The Lac au Renard Tephra Cluster: a record of Lochkovian (Lower Devonian) volcanism in the Indian Point Formation, Gaspe Peninsula, Quebec, Canada

Approximately twenty tephra beds, comprising the Lac au Renard Tephra Cluster (new), occur in the Rosebush Cove and Petit Portage members of the Indian Point Formation (Chaleurs Group) on the Gaspe Peninsula of Quebec, Canada. The tephra beds range in thickness from <1.0 cm to 82 cm and occur in a mudrock-dominated sequence with coarser tempestite interbeds. Mineralogically and texturally graded accumulations of phenocrysts mark the bases of the thickest tephra beds. Early diagenetic concretions in one composite tephra preserve pre-compaction fabrics and original hypocrystalline textures with microphenocrysts and devitrified glass shards. The presence of plagioclase, quartz, K-feldspar, biotite, apatite, and zircon suggest a rhyolitic source. The coarseness of the microphenocrysts in the basal accumulations, along with the abundance and thickness of the tephras, suggest that deposition in the Gaspe area was in a proximal position relative to the volcanic source. The zonal graptolites Monograptus praehercynicus and Monograptus aequabilis ssp. from the Petit Portage Member indicate a middle Lochkovian age for the Lac au Renard Tephra Cluster of the Indian Point Formation. Correlation with the tephra cluster that includes the Judds Falls Bentonite in the New Scotland Formation and other possible tephras in the Kalkberg Formation (Helderberg Group) of New York and the Corriganville and Mandata formations of Pennsylvania is likely. The graptolite fauna of the Indian Point and probable correlations to New York may provide additional biostratigraphic constraints on a U–Pb zircon radiometric age determination of 417.6 Ma from New York that has been used to estimate the age of the Silurian–Devonian boundary.Une vingtaine d’amoncellements de téphras, dont l’amas de téphras du lac au Renard (nouvel amas), sont présents dans les membres de l’anse Rosebush et de Petit Portage de la Formation d’Indian Point (groupe de Chaleurs) en Gaspésie, au Québec, Canada. Les strates de téphras, dont l’épaisseur varie entre <1,0 cm et 82 cm, se manifestent dans une séquence à prédominance de pélite interlitée de tempestite plus grossière. Des accumulations de phénocristaux dont la composition minéralogique et la texture varient progressivement marquent les bases des strates les plus épaisses de téphras. Des concrétions diagénétiques précoces dans un amas de téphras composite préservent les fabriques préalables à la compaction et les textures hémicristallines originales en compagnie de microphénocristaux et d’éclats de verre dévitrifiés. La présence de plagioclase, de quartz, de feldspath potassique, de biotite, d’apatite et de zircon laisse supposer une source rhyolitique. La grossièreté des microphénocristaux dans les accumulations basales de même que l’abondance et l’épaisseur des amas de téphras permettent de supposer que le dépôt des téphras en Gaspésie est survenu à proximité d’une source volcanique. Les graptolites zonaux – sous-espèces Monograptus praehercynicus et Monograptus aequabilis – du membre de Petit Portage confèrent à l’amas de téphras du lac au Renard de la Formation d’Indian Point un âge le situant au Lochkovien moyen. Il est probable qu’il puisse être corrélé à l’amas de téphras englobant la bentonite des chutes Judds dans la Formation de New Scotland et d’autres téphras possibles dans la Formation de Kalkberg (groupe de Helderberg) de New York ainsi que les formations de Corriganville et de Mandata en Pennsylvanie. La faune de graptolites d’Indian Point et les corrélations probables avec New York pourraient imposer d’autres contraintes biostratigraphiques à la datation radiométrique U–Pb sur zircon de 417,6 Ma obtenue de New York qui a servi à l’estimation de l’âge de la limite siluro-dévonienne

Distribution Archaeology: Survey, Mapping, and Analysis of Surface Archaeological Materials in the Green River Basin, Wyoming

Archaeology in America today is in a quandary. This is especially true for that portion of the profession responsible for investigating and managing the surface archaeology of large tracts of land. The quandary concerns how to maximize the amount of information about the archaeology of an area given finite budgets. Predictive modeling, a technique for projecting knowledge derived from a sample to its universe, has been proposed as one response to this dilemma. We shall present another response, distributional archaeology, which is designed to collect quality information about the archaeological record and is consistent with the formation and structure of that data base. Inherent in all archaeological modeling attempts are assumptions about the nature of the archaeological record. These assumptions must be questioned in light of the formation processes that are responsible for the archaeology potentially available to us. Before examining how the archaeological record is formed, we briefly examine some of the prejudgments archaeologists make about their data

Distribution Archaeology: Survey, Mapping, and Analysis of Surface Archaeological Materials in the Green River Basin, Wyoming

Archaeology in America today is in a quandary. This is especially true for that portion of the profession responsible for investigating and managing the surface archaeology of large tracts of land. The quandary concerns how to maximize the amount of information about the archaeology of an area given finite budgets. Predictive modeling, a technique for projecting knowledge derived from a sample to its universe, has been proposed as one response to this dilemma. We shall present another response, distributional archaeology, which is designed to collect quality information about the archaeological record and is consistent with the formation and structure of that data base. Inherent in all archaeological modeling attempts are assumptions about the nature of the archaeological record. These assumptions must be questioned in light of the formation processes that are responsible for the archaeology potentially available to us. Before examining how the archaeological record is formed, we briefly examine some of the prejudgments archaeologists make about their data

Migrating publications: how do technical writers bound an uncertain problem space?

This paper describes writer activities to define and resolve information migration issues that retard throughput of new information into technical publications in a production-focused work environment. The paper also reports the results of a questionnaire administered to a convenience sample of technical writers using ISO 8879 Standard, Generalized Markup Language (SGML), examining their information needs and information-seeking activities

Spatiotemporal Crime Analysis

There has been a rise in the use of visual analytic techniques to create interactive predictive environments in a range of different applications. These tools help the user sift through massive amounts of data, presenting most useful results in a visual context and enabling the person to rapidly form proactive strategies. In this paper, we present one such visual analytic environment that uses historical crime data to predict future occurrences of crimes, both geographically and temporally. Due to the complexity of this analysis, it is necessary to find an appropriate statistical method for correlative analysis of spatiotemporal data, as well as design an interface to present these results to the user in a timely fashion. In our approach, we make use of the Dynamic Covariance Kernel Density Estimation (DCKDE) method to visualize the data in a geospatial context. The results are represented as a heat map showing the areas with a higher probability of crime. In the temporal context, a modified Seasonal Trend decomposition based on Loess (STL) is used to decompose time series signals in order to isolate trends that are used to predict the number of crime occurrences in pre-defined areas for a given time interval. These techniques were applied to Tippecanoe County to make predictions for the next time step. We evaluated the results of our prediction technique against observed data. We note that our methods are applicable to any situation where incidents may have a local spatial correlation

Comparative metagenomics of Daphnia symbionts

BACKGROUND: Shotgun sequences of DNA extracts from whole organisms allow a comprehensive assessment of possible symbionts. The current project makes use of four shotgun datasets from three species of the planktonic freshwater crustaceans Daphnia: one dataset from clones of D. pulex and D. pulicaria and two datasets from one clone of D. magna. We analyzed these datasets with three aims: First, we search for bacterial symbionts, which are present in all three species. Second, we search for evidence for Cyanobacteria and plastids, which had been suggested to occur as symbionts in a related Daphnia species. Third, we compare the metacommunities revealed by two different 454 pyrosequencing methods (GS 20 and GS FLX). RESULTS: In all datasets we found evidence for a large number of bacteria belonging to diverse taxa. The vast majority of these were Proteobacteria. Of those, most sequences were assigned to different genera of the Betaproteobacteria family Comamonadaceae. Other taxa represented in all datasets included the genera Flavobacterium, Rhodobacter, Chromobacterium, Methylibium, Bordetella, Burkholderia and Cupriavidus. A few taxa matched sequences only from the D. pulex and the D. pulicaria datasets: Aeromonas, Pseudomonas and Delftia. Taxa with many hits specific to a single dataset were rare. For most of the identified taxa earlier studies reported the finding of related taxa in aquatic environmental samples. We found no clear evidence for the presence of symbiotic Cyanobacteria or plastids. The apparent similarity of the symbiont communities of the three Daphnia species breaks down on a species and strain level. Communities have a similar composition at a higher taxonomic level, but the actual sequences found are divergent. The two Daphnia magna datasets obtained from two different pyrosequencing platforms revealed rather similar results. CONCLUSION: Three clones from three species of the genus Daphnia were found to harbor a rich community of symbionts. These communities are similar at the genus and higher taxonomic level, but are composed of different species. The similarity of these three symbiont communities hints that some of these associations may be stable in the long-term

The Large and Small Scale Structures of Dust in the Star-Forming Perseus Molecular Cloud

We present an analysis of ~3.5 square degrees of submillimetre continuum and extinction data of the Perseus molecular cloud. We identify 58 clumps in the submillimetre map and we identify 39 structures (`cores') and 11 associations of structures (`super cores') in the extinction map. The cumulative mass distributions of the submillimetre clumps and extinction cores have steep slopes (alpha ~ 2 and 1.5 - 2 respectively), steeper than the Salpeter IMF (alpha = 1.35), while the distribution of extinction super cores has a shallow slope (alpha ~ 1). Most of the submillimetre clumps are well fit by stable Bonnor-Ebert spheres with 10K < T < 19K and 5.5 < log_10(P_ext/k) < 6.0. The clumps are found only in the highest column density regions (A_V > 5 - 7 mag), although Bonnor-Ebert models suggest that we should have been able to detect them at lower column densities if they exist. These observations provide a stronger case for an extinction threshold than that found in analysis of less sensitive observations of the Ophiuchus molecular cloud. The relationship between submillimetre clumps and their parent extinction core has been analyzed. The submillimetre clumps tend to lie offset from the larger extinction peaks, suggesting the clumps formed via an external triggering event, consistent with previous observations.Comment: 38 pages, 12 figures, accepted by Astrophysical Journal slight changes to original due to a slight 3" error in the coordinates of the SCUBA ma

Indicator patterns of forced change learned by an artificial neural network

Many problems in climate science require the identification of signals obscured by both the "noise" of internal climate variability and differences across models. Following previous work, we train an artificial neural network (ANN) to identify the year of input maps of temperature and precipitation from forced climate model simulations. This prediction task requires the ANN to learn forced patterns of change amidst a background of climate noise and model differences. We then apply a neural network visualization technique (layerwise relevance propagation) to visualize the spatial patterns that lead the ANN to successfully predict the year. These spatial patterns thus serve as "reliable indicators" of the forced change. The architecture of the ANN is chosen such that these indicators vary in time, thus capturing the evolving nature of regional signals of change. Results are compared to those of more standard approaches like signal-to-noise ratios and multi-linear regression in order to gain intuition about the reliable indicators identified by the ANN. We then apply an additional visualization tool (backward optimization) to highlight where disagreements in simulated and observed patterns of change are most important for the prediction of the year. This work demonstrates that ANNs and their visualization tools make a powerful pair for extracting climate patterns of forced change.Comment: The first version of this manuscript has been submitted to the Journal of Advances in Modeling Earth Systems (JAMES), 202

Abundances of Molecular Species in Barnard 68

Abundances for 5 molecules (C18O, CS, NH3, H2CO, and C3H2) and 1 molecular ion (N2H+) and upper limits for the abundances of 1 molecule (13CO) and 1 molecular ion (HCO+) are derived for gas within the Bok globule Barnard 68 (B68). The abundances were determined using our own BIMA millimeter interferometer data and single-dish data gathered from the literature, in conjunction with a Monte Carlo radiative transfer model. Since B68 is the only starless core to have its density structure strongly constrained via extinction mapping, a major uncertainty has been removed from these determinations. All abundances for B68 are lower than those derived for translucent and cold dense clouds, but perhaps only significantly for N2H+, NH3, and C3H2. Depletion of CS toward the extinction peak of B68 is hinted at by the large offset between the extinction peak and the position of maximum CS line brightness. Abundances derived here for C18O and N2H+ are consistent with other, recently determined values at positions observed in common.Comment: 16 pages, 1 figure, accepted by AJ, typo corrected, reference removed in Section 4.