Determining the specific characteristics of a cell nucleus presented as karyogram (a diagrammatic representation a complete chromosome set). The material for karyotyping can be obtained from almost any tissue including amniotic fluid, blood, bone marrow, and tissue from the placenta. With such material, a test can be performed to identify any structural changes in chromosomes. …
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Kana scripts
Japanese scripts in which the characters represent ‘moras‘ that are mostly consonant-vowel syllables; the Japanese use two syllabaries called ‘hiragana‘ and ‘katakana‘. There is a higher incidence of illiteracy among Japanese children when reading kanji (a script borrowed from Chinese) compared to kana. The differences between the two scripts go beyond the fact that one …
Kangaroo-care
Also known as the kangaroo mother method, it originated in Bogotá, Columbia as a cost-effective means of caring for the very preterm or low-birthweight infant during the period of neonatal intensive care. The method, which has spread to neonatal intensive care units in Europe and North America, involves periods of skin-to-skin contact between infant and …
Justice
A balancing of claims in disputes or in distribution of resources. Founded on concepts derived from equity, ethics, law, natural law and religion, it amounts to a theory of moral rightness. One of the foremost spokespersons for this point-of-view was John Rawls (1921-2002) who wrote in his book A theory of justice (1999) that “Justice …
Joint capsule
Connective tissue surrounding a synovial joint and containing synovial fluid (see figure below for further details). A typical joint capsule. Hyaline cartilage is a semi-transparent cartilage with a blue tint, consisting of cells that synthesize a surrounding matrix of hyaluronic acid (a viscous mucopolysaccharide), collagen (a fibrous protein that makes up tough connective tissues such …
Joule
An SI unit defined as the energy required equivalent to the work done when the point of application of a force of one newton moves a distance of one meter in the direction of the force. A formally defined conversion factor is that 4.1868 joules = one calorie. The term joule was devised by the …
Joint attention
The awareness that self and a partner are both attending to the same object or event. Descriptively, it is the sharing of attention to a common object by two people interacting with each other, such as a mother and her child (see figure below). On this basis, infants begin to engage in sustained bouts of …
Iterative cycle of construction
Aniteration is, literally, a repetition of a particular operation or process thatbuilds upon the results of the preceding operation or process. An iteration canalso be viewed as a cycle, in that it takes some sort of starting point,performs an operation on that starting point to obtain a particular result,which is then used as the starting …
Jacob-Monod operon model
An influential model of prokaryotic gene expression by François Jacob and Jacques Monod (1910-1976) first published in 1960, and in which the distinctions were made between structural, operator and regulator genes. The operator genes determine when protein synthesis in the adjacent structural genes will occur and achieve this by interacting with the cell environment by …
Isotonic contraction
Generation of muscle shortening without an increase in tension. Thus, muscle length changes, but tension remains unchanged, with the resultant movement of a body part. Such a voluntary contraction of skeletal muscle, can only happen when the maximal force of contraction generated by a muscle is greater than the external force acting on the muscle. …