Two-dimensional hybrid element image reconstruction for TMillumination

A Newton's iterative scheme for electromagnetic imaging is proposed for reconstruction of the dielectric properties of inhomogeneous, lossy bodies with arbitrary shape. The algorithm is based on a finite element (FE) representation which is coupled to a boundary element (BE) formulation for the forward solution of the electric fields; together these are termed the hybrid element method. It utilizes FE discretization of only the area of interest while incorporating the RE method to match the conditions of the homogeneous background region extending to infinity. This paper presents image reconstruction for the 2D TM polarization case where two classes of dielectric distributions are studied which demonstrate the flexibility of this method along with some of the difficulties associated with larger imaging problems     

Expression of inducible nitric oxide synthase in human burn wounds

A water-soluble synthetic peptide with only nine amino acid residues, comprising the 131-139 sequence region of the cytotoxic protein alpha-sarcin (secreted by the mold Aspergillus giganteus), interacts with large unilamellar vesicles composed of acid phospholipids. It promotes lipid mixing between bilayers and leakage of vesicle aqueous contents, and it also abolishes the phospholipid phase transition. Other larger peptides containing such an amino acid sequence also produce these effects. These peptides acquire alpha-helical conformation in the presence of trifluoroethanol, but display beta-strand conformation in the presence of sodium dodecyl sulfate. The interaction of these peptides with the lipid vesicles also results in beta-structure. The obtained data are discussed in terms of the involvement of the 131-139 stretch of alpha-sarcin in its interaction with lipid membranes.     

A comparison of category and letter fluency in Alzheimer's disease and Huntington's disease.

44 patients with dementia of the Alzheimer type (DAT), 44 elderly normal control (ENC) Ss demographically matched to the DAT group, 42 patients with Huntington's disease (HD), and 42 middle-aged normal control (MNC) Ss demographically matched to the HD group were administered letter and category fluency tasks. DAT patients showed an overproportional impairment on category than on letter fluency tasks, whereas HD patients were equally impaired. Analyses based on receiver operating characteristic curves revealed that category fluency correctly classified significantly more DAT and ENC Ss than did letter fluency, whereas the 2 fluency tasks did not differ in this respect for HD and MNC Ss. Results suggest that HD patients' failures on fluency tasks are caused by impaired initiation/retrieval capacities. In contrast, DAT patients' greater category than letter fluency deficits are primarily due to a breakdown in the structure of semantic knowledge. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Measurement of ultralow gate tunneling currents using floating-gate integrator technique

We report for the first time that a gate tunneling current measurement sensitivity better than 3/spl times/10/sup -22/ A has been achieved by using a floating-gate integrator technique. The technique involves monitoring the charge change in the floating-gate integrated with an on-chip op-amp and an on-chip feedback capacitor. We used this technique to study the stress-induced leakage current (SILC) and its cycling dependence of 70 /spl Aring/ oxides in the direct tunneling region at oxide voltage as low as 1.9 V. The technique has been validated through correlation to direct measurement on MOSFET arrays and theoretical calculations. The measured SILC current is modeled with an Inelastic trap-assisted tunneling model.     

The P9 pocket of HLA-DQ2 (non-Aspbeta57) has no particular preference for negatively charged anchor residues found in other type 1 diabetes-predisposing non-Aspbeta57 MHC class II molecules

Susceptibility and resistance to type 1 diabetes are associated with MHC class II alleles that carry non-Asp and Asp at residue 57 of their beta chain respectively. The effect of Asp or non-Aspbeta57 may relate to a differential ability of distinct class II molecules to bind specific immuno-pathogenic peptides. Recent studies in man and mouse have revealed that some type 1 diabetes-predisposing non-Aspbeta57 class II molecules (i.e. DQ8, DR4Dw15 and I-Ag7) preferentially bind peptides with a negatively charged anchor residue at P9. It has been suggested that this is a common feature of type 1 diabetes-predisposing class II molecules. The molecular explanation for such a phenomenon could be that class II beta chains with Aspbeta57 form a salt bridge between Aspbeta57 and a conserved Arg of the a chain, whereas in non-Aspbeta57 molecules the Arg is unopposed and free to interact with negatively charged P9 peptide anchor residues. We have investigated the specificity of the P9 pocket of the type 1 diabetes-associated DQ2 molecule and in particular examined for charge effects at this anchor position. Different approaches were undertaken. We analyzed binding of a high-affinity binding ligand and P9-substituted variants of this peptide, and we analyzed the binding of a set of synthetic random peptide libraries. The binding analyses were performed with wild-type DQ2 and a mutated DQ2 with Ala at beta57 substituted with Asp. Our results indicate that the wild-type DQ2 (non-Aspbeta57) prefers large hydrophobic residues at P9 and that there is no particular preference for binding peptides with negatively charged residues at this position. The specificity of the P9 pocket in the mutated DQ molecule is altered, indicating that the beta57 residue contributes to determining the specificity of the P9 pocket. Our data do not lend support to the hypothesis that all non-Asp beta57 class II molecules predispose to development of disease by binding peptides with negatively charged P9 anchor residues.     

Absolute Isotopic Abundance Ratios and Atomic Weight of a Reference Sample of Nickel

Absolute values have been obtained for the isotopic abundance ratios of a reference sample of nickel (Standard Reference Material 986), using thermal ionization mass spectrometry. Samples of known isotopic composition, prepared from nearly isotopically pure separated nickel isotopes, were used to calibrate the mass spectrometers. The resulting absolute isotopic ratios are: ⁵⁸Ni/⁶⁰Ni=2.596061±0.000728, ⁶¹Ni/⁶⁰Ni=0.043469±0.000015,⁶²Ni/⁶⁰Ni=0.138600±0.000045, and ⁶⁴Ni/⁶⁰Ni=0.035295±0.000024, which yield atom percents of ⁵⁸Ni=68.076886 ±0.005919, ⁶⁰Ni = 26.223146±0.005144,⁶¹Ni=1.139894±0.000433, ⁶²Ni =3.634528±0.001142, and ⁶⁴Ni =0.925546±0.000599. The atomic weight calculated from this isotopic composition is 58.693353 ±0.000147. The indicated uncertainties are overall limits of error based on two standard deviations of the mean and allowances for the effects of known sources of possible systematic error.     

Magnetic-resonance-imaging-coupled broadband near-infrared tomography system for small animal brain studies

A novel magnetic-resonance-coupled broadband near-infrared (NIR) tomography system for small animal brain studies is described. Several features of the image formation approach are new in NIR tomography and represent major advances in the path to recovering high-resolution hemoglobin and oxygen saturation images of tissue. The NIR data were broadband and continuous wave and were used along with a second-derivative-based estimation of the path length from water absorption. The path length estimation from water was then used along with the attenuation spectrum to recover absorption and reduced scattering coefficient images at multiple wavelengths and then to recover images of total hemoglobin and oxygen saturation. Going beyond these basics of NIR tomography, software has been developed to allow inclusion of structures derived from MR imaging (MRI) for the external and internal tissue boundaries, thereby improving the accuracy and spatial resolution of the properties in each tissue type. The system has been validated in both tissue-simulating phantoms, with 10% accuracy observed, and in a rat cranium imaging experiment. The latter experiment used variation in inspired oxygen (FiO2) to vary the observed hemoglobin and oxygen saturation images. Quantitative agreement was observed between the changes in deoxyhemoglobin values derived from NIR and the changes predicted with blood-oxygen-level-dependent (BOLD) MRI. This system represents the initial stage in what will likely be a larger role for NIR tomography, coupled to MRI, and illustrates that the technological challenges of using continuous-wave broadband data and inclusion of a priori structural information can be met with careful phantom studies.