984 resultados para Albedo at given wavelength
Resumo:
This report describes an efficient strategy for determining the functions of sequenced genes in microorganisms. A large population of cells is subjected to insertional mutagenesis. The mutagenized population is then divided into representative samples, each of which is subjected to a different selection. DNA is prepared from each sample population after the selection. The polymerase chain reaction is then used to determine retrospectively whether insertions into a particular sequence affected the outcome of any selection. The method is efficient because the insertional mutagenesis and each selection need only to be performed once to enable the functions of thousands of genes to be investigated, rather than once for each gene. We tested this "genetic footprinting" strategy using the model organism Saccharomyces cerevisiae.
Resumo:
NADPH diaphorase (NADPH dehydrogenase; EC 1.6.99.1) histochemistry labels neurons that synthesize the neurotransmitter nitric oxide (NO). In retina, it has been demonstrated that NO can affect the metabolism of cGMP in rod photoreceptors. To investigate potential involvement of NO in cone photoreceptor activity, we utilized NADPH diaphorase histochemistry to study the cone-dominated retina of the tree shrew (Tupaia belangeri). Unexpectedly, our results revealed different NADPH diaphorase activity in the cellular subcompartments of the spectral classes of cone photoreceptors. Although all cones showed intense labeling of inner segment ellipsoids, the short-wavelength-sensitive (SWS or "blue-sensitive") cones and the rods displayed intense staining of the myoid inner segment subcompartment as well. Furthermore, only SWS cones and rods displayed surface labeling of their nuclei. These findings indicate a manner in which SWS cones differ biochemically from other cone types and in which they are more similar to rods. Such differences may underlie some of the unusual functional properties of the SWS cone system, which have been attributed to postreceptoral processes.
Resumo:
The practical application of optical antennas in detection devices strongly depends on its ability to produce an acceptable signal-to-noise ratio for the given task. It is known that, due to the intrinsic problems arising from its sub-wavelength dimensions, optical antennas produce very small signals. The quality of these signals depends on the involved transduction mechanism. The contribution of different types of noise should be adapted to the transducer and to the signal extraction regime. Once noise is evaluated and measured, the specific detectivity, D*, becomes the parameter of interest when comparing the performance of antenna coupled devices with other detectors. However, this parameter involves some magnitudes that can be defined in several ways for optical antennas. In this contribution we are interested in the evaluation and comparison of D_ values for several bolometric optical antennas working in the infrared and involving two materials. At the same time, some material and geometrical parameters involved in the definition of noise and detectivity will be discussed to analyze the suitability of D_ to properly account for the performance of optical antennas.
Resumo:
Lists books donated by a Dr. Chauncy, Mr. Pemberton, Joseph Green, William W. Kitwell(?), Mr. Sec[retar]y Oliver, William Greenleaf, Moses Gill, Mr. Bradstreet, Dr. Isaac Foster, Brigadier General Royall, Nicholas Sever, M.(?) Condy, Mr. Dolbear, Rev. Mr. Harris, Mr. Browne, Stephen Greenleaf, Thomas Cushing, Mr. Orne, Mr. Agar, Mr. Marion, Mr. Fleet, Mr. Davies, Mr. Barrett, Dr. Grant, and possibly others. Entries include author, title, volume number, and occasionally format.
Resumo:
This small notebook with marbled paper covers contains three Latin addresses delivered by Adam Winthrop during Harvard College ceremonies: the valedictory oration on Class Day, 1724, the "Oratio Salutatoria" at the 1724 Commencement, and the "Oratio Gratulatoria" which closed the exercises of the 1727 Commencement. The last page of the volume is signed "Adam Winthrop Jun'r."
Resumo:
One-page inventory of the silver, including the weight of each object, donor, and dates; one passage is crossed out, and written diagonal to the inventory are the words "Fort London Farmer London." Docketed on the verso with an address to the Right Honorable Samuel Bishop of York.