13,482 research outputs found
Noncariogenic Sweeteners: Sugar Substitutes for Caries Control
The evidence is clear that the incidence of dental caries is related to the frequency of eating sugar. The use of sugar substitutes is a suggested way of reducing sugar intake. A variety of noncariogenic sweeteners exists, but most have no practical value for caries control because of their technical or safety problems, taste, or cost. Urinary bladder tumorigenic effects have been reported in experimental animals treated with saccharin and cyclamates. Because of concerns for human safety, cyclamates were banned in the U.S., and saccharin use was permitted only by special legislation. The polyalcohols sorbitol and xylitol are important sugar substitutes since they are not efficient substrates for plaque bacteria and therefore produce only minimal plaque pH drop.
Aspartame, with its sugar-like taste, is an excellent low-calorie sweetener now used in over 100 products under the name NutraSweet. Consumption of aspartame by normal humans is safe and does not promote tooth decay. Individuals with a need to control their phenylalanine intake should handle aspartame like any other source of phenylalanine
Detection of alteration associated with a porphyry copper deposit in southern Arizona
Computer processing of Landsat MSS data was performed using contrast stretching and band-to-band ratioing. A false color ratio composite picture showed color anomalies which coincided with known areas of alteration on and about Red Mountain. A helicopter survey of the study area was undertaken using a portable field reflectance spectrometer. One hundred fifty-six spectra were obtained in the 0.4 to 2.5 micrometer wavelength region. The spectra were digitized, and contour maps for 24 wavelength intervals were produced; no spectral anomalies were evident for the known altered areas. A contour map produced from the 1.6 and 2.2 micrometer ratio generally delineated the alteration areas. The 1.3, 1.6, and 2.2 micrometer wavelength data were canonically transformed using a transformation empirically derived from discriminant function analysis of altered and unaltered materials for the Goldfield, Nevada region, and a contour map was produced for the first canonical variable. The known areas of alteration were clearly defined on the contour map
A quantum algorithm providing exponential speed increase for finding eigenvalues and eigenvectors
We describe a new polynomial time quantum algorithm that uses the quantum
fast fourier transform to find eigenvalues and eigenvectors of a Hamiltonian
operator, and that can be applied in cases (commonly found in ab initio physics
and chemistry problems) for which all known classical algorithms require
exponential time. Applications of the algorithm to specific problems are
considered, and we find that classically intractable and interesting problems
from atomic physics may be solved with between 50 and 100 quantum bits.Comment: 10 page
Mechanisms for Lasing with Cold Atoms as the Gain Medium
We realize a laser with a cloud of cold rubidium atoms as gain medium, placed
in a low-finesse cavity. Three different regimes of laser emission are observed
corresponding respectively to Mollow, Raman and Four Wave Mixing mechanisms. We
measure an output power of up to 300 W and present the main properties of
these different lasers in each regime
Spontaneous Synchrony Breaking
Research on synchronization of coupled oscillators has helped explain how
uniform behavior emerges in populations of non-uniform systems. But explaining
how uniform populations engage in sustainable non-uniform synchronization may
prove to be just as fascinating
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