OSL investigations at Hardisty, Alberta, Canada: Sections HD03, HD04 & HD05

This report is concerned with optically stimulated luminescence (OSL) investigations of a number of sediment stratigraphies in the Battle River Valley area, near Hardisty, east-central Alberta. Archaeological investigations in this region, led by Rob Wondrasek, have identified thousands of historical artefacts, including projectile points and lithic fragments indicative of occupation. Ken Munyikwa visited the archaeological sites at Hardisty in June 2014 and January 2015 to sample key units within the sediment stratigraphies for OSL dating. The sediments associated with the artefacts were appraised through five profiles, Hardisty-1 (HD01) to Hardisty-5 (HD05), comprised of 43 field-profiling and 14 dating samples. Profiles HD01 and HD02 were sampled in June 2014; and profiles HD03 through to HD05 in January 2015. The dating questions associated with these materials relate to the age of artefact-bearing horizon, through dating the enclosing sediments above and beneath the archaeological soil, it should be possible to provide terminus post quem (TPQ) and terminus ante quem (TAQ) on the age of the artefacts. The conventional quartz SAR OSL approach was examined as a potential method for providing the depositional ages of the sediment enclosing the artefacts. Luminescence profiling during fieldwork had revealed stratigraphically progressive IRSL and OSL signals, indicating sediment with dating potential. Dose rate estimates from these sediments were assessed using a combination of high resolution gamma spectrometry (HRGS) and thick source beta counting (TSBC), reconciled with each other, water contents and modelled micro-dosimetry. Where appropriate, the external gamma dose rates received at the position of the dating sample were reconstructed from the adjacent bulk gamma spectrometry samples, yielding wet gamma dose rates between 0.42 and 0.54 mGy a-1, which are comparable with those recorded at each sampling position. Equivalent doses were determined by OSL from 16-48 aliquots of quartz per sample (depending on quartz yields) using a single-aliquot-regenerative (SAR) approach. The material exhibited good OSL sensitivity and produced acceptable SAR internal quality control performance. Radial plotting methods revealed some heterogeneity in the equivalent dose distributions of each sample, indicating that each sample enclosed mixed-age materials, reflecting variable bleaching at deposition. The field profiles provide some measure of control on this. Luminescence ages were calculated using standard microdosimetric models, with uncertainties that combined measurement and fitting errors from the SAR analysis, all dose rate evaluation uncertainties, and allowance for the calibration uncertainties of the sources and reference materials. The quartz OSL ages reported here for the sand sequences at HD03 to HD05, contribute to the expanding catalogue of chronological data on the depositional sequences at Hardisty, and further, provide the means to assess the temporal and spatial distribution of artefacts across the site. The sediment chronologies established for each profile are internally and mutually coherent, spanning at HD03 from 7.3 ± 0.3 ka (SUTL2778) to 9.0 ± 0.5 ka (SUTL2780), at HD04 from 7.0 ± 0.3 ka (SUTL2781) to 8.3 ± 0.4 ka (SUTL2782), and at HD05 from 8.3 ± 0.5 ka (SUTL2783) to 9.6 ± 0.6 ka (SUTL2785). The field profile at HD05 reveals some complexity to its depositional history, with notable maxima and inversions in intensities from 150cm depth, potentially reflecting reworking and re-deposition of sediment within this sequence. TAQ for this phase of reworking is provided by the youngest unit examined in the profile, which at 7.5 ± 0.6 ka (SUTL2784), is consistent with the occupational phase recorded in the adjacent sections. The sediment chronologies established in this dating campaign, and in the 2014 campaign, are synchronous suggesting contemporaneous deposition across the site, and presumably, with local knowledge, scope for further age modelling including the use of Bayesian methods to refine the TAQ and TPQ age limits

Fracture surface analysis in composite and titanium bonding: Part 1: Titanium bonding

Fractured lap shear Ti 6-4 adherends bonded with polyphenyquinoxaline (PPQ) and polysulfone were analyzed. The effects of adherend pretreatment, stress level, thermal aging, anodizing voltage, and modified adhesive of Ti 6-4 adherend bonded with PPQ on lap shear strength were studied. The effect of adherend pretreatment on lap shear strength was investigated for PS samples. Results of scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS) used to study the surface topography and surface composition are also discussed

University of Sheffield TREC-8 Q & A System

The system entered by the University of Sheffield in the question answering track of TREC-8 is the result of coupling two existing technologies - information retrieval (IR) and information extraction (IE). In essence the approach is this: the IR system treats the question as a query and returns a set of top ranked documents or passages; the IE system uses NLP techniques to parse the question, analyse the top ranked documents or passages returned by the IR system, and instantiate a query variable in the semantic representation of the question against the semantic representation of the analysed documents or passages. Thus, while the IE system by no means attempts “full text understanding", this approach is a relatively deep approach which attempts to work with meaning representations. Since the information retrieval systems we used were not our own (AT&T and UMass) and were used more or less “off the shelf", this paper concentrates on describing the modifications made to our existing information extraction system to allow it to participate in the Q & A task

Bayesian analysis of 210Pb dating

In many studies of environmental change of the past few centuries, 210Pb dating is used to obtain chronologies for sedimentary sequences. One of the most commonly used approaches to estimate the ages of depths in a sequence is to assume a constant rate of supply (CRS) or influx of `unsupported' 210Pb from the atmosphere, together with a constant or varying amount of `supported' 210Pb. Current 210Pb dating models do not use a proper statistical framework and thus provide poor estimates of errors. Here we develop a new model for 210Pb dating, where both ages and values of supported and unsupported 210Pb form part of the parameters. We apply our model to a case study from Canada as well as to some simulated examples. Our model can extend beyond the current CRS approach, deal with asymmetric errors and mix 210Pb with other types of dating, thus obtaining more robust, realistic and statistically better defined estimates.Comment: 22 Pages, 4 Figure

Millimetre and submillimetre molecular line observations of the reflection nebula NGC 2023

Observations in the CO J = 2 - 1, CO J = 3 - 2 and HCO+ J = 4 - 3 transitions of the molecular cloud associated with NGC 2023 are presented. The observations reveal the complex structure of the gas in the surrounding cloud, and show the presence of several hot-spots which may represent separate bodies of gas. A search has been made for the source of excitation of two nearby groups of Herbig-Haro objects recently discovered by Malin et al. (1987). No such objects can be clearly identified from the data. CO J = 3 - 2 spectra taken at positions lying on the CO J = 1 - 0 shell observed by Gatley et al. (1987) show marked enhancements in peak line strength relative to coincident CO J = 2 - 1 data. By contrast, no such enhancements are observed away from the shell. Observations of the submillimeter wavelength HCO+ J = 4 - 3 transition show that the line strength is greatest in the vicinity of the shell structure. Simple large velocity gradient modeling of the excitation conditions of the shell material suggests that the gas may be hot (Tkin ~ 140 K), dense, and optically thin

Reading between the lines: attitudinal expressions in text

This is a brief overview of the starting points a project currently proposed and under evaluation by funding agencies. We discuss some of the linguistic methodology we plan to employ to idenitify and analyze attitudinal expressions in text, and touch briefly on how to evaluate our future results

Low energy proton bidirectional anisotropies and their relation to transient interplanetary magnetic structures: ISEE-3 observations

It is known that the interplanetary medium in the period approaching solar maximum is characterized by an enhancement in the occurrence of transient solar wind streams and shocks and that such systems are often associated with looplike magnetic structures or clouds. There is observational evidence that bidirectional, field aligned flows of low energy particles could be a signature of such looplike structures, although detailed models for the magnetic field configuration and injection mechanisms do not exist at the current time. Preliminary results of a survey of low energy proton bidirectional anisotropies measured on ISEE-3 in the interplanetary medium between August 1978 and May 1982, together with magnetic field data from the same spacecraft are presented

Forage herbs improve mineral composition of grassland herbage

Provision of an adequate mineral supply in the diets of ruminants fed mainly on grassland herbage can present a challenge if mineral concentrations are suboptimal for animal nutrition. Forage herbs may be included in grassland seed mixtures to improve herbage mineral content, although there is limited information about mineral concentrations in forage herbs. To determine whether herbs have greater macro- and micromineral concentrations than forage legumes and grasses, we conducted a 2-year experiment on a loamy-sand site in Denmark sown with a multi-species mixture comprised of three functional groups (grasses, legumes and herbs). Herb species included chicory (Cichorium intybus L.), plantain (Plantago lanceolata L.), caraway (Carum carvi L.) and salad burnet (Sanguisorba minor L.). We also investigated the effect of slurry application on the macro- and micromineral concentration of grasses, legumes and herbs. In general, herbs had greater concentrations of the macrominerals P, Mg, K and S and the microminerals Zn and B than grasses and legumes. Slurry application indirectly decreased Ca, S, Cu and B concentrations of total herbage because of an increase in the proportion of mineral-poor grasses. Our study indicates that including herbs in forage mixtures is an effective way of increasing mineral concentrations in herbage