Graph reasoning with context-aware linearization for interpretable fact extraction and verification

This paper presents an end-to-end system for fact extraction and verification using textual and tabular evidence, the performance of which we demonstrate on the FEVEROUS dataset. We experiment with both a multi-task learning paradigm to jointly train a graph attention network for both the task of evidence extraction and veracity prediction, as well as a single objective graph model for solely learning veracity prediction and separate evidence extraction. In both instances, we employ a framework for per-cell linearization of tabular evidence, thus allowing us to treat evidence from tables as sequences. The templates we employ for linearizing tables capture the context as well as the content of table data. We furthermore provide a case study to show the interpretability our approach. Our best performing system achieves a FEVEROUS score of 0.23 and 53% label accuracy on the blind test data

The DRIFT Project: Searching for WIMPS with a Directional Detector

A low pressure time projection chamber for the detection of WIMPs is discussed. Discrimination against Compton electron background in such a device should be very good, and directional information about the recoil atoms would be obtainable. If a full 3-D reconstruction of the recoil tracks can be achieved, Monte Carlo studies indicate that a WIMP signal could be identified with high confidence from as few as 30 detected WIMP-nucleus scattering events.Comment: 5 pages, 3 figures. Presented at Dark 98, Heidelberg, July 1998, and to appear in conference proceeding

Surface analysis and treatment of extruded fluoride phosphate glass preforms for optical fiber fabrication

First published: 20 April 2016Fabrication of fluoride phosphate glass optical fibers using the extrusion method for preform fabrication has been studied using the commercial Schott N-FK51A glass. The extrusion step was found to create a surface layer of differing composition from the bulk glass material, leading to defects drawn down onto the optical fiber surface during fiber fabrication, resulting in high loss and fragile fibers. Similar phenomena have also been observed in other fluoride-based glasses. Removal of this surface layer from preforms prior to fiber drawing was shown to improve optical fiber loss from >5 dB/m to 0.5–1.0 dB/m. The removal of this surface layer is therefore necessary to produce low-loss fluoride phosphate optical fibers.Christopher A. G. Kalnins, Nigel A. Spooner, Tanya M. Monro, and Heike Ebendorff-Heideprie

Parameterized temporal exploration problems

In this paper we study the fixed-parameter tractability of the problem of deciding whether a given temporal graph G admits a temporal walk that visits all vertices (temporal exploration) or, in some problem variants, a certain subset of the vertices. Formally, a temporal graph is a sequence G = hG1, . . . , GLi of graphs with V (Gt) = V (G) and E(Gt) ⊆ E(G) for all t ∈ [L] and some underlying graph G, and a temporal walk is a timerespecting sequence of edge-traversals. We consider both the strict variant, in which edges must be traversed in strictly increasing timesteps, and the non-strict variant, in which an arbitrary number of edges can be traversed in each timestep. For both variants, we give FPT algorithms for the problem of finding a temporal walk that visits a given set X of vertices, parameterized by |X|, and for the problem of finding a temporal walk that visits at least k distinct vertices in V (G), parameterized by k. We also show W[2]-hardness for a set version of the temporal exploration problem for both variants. For the non-strict variant, we give an FPT algorithm for the temporal exploration problem parameterized by the lifetime of the input graph, and we show that the temporal exploration problem can be solved in polynomial time if the graph in each timestep has at most two connected components

Walnut Creek watershed restoration and water quality monitoring project : final report

https://ir.uiowa.edu/igs_tis/1048/thumbnail.jp

Rapid uranium-series age screening of carbonates by laser ablation mass spectrometry

AbstractUranium-series dating is a critical tool in quaternary geochronology, including paleoclimate work, archaeology and geomorphology. Laser ablation (LA) methods are not as precise as most isotope dilution methods, but can be used to generate calendar ages rapidly, expanding the range of dating tools that can be applied to late Pleistocene carbonates. Here, existing LA methods are revisited for corals (cold- and warm-water) and speleothems spanning the last 343 thousand years (ka). Measurement of the required isotopes (238U, 234U, 230Th and 232Th) is achieved by coupling a laser system to a multi-collector inductively-coupled-plasma mass spectrometer (MC-ICPMS) using a combination of a single central ion counter and an array of Faraday cups. Each sample analysis lasts for ∼4.3 min, and fifty samples can be measured in 12 h with an automated set up, after a day of sample preparation. The use of different standard materials and laser systems had no significant effect on method accuracy. Uncertainty on the measured (230Th/238U) activity ratios ranges from 5.4% to 7.6% for (230Th/238U) ratios equal to 0.7 and 0.1 respectively. Much of this uncertainty can be attributed to the heterogeneity of the standard material (230Th/238U) at the length scale of LA. A homogeneous standard material may therefore improve measurement uncertainty but is not a requirement for age-screening studies. The initial (234U/238U) of coral samples can be determined within ∼20‰, making it useful as a first indicator of open-system behaviour. For cold-water corals, success in determination of (232Th/238U) – which can affect final age accuracy – by LA depended strongly on sample heterogeneity. Age uncertainties (2 sigma) ranged from <0.8 ka at 0–10 ka, ∼1.5 ka at 20 ka to ∼15 ka at 125 ka. Thus, we have demonstrated that U-series dating by LA-MC-ICPMS can be usefully applied to a range of carbonate materials as a straightforward age-screening technique

Fluid and Halide Melt Inclusions of Magmatic Origin in the Ultramafic and Lower Banded Series, Stillwater Complex, Montana, USA

Fluid and melt inclusions trapped in igneous rocks below the platinum-group element (PGE)-rich J-M reef in the Stillwater Complex, Montana provide a physiochemical record of a continuum of high P-T magmatic-hydrothermal and low P-T metamorphic events. Magmatic-hydrothermal volatiles ranged from NaCl-dominated halide melts (>82 wt % NaClequiv) to more complex Na-Ca-K-Fe-Mn-Ba-Si-Al-Cl brines (28-79 wt % NaClequiv) that were trapped simultaneously with a moderate density carbonic fluid (CO2 ± CH4). Early primary inclusions containing immiscible brine and carbonic fluid were trapped in the granophyric albite-quartz core of a zoned pegmatite body in the Gabbronorite I unit at T of ∼ 700-715°C, and P between 4·3 and 5·6 kbar. The pegmatitic body crystallized from a fluid-saturated residual silicate liquid that was channeled through the cooling igneous stratigraphy. Approximately 500 m stratigraphically below the pegmatite, in the Ultramafic Series, early halide melt inclusions representing samples of formerly molten NaCl were trapped in unaltered primary olivine over a minimum range in temperature of 660-800°C. In the same olivine that hosts the halide melt inclusions, secondary brine inclusions with a composition similar to brines in the pegmatite were trapped over a minimum temperature range of 480-640°C. As hydrothermal activity continued during post-solidus cooling of the intrusion, quartz precipitation in the vuggy core of the pegmatite body trapped post-magmatic, immiscible brine and carbonic fluid inclusion assemblages that record a progressive decrease in fluid salinity, T and confining P from lithostatic to near-hydrostatic conditions. Late secondary inclusions containing regional metamorphic fluids were trapped in quartz in the pegmatite after cooling to zeolite-facies conditions. The late metamorphic fluids were low to moderate salinity, CaCl2-MgCl2-H2O solutions. Hydrous salt melts, magmatic brines, and non aqueous (carbonic) fluids may have coexisted and interacted throughout much of the late crystallization and post-magmatic history of the Stillwater Complex. Hence, the potential for interaction between exsolved magmatic volatiles and grain boundary-hosted sulfide minerals below the J-M reef at near-solidus temperatures, and the post-magmatic modification of the J-M reef PGE ore compositions by hydrothermal fluids are strongly indicate