Studies in the structure and metamorphic petrology of the Eo-Cambrian rocks of Eastern Seiland, North Norway

The rocks exposed on the eastern part of the island of Seiland are the metasedimentary envelope to the large basic and ultrabasic plutons that make up the western part of the island and the neighbouring island of Stjernoy. These metasediments have been intensely deformed and metamorphosed, thus all sedimentary structures have been obliterated. The metasedimentary sequence is, therefore, a structural one. The lowest group is the psammitic Komagnes Group. This is followed by the Eidvageid Schist Group which is followed by the relatively thin psammitic Trollvann Group. Structurally above this is the pelitic Olderbugten Group and finally the dominantly psammitic Olderfjord Group. Broadly speaking two major fold-forming deformations have been recognised; F.1 and F.2. The latter part of the first phase, which was responsible for tight isoclinal folds and a penetrative schistosity, was accompanied by intrusion of sheets of basic material parallel to the axial planes of the early folds. During the static interval separating the two deformations the maximum grade of metamorphism was achieved, this, however, varies across the area and a sequence of metamorphic isograds have been recognised. The highest grade occurs in the west and is marked by a kyanite-sillimanite porphyroblastesis, migmatisation and intrusion of adamellitic sheets. The lowest grade in the east is characterised by albite, biotite, epidote, hornblende assemblages in the psammites of the Lower Komagnes Group. These isograds reflect a contemporaneous lateral change in metamorphic grade. Following the development of these high grade assemblages in the west, there was a phase of intense flattening leading to the development of mylonitic textures in the rocks. It is suggested that this deformation phase is related to a rising basic asthenolith. The majority of folds on the area are attributed to F.2.By the onset of F.2. the metamorphic grade appears to have waned to sub-garnet grade conditions. The folds have a very variable style. In the east, they have intensely attenuated long-limbs with a number of vertically-stacked folds in the short-limbs. In the west, the limbs are of more equal length. This change in style is related to the different states of competence of the rocks at the onset of F.2. A ubiquitous feature of F.2. folds on both the major and minor scale, is the curvature of their axial-lines. In the east a number of oblique boudins have been recorded which post-date F.2. They are closely associated with rotated tension-gashes and monoclinal folds. It is suggested that all these structures were formed in response to a progressive deformation sequence. This sequence was also responsible for the development of the late Caledonian thrusts on the mainland. In the north of the area there is a pronounced swing in strike. A number of open folds are associated with this swing. These folds have been designated F.3. Monoclinal warps have been recorded in the east of the area. Their temporal relationship to the F.3. folds in the north is not known. The final phase of movement in the area led to the development of joints, faults and locally kink-folds. The prevailing metamorphic grade during this phase of deformation, and indeed all the phases subsequent to F.2., was the Quartz-Albite-Muscovite-Chlorite Sub-facies of the Greenschist Facies.<p

HHpXRF study of recent zinc and lead pollution on lava stepping stones from Pompeii: Tourist footfall, tyre dust and leaded petrol

A helium‐enabled Niton X‐ray analyser (HHpXRF) study of 296 lava stepping stones from ancient Pompeii showed that their surfaces were contaminated with superficial deposits of Zn and Pb. Recent research has shown that concentrations of these elements are highest in urban areas, where they were attributed to tyre dust and leaded petrol, respectively. The distribution of these elements on the stepping stones is represented on maps of the site. Zn pollution is most abundant in areas visited by tourists and is attributed mostly to wear from their rubber‐soled footwear. Pb pollution is attributed to the movement of onsite vehicles using leaded petrol

Longitudinal Analysis of Group A Streptococcus emm Types and emm Clusters in a High-Prevalence Setting: Relationship between Past and Future Infections.

Group A Streptococcus is a pathogen of global importance, but despite the ubiquity of group A Streptococcus infections, the relationship between infection, colonization, and immunity is still not completely understood. The M protein, encoded by the emm gene, is a major virulence factor and vaccine candidate and forms the basis of a number of classification systems. Longitudinal patterns of emm types collected from 457 Fijian schoolchildren over a 10-month period were analyzed. No evidence of tissue tropism was observed, and there was no apparent selective pressure or constraint of emm types. Patterns of emm type acquisition suggest limited, if any, modification of future infection based on infection history. Where impetigo is the dominant mode of transmission, circulating emm types either may not be constrained by ecological niches or population immunity to the M protein, or they may require several infections over a longer period of time to induce such immunity.info:eu-repo/semantics/publishe

Structural basis for the enantiospecificities of R- and S-specific phenoxypropionate/α-ketoglutarate dioxygenases

(R)- and (S)-dichlorprop/α-ketoglutarate dioxygenases (RdpA and SdpA) catalyze the oxidative cleavage of 2-(2,4-dichlorophenoxy)propanoic acid (dichlorprop) and 2-(4-chloro-2-methyl-phenoxy)propanoic acid (mecoprop) to form pyruvate plus the corresponding phenol concurrent with the conversion of α-ketoglutarate (αKG) to succinate plus CO2. RdpA and SdpA are strictly enantiospecific, converting only the (R) or the (S) enantiomer, respectively. Homology models were generated for both enzymes on the basis of the structure of the related enzyme TauD (PDB code 1OS7). Docking was used to predict the orientation of the appropriate mecoprop enantiomer in each protein, and the predictions were tested by characterizing the activities of site-directed variants of the enzymes. Mutant proteins that changed at residues predicted to interact with (R)- or (S)-mecoprop exhibited significantly reduced activity, often accompanied by increased Km values, consistent with roles for these residues in substrate binding. Four of the designed SdpA variants were (slightly) active with (R)-mecoprop. The results of the kinetic investigations are consistent with the identification of key interactions in the structural models and demonstrate that enantiospecificity is coordinated by the interactions of a number of residues in RdpA and SdpA. Most significantly, residues Phe171 in RdpA and Glu69 in SdpA apparently act by hindering the binding of the wrong enantiomer more than the correct one, as judged by the observed decreases in Km when these side chains are replaced by Ala