(via m-artyr)
HYDRAULIC FRACTURING or FRACKING is the technique used to release natural gases (shale, tight, coal seam), petroleum or other substances.
A distinction can be made between low-volume hydraulic fracturing used to stimulate high-permeability reservoirs, which may consume typically 20,000 to 80,000 US gallons (76,000 to 300,000 l; 17,000 to 67,000 imp gal) of fluid per well, with high-volume hydraulic fracturing, used in the completion of tight gas and shale gas wells; high-volume hydraulic fracturing can use as much as 2 to 3 million US gallons (7.6 to 11 Ml) of fluid per well.This latter practice has come under scrutiny internationally, with some countries suspending or even banning it. The first use of hydraulic fracturing was in 1947, though the current fracking technique was first used in the late 1990s in the Barnett Shale in Texas.
Detractors point to potential environmental impacts, including contamination of ground water, risks to air quality, the migration of gases and hydraulic fracturing chemicals to the surface, surface contamination from spills and flowback and the health effects of these. State and federal regulatory agencies and the industry are working to address these concerns. The EPA is conducting a study, set to be released for peer review at the end of 2012, of hydraulic fracturing’s impact on drinking water and ground water resources.
Click here to sign the petition to ban fracking in California.
Even if there is only one possible unified theory, it is just a set of rules and equations. What is it that breathes fire into the equations and makes a universe for them to describe?
Stephen Hawking (via expose-the-light)
"Bye bye unemployment benefits" ›
More than 200,000 long-term jobless Americans will lose their unemployment checks this week, when eight states roll off the federal extended benefits program.
Nearly half of them live in California, and the rest reside in Florida, Illinois, North Carolina, Colorado, Connecticut, Pennsylvania and Texas.
The federal extended benefits program has provided the jobless with up to 20 weeks of unemployment checks after they’ve run through their state and their federal emergency benefits, which together last up to 79 weeks.
But the extended benefits program is expiring throughout the country as the economy improves. To be eligible for these benefits, a state must show that its unemployment rate is at least 10% higher than it was in at least one of the past three years.
State unemployment rates have been falling as the jobless find new positions or exit the workforce. For instance, Nevada has the highest state unemployment rate at 12%, but it’s still below the 14% it logged in October 2010.
Sun’s Twin Discovered — the Perfect SETI Target?
There are 10 billion stars in the Milky Way galaxy that are the same size as our sun. Therefore it should come as no surprise that astronomers have identified a clone to our sun lying only 200 light-years away.
Still, it is fascinating to imagine a yellow dwarf that is exactly the same mass, temperature and chemical composition as our nearest star. In a recent paper reporting on observations of the star — called HP 56948 — astronomer Jorge Melendez of the University of San Paulo, Brazil, calls it “the best solar twin known to date.”
A triangulated irregular network (TIN) is one of different digital data structures used in geographic information systems (GIS) for the representation of a surface. TINs are arranged in a network of nonoverlapping triangles.
An advantage of using a TIN over a raster DEM in mapping and analysis is that the points of a TIN are distributed variably based on an algorithm that determines which points are most necessary to an accurate representation of the terrain. Hence, it’s an efficient representation since it requires few triangles in flat areas. It’s also good at capturing significant slope features like ridges. TINs were first invented by Callum Hale.
The Blog..: Physician Pay and Happiness ›
Physician income overall has declined since 2010, yet there are tiny glimmers of hope in some specialties. Frustration is mounting, however, and doctors in every specialty are bracing for what they expect to be further income declines as healthcare elements are implemented, such as accountable…
![contemplatingmadness:
Thomae’s function, named after Carl Johannes Thomae, also known as the popcorn function, the raindrop function, the countable cloud function, the modified Dirichlet function, the ruler function,[1] the Riemann function or the Stars over Babylon (by John Horton Conway) is a modification of the Dirichlet function. This real-valued function f(x) is defined as follows:
If x = 0 we take q = 1. It is assumed here that gcd(p, q) = 1 and q > 0 so that the function is well-defined and non-negative.
Discontinuities
The popcorn function is perhaps the simplest example of a function with a complicated set of discontinuities: f is continuous at all irrational numbers and discontinuous at all rational numbers.
Informal Proof
Clearly, f is discontinuous at all rational numbers: since the irrationals are dense in the reals, for any rational x, no matter what ε we select, there is an irrational a even nearer to our x where f(a) = 0 (while f(x) is positive). In other words, f can never get “close” and “stay close” to any positive number because its domain is dense with zeroes.
To show continuity at the irrationals, assume without loss of generality that our ε is rational (for any irrational ε, we can choose a smaller rational ε and the proof is transitive). Since ε is rational, it can be expressed in lowest terms as a/b. We want to show that f(x) is continuous when x is irrational.
Note that f takes a maximum value of 1 at each whole integer, so we may limit our examination to the space between and . Since ε has a finite denominator of b, the only values for which f may return a value greater than ε are those with a reduced denominator no larger than b. There exist only a finite number of values between two integers with denominator no larger than b, so these can be exhaustively listed. Setting δ to be smaller than the nearest distance from x to one of these values guarantees every value within δ of x has f(x) < ε.](http://24.media.tumblr.com/tumblr_m32lonrc6E1qcyo2po1_500.png)
Thomae’s function, named after Carl Johannes Thomae, also known as the popcorn function, the raindrop function, the countable cloud function, the modified Dirichlet function, the ruler function,[1] the Riemann function or the Stars over Babylon (by John Horton Conway) is a modification of the Dirichlet function. This real-valued function f(x) is defined as follows:
If x = 0 we take q = 1. It is assumed here that gcd(p, q) = 1 and q > 0 so that the function is well-defined and non-negative.
Discontinuities
The popcorn function is perhaps the simplest example of a function with a complicated set of discontinuities: f is continuous at all irrational numbers and discontinuous at all rational numbers.
Informal Proof
Clearly, f is discontinuous at all rational numbers: since the irrationals are dense in the reals, for any rational x, no matter what ε we select, there is an irrational a even nearer to our x where f(a) = 0 (while f(x) is positive). In other words, f can never get “close” and “stay close” to any positive number because its domain is dense with zeroes.
To show continuity at the irrationals, assume without loss of generality that our ε is rational (for any irrational ε, we can choose a smaller rational ε and the proof is transitive). Since ε is rational, it can be expressed in lowest terms as a/b. We want to show that f(x) is continuous when x is irrational.
Note that f takes a maximum value of 1 at each whole integer, so we may limit our examination to the space between
and
. Since ε has a finite denominator of b, the only values for which f may return a value greater than ε are those with a reduced denominator no larger than b. There exist only a finite number of values between two integers with denominator no larger than b, so these can be exhaustively listed. Setting δ to be smaller than the nearest distance from x to one of these values guarantees every value within δ of x has f(x) < ε.
