2,768 research outputs found

    TRA-928: FISH BARRIER MITIGATION OF AN OVERSTEEPENED CULVERT WITHIN SAUGEEN FIRST NATION RESERVE

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    A deteriorated concrete box culvert conveying a tributary of the Saugeen River under Highway 21 in Ontario had reached the end of its lifespan and was in need of replacement. The tributary supports a diverse range of coldwater fish species such as Rainbow Trout; however, fish passage, particularly upstream migration, has been cut off since the culvert and highway were constructed over seventy-five years ago. Specifically, fish passage has been hindered by shallow sheet flow along the sixty metre flat bottom, excessive velocities associated with the smooth, seven percent gradient, and a perched barrier at the downstream outlet. A key component of the culvert replacement was an effort to improve the overall condition of the tributary’s natural environment, including the promotion of fish passage and migration opportunities. The culvert replacement project undertaken by the Ontario Ministry of Transportation (MTO) and MMM Group, coupled resources with the Saugeen Ojibway Nation (SON) Environment office, Parsons biologists, and Aquafor geomorphologists. The most ecologically sensitive replacement methodology of an open bottom structure was not viable for this project as it would have required a full closure of the Highway for approximately four months. A circular steel pipe culvert installed through tunneling was designed to by-pass and replace the existing concrete box culvert. In an effort to mitigate the current barriers to fish with the new pipe culvert, a prefabricated corrugated steel slip liner with engineered baffle arrangement was integrated into the design. The baffle configuration and geometry was designed by Jason Duguay (Université de Sherbrooke) and Ken Hannaford (Gov. NFLD), and the slip liner construction by the Corrugated Steel Pipe Institute. Construction of the new culvert and slip liner was completed in December, 2015, and a two year monitoring program will be undertaken to assess the effectiveness of barrier mitigation and geomorphic stability of the tributary

    The Heavy Element Enrichment of Lyman alpha Clouds in the Virgo Supercluster

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    Using high S/N STIS echelle spectra (FWHM=7 km/s) of 3C 273, we constrain the metallicities of two Lya clouds in the vicinity of the Virgo cluster. We detect C II, Si II, and Si III absorption lines in the Lya absorber at z = 0.00530. Previous observations with FUSE have revealed Ly beta - Ly theta lines at this redshift, thereby accurately constraining N(H I). We model the ionization of the gas and derive [C/H] = -1.2^{+0.3}_{-0.2}, [Si/C] = 0.2+/-0.1, and log n_{H} = -2.8+/-0.3. The model implies a small absorber thickness, ~70 pc, and thermal pressure p/k ~ 40 cm^{-3} K. It is most likely that the absorber is pressure confined by an external medium because gravitational confinement would require a very high ratio of dark matter to baryonic matter. Based on Milky Way sight lines in which carbon and silicon abundances have been reliably measured in the same interstellar cloud (including new measurements presented herein), we argue that the overabundance of Si relative to C is not due to dust depletion. Instead, this probably indicates that the gas has been predominately enriched by Type II supernovae. Such enrichment is most plausibly provided by an unbound galactic wind, given the absence of galaxies within a projected distance of 100 kpc and the presence of galaxies capable of driving a wind at larger distances. We also constrain the metallicity and physical conditions of the Virgo absorber at z = 0.00337 based on detections of O VI and H I and an upper limit on C IV. If this absorber is collisionally ionized, the O VI/C IV limit requires T > 10^{5.3} K. For either collisional ionization or photoionization, we find that [O/H] > -2.0 at z = 0.00337.Comment: Final Ap.J. versio

    The First Detections of the Extragalactic Background Light at 3000, 5500, and 8000A (II): Measurement of Foreground Zodiacal Light

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    We present a measurement of the absolute surface brightness of the zodiacal light (3900-5100A) toward a fixed extragalactic target at high ecliptic latitude based on moderate resolution (~1.3A per pixel) spectrophotometry obtained with the du Pont 2.5m telescope at Las Campanas Observatory in Chile. This measurement and contemporaneous Hubble Space Telescope data from WFPC2 and FOS comprise a coordinated program to measure the mean flux of the diffuse extragalactic background light (EBL). The zodiacal light at optical wavelengths results from scattering by interplanetary dust, so that the zodiacal light flux toward any extragalactic target varies seasonally with the position of the Earth. This measurement of zodiacal light is therefore relevant to the specific observations (date and target field) under discussion. To obtain this result, we have developed a technique that uses the strength of the zodiacal Fraunhofer lines to identify the absolute flux of the zodiacal light in the multiple-component night sky spectrum. Statistical uncertainties in the result are 0.6% (1 sigma). However, the dominant source of uncertainty is systematic errors, which we estimate to be 1.1% (1 sigma). We discuss the contributions included in this estimate explicitly. The systematic errors in this result contribute 25% in quadrature to the final error in our coordinated EBL measurement, which is presented in the first paper of this series.Comment: Accepted for publication in ApJ, 22 pages using emulateapj.sty, version with higher resolution figures available at http://www.astro.lsa.umich.edu/~rab/publications.html or at http://nedwww.ipac.caltech.edu/level5/Sep01/Bernstein2/frames.htm

    Prospectus, November 9, 1973

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    FORD - OUR NEXT PRESIDENT?; Faculty, Staff Evaluations Adopted As College Policy; Fellowships For Women Announced; Student Senate Vice-President Resigns Post; Debaters Take Third At IVC Meet; Vandalism Suspected In Fire; Parkland To Participate In Conference; Declaration Of Impeachment; Prospectus In Perspective; Letters From Our Readers; Student Opinion Survey; President\u27s Comment; The Short Circuit; Behind The Books; Counselors And Question Marks; Zindars Shares Her Experiences; $6 Bid Tops In Vets Dance, Slave-Auction; UFO\u27s: Citizens Vs. Air Force; The Pinkertons Are At Parkland; Allied Health Program; November Student Activities Parkland College; American Assoc. Of Univ. Women Host General Meeting Nov. 11; Peterson Addresses Phi Beta Lambda; PLATO Popular With Students, Teachers; Cycle Mishap Injures One; Road Rally; Mutt and Mortie; Evening Program Diversified Next Quarter At P/C; Geology Flight Delayed; Final Exam Schedule - Fall Quarter; Costs At School Dominate P.C.A. Senate Meeting; \u27Passion Play\u27 Not Dull; P/C Gen. Biology-Pollution, Genetics Other Relevant Topics; No Grease-Monkey Graduatess At Parkland; Campus Leaders Exchange Ideas at Allerton Meeting; Parkland Co-Hosts Veterans Conference; TB Examinations; Classified Ads; A Column By And For Women: Originality, The Cell; Monday\u27s Coach; Jim Redman, Jane Hawthorne Grab Parkland\u27s First Road Rally; Football Finals To Be Held Tuesday; Fast Freddy\u27s Football Forecast; WVLJ Plans Broadcasts Of PC Basketball; Thompson Wins Fast Freddy As Upsets Abound; Local Volunteer Suggests Grants; Lost And Found; Earle, Seger Go To N.J.C.A.A. Nationals; Parkland Cagers Start Practice For Nov. 29 Debut With Millikin; Wrestlers Open Workouts, Seven Spots Open On 10-Man Roster; Parkland College Basketball Schedule 1973-74; Parkland College Wrestling Schedule 1973-74; Bowing Bulletin Board; Callboard; Changes In Calendar, Staff Status, Registration Proposed; Cade Re-elected Board Chairmanhttps://spark.parkland.edu/prospectus_1973/1002/thumbnail.jp

    Changing forest water yields in response to climate warming: results from long-term experimental watershed sites across North America

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    Climate warming is projected to affect forest water yields but the effects are expected to vary. We investigated how forest type and age affect water yield resilience to climate warming. To answer this question, we examined the variability in historical water yields at long-term experimental catchments across Canada and the United States over 5-year cool and warm periods. Using the theoretical framework of the Budyko curve, we calculated the effects of climate warming on the annual partitioning of precipitation (P) into evapotranspiration (ET) and water yield. Deviation (d) was defined as a catchment’s change in actual ET divided by P [AET/P; evaporative index (EI)] coincident with a shift from a cool to a warm period – a positive d indicates an upward shift in EI and smaller than expected water yields, and a negative d indicates a downward shift in EI and larger than expected water yields. Elasticity was defined as the ratio of inter annual variation in potential ET divided by P (PET/P; dryness index) to inter annual variation in the EI – high elasticity indicates low d despite large range in drying index (i.e., resilient water yields), low elasticity indicates high d despite small range in drying index (i.e., non-resilient water yields). Although the data needed to fully evaluate ecosystems based on these metrics are limited, we were able to identify some characteristics of response among forest types. Alpine sites showed the greatest sensitivity to climate warming with any warming leading to increased water yields. Conifer forests included catchments with lowest elasticity and stable to larger water yields. Deciduous forests included catchments with intermediate elasticity and stable to smaller water yields. Mixed coniferous/deciduous forests included catchments with highest elasticity and stable water yields. Forest type appeared to influence the resilience of catchment water yields to climate warming, with conifer and deciduous catchments more susceptible to climate warming than the more diverse mixed forest catchments

    CASA‐MIA: A ‘‘precision’’ EAS detector

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    The CASA‐MIA detector was constructed to search for sources of UHE neutral radiation. As such it has established limits well below those of previously reported observations and of most contemporaneous detectors. In addition to its primary mission, however, CASA‐MIA measures the lateral distribution of both electrons and muons in EAS throughout a range of energies and with a degree of sampling not previously available.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/87669/2/207_1.pd

    Design and operation of the Chicago air shower array

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    The Chicago Air Shower Array (CASA) is a large‐area surface scintillator array designed to study PeV sources of cosmic rays. The complete detector will consist of 1089 detector stations, distributed on a square 15 m grid. We have operated an array of 49 stations for much of the 1989 calendar year, an array of 529 stations for much of 1990, and the balance of the 1089 stations will be operating in early 1991. This surface array, together with the University of Michigan underground muon detectors (MIA), and the University of Utah atmospheric Čerenkov telescopes and Fly’s Eye air fluorescence detector, constitute a uniquely powerful instrument, dubbed the Utah Michigan Chicago (UMC) experiment, for the study of PeV sources. We report here the performance and current status of these detectors.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/87431/2/111_1.pd

    Preliminary results from the Chicago air shower array and the Michigan muon array

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    The Chicago Air Shower Array (CASA) is a large area surface array designed to detect extensive air showers (EAS) produced by primaries with energy ∼100 TeV. It operates in coincidence with the underground Michigan Muon Array (MIA). Preliminary results are presented from a search for steady emission and daily emission from three astrophysical sources: Cygnus X‐3, Hercules X‐1, and the Crab nebula and pulsar. There is no evidence for a significant signal from any of these sources in the 1989 data.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/87432/2/122_1.pd

    A search for diffuse gamma rays with energies above 1014 eV from molecular clouds in the galaxy

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    Diffuse gamma‐rays from molecular clouds are excellent tracers of cosmic rays in the galaxy over a wide range of energies. For example, diffuse emission detected by EGRET already places significant constraints on the spectrum and origin of galactic cosmic rays at GeV energies. Likewise, by measuring diffuse gamma rays with ground‐based air shower experiments, we can probe the galactic distribution of cosmic rays in the energy regime above 100 TeV.The Chicago Air Shower Array (CASA) which operates in coincidence with the Michigan muon array (MIA) is the world’s most sensitive experiment to gamma‐rays with energies ≳100 TeV, and is well‐suited for studies of diffuse sources based upon the muon content of air showers. We describe a search for diffuse gamma‐array emission from molecular cloud regions observed by CASA‐MIA. If we assume that the flux of cosmic rays is uniform in the galaxy, then we predict that diffuse emission will probably be detectable by CASA‐MIA within the lifetime of the experiment. Furthermore, if there are sources of cosmic rays in close proximity to certain molecular clouds, then the spectrum of gamma‐rays from these clouds will be stronger and harder. By searching for such enhancements in the diffuse emission, and by correlating the CASA‐MIA results with emission detected at lower energies by EGRET, we may identify or constrain the nature of cosmic rays sources in both energy regimes.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/87646/2/499_1.pd
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