Dendroglaciological Dating of a Little Ice Age Glacial Advance at Moving Glacier, Vancouver Island, British Columbia

Dendrochronological investigations at Moving Glacier provide the first calendar-dating of a Little Ice Age glacier advance on Vancouver Island. In 1931, Moving Glacier was within 30 to 50 m of a distinct trimline and terminal moraine marking its maximum Little Ice Age extent. A reconnaissance of the site in 1993 revealed the presence of sheared in situ stumps and detrital trunks inside the 1931 ice limit. Sampling in 1994 showed the site was covered by a mature subalpine forest prior to the glacial advance which overrode the site after 1718 A.D. Following this period of expansion, which saw Moving Glacier expand to its maximum Little Ice Age position after 1818 A.D., the glacier apparently experienced only minimal retreat prior to first being photographed in 1931.Des recherches en dendrochronologie menées sur le glacier Moving ont permis de dater l'évolution d'un glacier au Petit Âge glaciaire. En 1931, Le glacier Moving était situé entre 30 et 50 m d'un épaulement et d'une moraine frontale correspondant à sa limite d'expansion maximale au Petit Âge glaciaire. L'exploration du site en 1993 a permis de découvrir des souches et des débris de bois in situ à l'intérieur de la limite glaciaire de 1931. Un échantillonnage effectué en 1994 a montré que le site était recouvert d'une forêt subalpine mûre avant l'avancée glaciaire qui a bouleversé le site après 1718 ap. J.-C. Après la période d'expansion, qui a permis au glacier d'atteindre sa limite maximale après 1818 ap. J.-C, le glacier a connu un recul minimal avant d'être photographié en 1931.Dendrochnronologische Forschungen am Moving-Gletscher ergeben die erste Kalenderdatierung eines GletschervorstoBes wâhrend der kleinen Eiszeit auf der Insel Vancouver. 1931 befand sich der Moving-Gletscher innerhalb der 30 bis 50 m einer klaren Abflachung und der Endmorâne, was seiner maximalen Ausdehnung in der kleinen Eiszeit entsprach. 1993 fand man bei der Erkundung des Platzes in situ abgescherte Baumstùmpfe und Trùmmer von Baumstâmmen innerhalb der Eisgrenze von 1931. 1994 zeigte eine Probenentnahme, daf3 der Platz mit einem ausgewachsenen subalpinen WaId bewachsen war, bevor der glaziale VorstoB den Platz nach 1718 u.Z. verwandelte. Nach dieser Ausdehnungs-periode, in welcher der Moving-Gletscher nach 1818 u.Z. seine maximale Position in der kleinen Eiszeit erreichte, hat der Gletscher offenbar nur einen minimalen Rùckzug vollzogen, bevor er 1931 zum 1. Mal photographiert wurde

Dating the Morris House: A Study of Heritage Value in Nova Scotia

In 2009, a group of concerned citizens in Halifax rallied to the banner of The Heritage Trust of Nova Scotia and the Ecology Action Centre to save an 18th century building from demolition. Their case for preserving the building hinged on its unique heritage value, it having formerly housed the office of Charles Morris,Nova Scotia’s first Chief Surveyor. Thanks to their efforts, the Morris House was temporarily relocated to a nearby vacant lot while a new apartment building gradually rose in its place. Although researchers had believed the Morris House pre-dated 1781, the year of Charles Morris’s death, its precise age was unknown at the time of the move. Through a combination of dendroarchaeological, cartographic, and documentary evidence, our research significantly alters previous understandings of the building’s history and complicates the narrative advanced by heritage advocates in its defense. In doing so, it also raises questions about the interface between empirical research and the socio-political factors influencing the determination of heritage value. En 2009, un groupe de citoyen s’est réuni sous les auspices de The Heritage Trust of Nova Scotia et The Ecology Action Centre concerné par la sauvegarde d’un bâtiment du 18e siècle menacé de démolition. Connu sous le nom de Morris Building en raison de liens possibles avec Charles Morris (père), premier chef arpenteur géomètre de la Nouvelle-Écosse, le bâtiment a été déplacé de sa position initiale du 1273 de la rue Hollis de Halifax à un site temporaire à proximité, car un bloc appartement devait y être construit. Bien que les spécialistes croyaient que le Morris Building datait d’avant 1781, son âge exact restait inconnu. Avec la combinaison de recherches dendroarchéologiques, cartographiques et documentaires, notre étude modifie significativement la compréhension de l’histoire du bâtiment et complique le tableau avancé par les défenseurs de la tradition dans la conservation de cet héritage. Ce faisant, la question est posée sur les chevauchements et relations entre la recherche empirique et les facteurs socio-politiques qui influencent la détermination de la valeur historique d’un site

On the redistributive power of pensions

We study the tradeoff between efficiency and redistribution in a model with overlapping generations, extensive labor supply, and perfect financial markets. The government instruments are a pension scheme and a age-independent nonlinear income tax schedule. At the second-best optimum, the pension system constrains the agents’ labor supply behavior, forcing them to work to achieve a required lifetime performance. Income taxes affect labor supply directly, but also indirectly through pension incentives. The indirect effect of taxes counteracts the usual forces in the efficiency-redistribution tradeoff: through the interplay with the pension system, decreasing taxes induces redistribution and reduces productive efficiency

Scaling relations from Sunyaev-Zel'dovich effect and Chandra X-ray measurements of high-redshift galaxy clusters

We present Sunyaev-Zel'dovich Effect (SZE) scaling relations for 38 massive galaxy clusters at redshifts 0.14 ≤ z≤ 0.89, observed with both the Chandra X-ray Observatory and the centimeter-wave SZE imaging system at the BIMA and OVRO interferometric arrays. An isothermal β-model with the central 100 kpc excluded from the X-ray data is used to model the intracluster medium and to measure global cluster properties. For each cluster, we measure the X-ray spectroscopic temperature, SZE gas mass, total mass, and integrated Compton y-parameters within r2500. Our measurements are in agreement with the expectations based on a simple self-similar model of cluster formation and evolution. We compare the cluster properties derived from our SZE observations with and without Chandra spatial and spectral information and find them to be in good agreement. We compare our results with cosmological numerical simulations and find that simulations that include radiative cooling, star formation, and feedback match well both the slope and normalization of our SZE scaling relations

Dendrochronological dating of coal mine workings at the Joggins Fossil Cliffs, Nova Scotia, Canada

Joggins, Nova Scotia was one of the first places in North America where coal was mined. In this paper we employ dendrochronology to date timber pit props preserved within relic coal mine workings on the closely adjacent Fundy and Dirty seams. These remains comprise a system of adits created through ‘room and pillar’ mining. Of the seventy-three samples collected, forty-eight were successfully cross-dated against a local red spruce (Picea rubens Sarg.) master chronology thereby establishing the year in which each individual sample was cut as a live tree. Results indicate cut dates of 1849-1875 which are generally consistent with written archival records of mining activity on these coal seams. Our analysis of fourteen separate adits allows us to distinguish two phases of mining. Most adits (numbers 1-9 and 11-12 with cut dates of 1849-1868) are relics of an initial operation by the General Mining Association (1865-1871), which opened a mine entered at beach level. Dendrochronological dates preceding the opening of this mine may suggest that timber stockpiled from the nearby Joggins Mine (opened 1847) was used in its construction. The remaining adits (numbers 10 and 13-14 with cut dates of 1873-1875) are probably relics of a later mine opened by the Joggins Coal Mining Company (1872-1877). Although this mine was centered ~500 m inland, its western peripheral workings passed through the earlier workings to the shore. Findings improve knowledge of the industrial archaeology of the UNESCO World Heritage Site and help refine the regional master red spruce chronology for future dendrochronological studies

Fast-Neutron Activation of Long-Lived Isotopes in Enriched Ge

We measured the production of \nuc{57}{Co}, \nuc{54}{Mn}, \nuc{68}{Ge}, \nuc{65}{Zn}, and \nuc{60}{Co} in a sample of Ge enriched in isotope 76 due to high-energy neutron interactions. These isotopes, especially \nuc{68}{Ge}, are critical in understanding background in Ge detectors used for double-beta decay experiments. They are produced by cosmogenic-neutron interactions in the detectors while they reside on the Earth's surface. These production rates were measured at neutron energies of a few hundred MeV. We compared the measured production to that predicted by cross-section calculations based on CEM03.02. The cross section calculations over-predict our measurements by approximately a factor of three depending on isotope. We then use the measured cosmic-ray neutron flux, our measurements, and the CEM03.02 cross sections to predict the cosmogenic production rate of these isotopes. The uncertainty in extrapolating the cross section model to higher energies dominates the total uncertainty in the cosmogenic production rate.Comment: Revised after feedback and further work on extrapolating cross sections to higher energies in order to estimate cosmic production rates. Also a numerical error was found and fixed in the estimate of the Co-57 production rat

Radio Sources Toward Galaxy Clusters at 30 GHz

Extra-galactic radio sources are a significant contaminant in cosmic microwave background and Sunyaev-Zel'dovich effect experiments. Deep interferometric observations with the BIMA and OVRO arrays are used to characterize the spatial, spectral, and flux distributions of radio sources toward massive galaxy clusters at 28.5 GHz. We compute counts of mJy source fluxes from 89 fields centered on known massive galaxy clusters and 8 non-cluster fields. We find that source counts in the inner regions of the cluster fields (within 0.5 arcmin of the cluster center) are a factor of 8.9 (+4.3,-2.8) times higher than counts in the outer regions of the cluster fields (radius greater than 0.5 arcmin). Counts in the outer regions of the cluster fields are in turn a factor of 3.3 (+4.1,-1.8) greater than those in the non-cluster fields. Counts in the non-cluster fields are consistent with extrapolations from the results of other surveys. We compute spectral indices of mJy sources in cluster fields between 1.4 and 28.5 GHz and find a mean spectral index of alpha = 0.66 with an rms dispersion of 0.36, where flux is proportional to frequency raised to negative alpha. The distribution is skewed, with a median spectral index of 0.72 and 25th and 75th percentiles of 0.51 and 0.92, respectively. This is steeper than the spectral indices of stronger field sources measured by other surveys.Comment: 32 pages, 6 figures, accepted to A