Spectral atmospheric observations at Nantucket Island, May 7-14, 1981

An experiment was conducted by the National Langley Research Center to measure atmospheric optical conditions using a 10-channel solar spectral photometer system. This experiment was part of a larger series of multidisciplinary experiments performed in the area of Nantucket Shoals aimed at studying the dynamics of phytoplankton production processes. Analysis of the collected atmospheric data yield total and aerosol optical depths, transmittances, normalized sky radiance distributions, and total and sky irradiances. Results of this analysis may aid in atmospheric corrections of remote sensor data obtained by several sensors overflying the Nantucket Shoals area. Recommendations are presented concerning future experiments using the described solar photometer system and calibration and operational deficiencies uncovered during the experiment

Regulation of asymmetric neurogenesis in c. elegans

Neural specification is further complicated when we consider that it needs to be coordinated across the left-right (L/R) axis. Disruptions in the bilaterally symmetric organization of the human brain are frequently observed in patients with neurological disorders. Furthermore, certain neurological disorders such as schizophrenia and Parkinson's disease present or progress asymmetrically, suggesting the possibility of underlying asymmetric genetic causes. The question of how early neural specification is regulated to produce both bilaterally symmetric and L/R asymmetric structures has been largely unexplored

A variant of nested dissection for solving n by n grid problems

Nested dissection orderings are known to be very effective for solving the sparse positive definite linear systems which arise from n by n grid problems. In this paper nested dissection is shown to be the final step of incomplete nested dissection, an ordering which corresponds to the premature termination of dissection. Analyses of the arithmetic and storage requirements for incomplete nested dissection are given, and the ordering is shown to be competitive with nested dissection under certain conditions

Regulation of asymmetric neurogenesis in c. elegans

Neural specification is further complicated when we consider that it needs to be coordinated across the left-right (L/R) axis. Disruptions in the bilaterally symmetric organization of the human brain are frequently observed in patients with neurological disorders. Furthermore, certain neurological disorders such as schizophrenia and Parkinson's disease present or progress asymmetrically, suggesting the possibility of underlying asymmetric genetic causes. The question of how early neural specification is regulated to produce both bilaterally symmetric and L/R asymmetric structures has been largely unexplored

Reducing Polarization Mode Dispersion With Controlled Polarization Rotations

One of the fundamental limitations to high bit rate, long distance, telecommunication in optical fibers is Polarization Mode Dispersion (PMD). Here we introduce a conceptually new method to reduce PMD in optical fibers by carrying out controlled rotations of polarization at predetermined locations along the fiber. The distance between these controlled polarization rotations must be less than both the beat length and the mode coupling length of the fiber. This method can also be combined with the method in which the fiber is spun while it drawn. The incidence of imperfections on the efficiency of the method is analysed.Comment: 4 page

A W:B4C multilayer phase retarder for broadband polarization analysis of soft x-ray radiation \ud

A W:B4C multilayer phase retarder has been designed and characterized which shows a nearly constant phase retardance between 640 and 850 eV photon energies when operated near the Bragg condition. This freestanding transmission multilayer was used successfully to determine, for the first time, the full polarization vector at soft x-ray energies above 600 eV, which was not possible before due to the lack of suitable optical elements. Thus, quantitative polarimetry is now possible at the 2p edges of the magnetic substances Fe, Co, and Ni for the benefit of magnetic circular dichroism spectroscopy employing circularly polarized synchrotron radiatio

Geometric scaling of purely-elastic flow instabilities

We present a combined experimental, numerical and theoretical investigation of the geometric scaling of the onset of a purely-elastic flow instability in a serpentine channel. Good qualitative agreement is obtained between experiments, using dilute solutions of flexible polymers in microfluidic devices, and two-dimensional numerical simulations using the UCM model. The results are confirmed by a simple theoretical analysis, based on the dimensionless criterion proposed by Pakdel-McKinley for onset of a purely-elastic instability

Summary of Results of Field Experiments.

The aim of these experiments was to determine the relationship between bromegrass and ryegrass densities and their effects on wheat yields and in one case lupin yield 81 BA 45, Competition between bromegrass, ryegrass and wheat. 81 KA 28, Competition between bromegrass, ryegrass and wheat. 81 ME 35, Competition between bromegrass, ryegrass and wheat 81 TS 28, Competition between bromegrass, ryegrass and wheat. 81 WH 48, Competition between bromegrass, ryegrass and wheat. 81 NA 30, Competition between bromegrass, ryegrass and wheat. 81 MT 42, Abandoned due to severe waterlogging and disease. The wheat failed. The weeds grew magnificently. 81 MO 33, Competition between bromegrass, ryegrass and lupin

Fractional Stokes-Einstein and Debye-Stokes-Einstein relations in a network forming liquid

We study the breakdown of the Stokes-Einstein (SE) and Debye-Stokes-Einstein (DSE) relations for translational and rotational motion in a prototypical model of a network-forming liquid, the ST2 model of water. We find that the emergence of ``fractional'' SE and DSE relations at low temperature is ubiquitous in this system, with exponents that vary little over a range of distinct physical regimes. We also show that the same fractional SE relation is obeyed by both mobile and immobile dynamical heterogeneities of the liquid

Intrinsic and structural isotope effects in Fe-based superconductors

The currently available results of the isotope effect on the superconducting transition temperature T_c in Fe-based high-temperature superconductors (HTS) are highly controversial. The values of the Fe isotope effect (Fe-IE) exponent \alpha_Fe for various families of Fe-based HTS were found to be as well positive, as negative, or even be exceedingly larger than the BCS value \alpha_BCS=0.5. Here we demonstrate that the Fe isotope substitution causes small structural modifications which, in turn, affect T_c. Upon correcting the isotope effect exponent for these structural effects, an almost unique value of \alpha~0.35-0.4 is observed for at least three different families of Fe-based HTS.Comment: 4 pages, 2 figure