Combination of electromagnetic induction and gamma spectrometry using K‐means clustering: A study for evaluation of site partitioning

Today rapid survey methods of proximal soil sensing (PSS) provide an increasing number of different and highly resolved data. These multidimensional data sets can lead to multilayered and complex maps of parameters which are only indirectly related to soil properties and soil functions. However, in applications usually just one clear elementary map is required. It is of increasing importance to tackle this problem utilizing a cluster algorithm for the synthesis and reduction of multidimensional input variables. The cluster algorithm provides a partitioning of the investigated site whereby the units are characterized by the statistics of the PSS data. Therefore, the question that arises is how suitable is the suggested partitioning in terms of the delineation of different soil units. In this study, we investigate the suitability of cluster partitioning through a case study at a medium‐scale test site (≈ 50 000 m²). Two common PSS methods: electromagnetic induction (EMI) and gamma spectrometry (GS) will be employed to create a data set for partitioning by a K‐means cluster. The result of the cluster analysis is a delineation of three different parts. In contrast to previous studies, we evaluate the generated partitions by independent soil properties such as grain size, horizon thickness, and color of stratified randomly taken soil samples. The soil analyses show that one of three clusters significantly differs from the others in terms of grain‐size distribution and horizon thickness. The partitioning of the other two clusters could not be confirmed by the considered soil parameters. Nevertheless, the case study demonstrates the combination of different PSS data by K‐means clustering as a potential approach for site partitioning. An evaluation of the results of the cluster analysis through the collection and analysis of soil samples is highly recommended.     

Degradation of scrapie associated prion protein (PrPSc) by the gastrointestinal microbiota of cattle

A food-borne origin of the transmission of bovine spongiform encephalopathy (BSE) to cattle is commonly assumed. However, the fate of infectious prion protein during polygastric digestion remains unclear. It is unknown at present, whether infectious prion proteins, considered to be very stable, are degraded or inactivated by microbial processes in the gastrointestinal tract of cattle. In this study, rumen and colon contents from healthy cattle, taken immediately after slaughter, were used to assess the ability of these microbial consortia to degrade PrP(Sc). Therefore, the consortia were incubated with brain homogenates of scrapie (strain 263K) infected hamsters under physiological anaerobic conditions at 37 degrees C. Within 20 h, PrP(Sc) was digested both with ruminal and colonic microbiota up to immunochemically undetectable levels. Especially polymyxin resistant (mainly gram-positive) bacteria expressed PrP(Sc) degrading activity. These data demonstrate the ability of bovine gastrointestinal microbiota to degrade PrP(Sc) during digestion.     

Cloudy apple juice is more effective than apple polyphenols and an apple juice derived cloud fraction in a rat model of colon carcinogenesis

As recently shown, a cloudy apple juice (CloA) was effective to modulate colon cancer associated parameters in rats treated with 1,2-dimethylhydrazine (DMH). To identify the bioactive substance classes in CloA, we fractionated CloA to yield a total polyphenol (PF) and a cloud (CF) fraction consisting of proteins, fatty acids, polyphenols, and cell wall polysaccharides. Rats received water (control (Cont)) or CloA, PF, and CF separate or combined (PF-CF) ad libitum for 7 weeks starting one week before the first DMH-injection. As determined by comet assay, the DMH-induced genotoxicity in colonocytes of controls (Cont/DMH: 7.7 +/- 0.5%) was significantly reduced by CloA (3.3 +/- 0.3%) but not by any of the fractions. The crypt cell proliferation induced by DMH (Cont/NaCl: 7.5 +/- 0.6%; Cont/DMH: 14.9 +/- 0.8%) was significantly decreased by CloA (9.4 +/- 0.4%), PF (12.4 +/- 0.7%), CF (11.6 +/- 0.4%), and PF-CF (12.4 +/- 0.6%). Although not statistically significant, CloA tended to reduce the number of large aberrant crypt foci (ACF) (Cont/DMH: 19.0 +/- 3.7; CloA/DMH: 12.3 +/- 1.9), while none of the fractions affected ACFs. Neither CloA nor the fractions changed mRNAs of colonic cyclooxygenases (COX-1, COX-2), glutathione-associated enzymes (GST-M2, gamma-GCS, GST-P), the splenocyte CD4/CD8 ratio, natural killer cell activity, and plasma antioxidant status. These results demonstrate that CloA had a higher cancer-preventive potential than the fractions and further, besides PF, identified CF as an additional bioactive fraction of CloA.     

Effect of region on the uncertainty in crop variety trial programs with a reduced number of trials

Results from crop variety trials may vary between geographical regions because of differences in climate and soil types. Results are usually presented at regional level. To evaluate the importance of the regions used in the Swedish variety trial programs, we examined which regions produced similar levels of yield and similar ratios in yield between cultivars; the amount by which variance could be reduced by division into regions or clusters of regions; and the amount of trials per region and year, replicates per trial, and trials per year required in order to fulfill specifications on the precision of results. Yield data from spring barley and winter wheat trials performed during 1997–2006 were studied using cluster analysis and variance component estimation. The objectives were (1) to discuss the effects of regions on precision when the number of trials has decreased; (2) to demonstrate the method; and (3) to report the results obtained. In spring barley, clusters of regions produced different levels of yield, but similar yield ratios between cultivars. In winter wheat, clusters of regions giving different yield ratios were identified. When the option of a single analysis was compared with that of region-wise analysis, the reduction in variance with the former, due to the larger number of trials, outweighed the reduction in variance with the latter due to decreased random interaction between trials and cultivars.     

Plant,Microbial and Soil Factors,Determining Nitrogen Fixation in the Rhizosphere

A genotype effect on associative (rhizosphere) N₂-fixation was observed with two cultivars of Sorghum bicolor (nutans) with a maximum rate of 8 μmol C₂H₄ · h^?1 · plant^?1 in one genotype compared to 0.9 μmol in the other. Characteristics of the high fixing genotype were a reduced transpiration rate, a lower number of stomata and increased root exudate production per gram root dry weight with higher concentration of dicarboxylic acids. The bacterial rhizosphere composition revealed a three times higher number of N₂-fixing bacteria, a tenfold reduction of actinomycetes and a threefold reduction of Arthrobacter associated with the high fixing cultivar compared to the low fixing genotype. From these and other plant rhizospheres two new nitrogen fixing bacteria, Pseudomonas stutzeri and Erwinia herbicola, were characterized. With the N₂-fixing bacteria Azospirillum brasilense and Klebsiella pneumoniae an enhancement of specific nitrogenase activity by aromatic compounds, for example phenolics, the herbicide alachlor and the insecticide carbofuran was demonstrated. An oscillating nitrogenase activity in Azospirillum brasilense under microaerobic conditions was found, resulting from an encystation and deencystation under those conditions. Experiments with wheat roots demonstrated that reduced oxygen tensions, essential for a maximum rhizosphere N₂-fixation, reduced root growth significantly and altered the N-metabolism of the roots.     

Direct observation of continuous electric dipole rotation in flux-closure domains in ferroelectric Pb(Zr,Ti)O₃

Low-dimensional ferroelectric structures are a promising basis for the next generation of ultrahigh-density nonvolatile memory devices. Depolarization fields, created by incompletely compensated charges at the surfaces and interfaces, depress the polarization of such structures. Theory suggests that under conditions of uncompensated surface charges, local dipoles can organize in flux-closure structures in thin films and vortex structures in nano-sized ferroelectrics, reducing depolarization fields. However, the continuous rotation of the dipoles required in vortex structures and the behavior of unit cell dipoles in flux-closure structures have never been experimentally established. By aberration-corrected transmission electron microscopy, we obtained experimental evidence for continuous rotation of the dipoles closing the flux of 180° domains in a ferroelectric perovskite thin film.     

The endocast of MH1, Australopithecus sediba

The virtual endocast of MH1 (Australopithecus sediba), obtained from high-quality synchrotron scanning, reveals generally australopith-like convolutional patterns on the frontal lobes but also some foreshadowing of features of the human frontal lobes, such as posterior repositioning of the olfactory bulbs. Principal component analysis of orbitofrontal dimensions on australopith endocasts (MH1, Sts 5, and Sts 60) indicates that among these, MH1 orbitofrontal shape and organization align most closely with human endocasts. These results are consistent with gradual neural reorganization of the orbitofrontal region in the transition from Australopithecus to Homo, but given the small volume of the MH1 endocast, they are not consistent with gradual brain enlargement before the transition.