A-21 Motorway (Spain)
A- or a- may refer to: ;A-hyphen * A- (plane), a U.S. military aircraft prefix * Privative a, a prefix expressing negation * Copulative a, a prefix expressing unification ;A-minus * A−, a blood type in the ABO blood group system * A− (grade) This is a list of grading systems used by countries of the world, primarily within the fields of secondary education and university education, organized by continent with links to specifics in numerous entries. Africa Nigeria The choice of gr ..., an educational grade in the letter-grading system, above B+ but below A See also * Ā {{Disambiguation ... [...More Info...]       [...Related Items...]     OR:     [Wikipedia]   [Google]   [Baidu]   |
|
A- (plane)
An attack aircraft, strike aircraft, or attack bomber is a tactical military aircraft that has a primary role of carrying out airstrikes with greater precision than bombers, and is prepared to encounter strong low-level air defenses while pressing the attack.Mortensen 1987, pp. 24–25. This class of aircraft is designed mostly for close air support and naval air-to-surface missions, overlapping the tactical bomber mission. Designs dedicated to non-naval roles are often known as ground-attack aircraft.Gunston 2009, p. 73. Fighter aircraft often carry out the attack role, although they would not be considered attack aircraft ''per se'', although fighter-bomber conversions of those same aircraft would be considered part of the class. Strike fighters, which have effectively replaced the fighter-bomber and light bomber concepts, also differ little from the broad concept of an attack aircraft. The dedicated attack aircraft as a separate class existed primarily during and aft ... [...More Info...]       [...Related Items...]     OR:     [Wikipedia]   [Google]   [Baidu]   |
|
Privative A
An alpha privative or, rarely, privative a (from Latin ', from Ancient Greek ) is the prefix ''a-'' or ''an-'' (before vowels) that is used in Indo-European languages such as Sanskrit and Greek and in words borrowed therefrom to express negation or absence, for example the English words of greek origin '' atypical'', '' anesthetic'', and ''analgesic''. It is derived from a Proto-Indo-European syllabic nasal *', the zero ablaut grade of the negation *', i.e. /n/ used as a vowel. For this reason, it usually appears as ' before vowels (e.g. '' an-alphabetism'', '' an-esthesia'', '' an-archy''). It shares the same root with the Greek prefix ' or ', in Greek or , that is also privative (e.g. '). It is not to be confused with, among other things, an alpha copulative (e.g. ') or the prepositional component ' (i.e. the preposition ' with ecthlipsis or elision of its final vowel before a following vowel; e.g. '). Cognates Sanskrit The same prefix appears in Sanskrit, also as अ- be ... [...More Info...]       [...Related Items...]     OR:     [Wikipedia]   [Google]   [Baidu]   |
|
Copulative A
The copulative ''a'' (also ''a'' copulativum, ''a'' athroistikon) is the prefix ''ha-'' or ''a-'' expressing unity in Ancient Greek, derived from Proto-Indo-European *''sm̥-'', cognate to English ''same'' (see also Symbel).. An example is ''a-delphos'' "brother", from *''sm̥-gwelbhos'' literally "from the ''same'' womb" (compare Delphi). In Proto-Greek, ''s'' at the beginning of a word became ''h'' by debuccalization and syllabic ''m̥'' became ''a'', giving ''ha-''. The initial ''h'' was sometimes lost by psilosis or Grassmann's law. Cognate forms in other languages preserve the ''s'': for example, the Sanskrit prefix ''saṃ-'' in the name of the language, ''saṃ-s-kṛtā'' "put together". Less exact cognates include English ''same'' and ''some'', and Latin ''simul'' "at the same time" and ''similis'' "similar". Other words in Greek are related, including ''háma'' "at the same time", ''homós'' "same", and ''heís'' "one" (from )., , . See also * Privative a An alpha ... [...More Info...]       [...Related Items...]     OR:     [Wikipedia]   [Google]   [Baidu]   |
|
ABO Blood Group System
The ABO blood group system is used to denote the presence of one, both, or neither of the A and B antigens on erythrocytes. For human blood transfusions, it is the most important of the 43 different blood type (or group) classification systems currently recognized by the International Society of Blood Transfusions (ISBT) as of June 2021. A mismatch (very rare in modern medicine) in this, or any other serotype, can cause a potentially fatal adverse reaction after a transfusion, or an unwanted immune response to an organ transplant. The associated anti-A and anti-B antibodies are usually IgM antibodies, produced in the first years of life by sensitization to environmental substances such as food, bacteria, and viruses. The ABO blood types were discovered by Karl Landsteiner in 1901; he received the Nobel Prize in Physiology or Medicine in 1930 for this discovery. ABO blood types are also present in other primates such as apes and Old World monkeys. History Discovery The ABO ... [...More Info...]       [...Related Items...]     OR:     [Wikipedia]   [Google]   [Baidu]   |
|
A− (grade)
This is a list of grading systems used by countries of the world, primarily within the fields of secondary education and university education, organized by continent with links to specifics in numerous entries. Africa Nigeria The choice of grading system at Nigerian schools depends on the institution and sometimes on the faculty of the institution. In addition, grading scales at university-level institutions have changed frequently. Grading scales can be 1 to 8, 1 to 4, or A through G, where A is on a 4.0 scale or on a 5.0 scale. The most common scale is now 1 to 7, with 9 being the highest grade obtained. In addition, degrees are awarded in a Class, depending on the grades received. Degrees may be awarded in the First Class, Second Class (Upper Division), Second Class (Lower Division), Third Class, and Pass Class. Grading scales for secondary certificates are standard. Below is the grading system of Nigerian universities: South Africa In South Africa, some universities fo ... [...More Info...]       [...Related Items...]     OR:     [Wikipedia]   [Google]   [Baidu]   |