Flanks Of Structures Research Articles

Large-scale genomic survey and characterization of mcr genes carried by foodborne Cronobacter isolates.

Antibiotic resistance has become a worldwide public health and biosafety problem. The clinical efficacy of colistin was jeopardized by the report of the first mobile colistin resistance (mcr) gene, and subsequently, the mcr-gene family of mcr-1 to mcr-10 has been identified. Cronobacter is an emerging foodborne opportunistic pathogen, which can cause neonatal meningitis, bacteremia, and necrotizing enterocolitis (NEC) by contaminating food. However, the entire picture of foodborne Cronobacter carriage of the mcr genes is not known. Here, we investigated the mcr genes of Cronobacter isolates (N = 877) by whole-genome sequencing. We found 133 of 877 previously undescribed Cronobacter isolates carrying mcr genes. Further genomic analysis revealed that these mcr genes mainly belonged to the mcr-9 and mcr-10. Genomic analysis of the flanking structures of mcr genes revealed that two core flanking structures were prevalent in foodborne Cronobacter isolates, and the flanking structure carrying IS1R was found for the first time in this study. These findings suggest that foodborne Cronobacter isolates carrying the mcr genes already pose a threat to human health. IMPORTANCE Cronobacter is an emerging foodborne opportunistic pathogen, which can cause neonatal meningitis, bacteremia, and NEC by contaminating food. However, the entire picture of foodborne Cronobacter carriage of the mcr genes is not known. Here, we investigated the mcr genes of Cronobacter isolates by whole-genome sequencing and found 133 previously undescribed Cronobacter isolates carrying mcr genes. Further genomic analysis revealed that these mcr genes mainly belonged to the mcr-9 and mcr-10. Genomic analysis of the flanking structures of mcr genes revealed that two core flanking structures were prevalent in foodborne Cronobacter isolates, and the flanking structure carrying IS1R was found for the first time in this study.

Development of flanking structures in layered gneissic rock: Insights from numerical modelling

Flanking structures defined by dragged planar fabrics alongside of quartzo-feldspathic veins in gneissic rocks are very common. Varieties of mesoscale flanking structures were observed in parts of the Chhotonagpur Granite Gneissic Complex (CGGC), Eastern India. Alternate thin layering of quartzo-feldspathic and mafic minerals in gneissic rock causes mechanical anisotropy in rock during deformation. This study aims to explore specially the influence of mechanical anisotropy on the development of flanking structures. With the help of two –dimensional Finite Element modelling, we attempt to understand the effect of initial orientation of cross-cutting element (θ), kinematic vorticity number (Wk) and the anisotropy factor (δ) on the development of flanking structures. Deformed shape of cross-cutting element (RN), amount (LN) and nature (antithetic or synthetic) of offset of layers and pattern of drag (reverse or normal) are considered as important parameters for their nomenclature. As the final geometry of flanking structure does not only depend on the instantaneous deformational condition, we analyze the progressive development of flanking structures by varying the above parameters. Study reveals that mechanical anisotropy has strong influence on the geometry of flanking structures in layered gneissic rock, which depends on the initial orientation of long axis of cross-cutting element and its final position with respect to the orientation of principal stress axes and pole of anisotropy. The study also reveals that the flanking structures can be used as important tool for estimating the mechanical anisotropy in layered rock. Shape of cross-cutting element, amount of offset and the shifting of the object-tip points are the most important parameters for determining the anisotropy factor.

Wettable flank routable thin MicroLeadFrame for automotive applications

Driven by the higher power density and harsh environments in automotive, leadframe package has been varied to meet the higher requirement of reliability and integration. Quad Flat No-Lead (QFN) packages is known to provide the small form factor, and adequate for the high power package system. However, due to its wet pad characteristics, the solder volume is thin without fillet endangering the structural reliability. Therefore, it is very important to ensure structural integrity by constructing sound solder fillet, and it is mandatory for industry to inspect visually the soldering state after the bonding process. Wettable flank QFN is designed for this particular purpose. In this study, the routable thin MicroLeadFrame®, an wettable flank technology which allows easy process by employing chemical etching yet enables the side solder visible inspection for fine lead pitch, is introduced and explored. Process to achieve the wettable flank structure was developed, and the reliability was studied through Automotive Electronics Council (AEC) reliability test under package level and board level. Also, mechanical shear test and simulation was carries out to verify the wettable flank structure feasibility to the automotive electronics packaging by demonstrating excellent reliability performances.

Transtensional flanking structures

Flanking structures are deflections of an existing planar fabric (e.g., foliation) alongside a cross-cutting element (e.g., a vein) that can develop in a wide range of rock types and glacier ice. Nearly all published examples of flanking structures are interpreted to have formed either under simple shear or transpressional general shear, although theoretically they should also form under transtensional general shear. This paper describes the geometry and development of transtensional flanking structures in glacial ice of the Pasterze, Austria's largest alpine valley glacier. The cross-cutting elements are a few metres long and are interpreted as fractures that rotate into the shear flow and consequently accommodate anti- and synthetic offset, forming a- and s-type flanking folds. However, shear bands, with co-shearing cross-cutting elements inclined against the shear flow, are absent. The geometries of the mapped structures are successfully reproduced with a semi-analytical modified Eshelby solution for a frictionless cross-cutting element embedded in a linear viscous medium deforming under a remote transtensional sub-simple shear. The geometry of the mapped flanking folds, the absence of shear bands, the spatial variation of cross-cutting element orientations and the geometry of the glacier's splaying crevasses are consistent with two-dimensional transtensional sub-simple shear caused by down-glacier valley widening.

Gravity Forward and Inversion Modelling in Improving the Geology Model of the Flank Volcanic Structure

Cross-sections of volcanic structures are generally constructed using existing surface rock data. The detailed subsurface is not accessible because of a limited approach; as a result, precision is less accurate. Geophysical data obtained from surface gravity measurements will improve this phenomenon based on the response of density variation through forward and inverse modelling. The joint interpretation will make it possible to improve the subsurface model and to apply it in volcano deposits that experience a throw. Gravity data acquisition is 200 points over an area of 16 × 14 square kilometres. An anomaly study will focus on near-surface phenomena, where modelling shows that inversion needs to be enhanced by mesh refinement. In addition, forward modelling renders the model more realistic. The results show, the fault reaches a half km. It is not seen in the geology section, and the density variation shows 0.3 grams/cc. This density change is interpreted for the pyroclastic in the depression segment. Fumaroles may interpret as the water percolating pathway from the peak through the flank structure. The meteoric water flows inside the volcanic deposits and the fault plane is the ends of the meteoric water reaching the outside.

Cretaceous petroleum system modeling of Kairouan Basin in eastern Tunisia

Upper Cretaceous deposits in central eastern Tunisia represent a potential proven source rocks from Cenomanian–Albian Fahdene and Turonian Bahloul Formations and reservoir rocks of Turonian Bireno, Douleb, and Campanian–Maastrichtian Abiod Formations. The latter form the main oil and gas field systems in onshore and offshore central eastern Tunisia. Seismic tectonics and seismic stratigraphy based on 2D seismic analyses calibrated to the petroleum well’s wireline logging led to the identification of source rock and reservoir sequence distribution between high platforms and subsiding basin areas. This structuring has been created by inherited deep-seated transtensive and transpressive flower faults (Kairouan-Sousse, Hdadja, El Jem, Mahdia, etc.) that are intruded by Triassic halokinetic evaporites. Geochemical analyses and modeling of the well and pseudo-well deposits using BasinMod 1D software from a plate river had permitted to differentiate kitchen areas, within the basin areas, that have high maturity level (late oil to gas generation phase) of Fahdene and Bahloul Cretaceous source rocks. The neighboring high flank structures might constitute good traps to accumulate expelled materials. The large-scale fault system and the dense fracture network related to the Kairouan Basin borders represent a preferential pathway for fluids to reach updip flank reservoir units. The geochemistry modeling was performed in order to characterize the maturity, generation, and expulsion timing of hydrocarbons. In addition, this study highlights the great gas shale potential steel remaining in the subsiding basin kitchens.

Lithuanian experience of application the masonry cavity walls in multistory buildings with sound insulation requirements

Cavity walls could be used instead of homogeneous walls in order to reduce the load acting on the ceiling structure while ensuring conformity with the acoustic requirements for buildings. The airborne sound insulation properties of nonbearing cavity walls comprising two masonry leaves with a filled gap are dealt in this paper. Cavity wall structures erected from silicate brickwork, hollow silicate, gypsum, and aerated concrete block work having general surface mass from 125 to 500 kg/m2 were analyzed under in situ conditions. Standardized calculation methods for the weighted sound reduction index, Rw, assessment are compared with the in situ measurement results of apparent, R′w, index ones. Field measurements of R′w index were conducted during the mandatory pre-completion testing introduced in Lithuania since 2007 for newly erected buildings. The resonance effect that occurs due to the cavity in the studied structures and reduces R′ index values below 800 Hz appropriately lessens the single number value, R′w. By increasing the width of cavity as well as using sound-absorbing material between masonry elements, this limiting frequency may be shifted to the lower frequency band. Obtained measurements data show that standardized models intended for homogeneous walls could properly indicate the sound insulation properties of cavity walls having a relatively high (>350 kg/m2) general surface mass. For cavity walls with lower than 350 kg/m2 general surface mass values, measurement showed higher R′w values than for standardized models. The two types of cavity wall supporting are classified for evaluation of the cavity wall together with flanking structures on acting of loads: strong supported and weak supported. For the strong supported structures, increasing of the R′w index was from 3 dB to 8 dB compared with standardized models. For the weak supported structures, increasing of the R′w index was from 1 dB to 4 dB for less than 200 kg/m2 surface mass cavity walls. Appropriate calculation regression formulas were proposed to predict the value of the R′w index for cavity walls of both types.

High prevalence of blaCTX-M-14 among genetically diverse Escherichia coli recovered from retail raw chicken meat portions in Japan

Global widespread of extended-spectrum β-lactamase (ESBL)-producing Enterobacteriaceae, especially Escherichia coli poses a greater threat in healthcare and community settings of humans. Raw meats from food animals colonized with ESBL producers may be one of important transmission routes for those bacteria in the community. This study investigated the presence of ESBL-producing E. coli in retail raw chicken and pork meats in Japan. ESBL producers were detected from the 59 of 150 (39.3%) chicken samples, but none were from all the 50 pork samples tested. The blaCTX-M-14 (17; 24.3%) was most frequently identified, followed by blaCTX-M-2 (16; 22.9%), blaSHV-12 (11; 15.7%), and blaCTX-M-55 (10; 14.3%) among a total of 70 ESBL-producing E. coli isolates from 59 chicken samples. The isolates with blaCTX-M-14 were often combined with phylogroup B1 (9/17) mainly composed of ST162 (7/9), and phylogroup F (5/17) with diverse STs. The blaCTX-M-14 was basically associated with the common elements ISEcp1 and ΔIS903 or IS903 in all 17 isolates. In 6 isolates, comprising 5 phylogroup B1-ST162 and a nontypeable-ST162 isolates, an IS26-truncated ISEcp1 was identified upstream of the blaCTX-M-14, and a fosA3 was further located downstream of ΔIS903. Furthermore, some mobile genetic elements mediating blaCTX-M-14 unique to raw chicken meat portions were identified. The blaCTX-M-2 gene was preceded by ISEcp1 or ISCR1 in 16 isolates, whereas the presence of Δorf3 downstream of blaCTX-M-2 was limited only in 6 isolates from Brazilian samples though they exhibited diverse phylogroups and STs. The blaCTX-M-55 and blaCTX-M-1 shared classical flanking structures, ISEcp1-blaCTX-M-orf477, although the length of spacer sequences between ISEcp1 and the start codon of blaCTX-M was 45 bp and 80 bp for blaCTX-M-55 and blaCTX-M-1, respectively. Among blaSHV-12-harboring isolates, ST38 was frequently detected (6/11) though their phylogroup distribution varied.In conclusion, besides transmission of bla gene-harboring E. coli lineages which have adaptability to both human and chicken, spread of mobile genetic elements associated with bla genes from E. coli lineages adapted to chicken to those adapted to human is highly suggested. Our results provide important information to gain a better understanding of the transmission risk of bla genes from retail chicken meats to human.

Amino acid content of beta strands and alpha helices depends on their flanking secondary structure elements

The influence of flanking structures (alpha helices and beta strands in the primary sequence) on amino acid content of the elements of secondary structure has been analyzed in seven sets of nonhomologous proteins. Elevated usage of beta structural amino acid residues and pentapeptides in beta strands between two alpha helices can be explained by the stabilization of secondary structure of those beta strands by natural selection. High usage of alpha helical amino acids and pentapeptides in beta strands situated between two other beta strands is an evidence of the relaxation of natural selection: “passive” beta strands in these fragments of polypeptide chains are frequently formed due to the influence of flanking “active” beta strands. Alpha helices situated between alpha helix and beta strand are enriched by alpha helical pentapeptides and have lower usage of beta structural pentapeptides than those situated between beta strand and alpha helix, their N-termini are more frequently protected from helix to beta transitions by Glu residues. Alpha helices between two beta strands are stabilized by Ala residues and pentapeptides specific to alpha helices. Dipeptide content of the most stable alpha helices and beta strands was used for the creation of the PentaFOLD 2.0 algorithm (http://chemres.bsmu.by) that finds stable fragments of these elements of secondary structure in PDB files.

Inflation Leading to a Slow Slip Event and Volcanic Unrest at Mount Etna in 2016: Insights From CGPS Data

AbstractGlobal Positioning System (CGPS) data from Mount Etna between May 2015 and September 2016 show intense inflation and a concurrent Slow Slip Event (SSE) from 11 December 2015 to 17 May 2016. In May 2016, an eruptive phase started from the summit craters, temporarily stopping the ongoing inflation. The CGPS data presented here give us the opportunity to determine (1) the source of the inflating body, (2) the strain rate parameters highlighting shear strain rate accumulating along NE Rift and S Rift, (3) the magnitude of the SSE, and (4) possible interaction between modeled sources and other flank structures through stress calculations. By analytical inversion, we find an inflating source 5.5 km under the summit (4.4 km below sea level) and flank slip in a fragmented shallow structure accommodating displacements equivalent to a magnitude Mw6.1 earthquake. These large displacements reflect a complex mechanism of rotations indicated by the inversion of CGPS data for strain rate parameters. At the scale of the volcano, these processes can be considered precursors of seismic activity in the eastern flank of the volcano but concentrated mainly on the northern boundary of the mobile eastern flank along the Pernicana Fault and in the area of the Timpe Fault System.

Hanna of Wyoming—The Rockies’ Deepest Basin

The Hanna Basin is one of the world’s deeper intracratonic depressions. It contains exceptionally thick sequences of mature, hydrocarbon-rich Paleozoic through Eocene rocks and has the requisite structural and depositional history to be a significant petroleum province. The Tertiary Hanna and Ferris formations consist of up to 20,000 ft of organic-rich lacustrine shale, shaly mudstone, coal, and fluvial sandstone. The Upper Cretaceous Medicine Bow, Lewis, and Mesaverde formations consist of up to 10,000 ft of marine and nonmarine organic-rich shale enclosing multiple stacked beds of hydrocarbon-bearing sandstone. Significant shows of oil and gas in Upper Cretaceous and Paleocene rocks occur in the basin. Structural prospecting should be most fruitful around the edges where Laramide flank structures were created by out-of-the-basin thrust faults resulting from deformation of the basin’s unique 50-mile wide by 9-mile deep sediment package. Strata along the northern margin of the basin were compressed into conventional anticlinal folds by southward forces emanating from Emigrant Trail-Granite Mountains overthrusting. Oil and gas from Pennsylvanian to Upper Cretaceous aged rocks have been found in such structures near the Hanna Basin. Only seven wells have successfully probed the deeper part of the Hanna Basin (not including Anadarko’s #172 Durante lost hole, Sec. 17, T22N, R82W, lost in 2004, hopelessly stuck at 19,700 ft, unlogged and untested). Two of these wells tested gas at commercial rates from Upper Cretaceous rocks at depths of 10,000 to 12,000 ft. Sparse drilling along the Hanna Basin’s flanks has also revealed structures from 3,000 to 7,000 feet deep which yielded significant shows of oil and gas.

Meso-scale flanking structure and micro-scale push up structure within migmatitic biotite granite, Peninsular Gneissic Complex, Southern India

Meso-scale flanking structure and micro-scale push up structure within migmatitic biotite granite, Peninsular Gneissic Complex, Southern India

Sheath fold development in monoclinic shear zones

AbstractWe use numerical simulations to investigate the evolution of sheath folds around slip surfaces in simple‐shear‐dominated monoclinic shear zones. A variety of sheath fold shapes develops under general shear, including tubular folds with low aspect ratio eye patterns and tongue‐like structures showing bivergent flanking structures in sections normal to the sheath elongation, which may potentially lead to confusing shear sense interpretations. Not all investigated monoclinic flow end‐members lead to the development of sheath folds sensu stricto (folds with apical angle <90°). The aspect ratio of the eye patterns, Ryz, correlates with the ratio between the principal strain in the Y‐direction and the smaller of the principal strains in the X–Z plane, and thus it could be used in strain analysis.

Analog Models of Flanking Structures and a Natural Example in the Quadrilátero Ferrífero, Minas Gerais.

The aim of this study is to present analog models of flanking structures and to analyze the Fábrica Nova synform, Quadrilátero Ferrífero, Minas Gerais, from a geometric point of view. We set up seven models using a linear viscous silicone and produced flanking structures with a shear velocity of 2 cm h-1. At different initial orientations with respect to the shear zone boundary, a rigid cross-cutting element with lubricated boundaries was deformed via sinistral bulk flow at a shear strain of γ = 1.28. The most interesting features of our experiments are the geometries of the different marker lines, which are heterogeneous and resulted from thickening and thinning of the silicone at the cross-cutting element terminations. To compare our analog models and the Fábrica Nova synform, we analyzed the outermost marker line of the analog models and the top surface of the Cauê Formation in the Paleoproterozoic metasediments. The best comparisons between the experiments and the natural example were obtained by our CIS90 model in terms of the flexure shape near the cross-cutting element and the cross-cutting element orientation. Thus, we suggest that the cross-cutting elements in both situations act as obstacles and consequently produce local perturbations in laminar flow.

Regional Spread of CTX-M-2-Producing Proteus mirabilis with the Identical Genetic Structure in Japan.

In this study, we analyzed the molecular epidemiology of extended-spectrum β-lactamase (ESBL)-producing Proteus mirabilis isolates collected from the central region of Japan. Between 2005 and 2012, 820 clinical P. mirabilis isolates were obtained from ten acute care hospitals in Japan. We characterized ESBL confirmatory test-positive isolates by sequencing the ESBL genes and their flanking regions, detecting plasmid replicons, and performing pulsed-field gel electrophoresis (PFGE). Ninety-six isolates (12%) were positive according to the ESBL confirmatory test; all these isolates possessed blaCTX-M-2 with the same flanking structure of upstream ΔISEcp1 and a downstream region identical to downstream blaKLUA-1. IncT was the prevalent, and only, replicon found in 63 isolates. PFGE analysis detected eight clusters with more than one isolate, among which three included 56 isolates and six included isolates from multiple hospitals. CTX-M-2-producing P. mirabilis with an identical genetic structure flanking blaCTX-M-2 is dominant in this Japanese region, and there is evidence for the clonal spread of isolates.

Strain localization in ultramylonitic marbles by simultaneous activation of dislocation motion and grain boundary sliding (Syros, Greece)

Abstract. Extreme strain localization occurred in the centre of the cross-cutting element of a flanking structure in almost pure calcite marbles from Syros, Greece. At the maximum displacement of 120 cm along the cross-cutting element, evidence of grain size sensitive deformation mechanisms can be found in the ultramylonitic marbles, which are characterized by (1) an extremely small grain size ( ∼ 3 µm), (2) grain boundary triple junctions with nearly 120° angles, (3) a weak crystallographic preferred orientation with very low texture index (J = 1.4), (4) a random misorientation angle distribution curve and (5) the presence of small cavities. Using transmission electron microscopy, a deformation sequence is observed comprising recrystallization dominantly by bulging, resulting in the development of the fine-grained ultramylonite followed by the development of a high dislocation density ( ∼ 1013 m−2) with ongoing deformation of the fine-grained ultramylonite. The arrangement of dislocations in the extremely fine-grain-sized calcite differs from microstructures created by classical dislocation creep mediated by combined glide and thermally activated climb. Instead, it exhibits extensive glide and dislocation networks characteristic of recovery accommodated by cross-slip and network-assisted dislocation movement without formation of idealized subgrain walls. The enabling of grain boundary sliding to dislocation activity is deemed central to initiating and sustaining strain softening and is argued to be an important strain localization process in calcite rocks, even at a high strain rate ( ∼ 10−9 s−1) and low temperature (300 °C).

An Integrated Methodology To Locate Oil Opportunities in Mature Reservoirs

This article, written by JPT Technology Editor Chris Carpenter, contains highlights of paper IPTC 18004, “An Integrated Methodology To Locate the Remaining-Oil Opportunities in Mature Reservoirs in Offshore Sarawak, Malaysia,” by M.J. Zulhaimi, W.M.S. Wan Ibrahim, S. Sanyal, K.A. Zamri, M.N. Mohamad, and K.N.M. Zaini, EORC; R.D. Tewari, Petronas; and A.K. Pradhan, ADCO, prepared for the 2014 International Petroleum Technology Conference, Kuala Lumpur, 10–12 December. The paper has not been peer reviewed. A matured field is currently producing with greater than 85% water cut (WC) and has significant levels of uncertainty with respect to oil/water contact (OWC), flank structure, depth of spill points, production allocation, and residual oil saturation. A robust work flow was developed to identify infill opportunities by integrating material-balance study, cased-hole-log information, water diagnostic plots, decline-curve analysis, and other information. The comprehensive locate-the-remaining-oil (LTRO) methodologies applied have been successful and have helped to estimate the potential reserves as well. Introduction The field is 20 km offshore Sarawak, Malaysia, in water depths of 100 ft. The field structure consists of a 30,000×9,000-ft elongated anticline running northeast/southwest and comprises a series of stacked reservoirs at a depth of 4,000 to 9,500 ft. The field is considered structurally simple, with a normal growth fault affecting only the deep reservoirs and no other faults visible on 2D seismic or in the wells. The field reservoirs were deposited during the Late Miocene in a lower coastal plain to the coastal environment. The depositional environment of this field is dominated by a sequence of shore-face deposits. Sands are loosely consolidated, fine- to very-fine-grained, and interbedded with layers of silts and clays. Porosity ranges from 14 to 26%, with a fieldwide mean of 20%. The permeabilities are on the order of 50 to 3,000 md. Net sand thicknesses are less than 30 ft, with most individual sands at approximately 10 ft. The reservoirs are subdivided into three categories: Shallow reservoirs at depths of 4,000 to 5,300 ft are characterized by large gas caps and mostly thin oil rims and are currently considered unfaulted. Main reservoirs at depths of 5,300 to 6,000 ft with no gas caps are also currently considered unfaulted. Deep reservoirs at depths of 6,000 to 9,500 ft can carry high pressures and are dissected by a northwestheaded growth fault with possible associated additional faulting.

Strain rate dependent calcite microfabric evolution – An experiment carried out by nature

A flanking structure developed along a secondary shear zone in calcite marbles, on Syros (Cyclades, Greece), provides a natural laboratory for directly studying the effects of strain rate variations on calcite deformation at identical pressure and temperature conditions. The presence and rotation of a fracture during progressive deformation caused extreme variations in finite strain and strain rate, forming a localized ductile shear zone that shows different microstructures and textures. Textures and the degree of intracrystalline deformation were measured by electron backscattered diffraction. Marbles from the host rocks and the shear zone, which deformed at various strain rates, display crystal-preferred orientation, suggesting that the calcite preferentially deformed by intracrystalline-plastic deformation. Increasing strain rate results in a switch from subgrain rotation to bulging recrystallization in the dislocation-creep regime. With increasing strain rate, we observe in fine-grained (3 μm) ultramylonitic zones a change in deformation regime from grain-size insensitive to grain-size sensitive. Paleowattmeter and the paleopiezometer suggest strain rates for the localized shear zone around 10−10 s−1 and for the marble host rock around 10−12 s−1. We conclude that varying natural strain rates can have a first-order effect on the microstructures and textures that developed under the same metamorphic conditions.

Review of flanking structures in meso- and micro-scales

AbstractA variety of host-fabric elements (HE) cut by cross-cutting elements (CE) in rocks defines flanking structures (FS) on mesoscopic and microscopic scales. There has been renewed interest in studying and classifying the FS for their morphologies, useful as shear sense indicators and geneses. Existing non-genetic morphologic parameters for the FS are reviewed, and two new classification schemes are presented. One of these is based on the nature of the CE and whether HE penetrates it. The other scheme takes account of all the potential combinations of drag/no drag and slip/no slip of the HE. Deciphering the shear sense of the rock body from FS is complicated because the angular relationship between the CE and the primary shear planes might be opposite to what is found between S- and C- ductile shear fabrics. Further, single CEs can curve and several similar FS occur in reverse forms. As with mineral fish, the shape asymmetries of microscopic CEs indicate the shear sense. Conjugate FS (with non-parallel CEs) with interfering perturbation fields around the CEs are more reliable shear-sense indicators than FS with single CE. During low but increasing bulk strains, FS may evolve from one type to another, e.g. from a- to s-type. At high strain, FS can resemble intrafolial or sheath fold. Whether the drag is normal or reverse depends fundamentally on the initial angle between the HE and the CE and the relative magnitudes of throw and vertical separation.

Random coil structures in bacterial proteins. Relationships of their amino acid compositions to flanking structures and corresponding genic base compositions

In this study we classified regions of random coil into four types: coil between alpha helix and beta strand, coil between beta strand and alpha helix, coil between two alpha helices and coil between two beta strands. This classification may be considered as natural. We used 610 3D structures of proteins collected from the Protein Data Bank from bacteria with low, average and high genomic GC-content. Relatively short regions of coil are not random: certain amino acid residues are more or less frequent in each of the types of coil. Namely, hydrophobic amino acids with branched side chains (Ile, Val and Leu) are rare in coil between two beta strands, unlike some acrophilic amino acids (Asp, Asn and Gly). In contrast, coil between two alpha helices is enriched by Leu. Regions of coil between alpha helix and beta strand are enriched by positively charged amino acids (Arg and Lys), while the usage of residues with side chains possessing hydroxyl group (Ser and Thr) is low in them, in contrast to the regions of coil between beta strand and alpha helix. Regions of coil between beta strand and alpha helix are significantly enriched by Cys residues. The response to the symmetric mutational pressure (AT-pressure or GC-pressure) is also quite different for four types of coil. The most conserved regions of coil are "connecting bridges" between beta strand and alpha helix, since their amino acid content shows less strong dependence on GC-content of genes than amino acid contents of other three types of coil. Possible causes and consequences of the described differences in amino acid content distribution between different types of random coil have been discussed.