Neutral-density filterIn photography and optics, a neutral-density filter, or ND filter, is a filter that reduces or modifies the intensity of all wavelengths, or colors, of light equally, giving no changes in hue of color rendition. It can be a colorless (clear) or grey filter, and is denoted by Wratten number 96. The purpose of a standard photographic neutral-density filter is to reduce the amount of light entering the lens. Doing so allows the photographer to select combinations of aperture, exposure time and sensor sensitivity that would otherwise produce overexposed pictures.
Axiom of pairingIn axiomatic set theory and the branches of logic, mathematics, and computer science that use it, the axiom of pairing is one of the axioms of Zermelo–Fraenkel set theory. It was introduced by as a special case of his axiom of elementary sets. In the formal language of the Zermelo–Fraenkel axioms, the axiom reads: In words: Given any object A and any object B, there is a set C such that, given any object D, D is a member of C if and only if D is equal to A or D is equal to B.
Seed savingIn agriculture and gardening, seed saving (sometimes known as brown bagging) is the practice of saving seeds or other reproductive material (e.g. tubers) from vegetables, grain, herbs, and flowers for use from year to year for annuals and nuts, tree fruits, and berries for perennials and trees. This is the traditional way farms and gardens were maintained for the last 12,000 years (see first agricultural revolution). In recent decades, beginning in the latter part of the 20th century, there has been a major shift to purchasing seed annually from commercial seed suppliers.
Seed libraryA seed library is an institution that lends or shares seed. It is distinguished from a seedbank in that the main purpose is not to store or hold germplasm or seeds against possible destruction, but to disseminate them to the public which preserves the shared plant varieties through propagation and further sharing of seed. The first contemporary seed library was created in 1999 at the Berkeley Ecology Center. It was called the Bay Area Seed Interchange Library (BASIL).
Heirloom plantAn heirloom plant, heirloom variety, heritage fruit (Australia and New Zealand), or heirloom vegetable (especially in Ireland and the UK) is an old cultivar of a plant used for food that is grown and maintained by gardeners and farmers, particularly in isolated or ethnic minority communities of the Western world. These were commonly grown during earlier periods in human history, but are not used in modern large-scale agriculture. In some parts of the world, it is illegal to sell seeds of cultivars that are not listed as approved for sale.
CarobThe carob (ˈkɛrəb ; Ceratonia siliqua) is a flowering evergreen tree or shrub in the Caesalpinioideae sub-family of the legume family, Fabaceae. It is widely cultivated for its edible fruit pods, and as an ornamental tree in gardens and landscapes. The carob tree is native to the Mediterranean region and the Middle East. Portugal is the largest producer of carob, followed by Italy and Morocco. In the Mediterranean Basin, extended to the southern Atlantic coast of Portugal (i.e.
