Misplaced Pages

#349650

48-486: References can take on many forms, including: a thought, a sensory perception that is audible ( onomatopoeia ), visual (text), olfactory , or tactile, emotional state , relationship with other, spacetime coordinates, symbolic or alpha-numeric , a physical object, or an energy projection. In some cases, methods are used that intentionally hide the reference from some observers, as in cryptography . References feature in many spheres of human activity and knowledge, and

96-561: A data dictionary . The adjective 'referential' describes the action that a foreign key performs, 'referring' to a linked column in another table. In simple terms, 'referential integrity' guarantees that the target 'referred' to will be found. A lack of referential integrity in a database can lead relational databases to return incomplete data, usually with no indication of an error. An inclusion dependency over two (possibly identical) predicates R {\displaystyle R} and S {\displaystyle S} from

144-582: A clinical setting, this management is offered by otologists and audiologists . Hearing loss is associated with Alzheimer's disease and dementia with a greater degree of hearing loss tied to a higher risk. There is also an association between type 2 diabetes and hearing loss . Hearing threshold and the ability to localize sound sources are reduced underwater in humans, but not in aquatic animals, including whales, seals, and fish which have ears adapted to process water-borne sound. Not all sounds are normally audible to all animals. Each species has

192-473: A column (or a group of columns) in another table (the referenced table) by using a foreign key . The referenced column(s) in the referenced table must be under a unique constraint, such as a primary key . Also, self-references are possible (not fully implemented in MS SQL Server though ). On inserting a new row into the referencing table, the relational database management system (RDBMS) checks if

240-475: A greater state of immediate awareness. However, it can also lead to circular reasoning , preventing evolution of thought. According to Perceptual Control Theory (PCT), a reference condition is the state toward which a control system's output tends to alter a controlled quantity. The main proposition is that "All behavior is oriented all of the time around the control of certain quantities with respect to specific reference conditions." In academics and scholarship,

288-497: A measure as employing an anechoic chamber , which absorbs nearly all sound. Another means is the use of devices such as earplugs , which are inserted into the ear canal to block noise, or earmuffs , objects designed to cover a person's ears entirely. The loss of hearing, when it is caused by neural loss, cannot presently be cured. Instead, its effects can be mitigated by the use of audioprosthetic devices, i.e. hearing assistive devices such as hearing aids and cochlear implants . In

336-501: A previous word, the previous word is called the " antecedent ". Gottlob Frege argued that reference cannot be treated as identical with meaning : " Hesperus " (an ancient Greek name for the evening star) and " Phosphorus " (an ancient Greek name for the morning star) both refer to Venus , but the astronomical fact that '"Hesperus" is "Phosphorus"' can still be informative, even if the "meanings" of "Hesperus" and "Phosphorus" are already known. This problem led Frege to distinguish between

384-474: A program to directly access the particular data item. Most programming languages support some form of reference. For the specific type of reference used in the C++ language, see reference (C++) . The notion of reference is also important in relational database theory ; see referential integrity . References to many types of printed matter may come in an electronic or machine-readable form. For books, there exists

432-438: A range of normal hearing for both amplitude and frequency . Many animals use sound to communicate with each other, and hearing in these species is particularly important for survival and reproduction. In species that use sound as a primary means of communication, hearing is typically most acute for the range of pitches produced in calls and speech. Frequencies capable of being heard by humans are called audio or sonic. The range

480-424: A record that contains a value referred to by a foreign key in another table would break referential integrity. Some relational database management systems (RDBMS) can enforce referential integrity, normally either by deleting the foreign key rows as well to maintain integrity, or by returning an error and not performing the delete. Which method is used may be determined by a referential integrity constraint defined in

528-450: A reference or bibliographical reference is a piece of information provided in a footnote or bibliography of a written work such as a book, article, essay, report, oration or any other text type , specifying the written work of another person used in the creation of that text. A bibliographical reference mostly includes the full name of the author , the title of their work and the year of publication. The primary purpose of references

SECTION 10

#1732773131350

576-563: A schema is written R [ A 1 , . . . , A n ] ⊆ S [ B 1 , . . . , B n ] {\displaystyle R[A_{1},...,A_{n}]\subseteq S[B_{1},...,B_{n}]} , where the A i {\displaystyle A_{i}} , B i {\displaystyle B_{i}} are distinct attributes (column names) of R {\displaystyle R} and S {\displaystyle S} . It implies that

624-409: A small air-filled chamber that is located medial to the eardrum. Within this chamber are the three smallest bones in the body, known collectively as the ossicles which include the malleus, incus, and stapes (also known as the hammer, anvil, and stirrup, respectively). They aid in the transmission of the vibrations from the eardrum into the inner ear, the cochlea . The purpose of the middle ear ossicles

672-411: A surrounding medium. The academic field concerned with hearing is auditory science . Sound may be heard through solid , liquid , or gaseous matter. It is one of the traditional five senses . Partial or total inability to hear is called hearing loss . In humans and other vertebrates, hearing is performed primarily by the auditory system : mechanical waves , known as vibrations, are detected by

720-720: Is a particular form of tuple-generating dependency (TGD) where in both the sides of the rule there is only one relational atom. In first-order logic it is expressible as ∀ x → , y → . ( R ( x → , y → ) → ∃ z → . S ( x → , z → ) ) {\displaystyle \forall {\vec {x}},{\vec {y}}.(R({\vec {x}},{\vec {y}})\rightarrow \exists {\vec {z}}.S({\vec {x}},{\vec {z}}))} , where x → {\displaystyle {\vec {x}}}

768-462: Is not directly coupled with frequency range. Georg Von Békésy in 1929 identifying sound source directions suggested humans can resolve timing differences of 10μs or less. In 1976 Jan Nordmark's research indicated inter-aural resolution better than 2μs. Milind Kuncher's 2007 research resolved time misalignment to under 10μs. Even though they do not have ears, invertebrates have developed other structures and systems to decode vibrations traveling through

816-411: Is similarly accessible. In art , a reference is an item from which a work is based. This may include: Another example of reference is samples of various musical works being incorporated into a new one. Hearing (sense) Hearing , or auditory perception , is the ability to perceive sounds through an organ, such as an ear , by detecting vibrations as periodic changes in the pressure of

864-430: Is the use of devices designed to prevent noise-induced hearing loss (NIHL), a type of post-lingual hearing impairment . The various means used to prevent hearing loss generally focus on reducing the levels of noise to which people are exposed. One way this is done is through environmental modifications such as acoustic quieting , which may be achieved with as basic a measure as lining a room with curtains , or as complex

912-532: Is the vector (whose size is n {\displaystyle n} ) of variables shared by R {\displaystyle R} and S {\displaystyle S} , and no variable appears multiple times neither in the TGD's body nor in its head. Logical implication between inclusion dependencies can be axiomatized by inference rules and can be decided by a PSPACE algorithm. The problem can be shown to be PSPACE-complete by reduction from

960-580: Is to allow readers to examine the sources of a text, either for validity or to learn more about the subject. Such items are often listed at the end of a work in a section marked References or Bibliography . References are particularly important as for the use of citations , since copying of material by another author without proper reference and / or without required permissions is considered plagiarism , and may be tantamount to copyright infringement , which can be subject to legal proceedings . A reference section contains only those works indeed cited in

1008-405: Is to overcome the impedance mismatch between air waves and cochlear waves, by providing impedance matching . Also located in the middle ear are the stapedius muscle and tensor tympani muscle , which protect the hearing mechanism through a stiffening reflex. The stapes transmits sound waves to the inner ear through the oval window , a flexible membrane separating the air-filled middle ear from

SECTION 20

#1732773131350

1056-494: Is typically considered to be between 20 Hz and 20,000 Hz. Frequencies higher than audio are referred to as ultrasonic , while frequencies below audio are referred to as infrasonic . Some bats use ultrasound for echolocation while in flight. Dogs are able to hear ultrasound, which is the principle of 'silent' dog whistles . Snakes sense infrasound through their jaws, and baleen whales , giraffes , dolphins and elephants use it for communication. Some fish have

1104-563: The ISBN and for journal articles, the Digital object identifier (DOI) is gaining relevance. Information on the Internet may be referred to by a Uniform Resource Identifier (URI) . In terms of mental processing, a self-reference is used in psychology to establish identification with a mental state during self-analysis. This seeks to allow the individual to develop own frames of reference in

1152-407: The agent (actor) and patient (acted on), as in "The man washed himself", the theme and recipient, as in "I showed Mary to herself", or various other possible combinations. In computer science , references are data types that refer to an object elsewhere in memory and are used to construct a wide variety of data structures , such as linked lists . Generally, a reference is a value that enables

1200-452: The basilar membrane , a structure that vibrates when waves from the middle ear propagate through the cochlear fluid – endolymph . The basilar membrane is tonotopic , so that each frequency has a characteristic place of resonance along it. Characteristic frequencies are high at the basal entrance to the cochlea, and low at the apex. Basilar membrane motion causes depolarization of the hair cells , specialized auditory receptors located within

1248-423: The ear and transduced into nerve impulses that are perceived by the brain (primarily in the temporal lobe ). Like touch , audition requires sensitivity to the movement of molecules in the world outside the organism. Both hearing and touch are types of mechanosensation . There are three main components of the human auditory system : the outer ear, the middle ear, and the inner ear. The outer ear includes

1296-506: The medial geniculate nucleus , a part of the thalamus where sound information is relayed to the primary auditory cortex in the temporal lobe . Sound is believed to first become consciously experienced at the primary auditory cortex . Around the primary auditory cortex lies Wernickes area , a cortical area involved in interpreting sounds that is necessary to understand spoken words. Disturbances (such as stroke or trauma ) at any of these levels can cause hearing problems, especially if

1344-413: The pinna , the visible part of the ear, as well as the ear canal , which terminates at the eardrum , also called the tympanic membrane. The pinna serves to focus sound waves through the ear canal toward the eardrum. Because of the asymmetrical character of the outer ear of most mammals, sound is filtered differently on its way into the ear depending on the location of its origin. This gives these animals

1392-419: The sense and reference of a word. The very concept of the linguistic sign is the combination of content and expression, the former of which may refer entities in the world or refer more abstract concepts, e.g. thought. Certain parts of speech exist only to express reference, namely anaphora such as pronouns . The subset of reflexives expresses co-reference of two participants in a sentence. These could be

1440-439: The 19th century. In patent law, a reference is a document that can be used to show the state of knowledge at a given time and that therefore may make a claimed invention obvious or anticipated . Examples of references are patents of any country, magazine articles, Ph.D. theses that are indexed and thus accessible to those interested in finding information about the subject matter, and to some extent Internet material that

1488-406: The ability to hear more sensitively due to a well-developed, bony connection between the ear and their swim bladder. This "aid to the deaf" for fishes appears in some species such as carp and herring . Human perception of audio signal time separation has been measured to less than 10 microseconds (10μs). This does not mean that frequencies above 100 kHz are audible, but that time discrimination

Reference - Misplaced Pages Continue

1536-408: The ability to localize sound vertically . The eardrum is an airtight membrane, and when sound waves arrive there, they cause it to vibrate following the waveform of the sound. Cerumen (ear wax) is produced by ceruminous and sebaceous glands in the skin of the human ear canal, protecting the ear canal and tympanic membrane from physical damage and microbial invasion. The middle ear consists of

1584-481: The acceptance problem for a linear bounded automaton . However, logical implication between dependencies that can be inclusion dependencies or functional dependencies is undecidable by reduction from the word problem for monoids . Declarative referential integrity (DRI) is one of the techniques in the SQL database programming language to ensure data integrity. A table (called the referencing table) can refer to

1632-567: The air, or “sound”. Charles Henry Turner was the first scientist to formally show this phenomenon through rigorously controlled experiments in ants. Turner ruled out the detection of ground vibration and suggested that other insects likely have auditory systems as well. Many insects detect sound through the way air vibrations deflect hairs along their body. Some insects have even developed specialized hairs tuned to detecting particular frequencies, such as certain caterpillar species that have evolved hair with properties such that it resonates most with

1680-414: The cochlea travels via the auditory nerve to the cochlear nucleus in the brainstem . From there, the signals are projected to the inferior colliculus in the midbrain tectum . The inferior colliculus integrates auditory input with limited input from other parts of the brain and is involved in subconscious reflexes such as the auditory startle response . The inferior colliculus in turn projects to

1728-723: The disturbance is bilateral . In some instances it can also lead to auditory hallucinations or more complex difficulties in perceiving sound. Hearing can be measured by behavioral tests using an audiometer . Electrophysiological tests of hearing can provide accurate measurements of hearing thresholds even in unconscious subjects. Such tests include auditory brainstem evoked potentials (ABR), otoacoustic emissions (OAE) and electrocochleography (ECochG). Technical advances in these tests have allowed hearing screening for infants to become widespread. Hearing can be measured by mobile applications which includes audiological hearing test function or hearing aid application . These applications allow

1776-418: The entered key value exists in the referenced table. If not, no insert is possible. It is also possible to specify DRI actions on UPDATE and DELETE , such as CASCADE (forwards a change/delete in the referenced table to the referencing tables), NO ACTION (if the specific row is referenced, changing the key is not allowed) or SET NULL / SET DEFAULT (a changed/deleted key in the referenced table results in setting

1824-399: The fluid-filled inner ear. The round window , another flexible membrane, allows for the smooth displacement of the inner ear fluid caused by the entering sound waves. The inner ear consists of the cochlea , which is a spiral-shaped, fluid-filled tube. It is divided lengthwise by the organ of Corti , which is the main organ of mechanical to neural transduction . Inside the organ of Corti is

1872-617: The main text of a work. In contrast, a bibliographical section often contains works not cited by the author, but used as background reading or listed as potentially useful to the reader. Keeping a diary allows an individual to use references for personal organization, whether or not anyone else understands the systems of reference used. However, scholars have studied methods of reference because of their key role in communication and co-operation between different people, and also because of misunderstandings that can arise. Modern academic study of bibliographical references has been developing since

1920-422: The organ of Corti. While the hair cells do not produce action potentials themselves, they release neurotransmitter at synapses with the fibers of the auditory nerve , which does produce action potentials. In this way, the patterns of oscillations on the basilar membrane are converted to spatiotemporal patterns of firings which transmit information about the sound to the brainstem . The sound information from

1968-404: The person John. The word "it" refers to some previously specified object. The object referred to is called the referent of the word. Sometimes the word-object relation is called " denotation "; the word denotes the object. The converse relation, the relation from object to word, is called " exemplification "; the object exemplifies what the word denotes. In syntactic analysis, if a word refers to

Reference - Misplaced Pages Continue

2016-403: The referenced value must exist. For referential integrity to hold in a relational database, any column in a base table that is declared a foreign key can only contain either null values or values from a parent table's primary key or a candidate key . In other words, when a foreign key value is used it must reference a valid, existing primary key in the parent table. For instance, deleting

2064-400: The sense of "connect to" or "link to", as in the meanings of reference described in this article. Another sense is "consult"; this is reflected in such expressions as reference work , reference desk , job reference , etc. In semantics , reference is generally construed as the relationships between nouns or pronouns and objects that are named by them. Hence, the word "John" refers to

2112-483: The sound of buzzing wasps, thus warning them of the presence of natural enemies. Some insects possess a tympanal organ . These are "eardrums", that cover air filled chambers on the legs. Similar to the hearing process with vertebrates, the eardrums react to sonar waves. Receptors that are placed on the inside translate the oscillation into electric signals and send them to the brain. Several groups of flying insects that are preyed upon by echolocating bats can perceive

2160-509: The term adopts shades of meaning particular to the contexts in which it is used. Some of them are described in the sections below. The word reference is derived from Middle English referren , from Middle French référer , from Latin referre , "to carry back", formed from the prefix re - and ferre , "to bear". A number of words derive from the same root, including refer , referee , referential , referent , referendum . The verb refer (to) and its derivatives may carry

2208-463: The tuples of values appearing in columns A 1 , . . . , A n {\displaystyle A_{1},...,A_{n}} for facts of R {\displaystyle R} must also appear as a tuple of values in columns B 1 , . . . , B n {\displaystyle B_{1},...,B_{n}} for some fact of S {\displaystyle S} . Such constraint

2256-416: The ultrasound emissions this way and reflexively practice ultrasound avoidance . Referential integrity Referential integrity is a property of data stating that all its references are valid. In the context of relational databases , it requires that if a value of one attribute (column) of a relation (table) references a value of another attribute (either in the same or a different relation), then

2304-498: The user to measure hearing thresholds at different frequencies ( audiogram ). Despite possible errors in measurements, hearing loss can be detected. There are several different types of hearing loss: conductive hearing loss , sensorineural hearing loss and mixed types. Recently, the term of Aural Diversity has come into greater use, to communicate hearing loss and differences in a less negatively-associated term. There are defined degrees of hearing loss: Hearing protection

#349650