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
Invariant of a binary form 4"c""a" − "a""d" of degree 4. The algebra of covariants is generated by the discriminant, the form itself (degree 1, order 3), the Hessian "H" (degree 2, order 2) and a covariant "T" of degree 3 and order 3. They are related by the syzygy 4"H"="Df"-"T" of degree 6 and order 6. The algebra of invariants of a quartic form is generated by invariants "i", "j" of degrees 2, 3. This ring is naturally isomorphic to the ring of modular forms of level 1, with the two generators corresponding to the Eisenstein series "E" and "E". The algebra of covariants