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  1. Article ; Online: Extreme shifts in pyrite sulfur isotope compositions reveal the path to bonanza gold.

    McLeish, Duncan F / Williams-Jones, Anthony E / Clark, James R / Stern, Richard A

    Proceedings of the National Academy of Sciences of the United States of America

    2024  Volume 121, Issue 21, Page(s) e2402116121

    Abstract: Pyrite is the most common sulfide mineral in hydrothermal ore-forming systems. The ubiquity and abundance of pyrite, combined with its ability to record and preserve a history of fluid evolution in crustal environments, make it an ideal mineral for ... ...

    Abstract Pyrite is the most common sulfide mineral in hydrothermal ore-forming systems. The ubiquity and abundance of pyrite, combined with its ability to record and preserve a history of fluid evolution in crustal environments, make it an ideal mineral for studying the genesis of hydrothermal ore deposits, including those that host critical metals. However, with the exception of boiling, few studies have been able to directly link changes in pyrite chemistry to the processes responsible for bonanza-style gold mineralization. Here, we report the results of high-resolution secondary-ion mass spectrometry and electron microprobe analyses conducted on pyrite from the Brucejack epithermal gold deposit, British Columbia. Our δ
    Language English
    Publishing date 2024-05-13
    Publishing country United States
    Document type Journal Article
    ZDB-ID 209104-5
    ISSN 1091-6490 ; 0027-8424
    ISSN (online) 1091-6490
    ISSN 0027-8424
    DOI 10.1073/pnas.2402116121
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  2. Article ; Online: Assessing the Likelihood of Failure Due to Stem Decay Using Different Assessment Techniques

    Okun, Ari / Brazee, Nicholas J. / Clark, James R. / Cunningham-Minnick, Michael J. / Burcham, Daniel C. / Kane, Brian

    Forests. 2023 May 18, v. 14, no. 5

    2023  

    Abstract: Arborists commonly investigate the extent of stem decay to assess the likelihood of stem failure when conducting tree risk assessments. Studies have shown that: (i) arborists can sometimes judge the extent of internal decay based on external signs; (ii) ... ...

    Abstract Arborists commonly investigate the extent of stem decay to assess the likelihood of stem failure when conducting tree risk assessments. Studies have shown that: (i) arborists can sometimes judge the extent of internal decay based on external signs; (ii) sophisticated tools can reliably illustrate the extent of internal decay; and (iii) assessing components of tree risk can be highly subjective. We recruited 18 experienced tree risk assessors who held the International Society of Arboriculture’s Tree Risk Assessment Qualification (TRAQ) to assess the likelihood of stem failure due to decay after each of five consecutive assessments on 30 individuals of 2 genera. The five assessment techniques, in stepwise order, were: (1) observing visually, (2) sounding the trunk with a mallet, (3) viewing a scaled diagram of the cross-section that revealed sound and decayed wood ascertained from resistance drilling, (4) viewing sonic and electrical resistance tomograms, and (5) consulting with a peer. For each technique, the assessors assigned two or more likelihood of failure ratings (LoFRs) for at least 83% of trees, which were proportionally greatest after the assessors viewed the tomograms; the proportions did not differ among the other four assessment techniques. Covariates that influenced the distribution of the LoFRs included percent of the cross-section that was decayed, and assessors’ experience using resistance drilling devices and tomography in regular practice. Practitioners should be aware that disagreement on the likelihood of tree failure exists even among experienced arborists.
    Keywords arboriculture ; arborists ; decayed wood ; electrical resistance ; risk ; risk assessment ; tomography ; trees
    Language English
    Dates of publication 2023-0518
    Publishing place Multidisciplinary Digital Publishing Institute
    Document type Article ; Online
    ZDB-ID 2527081-3
    ISSN 1999-4907
    ISSN 1999-4907
    DOI 10.3390/f14051043
    Database NAL-Catalogue (AGRICOLA)

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  3. Article: Identifying and protecting macroalgae detritus sinks toward climate change mitigation.

    Queirós, Ana M / Tait, Karen / Clark, James R / Bedington, Michel / Pascoe, Christine / Torres, Ricardo / Somerfield, Paul J / Smale, Dan A

    Ecological applications : a publication of the Ecological Society of America

    2023  Volume 33, Issue 3, Page(s) e2798

    Abstract: Harnessing natural solutions to mitigate climate change requires an understanding of carbon fixation, flux, and sequestration across ocean habitats. Recent studies have suggested that exported seaweed particulate organic carbon is stored within soft- ... ...

    Abstract Harnessing natural solutions to mitigate climate change requires an understanding of carbon fixation, flux, and sequestration across ocean habitats. Recent studies have suggested that exported seaweed particulate organic carbon is stored within soft-sediment systems. However, very little is known about how seaweed detritus disperses from coastlines, or where it may enter seabed carbon stores, where it could become the target of conservation efforts. Here, focusing on regionally dominant seaweed species, we surveyed environmental DNA (eDNA) from natural coastal sediments, and studied their connectivity to seaweed habitats using a particle tracking model parameterized to reproduce seaweed detritus dispersal behavior based on laboratory observations of seaweed fragment degradation and sinking. Experiments showed that seaweed detritus density changed over time, differently across species. This, in turn, modified distances traveled by released fragments until they reached the seabed for the first time, during model simulations. Dispersal pathways connected detritus from the shore to the open ocean but, importantly, also to coastal sediments, and this was reflected by field eDNA evidence. Dispersion pathways were also affected by hydrodynamic conditions, varying in space and time. Both the properties and timing of released detritus, individual to each macroalgal population, and short-term near-seabed and medium-term water-column transport pathways, are thus seemingly important in determining the connectivity between seaweed habitats and potential sedimentary sinks. Studies such as this one, supported by further field verification of sedimentary carbon sequestration rates and source partitioning, are still needed to help quantify the role of seaweed in the ocean carbon cycle. Such studies will provide vital evidence to inform on the potential need to develop blue carbon conservation mechanisms, beyond wetlands.
    MeSH term(s) Seaweed/metabolism ; Climate Change ; Ecosystem ; Wetlands ; Carbon/metabolism
    Chemical Substances Carbon (7440-44-0)
    Language English
    Publishing date 2023-02-14
    Publishing country United States
    Document type Journal Article ; Research Support, Non-U.S. Gov't
    ZDB-ID 1074505-1
    ISSN 1939-5582 ; 1051-0761
    ISSN (online) 1939-5582
    ISSN 1051-0761
    DOI 10.1002/eap.2798
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    In stock of ZB MED Bonn / Germany

    Z 5240: Show issues

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  4. Article ; Online: Identifying and protecting macroalgae detritus sinks toward climate change mitigation

    Queirós, Ana M. / Tait, Karen / Clark, James R. / Bedington, Michel / Pascoe, Christine / Torres, Ricardo / Somerfield, Paul J. / Smale, Dan A.

    Ecological Applications. 2023 Apr., v. 33, no. 3 p.e2798-

    2023  

    Abstract: Harnessing natural solutions to mitigate climate change requires an understanding of carbon fixation, flux, and sequestration across ocean habitats. Recent studies have suggested that exported seaweed particulate organic carbon is stored within soft‐ ... ...

    Abstract Harnessing natural solutions to mitigate climate change requires an understanding of carbon fixation, flux, and sequestration across ocean habitats. Recent studies have suggested that exported seaweed particulate organic carbon is stored within soft‐sediment systems. However, very little is known about how seaweed detritus disperses from coastlines, or where it may enter seabed carbon stores, where it could become the target of conservation efforts. Here, focusing on regionally dominant seaweed species, we surveyed environmental DNA (eDNA) from natural coastal sediments, and studied their connectivity to seaweed habitats using a particle tracking model parameterized to reproduce seaweed detritus dispersal behavior based on laboratory observations of seaweed fragment degradation and sinking. Experiments showed that seaweed detritus density changed over time, differently across species. This, in turn, modified distances traveled by released fragments until they reached the seabed for the first time, during model simulations. Dispersal pathways connected detritus from the shore to the open ocean but, importantly, also to coastal sediments, and this was reflected by field eDNA evidence. Dispersion pathways were also affected by hydrodynamic conditions, varying in space and time. Both the properties and timing of released detritus, individual to each macroalgal population, and short‐term near‐seabed and medium‐term water‐column transport pathways, are thus seemingly important in determining the connectivity between seaweed habitats and potential sedimentary sinks. Studies such as this one, supported by further field verification of sedimentary carbon sequestration rates and source partitioning, are still needed to help quantify the role of seaweed in the ocean carbon cycle. Such studies will provide vital evidence to inform on the potential need to develop blue carbon conservation mechanisms, beyond wetlands.
    Keywords blue carbon ; carbon dioxide fixation ; carbon sequestration ; climate change ; detritus ; dispersal behavior ; environmental DNA ; hydrodynamics ; macroalgae ; models ; particulate organic carbon ; space and time
    Language English
    Dates of publication 2023-04
    Publishing place John Wiley & Sons, Inc.
    Document type Article ; Online
    Note JOURNAL ARTICLE
    ZDB-ID 1074505-1
    ISSN 1939-5582 ; 1051-0761
    ISSN (online) 1939-5582
    ISSN 1051-0761
    DOI 10.1002/eap.2798
    Database NAL-Catalogue (AGRICOLA)

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  5. Article ; Online: Identifying potential high-risk zones for land-derived plastic litter to marine megafauna and key habitats within the North Atlantic.

    Garrard, Samantha L / Clark, James R / Martin, Nicola / Nelms, Sarah E / Botterell, Zara L R / Cole, Matthew / Coppock, Rachel L / Galloway, Tamara S / Green, Dannielle S / Jones, Megan / Lindeque, Pennie K / Tillin, Heidi M / Beaumont, Nicola J

    The Science of the total environment

    2024  Volume 922, Page(s) 171282

    Abstract: The pervasive use of plastic in modern society has led to plastic litter becoming ubiquitous within the ocean. Land-based sources of plastic litter are thought to account for the majority of plastic pollution in the marine environment, with plastic bags, ...

    Abstract The pervasive use of plastic in modern society has led to plastic litter becoming ubiquitous within the ocean. Land-based sources of plastic litter are thought to account for the majority of plastic pollution in the marine environment, with plastic bags, bottles, wrappers, food containers and cutlery among the most common items found. In the marine environment, plastic is a transboundary pollutant, with the potential to cause damage far beyond the political borders from where it originated, making the management of this global pollutant particularly complex. In this study, the risks of land-derived plastic litter (LDPL) to major groups of marine megafauna - seabirds, cetaceans, pinnipeds, elasmobranchs, turtles, sirenians, tuna and billfish - and a selection of productive and biodiverse biogenic habitats - coral reefs, mangroves, seagrass, saltmarsh and kelp beds - were analysed using a Spatial Risk Assessment approach. The approach combines metrics for vulnerability (mechanism of harm for megafauna group or habitat), hazard (plastic abundance) and exposure (distribution of group or habitat). Several potential high-risk zones (HRZs) across the North Atlantic were highlighted, including the Azores, the UK, the French and US Atlantic coasts, and the US Gulf of Mexico. Whilst much of the modelled LDPL driving risk in the UK originated from domestic sources, in other HRZs, such as the Azores archipelago and the US Gulf of Mexico, plastic originated almost exclusively from external (non-domestic) sources. LDPL from Caribbean islands - some of the largest generators of marine plastic pollution in the dataset of river plastic emissions used in the study - was noted as a significant input to HRZs across both sides of the Atlantic. These findings highlight the potential of Spatial Risk Assessment analyses to determine the location of HRZs and understand where plastic debris monitoring and management should be prioritised, enabling more efficient deployment of interventions and mitigation measures.
    MeSH term(s) Environmental Monitoring ; Plastics ; Ecosystem ; Environmental Pollution ; Environmental Pollutants ; Waste Products/analysis
    Chemical Substances Plastics ; Environmental Pollutants ; Waste Products
    Language English
    Publishing date 2024-02-25
    Publishing country Netherlands
    Document type Journal Article
    ZDB-ID 121506-1
    ISSN 1879-1026 ; 0048-9697
    ISSN (online) 1879-1026
    ISSN 0048-9697
    DOI 10.1016/j.scitotenv.2024.171282
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    Zs.A 949: Show issues Location:
    Je nach Verfügbarkeit (siehe Angabe bei Bestand)
    bis Jg. 1994: Bestellungen von Artikeln über das Online-Bestellformular
    Jg. 1995 - 2021: Lesesall (1.OG)
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  6. Book: A handbook of hazard tree evaluation for utility arborists

    Clark, James R. / Matheny, Nelda P.

    1993  

    Author's details James R. Clark ; Nelda P. Matheny
    Size 34 S. : graph. Darst.
    Publisher Internat. Soc. of Arboriculture
    Publishing place Savoy, IL
    Publishing country United States
    Document type Book
    HBZ-ID HT007563926
    ISBN 1-881956-05-9 ; 978-1-881956-05-1
    Database Catalogue ZB MED Nutrition, Environment, Agriculture

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    Shelf markLoan statusLocation
    978/1721 available for loan (reading room) Freihandmagazin (U1)

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  7. Article ; Online: The acute effects of exercise intensity and inorganic nitrate supplementation on vascular health in females after menopause.

    Hogwood, Austin C / Ortiz de Zevallos, Joaquin / Weeldreyer, Nathan / Clark, James R / Mazzella, Vincent / Cain, Lauren / Myaing, Dylan / Love, Kaitlin M / Weltman, Arthur / Allen, Jason D

    Journal of applied physiology (Bethesda, Md. : 1985)

    2023  Volume 135, Issue 5, Page(s) 1070–1081

    Abstract: Menopause is associated with reduced nitric oxide bioavailability and vascular function. Although exercise is known to improve vascular function, this is blunted in estrogen-deficient females post-menopause (PM). Here, we examined the effects of acute ... ...

    Abstract Menopause is associated with reduced nitric oxide bioavailability and vascular function. Although exercise is known to improve vascular function, this is blunted in estrogen-deficient females post-menopause (PM). Here, we examined the effects of acute exercise at differing intensities with and without inorganic nitrate (NO
    MeSH term(s) Humans ; Female ; Nitrates ; Dietary Supplements ; Exercise ; Antioxidants ; Nitric Oxide ; Postmenopause ; Beta vulgaris ; Double-Blind Method ; Cross-Over Studies ; Fruit and Vegetable Juices
    Chemical Substances Nitrates ; Antioxidants ; Nitric Oxide (31C4KY9ESH)
    Language English
    Publishing date 2023-10-05
    Publishing country United States
    Document type Randomized Controlled Trial ; Journal Article ; Research Support, N.I.H., Extramural ; Research Support, Non-U.S. Gov't
    ZDB-ID 219139-8
    ISSN 1522-1601 ; 0021-8987 ; 0161-7567 ; 8750-7587
    ISSN (online) 1522-1601
    ISSN 0021-8987 ; 0161-7567 ; 8750-7587
    DOI 10.1152/japplphysiol.00559.2023
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    Uc I Zs.249: Show issues Location:
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  8. Article ; Online: Colloidal transport and flocculation are the cause of the hyperenrichment of gold in nature.

    McLeish, Duncan F / Williams-Jones, Anthony E / Vasyukova, Olga V / Clark, James R / Board, Warwick S

    Proceedings of the National Academy of Sciences of the United States of America

    2021  Volume 118, Issue 20

    Abstract: Aqueous complexation has long been considered the only viable means of transporting gold to depositional sites in hydrothermal ore-forming systems. A major weakness of this hypothesis is that it cannot readily explain the formation of ultrahigh-grade ... ...

    Abstract Aqueous complexation has long been considered the only viable means of transporting gold to depositional sites in hydrothermal ore-forming systems. A major weakness of this hypothesis is that it cannot readily explain the formation of ultrahigh-grade gold veins. This is a consequence of the relatively low gold concentrations typical of ore fluids (tens of parts per billion [ppb]) and the fact that these "bonanza" veins can contain weight-percent levels of gold in some epithermal and orogenic deposits. Here, we present direct evidence for a hypothesis that could explain these veins, namely, the transport of the gold as colloidal particles and their flocculation in nanoscale calcite veinlets. These gold-bearing nanoveinlets bear a remarkable resemblance to centimeter-scale ore veins in many hydrothermal gold deposits and give unique insight into the scale invariability of colloidal flocculation in forming hyperenriched gold deposits. Using this evidence, we propose a model for the development of bonanza gold veins in high-grade deposits. We argue that gold transport in these systems is largely mechanical and is the result of exceptionally high degrees of supersaturation that preclude precipitation of gold crystals and instead lead to the formation of colloidal particles, which flocculate and form much larger masses. These flocculated masses aggregate locally, where they are seismically pumped into fractures to locally form veins composed largely of gold. This model explains how bonanza veins may form from fluids containing ppb concentrations of gold and does not require prior encapsulation of colloidal gold particles in silica gel, as proposed by previous studies.
    Language English
    Publishing date 2021-05-11
    Publishing country United States
    Document type Journal Article ; Research Support, Non-U.S. Gov't
    ZDB-ID 209104-5
    ISSN 1091-6490 ; 0027-8424
    ISSN (online) 1091-6490
    ISSN 0027-8424
    DOI 10.1073/pnas.2100689118
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    Zs.A 1148: Show issues Location:
    Je nach Verfügbarkeit (siehe Angabe bei Bestand)
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    Jg. 1995 - 2021: Lesesall (1.OG)
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  9. Article: Digital photography.

    Clark, James R

    Journal of esthetic and restorative dentistry : official publication of the American Academy of Esthetic Dentistry ... [et al.

    2004  Volume 16, Issue 3, Page(s) 147–148

    MeSH term(s) Equipment Design ; Image Processing, Computer-Assisted/standards ; Photography, Dental/instrumentation ; Photography, Dental/standards
    Language English
    Publishing date 2004-12-07
    Publishing country England
    Document type Journal Article
    ZDB-ID 2043146-6
    ISSN 1708-8240 ; 1496-4155
    ISSN (online) 1708-8240
    ISSN 1496-4155
    DOI 10.1111/j.1708-8240.2004.tb00025.x
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    Zs.A 3314: Show issues Location:
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  10. Article ; Online: Multiple environmental controls on phytoplankton growth strategies determine adaptive responses of the N : P ratio.

    Daines, Stuart J / Clark, James R / Lenton, Timothy M

    Ecology letters

    2014  Volume 17, Issue 4, Page(s) 414–425

    Abstract: The controls on the 'Redfield' N : P stoichiometry of marine phytoplankton and hence the N : P ratio of the deep ocean remain incompletely understood. Here, we use a model for phytoplankton ecophysiology and growth, based on functional traits and ... ...

    Abstract The controls on the 'Redfield' N : P stoichiometry of marine phytoplankton and hence the N : P ratio of the deep ocean remain incompletely understood. Here, we use a model for phytoplankton ecophysiology and growth, based on functional traits and resource-allocation trade-offs, to show how environmental filtering, biotic interactions, and element cycling in a global ecosystem model determine phytoplankton biogeography, growth strategies and macromolecular composition. Emergent growth strategies capture major observed patterns in marine biomes. Using a new synthesis of experimental RNA and protein measurements to constrain per-ribosome translation rates, we determine a spatially variable lower limit on adaptive rRNA:protein allocation and hence on the relationship between the largest cellular P and N pools. Comparison with the lowest observed phytoplankton N : P ratios and N : P export fluxes in the Southern Ocean suggests that additional contributions from phospholipid and phosphorus storage compounds play a fundamental role in determining the marine biogeochemical cycling of these elements.
    MeSH term(s) Adaptation, Physiological ; Environment ; Models, Biological ; Nitrogen/chemistry ; Nitrogen/metabolism ; Phosphorus/chemistry ; Phosphorus/metabolism ; Phytoplankton/growth & development ; Phytoplankton/physiology ; RNA, Ribosomal/metabolism ; Seawater/chemistry
    Chemical Substances RNA, Ribosomal ; Phosphorus (27YLU75U4W) ; Nitrogen (N762921K75)
    Language English
    Publishing date 2014-04
    Publishing country England
    Document type Journal Article ; Research Support, Non-U.S. Gov't
    ZDB-ID 1441608-6
    ISSN 1461-0248 ; 1461-023X
    ISSN (online) 1461-0248
    ISSN 1461-023X
    DOI 10.1111/ele.12239
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