Lateral Correlation Research Articles

Analyzing the surface dynamics of titanium thin films using fractal and multifractal geometry

Titanium thin films are prepared by DC magnetron sputtering on the glass substrate with varying sputtering power. The nanoscale surface morphology and nanotexture are captured via atomic force microscopy (AFM). The value of average roughness and interface width show the increasing trend with sputtering power. The autocorrelation and height-height correlation function are applied to characterize the formation of the self-affine and mounded surfaces. The roughness (or Hurst) exponent and fractal dimension are estimated by height-height correlation function while lateral correlation length is measured by autocorrelation. It is found that the surface complexity is affected with various sputtering power. The value of Hurst exponent of the topography greater than 0.5 indicates a persistent behavior and such system shows memory effect. The fractal lacunarity, succolarity and surface entropy is used for investigating the surface microtexture and percolation. The 2D Multifractal Detrended Fluctuation Analysis (2D MFDFA) method is used to study the multifractal nature of thin-film surfaces. Computed Δα and Δf show an increase with sputtering power indicating a surface with many characteristic scale patterns. Furthermore, the thin film deposited with the highest sputtering power has greater topographic uniformity, lower surface percolation and greater homogeneity of the surface microtexture.

Segmenting Star Images with Complex Backgrounds Based on Correlation between Objects and 1D Gaussian Morphology

Space object recognition in high Earth orbits (between 2000 km and 36,000 km) is affected by moonlight and clouds, resulting in some bright or saturated image areas and uneven image backgrounds. It is difficult to separate dim objects from complex backgrounds with gray thresholding methods alone. In this paper, we present a segmentation method of star images with complex backgrounds based on correlation between space objects and one-dimensional (1D) Gaussian morphology, and the focus is shifted from gray thresholding to correlation thresholding. We build 1D Gaussian functions with five consecutive column data of an image as a group based on minimum mean square error rules, and the correlation coefficients between the column data and functions are used to extract objects and stars. Then, lateral correlation is repeated around the identified objects and stars to ensure their complete outlines, and false alarms are removed by setting two values, the standard deviation and the ratio of mean square error and variance. We analyze the selection process of each thresholding, and experimental results demonstrate that our proposed correlation segmentation method has obvious advantages in complex backgrounds, which is attractive for object detection and tracking on a cloudy and bright moonlit night.

Experimental Study on Blockage Mechanism and Blockage Locations for Polymer-Flooded Reservoirs in the Henan Oilfield

To address the issues of reservoir blockage and sharp decline in fluid output of production wells in the polymer injection zone of the Henan oilfield, physical modeling has been used to study the blockage mechanism and blockage locations of the polymer-flooded reservoir based on oil reservoir characteristics and blockage knowledge. The results show that all the constant pressures in the low, moderate, and high permeability cores subjected to polymer injection and subsequent waterflooding were higher than the constant pressure during primary waterflooding; hence, polymer retention and blockage phenomena were obvious in the cores; in the high permeability core, the pore surface adsorbed more polymer molecules though pore throat radii were still much greater than the size of the polymer molecule, suggesting that polymer blockage is mainly caused by adsorption and retention. For the low permeability core, the specific surface area of the inlet end was much larger than that in the high permeability core, leading to more serious capture of polymer molecules at the small pores, indicating that blockage under polymer injection is mainly caused by capture and retention; for the lower permeability (91.81 mD) core, as compared with the case prior to polymer injection, the polymer-injected core had fewer large pores and throats, the mean pore throat radius decreased from 42.2 μm to 39.9 μm, and the mean throat-to-pore coordination number decreased from 3.36 to 3.19; thus, polymer capture and retention led to core blockage; the leftward shift of the curve corresponding to the porosity component, high porosity peak weakening after polymer injection, moderate and low porosity peaks appearing after polymer injection, and enhancement of lower porosity peaks indicate that, after polymer injection and subsequent waterflooding, polymer adsorption and capture led to blockage of some large pores; the highest pressure gradient, i.e., 6.3 MPa/m, was achieved at the P2-P3 segment; thus, the worst blockage occurred at the P2-P3 stage, or 1/8-1/4 of the sandpack length. In this paper, Nanbaxian oil and gas field, China, was taken as an example to investigate the interpretation method of gas saturation in a complex pore structure. The “four properties” relationship of the formation reservoir in the Nanbaxian oil and gas field was studied in depth according to the conventional logging data and core analysis data. The neural network algorithm was used to reconstruct the resistivity curve of the water layer to eliminate the influence of lithology, shale content, and pore structure on the resistivity. The difference between the reconstructed curve and the measured resistivity curve was used to identify the gas and water, and the ratio of the two was used to calculate the gas saturation, and good results were achieved. It was found that the sedimentary types of the Nanbaxian oil and gas field cause the reservoir to be thin, numerous, and dispersed; the lateral correlation is difficult. In addition, the structural features lead to the reservoir types being various in the vertical direction, which makes the identification of reservoir fluid more difficult. The results revealed that the rock compaction, poor physical properties, complex pore structure, high resistivity of surrounding rocks, and low formation water salinity make the water layer with high resistivity and difficult to identify gas and water.

Horizontal Correlation of Long-Range Bottom Reverberation in Shallow Sloping Seabed

The performance of active sonar detection systems is seriously affected by the reverberation at the bottom of the waveguide in shallow water. In order to improve the performance of active sonar detection, it is necessary to understand the horizontal correlation of shallow-water bottom reverberation in active towed-array processing technology. However, the current research on the spatial correlation of reverberation is mainly based on vertical correlation, little work has been done on the horizontal correlation characteristics of long-distance seabed reverberation, and there is no support from sea test data. In this paper, the coupled mode reverberation model is applied to the horizontal correlation, and is studied according to the receiving position, time, and frequency. The simulation results show that, for the long-range bottom reverberation, the lateral correlation is greater than the longitudinal correlation in the horizontal space. By introducing the adiabatic mode solution, the mathematical model of horizontal correlation in the range-dependent waveguide with depth is derived. The numerical results show that the influence of the seabed dip angle on the horizontal correlation should be considered and that the horizontal correlation is affected obviously by the propagation effects of the sloped sea floor. Finally, the experimental data processing and analysis are given and verify the correctness of the algorithm.

Jurassic-Cretaceous Red beds of the southern Front of Moroccan Central High Atlas (Aghbalou N'Kerdouss-Tadighoust region): Sedimentological, lithostratigraphical and paleogeographical studies

Sedimentologic and lithostratigraphic studies carried out along the southern Front of the Central High Atlas in a mostly terrigenous Jurassic-Cretaceous series (Red beds) allow specifying the paleoenvironmental and paleogeographic evolution of three units: Guettioua, Ifezouane and Aoufous formations. The Bathonian Guettioua Fm, composed of terrigenous deposits of a median-distal piedmont and a proximal alluvial plain, is arranged into a regressive mesosequence. A terrigenous Lower (Mbr1) and an Upper (Mbr3) members of the Ifezouane Fm (Albian?-Cenomanian) were deposited in a median to a distal alluvial plain. Paleocurrent analysis indicates a southern source area of the terrigenous material mainly resulting from erosion of the neighbouring or distant Precambrian and Paleozoic basement. The southern origin of the material is opposite to a northern source proposed by authors for the surrounding western areas. These terrigenous supplies are interspersed with a lagoonal-marine incursion that covered the region during the deposition of a Middle Member (Mbr2) of the Ifezouane Fm. Fossiliferous limestone layers have yielded a restricted euryhaline microfauna and macrofauna. This restricted lagoon, E-W oriented with a multi-kilometre extension, was probably opened towards the East. By lateral correlations, this lagoonal-marine event can be dated to the Albian? - Cenomanian interval. This Cretaceous transgression, well documented for the first time, belongs to an earlier mesosequence recorder before the widespread and well-known Upper Cenomanian-Turonian transgression.

Application of electron tomography for comprehensive determination of III-V interface properties

We present an electron tomography method for the comprehensive characterization of buried III-V semiconductor interfaces that is based on chemical-sensitive high-angle annular dark-field scanning transmission electron microscopy. For this purpose, an (Al,Ga)As/GaAs multi-layer system grown by molecular beam epitaxy is used as a case study. Isoconcentration surfaces are exploited to obtain topographic height maps of 120 nm × 120 nm area, revealing the interface morphology. By applying the height-height correlation function, we are able to determine important interface properties like root mean square roughness and lateral correlation length of various interfaces of the (Al,Ga)As/GaAs system characterized by different Al concentrations. Height-difference maps based on isosurfaces corresponding to 30% and 70% of the total compositional difference at the interfaces are used to create topographic maps of the interface width and to calculate an average interface width. This methodology proves differences in the properties of direct and inverted interfaces and allows the observation of interfacial anisotropies.

Facies analysis of a Bartonian–Aquitanian siliciclastic‑carbonate system, Costa Rica

Costa Rican Eocene–Oligocene carbonate deposits have been known for more than a hundred years, however, there are few scientific contributions detailing the relation between facies analysis and regional basin evolution. Based on a detailed study in southern Costa Rica, a chronologic history of a Bartonian–Aquitanian sedimentary succession is proposed. The carbonate facies analysis allows for eight microfacies (MF1 to MF8) to be distinguish. The siliciclastic facies analysis permits identification of two main periods of sandstone deposition and one of shale formation. The mixed sandstone/carbonate succession exhibits three main periods of deposition: (1) Bartonian–lower Priabonian, represented by distal, relatively deep slope-to-basin environments. Deposits comprise thick accumulation of sandstones, calcareous breccias, and calciturbidites. This period terminates with a stratigraphic erosion surface; (2) Upper Priabonian–Rupelian, represented by more proximal, shallow to mid depth inner to middle ramp environments. Deposits are composed of peloidal/cortoidal grainstone, foraminiferal-algal rudstones, and rhodolith rudstones. This period terminates with a second stratigraphic erosion surface; (3) Chattian–Aquitanian, represented by proximal to distal, shallow to coastal and offshore environments. Deposits are composed of a mixed siliciclastic carbonate thin complex overlain by dark shale.The vertical and lateral facies changes permit a basin evolution model that is closely controlled by subsidence. Local tectonic uplift may have formed the first subaerial exposure surface. The second subaerial exposure surface may have been controlled by eustatic sea-level variations over relatively shallow water deposits. These results, the first-of-their-kind in the southern Costa Rican Fila Costeña, could permit improvements of lateral regional correlations by bringing new lithostratigraphic layers of reference.

Stratigraphy and U–Pb geochronology of the basal units of the vazante group: A lateral correlation with the glaciogenic Jequitaí formation (Minas Gerais, Brazil)

The basal units of the Vazante Group, the Santo Antônio do Bonito and Rocinha formations, present different stratigraphic records and younger ages than the rest of the group. These units are characterized by diamictites, sandstones, pelites and rare carbonates originated from subaqueous gravitational sedimentation. U–Pb geochronological data in detrital zircon indicate a Tonian maximum depositional age for both formations. The youngest zircon grains yielded ages ranging from 903 to 935 Ma. The main source for zircon is Paleoproterozoic (mainly Rhyacian and Orosirian) to Mesoproterozoic (Calymmian and Ectasian) areas being probably the São Francisco paleocontinent the main area. Due to the complete absence of ice-rafted debris within fine-grained sediments in the Santo Antônio do Bonito Formation, we interpret a gravitational reworking as the main process of diamictites deposition, probably during a period of ice retreat and sea level rise. The U–Pb data corroborate a lateral correlation between the Santo Antônio do Bonito and Rocinha formations with the glaciogenic Jequitaí Formation (Bambuí Group). From east to west, glacial sediments of the Jequitaí Formation were reworked probably by a slope-apron system during a late-glacial to post-glacial stage on the western margin of the São Francisco paleocontinent. Therefore, the Vazante Group can be divided into two successions: the upper Lagamar-Serra do Garrote formations and the lower Santo Antônio do Bonito-Rocinha formations. The Lagamar-Serra do Garrote sedimentation comprises a late Mesoproterozoic mixed carbonate-siliciclastic deposition in passive margins. The second succession is a gravitational slope-apron resedimentation and probably correlates with the Neoproterozoic glacial rocks of the Jequitaí Formation from the Bambuí Group. Finally, the collisional phase of the Brasília Belt was responsible for stratigraphic inversion, placing the older Lagamar-Serra do Garrote formations over the younger Santo Antônio do Bonito-Rocinha formations.

Integrated lateral correlation of tsunami deposits during the last 6000 years using multiple indicators at Koyadori, Sanriku Coast, northeast Japan

Tsunami deposit studies have progressed and provided extensive information on the presence of tsunami deposits, their ages, and physical parameters especially after the devastating tsunamis from the 2004 Sumatra earthquake and 2011 Tohoku-oki earthquake. However, the abundance of such information makes it challenging to assess its uncertainty and reliability. These issues associated with the tsunami deposit studies are significant and should be resolved for the benefit of people using tsunami deposit data. In this study, we used multisite drilling cores to elucidate the sediment distribution in the study area. Additionally, we conducted micro-X-ray fluorescence core scanning, roundness analysis, and radiocarbon dating to obtain a certain identification of tsunami deposits and a reliable lateral correlation of sediments. Herein, we present a long-term tsunami history and tsunami deposit distribution at Koyadori on the Sanriku Coast in northeast Japan. Adding to tsunami deposits including the 2011 CE tsunami deposits reported in our previous studies, three tsunami deposits widely distributed in the Koyadori lowland were newly identified, concluding 14 tsunami deposits during the last 6000 years. This continuous and long record of large tsunamis in the central part of the Sanriku Coast provides an insight into the mechanisms of earthquakes and tsunamis occurring in the Japan Trench and is also expected to contribute to improvement in hazard assessment of earthquakes and tsunamis. Quantitative data (geochemical signature and gravel roundness) are also useful for a lateral correlation of tsunami deposits. In addition, the correlated sediment distribution enables the identification of an area with high preservation potential of tsunami deposits and estimation of paleoenvironment since 6 ka. Therefore, detailed information on tsunami deposits in one area is as necessary as revealing tsunami deposits across a wider area for future studies.

Cyclicity and hierarchy in sequence stratigraphy: an integrated approach

With standardized methodology and nomenclature, the sequence stratigraphy aims to characterize multi-scale cyclical units of genetically related rocks into a hierarchical chronostratigraphic framework. From facies to basin scale, the stacking patterns and stratigraphic surfaces are recognized as sequence elements. In parallel, Earth sciences have developed a sophisticated understanding of geological processes (tectonic, climatic, and eustatic) that produce the main cyclicity observed in the sedimentary rock record. This review paper discusses how the elaboration of hierarchical stratigraphic frameworks that incorporate the knowledge of these periodic geological processes — from high- to low-frequencies — as the control of generation and preservation of sequences — from high- to low-resolutions — guarantees objective results in predicting vertical recurrence and the lateral correlation of genetic stratigraphic units. This interpretive approach of cyclic stratigraphic analysis supports the development of effective observable criteria to identify and rank sequences in multiple scales, based on cycle anatomy, recurrence, vertical trends, and mappability. This methodological improvement reduces the inaccuracies and contradictions of traditional conceptual models based on fully preserved three-dimensional depositional systems.

Microstructure Determines Apparent-Level Mechanics Despite Tissue-Level Anisotropy and Heterogeneity of Individual Plates and Rods in Normal Human Trabecular Bone.

Trabecular plates and rods determine apparent elastic modulus and yield strength of trabecular bone, serving as important indicators of bone's mechanical integrity in health and disease. Although trabecular bone's apparent-level mechanical properties have been widely reported, tissue mechanical properties of individual trabeculae have not been fully characterized. We systematically measured tissue mineral density (TMD)-dependent elastic modulus of individual trabeculae using microindentation and characterized its anisotropy as a function of trabecular type (plate or rod), trabecular orientation in the global coordinate (longitudinal, oblique, or transverse along the anatomic loading axis), and indentation direction along the local trabecular coordinate (axial or lateral). Human trabecular bone samples were scanned by micro-computed tomography for TMD and microstructural measurements. Individual trabecula segmentation was used to decompose trabecular network into individual trabeculae, where trabecular type and orientation were determined. We performed precise, selective indentation of trabeculae in each category using a custom-built, microscope-coupled microindentation device. Co-localization of TMD at each indentation site was performed to obtain TMD-to-modulus correlations. We found significantly higher TMD and tissue modulus in trabecular plates than rods. Regardless of trabecular type and orientation, axial tissue modulus was consistently higher than lateral tissue modulus, with ratios ranging from 1.13 to 1.41. Correlations between TMD and tissue modulus measured from axial and lateral indentations were strong but distinct: axial correlation predicted higher tissue modulus than lateral correlation at the same TMD level. To assess the contribution of experimentally measured anisotropic tissue properties of individual trabeculae to apparent-level mechanics, we constructed non-linear micro-finite element models using a new set of trabecular bone samples and compared model predictions to mechanical testing measurements. Heterogeneous anisotropic models accurately predicted apparent elastic modulus but were no better than a simple homogeneous isotropic model. Variances in tissue-level properties may therefore contribute nominally to apparent-level mechanics in normal human trabecular bone. © 2021 American Society for Bone and Mineral Research (ASBMR).

Effects of lacustrine depositional sequences on organic matter enrichment in the Chang 7 Shale, Ordos Basin, China

Chang 7 Shale, characterized by lacustrine black organic-rich shales and interbedded siltstones, has become a target for shale oil exploration and development in the Upper Triassic Ordos Basin, China. However, the heterogeneous enrichment of organic matter (OM) has led to controversy regarding source rock evaluation and difficulty in accurate prediction of favorable zones. Sequence stratigraphy, as a tool for prediction of sedimentary deposits has encountered challenges in lacustrine deep-water environments because of rapid facies changes and limited lateral continuity of key beds. In this study, a novel method is proposed to predict OM enrichment based on parasequences division and calibration of well logging and core lithology through analyses of thin sections and geochemical data from 238 core samples, as well as available well-logging data from a selected well. Chang 7 shales were simplified into three facies in terms of sedimentary structure and mineral composition, combining geological genesis with lateral correlation. Argillaceous laminated shale (Facies 2), with the highest average total organic carbon and S1 + S2 values, is the most favorable facies for shale oil exploration. The Chang 7 Member was divided into 15 parasequences and six parasequence sets, within one transgressive-regressive sequence. Depositional sequences have a significant effect on the enrichment of OM, given 1) the influence of lake-level fluctuations on OM accumulation, 2) the OM enrichment determined by shale facies, and 3) the distribution of shale facies controlled by parasequences. In particular, the most favorable locations are the bases of parasequences (generally the lower third to half from the bottom) in the TST and early RST. The application of this method to a test well showed excellent performance based on verification from the organic geochemical data of 86 samples. Five favorable targets of Facies 2 were marked within fifteen favorable locations. By linking meter-level depositional sequences with centimeter-level OM enrichment, this study provides an alternative approach to determine the target area in a single well profile and realize isochronous inter-well prediction for deep-water shales.

A test of the lateral semicircular canal correlation to head posture, diet and other biological traits in \u201cungulate\u201d mammals

For over a century, researchers have assumed that the plane of the lateral semicircular canal of the inner ear lies parallel to the horizon when the head is at rest, and used this assumption to reconstruct head posture in extinct species. Although this hypothesis has been repeatedly questioned, it has never been tested on a large sample size and at a broad taxonomic scale in mammals. This study presents a comprehensive test of this hypothesis in over one hundred “ungulate” species. Using CT scanning and manual segmentation, the orientation of the skull was reconstructed as if the lateral semicircular canal of the bony labyrinth was aligned horizontally. This reconstructed cranial orientation was statistically compared to the actual head posture of the corresponding species using a dataset of 10,000 photographs and phylogenetic regression analysis. A statistically significant correlation between the reconstructed cranial orientation and head posture is found, although the plane of the lateral semicircular canal departs significantly from horizontal. We thus caution against the use of the lateral semicircular canal as a proxy to infer precisely the horizontal plane on dry skulls and in extinct species. Diet (browsing or grazing) and head-butting behaviour are significantly correlated to the orientation of the lateral semicircular canal, but not to the actual head posture. Head posture and the orientation of the lateral semicircular canal are both strongly correlated with phylogenetic history.

Quantitative assessment of human cervix with correlation length ratio during pregnancy: An in vivo longitudinal study

We recently introduced a novel parameter called the correlation length ratio (CLR), a ratio of lateral to axial correlation lengths for backscattered echo signals, to detect the presence of elongated structures in soft tissues. Here, we look at variation of CLR and presence of elongated structures in human cervix during pregnancy using a longitudinal data from a group of women with normal pregnancy. Thirty women, ages ranging from 19 to 37years, were scanned with ultrasound at five time points beginning at their normal first-trimester screening (8 –13 weeks) through term pregnancy (nominally 40 week). We computed correlation lengths, and CLR. To account for the system point spread function, an empirical cumulative distribution function of the CLR was obtained from a reference phantom. A one-sided threshold of 95% of the CDF was then computed. The difference between CLR in the sample and the threshold was computed and its variation with increasing gestational age was obtained. CLR estimation demonstrated a gradient along the length of the cervix. This longitudinal study also demonstrated an increase of about 0.5% (per week) in lateral correlation length and 0.8% increase in CLR with increasing gestational age, while axial correlation length was almost constant.

Determination of geological structures by geophysical and geotechnical techniques in Kırklartepe Dam Site (Turkey)

In foundation research of engineering structures, application of geophysics methods before drilling work allows not only more economical studies but also a more detailed determination of underground sections. Especially in pre-feasibility studies on long tunnel routes, dam sites and lake areas, it has a vital importance in terms of structural safety to determine possible underground buried fault lines, lithology changes, anticlinal-synclinal structures and underground openings. By considering these effective factors, the alluvium/bedrock border and the positions of potential buried faults in the dam site and lake area in the Kırklartepe area of the province of Bayburt in northeastern Turkey were determined by comparison with geophysical and geotechnical methods. First of all, the resistivity of the dam axis location and the change of the Vp wave velocity by depth were determined by comparing the results between geophysical methods of electrical resistivity tomography (ERT) and seismic refraction tomography (SRT), respectively. Afterwards, from the foundation boreholes opened in the dam axis location, joint frequency and the other parameters determined by observations were obtained. With these parameters, 2-dimensional zoning profiles of the dam axis location were formed, and the alluvium-bedrock border and the locations of the buried faults were determined. Two potential faults in the NW-SE direction relative to the location of the dam axis were clearly revealed in the zoning profiles obtained in the ERT and SRT measurements. Additionally, the presence of these faults was determined as a result of examining the separation and joint frequency parameters from the drilling core samples collected from the BH_3 and BH_5 boreholes opened in the investigated area based on changes in the vertical and horizontal directions. In addition to these, in the ERT study, two potential faults other than the determined two were also detected. It was seen in the zoning profiles that these faults corresponded to right under the BH_2 borehole and 60 m SW of the BH_6 drilling. Consequently, in the zoning studies conducted at the examined site, the change in the lithology at the dam axis by depth (alluvium-bedrock border), lateral correlations of boreholes and potential faults were determined. It was recommended for the selected dam axis location to be constructed at a more suitable place in the NW direction in terms of engineering. Furthermore, with this study, it was revealed once again that it is highly essential to use geophysical and geotechnical together in conceptualizing large engineering structure projects.

Real-time tracking of the self-assembled growth of a 3D Ge quantum dot lattice in an alumina matrix

A laboratory in situ grazing-incidence small-angle X-ray scattering (GISAXS) tracking of the self-assembled growth of a regular 3D Ge quantum dot (QD) structure in an amorphous Al2O3 matrix during the ion beam sputter deposition of a periodic Ge/Al2O3 multilayer on silicon is reported. A 573 K substrate temperature proved to be necessary to achieve the self-assembly effect. Relying on a fast repeated acquisition of GISAXS patterns, the temporal evolution of the growing 3D Ge QD structure was analyzed bilayer by bilayer to determine its type, lateral and vertical correlation lengths, and inter-QD distance. The QD structure was found to have body-centered tetragonal lattice type with ABA stacking, with the lattice parameters refined by fitting the final GISAXS pattern relying on a paracrystal model. A single set of paracrystal parameters enables one to simulate the temporal evolution of the in situ GISAXS patterns throughout the deposition process, suggesting that the Ge QD self-assembly is driven from the very beginning solely by the growing surface morphology. Ex situ GISAXS and X-ray reflectivity measurements along with a cross-section high-resolution transmission electron microscopy analysis complete the study.

Geology of the Lower Cretaceous in the Falkebjerg area, Wollaston Forland, northern East Greenland

New data on the Lower Cretaceous Falskebugt Member (Palnatokes Bjerg Formation) and Stratumbjerg Formation in easternmost Wollaston Forland, northern East Greenland, are interpreted here. The type locality of the Falskebugt Member on the north-west corner of the Falkebjerg ridge has been revisited, and additional new good exposures were found in a riverbed just north of Falkebjerg and more in river beds on the plain further to the north, where both the Falskebugt Member and the Stratumbjerg Formation are exposed. Previously, only a limited marine fauna was reported providing a restricted middle Valanginian age of the Falskebugt Member. New fossil faunas in other parts of the Falskebugt Member suggest an early Valanginian – Hauterivian age and confirm lateral correlation with the Albrechts Bugt and Rødryggen Members of the Palnatokes Bjerg Formation. However, in places where the Falskebugt Member is exposed in contact with the lower Stratumbjerg Formation, dinoflagellate cysts from these units indicate Barremian and late Barremian ages, respectively. The stratigraphic range of the combined biostratigraphic data from the Falskebugt Member indicates an early Valanginian – late Barremian age. Dinoflagellate cysts from part of the assemblage in the Stratumbjerg Formation suggest a marginal marine/brackish water depositional environment. Comparable depositional environments are also recorded in upper Barremian sediments on Store Koldewey and in the Ladegårdsåen Formation on Peary Land much farther to the north in Greenland. The dark mudstones of the Stratumbjerg Formation show no potential for generation of liquid hydrocarbons, and the immature and poorly sorted sediments of the Falskebugt Member have little potential as a petroleum reservoir.

Lithological correction of chemical weathering proxies based on K, Rb, and Mg contents for isolation of orbital signals in clastic sedimentary archives

The extraction of palaeoenvironmental (palaeoclimatic) signals from the chemical composition of siliciclastic sediments is valuable for the reconstruction of past environments, particularly in continental basins. Here we test novel weathering proxies, which are less sensitive to lithological control than the previously used raw element ratios K/Al, K/Ti, and K/Rb: (1) local enrichment factors of K/Al, Mg/Al, and K/Rb, i.e., the element ratios corrected for grain size- and matrix composition using local background functions (Al/Si, Fe, and Ca as explanatory variables) and ordinary regression and (2) robust regression residuals of those element ratios based on isometric log-ratio coordinates of the most relevant “lithogenic” elements (Ca, Fe, Rb, Si, Zr) in the chemical composition. Chemical weathering proxies can be obtained from departures of chemical composition of sedimentary profiles from relationships with other chemical elements, in particular those with grain-size control. The resulting weathering proxies were examined for the Miocene deposits from the Most Basin, the Czech Republic, which recorded one of the major warm episodes of the Cenozoic time – the Miocene Climatic Optimum. The performance of weathering proxies has been checked by (1) comparison of individual proposed proxies in one drill core HK930, (2) detailed analysis of orbital signals in the relevant compositional functions in HK930; and (3) lateral correlation of three cores HK930, DU7, and DO565 of the same basin. The novel proxies show lateral stability and orbital signatures of short eccentricity, obliquity, and precession, confirming their usefulness in palaeoenvironmental studies. Corrections for grain-size and carbonate contents should help to isolate climatic content from the weathering proxies, although in the studied sediments it weakened the precession component in the orbital signal, as grain-size proxies and other compositional data also carried orbital signals. We propose to consider these proxy ideas in palaeoclimatic reconstructions based on chemical weathering proxies.

Laterally Resolved Small-Angle Scattering Intensity from Lipid Bilayer Simulations: An Exact and a Limited-Range Treatment.

When combined, molecular simulations and small-angle scattering experiments are able to provide molecular-scale resolution of structure. Separately, scattering experiments provide only intermingled pair correlations between atoms, while molecular simulations are limited by model quality and the relatively short time scales that they can access. Their combined strength relies on agreement between the experimental spectra and those computed by simulation. To date, computing the neutron spectra from a molecular simulation of a lipid bilayer is straightforward only if the structure is approximated by laterally averaging the in-plane bilayer structure. However, this neglects all information about lateral heterogeneity, e.g., clustering of components in a lipid mixture. This paper presents two methods for computing the scattering intensity of simulated bilayers with in-plane heterogeneity, enabling a full treatment of both the transverse and lateral bilayer structure for the first time. The first method, termed the Dirac Brush, computes the exact spectra including spurious artifacts resulting from using information from neighboring periodic cells to account for the long-range structure of the bilayer. The second method, termed PFFT, applies a mean-field treatment in the field far from a scattering element, resulting in a correlation range that can be tuned (eliminating correlations with neighboring periodic images), but with computational cost that prohibits obtaining the exact (Dirac Brush) spectra. Following their derivation, the two methods are applied to a coarse-grained molecular simulation of a bilayer inhomogeneity, demonstrating the contributions of lateral correlations to the resulting spectra.

Scaling study of molecular beam epitaxy grown InAs/Al2O3 films using atomic force microscopy

Scaling study of polycrystalline InAs thin films grown by molecular beam epitaxy on c-plane sapphire (001) substrate has been presented using atomic force microscopy, corresponding height-height correlation function and two-dimensional fast Fourier transform profiles. Height-height correlation function profiles exhibit oscillations at larger lateral distances along with ring-like features in the respective two-dimensional fast Fourier transform scans and clearly indicate mound-like surface morphology. Scaling parameters, interface width and lateral correlation length were extracted and their dependence on the growth temperatures were investigated. The growth mechanism has been well explained in terms of diffusion effects and the obtained parameters qualitatively agrees with the parameters obtained for the growth of InAs films grown on Si(100) substrate under identical growth conditions. Our study suggests that molecular beam epitaxy grown InAs thin films on lattice mismatched substrates (c-plane sapphire(001) and Si(100) substrate) follows the same growth behavior under identical growth conditions.