By supposing the retardation to vary uniformly and continuously we, fall upon the case of an ordinary prism: but there;, is then no diffraction spectrum in the usual sense.
The rate of diminution of amplitude expressed by the coefficient a in the index of the exponential is here greater than the coefficient b expressing the retardation of phase by a small term depending on the emissivity h.
If the retardation be too little, the overlapping of the processions is incomplete, so that besides the procession of half period there are residues of the original processions of full period.
Mag., 1837, 10, p. 364) was that any ray which suffered in traversing the plate a retardation of an odd number of half wave-lengths would be extinguished, and that thus the spectrum would be seen interrupted by a number of dark bars.
Such a conclusion would be in the face of the principle of energy, which teaches plainly that the retardation in question leaves the aggregate brightness unaltered.
The expression (5) gives the illumination at due to that part of the complete image whose geometrical focus is at =o, the retardation for this component being R.
E is then the co-ordinate relatively to 0 of any focal point 0' for which the retardation is R; and the required result is obtained by simply integrating (5) with respect to from - cc to +oo.
The consequences must depend upon the amount of the retardation.
The formation of black bands is thus explained, and it requires that the plate be introduced upon one particular side, and that the amount of the retardation be adjusted to a particular value.
If the plate be introduced upon the other side, so as to retard the procession originally in arrear, there is no overlapping, whatever may be the amount of retardation.
Taking as the standard phase that of the secondary wave from A, we may represent the effect of PQ by cos 27r (_) .ds, where, l = BP - AP is the retardation at B of the wave from P relatively to that from A.
Some phenomena of retardation in the production of the effect had led Sir G.
also in air for very low velocities, but, where the velocities are high, the retardation is great, the projectile takes longer to traverse each succeeding space, and consequently the time of flight for any range is longer; the axis must therefore be directed still higher above the point to be struck.
The position of these fringes will depend on the total retardation in time of the one beam with respect to the other; and thus it might be expected to vary with the direction of the earth's motion,.
In any region of velocity where it is possible to represent p with sufficient accuracy by an empirical formula composed of a single power of v, say v m, the integration can be effected which replaces the summation in (to), (16), and (24); and from an analysis of the Krupp experiments Colonel Zabudski found the most appropriate index m in a region of velocity as given in the following table, and the corresponding value of gp, denoted by f (v)or v m lk or its equivalent Cr, where r is the retardation.
For a time the retardation of the normal rate of increase among the native population was concealed from view by the extraordinary immigration.
The superintendent of the Ninth Census, 1870, presented a computation 01 the effects of this causefirst, through direct losses, by wounds or disease, either in actual service of the army or navy, or in a brief term following discharge; secondly, through the retardation of the rate of increase in the colored element, due to the privations, exposures and excesses attendant upon emancipation; thirdly, through the check given to immigration by the existence of war, the fear of conscription, and the apprehension abroad of results prejudicial to the national welfare.
The glochidium is formed by the precocious development of the anterior adductor and the retardation of all the other organs except the shell.
Tyndall's own summary of the course of research on the subject was as follows: The idea of semi-fluid motion belongs entirely to Rendu; the proof of the quicker central flow belongs in part to Rendu, but almost wholly to Agassiz and Forbes; the proof of the retardation of the bed belongs to Forbes alone; while the discovery of the locus of the point of maximum motion belongs, I suppose, to me.
The heat evolved by this process of solidification retards the fall of temperature; but after this the rate of cooling remains regular until T (750°) on the line Sa (Ar 3) is reached, when a second retardation occurs, due to the heat liberated by the passage within the pasty mass of part of the iron and carbon from a state of mere solution to that of definite combination in the ratio Fe 3 C, forming microscopic particles of cementite, while the remainder of the iron and carbon continue dissolved in each other as austenite.
At the second retardation, K" (Ar2, about 770°) this ferrite changes to the normal magnetic a-ferrite, so that the mass as a whole becomes magnetic. Moreover, the envelopes of ferrite which began forming at Ar 3 continue to broaden by the accession of more and more ferrite born from the austenite progressively as the temperature sinks, till, by the time when Ar t (about 690°) is reached, so much free ferrite has been formed that the remaining mother-metal has been enriched to the composition of hardenite, i.e.
One necessary effect of the tidal retardation of the earth's rotation is gradually to increase this length.
On the voyage he noticed the retardation of the pendulum in approaching the equator; and during his stay on the island he observed, on the 7th of November 1677, a transit of Mercury, which suggested to him the important idea of employing similar phenomena for determining the sun's distance.
of e~~ the variation of each co-ordinate is simple-harmonic, with the prescribed period, but there is a retardation of phase as compared with the force.
An excess of the effort exerted on any piece, above that which is necessary to balanoe the resistance, is accompanied with acceleration; a deficiency of the effort, with retardation.
An excess of resistance above effort involves an excess of work performed above energy expended; that excess of work is performed by means of the retardation of the machinery.
When a machine undergoes alternate acceleration and retardation, so that at certain instants of time, occurring at the end of intervals called periods or cycles, it returns to its original speed, then in each of those periods or cycles the alternate excesses of energy and of work neutralize each other; and at the end of each cycle the principle of the equality of energy and work stated in 87, with all, its consequences, is verified exactly as in the case of machines of uniform speed.
At intermediate instants, however, other principles have also to be taken into account, which are deduced from the second law of motion, as applied to direct deviation, or acceleration and retardation.
Let e denote the quantity by which the energy exerted in each cycle of the working of the machine alternately exceeds and falls short of the work performed, and which has consequently to be alternately stored by acceleration and restored by retardation of the flywheel.
That, in spite of retardation and retrogression, the old order of ideas should have yielded to the new all over Europe, - that science should have won firm standing-ground, and political liberty should have struggled through those birth-throes of its origin, - was in the nature of things.
Before his death, however, the retardation of light in denser media was demonstrated by the experiments of H.
At the same time, the tendency to a retardation in the development of the posterior thoracic somites is very general in Malacostracan larvae, and may perhaps be correlated with the f
This is necessary in order that the down and up strokes may glide into each other in such a manner as to prevent jerking and unnecessary retardation."
The equation of light is the time taken by light to traverse the sun's mean distance from the earth; it can be found by the acceleration or retardation of the eclipses of Jupiter's satellites according as Jupiter is approaching opposition or conjunction with the sun; a recent analysis shows that its value is 498.6", which leads to the same value of the parallax as above, but the internal discrepancies of the material put its authority upon a much lower level.
The term "perfect gas" is applied to an imaginary substance in which there is no frictional retardation of molecular motion; or, in other words, the time during which any molecule is influenced by other molecules is infinitesimally small compared with the time during which it traverses its mean free path.
The smaller the angle which the orbit of the moon, when near the point of rising, makes with the horizon the less will be the retardation.
In 1856 William Ferrel showed that the action of the moon on the ocean tidal waves would result in a retardation of the earth's rotation, a result, at first unnoticed, which was independently reached a few years later by Delaunay.
The amount of retardation does not admit of accurate computation, owing to the uncertainty both as to the amount of the oceanic friction from which it arises and of the exact height and form of the tidal wave, the action of the moon on which produces the effect.
This is only 2.4" larger than the theoretical value, and it seems difficult to suppose that the effect of the tidal retardation can be as small as this.
This suggests that the retardation may be in great part compensated by some accelerating cause, the existence of which is not yet well established.
a crystalline plate of such a thickness that it introduces a relative retardation of a quarter of a wave between the component streams within it.
Since a beam of common light can be resolved into plane polarized streams and these on recomposition give a stream with properties indistinguishable from those of common light, whatever their relative retardation may be, it is natural to assume that an analytical representation of common light can be obtained in which no longitudinal vector occurs.
Let a, 0, be the angles that the primitive and final planes of polarization and the plane of polarization of the quicker wave within the plate make with a fixed plane, and let be the relative retardation of phase of the two streams on emergence from the plate for light of period T.
In the former case the retardation of phase varies so little with the period that the intensity is nearly the same for all colours; in the latter case it alters so rapidly that for a small change in the period the intensity passes from a maximum or a minimum, and consequently so many constituents of the light are weakened and these are so close to one another in frequency, that the light presents to the eye the appearance of being white.
When the retardation of phase for light of mean period is it or a small multiple of it a crystalline plate placed between a crossed polarizer and analyser exhibits in white light a distinctive greyish violet colour, known as a sensitive tint from the fact that it changes rapidly to blue or red, when the retardation is very slightly increased or diminished.
In monochromatic light, then, the interference pattern is characterized by three systems of curves: the curves of constant retardation p = const.; the lines of like polarization = const.; the curves of constant intensity I = const.
These conditions define two systems of curves called respectively the principal curves of constant retardation and the principal lines of like polarization, these latter lines dividing the field into regions in which the intensity is alternately greater and less than the fundamental intensity.
The determination of the curves of constant retardation depends upon expressing the retardation in terms of the optical constants of the crystal, the angle of incidence and the azimuth of the plane of incidence.
growth retardation, again at maternally toxic doses.
intrauterine growth retardation) are more frequently born to mothers with coeliac disease.
Then McBride said his research showed that Debendox was also responsible for causing mental retardation.
In particular, it targets children with developmental disabilities including mental retardation, autism, cerebral palsy, learning difficulties and epilepsy.
When speaking with someone who has mental retardation, keep your language simple and make your concepts clear.
At the same time the employers and fellow employees become sensitized to individuals with mild to moderate mental retardation.
mental retardation associated with language delays, autism, and cerebral palsy.
Subsequently, five further families have been identified, some of which also include individuals with X-linked mental retardation without infantile spasms 48-52.
Other research areas include dyslexia and dynamic assessment in persons with severe mental retardation.
Teaching adolescents with mild mental retardation to make decisions in leisure through the use of self-control techniques.
Attention deficit hyperactivity disorder among adults with severe and profound mental retardation.
mental retardation in children at risk ' by H.L. Garber.
mental retardation in the human population.
phenylalanine in the body build up to toxic levels, causing mental retardation and organ damage.
psychopathology in people with mental retardation.
retardation associated with language delays, autism, and cerebral palsy.
There is a case for treatment of all SLE pregnancies with aspirin to prevent fetal growth retardation.
Babies who are small for their age in the womb (intrauterine growth retardation) are more frequently born to mothers with coeliac disease.
Administration of Tenormin to pregnant women in the management of mild to moderate hypertension has been associated with intra-uterine growth retardation.
For pupils with mental retardation there are nearly no changes.
retardation plate slot at 45 degrees to this.
For the majority the cause of growth retardation is not known.
This interactive tutorial explores how varying the amount of bias retardation can affect the appearance and level of staining achieved in the specimen image.
Cholesterol acetate, crossed polars and lambda retardation plate.
retardation in affected children, although it does not restore hearing.
retardation in growth can occur, which may result in shortened femora.
retardation of grain growth were investigated, all based on the sol-gel route.
retardation of the economic development of Spain inevitably weakened the centralist tendencies inherent in capitalism.
savior syndrome is more a danger than retardation.
Near-term rat fetuses showed growth retardation, again at maternally toxic doses.
(14) S is the retardation due to the particles, and we have I =nTdx(D' - D)/2D.
By dividing a line into two halves the working speed will be dependent upon the KR of the longest half, and as both K and R are directly proportional to the length of the line, the KR product for the half of a circuit is but one quarter that of the whole length of the circuit, and the retardation is correspondingly small.
per hour in 13 seconds, the rate at which work would have to be absorbed by the brake blocks would represent 237 H.P. This is lost in heat produced by the friction between the brake blocks and the wheels, though in some systems of electric driving some of the energy stored in the train may be returned to the central station during retardation.
This retardation was still more pronounced in the case of tungsten-steel, which lost its magnetism at 910Ã‚° and remained nonmagnetic till it was cooled to 570Ã‚°, a difference of 240Ã‚°.
In virtue of the general law that the reduced optical path is stationary in value, this retardation may be calculated without allowance for the different paths pursued on the farther side of L, L', so that the value is simply PL - PL'.
In the case of oblique reflection at an angle cb, the error of retardation due to an elevation BD (fig.
'; To obtain such it would be necessary that the retardation should gradually alter by a wavelength in passing over any element of the grating, and then fall back to its previous value, thus springing suddenly over a wave-length (Phil.
Moreover by (2) and (31) the retardation of phase of the elementary vibration from PQ (fig.
Others he treated very superficially, and in none of his experiments apparently did he attend to the diminution of efflux arising from the contraction of the liquid vein, when the orifice is merely a perforation in a thin plate; but he appears to have been the first who attempted to ascribe the discrepancy between theory and experiment to the retardation of the water's velocity through friction.
The amount, however, still depends on the time of flight, as the retardation of the air to the falling velocity may be neglected in the case of flat trajectory guns.
Formulae of the calculus of finite differences enable us from the chronograph records to infer the velocity and retardation of the shot, and thence the resistance of the air.
His " law of acceleration " together with the complementary " law of retardation," or the slowing up in the development of certain characters (first propounded by E.
Cope's philosophic contributions to palaeontology began in 1868 (see essays in The Origin of the Fittest, New York, 1887, and The Primary Factors of Organic Evolution, Chicago, 1896) with the independent discovery and demonstration among vertebrates of the laws of acceleration and retardation.
The evolution consists first in progressive increase in size; second, in the acceleration of the median digit and retardation of the lateral digits, the latter becoming more and more elevated from the ground until finally in Equus (6) they are the lateral splints, which in the embryonic condition have vestigial cartilages attached representing the last traces of the lateral phalanges.
- LAW OF Acceleration And Retardation Illustrated In The Evolution Of The Hind Feet Of The Horse.
The above law of gradual evolution is perfectly consistent with a second principle, namely, that at certain times evolution is much more rapid than at others, and that organisms are accelerated or retarded in development in a manner broadly analogous to the acceleration or retardation of separate organs.
(See Retardation above.) V.
The heat evolved by this process of solidification retards the fall of temperature; but after this the rate of cooling remains regular until T (750Ã‚°) on the line Sa (Ar 3) is reached, when a second retardation occurs, due to the heat liberated by the passage within the pasty mass of part of the iron and carbon from a state of mere solution to that of definite combination in the ratio Fe 3 C, forming microscopic particles of cementite, while the remainder of the iron and carbon continue dissolved in each other as austenite.
At the second retardation, K" (Ar2, about 770Ã‚°) this ferrite changes to the normal magnetic a-ferrite, so that the mass as a whole becomes magnetic. Moreover, the envelopes of ferrite which began forming at Ar 3 continue to broaden by the accession of more and more ferrite born from the austenite progressively as the temperature sinks, till, by the time when Ar t (about 690Ã‚°) is reached, so much free ferrite has been formed that the remaining mother-metal has been enriched to the composition of hardenite, i.e.
The retardation plate slot at 45 degrees to this.
Prompt diagnosis and treatment can prevent long-term growth retardation in affected children, although it does not restore hearing.
Additionally, retardation in growth can occur, which may result in shortened femora.
Experimental In this work, three methods for the retardation of grain growth were investigated, all based on the sol-gel route.
The cowboy savior syndrome is more a danger than retardation.
Psychomotor agitation or retardation: When you do manage to do anything, you can't do it as quickly as you used to.
Affected children have marked developmental and motor delays in the form of cerebral palsy and mental retardation may also be present.
Surviving infants with CMV may suffer from hearing problems (15%) or mental retardation (30%).
T. gondii infection of a fetus or newborn can also cause severe neurological impairment, blindness, mental retardation, and death.
Severe infections lead to seizure disorders, neurological disorders, abnormal muscle tone, deafness, partial or complete blindness caused by a condition called chorioretinitis, and mental retardation.
Afflicted children die in infancy or suffer damage to their central nervous systems that can result in physical and mental retardation.
Mental retardation is a developmental disability that first appears in children under the age of 18.
According to statistics made available by the Centers for Disease Control and Prevention in the 1990s, mental retardation occurs in 2.5 to 3 percent of the general population.
Mental retardation begins in childhood or adolescence before the age of 18.
A diagnosis of mental retardation is made if an individual has an intellectual functioning level well below average and significant limitations in two or more adaptive skill areas.
Mental retardation is defined as IQ score below 70 to 75.
Symptoms of mental retardation may appear at birth or later in childhood.
Some cases of mild mental retardation are not diagnosed before the child enters preschool.
There are four different degrees of mental retardation: mild, moderate, severe, and profound.
Their retardation is often caused by an accompanying neurological disorder.
The American Association on Mental Retardation (AAMR) has developed another widely accepted diagnostic classification system for mental retardation.
For children, the mental retardation rate is 11.4 per 1,000 and varies approximately nine fold, ranging from 3.2 in New Jersey to 31.4 in Alabama.
Low educational attainment was the most important correlate of mental retardation rates among adults.
Low IQ scores and limitations in adaptive skills are the hallmarks of mental retardation.
If retardation is caused by chromosomal or other genetic disorders, it is often apparent from infancy.
If retardation is caused by childhood illnesses or injuries, learning and adaptive skills that were once easy may suddenly become difficult or impossible to master.
In about 35 percent of cases, the cause of mental retardation cannot be found.
Biological and environmental factors that can cause mental retardation include genetics, prenatal illnesses and issues, childhood illnesses and injuries, and environmental factors.
About 5 percent of mental retardation is caused by hereditary factors.
Mental retardation may be caused by an inherited abnormality of the genes, such as fragile X syndrome.
Fragile X, a defect in the chromosome that determines sex, is the most common inherited cause of mental retardation.
Single gene defects such as phenylketonuria (PKU) and other inborn errors of metabolism may also cause mental retardation if they are not found and treated early.
An accident or mutation in genetic development may also cause retardation.
It is the most common genetic cause of mental retardation.
Drug abuse and cigarette smoking during pregnancy have also been linked to mental retardation.
Maternal infections and illnesses such as glandular disorders, rubella, toxoplasmosis, and cytomegalovirus infection may cause mental retardation.
When the mother has high blood pressure (hypertension) or blood poisoning (toxemia), the flow of oxygen to the fetus may be reduced, causing brain damage and mental retardation.
Birth defects that cause physical deformities of the head, brain, and central nervous system frequently cause mental retardation.
Hyperthyroidism, whooping cough, chickenpox, measles, and Hib disease (a bacterial infection) may cause mental retardation if they are not treated adequately.
An infection of the membrane covering the brain (meningitis) or an inflammation of the brain itself (encephalitis) cause swelling that in turn may cause brain damage and mental retardation.
Traumatic brain injury caused by a blow or a violent shake to the head may also cause brain damage and mental retardation in children.
Exposure to lead can also cause mental retardation.
If mental retardation is suspected, a comprehensive physical examination and medical history should be done immediately to discover any organic cause of symptoms.
If these conditions are discovered early, the progression of retardation can be stopped and, in some cases, partially reversed.
The symptoms of mental retardation are usually evident by a child's first or second year.
By the time a child reaches the age of two or three, retardation can be determined using physical and psychological tests.
Testing is important at this age if a child shows signs of possible retardation because alternate causes, such as impaired hearing, may be found and treated.
The level of training depends on the degree of retardation.
However, as of 2004, there is no cure for mental retardation.
A promising but controversial treatment for mental retardation involves stem cell research.
In the early 2000s scientists are exploring the potential of adult stem cells in treating mental retardation.
They have transplanted bone marrow cells into living embryos in the uteri of animals to approach congenital diseases, birth defects, and mental retardation.
Individuals with mild to moderate mental retardation are frequently able to achieve some self-sufficiency and to lead happy and fulfilling lives.
The outlook is less promising for those with severe to profound retardation.
The diseases that are usually associated with severe retardation may cause the shorter life span.
Immunization against diseases such as measles and Hib prevents many of the illnesses that can cause mental retardation.
Newborn screening and immediate treatment for PKU and hyperthyroidism can usually catch these disorders early enough to prevent retardation.
Good prenatal care can also help prevent retardation.
The sooner the diagnosis of mental retardation is made, the more the child can be helped.
Children with Down syndrome have varying degrees of mental retardation and may have heart defects.
Inborn errors of metabolism can cause brain damage and mental retardation if left untreated.
As a result, phenylalanine builds up in the body causing mental retardation and other neurological problems.
My Name Is Not Slow: Youth with Mental Retardation.
Wehmeyer, Michael L., et al. Teaching Students with Mental Retardation: Providing Access to the General Curriculum.
"Conceptions of Work among Adolescents and Young Adults with Mental Retardation."
Kerker, Bonnie D., et al. "Mental Health Disorders among Individuals with Mental Retardation: Challenges to Accurate Prevalence Estimates."
Hodapp. "Maternal Attribution of Child Noncompliance in Children with Mental Retardation: Down Syndrome versus Other Causes."
American Association on Mental Retardation. 444 North Capitol Street NW, Suite 846, Washington, DC 20001-1512.
The VABS assessment provides the information required for the diagnosis or evaluation of a wide range of disabilities, including mental retardation, developmental delays, functional skills impairment, and speech/language impairment.
Symptoms progress rapidly to seizures, difficulty swallowing, blindness, deafness, mental retardation, and paralysis.
Early symptoms include loss of vision and physical coordination, seizures, and mental retardation.
Children with A-T usually have normal or above normal intelligence, but some cases of mental retardation have been reported.
Other symptoms can include, delay in reaching developmental milestones, mental retardation, rapid head growth, and slowed growth of the rest of the body.
Medical care for children with macrocephaly focuses on management of specific symptoms such as developmental delays and mental retardation and treatment of the primary diagnosis responsible for the macrocephaly.
Canavan disease-A serious genetic disease more common in the Eastern European Jewish population that causes mental retardation and early death.
American Association on Mental Retardation 1719 Kalorama Road, NW Washington, DC 20009-2683.
Rubella causes severe birth defects (including heart defects, cataracts, deafness, and mental retardation) if a pregnant woman contracts it during the first three months of pregnancy.
Long-term problems following recovery from measles encephalitis may include seizures and mental retardation.
Some prenatal factors known to contribute to growth retardation include a variety of maternal health problems, including toxemia, kidney and heart disease, infections such as rubella and maternal malnutrition.
In addition to retarding growth, it can cause mental retardation if thyroid hormones are not administered in the first months of an infant's life.
Children with renal disease often experience growth retardation, especially if the condition is congenital.
A form of severe malnutrition called marasmus retards growth in all parts of the body, including the head (causing mental retardation as well).
Although the mental and emotional effects of the condition can be reversed with changes in environment, the growth retardation it causes is permanent.
On occasion, growth retardation may also be caused solely by emotional deprivation.
More than 150,000 children in the United States receive growth hormone therapy to remedy growth retardation caused by endocrine deficiencies.
Mental retardation can also affect the age at which children learn to talk.
There are many causes of mental retardation, including identified genetic syndromes such as Down syndrome, Williams syndrome, or fragile X syndrome.
Retardation can also be caused by damage to the fetus during pregnancy due to alcohol, drug abuse or toxicity, and disorders of the developing nervous system such as hydrocephalus.
Specific language impairment describes a condition of markedly delayed language development in the absence of any apparent handicapping conditions such as deafness, autism, or mental retardation.
A severe form of CP could involve significant muscle problems in all four limbs, mental retardation, seizures, and difficulties with vision, speech, and hearing.
About one third of individuals with CP have moderate-to-severe mental retardation, one third have mild mental retardation, and one third have normal intelligence.
The severe form of MPS II is associated with progressive mental retardation and physical disability, with most individuals dying before age 15.
Many children with MPS III develop seizures, sleeplessness, thicker skin, joint contractures, enlarged tongues, cardiomyopathy, behavior problems, and mental retardation.
Individuals with MPS IV appear healthy at birth but show skeletal deformities and growth retardation by age three.
In childhood, blood lead levels above 80 mg/dL generally indicate lead poisoning; however, significantly lower levels ( 30 mg/dL) can cause mental retardation and other cognitive and behavioral problems in affected children.
Although most individuals with spina bifida have normal intellectual function, learning disabilities or mental retardation occur in a minority.
The most common birth defects resulting from congenital rubella infection are eye defects such as cataracts, glaucoma, and blindness; deafness; congenital heart defects; and mental retardation.
About 33 to 50 percent of all tuberous sclerosis patients have problems such as learning disabilities, severe mental retardation, attention deficit disorder, obsessive-compulsive disorder, autism, aggression, rage, or self-harming behavior.
FAS is the leading known preventable cause of mental retardation and birth defects.
Learning disabilities or mental retardation may be diagnosed during this time.
Traditionally, IQ scores of 90-109 are considered average; scores below 70 indicate mental retardation.
Mental retardation usually refers to people with an IQ below 70.
Mental retardation affects roughly 1 percent of the U.S. population.
According to the U.S. Department of Education, about 11 percent of school-aged children were enrolled in special education programs for students with mental retardation.
There are four categories of mental retardation: mild, moderate, severe, and profound.
There are many different causes of mental retardation, both biological and environmental.
In about 5 percent of cases, retardation is transmitted genetically, usually through abnormalities in chromosomes, such as Down syndrome or fragile X syndrome.
Children with Down syndrome have both mental and motor retardation.
It is the most common form of inherited mental retardation.
There is no cure for autism or mental retardation.
These problems can include major health conditions including cerebral palsy, mental retardation, blindness, deafness, and diabetes.
Zinc deficiency has been associated with reduced growth and mental retardation.
In general, developmental delay, mental retardation, and vision and hearing impairment are common in those who have these disorders.
Less than 1 percent of the non-autistic population, including those with mental retardation and other developmental disorders, have savant syndrome.
Mental retardation accounts for more than 50 percent of language delays.
Language delay is usually more severe than other developmental delays in retarded children, and it is often the first noticeable symptom of mental retardation.
Mental retardation causes global language delay, including delayed auditory comprehension and use of gestures.
In general the severity of language delay depends on the severity of the mental retardation.
Generalized delay in all developmental milestones suggests mental retardation.
At other times, the parent may truly care about the child but lacks the ability or strength to adequately provide for the child's needs because handicapped by depression, drug abuse, mental retardation, or some other problem.
The term intrauterine growth retardation (also known as intrauterine growth restriction)(IUGR) is generically defined as a fetus who is at or below the tenth percentile in weight for its gestational age.
Fragile X syndrome, a genetic condition involving changes in the long arm of the X chromosome, is the most common form of inherited mental retardation.
Individuals with this condition have developmental delay, variable levels of mental retardation, and behavioral and emotional difficulties.
Generally, males are affected with moderate mental retardation (since they only have one X chromosome) and females with mild mental retardation.
Fragile X syndrome is the most common form of inherited mental retardation in the United States.
Females who inherit the full mutation have an approximately 30-50 percent risk of mental impairment, ranging from mild learning disability to mental retardation and behavioral problems.
The severity of mental impairment ranges from learning disabilities to severe mental retardation.
In females who carry a full mutation, the physical and behavioral features and mental retardation tend to be less severe.
Behavioral and developmental problems may indicate fragile X syndrome, particularly if there is a family history of mental retardation.
Hemoglobin H symptoms can also be a part of a unique condition called alpha thalassemia mental retardation syndrome.
Affected individuals have mild hemoglobin H disease, mild-to-moderate mental retardation, and characteristic facial features, as well as various other developmental processes that mimic hemoglobin H disease.
"Alpha-thalassemia Mental Retardation Syndrome, Nondeletion Type."
Children who survive infancy have profound mental retardation and may experience seizures.
Both forms of partial trisomy also result in severe mental retardation.
Those who do not die may experience permanent blindness, mental retardation, seizure disorders, or loss of motor control.
Autistic disorder, also referred to as autism, is characterized by moderate to severe communication, socialization, and behavioral problems, and in some children, mental retardation.
Congenital myotonic dystrophy is marked by severe weakness, poor sucking and swallowing responses, respiratory difficulty, delayed motor development, and mental retardation.
Individuals with mental retardation who function at or below an approximate cognitive level of 18 months may also be exempt from this diagnosis.
"Assessment of feeding and mealtime behavior problems in persons with mental retardation."
Infants with the disease are unable to process a certain type of fat which accumulates in nerve and brain cells, causing mental and physical retardation, and, finally, death.
A subtype, called Fukuyama CMD, also involves mental retardation.
In contrast, children with Fukuyama CMD are rarely able to walk and have severe mental retardation.
The primary symptom of untreated PKU, mental retardation, is the result of consuming foods that contain the amino acid phenylalanine, which is toxic to brain tissue.
Untreated PKU patients develop a broad range of symptoms related to severely impaired cognitive function, sometimes referred to as mental retardation.
In the early 1950s, researchers first demonstrated that phenylalanine-restricted diets could eliminate most of the typical PKU symptoms-except for mental retardation.
The causes for language problems have been linked to hearing, nerve, and muscle disorders; head injury; viral diseases; mental retardation; drug abuse; and cleft lips or palate.
It causes major physical abnormalities and severe mental retardation.
Treatment within the first few months of life can prevent mental retardation and physical abnormalities.
Cretinism-Severe hypothyroidism that is present at birth and characterized by severe mental retardation.
While it was once believed that all boys with Klinefelter syndrome were mentally retarded, doctors now know that the disorder can exist without retardation.
Boys with several extra X chromosomes have distinctive facial features, more severe retardation, deformities of bony structures, and even more disordered development of male features.
The Son-Rise program was created by Barry and Samahria Lyte Kaufman in the 1970s, as a means to teach their own son, who was diagnosed with autism and mental retardation.
The most common congenital defects are cataracts, heart disease, deafness, and mental retardation.
Down syndrome is a condition that includes mental retardation and a distinctive physical appearance linked to an abnormality of chromosome 21 (called trisomy 21).
Unfortunately, about 20 percent later develop severe hearing impairments and mental retardation.
Growth retardation, delayed puberty, or abnormal menstruations has also been reported in children and adolescents with Pattern II EG.
CMV interferes with normal fetal development and can cause mental retardation, blindness, deafness, or epilepsy in these infants.
Rubella infection during early pregnancy can pass through the placenta to the developing infant and cause serious birth defects, including heart abnormalities, mental retardation, blindness, and deafness.
Common disabilities include specific learning disabilities (e.g., dyslexia), speech or language impairment, mental retardation, and emotional disturbance.
They also have unusual facial features, poor muscle tone (hypotonia), small head size (microcephaly), and mental retardation.
Infants with cri du chat may also have congenital heart defects, language difficulties, delayed motor skill development, scoliosis, and varying degrees of mental retardation.
Mental retardation is present in all children with cri du chat, but the degree of mental retardation varies between children.
The extent of mental retardation and other symptoms depends on the site of the chromosomal deletions, with larger deletions resulting in more serious symptoms.
Before routine vaccination, Hib was the most common cause of bacterial meningitis and responsible for most of the cases of acquired mental retardation in the United States.
Untreated Menkes' disease is associated with mental retardation and death before three years of age.
Iodine deficiency during pregnancy can result in cretinism in newborns, involving mental retardation and a large tongue.
Symptoms of bipolar depressive episodes include low energy levels, feelings of despair, difficulty concentrating, extreme fatigue, and psychomotor retardation (slowed mental and physical capabilities).
Developmental delay/mental retardation: Seizures are responsible for learning difficulties in two out of three children with SWS.
Megalencephaly due to neurological or metabolic disease: Mental retardation, seizures.
The body's immune system is often weakened, behavioral development is slow, and mental retardation may occur.
Some children recover completely, while others may have a variety of lifelong impairments, including an inability to properly absorb nutrients in the intestines, as well as mental retardation.
In American Journal of Mental Retardation 109 (July 2004): 275-84.
In American Journal of Mental Retardation 107 (May 2002): 194-200.
Sometimes the term is used for mental retardation, which is not a delay in development but rather a permanent limitation.
Children with a diagnosis of mental retardation often have mixed or global development delays.
Children with a specific learning disability, like children with severe mental retardation or autism, may present with dissociation in developmental skills.
Beirne-Smith, Mary R., et al. Mental Retardation: An Introduction to Intellectual Disability.
However, a larger skin surface area to body weight ratio may make children more susceptible to adrenal gland problems such as growth retardation and delayed weight gain.
Continued feeding of milk products to the infant will lead to cirrhosis, cataracts, kidney failure, and mental retardation.
Isotretinoin can cause serious birth defects, including mental retardation and physical deformities.
Babies who survive pregnancy may develop kernicterus, which can lead to deafness, speech problems, cerebral palsy, or mental retardation.
Down syndrome is the most common cause of mental retardation and malformation in a newborn.
The level of mental retardation is considered to be mild-to-moderate in Down syndrome.
The severity of the retardation can also vary significantly.
Over the long term, lead poisoning in a child can lead to learning disabilities, behavioral problems, and even mental retardation.
Toxoplasma can cause birth defects including blindness, hearing loss, and mental retardation.
Drinking during pregnancy can lead to intrauterine growth retardation (IUGR).
Other neurological problems can include seizures, hyperactivity, and mental retardation.
Premature birth is associated with an increase in serious disabilities such as cerebral palsy, mental retardation, and vision or hearing loss.
The amino acid is either incompletely metabolized or improperly metabolized, with the resulting buildup of phenylalanine causing brain damage, mental retardation, or both.
If treatment isn't given within the first three weeks after birth, the child will suffer severe, permanent retardation.
Only a small percent of these children are affected by a disability like autism or mental retardation.
Congress reported that in cases where African-American children are a minority, a higher percentage of African-American children are identified with mental retardation and emotional disturbance than white students.
CDD also carries a higher chance of mental retardation than regressive autism and the loss of skills is more dramatic.
Mental retardation is not a factor in Asperger syndrome, with affected individuals ranging from average to well above average in IQ.
Individuals with high functioning autism or Asperger syndrome usually are of average or above average intelligence, whereas other forms of autism can include mental retardation.
Approximately 80 percent of males with the disorder are affected by mental retardation, most in the mild to moderate range.
Cognitive effects in females with Fragile X tend to be less severe, with only about one third having an IQ score that indicates mental retardation.
Men with a history of mental retardation in their family may be more likely to display the gene.
At this point, the Fragile X Foundation along with other medical professionals believes that any child who shows signs of autism or retardation should be tested genetically for Fragile X Syndrome.
Estimates in the percentage of people with autism meet the criteria for mental retardation range from 25 to 70 percent; while others show little or no problems with cognitive functioning.
PDDs are distinct from mental retardation in that the deficits are primarily in the realm of social skills and communication.
Just as drinking alcohol during pregnancy can result in mental retardation and physical delays, other substances may result in changes to the amygdala and temporal lobe.
The actual number of sets of apparatus it was possible to work multiplex depended upon the length of the line, for if the latter were long, retardation effects modified the working conditions.
After a very short interval of time, the length of which depends on the inductive retardation of the cable, the condensers corresponding to C 1 and C3 at the other end begin to be charged from the cable, and since the charge of C3 passes through the receiving instrument I or G the signal is recorded.
The only element of uncertainty was caused by the retardation of the current, which between Potsdam and Teheran (3000 m.) took 0 8.20 to travel; but it is probable that the final value can be accepted as correct to within os 05.
This retardation was still more pronounced in the case of tungsten-steel, which lost its magnetism at 910° and remained nonmagnetic till it was cooled to 570°, a difference of 240°.
when the secondary wave of least retardation is unobstructed, or when a ray passes through the point under consideration.
The extreme discrepancy is that between the waves which travel through the outermost parts of the object-glass at L and L'; so that if we adopt the above standard of resolution, the question is where must P be situated in order that the relative retardation of the rays PL and PL' may on their arrival at B amount to a wave-length (X).
The directions of the lateral spectra are such that the passage from one element of the grating to the corresponding point of the next implies a retardation of an integral number of wave-lengths.
These directions, in which the retardation between A and B is exactly mnX, may be called the principal directions.
On either side of any one of them the illumination is distributed according to the same law as for the central image (m = o), vanishing, for example, when the retardation amounts to (mn t 1)X.
In an engraved glass grating there is no opaque material present by which light could be absorbed, and the effect depends upon a difference of retardation in passing the alternate parts.
For if the alternate parts were equal and alike transparent, but so constituted as to give a relative retardation of :IX, it is evident that the central image would be entirely extinguished, while the first spectrum would be four times as bright as if the alternate parts were opaque.
If it were possible to introduce at every part of the aperture of the grating an arbitrary retardation, all the light might be concentrated in any desired spectrum.
6), and the diffracted rays make an angle ¢ (upon the same side), the relative retardation from each element of width (a+d) to the next is (a+d) (sin 9 +sin op); and this is the quantity which is to be equated to mX.
Then the relative retardation of the extreme rays (corresponding to the edges A, B of the grating) is mnX.
If BQ be the direction for the first minimum (the darkness between the central and first lateral band), the relative retardation of the extreme rays is (mn+1)X.
The same thing occurs if the retardation be too great.
It is easy to see that the length of the chord (which passes in all cases through 0) increases to a maximum near the place where the phase-retardation is s of a period, then diminishes to a minimum when the retardation is about a of a period, and so on.
After a rough estimate of the perturbations it must sustain from the attraction of the planets, he predicted its return for 1757,-a bold prediction at that time, but justified by the event, for the comet again made its appearance as was expected, though it did not pass through its perihelion till the month of March 1759, the attraction of Jupiter and Saturn having caused, as was computed by Clairault previously to its return, a retardation of 618 days.
Energy of Acceleration and Work of Retardation for a Shifting Body.Let w be the weight of a body which has a motion of translation in any path, and in the course of the interval of time ~t let its velocity be increased at a uniform rate of acceleration from v1 to v2.
In order to produce a retardation from the greater velocity~ v2 to the less velocity Vf, it is necessary to apply to the body a resistance connected with the retardation and the time by an equation identical in every respect with equation (71), except by the substitution of a resistance for an effort; and in overcoming that resistance the body performs work to an amount determined by equation (72), putting Rds for Pas..
Energy Stored and Restored by Deviations of Velocity.Thus a body alternately accelerated and retarded, so as to be brought back to its original speed, performs work during its retardation exactly equal in amount to the energy exerted upon it during its acceleration; so that that energy may be considered as stored during the acceleration, and restored during the retardation, in a manner analogous to the operation of a reciprocating force (~ 108).
Bertin has shown that a useful picture of the form of these curves may be obtained by taking sections, parallel to the plate, of a surface that he calls the "isochromatic surface," and that is the locus of points on the crystal at which the relative retardation of two plane waves passing simultaneously through a given point and travelling in the same direction has an assigned value.
(Reference should be made to the article Crystallography for illustrations, and for applications of these phenomena to the determination of crystal form.) With an uniaxal plate perpendicular to the optic axis, the curves of constant retardation are concentric circles and the lines of like polarization are the radii: thus with polarizer and analyser regulated for extinction, the pattern consists of a series of bright and dark circles interrupted by a black cross with its arms parallel to the planes of polarization and analysation.
In the case of a biaxal plate perpendicular to the bisector of the acute angle between the optic axes, the curves of constant retardation are approximately Cassini's ovals, and the lines of like polarization are equilateral hyperbolae passing through the points corresponding to the optic axes.
When white light is employed coloured rings are obtained, provided the relative retardation of the interfering streams be not too great.
The isochromatic lines, unless the dispersion be excessive, follow in the main the course of the curves of constant retardation, and the principal lines of like polarization are with a crossed polarizer and analyser dark brushes, that in certain cases are fringed with colour.
According to Fresnel's explanation the light in each of the interfering streams consists of two trains of waves that are circularly polarized in opposite direction and have a relative retardation of phase, introduced by the passage through the quartz: the central fringes are then due to the similarly polarized waves; the lateral systems are produced by the oppositely polarized streams, these on analysation being capable of interfering.
It consists of a parallelopiped glass so constructed that light falling normally on one end emerges at the other after two internal reflections at such an angle as to introduce a relative retardation of phase of 4r/4 between the components polarized in the principal azimuths.
Wernicke and others have established that in general light polarized in any but the principal azimuths becomes elliptically polarized by reflection, the relative retardation of phase of the components polarized in these azimuths becoming 42 at a certain angle of incidence, called the principal incidence.
One method consists in finding directly the elliptic constants of the vibration by means of a quarterwave plate and an analyser; but the more usual plan is to measure the relative retardation of two rectangular components of the stream by a Babinet's compensator.
It is clear that direct transmission through the plate at a point where the thicknesses of the prisms are d 1 and d 2 will introduce a relative retardation of (µ,; -, u o) (d l - d2) between streams polarized in planes parallel and perpendicular to the edges of the prisms,, u o, and being the ordinary and the extraordinary refractive indices; and it is hence possible by an adjustment of the thickness to reduce elliptically polarized to plane polarization at an assigned point marked off by two parallel lines.
All the rays through a given point in the first principal focal plane of the anterior system of lenses traverse the plate as a parallel beam and reunite at the corresponding point of the second focal plane of the posterior system, each in its passage being divided into two by the plate having a given relative retardation.
He shows that, supposing the cloud of particles to move around the sun in nearly circular orbits immediately outside the earth, the perturbations by the earth in the motion of the particles will result in their retardation in that part of the orbit nearest the earth, and therefore in their always being more numerous in a given space in this part of the orbit Ethan in any other.
Stokes, and which were published in the Proceedings of the Royal Society for 1855, that he discussed the mathematical theory of signalling through submarine cables, and enunciated the conclusion that in long cables the retardation due to capacity must render the speed of signalling inversely proportional to the square of the cable's length.
For the alteration of wave-length entails, at the two limits of a diffracted wave-front, a relative retardation equal to mndX.
This expresses the retardation of the extreme relatively to the central ray, and is to be reckoned positive, whatever may be the signs of w, and 0 .
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