Physics is the the study of matter and its spatial motion; while it embraces the levels of nucleii, elementary particles and atoms, its domain relative to molecules and their interactions is more properly termed chemistry. The motion of particles is governed by the basic laws of physics including Newtonian mechanics (for large objects); electromagnetism; thermodynamics and quantum mechanics (in the case of molecular and smaller entities). The earliest forms of physics addressed are motions of celestial objects, and presently this field can be viewed as astrophysics. Physics also embraces the notions of the Theory of Relativity, so that the duality of space and time is addressed. Chemistry has taken on added importance in the last half century as the bridge between fundamental laws of nature and the understanding of cellular processes and replication of DNA, the basic molecule of organism genetic coding.
Aluminum is a silver-white metal, very low density (less than three times as dense as water), yet relatively strong. In addition, aluminum is ductile; that is, it can be drawn...
CalciumLast Updated on 2013-10-24 16:29:12Calcium is the chemical element with atomic number 20; it has an atomic mass of 40.078 atomic mass units (amu). The chemical symbol for calcium is Ca. Calcium is a soft gray alkaline earth metal, and is the fifth most abundant element by mass in the Earth's crust; moreover, it is the fifth most abundant dissolved ion in seawater both in terms of number of atoms and mass, after sodium, chloride, magnesium, and sulfate.
Calcium an is essential nutrient for almost all living organisms, with vital roles in cellular metabolism, especially with regard to movement of the calcium ion Ca++ into and out of the cytoplasm functions as a signal for many cellular processes. As a chief component needed in mineralization of bones and shells, calcium is the most abundant metal by mass in a large number of faunal species, especially vertebrates, testudines and mollusca.
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Complex SystemsLast Updated on 2013-10-24 15:13:11
As Science has begun to ask where the enduring features of nature come from and how they work, the answer seems to be “complex systems”. Every kind of thing and event seems to require them. As the science has advanced, and as the modern problems of economies and environmental conflicts emerge, a new kind of science is emerging that requires being very openly exploratory, using all the tools and combining all the related perspectives of others, to develop complex knowledge systems matching the variety of the complex system problems they respond to.
Systems are storms or “like storms” in many respects, complex distributed phenomena that may be either unexpectedly eventful or highly predictable. There’s still a rather wide range of opinion within science as to what complex systems are, even whether they are made of information or... More »
AERMOD Last Updated on 2013-10-05 15:00:30AERMOD is the latest generation air dispersion model designed for short-range (up to 50 kilometers) dispersion of air pollutant emissions from stationary industrial sources. It is a steady-state plume model incorporating dispersion based on planetary boundary layer (PBL) turbulence structure and scaling, and it accomodates surface and elevated emission sources as well as simple or complex terrain.
As of December 9, 2005, the U.S. EPA designated AERMOD as the preferred model to be used for compliance with any federal and state air pollution dispersion modeling requirements. As of November 9, 2006, AERMOD completely replaces the previous preferred model known as the Industrial Source Complex (ISC) model.
The AERMOD system integrates three modules:
A steady-state Gaussian dispersion model designed for short-range dispersion of continuous emissions from stationary... More »
General GlossaryLast Updated on 2013-10-02 09:39:36This general glossary compiles definitions of specialized terms used throughout the Encyclopedia of Earth. Each term listed below has had a blue link created to allow authors to link to the given term in any article without having the reader leave the page. The terms below are words or phrases for which an entire article on the Encylopedia of Earth is not necessarily envisioned:
Allohexaploidcells holding six copies of each chromosome: Cells holding six copies of each chromosome
AnuranAn amphibian that has limbs but no tail (includes all frogs and toads): An amphibian that has limbs but no tail (includes all frogs and toads)
ArheicRegion which generates no significant surface water runoff: Region that generates no significant surface water runoff
Atomic numberThe number of protons in the nucleus of a given atom: The number of protons in the nucleus of a given... More »
Public Health Statement for DDT, DDE, and DDDLast Updated on 2013-10-01 23:28:36This article is a verbatim version of the original and is not available for edits or additions by EoE editors or authors. Companion articles on the same topic that are editable may exist within the EoE.
CAS#: DDT 50-29-3, DDE 72-55-9, DDD 72-54-8
This Public Health Statement is the summary chapter from the Toxicological Profile for DDT, DDE, and DDD. It is one in a series of Public Health Statements about hazardous substances and their health effects. A shorter version, the ToxFAQs™, is also available. This information is important because this substance may harm you. The effects of exposure to any hazardous substance depend on the dose, the duration, how you are exposed, personal traits and habits, and whether other chemicals are present. For more information, call the ATSDR Information Center at 1-888-422-8737.
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