Mada M I M adaM
Theta (UK: /ˈθiːtə/, US: /ˈθeɪtə/) uppercase Θ or ϴ; lowercase θ[note 1] or ϑ; Ancient Greek: θῆτα thē̂ta [tʰɛ̂ːta]; Modern: θήτα thī́ta [ˈθita]) is the eighth letter of the Greek alphabet, derived from the Phoenician letter Teth 
. In the system of Greek numerals, it has a value of 9.
Greek
[edit]
In Ancient Greek, θ represented the aspirated voiceless dental plosive IPA: [t̪ʰ], but in Modern Greek it represents the voiceless dental fricative IPA: [θ].
Forms
[edit]In its archaic form, θ was written as a cross within a circle (as in the Etruscan 
or 
), and later, as a line or point in circle (
or 
).
Lower case
[edit]The lowercase letter θ is used as a symbol for:
- A plane angle in geometry
- An unknown variable in trigonometry
- The voiceless dental fricative, spelled θ
- A special function of several complex variables
- One of the Chebyshev functions in prime number theory
- The potential temperature in meteorology
- The score of a test taker in item response theory
- Theta Type Replication: a type of bacterial DNA replication specific to circular chromosomes
- Threshold value of an artificial neuron
- A Bayer designation letter applied to a star in a constellation; usually the eighth star so labelled but not necessarily the eighth-brightest as viewed from Earth
- The statistical parameter frequently used in writing the likelihood function
- The Watterson estimator for the population mutation rate in population genetics
- Indicates a minimum optimum integration level determined by the intersection of GG and LL schedules (The GG-LL schedules are tools used in analyzing the potential benefits of a country pegging their domestic currency to a foreign currency.)
- The reserve ratio of banks in economic models
- The ordinal collapsing function developed by Solomon Feferman[2]
- Heaviside step function
- In pharmacology, the fraction of ligand bound to a macromolecule based on the Hill Equation
Upper case
[edit]The uppercase letter Θ is used as a symbol for:
- Dimension of temperature, by SI standard (in italics)
- Dimensionless temperature in transport phenomena
- An asymptotically tight bound in the analysis of algorithms (big O notation)
- A certain ordinal number in set theory
- Pentaquarks, exotic baryons in particle physics
- A brain signal frequency (beta, alpha, theta, delta) ranging from 4–8 Hz
- One of the variables known as "Greeks" in finance, representing time decay of options or the change in the intrinsic value of an option divided by the number of days until the option expires
- A variable indicating temperature difference in heat transfer
- Measuring the angle of incident X-ray beam during XRD
The sinoatrial node (also known as the sinuatrial node, SA node or sinus node) is an oval shaped region of special cardiac muscle in the upper back wall of the right atrium made up of cells known as pacemaker cells. The sinus node is approximately 15 mm long, 3 mm wide, and 1 mm thick, located directly below and to the side of the superior vena cava.[1]
These cells can produce an electrical impulse known as a cardiac action potential that travels through the electrical conduction system of the heart, causing it to contract. In a healthy heart, the SA node continuously produces action potentials, setting the rhythm of the heart (sinus rhythm), and so is known as the heart's natural pacemaker. The rate of action potentials produced (and therefore the heart rate) is influenced by the nerves that supply it.[2]
Structure
[edit]The sinoatrial node is an oval-shaped structure that is approximately 15 mm long, 3 mm wide, and 1 mm thick, located directly below and to the side of the superior vena cava.[1] The size can vary but is usually between 10-30 mm long, 5–7 mm wide, and 1–2 mm deep.[3][4]
Location
[edit]The SA node is located in the wall (epicardium) of the right atrium, laterally to the entrance of the superior vena cava in a region called the sinus venarum (hence sino- + atrial).[5] It is positioned roughly between a groove called the crista terminalis located on the internal surface of the heart and the corresponding sulcus terminalis, on the external surface.[2] These grooves run between the entrance of the superior vena cava and the inferior vena cava.
 Sinoatrial node shown at 1. The rest of the conduction system of the heart is shown in blue. | |
| Details | |
|---|---|
| System | Electrical conduction system of the heart |
| Artery | Sinoatrial nodal artery |
| Identifiers | |
| Latin | nodus sinuatrialis |
| Acronym(s) | SA node |
| MeSH | D012849 |
| TA98 | A12.1.06.003 |
| TA2 | 3953 |
| FMA | 9477 |
| Anatomical terminology | |
The hippocampus (pl.: hippocampi; via Latin from Greek ἱππόκαμπος, 'seahorse') is a major component of the brain of humans and other vertebrates. Humans and other mammals have two hippocampi, one in each side of the brain. The hippocampus is part of the limbic system, and plays important roles in the consolidation of information from short-term memory to long-term memory, and in spatial memory that enables navigation. The hippocampus is located in the allocortex, with neural projections into the neocortex, in humans[1][2][3] as well as other primates.[4] The hippocampus, as the medial pallium, is a structure found in all vertebrates.[5] In humans, it contains two main interlocking parts: the hippocampus proper (also called Ammon's horn), and the dentate gyrus.[6][7]
In Alzheimer's disease (and other forms of dementia), the hippocampus is one of the first regions of the brain to suffer damage;[8] short-term memory loss and disorientation are included among the early symptoms. Damage to the hippocampus can also result from oxygen starvation (hypoxia), encephalitis, or medial temporal lobe epilepsy. People with extensive, bilateral hippocampal damage may experience anterograde amnesia: the inability to form and retain new memories.
Since different neuronal cell types are neatly organized into layers in the hippocampus, it has frequently been used as a model system for studying neurophysiology. The form of neural plasticity known as long-term potentiation (LTP) was initially discovered to occur in the hippocampus and has often been studied in this structure. LTP is widely believed to be one of the main neural mechanisms by which memories are stored in the brain.
In rodents as model organisms, the hippocampus has been studied extensively as part of a brain system responsible for spatial memory and navigation. Many neurons in the rat and mouse hippocampus respond as place cells: that is, they fire bursts of action potentials when the animal passes through a specific part of its environment.
| Number | Nome Standard (Symbol on top of head of man or woman) | Ancient Egyptian Nome Name | Ancient Greek and Coptic Nome Name | Capital | Modern name of capital site | God | |||
|---|---|---|---|---|---|---|---|---|---|
| Image | Unicode | Transliteration | Translation | Greek | Coptic | ||||
| 1 |  | 𓈠 | jnb-ḥḏ | White Walls | Μεμφίτης Memphites | ⲙⲛⲫⲉ/ ⲉⲕⲉⲡϯⲁ | jnb-ḥḏ Ineb-Ḥedj ( 𓏠𓈖𓄤𓆑𓂋𓉴𓊖 mn-nfr Mennefer) (Memphis) | Mit Rahina | Ptah |
| 2 |  | 𓈡 | ḫpš Khepesh | Cow's thigh | Λητοπολίτης Letopolites | ⲃⲟⲩϣⲏⲙ | 𓐍𓋉𓅓𓊖 ḫm Khem [Sekhem/ Iry] (Letopolis) | Ausim | Horus |
| 3 |  | 𓈢 | jmntt Imentet/Amentet | West | Γυναικοπολίτης Gynaikopolites | I-am/ Imu (Apis) | Kom El Hisn | Hathor | |
| 4 | 𓈣 | nt-rsj/nt-rsw Nit Resy/Nit Resu | Southern Neith | Προσωπίτης Prosopites | ⲡϣⲁϯ | Niciu | Zawyet el-Razin | ||
| 4 (21) |  | 𓈣 | nt-rsj/rsw Nit Resy/Resu | Southern Neith | Φθεμφουθ Phthemphouth | Ptkheka | Tanta | Sobek, Isis, Amun | |
| 5 |   | 𓈤/𓈥 | nt-mḥtt Nit Meḥtet | Northern Neith | Σαίτης Saites | ⲥⲁⲓ | 𓊃𓅭𓄿𓅱𓊖 zꜣw Sau/ Zau (Sais) | Sa El Hagar | Neith |
| 6 |  | 𓈦 | ḫꜣsww | Mountain bull | Ξοίτης Xoites | ⲥϧⲱⲟⲩ | 𓆼𓋴𓅱𓅱𓏏𓊖 ḫꜣsww Khasu (Xois) | Sakha | Amun-Ra |
| 7 |  | 𓈧 | ḥww-(gs)-jmnty Huu-(ges)-Imenti | West harpoon | Μενελαίτης Menelaites | 𓂧𓏇𓇌𓊖𓏌𓅃𓏤 (Hermopolis Parva, Metelis) | Damanhur | Hu | |
| 8 |  | 𓈨 | ḥww-(gs)-jꜣbty Huu-(ges)-Iabty | East harpoon | Ἡροοπολίτης Heroopolites | Thek/ Tjeku / Iset-Tem 𓉐𓏤𓏏𓍃𓅓𓏏𓊖 pr-jtmw Per-Atum/ Ān (Heroonpolis, Pithom) | Tell al-Maskhuta | Atum | |
| 9 |  | 𓈩 | ꜥnḏty Andjety | Andjety | Βουσιρίτης Bousirites | ⲡⲁⲛⲁⲩ | 𓉐𓏤𓊨𓁹𓎟𓊽𓂧𓅱𓊖 ḏdw Djedu (Busiris) | Abu Sir Bara | Osiris |
| 10 |  | 𓈪 | km-wr/kꜣ-km Kem-Wer/Ka-kem | Black bull | Ἀθριβίτης Athribites | ⲁⲑⲣⲏⲃⲓ | 𓉗𓏏𓉐𓇾𓁷𓄣𓊖 Hut-hery-ib (Athribis) | Banha (Tell Atrib) | Horus |
| 11 |  | 𓈫 | (kꜣ)-ḥsb (Ka)-Heseb | Heseb bull | Λεοντοπολίτης Leontopolites | ⲛⲁⲑⲱ | Taremu/ Ikhenu (Leontopolis) | Tell el-Muqdam | Isis |
| 12 |  | 𓈬 | ṯb-kꜣ/ṯb-nṯr Tjeb-Ka/Tjeb-Netjer | Calf and Cow | Σεβεννύτης Sebennytes | ϫⲉⲙⲛⲟⲩϯ | 𓊹𓍿𓃀𓊖 ṯb-nṯr (Tjeb netjer) (Sebennytos) | Samanud | Anhur |
| 13 |  | 𓈭 | ḥqꜣ-ꜥḏ | Prospering Sceptre | Ἡλιοπολίτης Heliopolites | ⲱⲛ | jwnw (Iunu)/ In-meḥ/ Iset-Tem/ Igert, Igertet, Iqert, Iugertet (Heliopolis) | Materiya (suburb of Cairo) | Ra |
| 14 |  | 𓈮 | ḫnty-jꜣbty Khenti-Iabti | Foremost of the East | Σεθρωίτης Sethroites | Tjaru/ Dj‘anet (Sile, Tanis) | Tell Abu Sefa | Horus | |
| 15 |  | 𓈯 | ḏḥwty Djeḥuti | Thoth | Μενδήσιος Mendesios | ⲛⲓⲙⲉϣϣⲱⲧ | Ba'h / Weprehwy (Hermopolis Parva) | Baqliya | Thoth |
| 16 |  | 𓈰 | ḥꜣt-mḥyt | Fish/ Foremost of the Fish | Μενδήσιος Mendesios | ⲛⲓⲙⲉϣϣⲱⲧ | Djedet/ Ā'atjaba (Mendes) | Tell El Rubˁ | Banebdjedet and Hatmehyt |
| 17 |   | 𓈱/𓈲 | bḥdt/smꜣ-bḥdt Behdet/Sema-Behdet | Throne/ Uniting the throne? | Διοπολίτης Κάτω Diospolites Kato | ⲡⲟⲩⲛⲉⲙⲟⲩ | Sema-behdet (Diospolis Inferior) | Tel El Balamun | Amun-Ra |
| 18 |  | 𓈳 | jmty-ḫnty Imty Khenti | Southern Prince | Βουβαστίτης Boubastites | ⲡⲟⲩⲃⲁⲥϯ | Per-Bastet (Bubastis) | Tell Bastah (near Zagazig) | Bastet |
| 19 |  | 𓈴 | jmty-pḥw Imty Pehu | Northern Prince | Τανίτης Tanites | ϫⲁⲛⲏ | Dja'net (Leontopolis Tanis) | Tell Nebesha or San El Hagar | Wadjet |
| 20 |  | 𓈵 | spdw Sopdu | Sopdu | Ἀραβία Arabia | ϯⲁⲣⲁⲃⲓⲁ | Per-Sopdu | Saft El Hinna | Sopdet |
List
[edit]- Unnamed speakers
| Name | Mentioned |
|---|---|
| Callias' slave | Protagoras |
| Euclides' slave | Theaetetus |
| Meno's slave of Pharsalus | Meno |
| Polemarchus' slave | Republic |
| Public slave | Phaedo |
| Stranger from Athens | Epinomis, Laws |
| Stranger from Elea | Sophist, Statesman |
| Unnamed friends | Eryxias, Hipparchus, Minos, On Justice,[1] On Virtue,[4] Protagoras, Rival Lovers, Symposium |
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