bluuebunny/crossref_metadata_2025 huggingface dataset:
Coseismic extension recorded within the damage zone of the Vado di Ferruccio Thrust Fault, Central Apennines, Italy
Authors: Leah Harold , Fondriest Michele , Lucca Alessio , Storti Fabrizio , Balsamo Fabrizio , Di Toro Giulio
Published: July 2018

Recent high resolution hypocentral localisation along active fault systems in the Central Apennines illuminates the activation of seismogenic volumes dipping at low angle (<30°) in extensional settings overprinting contractional deformations affecting the continental crust of the Adria microplate. Individuation of the geological structures and of the fault processes associated with these seismic patterns will contribute to the interpretation of seismic sequence evolution, and seismic hazard studies.Here we report field and microstructural evidence of seismogenic extensional faults localized within pre-existing thrust fault zones. The Vado di Ferruccio Thrust Fault (VFTF) is a narrow fault zone (<2.5 m thick fault core) in the Central Apennines of Italy, accommodating ∼1 km of shortening during Miocene-Pliocene and exhumed from <3.5 km depth. In the thrust zone, exposures throughout the Fornaca Tectonic Window show Late Triassic bituminous dolostones thrust over Middle Jurassic interlayered carbonates upon a SSW-dipping fault. Isoclinal folds are dragged and sheared by thrust-parallel reverse faults in the footwall block whereas NW-striking faults occur within the hanging wall. Fault core observations are consistent with stable pressure solution-mediated aseismic sliding towards N024° during thrusting, with cyclic veining and faulting. Later extension has been accommodated at the regional scale by major normal faults cutting through the VFTF, while veins and pressure-solution seams crosscut the microstructures associated with thrusting and record the extensional stress regime within the thrust fault core. Lenses of shattered rocks (up to 10 s m thick), cut by a dense network of small displacement (<1.2 m) mirror-like normal faults, are reported in the hangingwall of the VFTF. These minor faults, related to a sharp principal slipping surface on the upper margin of the VFTF fault core, are interpreted as fossil evidence of microseismicity compartmentalized within the hanging wall of the VFTF. Synthetic and antithetic normal faults within the VFTF hangingwall damage zone are geometrically and kinematically similar to small earthquake ruptures (Mw < 2) in the hangingwall of low angle structures such as the thrust flats illuminated during the 2009 Mw 6.1 LAquila seismic sequence.
Present-day stress orientations in the Great Sumatran Fault in North Sumatra
Authors: Fernández-Blanco David , Philippon Mélody , von Hagke Christoph
Published: July 2018

Trench-parallel strike slip faults develop at lithospheric scale during oblique high-angle subduction. A “sliver” plate forms due to slip partitioning between the subduction plane (margin-normal slip) and the strike slip fault (margin-parallel slip). This process ultimately controls the location of volcanoes and earthquakes. The Great Sumatran Fault (GSF) is a showcase of this tectonic configuration located in the Sumatran section of the Sunda arc-trench system. Kinematics of the large-scale structures of the Sumatra section of the Sunda trench are well understood and tensional and compressional domains have been identified at the regional scale. However, detailed understanding of the stress distribution is still lacking yet essential for evaluating the seismic hazard potential in order to mitigate the impact of the large, hazardous earthquakes associated with this system.In this contribution, we study the present-day stress orientations of the Great Sumatran Fault at its northern section (NGSF). We deduced the state of (paleo)stress along structural features observed at two scales; (a) at meso-scale, analyzing ASTER GDEM data, and (b) at outcrop-scale, with field data measurements. We focus on the leading edge of northwestward propagating continental sliver deformation exposed on land, i.e. the northernmost tip of Sumatra (between 4,5°N and 6°N), where the NGSF bifurcates into its two major branches. These two fault branches form two structural highs bounding a graben basin in the onshore, continuing into the Pulau Weh Island in the east, and the Pulau Aceh Archipelago in the west. Given their location at the present day deformation front, these islands provide a unique opportunity to compare the sub-recent stress field with present day stresses, contributing to the understanding of the stress field evolution during northwestwards propagation of the Sumatran forearc continental sliver.
Using climate to relate water-discharge and area in modern and ancient catchments
Authors: Eide Christian , Müller Reidar , Helland-Hansen William
Published: July 2018

Models relating sediment-supply to catchment-properties are important in order to use the geological record to deduce landscape evolution and the interplay between tectonics and climate. Water-discharge (Qw) is an important factor in the widely used BQwART-model of Syvitski and Milliman (2007), which relates sediment load to a set of measureable catchment parameters. Although many of the factors in this equation may be independently estimated with some degree of certainty in ancient systems, water-discharge (Qw) certainly cannot. An analysis of a world database of modern catchments (Milliman and Farnsworth, 2011) shows that the commonly applied equation relating catchment area (A) to water-discharge (Qw=0.075A0.8), does not predict water-discharge from catchment area well in many cases (R2=0.5 and an error spanning 4 orders-of-magnitude). Neither does the equation incorporate the effect of arid and wet climate on this relationship. The inclusion of climate-data into such estimations is an opportunity to refine these estimates, because generalized estimates of palaeoclimate can often be deduced on the basis of sedimentological data such as palaeosol types, mineralogy and palaeohydraulics.This paper investigates how the relationship between catchment size and river discharge vary with four runoff categories (arid, subarid, humid, and wet) which are recognizable in the geological record, and modify the coefficient and exponent of the abovementioned equation according to these classes. It follows from this analysis that water-discharge from arid catchments is so variable, that water-discharge cannot be predicted from catchment area. Our modified model yields improved results in relating discharge to catchment size (R2=0.95 and error spanning 1 order-of-magnitude) when core-, outcrop- or regional palaeoclimate reconstruction data are available in non-arid systems. In conclusion, this model, in contrast to the previous, is sufficient for many geological applications and will lead to a higher degree of confidence in the application of mass-balance models in ancient systems.
Active deformation of Malawi Rift’s North Basin hinge zone modulated by reactivation of pre-existing Precambrian shear zone fabric
Authors: Kolawole Folarin , Atekwana E. , Lao-Davila Daniel , Abdelsalam M. , Chindandali P. , Salima J. , Kalindekafe L.
Published: July 2018

Key Points:1. Filtered aeromagnetic data elucidates the relationship between earthquake surface ruptures and buried faults along the North Basin hinge-zone, Malawi Rift.2. Fault segments align with basement shear zone fabric.3. Strain accommodation in the North Basin hinge zone is modulated by reactivation of the underlying Precambrian shear zone fabric. Abstract:We integrated temporal aeromagnetic data and recent earthquake data to address the long-standing question on the role of pre-existing Precambrian structures in modulating strain accommodation and subsequent ruptures leading to seismic events within the East African Rift System (EARS). We used aeromagnetic data to elucidate the relationship between the locations of the 2009 Mw 6.0 Karonga, Malawi earthquake surface ruptures and buried basement faults along the hinge zone of the half-graben comprising the North Basin of the Malawi Rift. Through the application of derivative filters and depth-to-magnetic-source modeling, we identified and constrained the trend of the Precambrian metamorphic fabrics and correlated them to the three-dimensional (3D) structure of buried basement faults. Our results reveal an unprecedented detail of the basement fabric dominated by high frequency WNW- to NW-trending magnetic lineaments associated with the Precambrian Mughese Shear Zone fabric. The high frequency magnetic lineaments are superimposed by lower frequency NNW-trending magnetic lineaments associated with possible Cenozoic faults. Surface ruptures associated with the 2009 Mw 6.0 Karonga earthquake swarm aligned with one of the NNW-trending magnetic lineaments defining a normal fault that is characterized by right-stepping segments along its northern half and coalesced segments on its southern half. Fault geometries, regional kinematics and spatial distribution of seismicity suggest that seismogenic faults reactivated the basement fabric found along the half-graben hinge zone. We suggest that focusing of strain accommodation and seismicity along the half-graben hinge zone is facilitated and modulated by the presence of the basement fabric.
Missing emissions from post-monsoon agricultural fires in northwestern India: regional limitations of MODIS burned area and active fire products
Authors: Liu Tianjia , Marlier Miriam , Karambelas Alexandra , Jain Meha , Singh Sukhwinder , Singh Manoj , Gautam Ritesh , DeFries Ruth
Published: July 2018

A rising source of outdoor emissions in northwestern India is crop residue burning, occurring after the monsoon (kharif) and winter (rabi) crop harvests. In particular, post-monsoon rice residue burning, which occurs annually from October to November and is linked to increasing mechanization, coincides with meteorological conditions that enhance short-term air quality degradation. Here we examine the Global Fire Emissions Database (GFED), whose bottom-up emissions are based on the 500-m burned area product, MCD64A1, derived from Moderate Resolution Imaging Spectroradiometer (MODIS) observations. Using a household survey from 2016, we find that MCD64A1 tends to underestimate burned area in many surveyed villages, leading to poor representation of small, scattered fires and consequent spatial biases in model results. To more accurately allocate such small fires and resolve sub-village heterogeneity, we use an experimental hybrid MODIS-Landsat method (ModL2T) to map burned area at 30-m spatial resolution, which results in 44 ± 21% higher burned area than MCD64A1 and up to 105 ± 52% increase in dry matter emissions over GFEDv4s. In our validation and assessments, we find that ModL2T performs better relative to MCD64A1 in terms of bias and omission error, but may introduce commission error due to conflation of burning with harvest and still underestimate burned area due to Landsat’s coarse temporal resolution (every 16 days). We conclude that while MODIS and Landsat provide more than two decades worth of observations, their spatio-temporal resolution is too coarse to overcome several region-specific challenges: small median landholding size (1-3 ha), quick harvest-to-sowing turnover period, prevalence of partial burning, and increasing haziness. To further constrain agricultural fire emissions in northwestern India and improve model estimates of associated public health impacts, integration of finer resolution imagery, as well as better understanding of the spatial patterns in burn rates, burn practices, and fuel loading, is requisite.
Compositional Signatures in Acoustic Backscatter Over Vegetated and Unvegetated Mixed Sand-Gravel Riverbeds
Authors: Buscombe Daniel
Published: July 2018

Multibeam acoustic backscatter has considerable utility for remote characterization of spatially heterogeneous bed sediment composition over vegetated and unvegetated riverbeds of mixed sand and gravel. However, the use of high-frequency, decimeter-resolution acoustic backscatter for sediment classification in shallow water is hampered by significant topographic contamination of the signal. In mixed sand-gravel riverbeds, changes in the abiotic composition of sediment (such as homogeneous sand to homogeneous gravel) tend to occur over larger spatial scales than is characteristic of small-scale bedform topography (ripples, dunes, and bars) or biota (such as vascular plants and periphyton). A two-stage method is proposed to filter out the morphological contributions to acoustic backscatter. First, the residual supragrain-scale topographic effects in acoustic backscatter with small instantaneous insonified areas, caused by ambiguity in the local (beam-to-beam) bed-sonar geometry, are removed. Then, coherent scales between high-resolution topography and backscatter are identified using cospectra, which are used to design a frequency domain filter that decomposes backscatter into the (unwanted) high-pass component associated with bedform topography (ripples, dunes, and sand waves) and vegetation, and the (desired) low-frequency component associated with the composition of sediment patches superimposed on the topography. This process strengthens relationships between backscatter and sediment composition. A probabilistic framework is presented for classifying vegetated and unvegetated substrates based on acoustic backscatter at decimeter resolution. This capability is demonstrated using data collected from diverse settings within a 386 km reach of a canyon river whose bed varies among sand, gravel, cobbles, boulders, and submerged vegetation.
Seismic anisotropy changes across upper mantle phase transitions
Authors: Yuan Kaiqing , Beghein Caroline
Published: July 2018

The mantle transition zone is believed to play an important role in the thermochemical evolution of our planet and in its deep water cycle. Constraining mantle flow at these depths can help elucidate its nature and better understand mantle dynamics and the history of plate tectonics. Seismic anisotropy, i.e., the directional dependence of seismic wave velocity, provides us with the most direct constraints on mantle deformation. Its detection below ∼250km depth is challenging, and it is often assumed that the deep upper mantle is seismically isotropic due to a change in mantle deformation mechanism. Here, we present a global model of azimuthal anisotropy for the top 1000 km of the mantle. We used a dataset composed of fundamental and higher mode Rayleigh wave phase velocity maps, which provides resolution of azimuthal anisotropy to much greater depths than in previous studies. Our model unravels the presence of significant anisotropy in the transition zone, challenging common views of mantle deformation mechanisms, and reveals a striking correlation between changes in anisotropy amplitudes and in the fast direction of wave propagation where upper mantle phase transitions occur. The newly found relation between anisotropy changes and phase transformations gives new insight on the nature of the MTZ and suggests that the anisotropy originates from the lattice preferred orientation of anisotropic material. While the interpretation of our results in terms of mantle deformation is not straightforward due to many possible scenarios, possible explanations for our findings include recrystallization during phase transformations, or changes in the slip system across the MTZ boundaries, which in turn could be explained by changes in the water content of mantle material, consistent with the idea that the transition zone acts as a water filter.
P and S tomography using normal-mode and surface waves data with a neighbourhood algorithm
Authors: Beghein Caroline , Resovsky Joseph , Trampert Jeannot
Published: July 2018

Traditionally P- and S-wave tomography has been based on the inversion of data that are sensitive to the desired Earth structure, and model covariance is estimated from imperfect resolution and data error propagation. This analysis ignores the usually large null-spaces, and hence the significant non-uniqueness of the solution encountered in seismic tomography problems. Here we perform a model space search for P- and S-velocity structure to find acceptable fits to recent normal-mode splitting and fundamental-mode phase velocity data.The survey of the model space employs the neighbourhood algorithm of Sambridge, which preferentially samples the good data-fitting regions. A Bayesian approach is used subsequently to extract robust information from the ensemble of models.We particularly focus on posterior marginal probability density functions and covariances for the various model parameters. The covariance matrix obtained is very useful in providing insights into the trade-offs between the different variables and the uncertainties associated with them. We stay within the framework of perturbation theory, meaning that our emphasis is on the null-space of the linear inverse problem rather than the neglected non-linearity. The whole model space (including the nullspace) is sampled within reasonable parameter bounds, and hence the error bars are determined by all fitting models rather than subjective prior information. We estimated P and S models for spherical harmonic degree two only. The uncertainties are quite large and corresponding relative errors can exceed 100 per cent in the mid-mantle for Vp. We find a good correlation of our most likely S model with previous models but some small changes in amplitude. Our most likely P model differs quite strongly from the recent P model SB10L18 and the correlation between our most likely P and S models is small. Among all the good data-fitting models, there are, however, many that have a significant Vp −Vs correlation. We compute dlnVs/dlnVp from the models that correlate significantly.We find an increase with depth in the top 1500 km. Deeper in the mantle, normal-mode data prefer modest values compared with traveltime data.
Mechanical models to estimate the paleostress state from igneous intrusions
Authors: Stephens Tara , Walker Richard , Healy David , Bubeck Alodie , England Richard
Published: July 2018

Dikes and sills represent an important component of the deformation history in volcanic systems, but unlike dikes, sills are typically omitted from traditional paleostress analyses in tectonic studies. The emplacement of sheet intrusions is commonly associated with mode I fracturing in a low deviatoric stress state, where dilation is perpendicular to the fracture plane. Many natural examples of sills and dikes, however, are observed to accommodate minor shear offsets, in addition to a component of dilation. Here we present mechanical models for sills in the San Rafael Subvolcanic Field, Utah, which use field-derived measurements of intrusion attitude and opening angles to constrain the tectonic stress axes during emplacement, and the relative magma pressure for that stress state. The sills display bimodal dips to the NE and SW and consistent vertical opening directions, despite variable sill dips. Based on sill attitude and opening angles, we find that the sills were emplaced during a phase of NE-SW horizontal shortening. Calculated principal stress axes are consistent (within ~4°) with paleostress results for penecontemporaneous thrust faults in the area. The models presented here can be applied to any set of dilational structures, including dikes, sills, or hydrous veins, and represent a robust method for characterising the paleostress state in areas where other brittle deformation structures (e.g. faults), are not present.
A users guide to Neoproterozoic geochronology
Authors: Condon Daniel , Bowring Samuel
Published: July 2018

Geochronology is essential for understanding Neoproterozoic Earth history. Here we review the types of rocks and minerals that are used to date geologic events and the analytical protocols for the different radio-isotopic decay systems employed. We discuss the limitations and potential of these methodologies for dating Neoproterozoic stratigraphy, highlighting the major sources and magnitudes of uncertainties and the assumptions that often underpin them.
Towards machine ecoregionalization of Earth’s landmass using pattern segmentation method
Authors: Nowosad Jakub , Stepinski Tomasz
Published: July 2018

We present and evaluate a quantitative method for delineation of ecophysigraphic regions throughout the entire terrestrial landmass. The method uses the new pattern-based segmentation technique which attempts to emulate the qualitative, weight-of-evidence approach to a delineation of ecoregions in a computer code. An ecophysiographic region is characterized by homogeneous physiography defined by the cohesiveness of patterns of four variables: land cover, soils, landforms, and climatic patterns. It is expected that such a region is likely to be characterized by a single ecosystem. In this paper, we focus on the first-order approximation of the proposed method - delineation on the basis of the patterns of the land cover alone. We justify this approximation by the existence of significant spatial associations between various physiographic variables. Resulting ecophysiographic regionalization (ECOR) is shown to be more physiographically homogeneous than existing global ecoregionalizations (Terrestrial Ecoregions of the World (TEW) and Bailey’s Ecoregions of the Continents (BEC)). The presented quantitative method has an advantage of being transparent and objective. It can be verified, easily updated, modified and customized for specific applications. Each region in ECOR contains detailed, SQL-searchable information about physiographic patterns within it. It also has a computer-generated label. To give a sense of how ECOR compares to TEW and, in the U.S., to EPA Level III ecoregions, we contrast these different delineations using two specific sites as examples. We conclude that ECOR yields regionalization somewhat similar to EPA level III ecoregions, but for the entire world, and by automatic means.
Distribution of discontinuous mudstone beds within wave-dominated shallow-marine deposits: Star Point Sandstone and Blackhawk Formation, Eastern Utah, USA
Authors: Eide Christian , Howell John , Buckley Simon
Published: July 2018

Deposits of wave-dominated shorelines are typically considered to act as relatively simple hydrocarbon reservoirs and are commonly modeled as “tanks of sand”. However, important heterogeneities that can act as barriers to fluid flow occur at the parasequence, bedset and bed scales, especially in viscous oil or low permeability oil fields. Heterogeneities at the parasequence and bedset scale have been well-studied, but discontinuous mudstone-beds occurring within the shoreface have received little attention. The Book Cliffs and Wasatch Plateau are among the best exposed and most well-studied deposits of wave-dominated shallow-marine systems in the world. Two parasequences within these outcrops have been studied in detail to investigate the distributions of intrashoreface shales and to propose models for the controls on their distribution. A dataset consisting of 30 km of virtual outcrops derived from oblique helicopter-mounted lidar scanning with supporting stratigraphic sections makes it possible to collect a large quantity of accurate geometric data of depositional elements from inaccessible cliffs. A total of 921 discontinuous mudstone beds were measured. These occur as ellipses with long axes oriented normal to the paleoshoreline. Lengths and widths of these mudstone beds exhibit a lognormal distribution, with means of 21.9 and 13.8 m respectively. Within the shoreface succession, the number of mudstone beds increases downwards while size does not vary significantly with stratigraphic height. There is an average of 100 m cumulative length of shale per 100m of horizontal outcrop; this increases threefold near both wave-dominated deltas and bedset boundaries that reflect minor sea-level fluctuations during progradation.
Distributions of geohopanoids in peat: implications for the use of hopanoid-based proxies in natural archives
Authors: Inglis Gordon , Naafs B. , Zheng Yanhong , McClymont Erin , Evershed Richard , Pancost Richard
Published: July 2018

Hopanoids are pentacyclic triterpenoids produced by a wide range of bacteria. Within modern settings, hopanoids mostly occur in the biological 17β,21β(H) configuration. However, in some modern peatlands, the C31 hopane is present as the thermally-mature 17α,21β(H) stereoisomer. This has traditionally been ascribed to isomerisation at the C-17 position catalysed by the acidic environment. However, recent work has argued that temperature and/or hydrology also exert a control upon hopane isomerisation. Such findings complicate the application of geohopanoids as palaeoenvironmental proxies. However, due to the small number of peats that have been studied, as well as the lack of peatland diversity sampled, the environmental controls regulating geohopanoid isomerisation remain poorly constrained. Here, we undertake a global approach to investigate the occurrence, distribution and diagenesis of geohopanoids within peat, combining previously published and newly generated data (n = 395) from peatlands with a wide temperature (-1 to 27°C) and pH (3 to 8) range. Our results indicate that peats are characterised by a wide range of geohopanoids. However, the C31 hopane and C32 hopanoic acid (and occasionally the C32 hopanol) typically dominate. C32 hopanoic acids occur as αβ- and ββ-stereoisomers, with the ββ-isomer typically dominating. In contrast, C31 hopanes occur predominantly as the αβ-stereoisomer. These two observations collectively suggest that isomerisation is not inherited from an original biological precursor (i.e. biohopanoids). Using geohopanoid ββ/(αβ+ββ) indices, we demonstrate that the abundance of αβ-hopanoids is strongly influenced by the acidic environment, and we observe a significant positive correlation between C31 hopane isomerisation and pH (n = 94, r2 = 0.64, p < 0.001). Crucially, there is no correlation between C31 hopane isomerisation and temperature. We therefore conclude that within peats, αβ-hopanoids are acid-catalysed diagenetic products and their occurrence at shallow depths indicates that this isomerisation is rapid. This shows that geohopanoid ββ/(αβ+ββ) indices can be used to reconstruct pH within modern and ancient peat-forming environments. However, we only recommend using ββ/(αβ+ββ) indices to interrogate large amplitude (> 1 pH unit) and longer-term (> 1 kyr) variation. Overall, our findings demonstrate the potential of geohopanoids to provide unique new insights into understanding depositional environments and interpreting terrestrial organic matter sources in the geological record.
Enhancement of the accuracy of single epoch GPS positioning for long baselines by local ionospheric modelling
Authors: Assiadi Mohammed , Edwards Stuart , Clarke Peter
Published: July 2018

Single-epoch relative GPS positioning has many advantages, especially for monitoring dynamic targets .In this technique, errors occurring in previous epochs cannot affect the position accuracy at the current epoch, but careful processing is required, and resolving carrier phase ambiguities is essential. Statistical ambiguity resolution functions have been used to determine the best values of these ambiguities. The function inputs include as a minimum the known base station position, the approximate roving antenna ‘seed’ position, and the dual-frequency carrier phase measurements from both receivers. We investigate different solutions to find the ambiguity function inputs that achieve the highest ambiguity resolution success rate. First, we address the rover seed position. A regionally-filtered undifferenced pseudorange coordinate solution proves better than a double-differenced one. Multipath errors approximately repeat themselves every sidereal day in the case of static or quasi-static antennas; applying a sidereal filter to the pseudorange-derived positions mitigates their effects. Second, we address the relative carrier phase measurements, which for medium to long baselines are significantly affected by ionospheric propagation errors imperfectly removed during differencing. In addition to the IGS ionospheric model, we generate a local pseudorange-based ionospheric correction. Applying this correction improves the quality of the phase measurements, leading to more successful ambiguity resolution. Temporally smoothing the correction by means of a Kalman filter further improves the phase measurements. For baselines in the range 60-120 km, the mean absolute deviation of single-epoch coordinates improves to 10-20 cm, from 30-50 cm in the default case.
Kinematics of the active West Andean fold-and-thrust belt (Central Chile): structure and long-term shortening rate
Authors: Riesner Magali , Lacassin Robin , Simoes Martine , Armijo Rolando , Rauld Rodrigo , Vargas Gabriel
Published: July 2018

West-verging thrusts, synthetic with the Nazca - South America subduction interface, have been recently discovered at the western front of the Andes. At ~33°30’S, the active San Ramón fault stands as the most frontal of these west-verging structures, and represents a major earthquake threat for Santiago, capital city of Chile. Here we elaborate a detailed 3D structural map and a precise cross-section of the West Andean fold-and-thrust belt based on field observations, satellite imagery and previous structural data, together with digital topography. We then reconstruct the evolution of this frontal belt using a trishear kinematic approach. Our reconstruction implies westward propagation of deformation with a total shortening of 9-15 km accumulated over the last 25 Myr. An overall long-term shortening rate of 0.1-0.5 mm/yr is deduced. The maximum value of this shortening rate compares well with the rate that may be inferred from recent trench data across the San Ramón fault and the slip associated with the two past Mw>7 earthquakes. This suggests that the San Ramón fault is most probably the only presently active fault of the West Andean fold-and-thrust-belt and that most - if not all - the deformation is to be released seismically.
Global assessment and mapping of changes in mesoscale landscapes: 1992–2015
Authors: Nowosad Jakub , Stepinski Tomasz , Netzel Pawel
Published: July 2018

Monitoring global land cover changes is important because of concerns about their impact on environment and climate.The release by the European Space Agency (ESA) of a set of worldwide annual land cover maps covering the 1992–2015 period makes possible a quantitative assessment of land change on the global scale.While ESA land cover mapping effort was motivated by the need to better characterize global and regional carbon cycles, the dataset may benefit a broad range of disciplines.To facilitate utilization of ESA maps for broad-scale problems in landscape ecology and environmental studies, we have constructed a GIS-based vector database of mesoscale landscapes – patterns of land cover categories in 9km × 9km tracts of land. First, we reprojected ESA maps to the Fuller projection to assure that each landscape in the database has approximately the same size and shape so the patterns of landscapes at different locations can be compared. Second, we calculated landscape attributes including its compositions in 1992 and 2015, magnitude of pattern change, categories transition matrix for detailed characterization of change, fractional abundances of plant functional types (PFTs) in 1992 and 2015, and change trend type – a simple, overall descriptor of the character of landscape change.Combining change trends and change magnitude information we constructed a global, thematic map of land change; this map offers a visualization of what, where, and to what degree has changed between 1992 and 2015.The database is SQL searchable and supports all GIS vector operations. Using change magnitude attribute we calculated that only 22% of total landmass experienced significant landscape change during the 1992-2015 period, but that change zone accounted for 80% of all pixel-based transitions.Dominant land cover transitions were forest → agriculture followed by agriculture → forest. Using PFTs attributes to calculate global aggregation of gross and net changes for major PFTs yielded results in agreement with other recent estimates.
Lake sediment records of persistent organic pollutants and polycyclic aromatic hydrocarbons in Southern Siberia mirror the changing fortunes of the Russian economy over the past 70 years
Authors: Adams Jennifer , Martins César , Rose Neil , Shchetnikov Alexander , Mackay Anson
Published: July 2018

Persistent organic pollutants (POPs) and polycyclic aromatic hydrocarbons (PAHs) have previously been detected in the surface sediments, water, and endemic organisms of Lake Baikal, a UNESCO World Heritage Site. The Selenga River is the primary source of freshwater to Lake Baikal, and transports pollutants accumulating in the Selenga River basin to the lake. Sources of POPs and PAHs in the Selenga River basin grew through the 20th century. In the present study, temporal changes in the concentrations of PAHs and POPs were reconstructed from two lakes in the Selenga River basin over the past 150 years using paleolimnological techniques. Increased concentrations in PAHs and PCBs were recorded initially in the 1930s. The 1940s to 1980s was the period of greatest exposure to organic contamination, and concentrations of dichlorodiphenyltrichloroethane (DDT), polychlorinated biphenyls (PCBs), hexachlorocyclohexanes (HCHs) and many PAHs peaked between the 1960s and 1980s in the two lakes. Declines in concentrations and fluxes were recorded for most PAHs and POPs in the 1980s and 1990s. Temporal trends in concentrations of total and individual compounds/congeners of PAH, PCBs, and polybrominated diphenyl ethers (PBDEs) indicate the contribution of both local and regional sources of contamination in the 20th and 21st centuries. Temporal variations in contaminants can be linked to economic and industrial growth in the former USSR after World War II and the economic decline of Russia in the late-1980s and early-1990s, as well as global trends in industrialization and development during the mid-20th century.
Pre-Alpine contrasting tectono-metamorphic evolutions within the Southern Steep Belt, Central Alps
Authors: Roda Manuel , Zucali Michele , Li Zheng-Xiang , Spalla Maria , Yao Weihua
Published: July 2018

In the Southern Steep Belt, Italian Central Alps, relicts of the pre-Alpine continental crust are preserved. Between Valtellina and Val Camonica, a poly-metamorphic rock association occurs, which belongs to the Austroalpine units and includes two classically subdivided units: the Languard-Campo nappe (LCN) and the Tonale Series (TS). The outcropping rocks are low to medium grade muscovite, biotite and minor staurolite-bearing gneisses and micaschists, which include interlayered garnet- and biotite-bearing amphibolites, marbles, quartzites and pegmatites, as well as sillimanite-bearing gneisses and micaschists. Permian intrusives (granitoids, diorites and minor gabbros) emplaced in the metamorphic rocks. We performed a detailed structural, petrological and geochronological analysis focusing on the two main lithotypes, namely, staurolite-bearing micaschists and sillimanite- bearing paragneisses, to reconstruct the Variscan and Permian-Triassic history of this crustal section. The reconstruction of the tectono-metamorphic evolution allows for the distinction between two different tectono-metamorphic units during the early pre-Alpine evolution (D1) and predates the Permian intrusives, which comprise rocks from both TS and LCN. In the staurolite- bearing micaschists, D1 developed under amphibolite facies conditions (P=0.7- 1.1 GPa, T=580-660◦C), while in the sillimanite-bearing paragneisses formed under granulite facies conditions (P=0.6-1.0 GPa, T>780◦C). The two tectono-metamorphic units coupled together during the second pre-Alpine stage (D2) under granulite-amphibolite facies conditions at a lower pressure (P=0.4-0.6 GPa, T=620-750◦C) forming a single tectono-metamorphic unit (Languard- Tonale Tectono-Metamorphic Unit), which comprised the previously distinguished LCN and TS. Geochronological analyses on zircon rims indicate ages ranging between 250 and 275 Ma for D2, contemporaneous with the emplacement of Permian intrusives. This event developed under a high thermal state, which is compatible with an extensional tectonic setting that occurred during the exhumation of the Languard-Tonale Tectono-Metamorphic Unit. The extensional regime is interpreted as being responsible for the thinning of the Adriatic continental lithosphere during the Permian, which may be related to an early rifting phase of Pangea.
A fossiliferous spherule-rich bed at the Cretaceous-Paleogene (K-Pg) boundary in Mississippi, USA: implications for the K-Pg mass extinction event in the MS Embayment and Eastern Gulf Coastal Plain
Authors: Witts James , Landman Neil , Garb Matthew , Boas Caitlin , Larina Ekaterina , Rovelli Remy , Edwards Lucy , Sherrell Robert , Cochran J.
Published: July 2018

We describe an outcrop of the Cretaceous–Paleogene (K–Pg) boundary exposed due to construction near New Albany, Union County, Mississippi. It consists of the Owl Creek Formation and overlying Clayton Formation. The Owl Creek Formation is rich in the ammonites Discoscaphites iris and Eubaculites carinatus, which, along with biostratigraphically important dinoflagellate cysts and calcareous nannofossils, indicate deposition occurred within the last 1 million years, most likely last 500 kyrs, of the Cretaceous. The base of the overlying Clayton Formation marks the K–Pg boundary, and consists of a 15-30 cm thick muddy, poorly sorted quartz sand containing abundant spherules representing ejecta derived from the Chicxulub impact event. Impact spherules range in size from 0.5 mm to 1 mm in diameter and are hollow and well preserved, with details such as smaller vesicular spherules enclosed within. The spherules are altered to clay minerals such as smectite and are typical of those found at K–Pg boundary sites in the Gulf of Mexico and beyond. Spherules are scattered throughout the bed, and surface counts suggest an average of 4 spherules per cm2. Macrofossils within the spherule bed represent a rich fauna of ammonites, benthic molluscs (bivalves and gastropods), echinoids, as well as crabs and sharks. Macrofossil preservation ranges from whole to fragmentary, with most fossils preserved as internal moulds. The infill of the fossils is lithologically identical to the matrix of the spherule bed, including impact ejecta preserved within phragmocones and body chambers of ammonites, and differs from the underlying Owl Creek Formation. This suggests that the animals were either alive or loosely scattered on the sea floor at the time of deposition. Grain size changes indicate multiple events were responsible for deposition, and together with taphonomic evidence are consistent with dynamic high energy post-impact processes. Later sea level change during the Paleocene is responsible for a sharp contact at the top of the spherule bed. Geochemical evidence from the Owl Creek and Clayton Formations at this locality indicate numerous local paleoenvironmental changes affected the Mississippi Embayment at the time of the K–Pg boundary and mass extinction event.
Robust Normal Mode Constraints on Inner-Core Anisotropy from Model Space Search
Authors: Beghein Caroline , Trampert Jeannot
Published: July 2018

A technique for searching full model space that was applied to measurements of anomalously split normal modes showed a robust pattern of P-wave and S-wave anisotropy in the inner core. The parameter describing P-wave anisotropy changes sign around a radius of 400 kilometers, whereas S-wave anisotropy is small in the upper two-thirds of the inner core and becomes negative at greater depths. Our results agree with observed travel-time anomalies of rays traveling at epicentral distances varying from 150° to 180°. The models may be explained by progressively tilted hexagonal close-packed iron in the upper half of the inner core and could suggest a different iron phase in the center.
Perancangan Sistem InformasiPenelusuran Data Alumni Berbasis Web
Authors: Sutedi Sutedi
Published: July 2018

Alumni’s success in getting jobs that are suitable with their competence and with appropriateincome soon after graduation is an indicator of success of a study program. Therefore, it isnecessary to develop a system that can help track the alumni data easily. The development of theinformation system of web-based alumni data tracking can be an alternative solution taking intoconsideration that the alumni can report the development of their career wherever and wheneverthey would like to. However, for the purpose of the completeness of the alumni data, it isnecessary to develop a variety of attributes to track alumni data more completely
Computer Algebra and Material Design
Authors: Kikuchi Akihito
Published: July 2018

This article is intended to an introductory lecture in material physics, in which themodern computational group theory and the electronic structure calculation are in collaboration. The effort of mathematicians in field of the group theory, have ripened as a new trend, called “computer algebra”, outcomes of which now can be available as handy computational packages, and would also be useful to physicists with practical purposes. This article, in the former part, explains how to use the computer algebra for the applications in the solid-state simulation, by means of one of the computer algebra package, the GAP system. The computer algebra enables us to obtain various group theoretical properties with ease, such as the representations, the character tables, the subgroups, etc. Furthermore it would grant us a new perspective of material design, which could be executed in mathematically rigorous and systematic way. Some technical details and some computations which require the knowledge of a little higher mathematics (but computable easily by the computer algebra) are also given. The selected topics will provide the reader with some insights toward the dominating role of the symmetry in crystal, or, the “mathematical first principles” in it. In the latter part of the article, we analyze the relation between the structural symmetry and the electronic structure in C60 (as an example to the sysmem without periodicity). The principal object of the study is to illustrate the hierarchical change of the quantum-physical properties of the molecule, in accordance with the reduction of the symmetry (as it descends down in the ladder of subgroups). As an application, this article also presents the computation of the vibrational modes of the C60 by means of the computer algebra. In order to serve the common interest of the researchers, the details of the computations (the required initial data and the small programs developed for the purpose)are explained as minutely as possible.
Algorithmic Manifold and Application to P versus NP Problem
Authors: Yabu Takuya
Published: July 2018

About P versus NP problem, it has been studied for long time. Recent literature has shown that the existing proof method using the diagonal argument or the circuit complexity is not effective. On the other hand, as another approach, calculation of time complexity based on the geometric method is also performed, but it is limited to the quantum algorithm, and it is an application example to the existing method of lower band derivation of quantum circuit complexity, it is essentially unchanged.　In this paper, I introduce algorithmic manifolds that explain algorithms by geometric method and show that they are topologically homogeneous with respect to P versus NP problem. And I will also discuss polynomial-time reduction method of NP problem for class P.
Application of a Rectified Linear Unit (ReLU) Based Artificial Neural Network to Cetane Number Predictions
Authors: Kessler Travis , Dorian Gregory , Mack John Hunter
Published: July 2018

Due to the high cost and time required to synthesize alternative fuel candidates for comprehensive testing, an Artificial Neural Network (ANN) can be used to predict fuel properties, allowing researchers to preemptively screen desirable fuel candidates. However, the accuracy of an ANN is limited by its error, measured by the root mean square error (RMSE), standard deviation, and r-squared values derived from a given input database. The present work improves upon an existing model for predicting the Cetane Number (CN) by changing the neuron activation function of the ANN from sigmoid to rectified linear unit (ReLU). This change to the ANN’s architecture provides an increase in accuracy by reducing the RMSE by 21.4% (1.35 CN units), the average standard deviation across models by 28%, and increasing the r-squared value by 0.0492 across a wide range of molecular structures. Additionally, by using the ReLU activation function, input data is not required to be normalized, which reduces the likelihood of an inaccurate prediction on future fuel candidates which may have input parameters outside the range of normalization. Increasing the accuracy of the predictive ANN in this way will allow researchers to obtain more accurate fuel property predictions for promising fuel candidates.
Oscar
Authors: Anderson Jessica
Published: July 2018

Our idea is an invention that keeps a plant watered for people who are forgetful, who are away from home a lot, or for plants that require specific amounts of water.
Blast actions from high explosives. Studies on their simulation and effects
Authors: Masi Filippo
Published: July 2018

Bombing attacks are one of the most destructive means of the terrorist threat in terms of both human lifes and cultural heritage. The mechanical problem of the effects of a blast on structures, in order to assess their vulnerability and design functioning protections for saving human lifes and preserving historical monuments, is a crucial issue for the present international situation. Here, we introduce a strategy suited for the calculation of the blast actions on structures comparing three different numerical schemes: JWL, CONWEP and TM5-1300. A procedure based upon precise interpolations of the experimental data allows comparison of the above models on simple cases.We simulate first a blast inside Pantheon in Rome, taking into account for the complex pattern of multiple reflected blast waves and the nonlinearities of no-tension materials. Then, we consider the response to an explosion inside a fuselage made of aluminium alloys. In this last case we discuss the opportunity given by cost-effective numerical approaches in designing protections through the development of a new concept of a passive protectivedevice for aircrafts cabins.
Opportunities to Improve Academic Research Through Open Research Practices
Authors: Berg Devin R.
Published: July 2018

An abstract submitted to accompany a presentation at the 2018 Polytechnic Summit, June 4--6, in Lima, Peru.
Rolling with the Punches: An Examination of Team Performance in a Design Task Subject to Drastic Changes
Authors: McComb Christopher , Cagan Jonathan , Kotovsky Kenneth
Published: July 2018

Designers must often create solutions to problems that exhibit dynamic characteristics. For instance, a client might modify specifications after design has commenced, or a competitor may introduce a new technology or feature. This paper presents a cognitive study that was conducted to explore the manner in which design teams respond to such situations. In the study, teams of undergraduate engineering students sought to solve a design task that was subject to two large, unexpected changes in problem formulation that were introduced during solving. High- and low-performing teams demonstrated very different approaches to solving the problem and overcoming the changes. The results indicate that there may exist a relationship between problem characteristics and fruitful solution strategies.