15,903 research outputs found
New approaches to the measurement of chlorophyll, related pigments and productivity in the sea
In the 1984 SBIR Call for Proposals, NASA solicited new methods to measure primary production and chlorophyll in the ocean. Biospherical Instruments Inc. responded to this call with a proposal first to study a variety of approaches to this problem. A second phase of research was then funded to pursue instrumentation to measure the sunlight stimulated naturally occurring fluorescence of chlorophyll in marine phytoplankton. The monitoring of global productivity, global fisheries resources, application of above surface-to-underwater optical communications systems, submarine detection applications, correlation, and calibration of remote sensing systems are but some of the reasons for developing inexpensive sensors to measure chlorophyll and productivity. Normally, productivity measurements are manpower and cost intensive and, with the exception of a very few expensive multiship research experiments, provide no contemporaneous data. We feel that the patented, simple sensors that we have designed will provide a cost effective method for large scale, synoptic, optical measurements in the ocean. This document is the final project report for a NASA sponsored SBIR Phase 2 effort to develop new methods for the measurements of primary production in the ocean. This project has been successfully completed, a U.S. patent was issued covering the methodology and sensors, and the first production run of instrumentation developed under this contract has sold out and been delivered
Shuttle GPS R/PA evaluation analysis and performance tradeoff study
Primary responsibility was understanding and analyzing the various GPS receiver functions as they relate to the shuttle environment. These receiver functions included acquisition properties of the sequential detector, acquisition and tracking properties of the various receiver phase locked loops, and the techniques of sequential receiver operation. In addition to these areas, support was provided in the areas of oscillator stability requirements, antenna management, and navigation filter requirements, including preposition aiding
Synthesis of hetero-bifunctional, end-capped oligo-EDOT derivatives
Conjugated oligomers of 3,4-ethylenedioxythiophene (EDOT) are attractive materials for tissue engineering applications, and as model systems for studying the properties of the widely used polymer PEDOT. We report here the facile synthesis of a series of keto-acid end-capped oligo-EDOT derivatives (n = 2-7) through a combination of a glyoxylation end capping strategy and iterative direct arylation chain extension. Importantly, these structures not only represent the longest oligo-EDOTs reported, but are also bench stable in contrast to previous reports on such oligomers. The constructs reported here can undergo subsequent derivatization for integration into higher order architectures, such as those required for tissue engineering applications. The synthesis of hetero-bifunctional constructs, as well as those containing mixed monomer units is also reported, allowing further complexity to be installed in a controlled manner. Finally, we describe the optical and electrochemical properties of these oligomers and demonstrate the importance of the keto-acid in determining their characteristics
Properties of the mechanosensitive channel MscS pore revealed by tryptophan scanning mutagenesis
Funding This work was supported by a Wellcome Trust Programme grant [092552/A/10/Z awarded to I.R.B., S.M., J. H. Naismith (University of St Andrews, St Andrews, U.K.), and S. J. Conway (University of Oxford, Oxford, U.K.)] (T.R. and M.D.E.), by a BBSRC grant (A.R.) [BB/H017917/1 awarded to I.R.B., J. H. Naismith, and O. Schiemann (University of St Andrews)], by a Leverhulme Emeritus Fellowship (EM-2012-060\2), and by a CEMI grant to I.R.B. from the California Institute of Technology. The research leading to these results has received funding from the European Union Seventh Framework Programme (FP7/2007-2013 FP7/2007-2011) under Grant PITN-GA-2011-289384 (FP7-PEOPLE-2011-ITN NICHE) (H.G.) (awarded to S.M.).Peer reviewedPublisher PD
SPS phase control system performance via analytical simulation
A solar power satellite transmission system which incorporates automatic beam forming, steering, and phase control is discussed. The phase control concept centers around the notation of an active retrodirective phased array as a means of pointing the beam to the appropriate spot on Earth. The transmitting antenna (spacetenna) directs the high power beam so that it focuses on the ground-based receiving antenna (rectenna). A combination of analysis and computerized simulation was conducted to determine the far field performance of the reference distribution system, and the beam forming and microwave power generating systems
Probing 5f-state configurations in URu2Si2 with U L3-edge resonant x-ray emission spectroscopy
Resonant x-ray emission spectroscopy (RXES) was employed at the U L3
absorption edge and the La1 emission line to explore the 5f occupancy, nf, and
the degree of 5f orbital delocalization in the hidden order compound URu2Si2.
By comparing to suitable reference materials such as UF4, UCd11, and alpha-U,
we conclude that the 5f orbital in URu2Si2 is at least partially delocalized
with nf = 2.87 +/- 0.08, and does not change with temperature down to 10 K
within the estimated error. These results place further constraints on
theoretical explanations of the hidden order, especially those requiring a
localized f2 ground state.Comment: 11 pages,7 figure
Influence of the Hydric Environment on Water Exchange and Hatchlings of Rigid-Shelled Turtle Eggs
To examine the possible influence of incubation substrate water potential on rigid-shelled chelonian eggs and hatchlings, rigid-shelled eggs from four clutches of Brisbane River turtle (Emydura signata) were incubated buried in vermiculite at water potentials of approximately -100, -350, and -850 kPa, and patterns of egg mass change and hatchling attributes were examined. All eggs hatched successfully, and there was no apparent effect of water potential on incubation period, fresh hatchling mass, hatchling water content, or hatchling size. Clutch of origin also had no apparent effect on these attributes when initial egg mass was used as a covariate. However, clutch of origin affected initial egg mass, and clutch of origin and incubation water potential influenced the amount of water exchanged between the eggs and their environment during incubation and the amount of residual yolk found in hatchlings. Substrate water potential has little effect on hatchling outcomes other than the proportion of yolk converted to hatchling tissue during incubation in the rigid-shelled eggs of E. signata. It would appear that in general, the substrate water potential during incubation affects the quality of chelonian hatchlings by influencing the amount of yolk converted to hatchling tissue during embryonic development and that this influence is stronger in flexible-shelled eggs than in rigid-shelled eggs
The effect of the annealing temperature on the local distortion of LaCaMnO thin films
Mn -edge fluorescence data are presented for thin film samples (3000~\AA)
of Colossal Magnetoresistive (CMR) LaCaMnO: as-deposited,
and post-annealed at 1000 K and 1200 K. The local distortion is analyzed in
terms of three contributions: static, phonon, and an extra,
temperature-dependent, polaron term. The polaron distortion is very small for
the as-deposited sample and increases with the annealing temperature. In
contrast, the static distortion in the samples decreases with the annealing
temperature. Although the local structure of the as-deposited sample shows very
little temperature dependence, the change in resistivity with temperature is
the largest of these three thin film samples. The as-deposited sample also has
the highest magnetoresistance (MR), which indicates some other mechanism may
also contribute to the transport properties of CMR samples. We also discuss the
relationship between local distortion and the magnetization of the sample.Comment: 11 pages of Preprint format, 8 figures in one tar fil
Haematopoietic Stem Cell Transplantation for Primary Haemophagocytic Lymphohistiocytosis
Haematopoietic stem cell transplantation currently remains the only curative treatment of primary forms of haemophagocytic lymphohistiocytosis (HLH). Rapid diagnosis, efficient primary treatment of hyperinflammation, and conditioning regimens tailored to this demanding condition have substantially improved prognosis in the past 40 years. However, refractory hyperinflammation, central nervous system (CNS) involvement, unavailability of matched donors, susceptibility to conditioning-related toxicities, and a high frequency of mixed chimaerism remain a challenge in a substantial proportion of patients. Gene therapeutic approaches for several genetic defects of primary HLH are being developed at pre-clinical and translational levels
Ytterbium divalency and lattice disorder in near-zero thermal expansion YbGaGe
While near-zero thermal expansion (NZTE) in YbGaGe is sensitive to
stoichiometry and defect concentration, the NZTE mechanism remains elusive. We
present x-ray absorption spectra that show unequivocally that Yb is nearly
divalent in YbGaGe and the valence does not change with temperature or with
nominally 1% B or 5% C impurities, ruling out a valence-fluctuation mechanism.
Moreover, substantial changes occur in the local structure around Yb with B and
C inclusion. Together with inelastic neutron scattering measurements, these
data indicate a strong tendency for the lattice to disorder, providing a
possible explanation for NZTE in YbGaGe.Comment: 4 pages, 4 figure, supplementary inf
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