bluuebunny/crossref_metadata_2025 huggingface dataset:
Introduction to the GSC MITE Point Sources project
Authors: Bonham-Carter G F
Published: March 2017

The Point Sources project of the Geological Survey of Canada's Metals in the Environment Initiative (1997 - 2002) examined the distribution of metals in various environmental sampling media around three Canadian metal smelters at Rouyn-Noranda (Quebec), Belledune
(New Brunswick), and Trail (British Columbia). This bulletin contains eleven papers on the studies made at Rouyn-Noranda and one paper on work at the Belledune smelter.

Regional surveys of snow, soil, lake sediment, peat, and vegetation were used to characterize and understand metal dispersal around the Horne smelter at Rouyn-Noranda. Metals emitted by the Horne smelter are transported by the atmosphere and radially dispersed around this point source. The resulting
smelter footprint, i.e. where metal concentrations are significantly higher than ambient background levels, shows exponentially decreasing values with increasing distance from the source in various environmental media (snow, soil, peat, lake sediment, trees). Snow data provide information about
metal loading (deposition rates) in winter conditions. The most recent growth of peat hummocks provides independent estimates of metal loading over one year. Loading data (modelled as a function of distance from the smelter) provide estimates of the total tonnage of metal deposited within (and close
to) the footprint for comparison with emission data.

The distribution of metals in marine sediments near the Brunswick lead smelter is controlled by both atmospheric and oceanographic processes. The influence of the emissions on metal levels in coastal sediments near Belledune extends at least 20 km from the smelter.
Characterization of smelter dust from the mineral fraction of humus collected around Rouyn-Noranda, Quebec
Authors: Knight R D , Henderson P J
Published: March 2017

Microbeam analyses can be used to determine the morphology, texture, size, and abundance of smelter dust trapped in humus. Smelter dust is classified into two morphotypes and five classes on the basis of texture and element associations. Size and abundance of
dusts were compiled at six sites at varied distances from the smelter. The distribution of dust reflects the geochemical signature of anthropogenic input to the humus. Notable differences in dust morphology, texture, and size suggest that part of the dust accumulation is historical and may reflect
changes in smelting practice and process through time. Particles preserved in humus represent the resistant component of smelter dust. The labile dust, observed in modern emissions, is not present.
From geological to groundwater flow models: an example of inter-operability for semi-regular grids
Authors: Ross M , Aitssi L , Martel R , Parent M
Published: March 2017

Integrating geologic information into hydrogeologic numerical models is by no means a straightforward operation. This is especially true for finite element modeling which generally requires that the geological information be integrated into grids that are
generally irregular in the horizontal (i, j) direction and regular in the vertical (k) direction. Semi-regular grids of this type are still rarely supported by geological modeling packages and the data structure can vary significantly between softwares. Nevertheless, workable solutions exist for
some software packages. Here we present a solution that allows the properties of a gOcad geomodel to be transferred to a semiregular grid built in GMS, a commonly used pre-processor for groundwater flow modeling applications. The transfer is achieved first by building in gOcad a "twin grid" that has
the same mesh structure as the original GMS grid. This is done using the research plug-in GridLab developed by the gOcad Research Group. Once the properties of the geomodel are transferred to the twin grid, cell or element number correspondences and property transfer to the original GMS grid is
achieved using the database system Access. ASCII file format is used for most data exchange between softwares. The time required to go through the procedure is on the order of minutes, even for large grids,
making it a practical solution for the lasting problem of property transfer from geological to hydrogeological models, at least until more convenient and built-in interfaces are developed.
Brine springs of northern Alberta
Authors: Grasby S E
Published: March 2017

Twenty-six brine springs discharging from Paleozoic carbonate deposits were sampled along the eastern edge of the Alberta Basin from two regions, Fort McMurray and Wood Buffalo National Park. Geochemical data indicate that the springs originate as an influx of
meteoric and glacial waters that have come into contact with, and dissolved, halite deposits. The trace metal geochemistry indicates that these
waters have interacted with carbonate rocks that have moderate to low base metal content, particularly for the Wood Buffalo region. This suggests that mineralization could be more widespread than recognized. However, there are data gaps between the national park boundary and Pine Point mine site,
where mineralization could occur.
Synthesis of Mississippi Valley-type lead-zinc deposit potential in northern Alberta and southern Northwest Territories
Authors: Hannigan P K
Published: March 2017

This paper discusses and integrates results of a research project investigating the resource potential of Mississippi Valley-type lead-zinc mineralization in northern Alberta and southern Northwest Territories. The source, flow path, and timing of fluid movement,
and the relation of these fluids to mineralization are examined.
Pre-ore isotopic signatures and fluid inclusion analyses of samples collected in Pine Point district affirm an early episode of dolomitization associated with precipitation from seawater at very shallow depths. Ore-stage carbonate deposits display numerous petrographic and diagenetic features
indicating a deeper subsurface or burial environment. Saddle dolomites and sphalerites at Pine Point display fluid inclusion-filling temperatures exceeding levels solely related to maximum burial depths of host strata beneath Paleozoic cover. Continuous recycling of magnesium-rich connate brine by
thermal convection fluid flow provides a feasible mechanism for extensive and regional development of hydrothermal dolomite and paleokarst in porous limestone overlying dense dolostone.
Context of the Deilmann orebody, Key Lake mine, Saskatchewan
Authors: Harvey S E , Bethune K M
Published: March 2017

The Deilmann orebody was formed at the intersection of the unconformity underlying Athabasca Group and an east-northeast-trending anastomosing zone of deformation centred on graphite-bearing metasedimentary rocks of the Daly Lake Group. Four ductile to
brittle-ductile deformational events predated deposition of the Athabasca Group, whereas two brittle deformational events occurred during and after deposition. Alteration and mineralization were intimately related to D5 faults, the most prominent of which is the Key Lake Fault. These formed by the
brittle reactivation of older (predating Athabasca Group) fault structures. In a paleovalley on the unconformity surface underlying the Athabasca Group, the basal Athabasca Group sandstone onlaps the erosion surface, indicating early valley-fill deposition.
Overlying strata are characterized by horizontal, laterally continuous (sheet-like) bedding. The location and pattern of mineralization suggests that this feature, in part, affected fluid flow. Near-infrared reflectance spectrometry analyses on samples from the Deilmann pit allowed identification of
a number of alteration patterns revealing a clear relationship with faults postdating the Athabasca Group. The relative abundance of these different alteration signatures is a useful exploration tool.
Sequence stratigraphy, hydrostratigraphy, and mineralizing fluid flow in the Proterozoic Manitou Falls Formation, eastern Athabasca Basin, Saskatchewan
Authors: Hiatt E E , Kyser T K
Published: March 2017

The Manitou Falls Formation, deposited during the early evolution of the eastern Athabasca Basin, is composed of flat-lying, unmetamorphosed sandstone and conglomerate that change stratigraphically upward from polymictic pebble conglomerate to medium-grained
quartz arenite. This succession has been subdivided into lithofacies that are diachronous by nature. Variations in lithofacies and
paleoenvironment are useful for lithostratigraphic correlation, but do not allow resolution of chronostratigraphic horizons.

Drill cores along two transects were studied, thickness of fluvial fining-upward successions were recorded, and these were plotted stratigraphically. Thickness of fining-upward intervals is used as a proxy for accommodation. These show systematic changes from times of low accommodation marked by
coarse-grained intervals followed by gradual shifts to greater accommodation and finer grained intervals. A hydrostratigraphic model for the eastern Athabasca Basin is presented based on integration of sedimentology, sequence stratigraphy, and diagenesis. The two basal sequences contain aquifers
that onlap basement rock units eastward and focused burial brines.
Crandallite-group minerals: host of thorium enrichment in the eastern Athabasca Basin, Saskatchewan
Authors: Mwenifumbo C J , Bernius G R
Published: March 2017

Spectral gamma-ray logs in the McArthur River area in eastern Athabasca Basin indicate anomalously high thorium content in the conglomeratic Bird Member and the lower part of the Collins Member of the Manitou Falls Formation. The distribution of Th in such
coarse-grained fluvial strata is usually associated with accessory minerals in the heavy-mineral fraction. Instead, petrographic, chemical, and
SEM analyses reported here show that Th in the Manitou Falls Formation conglomerate beds resides in a Th-rich aluminophosphate mineral. It belongs to the solid-solution series of the crandallite group, including crandallite (CaAl3(PO4)2(OH)5·H2O) and goyazite (SrAl3(PO4)2(OH)5·H2O).
Crandallite-group minerals form in highly acidic environments and are associated with clay minerals such as illite. A more extensive investigation is required to determine the relationships between the Th-rich crandallite-group phase, clay minerals, and the hydrothermal processes that operated
during the formation of uranium deposits in the Athabasca Basin.
Integrated field investigations of airborne radiometric data and drift composition, Nuclear Energy Agency - International Atomic Energy Agency Athabasca test area, Saskatchewan
Authors: Campbell J E , Klassen R A , Shives R B K
Published: March 2017

Distinctive airborne K-eU-eTh spectral associations, calibrated by ground spectrometry, define eight discrete domains. Till composition and provenance vary across the test area and vertically within glacial deposits. Till geochemistry (K, U, and Th in
<0.063 mm size fraction) differs between airborne spectral domains, but does not correlate with ground spectrometry. This likely reflects compositional differences between size fractions measured by the two methods. Linear correlations indicate that trace metals (Cu, Ni, Cr) are hosted by
HNO3-HCl-soluble Mg-bearing minerals.

The eTh-rich A1 and A2 spectral domains reflect sandstone-rich till and sandstone outcrop. The B domain on the northwest is part of a regional Quaternary glacial dispersal train of basement detritus that extends across the eastern Athabasca Basin. The D domain is curvilinear, ribbon-like, K- and
eU-rich, comprises predominantly basement-rich till with distinctive large calc-alkaline granitic boulders, and its physical-compositional characteristics cannot be explained by simple down-ice dispersal mechanisms as previously proposed.
Analyses of stresses developed in pipelines buried in freezing ground
Authors:   Geotechnical Sciences Laboratories, Carleton University
Published: March 2017

Through a joint Canada/France research project conducted at the Centre de Geomorphologie, Caen the behaviour of buried pipelines subjected to negative temperature is under investigation. Summarised in this report are the experimental results from the first and
second freeze cycles with an intervening thaw period. Among the parameters observed were the thermal regime, frost heave of the soils, pipe deformation and soil stresses . The facility tests were paralleled by laboratory testing of soil properties.
Correction of high latitude repeat station observations for disturbances
Authors: Newitt L R , Walker J K
Published: March 2017

An examination of the seasonal activity levels for a quiet year (1976) and a disturbed year (1981) using data from five Canadian observatories which form a meridional section from midlatitudes (Victoria) across the auroral zone to the polar cap (Resolute) shows
that activity is minimum in the winter. Hence, the effects of magnetic disturbance at Canadian repeat stations may be reduced by observing at this time of year . However, because of the difficulty of making observations in the winter , summer is the most feasible period for such surveys in and south
of the auroral zone; in the polar cap observations should be made as late in the summer as possible or in fall. Nevertheless there will be times when observations are made during disturbed intervals so that a means of correcting for external field effects is needed . Unfortunately, simple linear
techniques for correcting the observations at a repeat station were unsuccessful in the auroral zone, but such methods could be used in the polar cap. It is recommended that repeat station surveys in t he auroral zone be extended to a week or more in order to increase the probability of observing a
quiet interval.
Case study 9. A remote predictive mapping case study of the Boothia mainland area, Nunavut, Canada
Authors: Schetselaar E M , Ryan J
Published: March 2017

Remote predictive mapping was applied to regional-scale bedrock mapping in support of the Boothia Integrated Geoscience Project. An integrated interpretation of high-resolution airborne magnetic, Landsat TM, and legacy geological field data resulted in a
provisional geological map that was used to guide regional bedrock mapping. After the newly acquired field data were incorporated into the geoscience database, the RPM was upgraded to 1:250 000 scale geological maps in a second iteration of image interpretation and map compilation. This case study
outlines the applied RPM methodology and discusses the resulting interpretations from new insights obtained by field mapping.
The use and value of urban geology in Canada: A case study in the National Capital Region
Authors: Bélanger J R , Moore C W
Published: March 2017

In response to a request to increase its activities in environmental geology and to collaborate with the provinces, the GSC initiated a project in 1993 to provide geoscience information for urban and regional planning and development in eastern Ontario and
western Québec. Prior to the launch of the project, representatives from various levels of government, private consultants, environmentalists, universities and the general public were invited to discuss the need for and usefulness of urban geological information at a forum. The participants
confirmed the importance of urban geological information and supported a coordinating role for the GSC.

Following this forum Natural Resources Canada's Audit and Evaluation Branch undertook an impact study which examined the usefulness and value of benefits of basic types of geoscience information in urban and regional planning and development. The evaluation study of the National Capital Region
Project determined that the geoscience documents are used extensively and provide an authoritative standard for work. They are particularly useful in preliminary project planning, geotechnical engineering for major facilities, environmental impact assessments, public safety planning, and as a
multi-disciplinary research tool and field guide. The estimated value
of benefits include a 5%-20% reduction in cost of civil/environmental engineering design and planning study work, and considerable monetary savings in derived or indirect benefits amounting to annual savings of several million dollars. Recent technological advances increase the possible
range of applications especially for those who have traditionally been users of geological maps.
Canadian earthquakes - 1979
Authors: Wetmiller R J , Stevens A E , Horner R B
Published: March 2017

This catalogue lists 564 earthquakes of magnitude 3.0 or greater that occurred in Canada and adjacent areas of the United States and Greenland during 1979. The largest earthquake in this catalogue, magnitude Ms 7.1, occurred in Alaska on 28 February 21h in the
St. Elias Mountains near the southern Alaska-Yukon border. It was followed by a long series of aftershocks in Alaska and in the Yukon Territory, including about 350 of magnitude 3.0 or greater listed in this catalogue. Excluding these aftershocks, about 175 events are located in Canada or off its
coasts, including 43 of magnitude 4.0 or greater, of which 10 had magnitude 5.0 or greater. Seven of the latter occurred off the coast of British Columbia, two in the Northwest Territories and one in Québec. Except for St. Elias aftershocks, the largest earthquake in Canada, magnitude mb 5.4,
occurred on 13 March 12h west of northern Vancouver Island. Most earthquakes in 1979 occurred in the Alaska-Yukon-British Columbia border areas, off northern Vancouver Island, in the Yukon - Northwest Territories border area and in the Beaufort Sea. Minor activity continued in other seismic areas of
Canada. Induced earthquakes, confirmed or suspected, were located in several regions and were due to reservoir filling, gas and/or oil production and to potash mining. Twenty-nine earthquakes were reported felt in Canada in 1979, including nine of magnitude less than 3.0, six of them in Québec
and one each in Ontario, New Brunswick and Saskatchewan. The 20 larger felt events were reported from Québec {9), British Columbia (6), Alberta (3) and one each in the Yukon Territory and the Northwest Territories. The earthquake most widely and strongly felt in Canada occurred in Alaska on 28
February 21h along the southern Alaska-Yukon border. It was felt to distances of 700 km with maximum intensity of VII in Alaska near the epicentre, VI in the extreme south-western Yukon Territory and IV in northwestern British Columbia. The tremor caused minor property damage at several
cornrnunities along the Alaska Highway in the Yukon Territory. The other widely felt earthquake occurred in the lower St. Lawrence Valley of southern Québec on 19 August 22h. This tremor had a maximum intensity of V, was felt to distances of 150 km on average in Québec, New Brunswick and
Maine and caused some isolated chimney damage near the epicentre. The located earthquakes are listed chronologically by region in five tables following the text and plotted on seven epicentre maps. Reports of earthquakes felt in Canada in 1979 are surnrnarized in one table. Maps of intensity
distribution are presented for six of these earthquakes. Epicentral and magnitude parameters for about 1400 earthquakes smaller than magnitude 3.0 that have been located in Canada and immediately adjacent areas in 1979 are plotted on the maps and catalogued on magnetic tape with the larger events of
1979.
Investigation of pressure changes in frozen soils during thermally induced moisture migration
Authors: Williams P J , Wood J A
Published: March 2017

The report examines the application of the Clapeyron equation in describing freezing-point depression attributing freezing point depression to solute presence and to interface pressures. Mechanisms are examined by which moisture migrates through frozen soil in
bath the liquid and solid phase. In general solid phase reg-élation mechanisms appear dominant in non-coiloidal soils at marginally sub-zero temperatures whereas moisture transport dominates in colloidal soils. Preliminary pressure gradient measurements during thermally induced moisture
migration suggest a reduction in effective soil stress with a reduction in temperature.
Laboratory and Field Studies To Investigate Isotope Effects Occurring During the Formation of Permafrost - Part Iv
Authors: Michel F , Fritz P
Published: March 2017

Observations on the distribution of oxygen and hydrogen isotopes in permafrost waters have been completed at a drained lake site in the Mackenzie Delta, along the Dempster Highway, Additional laboratory observations of isotope 'fractionation in phase change were
completed. The analyses are used in conjunction with c14 dates to delineate the history of the drained lake basin over the past 9000 yrs. and to examine permafrost history and the origin of the waters in the northeastern Yukon.
Investigation of moisture movements and stresses in frozen soils
Authors: Williams P J , Wood J A
Published: March 2017

Long term permeameter results are reported for Allendale and and Castor soils at marginally sub-zero temperatures and temperature gradients of 0.17°c cm-l The flow regime is interpreted in terms of soil stress and the Clapeyron
equation.
Extraction and compilation of available temperature and snow-fall sata in the Ungava Peninsula as input to geothermal modelling of Quaternary Paleoclimates
Authors: Gray J T
Published: March 2017

This report presents information on recent air and ground temperature, snowfall, snow cover amounts and duration from as many locations as possible for the Ungava Penninsula. It is presented in the form of tables, diagrams and maps with an accompanying
interpretative text .
General state of the art review of ground probing radar
Authors:   A-Cubed Inc.
Published: March 2017

This document summarizes the current state-of-the-art in the field of ground probing radar. Ground probing radar (GPR) is a relatively unique area of geophysical endeavour in which high frequency radio frequency signals are utilized to map structure beneath the
earth's surface. The methods, applications and instrumentation in this field have sprung up over the last 10 to 15 years. It is, therefore, very timely that a general review of the current state of the industry and research in this field be carried out .
Preliminary Results of Shallow Drilling in the Garibaldi Volcanic Belt, British Columbia, 1982
Authors: Bentkowski W H , Lewis T J
Published: March 2017

Fifteen shallow (100 m) boreholes have been drilled within the Coast Plutonic Complex surrounding the Garibaldi Volcanic Belt to provide regional heat flow data in order to better understand the overall thermal regime. The holes are located in the Squamish and
Elaho River valleys 65 to 80 km north of Squamish, and in the Ryan River and Railroad Creek valleys 20 to 40 km northwest of Pemberton. A casing and grouting technique was used for hole completion to prevent axial water flow and to ensure subsequent access for temperature mesurements. Geothermal
gradients range from 15.8 to 61.0 mK.m-1 Water movement around or beneath the holes due to the rugged topography is assumed to be present where the gradient varies significantly within individual holes. Heat generation within the intrusive rocks is .57 ?Wm -3 , consistent with average values for
the Coast Plutonic Complex.
Canadian earthquakes - 1983
Authors: Drysdale J A , Horner R B
Published: March 2017

During 1983, 293 earthquakes of magnitude 3.0 or greater occurred in Canada and adjacent areas of the United States and Greenland. These are listed chronologically by region in five tables following the text. Epicentral and magnitude parameters have been
determined for 823 earthquakes smaller than magnitude 3.0 in or near Canada in 1983 and are plotted along with the larger events on seven epicentre maps. All events are catalogued on magnetic tape and are available upon request. Earthquake activity occurred primarily in the recognized zones of past
seismicity. A total of 32 earthquake s were felt in Canada including six less than magnitude 3 . 0 . The most significant activity in eastern Canada occurred in southern Ontario and western Quebec during October and early November when five earthquakes were felt . Brief details of these events are:
04 October, 3.1 mN, in Burlington, Ontario; 07 October, 5.1 mb, near Blue Mountain Lake in New York State; 11 October, 4 .1 mN, south of Ottawa, Ontario near North Gower; 16 October, 3.1 mN, east of Ottawa, Ontario near Rockland; and 01 November, 3 .4 mN, near Montreal, Quebec . The New York State
(Goodnow) earthquake is the largest from that area since the 05 September 1944 magnitude 5 . 7 Cornwall earthquake. The strongest and most widely felt event affecting western Canada occurred on 28 October near Borah Peak, Idaho. In Canada it was felt throughout southern British Columbia, southern
Alberta and southwestern Saskatchewan. The two largest earthquakes in western Canada occurred on 06 April, 5 .1 mb and on 31 July, 5.0 ML and were located off the northwestern coast of the Queen Charlotte Islands. In the southwestern Yukon Territory a 5.4 mb earthquake on 30 March was felt to
distances of 300 km. The largest and only felt event in northern Canada outside the southern Yukon took place near Dawson on 05 October, 4.6 ML.
IGNITION SWITCH
Authors:   Circuit Protection and Switch Device Committee
Published: March 2017
Optical and geometrical properties of cirrus clouds in Amazonia derived from 1 year of ground-based lidar measurements
Authors: Gouveia Diego A. , Barja Boris , Barbosa Henrique M. J. , Seifert Patric , Baars Holger , Pauliquevis Theotonio , Artaxo Paulo
Published: March 2017

Abstract. Cirrus clouds cover a large fraction of tropical latitudes and play an important role in Earth's radiation budget. Their optical properties, altitude, vertical and horizontal coverage control their radiative forcing, and hence detailed cirrus measurements at different geographical locations are of utmost importance. Studies reporting cirrus properties over tropical rain forests like the Amazon, however, are scarce. Studies with satellite profilers do not give information on the diurnal cycle, and the satellite imagers do not report on the cloud vertical structure. At the same time, ground-based lidar studies are restricted to a few case studies. In this paper, we derive the first comprehensive statistics of optical and geometrical properties of upper-tropospheric cirrus clouds in Amazonia. We used 1 year (July 2011 to June 2012) of ground-based lidar atmospheric observations north of Manaus, Brazil. This dataset was processed by an automatic cloud detection and optical properties retrieval algorithm. Upper-tropospheric cirrus clouds were observed more frequently than reported previously for tropical regions. The frequency of occurrence was found to be as high as 88 % during the wet season and not lower than 50 % during the dry season. The diurnal cycle shows a minimum around local noon and maximum during late afternoon, associated with the diurnal cycle of precipitation. The mean values of cirrus cloud top and base heights, cloud thickness, and cloud optical depth were 14.3 ± 1.9 (SD) km, 12.9 ± 2.2 km, 1.4 ± 1.1 km, and 0.25 ± 0.46, respectively. Cirrus clouds were found at temperatures down to −90 °C. Frequently cirrus were observed within the tropical tropopause layer (TTL), which are likely associated to slow mesoscale uplifting or to the remnants of overshooting convection. The vertical distribution was not uniform, and thin and subvisible cirrus occurred more frequently closer to the tropopause. The mean lidar ratio was 23.3 ± 8.0 sr. However, for subvisible cirrus clouds a bimodal distribution with a secondary peak at about 44 sr was found suggesting a mixed composition. A dependence of the lidar ratio with cloud temperature (altitude) was not found, indicating that the clouds are vertically well mixed. The frequency of occurrence of cirrus clouds classified as subvisible (τ < 0. 03) were 41.6 %, whilst 37.8 % were thin cirrus (0. 03 < τ < 0. 3) and 20.5 % opaque cirrus (τ > 0. 3). Hence, in central Amazonia not only a high frequency of cirrus clouds occurs, but also a large fraction of subvisible cirrus clouds. This high frequency of subvisible cirrus clouds may contaminate aerosol optical depth measured by sun photometers and satellite sensors to an unknown extent.
Contribution of feldspar and marine organic aerosols to global ice nucleating particle concentrations
Authors: Vergara-Temprado Jesús , Murray Benjamin J. , Wilson Theodore W. , O'Sullivan Daniel , Browse Jo , Pringle Kirsty J. , Ardon-Dryer Karin , Bertram Allan K. , Burrows Susannah M. , Ceburnis Darius , DeMott Paul J. , Mason Ryan H. , O'Dowd Colin D. , Rinaldi Matteo , Carslaw Ken S.
Published: March 2017

Abstract. Ice-nucleating particles (INPs) are known to affect the amount of ice in mixed-phase clouds, thereby influencing many of their properties. The atmospheric INP concentration changes by orders of magnitude from terrestrial to marine environments, which typically contain much lower concentrations. Many modelling studies use parameterizations for heterogeneous ice nucleation and cloud ice processes that do not account for this difference because they were developed based on INP measurements made predominantly in terrestrial environments without considering the aerosol composition. Errors in the assumed INP concentration will influence the simulated amount of ice in mixed-phase clouds, leading to errors in top-of-atmosphere radiative flux and ultimately the climate sensitivity of the model. Here we develop a global model of INP concentrations relevant for mixed-phase clouds based on laboratory and field measurements of ice nucleation by K-feldspar (an ice-active component of desert dust) and marine organic aerosols (from sea spray). The simulated global distribution of INP concentrations based on these two species agrees much better with currently available ambient measurements than when INP concentrations are assumed to depend only on temperature or particle size. Underestimation of INP concentrations in some terrestrial locations may be due to the neglect of INPs from other terrestrial sources. Our model indicates that, on a monthly average basis, desert dusts dominate the contribution to the INP population over much of the world, but marine organics become increasingly important over remote oceans and they dominate over the Southern Ocean. However, day-to-day variability is important. Because desert dust aerosol tends to be sporadic, marine organic aerosols dominate the INP population on many days per month over much of the mid- and high-latitude Northern Hemisphere. This study advances our understanding of which aerosol species need to be included in order to adequately describe the global and regional distribution of INPs in models, which will guide ice nucleation researchers on where to focus future laboratory and field work.
Changes in the domestic heating fuel in Greece: effects on atmospheric chemistry and radiation
Authors: Athanasopoulou Eleni , Speyer Orestis , Brunner Dominik , Vogel Heike , Vogel Bernhard , Mihalopoulos Nikolaos , Gerasopoulos Evangelos
Published: March 2017

Abstract. For the past 8 years, Greece has been experiencing a major financial crisis which, among other side effects, led to a shift in the fuel used for residential heating from fossil fuel towards bio-fuels, primarily wood. This study simulates the fate of the residential wood burning aerosol plume (RWB smog) and implications on atmospheric chemistry and radiation, with the support of detailed aerosol characterization from measurements during the winter 2013–2014 in Athens. The applied model system (TNO-MACC_II emissions/COSMO-ART model) and configuration used, accurately predicts the frequent nighttime aerosol spikes (hourly PM10 > 75 μg m−3) and their chemical profile (carbonaceous components and ratios). Updated temporal and chemical RWB emission profiles, derived from measurements, were used, while the level of model performance was tested for different heating demand conditions, resulting to better agreement with measurements for Tmin
Illustration of microphysical processes in Amazonian deep convective clouds in the Gamma phase space: Introduction and potential applications
Authors: Cecchini Micael A. , Machado Luiz A. T. , Wendisch Manfred , Costa Anja , Krämer Martina , Andreae Meinrat O. , Afchine Armin , Albrecht Rachel I. , Artaxo Paulo , Borrmann Stepahn , Fütterer Daniel , Klimach Thomas , Mahnke Christoph , Martin Scot T. , Minikin Andreas , Molleker Sergej , Pardo Lianet H. , Pöhlker Christopher , Pöhlker Mira L. , Pöschl Ulrich , Rosenfeld Daniel , Weinzierl Bernadett
Published: March 2017

Abstract. The behavior of tropical clouds remains a major open scientific question, given that the associated phys-ics is not well represented by models. One challenge is to realistically reproduce cloud droplet size dis-tributions (DSD) and their evolution over time and space. Many applications, not limited to models, use the Gamma function to represent DSDs. However, there is almost no study dedicated to understanding the phase space of this function, which is given by the three parameters that define the DSD intercept, shape, and curvature. Gamma phase space may provide a common framework for parameterizations and inter-comparisons. Here, we introduce the phase-space approach and its characteristics, focusing on warm-phase microphysical cloud properties and the transition to the mixed-phase layer. We show that trajectories in this phase space can represent DSD evolution and can be related to growth processes. Condensational and collisional growth may be interpreted as pseudo-forces that induce displacements in opposite directions within the phase space. The actually observed movements in the phase space are a result of the combination of such pseudo-forces. Additionally, aerosol effects can be evaluated given their significant impact on DSDs. The DSDs associated with liquid droplets that favor cloud glaciation can be delimited in the phase space, which can help models to adequately predict the transition to the mixed phase. We also consider possible ways to constrain the DSD in two-moment bulk microphysics schemes, where the relative dispersion parameter of the DSD can play a significant role. Overall, the Gamma phase-space approach can be an invaluable tool for studying cloud microphysical evolution and can be readily applied in many scenarios that rely on Gamma DSDs.
Human amplified changes in precipitation-runoff patterns in large
river basins of the Midwestern United States
Authors: Kelly Sara A. , Takbiri Zeinab , Belmont Patrick , Foufoula-Georgiou Efi
Published: March 2017

Abstract. Complete transformations of land cover from prairie, wetlands, and hardwood forests to row crop agriculture and urban centers are thought to have caused profound changes in hydrology in the Upper Midwestern US since the 1800s. In this study, we investigate four large (23,000–69,000 km2) Midwest river basins that span climate and land use gradients to understand how climate and agricultural drainage have influenced basin hydrology over the last 79 years. We use daily, monthly, and annual flow metrics to document streamflow changes and discuss those changes in the context of precipitation and land use changes. Since 1935, flow, precipitation, artificial drainage extent, and corn and soybean acreage have increased across the region. In extensively drained basins, we observe 2 to 4 fold increases in low flows and 1.5 to 3 fold increases in high and extreme flows. Using a water budget, we determined that the storage term has decreased in intensively drained and cultivated basins by 30 %–200 % since 1975, but increased by roughly 30 % in the less agricultural basin. Storage has generally decreased during spring and summer months and increased during fall and winter months in all watersheds. Thus, the loss of storage and enhanced hydrologic connectivity and efficiency imparted by artificial agricultural drainage appear to have amplified the streamflow response to precipitation increases in the Midwest. Future increases in precipitation are likely to further intensify drainage practices and increase streamflows. Increased streamflow has implications for flood risk, channel adjustment, and sediment and nutrient transport and presents unique challenges for agriculture and water resource management in the Midwest. Better documentation of existing and future drain tile and ditch installation is needed to further understand the role of climate versus drainage across multiple spatial and temporal scales.
Micro-scale and nano-scale strain mapping techniques applied to creep of rocks
Authors: Quintanilla-Terminel Alejandra , Zimmerman Mark , Evans Brian , Kohlstedt David
Published: March 2017

Abstract. Usually, several deformation mechanisms interact to accommodate plastic deformation. Quantifying the contribution of each to the total strain is necessary to bridge from observations of microstructures to geomechanical descriptions and, thus, is a critical component in the extrapolation from laboratory data to field observations. Here, we describe experimental and computational techniques involved in micro-scale strain mapping (MSSM), which allows strain produced during high-pressure, high-temperature deformation experiments to be tracked with high resolution. MSSM relies on the analysis of relative displacement of initially regularly spaced markers after deformation. We present two lithography techniques used to pattern rock substrates at different scales: photolithography and electron-beam lithography. Further, we discuss the challenges of applying the MSSM technique to samples used in high-temperature and pressure experiments. We applied the MSSM technique to a study of strain partitioning during creep of Carrara marble and grain boundary sliding in San Carlos olivine, synthetic forsterite, and Solnhofen limestone at a confining pressure, Pc, of 300 MPa and homologous temperatures, T/Tm, of 0.3 to 0.6. The MSSM technique works very well up to temperatures of 700 ºC. Experimental developments described here show promising results for higher temperature applications.
Drug eluting grafts for hemodialysis access
Authors: Glickman Marc
Published: March 2017

The development of new methods for drug elution of graft material, biofiber films and resurfacing of prosthetic graft surfaces offers new opportunities for improvement of graft function in arteriovenous (AV) access. Three areas of research include developing grafts that reduce the development of neointimal hyperplasia, reducing infection and reducing thrombogenicity. The only drug eluting graft presently being used, is the heparin coated expanded polytetrafluoroethylene (ePTFE) graft, which has been shown to decrease the incidence of early thrombosis. New drug eluting grafts include those with paclitaxel and those with antibiotics. The development of a hybrid coated prosthetic graft that can deliver targeted gene therapies holds great promise in the field.
Patient-related factors influencing patency of autogenous brachiocephalic haemodialysis fistulas
Authors: Lamprou Alexander , de Bruin Cor , van Roon Arie , Loonstra Jan , van der Laan Maarten , Tielliu Ignace , Zeebregts Clark
Published: March 2017

Objective

The objective of this study was to analyse the outcome of autogenous brachiocephalic fistula for dialysis purposes and to determine modifiable and non-modifiable patient-related factors of influence on the patency of a newly created fistula.

Design of study

A single-centre retrospective cohort study with the aim of determining patient-related factors of influence on primary failure, primary, primary assisted and secondary patency of autogenous brachiocephalic fistulas. Seventeen patient-related variables were determined by means of univariate analysis, variables reaching significance were then entered in a multivariate Cox-regression model.

Results

Between October 2005-October 2015, 231 autogenous brachiocephalic fistulas were created in 228 patients. Mean age was 61.3 years (20.3-88.2 years). Patency was calculated using Kaplan-Meier analysis. Primary failure occurred in 38 out of 231 created fistulas (16.5%). The primary, primary assisted and secondary patency rates at six months were 78 ± 3%, 93 ± 2%, and 95 ± 1%, respectively. At 12 months, they were 63 ± 3%, 89 ± 2%, and 92 ± 2%, and at 24 months 47 ± 4%, 84 ± 3%, and 89 ± 2%. The non-modifiable factors, diabetes mellitus and mean cephalic vein diameter were identified as a predictor for failure influencing primary and secondary patency. The preoperative use of anticoagulation was identified as a modifiable factor for failure.

Conclusions

This study identified several non-modifiable and modifiable factors of interest to the clinician deciding on which type of haemodialysis fistula is most suitable for an individual patient. Meticulous preoperative work-up, a surveillance programme, and a dedicated multidisciplinary team can be of great importance in achieving better patency rates.
Endovascular treatment to boost AV fistula maturation
Authors: Kamper Lars , Haage Patrick
Published: March 2017

Impaired fistula maturation is associated with puncture-related complications, insufficient dialysis and potential permanent access failure. Non-maturation is frequently initiated by stenotic vascular access vessels comprising the outflow veins, the arteriovenous anastomosis and infrequently the inflow artery. Further findings in maturation protraction are central venous stenoses or accessory outflow veins. Depending on the underlying pathology, several endovascular approaches to boost fistula maturation are possible. To date standard balloon angioplasty remains the primary proven treatment option.
Dialysis-associated steal syndrome (DASS)
Authors: Mohamed Ahmed S. , Peden Eric K.
Published: March 2017

Introduction

In this article, we will review the clinical symptoms of dialysis access steal syndrome (DASS), evaluation, treatment options, and our approach and treatment algorithm.

Methods

We reviewed the literature discussing different aspects of DASS including its epidemiology, pathogenesis, clinical presentation, evaluation and management options.

Results

DASS is the most dreaded complication of access surgery. Although the incidence is low, all providers caring for dialysis patients should be aware of this problem. Symptoms can range from mild to limb threatening. Although various tests are available, the diagnosis of DASS remains a clinical one and requires thoughtful management to have the best outcomes.

Conclusions

Multiple treatment options exist for steal. We present diagnostic evaluation and management algorithm.
Optimal timing for vascular access creation
Authors: Jemcov Tamara K. , Van Biesen Wim
Published: March 2017

Many guidelines recommend that end-stage renal disease (ESRD) patients should have a permanent vascular access, preferably an autologous arteriovenous fistula (AVF), at the start of renal replacement therapy. Nevertheless, a large proportion of patients still start hemodialysis with a central venous catheter (CVC). On the other hand, there are increasing numbers of patients in whom an AVF has been created, but who never actually end up on dialysis, as well as a substantial number of patients in whom creation of a vascular access has been attempted unsuccessfully.

To improve this situation, timely exploration to assess suitability for and creation of preemptive AVF should be promoted. Decision to construct an AVF should depend on the likelihood and rate of progression to ESRD. For this goal, some reliable prediction models are available. Also, the likelihood that such an attempt will result in a successful outcome should be taken into account, but suitable validated models to accurately make such estimates are lacking. Next to patient-specific factors, some local conditions such as easy access to a vascular surgeon should also be incorporated in the decision-making process between the nephrology team and the patient.
Is shear stress the key factor for AVF maturation?
Authors: Remuzzi Andrea , Bozzetto Michela , Brambilla Paolo
Published: March 2017

Autologous arteriovenous fistula (AVF) is the preferred choice for providing vascular access to hemodialysis (HD) patients, but it is still affected by high incidence of non-maturation or early failure. After creation, AVF must undergo vascular remodeling, a process characterized by an increase in blood vessel diameter and wall thickness, to allow efficient and adequate HD. A growing body of evidence indicates that AVF maturation is related to the response of endothelial cells (ECs) to changes in wall shear stress (WSS), and in particular, to changes of its peak value. The reasons why important number of AVFs are affected by non-maturation or early failure still remain to be elucidated, but it has been suggested that local hemodynamic conditions with highly disturbed flow patterns may play an important role. In the present contribution, we addressed the role of WSS on AVF maturation, clarifying mechanisms that affect the clinical outcome of AVF creation. We also pointed out the need of non-invasive longitudinal studies, with repeated observations of hemodynamic parameters and structural changes during time, to obtain evidence of a cause-and-effect relationship between the presence of disturbed flow and AVF maturation failure. This understanding may be fundamental in the future to ameliorate clinical outcome of AVF creation, with a great impact on the clinical management of HD patients and their quality of life.
Forearm versus upper arm grafts for vascular access
Authors: Gage Shawn M. , Lawson Jeffrey H.
Published: March 2017

Forearm and upper arm arteriovenous grafts perform similarly in terms of patency and complications. Primary patency at 1 year for forearm arteriovenous grafts versus upper arm grafts ranges from 22%-50% versus 22%-42%, and secondary patency at 1 year ranges from 78%-89% versus 52%-67%), respectively. Secondary patency at 2 years, ranges from 30%-64% versus 35%-60% for forearm and upper arteriovenous graft, respectively. Ample pre-operative planning is essential to improved clinical success and the decision to place a graft at one location versus the other should be based solely on previous access history, physical exam, appropriate venous imaging, and other factors that make up the clinical picture. Operative implant strategies and risk of complications are very similar between the two configurations. Postoperative ischemia due to steal syndrome is a potential complication that requires immediate attention. Utilization of the proximal radial or ulnar artery for inflow for the graft can minimize risk of clinically relevant steal syndrome.
Bioengineered hemodialysis access grafts
Authors: Gage Shawn M. , Lawson Jeffrey H.
Published: March 2017

There is a need for bioengineered therapies to improve the overall health of the growing and aging world population. Patients with renal failure have a life-long requirement for a durable form of hemodialysis vascular access. In this article, we review the history of tissue engineering as it pertains to bioengineered grafts and vessels for hemodialysis access. Over the years, various strategies have been utilized to develop ideal, humanized vessels for vascular replacement such as fixation of animal or human vessels, cell seeding of synthetic materials, and the synthesis of completely autologous or allogeneic bioengineered vessels. Tissue engineering technologies from two companies have progressed to reach phase 2 and phase 3 clinical trials, but the prospect of newer strategies on the horizon may offer improved manufacturing efficiency, a greater variety of conduit size and length, and reduce the cost to produce.