Miracle-dz/UniFAR-FTUs huggingface dataset:
Factors influencing the deposit geometry of experimental turbidity currents: implications for sand-body architecture in confined basins

Abstract Two sets of scaled laboratory experiments were performed to examine the effect of flow volume, flow density and grain-size distribution on the transport efficiency of turbidity currents. The experiments employed two sediment analogues (ballotini and silica flour) intended to model medium- to coarse-grained sand and mud respectively. In the first set of experiments each parameter was varied to examine its effect upon deposit geometry. Increases in the initial flow density, volume and proportion of fines had the effect of increasing the amount of sediment that was transferred to the floor of the experimental tank by the turbidity currents. Increase of each of these parameters has a characteristic effect on the three-dimensional geometry of the deposit: the deposits of large-volume flows are elongate, and those of fines-rich flows are broad. Increase of flow density increases the initial potential energy of the flow, thus increasing the runout distance; increase of the initial density beyond a sediment concentration of 13% by mass results, however, in a reverse of the geometrical trend of deposit elongation, possibly because of turbulence suppression at high densities. Increase of flow volume also increases the initial potential energy, and reduces the rate of velocity decrease due to gravitational spreading. Increase in the proportion of fines leads to maintenance of negative buoyancy, as the fine fraction remains suspended until the flow has virtually come to rest; it also decreases the settling velocity of the coarser fraction and thus delays its sedimentation. The second set of experiments was performed to investigate the influence of flow efficiency on the interaction of turbidity currents with topography. A single arcuate obstacle was placed in the path of the flows. In successive experiments flow efficiency was increased by progressively increasing the proportion of fines (silica flour). Both the proportion of sediment reaching the obstructing topography and the proportion of it able to surmount the topography increased as flow efficiency increased. Thus flow efficiency may determine whether or not an enclosed basin hosts deposits whose geometry has been affected by the confinement, and may also determine the relative effectiveness of the topography in confining inbound turbidity currents, and thus trapping their sediment load.
THE EFFECTS OF MIND MAPPING AT WHILE-READING STAGE ON EFL STUDENTS’ READING COMPREHENSION AT A LOCAL HIGH SCHOOL IN KIEN GIANG PROVINCE, VIETNAM

There is an increased attention to research into the use of mind mapping as a useful tool for enhancing students’ reading comprehension. However, few studies have been conducted to examine the effects of mind mapping at the reading stage on students’ reading comprehension within the Vietnamese context. This paper therefore investigates the effects of mind mapping on 11th graders’ reading comprehension and their attitudes towards this strategy. Participants in this study include 60 students at a local school in Kien Giang province. The data discussed in this paper include tests and interviews. The findings reveal that using mind mapping in the teaching process of reading texts had a moderate impact. Pedagogical implications for teachers and school administrators are presented. <p> </p><p><strong> Article visualizations:</strong></p><p><img src="/-counters-/soc/0019/a.php" alt="Hit counter" /></p>
Effect of aerosol on trade cumulus cloud morphology

[1] Large-eddy simulations of trade wind cumulus clouds are conducted for clean and polluted aerosol conditions and at a number of different grid sizes to explore (1) the microphysical and morphological responses of fields of cumulus to aerosol perturbations and (2) the robustness of these responses to resolution. Cloud size distributions are shown to be well approximated by a negative power law function indicating that as resolution increases, more and more small clouds are resolved. Cloud fraction in the highest-resolution simulations is 30% higher than in the coarse-resolution simulations. Polluted cloud populations contain higher numbers of smaller clouds than clean cloud populations. Their frequency of convection is higher and lifetimes are shorter. The polluted clouds also tend to have higher cloud-averaged liquid water contents. It is hypothesized that these responses are a result of a chain reaction set off by stronger evaporation at cloud edges in the case of polluted clouds. In all cases, the smallest clouds either dominate or contribute significantly to cloud fraction and cloud reflectance, in accord with recent satellite studies. The response of cloud fraction and liquid water path to aerosol changes is shown to be strongly dependent on the definition of what constitutes a “cloud,” suggesting that caution be exercised before parameterizing these responses.
The Baltic Ice Lake in the southwestern Baltic: sequence‐, chrono‐ and biostratigraphy

Jensen, J. B. , Bennike, O. , Witkowski, A. , Lemke, W. & Kuijpers, A. 1997 (September): The Baltic Ice Lake in the southwestern Baltic: sequence‐, chrono‐ and biostratigraphy. Boreas, Vol. 26, pp. 217–236. Oslo. ISSN 0300–9483.
The scaling of fracture compliance

Abstract The seismic visibility of fractures depends on the magnitude of their normal and shear compliance and how these quantities vary with the scale of the fracture and depth of burial. Reliable estimates of fracture compliance as a function of confining pressure, in the range 10-13–10-14 m Pa-1, have been obtained from laboratory measurements on core samples. The possibility of fractal scaling of fracture parameters has been proposed, in which case fracture compliance might be expected to increase with the scale of the fracture. Laboratory and field estimates of fracture compliance are presented covering a range of fracture sizes. Compliance is shown to increase with the scale of the fractures. Results obtained are broadly consistent with the magnitudes predicted from linear slip theory, in which the displacement discontinuity across a partially sealed interface is linearly related to the traction on the interface.
Debris flow rheology: Experimental analysis of fine‐grained slurries

The rheology of slurries consisting of ≤2-mm sediment from a natural debris flow deposit was measured using a wide-gap concentric-cylinder viscometer. The influence of sediment concentration and size and distribution of grains on the bulk rheological behavior of the slurries was evaluated at concentrations ranging from 0.44 to 0.66. The slurries exhibit diverse rheological behavior. At shear rates above 5 s−1 the behavior approaches that of a Bingham material; below 5 s−1, sand exerts more influence and slurry behavior deviates from the Bingham idealization. Sand grain interactions dominate the mechanical behavior when sand concentration exceeds 0.2; transient fluctuations in measured torque, time-dependent decay of torque, and hysteresis effects are observed. Grain rubbing, interlocking, and collision cause changes in packing density, particle distribution, grain orientation, and formation and destruction of grain clusters, which may explain the observed behavior. Yield strength and plastic viscosity exhibit order-of-magnitude variation when sediment concentration changes as little as 2–4%. Owing to these complexities, it is unlikely that debris flows can be characterized by a single rheological model.
On the relationship between thin Birkeland current arcs and reversed flow channels in the winter cusp/cleft ionosphere

[1] In this paper we study reversed flow events (RFEs) that seem regulated by Birkeland current arcs in the winter cusp ionosphere above Svalbard. An RFE is a longitudinally elongated, 100–200 km wide channel, in which the flow direction is opposite to the background convection, persisting for 10–20 min. The RFE onset occurs with the brightening of a discrete arc near the open-closed boundary. The auroral arc is situated exactly at a sharp clockwise flow reversal, consistent with a converging electric field and an upward field-aligned current. One category of RFEs propagates into the polar cap in tandem with poleward moving auroral forms, while another category of RFEs moves with the cusp/cleft boundary. The RFE phenomenon is addressed to a region void of electron precipitation, and in lack of direct sunlight the E-region conductivity will be very low. We propose two possible explanations: (1) the RFE channel may be a region where two MI current loops, forced by independent voltage generators, couple through a poorly conducting ionosphere and (2) the reversed flow channel may be the ionospheric footprint of an inverted V-type coupling region. Electron beams of <1 keV will not give rise to significant conductivity gradients, and the form of a discontinuity in the magnetospheric electric field will be conserved when mapped down to the ionosphere, although reduced in amplitude. These two explanations may be related in the sense that the boundary discontinuity in the magnetospheric electric field in (1) may be the driver for the inverted V in (2).
Foreshocks of shallow New Zealand earthquakes

Abstract A foreshock is defined as an earthquake occurring within 30 days before, and within 50 km of, a main shock. This is based on a 4-fold increase in the average rate of activity in this interval, which is too small an increase to be of itself useful for prediction purposes. This foreshock activity is not confined to the area defined by the subsequent aftershocks. Many, but probably not all, earthquakes of ML⩾6 in New Zealand have foreshocks. The largest fore shock is often about 2 magnitude units smaller than the main shock. There is no readily discernible pattern in the spatial distribution of main shocks with and without foreshocks.
A NEW TURTLE FROM THE ARUNDEL CLAY FACIES (POTOMAC FORMATION, EARLY CRETACEOUS) OF MARYLAND, U.S.A.

Abstract A new paracryptodiran turtle, Arundelemys dardeni, gen. et sp. nov., is described on the basis of an isolated, nearly complete skull from the Early Cretaceous Arundel Clay facies of Maryland, USA. The basicranial region exhibits the paracryptodiran condition of a single foramen for the canalis caroticus internus located midway along the basisphenoid. As revealed by CT scans, the basicranial region of Arundelemys is unusual in that the right and left canales carotici interni merge just before reaching the sella turcica and the canalis caroticus lateralis is very small or absent. A phylogenetic analysis places Arundelemys dardeni as the basal-most member of the Paracryptodira. Within the Paracryptodira, Arundelemys dardeni is most similar to Compsemys victa in general proportions.
The use of dispersible clays to reduce water repellency of sandy soils

Water-repellency in sandy soils is determined by the amount of hydrophobic organic matter coating the sand particles and the specific surface area of the sands. The hydrophobic state can be simulated by coating hydrophilic sand with cetyl alcohol. Admixture of finely particulate materials with either naturally occurring water-repellent sands or the model cetyl alcohol-coated sand markedly reduced the water-repellency. Dispersible sodic clays were more effective than calcium saturated clays in reducing water-repellency, suggesting that the addition of dispersible, fine-grained illites and kaolinites couid play an important role in the rapid control of water-repellent soils in field situations.
A transmission electron microscope study of exsolution and coarsening in iron‐bearing clinopyroxene from synthetic analogues of chondrules

Abstract— The microstructure of Fe‐rich clinopyroxene from synthetic analogues of chondrules was studied by transmission electron microscopy. The samples were cooled at various rates from 1455 °C to the quench temperature of 1000 °C. Slow cooling at rates below approximately 50–60 °C/h leads to the development of coherent pigeonite/augite exsolution lamallae on (001). A final wavelength of 19.6 ± 1.1 nm was obtained at a cooling rate of 10 °C/h, and 17.4 ± 2.4 ran at a cooling rate of 50 °C/h. Faster cooling at rates between approximately 50 and 450 °C/h yields only modulated structures with a wavelength on the order of 17–19 nm for the (001) orientation.
The magnetic field of the equatorial magnetotail: AMPTE/CCE observations at R < 8.8 RE

The Active Magnetospheric Particle Tracer Explorers/Charge Composition Explorer (AMPTE/CCE) magnetic field experiment has provided extensive measurements of the vector field near the equatorial plane in the inner magnetotail. Taillike distortions from the dipole field direction may reach 80° near the AMPTE/CCE apogee of 8.8 RE. The Bz (north-south) field component in dipole coordinates was always positive within 0.5 RE of the equatorial current sheet, indicating that neutral lines were never seen inside of 8.8 RE. South of −0.5 RE, Bz values are sometimes southward due to extremely taillike fields and the southward tilt of the tail in dipole coordinates during northern hemisphere winter. Fields are most taillike near midnight and during times of high Kp. At 8.5 RE the equatorial field magnitude depressions are roughly half the dipole field strength of 51 nT. These depressions are larger at lesser distances reaching −40 nT at 3.4 RE for Kp ≤ 2- and −80 nT for Kp ≥ 3+. The equatorial crossing points of midnight field lines are computed using the observed field depressions. Mapping auroral boundaries along these distorted field lines indicates that most auroral arcs map to magnetospheric locations beyond 12 RE, but that low latitude arcs may well occur on closed field lines earthward of this distance. Evidence is found confirming that a cross-tail field component in the inner magnetotail is related to the interplanetary sector structure but, contrary to earlier results, the effect is found to be larger during geomagnetically disturbed times.
Spectral solar UV irradiance data for cycle 21

The Nimbus 7 Solar Backscatter Ultraviolet (SBUV) instrument, which began taking data in November 1978, was the first instrument to make solar UV irradiance measurements covering both the minimum and maximum activity levels of a solar cycle. The currently archived irradiance data set was processed with an instrument characterization which fails to completely account for sensor degradation in the later part of the data record, thus limiting the accuracy of estimated long-term solar activity variations and the scientific value of the data. In this paper, we describe an improved Nimbus 7 SBUV spectral irradiance data set, which utilizes a more accurate model for instrument sensitivity and treats other time-dependent problems in the archived data. Estimated long-term irradiance changes during solar cycle 21 are 8.3(±2.6)% at 205 nm, and 4.9(±1.8)% at 240 nm. The revised Nimbus 7 SBUV irradiance data are in good agreement with predictions of solar cycle variations from the Mg II index proxy model. These solar irradiance changes are also consistent with overlapping irradiance data from the declining phase of solar cycle 21 measured by the Solar Mesosphere Explorer (SME). The Nimbus 7 SBUV irradiance data represent the earliest component of a 20+ year continuous record of solar spectral UV activity.
A numeric method for estimating infiltration, redistribution, drainage, and evaporation of water from soil

A general numeric method is described for estimating one-dimensional infiltration, redistribution, evaporation, and drainage of water from soil. The type of flow is determined by the water flux at the surface of soil or the bottom boundary. The method provides for hysteresis in the water content-pressure head relation. Comparison with measurement made on soil columns for infiltration, redistribution, and evaporation were made. Good agreement was obtained between measured and computed values.
Intra‐seasonal oscillations observed in the MLT region above UK (52°N, 2°W) and ESRANGE (68°N, 21°E)

Analyses of intra‐seasonal oscillations (i.e., oscillations with periods of ∼30–100 days) in the MLT region made by meteor radars at middle (UK, five years of data) and high latitudes (Esrange, three years of data) are presented in this work. There is clear evidence of ∼75‐day variability in the mean winds. This intra‐seasonal oscillation appears to be a prominent feature of the mean zonal circulation and was observed quite regularly in the time intervals December 1996–September 2001 over UK and October 1999–December 2002 over Esrange. The intra‐seasonal oscillations observed over Esrange are coherent in both amplitude and phase over the height range of ∼80–100 km covered by the radar. They are especially strong in the range 90–97 km, weaker near 87–88 km and stronger again near 81 km. At these lower heights the intra‐seasonal oscillations are usually of longer period (∼80 days) than, and are out of phase with, the oscillations at the upper heights. We also note that this oscillation is a common feature in the meridional winds over the UK. It is present, but intermittent, in the meridional winds over Esrange.
Shear fracture patterns and connectivity at geometric complexities along strike‐slip faults

Shear fracture patterns and connectivity at geometric complexities such as echelon fault steps and fault bends along strike-slip faults are investigated by simulating shear fracture propagation paths using a displacement discontinuity boundary element method together with a maximum distortional strain energy density criterion. It is shown that shear fracture patterns and connectivity depend on the specific geometric configurations, the applied stress orientations and the coefficient of friction. For a given initial configuration of the major faults, the subsequent patterns of the associated shear fractures and their linkage can be predicted if the remote state of stress and the coefficient of friction are known. The analyses of fault geometries commonly encountered in nature have important implications for evaluating the effect of faults on fluid flow and earthquake hazards associated with the geometric complexities along strike-slip faults in the upper crust.
Evaluation of Multidate ERS-1 and Multispectral Landsat Imagery for Wetland Detection in Southern Ontario

RESUMECet article evalue l'utilisation d'images radar a synthese d'ouverture multidates (RSO) acquises par le satellite ERS-1 et des images multispectrales du capteur Landsat Thematic Mapper (TM) pour la detection et la classification des zones humides dans le sud de l'Ontario. L'etude demontre que quoique les images mono-canal ERS-1 donnent des resultats faibles, les performances des donnees multidates ERS-1 sont comparables a celles des donnees Landsat. La meilleure combinaison d'images ERS-1 acquises au cours d'une periode de quatre mois permet d'atteindre des resultats satisfaisants avec une precision de 83% globalement pour la zone d'etude. Une analyse plus detaillee a permis de demontrer que la performance des donnees radar multidates est nettement meilleure que les donnees radar unidates pour le suivi des zones humides. Comme les donnees radar ne sont pas affectees par la presence de nuages, ces donnees constituent une alternative potentielle aux donnees satellite optiques.
Landslide hazard assessment of the 2008 Wenchuan earthquake: a case study in Beichuan area

The Wenchuan earthquake (magnitude Ms = 8.0) of 12 May 2008 triggered widespread and large-scale landslides over an area of about 50 000 km2. A study was undertaken to determine the primary factors associated with seismic landslide occurrence. An index-based approach used to assess earthquake-triggered landslide hazard in the central part of the Wenchuan earthquake area affected is described. Slope gradient, relief amplitude, lithology, bedding–slope relations, fault proximity, stream proximity, and antecedent rainfall are recognized as factors that may have had an important influence on landslide occurrence. The assessment of the influence of each of these factors is presented through use of a series of maps showing areas of low, moderate, high, and very high landslide hazard. Areas identified as having “very high and high landslide hazard” were located along the earthquake-source fault and along both banks of the Jian River. The role of rainfall is very significant for future landslide occurrence in the.
Sr and Nd isotopes in river sediments from the Ganga Basin: Sediment provenance and spatial variability in physical erosion

[1] Sr and Nd concentrations and isotope compositions in sediment of the Ganga River, from Gangotri to Rajmahal, and its tributaries have been measured to determine provenance and the spatial variability in physical erosion among the Ganga subbasins. Sr and Nd in silicates range from 37 to 138 and from 10 to 36 μg/g, with 87Sr/86Sr and ɛNd of 0.7474–0.8428 and −25.5 to −15.5, respectively. The results suggest that >65% of Ganga mainstream sediments are derived from the Higher Himalayan Crystallines highlighting intense physical erosion in this region. The 87Sr/86Sr values of sediments in the Gangetic plain show nearly identical trends during two seasons, with a sharp and significant decrease at Barauni downstream of Gandak confluence. This brings out the major impact of the sediment contribution from the Gandak to the Ganga mainstream. Model calculation suggests that about half of the Ganga sediment at Rajmahal is sourced from the Gandak. The erosion rates in the Himalayan subbasins of the Ganga range between 0.5 and 6 mm/a (where a is years), with the Gandak having the highest erosion rate. High relief and intense precipitation over the headwater basins of the Gandak appear to drive the rapid and focused erosion of this basin. The results of this study and those in literature suggest that the eastern syntaxis (Brahmaputra), the western syntaxis (Indus), and the Gandak have much higher physical erosion rates than the other Himalayan basins. Focused erosion in the hot spots of these river basins contributes significantly to the global riverine sediment budget and influence regional tectonics.
Constraints on the depth of magnetized crust on Mars from impact craters

Large (diameter greater than ∼500 km) Martian impact basins are associated with observed magnetic fields which are statistically distinct from, and smaller than, fields associated with smaller craters. We suggest that this effect arises because impacts cause shock, heating, and excavation, reducing the magnetization of previously magnetized crust. For a simple, uniformly magnetized model the magnetic field at 100 km altitude is reduced by ∼50% when a crater-shaped demagnetization zone reaches the base of the magnetized layer. By analogy with terrestrial data, we assume that in Martian craters the zone of demagnetization extends to a depth of 0.04–0.15 crater diameters. On the basis of this assumption, the data suggest that the depth to the base of the magnetized layer on Mars, if uniform, is ∼35 km, with lower and upper bounds of 10 and 100 km, respectively. These bounds imply magnetizations of 5–40 A m−1 and are consistent with likely Mars geotherms at 4 Gyr B.P.
Destriping multisensor imagery with moment matching

Image destriping is necessary due to sensor-to-sensor variation within instruments. This has most often been done by assuming that each sensor views a statistically similar subimage, and a histogram of each sensor's response is made to match the overall histogram. Histogram matching shows sensitivity to violations of the similarity assumption. An alternative algorithm is suggested which matches the gain and offset of each sensor to typical values, and which is resistant to the effects of outliers. Tests on a sample image show the moment matching algorithm reduces the variance between sensors to a greater degree than histogram matching.