Human reproductive ecology to aid infant survival and growth. Lactational strategies vary cross-culturally, but can typically be defined by sibling sets and sex ratios, frequency of nursing, entire lactational duration, and milk composition. Milk is composed of my bioconstituents, but only a few will be outlined here. In the first days of puerperium, the first milk is thick and yellowish, also called colostrum. For weeks after that, mature milk is expressed and it has been shown that fetal-mammary gland signaling occurs even before birth in determining milk type and concentrations based on the fetus sex. Colostrum plays an important role in establishing the
Quadratic form in this case the quadratic form is called positive definite (all 1) or negative definite (all −1). If none of the terms are 0, then the form is called ; this includes positive definite, negative definite, and indefinite (a mix of 1 and −1); equivalently, a nondegenerate quadratic form is one whose associated symmetric form is a nondegenerate "bilinear" form. A real vector space with an indefinite nondegenerate quadratic form of index (denoting "p" 1s and "q" −1s) is often denoted as R particularly in the physical theory of spacetime. The discriminant of a quadratic form, concretely the class of