搜尋結果
e. The Oxford–AstraZeneca COVID‑19 vaccine, sold under the brand names Covishield [31] and Vaxzevria [1] [32] among others, is a viral vector vaccine for the prevention of COVID-19. It was developed in the United Kingdom by Oxford University and British-Swedish company AstraZeneca, [33] [34] [35] using as a vector the modified chimpanzee ...
The Oxford–AstraZeneca COVID-19 vaccine, sold under the brand names Vaxzevria [6] and Covishield, [7] is a viral vector vaccine [8] produced by the British University of Oxford, British-Swedish company AstraZeneca, and the Coalition for Epidemic Preparedness Innovations. [8] [9] [10] Finland, Denmark, and Norway suspended the use of the ...
The COVID-19 pandemic, also known as the coronavirus pandemic, is a global pandemic of coronavirus disease 2019 (COVID-19) caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). The novel virus was first identified in an outbreak in Wuhan, the capital of Hubei, China, in December 2019, before it spread to other areas of Asia, and then worldwide in early 2020.
- 新冠肺炎-疫苗資訊最前線
Human papillomavirus infection ( HPV infection) is caused by a DNA virus from the Papillomaviridae family. [5] Many HPV infections cause no symptoms and 90% resolve spontaneously within two years. [1] In some cases, an HPV infection persists and results in either warts or precancerous lesions. [2] These lesions, depending on the site affected ...
- Partial Order Relations
- Notation
- Alternative Definitions
- Examples
- Derived Notions
- Mappings Between Partially Ordered Sets
- Number of Partial Orders
- Subposets
- Linear Extension
- In Category Theory
The term partial order usually refers to the reflexive partial order relations, referred to in this article as non-strict partial orders. However some authors use the term for the other common type of partial order relations, the irreflexive partial order relations, also called strict partial orders. Strict and non-strict partial orders can be put ...
Given a set P {\displaystyle P} and a partial order relation, typically the non-strict partial order ≤ {\displaystyle \leq } , we may uniquely extend our notation to define four partial order relations ≤ , {\displaystyle \leq ,} < , {\displaystyle <,} ≥ , {\displaystyle \geq ,} and > {\displaystyle >} , where ≤ {\displaystyle \leq } is a non-strict...
Another way of defining a partial order, found in computer science, is via a notion of comparison. Specifically, given ≤ , < , ≥ , and > {\displaystyle \leq ,<,\geq ,{\text{ and }}>} as defined previously, it can be observed that two elements x and y may stand in any of four mutually exclusive relationships to each other: either x < y, or x = y, or...
Standard examples of posets arising in mathematics include: 1. The real numbers, or in general any totally ordered set, ordered by the standard less-than-or-equalrelation ≤, is a partial order. 2. On the real numbers R {\displaystyle \mathbb {R} } , the usual less than relation < is a strict partial order. The same is also true of the usual greater...
The examples use the poset ( P ( { x , y , z } ) , ⊆ ) {\displaystyle ({\mathcal {P}}(\{x,y,z\}),\subseteq )} consisting of the set of all subsets of a three-element set { x , y , z } , {\displaystyle \{x,y,z\},} ordered by set inclusion (see Fig. 1). 1. a is related to b when a ≤ b. This does not imply that b is also related to a, because the rela...
Given two partially ordered sets (S, ≤) and (T, ≼), a function f : S → T {\displaystyle f:S\to T} is called order-preserving, or monotone, or isotone, if for all x , y ∈ S , {\displaystyle x,y\in S,} x ≤ y {\displaystyle x\leq y} implies f(x) ≼ f(y).If (U, ≲) is also a partially ordered set, and both f : S → T {\displaystyle f:S\to T} and g : T → U...
Sequence A001035 in OEIS gives the number of partial orders on a set of nlabeled elements: Note that S(n, k) refers to Stirling numbers of the second kind. The number of strict partial orders is the same as that of partial orders. If the count is made only up to isomorphism, the sequence 1, 1, 2, 5, 16, 63, 318, ... (sequence A000112 in the OEIS) i...
A poset P ∗ = ( X ∗ , ≤ ∗ ) {\displaystyle P^{*}=(X^{*},\leq ^{*})} is called a subposet of another poset P = ( X , ≤ ) {\displaystyle P=(X,\leq )} provided that X ∗ {\displaystyle X^{*}} is a subset of X {\displaystyle X} and ≤ ∗ {\displaystyle \leq ^{*}} is a subset of ≤ {\displaystyle \leq } . The latter condition is equivalent to the requiremen...
A partial order ≤ ∗ {\displaystyle \leq ^{*}} on a set X {\displaystyle X} is called an extension of another partial order ≤ {\displaystyle \leq } on X {\displaystyle X} provided that for all elements x , y ∈ X , {\displaystyle x,y\in X,} whenever x ≤ y , {\displaystyle x\leq y,} it is also the case that x ≤ ∗ y . {\displaystyle x\leq ^{*}y.} A lin...
Every poset (and every preordered set) may be considered as a category where, for objects x {\displaystyle x} and y , {\displaystyle y,} there is at most one morphism from x {\displaystyle x} to y . {\displaystyle y.} More explicitly, let hom(x, y) = {(x, y)} if x ≤ y (and otherwise the empty set) and ( y , z ) ∘ ( x , y ) = ( x , z ) . {\displayst...
Robert Francis Kennedy Jr. (born January 17, 1954), also known by his initials RFK Jr., is an American politician, environmental lawyer, anti-vaccine activist, and conspiracy theorist.He is the chairman and founder of Children's Health Defense, an anti-vaccine advocacy group that is a leading proponent of COVID-19 vaccine misinformation, and an independent candidate in the 2024 presidential ...
Ebola, also known as Ebola virus disease (EVD) and Ebola hemorrhagic fever (EHF), is a viral hemorrhagic fever in humans and other primates, caused by ebolaviruses.[1] Symptoms typically start anywhere between two days and three weeks after infection.[3] The first symptoms are usually fever, sore throat, muscle pain, and headaches.[1] These ...
