converting units of mass to equivalent forces on Earth
When an object's weight (its gravitational force) is expressed in "kilograms", this actually refers to the kilogram-force (kgf or kg-f), also known as the kilopond (kp), which is a non-SI unit of force. All objects on the Earth's surface are subject to a gravitational acceleration of approximately 9.8 m/s2. The General Conference on Weights and Measures fixed the value of standard gravity at precisely 9.80665 m/s2 so that disciplines such as metrology would have a standard value for converting units of defined mass into defined forces and pressures. Thus the kilogram-force is defined as precisely 9.80665 newtons. In reality, gravitational acceleration (symbol: g) varies slightly with latitude, elevation and subsurface density; these variations are typically only a few tenths of a percent. See also Gravimetry.
Engineers and scientists understand the distinctions between mass, force, and weight. Engineers in disciplines involving weight loading (force on a structure due to gravity), such as structural engineering, convert the mass of objects like concrete and automobiles (expressed in kilograms) to a force in newtons (by multiplying by some factor around 9.8; 2 significant figures is usually sufficient for such calculations) to derive the load of the object. Material properties like elastic modulus are measured and published in terms of the newton and pascal (a unit of pressure related to the newton).
Buoyancy and weight
Usually, the relationship between mass and weight on Earth is highly proportional; objects that are a hundred times more massive than a one-liter bottle of soda almost always weigh a hundred times more—approximately 1,000 newtons, which is the weight one would expect on Earth from an object with a mass slightly greater than 100 kilograms. Yet, this is not always the case and there are familiar objects that violate this proportionality.
A common helium-filled toy balloon is something familiar to many. When such a balloon is fully filled with helium, it has buoyancy—a force that opposes gravity. When a toy balloon becomes partially deflated, it often becomes neutrally buoyant and can float about the house a meter or two off the floor. In such a state, there are moments when the balloon is neither rising nor falling and—in the sense that a scale placed under it has no force applied to it—is, in a sense perfectly weightless (actually as noted below, weight has merely been redistributed along the Earth's surface so it cannot be measured). Though the rubber comprising the balloon has a mass of only a few grams, which might be almost unnoticeable, the rubber still retains all its mass when inflated.
Again, unlike the effect that low-gravity environments have on weight, buoyancy does not make a portion of an object's weight vanish; the missing weight is instead being borne by the ground, which leaves less force (weight) being applied to any scale theoretically placed underneath the object in question (though one may perhaps have some trouble with the practical aspects of accurately weighing something individually in that condition). If one were however to weigh a small wading pool that someone then entered and began floating in, they would find that the full weight of the person was being borne by the pool and, ultimately, the scale underneath the pool. Whereas a buoyant object (on a properly working scale for weighing buoyant objects) would weigh less, the object/fluid system becomes heavier by the value of object's full mass once the object is added. Since air is a fluid, this principle applies to object/air systems as well; large volumes of air—and ultimately the ground—supports the weight a body loses through mid-air buoyancy.
The effects of buoyancy do not just affect balloons; both liquids and gases are fluids in the physical sciences, and when all macrosize objects larger than dust particles are immersed in fluids on Earth, they have some degree of buoyancy. In the case of either a swimmer floating in a pool or a balloon floating in air, buoyancy can fully counter the gravitational weight of the object being weighed, for a weighing device in the pool. However, as noted, an object supported by a fluid is fundamentally no different from an object supported by a sling or cable—the weight has merely been transferred to another location, not made to disappear.
The mass of "weightless" (neutrally buoyant) balloons can be better appreciated with much larger hot air balloons. Although no effort is required to counter their weight when they are hovering over the ground (when they can often be within one hundred newtons of zero weight), the inertia associated with their appreciable mass of several hundred kilograms or more can knock fully grown men off their feet when the balloon's basket is moving horizontally over the ground.
Buoyancy and the resultant reduction in the downward force of objects being weighed underlies Archimedes' principle, which states that the buoyancy force is equal to the weight of the fluid that the object displaces. If this fluid is air, the force may be small.
Buoyancy effects of air on measurement
Normally, the effect of air buoyancy on objects of normal density is too small to be of any consequence in day-to-day activities. For instance, buoyancy's diminishing effect upon one's body weight (a relatively low-density object) is that of gravity (for pure water it is about that of gravity). Furthermore, variations in barometric pressure rarely affect a person's weight more than ±1 part in 30,000. However, in metrology (the science of measurement), the precision mass standards for calibrating laboratory scales and balances are manufactured with such accuracy that air density is accounted for to compensate for buoyancy effects. Given the extremely high cost of platinum-iridium mass standards like the international prototype of the kilogram (the mass standard in France that defined the magnitude of the kilogram), high-quality "working" standards are made of special stainless steel alloys with densities of about 8,000 kg/m3, which occupy greater volume than those made of platinum-iridium, which have a density of about 21,550 kg/m3. For convenience, a standard value of buoyancy relative to stainless steel was developed for metrology work and this results in the term "conventional mass". Conventional mass is defined as follows: "For a mass at 20 °C, ‘conventional mass’ is the mass of a reference standard of density 8,000 kg/m3 which it balances in air with a density of 1.2 kg/m3." The effect is a small one, 150 ppm for stainless steel mass standards, but the appropriate corrections are made during the manufacture of all precision mass standards so they have the true labeled mass.
Whenever a high-precision scale (or balance) in routine laboratory use is calibrated using stainless steel standards, the scale is actually being calibrated to conventional mass; that is, true mass minus 150 ppm of buoyancy. Since objects with precisely the same mass but with different densities displace different volumes and therefore have different buoyancies and weights, any object measured on this scale (compared to a stainless steel mass standard) has its conventional mass measured; that is, its true mass minus an unknown degree of buoyancy. In high-accuracy work, the volume of the article can be measured to mathematically null the effect of buoyancy.
Types of scales and what they measure
When one stands on a balance-beam-type scale at a doctor’s office, they are having their mass measured directly. This is because balances ("dual-pan" mass comparators) compare the gravitational force exerted on the person on the platform with that on the sliding counterweights on the beams; gravity is the force-generating mechanism that allows the needle to diverge from the "balanced" (null) point. These balances could be moved from Earth's equator to the poles and give exactly the same measurement, i.e. they would not spuriously indicate that the doctor's patient became 0.3% heavier; they are immune to the gravity-countering centrifugal force due to Earth's rotation about its axis. But if one steps onto spring-based or digital load cell-based scales (single-pan devices), one is having one's weight (gravitational force) measured; and variations in the strength of the gravitational field affect the reading. In practice, when such scales are used in commerce or hospitals, they are often adjusted on-site and certified on that basis, so that the mass they measure, expressed in pounds or kilograms, is at the desired level of accuracy.
Use in United States commerce
In the United States of America the United States Department of Commerce, the Technology Administration, and the National Institute of Standards and Technology (NIST) have defined the use of mass and weight in the exchange of goods under the Uniform Laws and Regulations in the areas of legal metrology and engine fuel quality in NIST Handbook 130:
K. "Mass" and "Weight" [See Section K. NOTE]
The mass of an object is a measure of the object’s inertial property, or the amount of matter it contains. The weight of an object is a measure of the force exerted on the object by gravity, or the force needed to support it. The pull of gravity on the earth gives an object a downward acceleration of about 9.8 m/s2. In trade and commerce and everyday use, the term "weight" is often used as a synonym for "mass". The "net mass" or "net weight" declared on a label indicates that the package contains a specific amount of commodity exclusive of wrapping materials. The use of the term "mass" is predominant throughout the world, and is becoming increasingly common in the United States.
(Added 1993)
Section K. NOTE: When used in this law (or regulation), the term "weight" means "mass". (see paragraphs K. "Mass" and "Weight" and L. Use of the Terms "Mass" and "Weight" in Section I. Introduction of NIST Handbook 130 for an explanation of these terms.)
(Note Added 1993)
L. Use of the Terms "Mass" and "Weight" [See Section K. NOTE]
When used in this handbook, the term "weight" means "mass". The term "weight" appears when inch-pound units are cited, or when both inch-pound and SI units are included in a requirement. The terms "mass" or "masses" are used when only SI units are cited in a requirement. The following note appears where the term "weight" is first used in a law or regulation.
U.S. federal law, which supersedes this handbook, also defines weight, particularly Net Weight, in terms of the avoirdupois pound or mass pound. From 21 CFR § 101.105 Declaration of net quantity of contents when exempt:
(a) The principal display panel of a food in package form shall bear a declaration of the net quantity of contents. This shall be expressed in the terms of weight, measure, numerical count, or a combination of numerical count and weight or measure. The statement shall be in terms of fluid measure if the food is liquid, or in terms of weight if the food is solid, semisolid, or viscous, or a mixture of solid and liquid; except that such statement may be in terms of dry measure if the food is a fresh fruit, fresh vegetable, or other dry commodity that is customarily sold by dry measure. If there is a firmly established general consumer usage and trade custom of declaring the contents of a liquid by weight, or a solid, semisolid, or viscous product by fluid measure, it may be used. Whenever the Commissioner determines that an existing practice of declaring net quantity of contents by weight, measure, numerical count, or a combination in the case of a specific packaged food does not facilitate value comparisons by consumers and offers opportunity for consumer confusion, he will by regulation designate the appropriate term or terms to be used for such commodity.
(b)(1) Statements of weight shall be in terms of avoirdupois pound and ounce.
See also 21 CFR § 201.51 – Declaration of net quantity of contents for general labeling and prescription labeling requirements.
See also
Apparent weight
Gravimeter
Pound (force)
References
Concepts in physics
Mass
Force
Conceptual distinctions | Mass versus weight | [
"Physics",
"Mathematics"
] | 3,818 | [
"Scalar physical quantities",
"Force",
"Physical quantities",
"Quantity",
"Mass",
"Classical mechanics",
"Size",
"nan",
"Wikipedia categories named after physical quantities",
"Matter"
] |
14,476,666 | https://en.wikipedia.org/wiki/Lunar%20Design | Founded in 1984 by Jeff Smith, Gerard Furbershaw and Robert Brunner, LUNAR (Lunar Design) is a product design and development consultancy headquartered in the San Francisco Bay Area. The company's provides industrial, interaction and communication design; video story telling, mechanical and electrical engineering, manufacturing support, user validation, design research, and need finding & assessment. Its current and past clients include Apple Inc., Abbott Labs, Cisco Systems, Hewlett-Packard, Johnson & Johnson, Microsoft, Motorola, Philips, Oral-B, Palm, Pepsi and Sony. On May 14, 2015, Lunar was acquired by management consulting firm McKinsey & Company.
Lunar Design partnered with Nova Cruz to design and develop the Xootr Scooter.
Affiliates
LUNAR has offices in California, Chicago, and Europe (Munich, Germany). LUNAR Europe GmbH http://lunar-europe.com was founded in January, 2007 and is headed by Roman Gebhard and Matthis Hamann. The Chicago office was started in 2011 and is led by Mark Dziersk.
Achievement and awards
LUNAR was one of the top five award-winning industrial design firms for over 10 years, according to BusinessWeek magazine. The firm has been recognized with accolades from the Industrial Designers Society of America IDEA Awards, Fast Company "Innovation by Design" Awards, Core 77 Design Awards, CES Innovations Design and Engineering Awards, iF Hannover Product Design Awards, and the ID Magazine Design Annual award, among others.
Two of LUNAR product designs for Oral-B and Philips were featured in the “Prototype to Product” exhibit in the United Airlines terminal at the San Francisco International Airport in 2007.
References
External links
Official Website
Design companies established in 1984
1984 establishments in California
2015 mergers and acquisitions
Industrial design firms
Companies based in San Francisco
Design companies of the United States | Lunar Design | [
"Engineering"
] | 369 | [
"Design stubs",
"Design"
] |
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