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- All Subjects: development
- Creators: Barnes, M. Elizabeth
This study suggests an alternative way to understand and analyze community development work. Building on fieldwork in the Kumaoni Himalaya of India, it is argued that community workers make sense of the world in large part through the co-construction of dialectic identity metaphors (DIMs). These DIMs help explain to the workers the way the world works, the way it does not work, and what to do about it. More than formal community development theory, I suggest community workers look to dominant DIMs to structure organizational vision and program creation. Furthermore, ideological fragments within local DIMs contribute to the reproduction of dominant ways of knowing and the creation of best practices. For this reason, in situ examination of DIM creation and maintenance is useful for understanding how and why CWs collectively construct their identities and the co-constitutive work.
Neurocristopathies are a class of pathologies in vertebrates,
including humans, that result from abnormal expression, migration,
differentiation, or death of neural crest cells (NCCs) during embryonic development. NCCs are cells
derived from the embryonic cellular structure called the neural crest.
Abnormal NCCs can cause a neurocristopathy by chemically affecting the
development of the non-NCC tissues around them. They can also affect the
development of NCC tissues, causing defective migration or
proliferation of the NCCs. There are many neurocristopathies
that affect many different types of systems. Some neurocristopathies
result in albinism (piebaldism) and cleft palate in humans. Various
pigment, skin, thyroid, and hearing disorders, craniofacial and heart
abnormalities, malfunctions of the digestive tract, and tumors can be
classified as neurocristopathies. This classification ties a variety of
disorders to one embryonic origin.
Early in the process of development, vertebrate embryos develop a fold on the neural plate where the neural and epidermal ectoderms meet, called the neural crest. The neural crest produces neural crest cells (NCCs), which become multiple different cell types and contribute to tissues and organs as an embryo develops. A few of the organs and tissues include peripheral and enteric (gastrointestinal) neurons and glia, pigment cells, cartilage and bone of the cranium and face, and smooth muscle. The diversity of NCCs that the neural crest produces has led researchers to propose the neural crest as a fourth germ layer, or one of the primary cellular structures in early embryos from which all adult tissues and organs arise. Furthermore, evolutionary biologists study the neural crest because it is a novel shared evolutionary character (synapomorphy) of all vertebrates.
The Law of Acceleration of Growth is a theory proposed by Edward Drinker Cope in the US during the nineteenth century. Cope developed it in an attempt to explain the evolution of genera by appealing to changes in the developmental timelines of organisms. Cope proposed this law as an additional theory to natural selection. He argued that the evolution of genera, the more general groups within which biologists group species, occurs when the individual in a species move through developmental stages faster than did their ancestors, but within the same fixed period of gestation, and thus can undergo new developmental stages and develop new traits. The Law of Acceleration compliments Cope's Law of Retardation of Growth. He described the later law as the process by which organisms revert to an ancestral stage. In these cases, forces suppress the most recent traits or stages common to the development of individuals from different species within the same genus. Cope described evolution as progressive, following a predetermined path, a perspective about evolution sometimes called orthogenetic. Cope's was one among many orthogenic theories in the second half of the nineteenth century. Furthermore, the theory was part of a trend in nineteenth century in which some biologists claimed that the changes in developmental timing of organisms could explain large changes in biological forms throughout natural history.