Persius/hicric huggingface dataset:
Delocalized electron

# Overview
In chemistry delocalized electrons are electrons in a molecule that are not associated with a single atom or to a covalent bond. Delocalized electrons are contained within an orbital that extends over several adjacent atoms.  Classically, delocalized electrons can be found in conjugated systems of double bonds and in aromatic and mesoionic systems. A case of delocalized electrons occurs also in solid metals, where the d-subshell interferes with the above s-subshell, and contributes to the properties of a metal.  It is increasingly appreciated that electrons in sigma bonding levels are also delocalized.  For example, in methane, the bonding electrons are shared by all five atoms equally.  Pervasive existence of delocalization is implicit in Molecular Orbital Theory.
In the simple aromatic ring of benzene the delocalization of six  electrons over the C6 ring is often graphically indicated by a circle.  The fact that the six C-C bonds are equidistant is one indication of this delocalization.  In Valence Bond Theory, delocalization in benzene is represented by resonance structures.
Another example of a delocalized electrons can be found in a carboxylate group, wherein the negative charge is centered equally on the two oxygen atoms.
Delocalized electrons are important for several reasons. One, an expected chemical reaction may not occur because the electrons delocalize to a more stable configuration, resulting in a reaction that happens at a different location. An example attempting the Fridel-Crafts alkylation of benzene with 1-chloro-2-methylpropane; the carbocation rearranges to a tert-butyl group stabilized by hyperconjugation, a particular form of delocalization.
Delocalized electrons also exist in the structure of metals. Metallic structure consist of aligned positive ions (cations) in a "sea" of delocalized electrons. This means that the electrons are free to move throughout the structure, and gives rise to properties such as conductivity.
In diamond all four outer electrons of each carbon atom are 'localized' between the atoms in covalent bonding. The movement of electrons is restricted and diamond does not conduct an electric current. In graphite, each carbon atom uses only 3 of its 4 outer energy level electrons in covalently bonding to three other carbon atoms in a plane. Each carbon atom contributes one electron to a delocalized system of electrons that is also a part of the chemical bonding. The delocalized electrons are free to move throughout the plane. For this reason, graphite conducts electricity along the planes of carbon atoms, but does not conduct in a direction at right angles to the plane.
Dental public health

# Overview
Dental public health  is a non-clinical speciality of Dentistry
Dental public health is involved in the  assessment of dental health needs and  improving the dental health of populations rather than individuals
There are a few training opportunities to obtain an MSc in Dental public health.
One of the controversial subjects relating to dental public health is Fluoridation of drinking water.
Deoxyribonuclease II
Deoxyribonuclease II (EC 3.1.22.1, DNase II, pancreatic DNase II, deoxyribonucleate 3'-nucleotidohydrolase, pancreatic DNase II, acid deoxyribonuclease, acid DNase) is an endonuclease that hydrolyzes phosphodiester linkages of deoxyribonucleotide in native and denatured DNA, yielding products with 3'-phosphates and 5'-hydroxyl ends, which occurs as a result of single-strand cleaving mechanism. As the name implies, it functions optimally at acid pH because it is commonly found in low pH environment of lysosomes.
The action of DNase occurs in three phases. The initial phase introduces multiple nicks in the phosphodiester backbone. The second phase produces acid-soluble nucleotides. The third phase, which is the terminal phase, consists of hyperchromic shift resulting from reduction of oligonucleotides. 
There are several known DNases II, including:
- DNase II alpha (usually known as DNase II), which is thought to be ubiquitously expressed in human tissue. It has been shown that a mutation in this enzyme of mice leads to DNA degradation by apoptosis.
- DNase II beta (also called DLAD, or DNase II-Like Acid DNase), which is mainly expressed in the eye lens and salivary glands. One of its functions is to clear DNA from eye lens. Low levels have also been detected in the lung, prostate and lymph nodes. Deficiency of this enzyme in mice lead to the development of cataracts.
Deposition (physics)
Deposition is a process in which gas transforms into solid (also known as desublimation). The reverse of deposition is sublimation.
One example of deposition is the process by which, in sub-freezing air, water vapor changes directly to ice without first becoming a liquid.  This is how snow forms in clouds, as well as frost and hoar frost on the ground.
Another example of physical deposition is the artificial process of physical vapor deposition, used to deposit thin films of various materials onto various surfaces.
Deposition releases energy and is an exothermic phase change.
Derby plague of 1665
During the Great Plague of 1665 the area of Derby, England fell victim to the bubonic plague, with many deaths.  Some areas of Derby still carry names that record the 1665 visitation,  Blagreaves Lane was Black Graves while Dead Man's Lane speaks for itself. It has been claimed by some historians that bodies were buried standing upright at St. Peter's Church, Derby, but this legend has been refuted by experts.
Trade was carried out at a Market Stone on Ashbourne Road which leads into the Town Centre.  During the epidemic, trade almost ceased and the population faced possible starvation, as well as a cruel death by infection with the plague.
Market stones took many forms, here we see the stone placed at Friar Gate (formerly Nuns Green) at the northern road into Derby (England). This was a medieval headless cross, and also called the "Vinegar Stone" because money was deposited in a trough of vinegar in the top of the stone in the belief that the vinegar would disinfect the coins and prevent the spread of the plague.
Desoxycorticosterone

# Overview
Desoxycorticosterone (11-deoxycorticosterone) is a mineralocorticoid secreted from Zona reticularis and Zona fasciculata of the adrenal gland.  In the cytosol of the mitochondrion, pregnenolone is converted to either androgens or 11-deoxycorticosterone and 11-deoxycortisol by enzymes of the endoplasmic reticulum.  Then, 11-deoxycorticosterone, along with 11-deoxycortisol, re-enters the mitochondrion, where the enzymes are located for tissue-specific conversion to mineralocorticoids or glucocorticoids, respectively.
Desoxycorticosterone is commonly found in two forms: the acetate salt (desoxycorticosterone acetate, or DOCA) and the pivalate salt (desoxycorticosterone pivalate).  Both forms are given as intramuscular injections as replacement therapy for Addison's disease.  This disease is marked by insufficient adrenal function, including low mineralocorticoid levels.
Desoxycorticosterone pivalate is sold for veterinary use by Novartis under the brand name Percoten.
Diabetic myonecrosis
Diabetic myonecrosis is a rare complication of diabetes.  It is caused by infarcted muscle tissue, usually in the thigh.

# Epidemiology
The mean age at presentation is thirty-seven years with a reported range of nineteen to sixty-four years. The mean age of onset  since diagnosis of diabetes is fifteen years. The female:male ratio is 1.3:1. Other diabetic complications such as nephropathy, neuropathy, retinopathy and hypertension are usually present. Its major symptom is the acute onset muscle pain, usually in the thigh, in the absence of trauma. Signs include exquisite muscle tenderness and swelling.

# Investigations and diagnosis
Tissue biopsy is the gold standard.  Macroscopically this reveals pale muscle tissue.  Microscopically infarcted patches of myocytes.  Necrotic muscle fibers are swollen and eosinophilic and lack striations and nuclei.  Small-vessel walls are thickened and hyalinized, with luminal narrowing or complete occlusion.  Biopsy cultures for bacteria, fungi, acid-fast bacilli and stains are negative in simple myonecrosis.
Creatine kinase is found to be normal.  ESR is elevated. Planar X-ray reveals soft tissue swelling and bone scan shows non specific uptake.  CT shows muscle oedema with preserved tissue planes (non-contrast enhancing). MRI shows increased signal on T2 weighted images within areas of muscle oedema.  Arteriography reveals large and medium vessel arteriosclerosis occasionally with dye within the area of tissue infarction .  Electromyography shows non specific focal changes.

# Treatment
Treatment includes supportive care with analgesics and anti-inflammatory agents. Exercise should be limited as it increases pain and extends the area of infarction. Symptoms usually resolve in weeks to months, but fifty percent of sufferers will experience relapse in either leg. The majority diagnosed with diabetic myonecrosis die within 5 years.

# Pathophysiology
The pathogenesis of this disease is unclear. Arteriosclerosis obliterans has been postulated as the cause, along with errors of the clotting and fibrinolytic pathways such as antiphospholipid syndrome.

# Differential Diagnosis
A large number of conditions may cause symptoms and signs similar to diabetic myonecrosis and include:  deep vein thrombosis, thrombophlebitis, cellulitis, fasciitis, abscess, haematoma, myositis, pseudothrombophlebitis (ruptured synovial cyst), pyomyositis, parasitic myositis, osteomyelitis, calcific myonecrosis, myositis ossificans, diabetic myotrophy, muscle strain or rupture, bursitis, vasculitis, arterial occlusion, haemangioma, lymphoedema, sarcoidosis, tuberculosis, cat-scratch disease, amyloidosis, as well as tumours of lipoma, chondroma, fibroma, leiomyoma and sarcoma.
Dibenzylideneacetone
Dibenzylideneacetone or dibenzalacetone, often abbreviated dba, is an organic compound with the formula C17H14O. It is a bright yellow solid insoluble in water, but soluble in ethanol. Dibenzylideneacetone is used as a sunscreen component and it is used as a ligand in organometallic chemistry for instance in tris(dibenzylideneacetone)dipalladium(0). In this case, it is a labile ligand which is easily displaced by stronger ligands like triphenylphosphine, hence it serves a useful entry point into palladium(0) chemistry.

# Preparation
The compound can be prepared in the laboratory by an aldol condensation of benzaldehyde and acetone with sodium hydroxide in a water / ethanol medium with the exclusive formation of the trans,trans isomer (melting point 107111 C).
This reaction is frequently encountered in organic chemistry education as a laboratory procedure. The conversion proceeds via the intermediacy of benzylideneacetone.
Prolonged exposure to sunlight converts the compound in a  cycloaddition to a mixture of four cyclobutane isomers.
Diego antigen system

# The Diego blood group

# History
The Diego system was discovered in 1955 in one Mrs. Diego when her child was found to suffer from HDN. The child was type Dia. A second type Dib was discovered in 1967 but the other types only began to be discovered in 1995.  , 

# Definition
Blood is classified in the Diego system by the form of the band 3 protein, coded for by the gene SLC41A (Solute Carrier family 4, Anion exchanger, member 1). Each allele of the gene SLC41A is classified as a separate blood group.
The band 3 protein functions in the transport of Cl- and carbonate.

# The system
There are 21 known Diego blood types, the most common is Di(a-b+); found in over 99.9% of Caucasians and Blacks, and in about 90% of Asians. Most of the remaining 10% of Asians are (a+b+). The cultural distribution of the blood group lends it some importance to the science of anthropology.
Dientamoeba fragilis

# Overview
Dientamoeba fragilis is a single celled parasite that infects the gastrointestinal tract of humans.  Trophozoites of D. fragilis characteristically have two nuclei, hence the 'DI' prefix to the genus name. However, the rest of the genus name indicates that it is an ENTeric AMOEBA and not that it is related to intestinal parasites of the genus Entamoeba. The species name refers to the fact that the trophozoite stages are fragile - they do not survive long in the stool after leaving the body of the human host.

# Dientamoebiasis
Infection with Dientamoeba fragilis is called Dientamoebiasis and is associated variously with symptoms of abdominal pain, diarrhea, weight loss, and fever.

# Phylogenetics
Dientamoeba fragilis is a type of trichomonad. Trichomonads are flagellated organisms but D. fragilis lacks flagella, having secondarily 'lost' them over evolutionary time. Thus, it is an amoeba of flagellate ancestry.

# Life Cycle
The life cycle of this parasite has not yet been completely determined, but some assumptions have been made based on clinical data. To date, a cyst stage has not been identified in D. fragilis, and the trophozoite is the only stage found in stools of infected individuals. Like other intestinal parasites, D. fragilis is probably transmitted by the fecal-oral route. In the absence of a cyst form, transmission via helminth eggs (e.g., Ascaris, Enterobius spp.) has been postulated. The rationale for this suggestion is that D. fragilis is closely related to the turkey parasite Histomonas, which is known to be transmitted via the eggs of the helminth Heterakis.

# Microbiology
Dientamoeba fragilis replicates by binary fission and moves by pseudopodia. D. fragilis feeds by phagocytosis. The cytoplasm typically contains numerous food vacuoles that contain ingested debris, including bacteria. Waste materials are eliminated from the cell through digestive vacuoles by exocytosis. D. fragilis possesses some flagellate characteristics. In the binucleate form there is a spindle structure located between the nuclei, which stems from certain polar configurations adjacent to a nucleusthese configurations appear to be homologous to hypermastigotes atractophores. There is a complex Golgi apparatus; the nuclear structure of D. fragilis is more similar to that of flagellated trichomonads than to that of Entamoeba.  Also notable is the presence of hydrogenosomes, which are also a characteristic of other trichomonads.

# Gallery
- Iron-hematoxylin stained photomicrograph depicts a binucleated amoebic trophozoite of a Dientamoeba fragilis parasite. From Public Health Image Library (PHIL). 
- Photomicrograph reveals the presence of a trichrome-stained, Dientamoeba fragilis parasitic trophozoites in this specimen. From Public Health Image Library (PHIL). 
- Photomicrograph reveals the presence of a trichrome-stained, Dientamoeba fragilis parasitic trophozoites in this specimen. From Public Health Image Library (PHIL). 
- Trichrome-stained photomicrograph reveals the presence of a parasitic Dientamoeba fragilis trophozoite (1150x mag). From Public Health Image Library (PHIL).
Dilator naris muscle
The Dilator naris muscle is a part of the nasalis muscle. It is divided into posterior and anterior parts.
- The Dilator naris posterior is placed partly beneath the Quadratus labii superioris. It arises from the margin of the nasal notch of the maxilla, and from the lesser alar cartilages, and is inserted into the skin near the margin of the nostril.
- The Dilator naris anterior is a delicate fasciculus, passing from the greater alar cartilage to the integument near the margin of the nostril; it is situated in front of the Dilatator naris posterior muscle.
Dimethyl dicarbonate
Dimethyl dicarbonate or DMDC is a colourless liquid with a sharp odour. Its primary use is as a beverage preservative or sterilant (INS No. 242), and acts by inhibiting the enzymes acetate kinase and L-glutamic acid decarboxylase . It has also been proposed that methoxycarbonylation of the histidine part of the enzymes alcohol dehydrogenase and glyceraldehyde 3-phosphate dehydrogenase by DMDC inhibits these essential enzymes also . Once it has been added to beverages, the efficacy of the chemical is provided by the following reactions:
- DMDC + H2O  2CH3OH + 2CO2
- DMDC + ROH  Ethyl methyl carbonate
- DMDC + NH3  Methyl carbamate
- DMDC + Amino acid  Derived carboxymethyl
DMDC is sometimes used as a preservative in wine as a replacement to sulfur dioxide, inactivating wine spoilage yeasts such as Brettanomyces. In the U.S. the FDA approved its use in wines in 1998, with the maximum permitted level being set at 200mg/L, and only if there was less than 500 yeast cells/mL at time of dosage. Usage has also been approved in Germany (since 1978) and New Zealand. The application of DMDC is particularly useful when wine needs to be sterilised but cannot be sterile filtered, pasteurized, or sulfured.
DMDC has also been used to sterilise coffee, tea, cider, fruit wine and mead.
Disease transmission
Disease transmission is the way that an infectious disease or pathogen is "passed on" or "communicated" from one individual to another in a population of humans, or in groups of other animals. Disease can be transmitted in two ways:
- Horizontal disease transmission  from one individual to another in the same generation (piers in the same age group). Horizontal transmission can occur by either direct contact (licking, touching, biting), or indirect contact (vectors or fomites that allow the transmission of disease without physical contact).
- Vertical disease transmission  passing a disease causing agent vertically from parent to offspring. Typically the mother transmits the disease by means of bodily fluid, and sometimes breast milk.
Disseminated disease

# Overview
Disseminated disease refers to a diffuse disease process, generally either infectious or neoplastic, but sometimes also referring to connective tissue disease.
A disseminated infection, for example, is one that has extended beyond its origin or nidus and involved the bloodstream to "seed" other areas of the body. Similarly, metastatic cancer can be viewed as a disseminated infection in that it has extended into the bloodstream or the lymphatic system to "seed" distant sites (known as metastasis).
Disseminated disease is often referred to in contrast to localized disease.
Domain (mathematics)
In mathematics, the domain of a given function
is the set of "input" values for which the function is defined. In a representation of a function in a xy Cartesian coordinate system, the domain is represented on the abscissa (the x axis).

# Domain of a function
Given a  function f:XY, the set X of input values is the domain of f; the set Y is the codomain of f.
The range of f is the set of all output values of f; this is the set \{ f(x) : x \in X \}.   The range of f can be the same set as the codomain or it can be a proper subset of it.  It is in general smaller than the codomain unless f is a surjective function.
A well defined function must map every element of its domain to an element of its codomain. For example, the function f defined by
has no value for f(0).
Thus, the set of real numbers, \mathbb{R}, cannot be its domain.
In cases like this, the function is either defined on \mathbb{R} \backslash \{0 \} or the "gap is plugged" by explicitly defining f(0).
If we extend the definition of f to
then f is defined for all real numbers, and its domain is \mathbb{R}.
Any function can be restricted to a subset of its domain.
The restriction of g : A  B to S, where S  A, is written g |S : S  B.

# Domain of a partial function
There are two distinct meanings in current mathematical usage for the notion of the domain of a partial function. Most mathematicians, including recursion theorists, use the term "domain of f" for the set of all values x such that f(x) is defined. But some, particularly category theorists, consider the domain of a partial function f:XY to be X, irrespective of whether f(x) exists for every x in X.

# Category theory
In category theory one deals with morphisms instead of functions.  Morphisms are arrows from one object to another.  The domain of any morphism is the object from which an arrow starts.  In this context, many set theoretic ideas about domains must be abandoned or at least formulated more abstractly.  For example, the notion of restricting a morphism to a subset of its domain must be modified.  See subobject for more.

# Real and complex analysis
In real and complex analysis, a domain is an open connected subset of a real or complex vector space.
Dorsal root ganglion

# Overview
In anatomy and neurology, the dorsal root ganglion (or spinal ganglion) is a nodule on a dorsal root that contains cell bodies of neurons in afferent spinal nerves.

# Unique unipolar structure
The axons of dorsal root ganglion neurons are known as afferents. In the peripheral nervous system, affarents refer to the axons that relay sensory information into the central nervous system and spinal cord. These neurons are of the pseudo-unipolar type, meaning they have an axon with two branches that act as a single axon, often referred to as a distal process and a proximal process.
Unlike the majority of neurons found in the central nervous system, an action potential in dorsal root ganglion neuron may initiate in the distal process in the periphery, bypass the cell body, and continue to propagate along the proximal process until reaching the synaptic terminal in the dorsal horn of the spinal cord.

# Distal section
The distal section of the axon may either be a bare nerve ending or encapsulated by a structure that helps relay specific information to nerve. For example, a Meissner's corpuscle or Pacinian corpuscle may encapsulate the rendering the distal process sensitive to mechanical stimulation, such as stroking or vibration, respectively. 

# Location
The dorsal root ganglia lie along the vertebral columna by the spine.

# Embryology
The dorsal root ganglia develops in the embryo from neural crest cells.

# Nociception
G protein-coupled receptor on the DRG have been associated with nociception.