Geostatistical assessment and validation of uncertainty for three-dimensional dioxin data from sediments in an estuarine river

Contaminated sediment management is an urgent environmental and regulatory issue worldwide. Because remediation is expensive, sound quantitative assessments of uncertainty aboutthe spatial distribution of contaminants are critical, butthey are hampered bythe physical complexity of sediment environments. This paper describes the use of geostatistical modeling approaches to quantify uncertainty of 2,3,7,8-tetrachlorodibenzo-p-dioxin concentrations in Passaic River (New Jersey) sediments and to incorporate this information in decision-making processes, such as delineation of contaminated areas and additional sampling needs. First, coordinate transformation and analysis of three-dimensional semivariograms were used to describe and modelthe directional variability accounting forthe meandering course of the river. Then, indicator kriging was employed to provide models of local uncertainty at unsampled locations without requiring a prior transform (e.g. log-normal) of concentrations. Cross-validation results show that the use of probability thresholds leads to more efficient delineation of contaminated areas than a classification based on the exceedence of regulatory thresholds by concentration estimates. Depending on whether additional sampling aims at reducing prediction errors or misclassification rates, the variance of local probability distributions or a measure of the expected closeness to the regulatory threshold can be used to locate candidate locations.     

Prognostic value of bcl-2 expression in patients with operable carcinoma of the uterine cervix

The nucleus retroambiguus (NRA) is a group of premotor neurons at the transition between brainstem and spinal cord. It projects to certain motoneuronal cell groups, among which is a distinct set of motoneurons in the lumbar enlargement innervating muscles including iliopsoas, adductor longus, and hamstrings. To find out whether these NRA-motoneuronal projections are monosynaptic, injections of wheat germ-agglutinin horseradish peroxidase (WGA-HRP) into the NRA were combined with injections of cholera toxin subunit b (CTb) into the hamstring muscles. Electron microscopical examination revealed that the NRA terminal profiles make monosynaptic contacts with dendrites of motoneurons innervating these muscles. The NRA terminal profiles formed asymmetrical synapses, and contained spherical and a few dense core vesicles. These findings provide evidence of monosynaptic NRA-hindlimb motoneuronal projections which are likely to be excitatory.     

Extra-cellular volume estimation by electrical impedance--phase measurement or curve fitting: a comparative study

The intestinal polyamine transporters have not yet been identified. Our aim was to characterize specific polyamine binding sites in rabbit intestinal brush-border membranes (IBBM) as a starting step for identification of polyamine transporters. This was investigated at 4 degrees and at low membrane concentration. Saturation isotherms for [3H]putrescine (PUT) binding indicated a single population of sites (puT) with a dissociation equilibrium constant Kd of 3.8 microM and a density of sites Bmax of 58 pmol/mg of protein. [3H]spermidine (SPD) binding also involved only one class of sites (spD), albeit with a lower affinity (Kd = 106 microM) and higher abundance (Bmax = 1240 pmol/mg of protein) than puT. On the contrary, [14C]spermine (SPM) bound two classes of sites (spM1 and spM2) differing in their affinity (Kd = 2.5 and 31.4 microM) and abundance (Bmax = 467 and 1617 pmol/mg of protein, respectively). Membrane association of SPM at 4 degrees was much faster than that of SPD and PUT, both of which proceeded at a similar rate. In contrast to PUT and SPD dissociation, SPM dissociation at 23 degrees did not follow a first-order reaction. Specifically bound [3H]PUT, unlike [3H]SPD and [14C]SPM, dissociated at 23 degrees independently of the addition of nonradioactive polyamine. Methylglyoxal-bis-(guanylhydrazone) was an extremely potent inhibitor of PUT binding (Ki = 3.2 +/- 1.5 nM), but as with PUT and cadaverine (CAD), it did not alter [3H]SPD and [14C]SPM binding substantially. The intestinal brush-border membrane may contain at least three sites specific for polyamine binding and exhibiting different ligand selectivity. Site puT might be associated with the transport system already described for intestinal uptake of PUT.     

Vibrational properties of nitrogen-doped ultrananocrystalline diamond films grown by microwave plasma CVD

Ultrananocrystalline diamond (UNCD) films grown in an argon-rich Ar/CH₄/H₂ microwave plasma with nitrogen gas added in amounts of 0%–20% were studied by Raman spectroscopy with multiple excitation wavelengths in the range of 244–647 nm and by optical absorption in UV–visible. The Raman spectra have demonstrated the presence of diamond, amorphous carbon and polyacetylene in the UNCD films. Analysis of vibrational and optical properties of amorphous carbon phase proves that nitrogen stimulates the transition from amorphous carbon into an ordered graphite-like structure with narrowed optical band gap, which is supposed to be responsible for the high electrical conductivity of the N-doped UNCD.