Miracle-dz/UniFAR-FTUs huggingface dataset:
The West African Monsoon Onset: A Concise Comparison of Definitions

AbstractThe onset of the West African monsoon (WAM) marks a vital time for local and regional stakeholders. While the seasonal progression of monsoon winds and the related migration of precipitation from the Guinea Coast toward the Sudan/Sahel is apparent, there exist contrasting man-made definitions of what the WAM onset means. Broadly speaking, onset can be analyzed regionally, locally, or over a designated intermediate scale. There are at least 18 distinct definitions of the WAM onset in publication, with little work done on comparing observed onset from different definitions or comparing onset realizations across different datasets and resolutions. Here, nine definitions have been calculated using multiple datasets of different metrics at different resolutions. It is found that mean regional onset dates are consistent across multiple datasets and different definitions. There is low interannual variability in regional onset, suggesting that regional seasonal forecasting of the onset provides few benefi.
Syngenetic sand veins and anti‐syngenetic sand wedges, Tuktoyaktuk Coastlands, western Arctic Canada

Sand‐sheet deposits of full‐glacial age in the Tuktoyaktuk Coastlands, western Arctic Canada, contain syngenetic sand veins 1–21 cm wide and sometimes exceeding 9 m in height. Their tall and narrow, chimney‐like morphology differs from that of known syngenetic ice wedges and indicates an unusually close balance between the rate of sand‐sheet aggradation and the frequency of thermal‐contraction cracking. The sand sheets also contain rejuvenated (syngenetic) sand wedges that have grown upward from an erosion surface. By contrast, sand sheets of postglacial age contain few or sometimes no intraformational sand veins and wedges, suggesting that the climatic conditions were unfavourable for thermal‐contraction cracking. Beneath a postglacial sand sheet near Johnson Bay, sand wedges with unusually wide tops (≤3.9 m) extend down from a prominent erosion surface. The wedges grew vertically downward during deflation of the ground surface, and represent anti‐syngenetic wedges. The distribution of sand veins and wedges within the sand sheets indicates that the existence of continuous permafrost during sand‐sheet aggradation can be inferred confidently only during full‐glacial conditions. Copyright © 2007 John Wiley & Sons, Ltd.
Oxygen isotope tracing of the Solar System

Oxygen isotope measurements have played a key role in establishing the way the solar system has formed. On Earth mass-dependent fractionation constrains conditions under which oxygen distributes itself among different phases. In the solar system, oxygen can experience kinetic fractionation as well, but the predominant cosmochemical signature is variability in 16O. This was first recognised in refractory inclusions, the oldest known materials in the solar system, where 4% excesses in 16O were apparent. Subsequently the range has increased to nearly 50% with the extreme values being an 8% excess of 16O (relative to terrestrial oxygen) in a chondrule, and to an apparent deficit in 16O of 40% in chondrite matrix. Originally interpreted as a nucleosynthetic signature, these compositions appear to be due to photochemical speciation either in the solar system or the precursor molecular cloud.
A Comparative Study Between the NGI Direct Simple Shear Apparatus and the Mikasa Direct Shear Apparatus

A comparative study of the NGI Direct Simple Shear Test (DSST) and the Mikasa Direct Shear Test (DST) is reported. Samples from Norwegian Drammen clay and Japanese Ariake clay were subjected to both types of test. An evaluation of these test results and a theoretical consideration on the different shearing mechanisms has shown that although the DST give generally higher stiffness and strength than the DSST, these differences can mainly be accounted for by the different shearing mechanisms and shearing rates. Sample disturbance due to transportation and handling may also be the reason for some of the difference. A technique for evaluation of sample disturbance in the DSST is presented and evaluated. Tests on undisturbed and remoulded Drammen clay consolidated to stresses much higher than the in situ effective overburden stress give almost identical results. Thus the effects of sample disturbance and in situ structure in the clay were eradicated.
Thermal convection and the convective regime diagram in super‐Earths

Numerical models of bottom‐heated thermal convection of highly compressible fluid with strongly temperature‐dependent viscosity are presented to understand how the Rayleigh number Ra and the temperature dependence of viscosity exert control over the regimes of thermal convection in massive super‐Earths. Thermodynamic properties of mantle materials are pressure dependent, but other material properties including the viscosity are not. A stagnant lid develops along the surface of the planet, when the viscosity contrast across the mantle due to temperature dependence r exceeds 106 at high Rayleigh number relevant to super‐Earths. The threshold in r, which increases with increasing Ra, is higher than that expected for the Earth from earlier Boussinesq models. The efficiency of convective heat transport measured by the Nusselt number Nu is considerably lower than that expected from Boussinesq models; Nu depends on Ra and r as Nu = 59 ⋅ r− 0.23 ⋅ (Ra/109)0.27, when r ≤ 105. Strong adiabatic compression significantly reduces the activity of hot ascending plumes especially at high r. At r relevant for super‐Earths, hot ascending plumes lose their buoyancy on their way and hardly reach the surface boundary: hot spot volcanism due to ascending plumes is probably suppressed on super‐Earths. The lithosphere is considerably thicker than that suggested by earlier Boussinesq models and is unlikely to show a plate‐like behavior.
Understanding salt-marsh accretion, Scolt Head Island, Norfolk, England

Measurements of surface sediment accretion have been obtained for Hut Marsh, Scolt Head Island, Norfolk, England, using sand marker horizons. More than eighty 1-m2 marker sites were deployed in October 1983, and vertical accretion measured at them in April and October 1986 and April 1987. Elevations relative to Ordnance Datum were established by levelling each site at the time of deployment. Data collected by Steers between 1935 and 1957 on the same marsh show a clear relationship between marsh elevation and sedimentation. The results of the current more detailed study, presented as mean annual accretion rates, indicate a complex pattern of sediment distribution at this macrotidal location. These data, together with the results of tidal flow monitoring in the creeks on Hut Marsh, show the importance of spatial and temporal patterns of sediment delivery and variations in depositional processes in determining the distribution of sedimentation across the marsh surface.
Defining environmental river flow requirements ? a review

Abstract. Around the world, there is an increasing desire, supported by national and regional policies and legislation, to conserve or restore the ecological health and functioning of rivers and their associated wetlands for human use and biodiversity. To achieve this, many organisations have developed methods for defining “environmental flows‿, i.e. the flow regime required in a river to achieve desired ecological objectives. This paper reviews the various methods available and suggests a simple categorisation of the methods into four types: look-up tables, desk-top analysis; functional analysis and hydraulic habitat modelling. No method is necessarily better than another; each may be suitable for different applications. Whilst look-up methods are easy and cheap to apply, they can be expensive to develop, are less accurate and more suitable for scoping studies; in contrast, although hydraulic habitat modelling is more expensive to apply, it is suitable for impact assessment at specific sites. Each method would need to be used within a wider decision-support framework. These are generally either objective-based to define a target flow regime for a specific desired river status, or scenario-based to indicate the relative merits of various flow regime options for the river environment. Keywords: environmental flow, instream flow, river habitat modelling, building block method, flow scenario analysis, objective setting.
Eocene-Oligocene transition in the Southern Ocean: History of water mass circulation and biological productivity

High-resolution records of carbon and oxygen isotopes and benthic foraminiferal accumulation rates for the Eocene-Oligocene section at Ocean Drilling Program Site 689(Maud Rise, Weddell Sea; paleodepth about 1500 m) were used to infer variations in paleoproductivity in relation to changes in climate and ventilation of the deeper-water column. The benthic foraminiferal abundance and isotope records show short-term fluctuations at periodicities of 100 and 400 ka, implying orbitally driven climatic variations. Both records suggest that intermediate-depth water chemistry and primary productivity changed in response to climate. During the Eocene, productivity increased during cold periods and during cold-to-warm transitions, possibly as a result of increased upwelling of nutrient-rich waters. In the Oligocene, in contrast, productivity maxima occurred during intervals of low d18O values (presumably warmer periods), when a proto–polar front moved to the south of the location of Site 689. This profound transition in climate-productivity patterns occurred around 37 Ma, coeval with rapid changes toward increasing variability of the oxygen and carbon isotope and benthic abundance records and toward larger-amplitude d18O fluctuations. Therefore, we infer that, at this time, temperature fluctuations increased and a proto–polar front formed in conjunction with the first distinct pulsations in size of the Antarctic ice sheet. We speculate that this major change might have resulted from an initial opening of the Drake Passage at 37 Ma, at least for surface- and intermediate-water circulation.
Paleocene initiation of Cenozoic uplift in Norway

Abstract The timing of Cenozoic surface uplift in NW Europe relies on the assumption that the sedimentary response in basins is synchronous with tectonic processes in the source areas. However, many of the phenomena commonly used to infer recent uplift may as well be a consequence of climate change and sea-level fall. The timing of surface uplift therefore remains unconstrained from the sedimentary record alone, and it becomes necessary to consider the constraints imposed by physically and geologically plausible tectonic mechanisms, which have a causal relation to an initiating agent. The gradual reversal of the regional stress field following the break-up produced minor perturbations to the thermal subsidence on the Norwegian Shelf and in the North Sea. Pulses of increased compression cannot be the cause of Cenozoic land surface uplift and accelerated Neogene basin subsidence. Virtually deformation-free regional vertical movements could have been caused by changes in the density column of the lithosphere and asthenosphere following the emplacement of the Iceland plume. A transient uplift component was produced as the plume displaced denser asthenosphere at the base of the lithosphere. This component decayed as the plume material cooled. Permanent uplift as a result of igneous underplating occurred in areas of a thin lithosphere (some Palaeozoic and Mesozoic basins) or for lithosphere under extension at the time of plume emplacement (the ocean-continent boundary). In areas of a thicker lithosphere (East Greenland, Scotland and Norway) plume emplacement may have triggered a Rayleigh-Taylor instability, causing partial lithospheric delamination and associated transient surface uplift at a decreasing rate throughout Cenozoic time. A possible uplift history for the adjacent land areas hence reads: initial transient surface uplift around the break-up time at 53 Ma caused by plume emplacement, and permanent tectonic uplift caused by lithospheric delamination and associated lithospheric heating. The permanent tectonic uplift increased through Cenozoic time at a decreasing rate. Denudation acted on this evolving topography and reduced the average surface elevation, but significantly increased the elevation of the summit envelope. The marked variations in the sedimentary response in the basins were caused by climatic variations and the generally falling eustatic level. This scenario bridges the gap between the ideas of Paleocene-Eocene uplift versus repeated Cenozoic tectonic activity: the tectonic uplift history was initiated by the emplacement of the Iceland plume, but continued throughout Cenozoic time as a consequence of early plume emplacement, with climatic and eustatic control on denudation. The mechanism is consistent with topography, heat flow, crustal structure, and the Bouguer gravity of Norway, and may be applicable also to East Greenland.
Retrieving Information from Scattered Photons in Medical Imaging

In many medical imaging modalities, as photons travel from the emission source to the detector, they are scattered by the biological tissue. Often this scatter is viewed as a phenomenon that degrades image quality, and most research is focused on designing methods for either discarding the scattered photons or correcting for scatter. However, the scattered photons also carry information about the tissue that they pass through, which can perhaps be extracted. In this research, we investigate methods to retrieve information from the scattered photons in two specific medical imaging modalities: diffuse optical tomography (DOT) and single photon emission computed tomography (SPECT). To model the scattering of photons in biological tissue, we investigate using the Neumann-series form of the radiative transport equation (RTE). Since the scattering phenomenon are different in DOT and SPECT, the models are individually designed for each modality. In the DOT study, we use the developed photon-propagation model to investigate signal detectability in tissue. To study this detectability, we demonstrate the application of a surrogate figure of merit, based on Fisher information, which approximates the Bayesian ideal observer performance. In the SPECT study, our aim is to determine if only the SPECT emission data acquired in list-mode (LM) format, including the scattered-photon data, can be used to compute the tissue-attenuation map. We first propose a path-based formalism to process scattered photon data, and follow it with deriving expressions for the Fisher information that help determine the information content of LM data. We then derive a maximum-likelihood expectation-maximization algorithm that can jointly reconstruct the activity and attenuation map using LM SPECT emission data. While the DOT study can provide a boost in transition of DOT to clinical imaging, the SPECT study will provide insights on whether it is worth exposing the patient to extra X-ray radiation dose in order to obtain an attenuation
Evaluation of the Polubarinova-Kochina Formula for the Dam Problem

The stationary problem of unconfined groundwater flow through a rectangular dam has been solved by P. Ya. Polubarinova-Kochina. In this paper the analytical formulas are used to obtain accurate numerical values for the phreatic surface and for the height of the seepage face. These values provide a reference with which to compare numerical methods for seepage problems.
Processes impacting on stratification in a region of freshwater influence: Application to Liverpool Bay

[1] Wind is shown to have an important influence on water column structure and residual circulation through a straining mechanism in the Liverpool Bay region of freshwater influence. By combining a long-term data set of water column observations collected from a mooring we estimate the horizontal gradients in temperature and salinity that are used to drive a one-dimensional turbulence model. Various combinations of the processes that impact the stratification are investigated, including the wind speed and direction, horizontal buoyancy gradient, and the tidal amplitude. From this we assess the significance of these processes and find that the effect of wind direction is important in determining water column structure. Both observations and a modeling study show that an offshore wind accelerates the development of stratification on the ebb tide and decelerates the destruction of stratification on the flood tide due to a “wind straining” process. The reverse situation occurs for an onshore wind.
Diachronous and independent histories of plutonism and mineralization in the Cornubian Batholith, southwest England

Concordant U-Pb dates of magmatic monazites in the dominant coarse-grained biotite (±muscovite) granites of the late Variscan Cornubian batholith demonstrate that the emplacement of the six main plutons was diachronous, ranging from 293.1 ±1.3 Ma (Carnmenellis) to 274.5 ± 1.4 Ma (Land's End, southern lobe). 40Ar-39Ar age spectra for magmatic muscovites confirm that cooling to about 320 °C at the present level of exposure was accomplished within 4 to 5 Ma in each intrusion. Moreover, age spectra for hydrothermal muscovites show that development of the major Sn (-Cu) lodes of the South Crofty mine commenced before 286 Ma, only 2 to 3 Ma after cooling of the hosting Cam Brea granite, a satellite of the Carnmenellis pluton. The older plutons had therefore approached ambient temperatures, and had even experienced intense hydrothermal activity, before emplacement of the youngest.
s-Lop : Modeling performance of shared memory MPI

Formal modeling of the cost of MPI primitives allows a machine independent representation, comparison and performance analysis of their underlying algorithms. Current accepted methods are all the off-springs of LogP, conceived to model the cost of inter-node point-to-point messages in networks of single-processor machines. As new supercomputers are built upon cheap commodity boards with a growing number of cores accessing hierarchical memories, intra-node communication becomes progressively more relevant. Techniques for shared memory communication, such as message segmentation and collectives, not based on point-to-point operations, are substantively different from their inter-node counterparts. This paper unveils the reasons for the poor fit of LogGP and the most recent models in this domain, logn P and m logn P, and proposes a new model named s-Lop, rooted on them, but addressing the challenge of accurately modeling shared memory MPI communications. Broadcast algorithms of mainstream MPI implementations, MPICH and Open MPI, are modeled and analyzed. 2015 Elsevier B.V. All rights reserved.
Plate Tectonics and Geomagnetic Reversals

The impetus for publishing this set of articles was the realization that, year after year, I and my students at Stanford were making copies (with varying degrees of legibility and legality) of the same classic articles on plate tectonics and geomagnetic reversals. At first we did this because there was so little material on the subject available, but even after the appearance of several excellent textbooks on plate tectonics and paleomagnetism, we still found ourselves using many of the original articles as supplementary reading. Students somehow seem to sense more acutely the excitement of discovery when they are given a sense of participation by having the scientist himself describe it to them. As scientists, most of us, when we write about our research, almost completely depersonalize it. Although there may be good reasons for this, it is a rather odd thing to do because we almost always feel a deep sense of personal involvement in our research. As some anomalous data fall into place or as a new idea begins to stir, the individual scientist, working perhaps late at night, experiences a feeling that surely is similar to the elation of the composer as he first hears new music in his mind, or to the exhilaration of the athlete as he breaks a record. Yet our science, as we write about it, tends to be science with the scientists left out. The effect is that we inadvertently may leave students with the impression that science is a routine, matter-of-fact business, which it surely isnt t. In the present book I have tried to put the scientists back into the scientific story. Wherever possible I have done this using the scientists own words, quoting from statements given to me in the spring of 1972 by many of the authors whose articles are included in this book. No pretense is made of presenting a complete history of research in plate tectonics and geomagnetic reversals. My intent, rather, is to convey something of the feeling of intense involvement and excitement experienced by earth scientists as they contributed to important new ideas.
Origin of Marble by Replacement of Gypsum in Carbonate Breccia Nappes, Carson Sink Region, Nevada: A Discussion

Recent discoveries from the Proterozoic McArthur Group and the Bungle Bungle Dolomite, of northern Australia, are relevant to the interpretations of the origin of certain marbles by replacement of gypsum put forward by Speed and Clayton (1975). The McArthur Group forms the second of three major groups which comprise the succession in the McArthur Basin (Plumb and Derrick 1975). The Tawallah Group, a dominantly arenite-volcanic sequence about 4 km thick, is overlain by a largely carbonate sequence up to 5.5 km thick, the McArthur Group (Plumb and Brown 1973), which is in turn unconformably overlain by an arenite-lutite sequence, the Roper Group, up to 5 km thick. The McArthur Group is about 1,550 to 1,450 m.y. old (Plumb and Sweet 1974), but the rocks are only mildly deformed and are unmetamorphosed. In mapping the McArthur Basin for the Bureau of Mineral Resources during 1960-61, J. W. Smith, H. G. Roberts, and Plumb commonly observed a red-brown very coarse-grained sideritic dolomitic marble within the fine-grained stromatolitic Amelia Dolomite of the McArthur Group. A spatial relationship was observed between the marble and copper minerali-
19.5L: Late‐News Paper: Effect of Diffuse Reflectance of Monitor Bezel Color on Human Performance, Preference, and Comfort

The effect of monitor bezel color (diffuse reflectance) on task performance, visual abilities, subjective comfort level, and preference in using software with graphical user interfaces was measured. Frame color had no effect on task performance or visual metrics (acuity, contrast sensitivity). Subjective ratings of discomfort were similarly higher at the end of 4 hours of work across all monitor bezel colors. The darkest bezel color was preferred by 2/3 of the participants at the end of 3 days, after using a different monitor bezel color on each day.