Phosphorus fractionation in soil and sediments along a continuum from agricultural fields to nearshore lake sediments: Potential ecological impacts

The movement of phosphorus (P) from agricultural fields to streams and deposition in the nearshore of the lake presents a continuum of related physical and chemical properties that act to partition P into different physico-chemical fractions. We investigated changes in soil and sediment P fractionation as material was eroded from predominantly agricultural fields, transported via stream sediments, and deposited in a nearshore lake environment. Total phosphorus content of the soils and sediment decreased from field soils with an average concentration of 553.81 mg P kg^? 1 to 202.28 mg P kg^? 1 in stream sediments to 67.47 mg P kg^? 1 in lake sediments. Significant changes in P fractionation occurred during erosion, transport, and deposition of the particulate or sediment phase. The fractionation of P within the soils and sediments changed significantly from aluminum and organic matter associated P dominant in field soils to calcium associated P dominant in nearshore lake sediments. Various physical and chemical processes appear to be responsible for these transformations which impact the mobility and bioavailability of P. A significant amount of P was lost from field soils as they were transported and deposited. This P has either become available to biota or deposited in deeper portions of the lake system. Ultimately, the impact of P export on the nearshore lake environment may be influenced by the changes in P fractionation that occurred during transport and deposition and by the influence of macrophytes on the biogeochemical cycling of P in the sediment.     

Homodyne detection in magnetic resonance imaging

Magnetic detection of complex images in magnetic resonance imaging (MRI) is immune to the effects of incidental phase variations, although in some applications information is lost or images are degraded. It is suggested that synchronous detection or demodulation can be used in MRI systems in place of magnitude detection to provide complete suppression of undesired quadrature components, to preserve polarity and phase information, and to eliminate the biases and reduction in signal-to-noise ratio (SNR) and contrast in low SNR images. The incidental phase variations in an image are removed through the use of a homodyne demodulation reference, which is derived from the image or the object itself. Synchronous homodyne detection has been applied to the detection of low SNR images, the reconstruction of partial k-space images, the simultaneous detection of water and lipid signals in quadrature, and the preservation of polarity in inversion-recovery images.     

Gravity flow test comparisons for mildly thick consistency

Simple measurement tools that provide objective information about the consistency of thickened liquids have received increasing attention given possible application to clinical practice for dysphagia. The International Dysphagia Diet Standardization Initiative (IDDSI) advocates the use of the IDDSI Flow Test for measuring thickness and verifying a prescribed level of consistency. This study compares gravity flow test measurements taken with two 10-ml syringes of starch and gum-thickened samples prepared to a mildly thick consistency using product label information. One of the 10-ml syringes met IDDSI specification and the other 10-ml syringe did not. Thickened samples also were measured using the line spread apparatus. The results showed that two syringes yielded significantly different gravity flow test measurements, often resulting in changes to the classification level of thickness. There was no effect of thickening agent. Line spread measurements did not vary from one another. Study findings indicate the importance of continued testing with the IDDSI Flow Test and education/awareness about the use of the IDDSI reference syringe. An essential aspect about the use of thickened liquids in dysphagia management is that beverage preparations represent their prescribed level of modification. The findings of this study indicate the importance of following syringe specifications when conducting gravity flow testing using the IDDSI methodology. The implication is that the wrong 10-ml syringe could result in errant clinical decisions in determining the accuracy of texture modifications, resulting in care providers who are more likely to over or under thicken modifications to achieve a targeted level of thickness.     

Data driven search organization for continuous speech recognition

The authors describe an architecture and search organization for continuous speech recognition. The recognition module is part of the Siemens-Philips-Ipo project on continuous speech recognition and understanding (SPICOS) system for the understanding of database queries spoken in natural language. The goal of this project is a man-machine dialogue system that is able to understand fluently spoken German sentences and thus to provide voice access to a database. The recognition strategy is based on Bayes decision rule and attempts to find the best interpretation of the input speech data in terms of knowledge sources such as a language model, pronunciation lexicon, and inventory of subword units. The implementation of the search has been tested on a continuous speech database comprising up to 4000 words for each of several speakers. The efficiency and robustness of the search organization have been checked and evaluated along many dimensions, such as different speakers, phoneme models, and language models     

Multishot rosette trajectories for spectrally selective MR imaging

In nuclear magnetic resonance, different spectral components often correspond to different chemical species and as such, spectral selectivity can be a valuable tool for diagnostic imaging. In the work presented here, a multishot image acquisition method based upon rosette k-space trajectories has been developed and implemented for spectrally selective magnetic resonance imaging (MRI). Parametric forms for the gradient waveforms and design constraints are derived, and an example multishot gradient design is presented. The spectral behaviour for this imaging method is analyzed in a simulation model. For frequencies that are near to the resonant frequency, this method results in a lower intensity, but undistorted image, while for frequencies that are off-resonance by a large amount, the object is incoherently dephased into noise. A method by which acquisitions are delayed by small amounts is introduced to further reduce the residual intensity for off-resonant signals. An image reconstruction method based on convolution gridding, including a correction method for small amounts of magnetic field inhomogeneity, is implemented. Finally, the spectral selectivity is demonstrated in vivo in a study in which both water and lipid images are generated from a single imaging data set     

A low cost multichip packaging technology for monolithic microwaveintegrated circuits

This paper describes a multichip module technology based on highly impermeable liquid crystal polymers (LCPs) to interconnect and package monolithic microwave integrated circuits (MMICs). Because of the low moisture permeability of the LCPs, the packages can be made hermetic without heavy expensive housings can be two to four times lighter and one-fifth the cost of conventional ceramic based transmit/receive (T/R) modules. The LCP material has a low dielectric constant (2.65) and low-loss tangent and is manufacturable using high volume, large-area processing methods that provide very reliable high-performance circuits at low cost. Using flip-chip bonded MMICs attached to a high thermal conductivity, low coefficient of thermal expansion substrate, this innovative technology can meet a variety of commercial, military, and NASA requirements     

Videotex: Anatomy of a failure

Considerable excitement has been generated in Europe and North America in videotex - namely, the concept of electronic access in the home to centrally - located computerized databases containing vast amounts of data. However, the public offering of such services has thus far been unsuccessful in achieving significant penetrations in the residential market.Videotex is examined in this paper to illuminate possible reasons for its failure thus far in the residential marketplace. Comparisons are made with somewhat similar on-line systems for accessing computerized data-bases and for performing transactions and transmitting messages to other people. The final conclusion is that most consumers simply do not have a need nor a desire to access vast computerized data-bases of general information. Videotex or any other similar system that attempts to satisfy consumer needs for information in such a fashion will surely fail.     

Detection of ozone on Saturn's satellites Rhea and Dione

The satellites Rhea and Dione orbit within the magnetosphere of Saturn, where they are exposed to particle irradiation from trapped ions. A similar situation applies to the galilean moons Europa, Ganymede and Callisto, which reside within Jupiter's radiation belts. All of these satellites have surfaces rich in water ice. Laboratory studies of the interaction of charged-particle radiation with water ice predicted the tenuous oxygen atmospheres recently found on Europa and Ganymede. However, theoretical investigations did not anticipate the trapping of significantly larger quantities of O2 within the surface ice. The accumulation of detectable abundances of O3, produced by the action of ultraviolet or charged-particle radiation on O2, was also not predicted before being observed on Ganymede. Here we report the identification of O3 in spectra of the saturnian satellites Rhea and Dione. The presence of trapped O3 is thus no longer unique to Ganymede, suggesting that special circumstances may not be required for its production.     

Localizing the lexicon for reading aloud:replication of a PET study using fMRI

Functional magnetic resonance imaging (fMRI) was used to investigate the neural basis of written word recognition in two normal subjects. With a 1.5T scanner and temporal surface coil, T2 gradient echo images were obtained while subjects read words aloud. As a control condition, subjects visualized false font strings and said the word "range' each time such a string appeared. These two conditions were presented in an oscillatory pattern, alternating 30 s of each condition for a total of 4 min. Comparison of the two conditions using cross-correlation demonstrated strong activation in both subjects in the left posterior superior temporal gyrus, near the site predicted for the visual input lexicon by Déjerine and recently demonstrated by positron emission tomography.